JP5899147B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and is suitably applied to, for example, a color printer that performs multicolor printing.

  A conventional color printer includes a transfer unit having an endless conveyance belt that is placed on a belt driving roller and a driven roller in the middle of a conveyance path of the recording paper from a paper feed tray loaded with the recording paper to a recording paper discharge port. Is provided.

  Further, the color printer faces the linear portion of the conveyance belt, and, for example, four image forming units corresponding to four colors of black, yellow, magenta, and cyan are arranged in the conveyance direction of the recording paper by the conveyance belt. They are arranged in the order corresponding to black, yellow, magenta, and cyan from the upstream side to the downstream side.

  In the following description, an image forming unit corresponding to black is also referred to as a first image forming unit, and an image forming unit corresponding to yellow is also referred to as a second image forming unit.

  In the following description, an image forming unit corresponding to magenta is also referred to as a third image forming unit, and an image forming unit corresponding to cyan is also referred to as a fourth image forming unit.

  In each of the first to fourth image forming units, the photosensitive drum is provided such that a part of the surface is pressed against the conveying belt of the transfer unit, and the surface of the photosensitive drum is exposed to form an electrostatic latent image. An exposure head having a plurality of LED (Light Emitting Diode) elements is provided.

  Each of the first to fourth image forming units develops the electrostatic latent image formed on the surface of the photosensitive drum using a corresponding color (black, yellow, magenta, cyan) toner, and the photosensitive drum. A developing roller for forming a toner image on the surface is also provided.

  Further, the color printer is provided with a printer control unit that controls each unit of the color printer for forming a print image.

  Accordingly, the printer control unit individually controls the exposure heads of the corresponding first to fourth image forming units according to the color components of black, yellow, magenta, and cyan of the color image to be printed when forming the print image. To generate four types of head control data.

  The printer control unit rotates the photosensitive drum and the developing roller in opposite rotation directions in each of the first to fourth image forming units and rotates the conveyance belt of the transfer unit. In addition, the printer control unit feeds the recording paper from the paper feed tray and conveys it to the transfer unit.

  Then, the printer control unit sends the recording paper at a predetermined time interval before the recording paper conveyed to the transfer unit sequentially reaches between the conveyance belt and each of the photosensitive drums of the first to fourth image forming units. Corresponding head control data is sequentially sent to the exposure heads of the first to fourth image forming units.

  Therefore, the first image forming unit forms an electrostatic latent image on the surface of the photosensitive drum based on the head control data on the surface of the photosensitive drum at the timing when the head control data is given from the printer control unit to the exposure head, and also develops the developing roller. Thus, the electrostatic latent image is developed using black toner to start forming a toner image.

  Similarly to the first image forming unit, the second to fourth image forming units are provided on the surface of the photosensitive drum on the basis of the head control data by the exposure head at the timing when the head control data is given from the printer control unit to the exposure head. In addition to forming an electrostatic latent image, the electrostatic latent image is developed using black toner by a developing roller to start forming a toner image.

  Then, when the recording paper reaches between the conveyance belt and the photosensitive drum of the first image forming unit, the transfer unit conveys the recording paper by the conveyance belt and the photosensitive drum, and on the surface of the recording paper, The transfer of the black toner image formed on the surface is started.

  In addition, when the recording paper arrives between the transport belt and the photosensitive drums of the second to fourth image forming units, the transfer unit similarly transports the recording paper by the transport belt and the photosensitive drum, and on the surface of the recording paper. Then, the yellow, magenta, and cyan toner images formed on the surface of the photosensitive drum are sequentially transferred.

  In this way, the printer control unit conveys the recording sheet conveyed to the transfer unit by the conveyance belt and the photosensitive drums of the first to fourth image forming units, and on the surface of the recording sheet, black, yellow, magenta Then, toner images of four colors of cyan are transferred so as to be superimposed in order.

  Then, the printer control unit continuously pressurizes and heats the recording paper on which the four-color toner image is transferred to the surface, thereby fixing the four-color toner image on the surface of the recording paper.

  In this way, the color printer forms a print image (ie, prints) on the surface of the recording paper with toners of four colors of black, yellow, magenta, and cyan, and records the recording paper on which the printing image is formed. The paper was discharged from the paper discharge port (see, for example, Patent Document 1).

JP 2008-158167 A (Pages 5 to 9, FIGS. 1, 2, and 4)

  By the way, a conventional color printer is provided with one semiconductor integrated circuit having the above-described printer control unit (that is, a circuit block constituting the printer control unit is incorporated).

  The semiconductor integrated circuit is provided with a plurality of external terminals, and, for example, about 20 external terminals are electrically connected to the exposure heads of the first to fourth image forming units, respectively.

  As a result, the semiconductor integrated circuit individually controls the exposure heads of the first to fourth image forming units by sending corresponding head control data via about 20 external terminals.

  Here, recently, for example, five image forming units are provided so as to increase the number of image forming units as compared with the conventional color printer, and five color toner images are sequentially transferred onto the surface of the recording paper. It has been proposed to develop a new color printer that forms a more detailed printed image.

  When such a color printer is newly developed, a semiconductor integrated circuit having a printer control unit (that is, a circuit block constituting the printer control unit is built) corresponding to the increase in the number of image forming units is newly provided. Need to be developed.

  However, the newly developed semiconductor integrated circuit should be controlled as compared with the conventional semiconductor integrated circuit if all the exposure heads of the five image forming units are electrically connected and can be controlled. As the number of exposure heads increases by one, the circuit scale for controlling each exposure head increases.

  In addition, for a newly developed semiconductor integrated circuit, the number of exposure heads to be connected is increased by one as compared with the conventional semiconductor integrated circuit, and an external terminal for connecting the exposure head is once provided. For example, about 20 will be increased.

  In the case of a newly developed semiconductor integrated circuit, in the case of such a configuration, a physical formation location for making a circuit of increasing scale is secured, and a physical arrangement location of external terminals to be increased plural at a time. Therefore, the size (that is, the chip size) becomes larger than that of a conventional semiconductor integrated circuit.

  However, generally, as the size of a semiconductor integrated circuit increases, the unit price increases accordingly. For this reason, a newly developed semiconductor integrated circuit is reflected in the development cost of the semiconductor integrated circuit due to the unit price that increases as the size increases, and the development cost is significantly increased.

  Therefore, when a new color printer having five image forming units is developed, there is a problem that the development cost of the color printer itself increases remarkably as the development cost of the semiconductor integrated circuit increases.

  The present invention has been made in consideration of the above points, and intends to propose an image forming apparatus capable of reducing development costs.

In the present invention for solving the above problems, a plurality of imaging head, is formed by selecting less than the total number of connections possible maximum number Gae imaging head of the respective imaging head, connected connectable maximum image forming control unit is provided for delivering a head control data by controlling the timing out sent to the following image forming head, a plurality with a control method changing unit to which the image formation control unit changes the timing control method of the transmission timing only set the semiconductor integrated circuit, in the image forming control section provided for each of the plurality of semiconductor integrated circuits, one image forming control section provided in one half-conductor integrated circuit, the rest of the semiconductor integrated circuit functions as a master to control the image forming control section provided, the image forming control section provided in the remaining semiconductor integrated circuit, to function as a master Functions as a slave that is controlled by the image forming control unit, when not changing the timing control method by the control method changing unit, when one of the image forming control unit controls the output timing of the head control data to be transmitted to the imaging head The other image formation control unit controls the sending timing of the head control data to be sent to the image forming head according to the sending timing controlled by any of the image forming control units , and the control method changing unit sets the timing control method. When the image forming control unit is changed, when another image forming control unit controls the sending timing of the head control data to be sent to the image forming head, one of the image forming control units responds to the sending timing controlled by the other image forming control unit. The head control data sending timing sent to the image forming head is controlled .

Therefore, in the present invention, even when the number of image forming heads to be processed is increased as compared with the conventional case, the plurality of image forming heads are provided in one semiconductor integrated circuit to which all the image forming heads can be connected. without controlling the formation control unit, each connectable maximum number of imaging head is controlled me by the image formation control unit of the plurality of semiconductor integrated circuits less than the total number, the image formation control unit of the plurality of semiconductor integrated circuits In the master and slave settings, the timing control method can be changed according to the control order even when the head control data transmission timing is controlled by a timing control method that does not match the control order. As a result, the development cost of a semiconductor integrated circuit having an image formation control unit can be reduced.

According to the present invention, a plurality of image forming heads and image forming heads each having a maximum connectable number of image forming heads selected and less than the total number of the image forming heads are connected and less than the maximum connectable number of image forming heads. sending out by controlling the timing image formation control unit for sending the head control data is provided, and a plurality of semiconductor integrated circuit having a control method changing unit to which the image formation control unit changes the timing control method of the transmission timing set only, in the image forming control section provided for each of the plurality of semiconductor integrated circuit, the image forming control section provided on either one of the semi-conductor integrated circuit, an image forming provided in the remainder of the semiconductor integrated circuit functions as a master to control the control unit, the image forming control section provided in the remaining semiconductor integrated circuit, the image forming control unit functioning as the master Functions as a slave to be your, if you do not change the timing control method by the control method changing unit, when one of the image forming control unit controls the output timing of the head control data to be transmitted to the imaging head, other image forming If the control unit controls the sending timing of the head control data sent to the image forming head according to the sending timing controlled by any of the image forming control units , and the control method changing unit changes the timing control method, When the image formation control unit controls the sending timing of the head control data to be sent to the image forming head, one of the image forming control units controls the image forming head according to the sending timing controlled by the other image forming control unit. by the Turkey controls the output timing of the head control data to be sent, the imaging head of the processing compared with the conventional target Greater numbers, the plurality of imaging head, without control by the image forming control unit that is provided all the image forming head in one semiconductor integrated circuit connectable, connectable up each imaging head number controlled me by the image formation control unit of the plurality of semiconductor integrated circuits less than the total number, the master and slave setting for the image formation control unit of the plurality of semiconductor integrated circuits, the control transmission timing of the head control data Even when the timing control method is not suitable for the order, the timing control method can be changed in accordance with the control order, thereby reducing the development cost of the semiconductor integrated circuit having the image formation control unit. Thus, an image forming apparatus capable of reducing development costs can be realized.

1 is a schematic cross-sectional view showing an internal configuration of a color printer according to a first embodiment. 1 is a block diagram illustrating a circuit configuration of a color printer according to a first embodiment. FIG. It is a block diagram which shows the circuit structure of the semiconductor integrated circuit set so that it might function as a master. It is a block diagram which shows the circuit structure of the semiconductor integrated circuit set so that it might function as a slave. 10 is a timing chart for explaining control of sending timings of first to fifth head control data sent to the first to fifth exposure heads. It is a rough-line sectional view which shows the internal structure of the color printer by 2nd Embodiment. It is a block diagram which shows the circuit structure of the color printer by 2nd Embodiment. It is a block diagram which shows the circuit structure of the semiconductor integrated circuit set so that it might function as a master. It is a block diagram which shows the circuit structure of the semiconductor integrated circuit set so that it might function as a slave. It is a timing chart used for explanation of control of the sending timing of the sixth and first to fourth head control data sent to the sixth and first to fourth exposure heads.

The best mode for carrying out the invention (hereinafter, also referred to as an embodiment) will be described below with reference to the drawings. The description will be given in the following order.
(1) First embodiment (2) Second embodiment (3) Other embodiments

(1) First Embodiment (1-1) Internal Configuration of Color Printer In FIG. 1, reference numeral 1 denotes a color printer according to the first embodiment as a whole. The color printer 1 has, for example, a substantially box-shaped housing (hereinafter also referred to as a printer housing) 2.

  Incidentally, in the following description, the upper direction of the color printer 1 indicated by the arrow a1 in the figure when the color printer 1 is viewed facing the front surface 2A of the printer housing 2 is also referred to as the upward direction of the printer. The direction opposite to the upward direction of the printer is also referred to as the downward direction of the printer.

  In the following description, when it is not necessary to distinguish the upper direction of the printer and the lower direction of the printer, these are collectively referred to as a printer vertical direction.

  In the following description, the direction in front of the color printer 1 indicated by the arrow b1 in the figure when the color printer 1 is viewed facing the front surface 2A of the printer housing 2 is also referred to as the front direction of the printer. A direction opposite to the front direction of the printer is also referred to as a rear direction of the printer.

  In the following description, when there is no need to particularly distinguish the front direction of the printer and the rear direction of the printer, these are collectively referred to as the front-rear direction of the printer.

  Furthermore, in the following description, the left direction of the color printer 1 indicated by the arrow c1 in the figure when the color printer 1 is viewed facing the front surface 2A of the printer housing 2 is also referred to as the printer left direction. The direction opposite to the printer left direction is also referred to as the printer right direction.

  In the following description, when there is no need to particularly distinguish the printer left direction and the printer right direction, these are also collectively referred to as the printer left-right direction.

  The printer housing 2 is provided with a concave recording paper delivery section 2BX on the rear end portion of the upper surface 2B for placing the recording paper 5 as an image forming medium on which a print image is formed and delivering it to the user. ing.

  The printer housing 2 is a recording paper for discharging the recording paper 5 on which the print image is formed from the inside of the printer housing 2 to the recording paper delivery section 2BX at a predetermined position on the rear inner wall of the recording paper delivery section 2BX. A discharge port (not shown) is formed.

  On the other hand, in the printer housing 2, a cassette (hereinafter also referred to as a recording paper cassette) 6 for loading a plurality of recording papers 5 in a stacked state at the lower end is pulled out to the printer housing 2. It is provided so that it can be stored.

  In the printer housing 2, an image forming unit 7 is provided on the recording paper cassette 6 to form a print image so as to print a color image to be printed on the surface of the recording paper 5. .

  The image forming unit 7 includes four image forming units 10 to 13 corresponding to four colors of black (K), yellow (Y), magenta (M), and cyan (C) representing the color components of the print image. ing.

  The image forming unit 7 also includes one image forming unit 14 corresponding to clear (CL), which is a special color for giving the printed image gloss on the surface of the recording paper 5, for example.

  That is, the image forming unit 7 uses toners as developers of five colors of black (K), yellow (Y), magenta (M), cyan (C) as basic colors, and clear (CL) as special colors. Are used for one color so as not to overlap each other, and a total of five image forming units 10 to 14 for forming toner images as developer images to be described later are provided.

  In the following description, the image forming unit 10 that corresponds to the basic color black (K) and forms a toner image using the black (K) toner is also referred to as a first image forming unit 10.

  In the following description, the image forming unit 11 that corresponds to the basic color yellow (Y) and forms a toner image using the yellow (Y) toner is also referred to as a second image forming unit 11.

  Furthermore, in the following description, the image forming unit 12 corresponding to the basic color magenta (M) and forming a toner image using the magenta (M) toner is also referred to as a third image forming unit 12.

  Further, in the following description, the image forming unit 13 that corresponds to the basic color cyan (C) and forms a toner image using the cyan (C) toner is also referred to as a fourth image forming unit 13.

  Furthermore, in the following description, the image forming unit 14 that corresponds to the clear (CL) special color and forms a toner image using the clear (CL) toner is also referred to as a fifth image forming unit 14.

  Further, the image forming unit 7 conveys the recording paper 5 from the front side to the rear side, for example, on the surface of the recording paper 5 by the five colors (that is, black) formed by the first to fifth image forming units 10 to 14. , Yellow, magenta, cyan, and clear) toner images are sequentially transferred so as to overlap each other.

  Further, the image forming unit 7 also has a fixing unit 16 for forming a print image on the surface of the recording paper 5 so as to fix the five color toner images transferred by the transfer unit 15.

  The first to fifth image forming units 10 to 14 are arranged at predetermined equal intervals from the front side to the rear side (that is, from the upstream side to the downstream side in the conveyance direction when the recording paper 5 is conveyed by the transfer unit 15). The first image forming unit 10, the second image forming unit 11, the third image forming unit 12, the fourth image forming unit 13, and the fifth image forming unit 14 are arranged in this order.

  The first to fifth image forming units 10 to 14 are similarly configured except that different single color toners are used to form toner images.

  That is, each of the first to fifth image forming units 10 to 14 is provided with a detachable toner cartridge (not shown) that stores the corresponding color toner.

  The first to fifth image forming units 10 to 14 have photosensitive drums 20 to 24 as image carriers for carrying toner images on their surfaces, respectively, with a drum rotation axis parallel to the horizontal direction of the printer as the center. Is provided to be rotatable in one rotation direction indicated by an arrow d1.

  Incidentally, in the following description, the photosensitive drums 20 to 24 provided in the first to fifth image forming units 10 to 14 respectively correspond to the names of the first to fifth image forming units 10 to 14. Also referred to as fifth to fifth photosensitive drums 20 to 24.

  In the printer housing 2, for example, one unit drive motor (not shown) for driving the first to fifth image forming units 10 to 14 is disposed.

  The unit drive motor has an output shaft connected to the drum rotation shafts of the first to fifth photosensitive drums 20 to 24 via a plurality of gears (not shown).

  As a result, the first to fifth image forming units 10 to 14 rotate the first to fifth photosensitive drums 20 to 24 around the drum rotation axis in accordance with the operation of the unit drive motor when the print image is formed. Can be rotated in the direction.

  Further, in each of the first to fifth image forming units 10 to 14, a charging roller (not shown) as a charging unit is centered on a roller rotation axis parallel to the horizontal direction of the printer, and is inclined frontward on the surface of the charging roller. In a state where the lower part is pressed against the upper rear part of the surface of the first to fifth photosensitive drums 20 to 24, the lower part is provided to be rotatable in the other rotation direction opposite to the one rotation direction.

  Incidentally, in the following description, the charging rollers provided in the first to fifth image forming units 10 to 14 correspond to the names of the first to fifth image forming units 10 to 14, respectively. Also called a charging roller.

  In the first to fifth image forming units 10 to 14, the roller rotation shafts of the first to fifth charging rollers are respectively connected to the first to fifth photosensitive drums 20 to 24 via an even number of gears (not shown). It is connected to the drum rotation shaft.

  Therefore, the first to fifth image forming units 10 to 14 move the first to fifth charging rollers in conjunction with the rotation of the first to fifth photosensitive drums 20 to 24 in one rotation direction at the time of printing image formation. It can be rotated in the other rotation direction around the roller rotation axis.

  The first to fifth charging rollers are electrically connected to a predetermined charging roller voltage source (not shown), and a DC voltage having a predetermined voltage value is applied by the charging roller voltage source when a print image is formed. Is done.

  Thus, the first to fifth image forming units 10 to 14 form electrostatic latent images on the surfaces of the first to fifth photosensitive drums 20 to 24 via the first to fifth charging rollers during the formation of the print image. It can be charged to a possible state.

  Further, each of the first to fifth image forming units 10 to 14 includes, for example, exposure heads 25 to 29 each having a plurality of LED elements and a lens array as image forming heads. In the surface of 24 thru | or 24, it arrange | positions facing the upper part used as the part electrically charged by the 1st thru | or 5th charging roller.

  Incidentally, in the following description, the exposure heads 25 to 29 provided in the first to fifth image forming units 10 to 14 respectively correspond to the names of the first to fifth image forming units 10 to 14. Also referred to as fifth exposure heads 25 to 29.

  Therefore, the first to fifth image forming units 10 to 14 are arranged on the surfaces of the first to fifth photosensitive drums 20 to 24 by the first to fifth exposure heads 25 to 29 when the print image is formed. An electrostatic latent image having a potential different from that of the unexposed portion can be formed by exposing the charged portion by the charging roller.

  Further, in each of the first to fifth image forming units 10 to 14, a developing roller (not shown) as a developer carrying member that carries toner on the surface thereof is centered on a roller rotation axis parallel to the left-right direction of the printer, and In a state in which the rear diagonally lower part of the surface of the developing roller is pressed against the front diagonally upper part of the surfaces of the first to fifth photosensitive drums 20 to 24, which is the electrostatic latent image forming part, in the other rotation direction. It is provided so as to be rotatable.

  Incidentally, in the following description, the developing rollers provided in the first to fifth image forming units 10 to 14 correspond to the names of the first to fifth image forming units 10 to 14, respectively. Also called a developing roller.

  In the first to fifth image forming units 10 to 14, the roller rotation shafts of the first to fifth developing rollers are respectively connected to the first to fifth photosensitive drums 20 to 24 via an even number of gears (not shown). It is connected to the drum rotation shaft.

  Accordingly, the first to fifth image forming units 10 to 14 move the first to fifth developing rollers in conjunction with the rotation of the first to fifth photosensitive drums 20 to 24 in one rotation direction when forming a print image. It can be rotated in the other rotation direction around the roller rotation axis.

  The first to fifth developing rollers are electrically connected to a predetermined developing roller voltage source (not shown), and a DC voltage having a predetermined voltage value is applied by the developing roller voltage source when a print image is formed. Has been.

  Thus, the first to fifth image forming units 10 to 14 carry the toner from the surfaces of the first to fifth photosensitive drums 20 while carrying the toner on the surfaces of the first to fifth developing rollers at the time of forming the print image. The electrostatic latent image can be transferred (attached) to the electrostatic latent image on surfaces 24 to 24 and developed (that is, a toner image in which the electrostatic latent image is visualized with toner) can be developed.

  Further, in the first to fifth image forming units 10 to 14, a supply roller (not shown) as a supply unit for supplying toner to the surfaces of the first to fifth developing rollers is rotated in parallel with the horizontal direction of the printer. Centering on the shaft, the rear part of the surface of the supply roller is pressed against the front part of the surface of the first to fifth developing rollers so as to be rotatable in the other rotation direction.

  In the following description, the supply rollers provided in the first to fifth image forming units 10 to 14 correspond to the names of the first to fifth image forming units 10 to 14, respectively. Also called a supply roller.

  In each of the first to fifth image forming units 10 to 14, the roller rotation shafts of the first to fifth supply rollers are respectively connected to the roller rotation shafts of the first to fifth developing rollers via an odd number of gears (not shown). It is connected to.

  Therefore, the first to fifth image forming units 10 to 14 move the first to fifth supply rollers to the roller rotation shaft in conjunction with the rotation of the first to fifth developing rollers in the other rotation direction during the formation of the print image. Can be rotated in the other direction of rotation.

  The first to fifth supply rollers are electrically connected to a predetermined supply roller voltage source (not shown), and a DC voltage having a predetermined voltage value is applied by the supply roller voltage source when a print image is formed. Has been.

  Thus, the first to fifth image forming units 10 to 14 charge the surfaces of the first to fifth supply rollers so that the toner can be supplied to the first to fifth developing rollers when forming a print image. Can do.

  On the other hand, the transfer unit 15 is disposed from the lower part of the first image forming unit 10 to the vicinity of the lower part of the fifth image forming unit 14 in the central part in the printer housing 2.

  That is, the transfer unit 15 is provided with a drive roller 35 obliquely below the rear of the fifth image forming unit 14 so as to be rotatable in the other rotation direction about a roller rotation axis parallel to the horizontal direction of the printer.

  In addition, the transfer unit 15 is provided with a tension roller 36 below the first image forming unit 10 so as to be rotatable in other rotational directions around a roller rotational axis parallel to the left-right direction of the printer.

  Further, the transfer unit 15 extends from the drive roller 35 to the tension roller 36, and is an endless transport belt (hereinafter also referred to as a transfer belt) for electrostatically attracting and transporting the recording paper 5 for toner image transfer. 37 is stretched.

  As a result, the transfer unit 15 causes the first five portions on the surface of the upper flat portion (hereinafter also referred to as the upper flat portion) of the pair of flat portions between the drive roller 35 and the tension roller 36 to be transferred to the transfer belt 37. Through the surface of the fifth to fifth photosensitive drums 20 to 24, they are brought into contact with the lower part.

  In the transfer unit 15, the roller rotation shaft of the drive roller 35 is connected to the output shaft of one transfer unit drive motor (not shown) via, for example, a plurality of gears (not shown).

  Therefore, the transfer unit 15 rotates the drive roller 35 in the other rotation direction around the roller rotation axis in accordance with the operation of the transfer unit drive motor during the formation of the print image, and the tension roller 36 in conjunction with the rotation. At the same time, the transfer belt 37 can be rotated in the other rotation direction.

  Further, inside the transfer belt 37, five transfer rollers 38 to 42 corresponding to the first to fifth photosensitive drums 20 to 24 are arranged in order from the front to the rear, and the rollers are parallel to the horizontal direction of the printer. It is provided so as to be able to rotate in the other rotation direction around the rotation axis.

  Incidentally, in the following description, the transfer roller 38 located at the forefront inside the transfer belt 37 is also referred to as a first transfer roller 38, and the transfer roller 39 positioned second from the front is also referred to as a second transfer roller 39. The transfer roller 40 positioned third from the front is also referred to as a third transfer roller 40.

  Further, in the following description, the transfer roller 41 located fourth from the front inside the transfer belt 37 is also referred to as a fourth transfer roller 41, and is located fifth from the front (that is, the rearmost). 42 is also referred to as a fifth transfer roller 42.

  As a result, the transfer unit 15 causes the upper portions of the surfaces of the first to fifth transfer rollers 38 to 42 to face the surfaces of the corresponding first to fifth photosensitive drums 20 to 24 via the upper flat portion of the transfer belt 37. Is pressed against the lower part which is the opposite part.

  The first to fifth transfer rollers 38 to 42 are electrically connected to a predetermined transfer roller voltage source, and a DC voltage having a predetermined voltage value is applied by the transfer roller voltage source when a print image is formed. Yes.

  As a result, the transfer unit 15 forms the recording paper 5 between the upper flat portion of the transfer belt 37 and the first to fifth photosensitive drums 20 to 24 of the first to fifth image forming units 10 to 14 when the print image is formed. The toner images on the surfaces of the first to fifth photosensitive drums 20 to 24 are applied to the surface of the recording paper 5 by the action of the Coulomb force generated on the first to fifth transfer rollers 38 to 42 while being conveyed while being sequentially sandwiched. Can be transferred.

  Incidentally, in the following description, on the surface of the upper flat portion of the transfer belt 37, the frontmost position among the five positions pressed against the surfaces of the first to fifth photosensitive drums 20 to 24 is used for the first transfer execution. Also referred to as a position, the second position from the front is also referred to as a second transfer execution position, and the third position from the front is also referred to as a third transfer execution position.

  In the following description, the fourth position from the front among the five positions pressed against the surfaces of the first to fifth photosensitive drums 20 to 24 on the surface of the upper flat portion of the transfer belt 37 is the fourth position. It is also called a transfer execution position, and the fifth position from the front (that is, the rearmost position) is also called a fifth transfer execution position.

  In addition, the fixing unit 16 is disposed on the rear side of the fifth image forming unit 14 and the transfer unit 15 that are closer to the rear end in the center of the printer housing 2.

  That is, the fixing unit 16 includes a substantially box-shaped fixing unit housing 45. The fixing unit housing 45 is formed with a recording paper path for passing the recording paper 5 in the center.

  The fixing unit housing 45 has the upper end facing the fifth image forming unit 14 with one opening of the recording paper path facing the front and the other opening facing the rear, and the lower end is It is arranged to face the transfer part 15.

  Incidentally, in the following description, one opening portion facing the front side of the recording paper path in the fixing unit housing 45 is also called a recording paper take-in port, and the other opening portion facing the rear side is called the recording paper feed opening. Also called.

  The fixing unit housing 45 has a cylindrical heat generating roller 46 at the upper end, with the lower part of the surface entering the recording paper path, with the roller rotation axis parallel to the horizontal direction of the printer as the center. It is provided to be rotatable in one rotation direction.

  In the fixing unit 16, the roller rotation shaft of the heat generating roller 46 is connected to the output shaft of one fixing unit driving motor via a plurality of gears (not shown), for example.

  As a result, the fixing unit 16 can rotate the heat generating roller 46 in one rotation direction around the roller rotation axis in accordance with the operation of the fixing unit driving motor when the print image is formed.

  The fixing unit housing 45 has a pressure roller 47 at the lower end centered on a roller rotation axis parallel to the horizontal direction of the printer, and an upper portion of the surface of the pressure roller 47 is below the surface of the heat generating roller 46. It is provided so as to be able to rotate in the other rotation direction in a state where it is pressed against the side portion with a predetermined pressure.

  In the fixing unit 16, the roller rotation shaft of the pressure roller 47 is connected to the roller rotation shaft of the heat generation roller 46 through an even number of gears (not shown).

  As a result, the fixing unit 16 keeps pressing the surface of the pressure roller 47 against the surface of the heat generation roller 46 at a predetermined pressure when forming a print image, and interlocks with the rotation of the heat generation roller 46 in one rotation direction. The pressure roller 47 can be rotated in the other rotation direction around the roller rotation axis.

  Incidentally, the heating roller 48 has a heater 48 disposed therein. The heater 48 is electrically connected to a predetermined heater voltage source, and a predetermined voltage for heating is applied by the heater voltage source when a printed image is formed.

  The fixing unit housing 45 is provided with a thermistor 49 for detecting the surface temperature of the heat generating roller 46 at a predetermined position on the upper end.

  The thermistor 49 is electrically connected to a predetermined temperature control unit (not shown). Then, the temperature control unit appropriately controls on / off of the heater voltage source based on the surface temperature detected by the thermistor 49 during the formation of the print image, thereby maintaining the surface temperature of the heat generating roller 46 at a predetermined temperature. Yes.

  As a result, the fixing unit 16 conveys the recording paper 5 on which the toner image is transferred on the surface so as to be sandwiched between the heat generating roller 46 and the pressure roller 47 that are rotating in reverse to each other. The toner image can be fixed on the surface of the recording paper 5 by heating and pressing.

  In addition to this, a plurality of recording papers 5 stacked from the recording paper cassette 6 are separated one by one from the top in a predetermined position facing the upper front end of the recording paper cassette 6 in the printer housing 2. A pair of recording paper feeding rollers 50 and 51 for feeding out in this manner are provided so as to be able to rotate in other rotational directions around a roller rotation axis parallel to the printer left-right direction.

  Also, a pair of recording paper transports for transporting the recording paper 5 so as to be sandwiched between the surfaces of the recording paper 5 at predetermined positions on the front side of the pair of recording paper feeding rollers 50 and 51 in the printer casing 2. The rollers 52 and 53 are provided so as to be rotatable in one rotation direction and the other rotation direction opposite to each other around a roller rotation axis parallel to the horizontal direction of the printer.

  Further, in the printer housing 2, the recording paper 5 is also transported so as to be sandwiched between the surfaces of the recording paper transport rollers 52, 53, also before the transfer unit 15 which is obliquely above the rear. A pair of recording paper conveyance rollers 54 and 55 are provided so as to be rotatable in one rotation direction and the other rotation direction opposite to each other around a roller rotation axis parallel to the horizontal direction of the printer.

  In the printer casing 2, the arrangement positions of the pair of recording paper conveyance rollers 54 and 55 from the vicinity of the arrangement position of the pair of recording paper feeding rollers 50 and 51 through the arrangement positions of the pair of recording paper conveyance rollers 52 and 53. Various conveyance path forming components such as a plurality of conveyance guides (not shown) and other rollers (not shown) are appropriately arranged over the vicinity.

  As a result, in the printer casing 2, a pair of recording paper feeding rollers 50 and 51, a pair of recording paper conveyance rollers 52 and 53, a pair of recording paper conveyance rollers 54 and 55, and conveyance path forming components are provided at the lower front end. A feeding conveyance path 56 is formed for feeding the recording paper 5 out of the recording paper cassette 6 for forming a print image (that is, for printing) and conveying it to the transfer unit 15.

  In the printer housing 2, a pair of recording paper transport rollers 60 and 61 for transporting the recording paper 5 so as to be sandwiched between the surfaces of the recording paper 5 are also provided at predetermined positions after the fixing unit 16, respectively. It is provided so as to be rotatable in one rotation direction and the other rotation direction opposite to each other around a roller rotation axis parallel to the printer left-right direction.

  Further, in the printer housing 2, the recording paper 5 is sandwiched between the surfaces of the recording paper discharge rollers near the recording paper discharge port at the rear upper end portion above the pair of recording paper transport rollers 60 and 61. A pair of recording paper discharge rollers 62 and 63 for discharging from the paper discharge port are provided so as to be able to rotate in one rotation direction and the other rotation direction opposite to each other around a roller rotation axis parallel to the horizontal direction of the printer. ing.

  In the printer housing 2, the vicinity of the position where the pair of recording paper discharge rollers 62, 63 passes from the vicinity of the recording paper feed opening of the fixing unit housing 45 via the position where the pair of recording paper transport rollers 60, 61 is located. Various conveying path forming parts such as a plurality of conveying guides (not shown) and other rollers (not shown) are appropriately arranged.

  As a result, the recording paper 5 is recorded in the printer housing 2 at the rear end by a pair of recording paper transport rollers 60 and 61, a pair of recording paper discharge rollers 62 and 63, and transport path forming components. A discharge conveyance path 64 is formed for conveying the paper from the paper feed opening to the recording paper discharge port of the printer housing 2 and discharging the recording paper from the recording paper discharge port.

  In the printer housing 2, for example, when the recording paper 5 is transported via the feeding transport path 56, a predetermined distance between the pair of recording paper transport rollers 52 and 53 and the pair of recording paper transport rollers 54 and 55 is set. A sensor 65 for detecting whether or not the recording paper 5 has arrived at the pass / fail detection position.

  With this configuration, the color printer 1 operates the unit drive motor when forming a print image to operate the first to fifth photosensitive drums 20 to 24 and the first to fifth image forming units 10 to 14. The fifth charging roller, the first to fifth developing rollers, and the first to fifth supply rollers are rotated in one rotation direction or the other rotation direction.

  The color printer 1 operates the transfer unit driving motor to rotate the transfer belt 37 in the other rotation direction, and operates the fixing unit driving motor to move the heat generating roller 46 and the pressure roller 47 in one rotation direction opposite to each other. Rotate in the other direction of rotation.

  Further, the color printer 1 operates one or a plurality of motors (not shown) for conveying the recording paper 5 (hereinafter also referred to as a conveyance motor) to operate a pair of recording paper conveyance rollers 52 and 53 and a pair of recording papers. The conveyance rollers 54 and 55, the pair of recording paper conveyance rollers 60 and 61, the pair of recording paper discharge rollers 62 and 63, and the like are rotated in one rotation direction or the other rotation direction for conveying the recording paper 5.

  In addition, the color printer 1 operates a motor (not shown) for feeding the recording paper 5 out of the recording paper cassette 6 (hereinafter also referred to as a feeding motor), so that the pair of recording paper feeding rollers 50 and 51 are moved to the recording paper 5. The recording paper 5 is fed out from the recording paper cassette 6 and conveyed to the transfer unit 15 via the feeding conveyance path 56 by being rotated in the other rotation direction.

  When the color printer 1 detects that the recording paper 5 being conveyed to the transfer unit 15 has reached the passage presence / absence detection position via the sensor 65, the recording paper 5 corresponds to the first to fifth in response to this. Head control data is sequentially sent to the first to fifth exposure heads 25 to 29 of the first to fifth image forming units 10 to 14 at a sending timing at a predetermined time interval before sequentially reaching the transfer execution position.

  Incidentally, in the following description, the first to fifth head controls corresponding to the names of the first to fifth exposure heads 25 to 29 correspond to the head control data sent to the first to fifth exposure heads 25 to 29, respectively. Also called data.

  Thereby, the first image forming unit 10 gives the first head control data to the first exposure head 25 before the recording paper 5 reaches the first transfer execution position of the transfer belt 37.

  In response to this, the first image forming unit 10 forms an electrostatic latent image on the surface of the first photosensitive drum 20 by the first exposure head 25 based on the first head control data, and also black by the first developing roller. The electrostatic latent image is developed with the toner of and the toner image is started to be formed.

  The second image forming unit 11 also includes a second exposure head after the first image forming unit 10 starts forming a toner image and before the recording paper 5 reaches the second transfer execution position of the transfer belt 37. The second head control data is given to 26.

  In response to this, the second image forming unit 11 forms an electrostatic latent image on the surface of the second photosensitive drum 21 by the second exposure head 26 based on the second head control data, and yellow by the second developing roller. The electrostatic latent image is developed with the toner of and the toner image is started to be formed.

  Further, the third image forming unit 12 includes a third exposure head after the second image forming unit 11 starts forming a toner image and before the recording paper 5 reaches the third transfer execution position of the transfer belt 37. The third head control data is given to 27.

  In response to this, the third image forming unit 12 forms an electrostatic latent image on the surface of the third photosensitive drum 22 by the third exposure head 27 based on the third head control data, and magenta by the third developing roller. The electrostatic latent image is developed with the toner of and the toner image is started to be formed.

  Further, the fourth image forming unit 13 includes a fourth exposure head after the third image forming unit 12 starts forming a toner image and before the recording paper 5 reaches the fourth transfer execution position of the transfer belt 37. The fourth head control data is given to 28.

  In response to this, the fourth image forming unit 13 forms an electrostatic latent image on the surface of the fourth photosensitive drum 23 by the fourth exposure head 28 based on the fourth head control data, and cyan by the fourth developing roller. The electrostatic latent image is developed with the toner of and the toner image is started to be formed.

  Furthermore, the fifth image forming unit 14 performs the fifth exposure after the fourth image forming unit 13 starts forming the toner image and before the recording paper 5 reaches the fifth transfer execution position of the transfer belt 37. The fifth head control data is given to the head 29.

  In response to this, the fifth image forming unit 14 forms an electrostatic latent image on the surface of the fifth photosensitive drum 24 by the fifth exposure head 29 based on the fifth head control data, and clears it by the fifth developing roller. The electrostatic latent image is developed with the toner of and the toner image is started to be formed.

  The color printer 1 receives the recording paper 5 conveyed to the transfer unit 15 by the transfer belt 37, and when the recording paper 5 reaches the first transfer execution position in the transfer unit 15, the transfer belt 37 and the first The black toner image formed on the surface of the first photosensitive drum 20 on the surface of the recording paper 5 while transporting the recording paper 5 sandwiched between the first photosensitive drum 20 of the image forming unit 10. Transcript.

  When the recording paper 5 reaches the second transfer execution position in the transfer unit 15, the color printer 1 sandwiches the recording paper 5 between the transfer belt 37 and the second photosensitive drum 21 of the second image forming unit 11. The yellow toner image formed on the surface of the second photosensitive drum 21 is transferred to the surface of the recording paper 5 while being conveyed.

  Further, when the recording paper 5 reaches the third transfer execution position in the transfer unit 15, the color printer 1 sandwiches the recording paper 5 between the transfer belt 37 and the third photosensitive drum 22 of the third image forming unit 12. The magenta toner image formed on the surface of the third photosensitive drum 22 is transferred to the surface of the recording paper 5 while being conveyed.

  Further, when the recording paper 5 reaches the fourth transfer execution position in the transfer unit 15, the color printer 1 sandwiches the recording paper 5 between the transfer belt 37 and the fourth photosensitive drum 23 of the fourth image forming unit 13. The cyan toner image formed on the surface of the fourth photosensitive drum 23 is transferred to the surface of the recording paper 5 while being conveyed.

  Furthermore, when the recording paper 5 reaches the fifth transfer execution position in the transfer unit 15, the color printer 1 sandwiches the recording paper 5 between the transfer belt 37 and the fifth photosensitive drum 24 of the fifth image forming unit 14. While being conveyed in this manner, the clear toner image formed on the surface of the fifth photosensitive drum 24 is transferred to the surface of the recording paper 5.

  In this way, the color printer 1 continuously conveys the recording paper 5 conveyed to the transfer unit 15 by the transfer belt 37 and the first to fifth photosensitive drums 20 to 24 of the first to fifth image forming units 10 to 14. On the surface of the recording paper 5, toner images of five colors of black, yellow, magenta, cyan, and clear are transferred so as to be sequentially superimposed, and then transferred to the fixing unit 16.

  Then, the color printer 1 takes in the recording paper 5 in the fixing unit 16 between the heating roller 46 and the pressure roller 47 that are rotating in reverse from the recording paper take-in port.

  As a result, the color printer 1 fixes the five color toner images on the surface of the recording paper 5 by applying pressure while heating the recording paper 5 between the heat generating roller 46 and the pressure roller 47 in the fixing unit 16. After that, the paper is delivered to the discharge conveyance path 64 from the recording paper feed opening.

  In this manner, the color printer 1 fixes the five color toner images on the surface of the recording paper 5 by the fixing unit 16 to form a print image, and the recording paper 5 on which the print image has been formed is discharged to the discharge conveyance path 64. Can be discharged from the recording paper discharge port to the recording paper delivery unit 2BX.

(1-2) Circuit Configuration of Color Printer Next, the circuit configuration of the color printer 1 will be described with reference to FIGS. As shown in FIGS. 2 to 4, the color printer 1 includes a host device 70 such as a personal computer that instructs the color printer 1 to print a color image to be printed, and the communication units 71 and 72. Wirelessly or wired so that they can communicate.

  The color printer 1 is provided with a CPU (Central Processing Unit) 74 that controls overall image processing for printing.

  Incidentally, in the following description, the CPU 74 that controls the entire image processing for printing is also referred to as an image processing CPU 74.

  The color printer 1 also includes printer control units 75 and 76 that can control the respective units of the color printer 1 for forming a print image (that is, circuit blocks constituting the printer control units 75 and 76 are built in). For example, two semiconductor integrated circuits 77 and 78 having the same configuration are also provided.

  The two semiconductor integrated circuits 77 and 78 are the first to fifth exposure heads provided in the color printer 1 with the maximum connectable number of exposure heads that can be electrically connected to the printer control units 75 and 76 as control objects, respectively. For example, four is selected which is smaller than the total number of 25 to 29.

  That is, the two semiconductor integrated circuits 77 and 78 are individually connected to the printer control units 75 and 76 by electrically connecting a maximum of four exposure heads in the same manner as the semiconductor integrated circuit provided in the conventional color printer. It is formed so that it can be controlled.

  Incidentally, in the following description, the maximum connectable number of exposure heads that can be electrically connected to the printer control units 75 and 76 of the two semiconductor integrated circuits 77 and 78 as control targets is also referred to as the maximum number of heads that can be connected. .

  In the following description, the total number of first to fifth exposure heads 25 to 29 provided in the color printer 1 is also referred to as the total number of heads.

  Thus, the two semiconductor integrated circuits 77 and 78 are provided with five first to fifth image forming units 10 to 14 (that is, five first to fifth exposure heads 25 to 29) in the color printer 1. However, it is formed in the same size as a semiconductor integrated circuit provided in a conventional color printer by suppressing an increase in circuit scale and a significant increase in the number of external terminals.

  Incidentally, since the maximum number of heads that can be connected to each of the two semiconductor integrated circuits 77 and 78 is smaller than the total number of heads, it is necessary to distribute and connect the first to fifth exposure heads 25 to 29.

  In the two semiconductor integrated circuits 77 and 78, when the printer control sections 75 and 76 respectively control each section such as the first to fifth exposure heads 25 to 29 of the color printer 1 for forming a print image, There is a possibility that the toner images of five colors cannot be easily transferred onto the surface of the recording paper 5 so as to be superimposed.

For this reason, even if the two semiconductor integrated circuits 77 and 78 have the same configuration as described above, the printer control sections 75 and 76 do not independently control each section of the color printer 1 for forming a print image. without are configured to be set to function as a master or slave each other, and controls the units of the color printer 1.

  That is, the two semiconductor integrated circuits 77 and 78 are controlled by their own printer control units 75 and 76, the master that controls the other printer control units 75 and 76, and the other printer control units 75 and 76, respectively. Setting terminals 80 and 81 are provided for arbitrarily setting the function as a slave by an external operation.

  In addition to this, the two semiconductor integrated circuits 77 and 78 are respectively provided with image processing units 82 and 83 (that is, circuit blocks constituting the image processing units 82 and 83 are built in). The image processing units 82 and 83 are electrically connected to the image processing CPU 74 described above.

  The two semiconductor integrated circuits 77 and 78 are provided with PLLs 84 and 85 for generating their own operation clocks CL1 and CL2, respectively (that is, circuit blocks constituting the PLLs 84 and 85 are built in).

  Incidentally, the PLLs 84 and 85 of the two semiconductor integrated circuits 77 and 78 generate operation clocks CL1 and CL2 having a predetermined same frequency.

  Further, the two semiconductor integrated circuits 77 and 78 are also provided with clock control units 86 and 87 for individually controlling the supply / non-supply of the operation clocks CL1 and CL2 generated by the PLLs 84 and 85, respectively (that is, clock control). The circuit blocks constituting the parts 86 and 87 are also built in).

  In the two semiconductor integrated circuits 77 and 78, for example, in the clock control units 86 and 87, whether or not the operation clocks CL1 and CL2 are supplied is set by an external operation on the setting terminals 80 and 81.

  Further, the printer control units 75 and 76 of the two semiconductor integrated circuits 77 and 78 have CPUs 90 and 91 (hereinafter also referred to as printer control CPUs) 90 that can control all the printer control units 75 and 76, respectively. Is provided.

  Further, the printer control units 75 and 76 of the two semiconductor integrated circuits 77 and 78 access the other printer control units 75 and 76 by their own printer control CPUs 90 and 91, respectively, and other printer control CPUs 90 and 91. There are provided external access control units 92 and 93 for controlling access to the device from itself.

  Furthermore, the printer control units 75 and 76 of the two semiconductor integrated circuits 77 and 78 output various control commands C1 output from their own printer control CPUs 90 and 91 and output from the other printer control CPUs 90 and 91, respectively. Command selectors 94 and 95 are provided for selecting one of the various control commands to be given to the respective units.

  The two semiconductor integrated circuits 77 and 78 operate, for example, a control command C1 to be selected to be given to each unit of the printer control units 75 and 76 by the command selectors 94 and 95 from the outside with respect to the setting terminals 80 and 81. It is set by.

  The printer control units 75 and 76 of the two semiconductor integrated circuits 77 and 78 are respectively a drive system for controlling the motor 97 for operating the color printer 1 for forming a print image and the sensor 65 described above. Control units 98 and 99 are provided.

  Incidentally, the motor 97 for operating the color printer 1 for forming a print image is the above-described unit driving motor, transfer unit driving motor, fixing unit driving motor, one or a plurality of transport motors, and a feeding motor.

  Further, the printer control units 75 and 76 of the two semiconductor integrated circuits 77 and 78 are provided with head control units 100 and 101 for controlling a maximum of four first to fifth exposure heads 25 to 29, respectively. Yes.

  The printer control units 75 and 76 of the two semiconductor integrated circuits 77 and 78 respectively control the first to fifth heads from the head control units 100 and 101 to the first to fifth exposure heads 25 to 29 at the maximum. Transmission timing control units 102 and 103 for controlling transmission timings for transmitting the data D1 to D5 are also provided.

  In this case, in the two semiconductor integrated circuits 77 and 78, the transmission timing control units 102 and 103 are provided with counters 105 and 106 that count in synchronization with the operation clocks CL1 and CL2, respectively.

  In the two semiconductor integrated circuits 77 and 78, the transmission timing control units 102 and 103 send the first to fifth head control data D1 to D5 corresponding to the four first to fifth exposure heads 25 to 29 at the maximum. Are stored in timing information storage registers 107 and 108 for storing timing information indicating transmission timings for sequentially transmitting.

  Further, in the two semiconductor integrated circuits 77 and 78, the transmission timing control units 102 and 103 transmit the timings for notifying the head control units 100 and 101 of the transmission timings of the first to fifth head control data D1 to D5, respectively. Timing notification units 109 and 110 that generate and send notification data D6 to D10 are provided.

  Incidentally, in the following description, the sending timing of the first head control data D1 to the first exposure head 25 is also called the first sending timing, the timing information indicating the first sending timing is also called the first timing information, The transmission timing notification data D6 for notifying one transmission timing is also referred to as first transmission timing notification data D6.

  In the following description, the transmission timing of the second head control data D2 to the second exposure head 26 is also referred to as second transmission timing, and the timing information indicating the second transmission timing is also referred to as second timing information. The transmission timing notification data D7 for notifying the second transmission timing is also referred to as second transmission timing notification data D7.

  Further, in the following description, the transmission timing of the third head control data D3 to the third exposure head 27 is also referred to as third transmission timing, and the timing information indicating the third transmission timing is also referred to as third timing information. The transmission timing notification data D8 for notifying the 3 transmission timing is also referred to as third transmission timing notification data D8.

  Furthermore, in the following description, the transmission timing of the fourth head control data D4 to the fourth exposure head 28 is also referred to as a fourth transmission timing, and timing information indicating the fourth transmission timing is also referred to as fourth timing information. The transmission timing notification data D9 for notifying the 4 transmission timing is also referred to as fourth transmission timing notification data D9.

  Further, in the following description, the sending timing of the fifth head control data D5 to the fifth exposure head 29 is also called the fifth sending timing, the timing information indicating the fifth sending timing is also called the fifth timing information, The transmission timing notification data D10 for notifying the fifth transmission timing is also referred to as fifth transmission timing notification data D10.

  In the two semiconductor integrated circuits 77 and 78, the transmission timing control units 102 and 103 are provided with count start trigger registers 111 and 112 for outputting count start trigger data D11 for causing the counters 105 and 106 to start counting, respectively. ing.

  Further, in the two semiconductor integrated circuits 77 and 78, the transmission timing control units 102 and 103 are connected to the counters 105 and 106 based on communication with the timing notification units 109 and 110 of the other transmission timing control units 102 and 103, respectively. Sample circuits 113 and 114 for generating and outputting count start trigger data D12 for starting counting are provided.

  In the following description, the count start trigger data D11 generated by the count start trigger registers 111 and 112 is also referred to as first count start trigger data D11, and the count start trigger data D12 generated by the sample circuits 113 and 114 is Also called 2-count start trigger data D12.

  Further, in the two semiconductor integrated circuits 77 and 78, the transmission timing control units 102 and 103 are output from the first count start trigger data D11 output from the count start trigger registers 111 and 112 and the sample circuits 113 and 114, respectively. Trigger selectors 115 and 116 that select one of the second count start trigger data D12 and the counters 105 and 106 are also provided.

  The two semiconductor integrated circuits 77 and 78, for example, set the first count start trigger data D11 or the second count start trigger data D12 to be selected to be given to the counters 105 and 106 in the trigger selectors 115 and 116, as setting terminals. 80 and 81 are set by an external operation.

  With this configuration, one of the two semiconductor integrated circuits 77 and 78 is operated so that, for example, the setting terminal 80 functions as the master of the printer control unit 75 when the color printer 1 is manufactured. Has been.

  Accordingly, in one semiconductor integrated circuit 77, the clock control unit 86 is supplied to the image processing unit 82 by operating the setting terminal 80 and the operation clock CL1 generated by the PLL 84, and each unit including the printer control CPU 90 of the printer control unit 75 is provided. Also set to supply.

  That is, in one semiconductor integrated circuit 77, by setting the clock controller 86 to supply the operation clock CL1 to the printer control CPU 90, the printer control CPU 90 supplies the operation clock CL1 when the print image is formed. It has been set to work in response.

  In one semiconductor integrated circuit 77, by operating the setting terminal 80, the command selector 94 is selected in the printer control section 75, and the control command C1 output from its own printer control CPU 90 is selected for supply to each section. It is set.

  Further, in one semiconductor integrated circuit 77, by operating the setting terminal 80, the transmission timing control unit 102 supplies the trigger selector 115 and the first count start trigger data D 11 output from the count start trigger register 111 to the counter 105. Is set to select as.

  On the other hand, the other semiconductor integrated circuit 78 of the two semiconductor integrated circuits 77 and 78 is operated so that the setting terminal 81 functions as the slave of the printer control unit 76 when the color printer 1 is manufactured, for example. Yes.

  Therefore, in the other semiconductor integrated circuit 78, the clock controller 87 supplies the operation clock CL2 generated by the PLL 85 to the image processing unit 83 by operating the setting terminal 81, and the printer controller 76 excludes the printer control CPU 91. It is set to supply to.

  That is, in the other semiconductor integrated circuit 78, the clock control unit 87 is set so as not to supply the operation clock CL2 to the printer control CPU 91, so that the printer control CPU 91 does not operate when the print image is formed. doing.

  In the other semiconductor integrated circuit 78, by operating the setting terminal 81, the printer control unit 76 selects the command selector 95 to supply the control command C1 output from the other printer control CPU 90 to its own unit. It is set as follows.

  In the other semiconductor integrated circuit 78, the trigger selector 116 is selected in the transmission timing control unit 103 by the operation on the setting terminal 81, and the second count start trigger data D 12 output from the sample circuit 114 is selected for supply to the counter 106. It is set to do.

  Thus, in the color printer 1, the printer control unit 75 of one semiconductor integrated circuit 77 is set to function as a master that controls the printer control unit 76 of the other semiconductor integrated circuit 78.

  In the color printer 1, the printer control unit 76 of the other semiconductor integrated circuit 78 is set to function as a slave controlled by the printer control unit 75 of the one semiconductor integrated circuit 77.

  In the following description, one of the two semiconductor integrated circuits 77 and 78, which is set so that the printer control unit 75 functions as a master, is also referred to as a master-side semiconductor integrated circuit 77. The other semiconductor integrated circuit 78 set so that the control unit 76 functions as a slave is also referred to as a slave-side semiconductor integrated circuit 78.

  In the following description, the printer control unit 75 provided in the master-side semiconductor integrated circuit 77 (that is, the printer control unit 75 set to function as a master) is also referred to as a master-side printer control unit 75.

  Furthermore, in the following description, the printer control unit 76 provided in the slave-side semiconductor integrated circuit 78 (that is, the printer control unit 76 set to function as a slave) is also referred to as a slave-side printer control unit 76.

  In the master-side semiconductor integrated circuit 77, for example, the four first to fourth exposure heads 25 to 28 are electrically connected to the head controller 100 of the master-side printer controller 75 via about 20 external terminals. It is connected to the.

  In the master-side semiconductor integrated circuit 77, for example, the motor 97 and the sensor 65 are electrically connected to the drive system controller 98 of the master-side printer controller 75 via several external terminals.

  Therefore, in the slave-side semiconductor integrated circuit 78, for example, the remaining one fifth exposure head 29 is electrically connected to the head controller 101 of the slave-side printer controller 76 via about 20 external terminals. Yes.

  In the slave-side semiconductor integrated circuit 78, for example, no motor or sensor is connected to the drive system controller 99 of the slave-side printer controller 76.

  By the way, in the color printer 1, the first to fifth sending timings described above are, for example, the distance between the passing presence / absence detection position and the first to fifth transfer execution positions that are sequentially adjacent along the transport direction, and the recording paper 5. Based on the conveyance speed and the like, it is appropriately selected as a predetermined time interval timing before the recording paper 5 is conveyed to the transfer unit 15 and before the first to fifth transfer execution positions are sequentially reached.

  Incidentally, the distance between the passage presence / absence detection position and the first transfer execution position is the distance between the passage presence / absence detection position and the first to fifth transfer execution positions that are sequentially adjacent along the transport direction. It is also the distance between the position and the center of the first photosensitive drum 20.

  The distance between the first transfer execution position and the second transfer execution position is also the distance between the centers of the first photosensitive drum 20 and the second photosensitive drum 21, and the second transfer execution position and the third transfer execution position. Is the distance between the centers of the second photosensitive drum 21 and the third photosensitive drum 22.

  Furthermore, the distance between the third transfer execution position and the fourth transfer execution position is also the distance between the centers of the third photosensitive drum 22 and the fourth photosensitive drum 23, and the fourth transfer execution position and the fifth transfer execution position are Is also the distance between the centers of the fourth photosensitive drum 23 and the fifth photosensitive drum 24.

  Actually, the first delivery timing is such that, for example, the recording paper 5 passes through the detection position so that the black toner image can be transferred from the time when the recording paper 5 conveyed to the transfer unit 15 reaches the first transfer execution position. And the first transfer execution position is selected as a timing at which the first image forming unit 10 reaches a predetermined first image forming start position for starting the toner image formation.

  The second delivery timing is such that the recording paper 5 is transferred to the first transfer execution position so that the yellow toner image can be transferred from the time when the recording paper 5 conveyed to the transfer unit 15 reaches the second transfer execution position. And the second transfer execution position is selected as a timing to reach a predetermined second image formation start position for causing the second image forming unit 11 to start forming a toner image.

  Further, for example, the recording paper 5 is moved to the second transfer execution position so that the magenta toner image can be transferred from the time when the recording paper 5 conveyed to the transfer unit 15 reaches the third transfer execution position. And the third transfer execution position is selected as a timing at which the third image forming unit 12 reaches a predetermined third image formation start position for starting the toner image formation.

  Further, for example, the recording paper 5 is moved to the third transfer execution position so that the cyan toner image can be transferred from the time when the recording paper 5 conveyed to the transfer unit 15 reaches the fourth transfer execution position. And the fourth transfer execution position is selected as a timing to reach a predetermined fourth image formation start position for causing the fourth image forming unit 13 to start forming a toner image.

  Further, for example, the recording paper 5 is moved to the fourth transfer execution position so that the clear toner image can be transferred from the time when the recording paper 5 conveyed to the transfer unit 15 reaches the fifth transfer execution position. And the fifth transfer execution position is selected as a timing at which the fifth image forming unit 14 reaches a predetermined fifth image formation start position for starting the toner image formation.

  In addition, in the color printer 1, the first to fifth timing information described above is generated so that the first to fifth sending timings are represented by count values counted by the counters 105 and 106, for example.

  That is, the first timing information indicates the first delivery timing, for example, from when the recording paper 5 conveyed to the transfer unit 15 at a predetermined conveyance speed reaches the passage presence / absence detection position until it reaches the first image formation start position. It is generated so as to be represented by a count value counted by the counters 105 and 106 in between.

  The second timing information indicates the second delivery timing, for example, from when the recording paper 5 conveyed to the transfer unit 15 at a predetermined conveyance speed reaches the second image formation start position after reaching the first image formation start position. It is generated so as to be represented by a count value counted by the counters 105 and 106.

  Further, the third timing information indicates the third delivery timing, for example, from when the recording sheet 5 conveyed to the transfer unit 15 at a predetermined conveyance speed reaches the second image formation start position until it reaches the third image formation start position. It is generated so as to be represented by a count value counted by the counters 105 and 106.

  Further, the fourth timing information includes the fourth delivery timing, for example, from when the recording paper 5 conveyed to the transfer unit 15 at a predetermined conveyance speed reaches the fourth image formation start position after reaching the third image formation start position. It is generated so as to be represented by a count value counted by the counters 105 and 106.

  Further, the fifth timing information includes the fifth delivery timing, for example, from when the recording paper 5 conveyed to the transfer unit 15 at a predetermined conveyance speed reaches the fourth image formation start position until it reaches the fifth image formation start position. It is generated so as to be represented by a count value counted by the counters 105 and 106.

  In the master-side semiconductor integrated circuit 77, the first to fourth timing information generated in this way is stored in advance in the timing information storage register 107.

  In the slave-side semiconductor integrated circuit 78, the timing information storage register 108 stores the fifth timing information generated in this way in advance.

  With this configuration, the image processing CPU 74 communicates print instruction data D15 described in a page description language such as PDL (Page Description Language), which is transmitted from the host device 70 when a print image is formed. The data is taken in via the unit 72 and temporarily stored in a RAM (Random Access Memory) 120.

  Further, the image processing CPU 74 reads the print instruction data D15 from the RAM 120, and generates image data D16 that represents a color image to be printed in a predetermined color space based on the print instruction data D15.

  Then, the image processing CPU 74 sends the image data D16 to the master side semiconductor integrated circuit 77 and the slave side semiconductor integrated circuit 78.

  At this time, the master side semiconductor integrated circuit 77 generates the operation clock CL1 by the PLL 84, and includes the image processing unit 82 by the clock control unit 86 and the CPU 90 for printer control of the master side printer control unit 75. Supply to each part.

  As a result, in the master-side semiconductor integrated circuit 77, the image processing unit 82 and the units including the printer control CPU 90 of the master-side printer control unit 75 operate according to the operation clock CL1.

  Therefore, when the image data D16 is given from the image processing CPU 74, the master side semiconductor integrated circuit 77 takes the image data D16 into the image processing unit 82.

  In the master-side semiconductor integrated circuit 77, under the control of the image processing CPU 74, the image processing unit 82 converts the image data D16 into printing data that represents a color image to be printed in a printing color space.

  Then, in the master-side semiconductor integrated circuit 77, the image processing unit 82 obtains four types of print color data D17 to D20 representing black, yellow, magenta, and cyan color components of the color image to be printed included in the print data. Then, the data is sent to a DRAM (Dynamic Random Access Memory) 121 provided outside the master side semiconductor integrated circuit 77 and temporarily stored.

  In the following description, the print color data D17 representing the black color component of the color image to be printed is also called first print color data D17, and the print color data representing the yellow color component of the color image to be printed. D18 is also referred to as second print color data D18.

  In the following description, the print color data D19 representing the magenta color component of the color image to be printed is also referred to as third print color data D19, and the print color data representing the cyan color component of the color image to be printed. D20 is also referred to as fourth print color data D20.

  On the other hand, the slave-side semiconductor integrated circuit 78 generates the operation clock CL2 by the PLL 85 at this time, and the clock control unit 87 generates the operation clock CL2 for printer control of the image processing unit 83 and the slave-side printer control unit 76. It supplies to each part except CPU91.

  As a result, in the slave-side semiconductor integrated circuit 78, the image processing unit 83 and the units other than the printer control CPU 91 of the slave-side printer control unit 76 operate according to the operation clock CL2.

  Therefore, when the image data D16 is given from the image processing CPU 74, the slave-side semiconductor integrated circuit 78 takes the image data D16 into the image processing unit 83.

  In the slave side semiconductor integrated circuit 78, the image processing unit 83 prints the image data D16 and the color image to be printed under the control of the image processing CPU 74 in the same manner as the image processing unit 82 of the master side semiconductor integrated circuit 77. Is converted to print data expressed in the color space.

  In the slave-side semiconductor integrated circuit 78, the image processing unit 83, for example, based on any one of the first to fourth print color data D17 to D20 included in the print data, the one first to fourth print. By changing the color component represented by the color data D17 to D20 to clear the special color, print color data (hereinafter also referred to as fifth print color data) D21 representing the clear is generated.

  That is, in the slave-side semiconductor integrated circuit 78, the image processing unit 83 has the same shape as the toner image formed according to any one of the first to fourth print color data D17 to D20, and the toner image Fifth print color data D21 for forming a clear toner image to be superimposed is generated.

  In the slave-side semiconductor integrated circuit 78, the image processing unit 83 sends the fifth print color data D21 to the DRAM 122 provided outside the slave-side semiconductor integrated circuit 78 and temporarily stores it.

  By the way, in this case, the printer control CPU 90 in the master side printer control section 75 operates in accordance with the operation clock CL1 when the operation clock CL1 is supplied as described above.

  In this case, the printer control CPU 91 in the slave side printer control unit 76 is not operating at all because the operation clock CL2 is not supplied as described above.

  Accordingly, the printer control CPU 90 in the master side printer control unit 75 appropriately generates a control command C1 for controlling each unit of the master side printer control unit 75 and sends it to these units via the command selector 94. The respective units are controlled based on the control command C1.

  Further, in the master side printer control unit 75, the printer control CPU 90 also appropriately generates a control command C1 for controlling each part of the slave side printer control unit 76, and sequentially passes through the command selector 94 and the external access control unit 92, and the slave side semiconductor. To the integrated circuit 78.

  For this reason, in the slave-side semiconductor integrated circuit 78, the slave-side printer control unit 76 receives the control command C <b> 1 transmitted from the master-side printer control unit 75 by the external access control unit 93.

  In the slave-side semiconductor integrated circuit 78, the slave-side printer control unit 76 sends the control command C1 received by the external access control unit 93 to each unit of the slave-side printer control unit 76 via the command selector 95.

  Therefore, in the master side printer control unit 75, the printer control CPU 90 controls each part of the slave side printer control unit 76 based on the control command C1.

  As a result, in the master-side printer control unit 75, the drive system control unit 98 operates the motor 97, and the first to fifth photosensitive drums 20 to 24 of the first to fifth image forming units 10 to 14 as described above. The first to fifth charging rollers, the first to fifth developing rollers, and the first to fifth supply rollers are rotated in one rotation direction or another rotation direction.

  In the master-side printer control unit 75, the drive system control unit 98 rotates the transfer belt 37 in the other rotation direction in the transfer unit 15, and in the fixing unit 16, the heat generating roller 46 and the pressure roller 47 are rotated in a direction opposite to each other. And rotate in the other direction of rotation.

  Further, in the master side printer controller 75, the drive system controller 98 includes a pair of recording paper transport rollers 52 and 53, a pair of recording paper transport rollers 54 and 55, a pair of recording paper transport rollers 60 and 61, and a pair of recording paper discharge. The rollers 62 and 63 are rotated in one rotation direction or the other rotation direction for conveying the recording paper 5.

  In addition, in the master side printer control unit 75, the drive system control unit 98 rotates the pair of recording sheet feeding rollers 50 and 51 in the other rotation direction for feeding the recording sheet 5, and removes the recording sheet 5 from the recording sheet cassette 6. It is fed to the transfer unit 15 through the feeding and feeding path 56.

  In the master-side printer control unit 75, the drive system control unit 98 operates the sensor 65. As a result, the printer control CPU 90 in the master side printer control unit 75 monitors whether or not the recording paper 5 conveyed to the transfer unit 15 has reached the passage presence / absence detection position via the sensor 65.

  As a result, when the master-side printer control unit 75 detects that the recording paper 5 has reached the passage presence / absence detection position, the master-side printer control unit 75 controls the count start trigger register 111 at that time to count the counter 105. Instruct start.

  In the transmission timing control unit 102 of the master side printer control unit 75, the count start trigger register 111 outputs the first count start trigger data D11 having a logic “L” level from the start of the operation of the master side printer control unit 75, for example. And sent to the counter 105 via the trigger selector 115.

  When the master side printer control unit 75 controls the count start trigger register 111 to instruct the counter 105 to start counting by the printer control CPU 90, the first count sent to the counter 105 at that time point. The start trigger data D11 is raised from the logic “L” level to the logic “H” level.

  In this way, the count start trigger register 111 instructs the counter 105 to start counting when the first count start trigger data D11 rises from the logic “L” level to the logic “H” level.

  Therefore, in the master-side printer control unit 75, the counter 105 starts counting when the first count start trigger data D11 supplied from the count start trigger register 111 rises from the logic “L” level to the logic “H” level. .

  When the counter 105 in the master-side printer control unit 75 starts counting, the counter 105 notifies the timing notification unit 109 of the counted value every time the count value is counted up (that is, incremented) in synchronization with the operation clock CL1. To do.

  In the master-side printer control unit 75, for example, the timing notification unit 109 performs head control on the first to fourth transmission timing notification data D6 to D9 of logic “L” level from the start of the operation of the master-side printer control unit 75, for example. The data is sent to the unit 100.

  At this time, the timing notification unit 109 in the master-side printer control unit 75 performs processing of the transmission timing control unit 102 of the slave-side printer control unit 76 for processing of the fourth transmission timing notification data D9. Is also transmitted to the slave-side printer control unit 76 as synchronization reference data D25 for referencing so as to synchronize as much as possible.

  In this state, the timing notification unit 109 in the master-side printer control unit 75 reads the first timing information from the timing information storage register 107 when the count value notification from the counter 105 is started.

  In the master-side printer control unit 75, the timing notification unit 109 compares the count values sequentially notified from the counter 105 with the count value indicated by the first timing information.

  As a result, when the count value notified from the counter 105 matches the count value indicated by the first timing information, the timing notification unit 109 in the master-side printer control unit 75 sends it to the head control unit 100 at that time. The first transmission timing notification data D6 is raised from the logic “L” level to the logic “H” level.

  Accordingly, the timing notification unit 109 notifies the head control unit 100 of the first transmission timing as the timing at which the first transmission timing notification data D6 is raised from the logic “L” level to the logic “H” level.

  In the master-side printer control unit 75, the timing notification unit 109 reads the second timing information from the timing information storage register 107 when the first transmission timing notification data D6 rises from the logic “L” level to the logic “H” level. .

  The timing notification unit 109 in the master-side printer control unit 75 calculates the first addition count value by adding the count value indicated by the first timing information to the count value indicated by the second timing information, for example, and sequentially from the counter 105. The notified count value is compared with the first addition count value.

  As a result, when the count value notified from the counter 105 matches the first addition count value, the timing notification unit 109 in the master-side printer control unit 75 sends the second value being sent to the head control unit 100 at that time. The transmission timing notification data D7 is raised from the logic “L” level to the logic “H” level.

  As a result, the timing notification unit 109 notifies the head control unit 100 of the second transmission timing as the timing at which the second transmission timing notification data D7 is raised from the logic “L” level to the logic “H” level.

  Further, in the master-side printer control unit 75, the timing notification unit 109 reads the third timing information from the timing information storage register 107 when the second transmission timing notification data D7 rises from the logic “L” level to the logic “H” level. .

  The timing notification unit 109 in the master side printer control unit 75 calculates the second addition count value by adding the first addition count value to the count value indicated by the third timing information, for example, and sequentially notifies the counter 105. The count value is compared with the second addition count value.

  As a result, when the count value notified from the counter 105 coincides with the second addition count value, the timing notification unit 109 in the master-side printer control unit 75 sends the third transmission sent to the head control unit 100 at that time. Timing notification data D8 rises from a logic “L” level to a logic “H” level.

  Thereby, the timing notification unit 109 notifies the head control unit 100 of the third transmission timing as the timing at which the third transmission timing notification data D8 is raised from the logic “L” level to the logic “H” level.

  Furthermore, in the master-side printer control unit 75, when the timing notification unit 109 raises the third transmission timing notification data D8 from the logic “L” level to the logic “H” level, the timing information storage register 107 outputs the fourth timing information. read out.

  The timing notification unit 109 in the master-side printer control unit 75 calculates the third addition count value by adding the second addition count value to the count value indicated by the fourth timing information, for example, and sequentially notifies the counter 105. The count value is compared with the third addition count value.

  As a result, when the count value notified from the counter 105 matches the third addition count value, the timing notification unit 109 in the master-side printer control unit 75 sends the fourth value being sent to the head control unit 100 at that time. The transmission timing notification data D9 is raised from the logic “L” level to the logic “H” level.

  Accordingly, the timing notification unit 109 notifies the head control unit 100 of the fourth transmission timing as the timing at which the fourth transmission timing notification data D9 is raised from the logic “L” level to the logic “H” level.

  At this time, the timing notification unit 109 in the master-side printer control unit 75 transmits the fourth transmission timing notification data D9 from the logic “L” level to the logic “H” level, thereby transmitting to the slave-side printer control unit 76. The synchronous reference data D25 being changed is also raised from the logic “L” level to the logic “H” level.

  As a result, the timing notification unit 109 notifies the slave-side printer control unit 76 of the fourth transmission timing as the timing when the synchronization reference data D26 rises from the logic “L” level to the logic “H” level.

  Incidentally, in the master side printer control unit 75, for example, when the conveyance of the recording paper 5 is started, the head control unit 100 requests the image processing unit 82 for the first to fourth print color data D17 to D20.

  In the master-side semiconductor integrated circuit 77, when the head control unit 100 requests the first to fourth print color data D17 to D20, the image processing unit 82 receives the first to fourth print color data D17 to D20 from the DRAM 121. Is read out and sent to the head controller 100.

  When the first to fourth print color data D17 to D20 are given from the image processing unit 82, the head control unit 100 in the master-side printer control unit 75 outputs the first print color data D17 and the first exposure head 25 individually. The first head control data D1 is converted to the above-described first head control data D1.

  In the master-side printer control unit 75, the head control unit 100 converts the second print color data D18 into the above-described second head control data D2 for individually controlling the second exposure head 26.

  Further, in the master-side printer controller 75, the head controller 100 converts the third print color data D19 into the above-described third head control data D3 for individually controlling the third exposure head 27.

  Further, in the master-side printer controller 75, the head controller 100 converts the fourth print color data D20 into the above-described fourth head control data D4 for individually controlling the fourth exposure head 28.

  In this state, in the master-side printer control unit 75, the head control unit 100 determines that the first transmission timing notification data D6 is logical among the first to fourth transmission timing notification data D6 to D9 given from the timing notification unit 109. When the first transmission timing is notified after rising from the “L” level to the logic “H” level, the first head control data D1 is transmitted to the first exposure head 25 at the notified first transmission timing.

  Further, in the master side printer control unit 75, the head control unit 100 causes the second transmission timing notification data D7 given from the timing notification unit 109 to rise from the logic “L” level to the logic “H” level, and the second transmission timing is set. When notified, the second head control data D2 is sent to the second exposure head 26 at the notified second sending timing.

  Further, in the master-side printer control unit 75, the head control unit 100 causes the third transmission timing notification data D8 given from the timing notification unit 109 to rise from the logic “L” level to the logic “H” level, and the third transmission timing is set. When notified, the third head control data D3 is transmitted to the third exposure head 27 at the notified third transmission timing.

  Furthermore, in the master side printer control unit 75, the head control unit 100 determines that the fourth transmission timing notification data D9 given from the timing notification unit 109 rises from the logic "L" level to the logic "H" level and the fourth transmission timing. Is sent, the fourth head control data D4 is sent to the fourth exposure head 28 at the notified fourth sending timing.

  On the other hand, in the sending timing control unit 103 of the slave side printer control unit 76, the sample circuit 114 receives the logic “L” level synchronous reference data D 25 transmitted from the master side printer control unit 75.

  In the slave-side printer control unit 76, the sample circuit 114 outputs the logic “L” level synchronization reference data D 25 as the above-described second count start trigger data D 12 and sends it to the counter 106 via the trigger selector 116. .

  Then, in the slave-side printer control unit 76, when the received synchronization reference data D25 rises from the logic “L” level to the logic “H” level in accordance with the fourth transmission timing, the sample circuit 114 stores the synchronization reference data D25. The rising edge to the logic “H” level is detected and synchronized with the operation clock CL2.

  Thus, in the slave-side printer control unit 76, the sample circuit 114 continues the synchronization reference data D25 synchronized with the operation clock CL2, and then starts the second count for instructing the counter 106 to start counting according to the fourth transmission timing. The trigger data D12 is sent to the counter 106 via the trigger selector 116.

  In this way, the sample circuit 114 instructs the counter 106 to start counting when the second count start trigger data D12 rises from the logic “L” level to the logic “H” level.

  Therefore, in the slave-side printer control unit 76, the counter 106 starts counting when the second count start trigger data D12 supplied from the sample circuit 114 rises from the logic “L” level to the logic “H” level.

  When the counter 106 in the slave-side printer control unit 76 starts counting, the counter 106 notifies the timing notification unit 110 of the counted value every time it counts up (that is, increments) in synchronization with the operation clock CL2. To do.

  In the slave-side printer control unit 76, the timing notification unit 110 sends, for example, the fifth transmission timing notification data D10 of the logic “L” level to the head control unit 101 from the start of the operation of the slave-side printer control unit 76. Yes.

  In this state, the timing notification unit 110 in the slave-side printer control unit 76 reads the fifth timing information from the timing information storage register 108 when notification of the count value from the counter 106 is started.

  Then, the timing notification unit 110 in the slave-side printer control unit 76 compares the count values sequentially notified from the counter 106 with the count value indicated by the fifth timing information.

  As a result, in the slave printer control unit 76, when the count value notified from the counter 106 matches the count value indicated by the fifth timing information, the timing notification unit 110 sends it to the head control unit 101 at that time. The fifth transmission timing notification data D10 is raised from the logic “L” level to the logic “H” level.

  Thereby, the timing notification unit 110 notifies the head control unit 101 of the fifth transmission timing as the timing at which the fifth transmission timing notification data D10 is raised from the logic “L” level to the logic “H” level.

  By the way, in the slave side printer control unit 76, the head control unit 101 requests the image processing unit 83 for the fifth print color data D21, for example, when the conveyance of the recording paper 5 is started.

  In the slave-side semiconductor integrated circuit 78, when the fifth print color data D 21 is requested from the head controller 101, the image processor 83 reads the fifth print color data D 21 from the DRAM 122 and sends it to the head controller 101. ing.

  In the slave-side printer control unit 76, when the fifth print color data D21 is given from the image processing unit 83, the head control unit 101 controls the fifth print color data D21 individually for the fifth exposure head 29. Are converted into the above-described fifth head control data D5.

  In this state, in the slave-side printer control unit 76, the head control unit 101 causes the fifth transmission timing notification data D10 provided from the timing notification unit 110 to rise from the logic “L” level to the logic “H” level and perform fifth transmission. When the timing is notified, the fifth head control data D5 is sent to the fifth exposure head 29 at the notified fifth sending timing.

  In this way, the master-side printer control unit 75 controls the transmission timing of the first to fifth head control data D1 to D5 to the first to fifth exposure heads 25 to 29 together with the slave-side printer control unit 76, and The first to fifth head control data D1 to D5 are sequentially sent to the first to fifth exposure heads 25 to 29, respectively.

  Incidentally, the master-side printer control unit 75 first detects that the recording paper 5 conveyed to the transfer unit 15 has reached the passage presence / absence detection position as described above when forming a print image.

  The master-side printer control unit 75 then applies the first to fourth exposure heads 25 to 28 located upstream in the transport direction of the recording paper 5 according to the timing when the recording paper 5 reaches the passage presence / absence detection position. The transmission timing of the first to fourth head control data D1 to D4 is controlled.

  As a result, the master-side printer control unit 75 sequentially sends the corresponding first to fourth head control data D1 to D4 to the first to fourth exposure heads 25 to 28 at substantially prescribed first to fourth sending timings. can do.

  The master-side printer control unit 75 uses the fourth transmission timing notification data D9 indicating the fourth transmission timing as the synchronous reference data D25, and the wiring board on which the master-side semiconductor integrated circuit 77 and the slave-side semiconductor integrated circuit 78 are mounted. Via the slave printer control unit 76.

  Then, the slave-side printer control unit 76 corresponds to the fourth sending timing indicated by the synchronization reference data D25 transmitted from the master-side printer control unit 75, and the fifth exposure head 29 located on the downstream side in the conveyance direction of the recording paper 5. The transmission timing of the fifth head control data D5 is controlled.

  However, the synchronization reference data D25 transmitted from the master-side printer control unit 75 to the slave-side printer control unit 76 via the wiring board has a very short delay during the transmission.

  The slave-side printer control unit 76 operates according to an operation clock CL2 that has the same frequency but is not synchronized with the operation clock CL1 of the master-side printer control unit 75.

  For this reason, when the slave-side printer control unit 76 synchronizes the synchronization reference data D25 with the operation clock CL2, the operation clock CL1 of the master-side printer control unit 75 uses, for example, 2 for the fourth transmission timing indicated by the synchronization reference data D25. An overhead of about a cycle occurs.

  Then, the slave-side printer control unit 76 controls the sending timing of the fifth head control data D5 in accordance with the fourth sending timing indicated by the synchronization reference data D25. The fifth head control data D5 is sent to the fifth exposure head 29 at a timing delayed by about a cycle.

  As a result, in the color printer 1, the clear toner image and the other color toner images on the surface of the recording paper 5 are caused by the shift of the fifth sending timing for sending the fifth head control data D5 to the fifth exposure head 29. Deviation occurs in the transfer position.

  However, in the color printer 1, the frequency of the operation clocks CL1 and CL2 of the master side printer control unit 75 and the slave side printer control unit 76 is assumed to be 200 [MHz], the print resolution is 1200 × 4800 dpi, and the print speed is 55 [ppm]. Then, the shift of the transfer position between the clear toner image and the other color toner image on the surface of the recording paper 5 is expressed by equation (1).

      2.7 [nm] = 25.4 [mm] / 4800 * (5 [ns] * 2 [cycle] * 0.01 / 20 [us]) (1)

As shown by the above, it is as small as about 2.7 [nm], which cannot be discerned by human eyes.

  Therefore, in the color printer 1, the master side printer control unit 75 and the slave side printer control unit 76 share the transmission timing of the first to fifth head control data D1 to D5 to the first to fifth exposure heads 25 to 29. Although controlled, the first to fifth exposure heads 25 to 29 can be controlled almost accurately to form a print image without deteriorating the print quality.

  In the case of this embodiment, in the color printer 1, for example, setting terminals 80 and 81 for causing the master-side semiconductor integrated circuit 77 and the slave-side semiconductor integrated circuit 78 to function as masters and slaves, command selectors 94 and 95, Although external access control units 92 and 93, sample circuits 113 and 114, and trigger selectors 115 and 116 are provided, other parts are configured in the same manner as a conventional semiconductor integrated circuit.

  In the color printer 1, for example, the master-side semiconductor integrated circuit 77 and the slave-side semiconductor integrated circuit 78 are provided with several external terminals for communicating with each other, but the number and use of other external terminals are different. This is similar to a conventional semiconductor integrated circuit.

In this way the color printer 1, the master-side semiconductor integrated circuit 77 and the slave-side semiconductor integrated circuit 78, as compared with the conventional semiconductor integrated circuit, the number of possible or external terminal to which the circuit scale significantly increases markedly increases that Thus, the circuit configuration and the number of external terminals are almost the same as those of the conventional semiconductor integrated circuit.

  In the color printer 1, when the five first to fifth image forming units 10 to 14 are provided as described above, the first to fifth colors corresponding to at least five colors are used as DRAMs used for image processing of the image data D16. It is necessary to prepare a capacity capable of storing the print color data D17 to D21.

  Therefore, in the color printer 1, the capacity of the DRAM 121 used for image processing by the image processing unit 82 of the master-side semiconductor integrated circuit 77 can store the first to fourth print color data D17 to D20 for four colors. The capacity is selected.

  In the color printer 1, the capacity of the DRAM 122 used for image processing by the image processing unit 83 of the slave-side semiconductor integrated circuit 78 is selected to a capacity that can store the fifth print color data D21 for one color. .

  Therefore, in the color printer 1, although two DRAMs 121 and 122 are provided as DRAMs used for image processing of the image data D16, first to fifth print color data D17 for five colors necessary for image processing are provided. Compared with the case where one DRAM having a capacity capable of storing D21 to D21 is provided, an increase in cost is avoided.

  Since the color printer 1 is provided with the two DRAMs 121 and 122 for image processing of the image data D16 as described above, the head control units 100 and 101 acquire the first to fifth print color data D17 to D21. Thus, it is possible to prevent the reading accesses of the first to fifth print color data D17 to D21 from being concentrated on the DRAMs 121 and 122.

  Therefore, although the color printer 1 has one more image forming unit than the conventional color printer, the read access of the first to fifth print color data D17 to D21 to the DRAMs 121 and 122 is concentrated and printing is performed. A decrease in performance can be avoided.

(1-3) Sending Timing Control Processing Next, using the timing chart shown in FIG. 5, the printer control CPU 90 of the master side printer control unit 75 causes the master side printer control unit 75 and the slave side printer control unit 76 to A sending timing control process for controlling the sending timing of the first to fifth head control data D1 to D5 to the first to fifth exposure heads 25 to 29 will be described.

  First, the master-side printer control unit 75 operates in accordance with the operation clock CL1 generated by the PLL 84 when a print image is formed (FIG. 5A).

  At this time, the slave-side printer control unit 76 operates in accordance with the operation clock CL2 generated by the PLL 85 except for the printer control CPU 91 (FIG. 5I).

  In this state, the printer control CPU 90 of the master-side printer control unit 75 conveys the recording paper 5 to the transfer unit 15 and detects that the recording paper 5 has reached the passage presence / absence detection position at time T1. 111, the first count start trigger data D11 is raised from the logic “L” level to the logic “H” level for an instruction to start counting (FIG. 5B), and the counter 105 is set via the trigger selector 115. (FIG. 5C).

  As a result, the printer control CPU 90 of the master side printer control unit 75 causes the counter 105 to start counting at the time point T1 and sequentially notifies the timing notification unit 109 of the counted value.

  Therefore, the printer control CPU 90 of the master side printer control unit 75 causes the timing notification unit 109 to compare the count value sequentially notified from the counter 105 with the count value indicated by the first timing information.

  As a result, when the timing notification unit 109 detects that the count value of the counter 105 matches the count value indicated by the first timing information, the printer control CPU 90 of the master-side printer control unit 75 detects that the count value of the counter 105 matches the count value indicated by the first timing information. The first transmission timing notification data D6 transmitted to the control unit 100 is raised from the logic “L” level to the logic “H” level for notification of the first transmission timing (FIG. 5D).

  Thus, the printer control CPU 90 of the master side printer control unit 75 notifies the head control unit 100 that the first transmission timing has arrived at the time T2, and the head control unit 100 receives the first control timing. The first head control data D1 can be sent to the first exposure head 25 at the sending timing.

  In addition, the printer control CPU 90 of the master side printer control unit 75 continues the count value sequentially notified from the counter 105 to the timing notification unit 109, the count value indicated by the first timing information, and the count value indicated by the second timing information. Are compared with the first addition count value that is the result of the addition.

  As a result, when the timing notification unit 109 detects that the count value of the counter 105 matches the first addition count value at time T3, the printer control CPU 90 of the master side printer control unit 75 detects the head control unit 100. The second transmission timing notification data D7 that is transmitted to is raised from the logic “L” level to the logic “H” level for notification of the second transmission timing (FIG. 5E).

  Accordingly, the printer control CPU 90 of the master side printer control unit 75 notifies the head control unit 100 that the second transmission timing has arrived at the time T3, and the head control unit 100 receives the second control timing. The second head control data D2 can be sent to the second exposure head 26 at the sending timing.

  Further, the printer control CPU 90 of the master-side printer control unit 75 adds the count value sequentially notified from the counter 105 to the timing notification unit 109 by the addition result of the first addition count value and the count value indicated by the third timing information. It is compared with a certain second addition count value.

  As a result, when the timing notification unit 109 detects that the count value of the counter 105 matches the second addition count value at the time T4, the printer control CPU 90 of the master side printer control unit 75 detects the head control unit 100. The third transmission timing notification data D8 that is transmitted to is raised from the logic “L” level to the logic “H” level for notification of the third transmission timing (FIG. 5F).

  Accordingly, the printer control CPU 90 of the master side printer control unit 75 notifies the head control unit 100 that the third sending timing has arrived at the time T4, and notifies the head control unit 100 of the third transmission timing. The third head control data D3 can be sent to the third exposure head 27 at the sending timing.

  Further, the printer control CPU 90 of the master side printer control unit 75 adds the count value sequentially notified from the counter 105 to the timing notification unit 109, and the addition result of the second addition count value and the count value indicated by the fourth timing information. The third addition count value is compared.

  As a result, when the timing notification unit 109 detects that the count value of the counter 105 matches the third addition count value at the time T5, the printer control CPU 90 of the master side printer control unit 75 detects the head control unit 100. The fourth transmission timing notification data D9 that is transmitted to is raised from the logic “L” level to the logic “H” level for notification of the fourth transmission timing (FIG. 5G).

  Accordingly, the printer control CPU 90 of the master side printer control unit 75 notifies the head control unit 100 that the fourth transmission timing has arrived at the time T5, and notifies the head control unit 100 of the fourth transmission timing. The fourth head control data D4 can be sent to the fourth exposure head 28 at the sending timing.

  By the way, the printer control CPU 90 of the master side printer control unit 75 at the time T5, the synchronous reference data D25 transmitted from the timing notification unit 109 to the slave side printer control unit 76 is also changed from the logical “L” level to the logical “ By rising to the “H” level (FIG. 5H), the sample circuit 114 of the slave-side printer control unit 76 is caused to receive the synchronous reference data D25 whose logic level has changed for notification of the fourth transmission timing.

  Then, the printer control CPU 90 of the master side printer control unit 75 gives the logic “H” of the synchronization reference data D25 at time T6 to the sample circuit 114 receiving the synchronization reference data D25 in the slave side printer control unit 76. The rising edge to the level is detected and synchronized with the operation clock CL2.

  As a result, the printer control CPU 90 of the master-side printer control unit 165 uses the synchronization reference data D25 as the second count start trigger data D12 that instructs the sample circuit 114 to start counting according to the fourth transmission timing (FIG. 5). (J)), it is sent to the counter 106 via the trigger selector 116 (FIG. 5 (K)).

  As a result, the printer control CPU 90 of the master side printer controller 75 causes the counter 106 to start counting at the slave side printer controller 76 at the time T6, and sequentially notifies the count notification unit 110 of the counted values.

  Therefore, the printer control CPU 90 of the master side printer control unit 75 causes the timing notification unit 110 in the slave side printer control unit 76 to compare the count value sequentially notified from the counter 106 with the count value indicated by the fifth timing information.

  As a result, the printer control CPU 90 of the master side printer control unit 75 determines that the count value of the counter 106 matches the count value indicated by the fifth timing information by the timing notification unit 110 of the slave side printer control unit 76 at time T7. Is detected, the fifth transmission timing notification data D10 transmitted to the head control unit 101 is raised from the logic “L” level to the logic “H” level for notification of the fifth transmission timing (FIG. 5). (L)).

  As a result, the printer control CPU 90 of the master side printer control unit 75 supplies the fifth head control data D5 to the head control unit 101 in the slave side printer control unit 76 at the time T7, that is, at a substantially specified fifth sending timing. It can be sent to the fifth exposure head 29.

  In this way, the printer control CPU 90 of the master-side printer control unit 75 supplies the first to fifth head control data corresponding to the first to fifth exposure heads 25 to 29 at substantially specified first to fifth sending timings. D1 to D5 can be sent sequentially.

(1-4) Operation and Effect of First Embodiment In the above configuration, in the color printer 1, the first to fifth exposure heads 25 to 29 are arranged from the upstream side to the downstream side in the conveyance direction of the recording paper 5. The five first to fifth image forming units 10 to 14 are sequentially arranged.

  The color printer 1 has printer control units 75 and 76, respectively, and two semiconductor integrated circuits 77 and 78 having the same configuration in which the maximum number of heads that can be connected is smaller than the total number of heads.

  In the color printer 1, the printer control unit 75 of one semiconductor integrated circuit 77 is set to function as a master, and the printer control unit 76 of the other semiconductor integrated circuit 78 is set to function as a slave. did.

  In the color printer 1, the four first to fourth exposure heads 25 to 28 are connected as control targets to the printer control unit 75 of the master-side semiconductor integrated circuit 77, and printer control of the slave-side semiconductor integrated circuit 78 is performed. One fifth exposure head 29 is connected to the unit 76 as a control target.

  In addition, when the print image is formed, the color printer 1 controls the sending timing of the first to fourth head control data D1 to D4 by the printer control unit 75 of the semiconductor integrated circuit 77 on the master side. The images are sequentially sent to the first to fourth exposure heads 25 to 28.

  Accordingly, the color printer 1 controls the first to fourth exposure heads 25 to 28 in the first to fourth image forming units 10 to 13 to sequentially start the formation of toner images.

  Further, the color printer 1 uses the printer timing of the slave-side semiconductor integrated circuit 78 to control the sending timing controlled for sending the fourth head control data D4 from the printer control unit 75 of the master-side semiconductor integrated circuit 77 to the fourth exposure head 28. The control unit 76 is notified.

  Then, the color printer 1 controls the transmission timing of the fifth head control data D5 by the printer control unit 76 of the semiconductor integrated circuit 78 on the slave side based on the notified transmission timing to control the fifth head control data. D5 is sent to the fifth exposure head 29.

  Thus, the color printer 1 starts the toner image formation by controlling the fifth exposure head 29 in the fifth image forming unit 14 at the fifth delivery timing.

  Therefore, even if the number of first to fifth exposure heads 25 to 29 to be controlled is increased as compared with the conventional color printer 1, all the first to fifth exposure heads 25 to 29 having the increased number are controlled. Two semiconductor integrated circuits in which the maximum number of heads that can be connected is less than the total number of heads without being controlled by a printer controller provided in one semiconductor integrated circuit to which the first to fifth exposure heads 25 to 29 can be connected. The first to fifth exposure heads 25 to 29 can be accurately controlled by the printer control units 75 and 76 of 77 and 78.

  Therefore, the color printer 1 can reduce the development cost of the semiconductor integrated circuits 77 and 78 having the printer control units 75 and 76 even if the number of the first to fifth exposure heads 25 to 29 to be controlled increases.

  The color printer 1 is provided with two semiconductor integrated circuits 77 and 78 in which the maximum number of heads that can be connected is the same as that of a conventional semiconductor integrated circuit and the circuit configuration and the number of external terminals are substantially the same as those of the conventional semiconductor integrated circuit. Therefore, the development cost of the two semiconductor integrated circuits 77 and 78 can be made substantially equal to the development cost when the conventional semiconductor integrated circuit is developed.

  According to the above configuration, the color printer 1 includes the five first to fifth exposure heads 25 to 29 used for forming the print image, the printer control unit 75 that can be set to function as a master and a slave, respectively. And two semiconductor integrated circuits 77 and 78 having a maximum head connectable number less than the total number of heads. The printer control unit 75 of the master side semiconductor integrated circuit 77 has a maximum number of head connectable. The first to fourth head control data D1 to D4 for the four first to fourth exposure heads 25 to 28 are sequentially sent to the first to fourth exposure heads 25 to 28 while controlling the sending timing, respectively. Then, the controlled transmission timing is notified to the printer control unit 76 of the semiconductor integrated circuit 78 on the slave side, and the printer control of the semiconductor integrated circuit 78 on the slave side is notified. Based on the notified sending timing, the unit 76 controls the sending timing of the fifth head control data D5 for the fifth exposure head 29 and sends the fifth head control data D5 to the fifth exposure head 29. I tried to do it.

  As a result, even if the number of the first to fifth exposure heads 25 to 29 to be controlled is increased as compared with the conventional case, the color printer 1 uses all the first to fifth exposure heads 25 to 29 whose number has been increased. Even if the first to fifth exposure heads 25 to 29 are not controlled by a printer control unit provided in one semiconductor integrated circuit, two semiconductors each having a maximum head connectable number smaller than the total number of heads. The first to fifth exposure heads 25 to 29 can be accurately controlled by the printer control unit of the integrated circuits 77 and 78. As a result, the development cost of the semiconductor integrated circuits 77 and 78 having the printer control unit is reduced. be able to.

  Therefore, although the color printer 1 increases the number of image forming units having exposure heads as compared with the conventional one, the development cost of the color printer 1 itself can be reduced by the amount that can reduce the development cost of the semiconductor integrated circuits 77 and 78. Can be made.

  The color printer 1 is provided with two semiconductor integrated circuits 77 and 78 having the same configuration. Therefore, although the color printer 1 is provided with two semiconductor integrated circuits 77 and 78, the development cost of the semiconductor integrated circuits 77 and 78 can be reduced by one, and the development cost of the semiconductor integrated circuits 77 and 78 can be further reduced. In addition, the development cost of the color printer 1 can be reduced.

  Further, the color printer 1 generates the semiconductor integrated circuit 77 of the two semiconductor integrated circuits 77 and 78 set so that the printer control unit 76 functions as a slave by the internal PLL 85 when the print image is formed. The operation clock CL2 is supplied to each unit except for the printer control CPU 91 so that the printer control CPU 91 is not operated.

  Therefore, the color printer 1 can reduce the power consumption of the semiconductor integrated circuit 78 on the slave side when forming a print image.

  Further, in the color printer 1, a DRAM 121 having a capacity capable of storing the first to fourth print color data D17 to D20 for four colors is provided for image processing of the image processing unit 82 of the master-side semiconductor integrated circuit 77. The DRAM 122 having a capacity capable of storing the fifth print color data D21 for one color is provided for image processing of the image processing unit 83 of the slave-side semiconductor integrated circuit 78.

  Therefore, although the color printer 1 is provided with two DRAMs 121 and 122 for image processing, a single DRAM having a capacity capable of storing first to fifth print color data D17 to D21 for five colors for image processing. It is possible to avoid an increase in cost as compared with the case of providing.

  In the color printer 1, by providing the two DRAMs 121 and 122 in this way, access for reading the first to fifth print color data D17 to D21 to the DRAMs 121 and 122 is concentrated, and the printing performance is deteriorated. This can also be avoided.

(2) Second Embodiment (2-1) Internal Configuration of Color Printer FIG. 6 in which the same reference numerals are assigned to corresponding parts in FIG. 1 shows a color printer 150 according to the second embodiment. The color printer 150 is configured similarly to the color printer 1 according to the first embodiment described above except for the configuration of the image forming unit 151.

  In this case, the image forming unit 151 includes, in addition to the four first to fourth image forming units 10 to 13, for example, one image forming unit (corresponding to white (W) representing the color component of the print image). Hereinafter, this is also referred to as a sixth image forming unit) 155.

  In other words, the image forming unit 151 sets the basic colors of black (K), yellow (Y), magenta (M), cyan (C), and white (W) to one color so as not to overlap each other. A total of five sixth and first to fourth image forming units 155 and 10 to 13 are used to form toner images.

  The sixth image forming unit 155 uses the first to fourth images except that the toner image is formed using a single color (that is, white) toner different from the other first to fourth image forming units 10 to 13. It is comprised similarly to the formation units 10 thru | or 13.

  That is, the sixth image forming unit 155 contains a photosensitive drum 156, an exposure head 157, a charging roller (not shown), a developing roller (not shown), a supply roller (not shown), and white toner. A toner cartridge (not shown) is provided.

  Incidentally, in the following description, the photosensitive drum 156, the exposure head 157, the charging roller, the developing roller, and the supply roller provided in the sixth image forming unit 155 correspond to the names of the sixth image forming unit 155, and the sixth. It is also called a photosensitive drum 156, a sixth exposure head 157, a sixth charging roller, a sixth developing roller, and a sixth supply roller.

  The sixth and first to fourth image forming units 155 and 10 to 13 are arranged at predetermined equal intervals from the upstream side to the downstream side in the conveyance direction of the recording paper 5. The unit 10, the second image forming unit 11, the third image forming unit 12, and the fourth image forming unit 13 are arranged in this order.

  That is, the sixth image forming unit 155 is arranged so as to press a part of the surface of the sixth photosensitive drum 156 against the first transfer execution position on the surface of the upper flat portion of the transfer belt 37.

  The first to fourth image forming units 10 to 13 are arranged at different positions from the case of the color printer 1 according to the first embodiment described above, and a part of the surface of the first to fourth photosensitive drums is transferred to the transfer belt. It is arranged so as to press against the second to fifth transfer execution positions on the surface of the upper flat portion of 37.

  Therefore, the color printer 150 conveys the recording paper 5 to the transfer unit 15 when forming a print image. However, when the color printer 150 detects that the recording paper 5 has reached the passage presence / absence detection position via the sensor 65, the color printer 150 responds accordingly. The sixth and first to fourth image forming units 155, 10 to 13 at the first to fifth sending timings at predetermined time intervals before the recording paper 5 sequentially reaches the first to fifth transfer execution positions. The head control data and the first to fourth head control data are sequentially sent to the sixth and first to fourth exposure heads 157 and 25 to 28.

  In the following description, the head control data sent to the sixth exposure head 157 is also referred to as sixth head control data in association with the name of the sixth exposure head 157.

  Accordingly, the sixth image forming unit 155 gives the sixth head control data to the sixth exposure head 157 before the recording paper 5 reaches the first transfer execution position of the transfer belt 37.

  In response to this, the sixth image forming unit 155 forms an electrostatic latent image on the surface of the sixth photosensitive drum 156 by the sixth exposure head 157 based on the sixth head control data, and white by the sixth developing roller. The electrostatic latent image is developed with the toner of and the toner image is started to be formed.

  Further, the first image forming unit 10 includes the first exposure head after the sixth image forming unit 155 starts forming the toner image and before the recording paper 5 reaches the second transfer execution position of the transfer belt 37. The first head control data is given to 25.

  In response to this, the first image forming unit 10 forms an electrostatic latent image on the surface of the first photosensitive drum 20 by the first exposure head 25 based on the first head control data, and also black by the first developing roller. The electrostatic latent image is developed with the toner of and the toner image is started to be formed.

  Further, the second image forming unit 11 includes a second exposure head after the first image forming unit 10 starts forming a toner image and before the recording paper 5 reaches the third transfer execution position of the transfer belt 37. The second head control data is given to 26.

  In response to this, the second image forming unit 11 forms an electrostatic latent image on the surface of the second photosensitive drum 21 by the second exposure head 26 based on the second head control data, and yellow by the second developing roller. The electrostatic latent image is developed with the toner of and the toner image is started to be formed.

  Further, the third image forming unit 12 includes a third exposure head after the second image forming unit 11 starts forming a toner image and before the recording paper 5 reaches the fourth transfer execution position of the transfer belt 37. The third head control data is given to 27.

  In response to this, the third image forming unit 12 forms an electrostatic latent image on the surface of the third photosensitive drum 22 by the third exposure head 27 based on the third head control data, and magenta by the third developing roller. The electrostatic latent image is developed with the toner of and the toner image is started to be formed.

  Furthermore, the fourth image forming unit 13 performs the fourth exposure after the third image forming unit 12 starts forming the toner image and before the recording paper 5 reaches the fifth transfer execution position of the transfer belt 37. Fourth head control data is given to the head 28.

  In response to this, the fourth image forming unit 13 forms an electrostatic latent image on the surface of the fourth photosensitive drum 23 by the fourth exposure head 28 based on the fourth head control data, and cyan by the fourth developing roller. The electrostatic latent image is developed with the toner of and the toner image is started to be formed.

  The color printer 150 receives the recording paper 5 conveyed to the transfer unit 15 by the transfer belt 37, and when the recording paper 5 reaches the first transfer execution position in the transfer unit 15, the transfer belt 37 and the sixth The white toner image formed on the surface of the sixth photosensitive drum 156 on the surface of the recording paper 5 while conveying the recording paper 5 sandwiched between the sixth photosensitive drum 156 of the image forming unit 155. Transcript.

  When the recording paper 5 reaches the second transfer execution position in the transfer unit 15, the color printer 150 sandwiches the recording paper 5 between the transfer belt 37 and the first photosensitive drum 20 of the first image forming unit 10. The black toner image formed on the surface of the first photosensitive drum 20 is transferred to the surface of the recording paper 5 while being conveyed.

  Further, when the recording paper 5 reaches the third transfer execution position in the transfer unit 15, the color printer 150 sandwiches the recording paper 5 between the transfer belt 37 and the second photosensitive drum 21 of the second image forming unit 11. The yellow toner image formed on the surface of the second photosensitive drum 21 is transferred to the surface of the recording paper 5 while being conveyed.

  Furthermore, when the recording paper 5 reaches the fourth transfer execution position in the transfer unit 15, the color printer 150 sandwiches the recording paper 5 between the transfer belt 37 and the third photosensitive drum 22 of the third image forming unit 12. The magenta toner image formed on the surface of the third photosensitive drum 22 is transferred to the surface of the recording paper 5 while being conveyed.

  Further, when the recording paper 5 reaches the fifth transfer execution position in the transfer unit 15, the color printer 150 sandwiches the recording paper 5 between the transfer belt 37 and the fourth photosensitive drum 23 of the fourth image forming unit 13. The cyan toner image formed on the surface of the fourth photosensitive drum 23 is transferred to the surface of the recording paper 5 while being conveyed.

  In this way, the color printer 150 continues the recording sheet 5 conveyed to the transfer unit 15 with the transfer belt 37 and the sixth and first to fourth image forming units 155 and 10 to 13. While being conveyed by the photosensitive drums 156, 20 to 23, toner images of five colors of white, black, yellow, magenta, and cyan can be transferred onto the surface of the recording paper 5 so as to be sequentially superimposed.

(2-2) Circuit Configuration of Color Printer Next, the circuit configuration of the color printer 150 will be described with reference to FIGS. 7 to 9 in which the same reference numerals are assigned to the corresponding parts as in FIGS.

  7 to 9, the color printer 150 includes an image processing CPU 74, an image processing CPU 160 having a different configuration from the master side semiconductor integrated circuit 77 and the slave side semiconductor integrated circuit 78, and two semiconductors having the same configuration. Except that the integrated circuits 161 and 162 are provided, the configuration is the same as that of the color printer 1 according to the first embodiment described above.

  The two semiconductor integrated circuits 161 and 162 are respectively provided with printer control units 165 and 166 that can control each unit of the color printer 150 for forming a print image (that is, circuits constituting the printer control units 165 and 166). A block is built in.)

  The two semiconductor integrated circuits 161 and 162 are the same as those in the first embodiment except that setting registers 170 and 171 are newly provided in the transmission timing control units 167 and 168 of the printer control units 165 and 166, respectively. The configuration is the same as that of the master side semiconductor integrated circuit 77 and the slave side semiconductor integrated circuit 78 according to the embodiment.

  With this configuration, one of the two semiconductor integrated circuits 161 and 162 is operated so that the setting terminal 80 functions as the master of the printer control unit 165 at the time of manufacturing the color printer 150, for example. Has been.

  On the other hand, the other semiconductor integrated circuit 162 of the two semiconductor integrated circuits 161 and 162 is operated such that, for example, the setting terminal 81 functions as the slave of the printer control unit 166 when the color printer 150 is manufactured. Yes.

  Thus, in the color printer 150, as in the case of the first embodiment described above, the printer control unit 165 of one semiconductor integrated circuit 161 serves as a master for controlling the printer control unit 166 of the other semiconductor integrated circuit 162. It is set to work.

  In the color printer 150, the printer control unit 166 of the other semiconductor integrated circuit 162 is set to function as a slave controlled by the printer control unit 165 of the one semiconductor integrated circuit 161.

  In the following description, one of the two semiconductor integrated circuits 161 and 162, one of the semiconductor integrated circuits 161 set so that the printer control unit 165 functions as a master, is also referred to as a master-side semiconductor integrated circuit 161. The other semiconductor integrated circuit 162 set so that the control unit 166 functions as a slave is also referred to as a slave-side semiconductor integrated circuit 162.

  In the following description, the printer control unit 165 provided in the master-side semiconductor integrated circuit 161 (that is, the printer control unit 165 set to function as a master) is also referred to as a master-side printer control unit 165.

  Furthermore, in the following description, the printer control unit 166 provided in the slave-side semiconductor integrated circuit 162 (that is, the printer control unit 166 set to function as a slave) is also referred to as a slave-side printer control unit 166.

  In the master-side semiconductor integrated circuit 161, for example, the four first to fourth exposure heads 25 to 28 are electrically connected to the head control unit 100 of the master-side printer control unit 165 via about 20 external terminals. It is connected to the.

  In the master-side semiconductor integrated circuit 161, for example, the motor 97 and the sensor 65 are electrically connected to the drive system controller 98 of the master-side printer controller 165 via several external terminals.

  Therefore, in the slave side semiconductor integrated circuit 162, for example, the remaining one sixth exposure head 157 is electrically connected to the head control unit 101 of the slave side printer control unit 166 via about 20 external terminals. Yes.

  In the slave-side semiconductor integrated circuit 162, for example, no motor or sensor is connected to the drive system control unit 99 of the slave-side printer control unit 166.

  Incidentally, in the color printer 150, as described above, the sixth image forming unit 155 is arranged on the upstream side in the conveyance direction of the recording paper 5 with respect to the first to fourth image forming units 10 to 13.

  Accordingly, the master-side printer control unit 165 and the slave-side printer control unit 166, when forming a print image, as described above, the sixth exposure head 157, the first exposure head 25, the second exposure head 26, the third exposure head 27, Corresponding sixth and first to fourth head control data D30, D1 to D4 need to be transmitted in the order of the fourth exposure head 28.

  That is, when forming a print image, first, the slave-side printer control unit 166 needs to send the sixth head control data D30 to the sixth exposure head 157 at the above-described first sending timing.

  Next, when the print image is formed, the master-side printer control unit 165 sends the first head control data D1 to the first exposure head 25 at the second sending timing described above, and then at the third sending timing mentioned above. It is necessary to send the second head control data D2 to the two exposure heads 26.

  Subsequently, when the print image is formed, the master-side printer control unit 165 sends the third head control data D3 to the third exposure head 27 at the fourth sending timing described above, and finally at the fifth sending timing mentioned above. The fourth head control data D4 needs to be sent to the fourth exposure head 28.

  Therefore, in the slave-side semiconductor integrated circuit 162, the timing notification unit 110 notifies the timing information storage register 108 of the transmission timing of the sixth head control data D30 to the head control unit 101 using the first transmission timing notification data D6 described above. In addition, the above-described first timing information is stored in advance.

  In the master-side semiconductor integrated circuit 161, the timing information storage register 107 includes a timing notification unit 109 that receives the first to fourth head control data in the second to fourth transmission timing notification data D7 to D10 described above. In order to notify the transmission timing of D1 to D4, the above-described second to fifth timing information is stored in advance.

  However, the slave side semiconductor integrated circuit 162 and the master side semiconductor integrated circuit 161 are provided with setting terminals 81 and 80 similar to those in the first embodiment described above.

  For this reason, in the slave-side semiconductor integrated circuit 162, the operation of the setting terminal 81 causes the trigger selector 116 to supply the trigger selector 116 and the second count start trigger data D12 output from the sample circuit 114 to the counter 106. Is set to select as.

  Further, in the master-side semiconductor integrated circuit 161, by operating the setting terminal 80, the transmission timing control unit 167 supplies the trigger selector 115 and the first count start trigger data D 11 output from the count start trigger register 111 to the counter 105. Is set to select as.

  That is, the master-side printer control unit 165 and the slave-side printer control unit 166 control the first to fifth sending timings by, for example, a timing control method that does not match the control order according to the master and slave settings. become.

  Accordingly, the master side printer control unit 165 and the slave side printer control unit 166 control the first to fifth sending timings by a timing control method that does not match the control order according to the master and slave settings. For example, setting registers 170 and 171 that can change the timing control method are provided together with some settings for functioning as a master and a slave.

  Actually, in the slave-side printer control unit 166, the setting register 171 selects the trigger selector 116 for supplying the first count start trigger data D11 output from the count start trigger register 112 to the counter 106 according to the firmware, for example. It has been reset as follows.

  In the master printer control unit 165, the setting register 170 resets the trigger selector 115 so as to select the second count start trigger data D <b> 12 output from the sample circuit 113 for supply to the counter 105.

  In addition to this, in the slave-side printer control unit 166, the setting register 171 causes the master-side printer control unit 165 to use the timing notification unit 110 as the first reference timing notification data D6 to be sent to the head control unit 101 as the synchronization reference data D31. Is set to send to.

  In the master side printer control unit 165, the setting register 170 receives the synchronization reference data D31 transmitted from the slave side printer control unit 166 by the sample circuit 113, and sends the second count start trigger data D12 to the trigger selector 115. It is set as follows.

  In this way, the master-side printer control unit 165 and the slave-side printer control unit 166 change the timing control method for the first to fifth sending timings so as to match the control order.

  With this configuration, the image processing CPU 160 transmits the print instruction data D15 transmitted from the host device 70 via the communication unit 72 in the same manner as in the first embodiment described above when the print image is formed. The image data D16 is generated based on the print instruction data D15.

  Then, the image processing CPU 160 sends the image data D16 to the image processing units 82 and 83 of the master side semiconductor integrated circuit 161 and the slave side semiconductor integrated circuit 162.

  At this time, in the master-side semiconductor integrated circuit 161, the image processing unit 82 performs the first to second operations based on the image data D16 under the control of the image processing CPU 160, as in the case of the first embodiment described above. Four print color data D17 to D20 are generated and temporarily stored in the DRAM 121.

  However, the image processing unit 83 in the slave-side semiconductor integrated circuit 162 is controlled by the image processing CPU 160 so as to be different from the case of the first embodiment described above.

  For this reason, in the slave-side semiconductor integrated circuit 162, the image processing unit 83 converts the image data D16 into print data under the control of the image processing CPU 160. For example, the image processing unit 83 includes the print data included in the print data. Print color data D32 representing the white color component of the color image is sent to the DRAM 122 and temporarily stored.

  Incidentally, in the following description, the print color data D32 representing the white color component of the color image to be printed included in the print data is also referred to as sixth print color data D32.

  Then, when the recording paper 5 is conveyed to the transfer unit 15, the printer control CPU 90 in the master side printer control unit 165 monitors whether or not the recording paper 5 has reached the passage presence / absence detection position via the sensor 65.

  As a result, in the master side printer control unit 165, when the printer control CPU 90 detects that the recording paper 5 has reached the passage presence / absence detection position, the printer control CPU 90 controls the count start trigger register 112 of the slave side printer control unit 166. Instruct 106 to start counting.

  In the transmission timing control unit 168 of the slave side printer control unit 166, the count start trigger register 112 outputs the first count start trigger data D11 having a logic “L” level from the start of the operation of the slave side printer control unit 166, for example. The data is sent to the counter 106 via the trigger selector 116.

  When the slave-side printer control unit 166 controls the count start trigger register 112 to instruct the counter 106 to start counting by the printer control CPU 90, the first count that is sent to the counter 106 at that time point. The start trigger data D11 is raised from the logic “L” level to the logic “H” level.

  In this way, the count start trigger register 112 instructs the counter 106 to start counting when the first count start trigger data D11 rises from the logic “L” level to the logic “H” level.

  Therefore, in the slave-side printer control unit 166, the counter 106 starts counting when the first count start trigger data D11 given from the count start trigger register 112 rises from the logic “L” level to the logic “H” level. .

  When the counter 106 in the slave-side printer control unit 166 starts counting, the counter 106 notifies the timing notification unit 110 of the counted value every time it counts up (that is, increments) in synchronization with the operation clock CL2. To do.

  In the slave-side printer control unit 166, for example, the timing notification unit 110 sends the first transmission timing notification data D6 of the logic “L” level to the head control unit 101 from the start of the operation of the slave-side printer control unit 166. Yes.

  At this time, in the slave side printer control unit 166, the timing notification unit 110 converts the first transmission timing notification data D6 into processing of the transmission timing control unit 168 and processing of the transmission timing control unit 167 of the master side printer control unit 165. It is also transmitted to the master side printer control unit 165 as synchronization reference data D31 to be referred to so as to synchronize as much as possible.

  In this state, when the slave side printer control unit 166 starts to notify the count value from the counter 106, the timing notification unit 110 reads the first timing information from the timing information storage register 108.

  In the slave-side printer control unit 166, the timing notification unit 110 compares the count values sequentially notified from the counter 106 with the count value indicated by the first timing information.

  As a result, in the slave printer control unit 166, when the count value notified from the counter 106 matches the count value indicated by the first timing information, the timing notification unit 110 sends it to the head control unit 101 at that time. The first transmission timing notification data D6 is raised from the logic “L” level to the logic “H” level.

  At this time, the timing notification unit 110 in the slave-side printer control unit 166 transmits the first transmission timing notification data D6 from the logic “L” level to the logic “H” level, thereby transmitting to the master-side printer control unit 165. The synchronous reference data D31 that has been changed also changes from the logic “L” level to the logic “H” level for notification of the first transmission timing.

  Accordingly, the timing notification unit 110 notifies the master-side printer control unit 165 of the first transmission timing as the rising timing of the synchronization reference data D31 from the logic “L” level to the logic “H” level.

  Meanwhile, in the slave-side printer control unit 166, for example, when the conveyance of the recording paper 5 is started, the head control unit 101 requests the image processing unit 83 for the sixth print color data D32.

  In the slave-side semiconductor integrated circuit 162, when the sixth print color data D 32 is requested from the head controller 101, the image processor 83 reads the sixth print color data D 32 from the DRAM 122 and sends it to the head controller 101. ing.

  In the slave-side printer control unit 166, when the sixth print color data D32 is given from the image processing unit 83, the head control unit 101 controls the sixth print color data D32 individually for the sixth exposure head 157. Are converted into the above-described sixth head control data D30.

  In this state, in the slave-side printer control unit 166, the head control unit 101 causes the first transmission timing notification data D6 given from the timing notification unit 110 to rise from the logic “L” level to the logic “H” level and perform the first transmission. When the timing is notified, the sixth head control data D30 is sent to the sixth exposure head 157 at the notified first sending timing.

  On the other hand, in the transmission timing control unit 167 of the master side printer control unit 165, the sample circuit 113 receives the logical “L” level synchronous reference data D 31 transmitted from the slave side printer control unit 166.

  Further, in the master side printer control unit 165, the sample circuit 113 outputs the logic “L” level synchronization reference data D 31 as the above-described second count start trigger data D 12 and sends it to the counter 105 via the trigger selector 115. .

  Then, in the master-side printer control unit 165, when the received synchronization reference data D31 rises from the logic “L” level to the logic “H” level, the sample circuit 113 sets the synchronization reference data D31 to the logic “H” level. The rising edge is detected in synchronization with the operation clock CL1.

  Accordingly, in the master side printer control unit 165, the sample circuit 113 instructs the start of counting the synchronization reference data D31 synchronized with the operation clock CL1 in accordance with the first transmission timing at the rise to the logic “H” level. The second count start trigger data D12 is sent to the counter 105 via the trigger selector 115.

  Therefore, in the master-side printer control unit 165, the counter 105 starts counting when the second count start trigger data D12 supplied from the sample circuit 113 rises from the logic “L” level to the logic “H” level.

  When the counter 105 in the master-side printer control unit 165 starts counting, the counter 105 notifies the timing notification unit 109 of the counted value every time the count value is counted up (that is, incremented) in synchronization with the operation clock CL1. To do.

  In the master side printer control unit 165, for example, the timing notification unit 109 performs head control on the second to fifth sending timing notification data D7 to D10 of the logic “L” level from the start of the operation of the master side printer control unit 165, for example. The data is sent to the unit 100.

  In this state, the timing notification unit 109 in the master-side printer control unit 165 reads the second timing information from the timing information storage register 107 when the count value notification from the counter 105 is started.

  In the master-side printer control unit 165, the timing notification unit 109 compares the count values sequentially notified from the counter 105 with the count value indicated by the second timing information.

  As a result, in the master-side printer control unit 165, when the count value notified from the counter 105 matches the count value indicated by the second timing information, the timing notification unit 109 sends it to the head control unit 100 at that time. The second transmission timing notification data D7 is raised from the logic “L” level to the logic “H” level.

  As a result, the timing notification unit 109 notifies the head control unit 100 of the second transmission timing as the timing at which the second transmission timing notification data D7 is raised from the logic “L” level to the logic “H” level.

  In the master printer control unit 165, the timing notification unit 109 reads the third timing information from the timing information storage register 107 when the second transmission timing notification data D7 rises from the logic “L” level to the logic “H” level. .

  Then, the timing notification unit 109 in the master-side printer control unit 165 calculates the fifth addition count value by adding the count value indicated by the second timing information to the count value indicated by the third timing information, for example, and sequentially from the counter 105. The notified count value is compared with the fifth addition count value.

  As a result, in the master-side printer control unit 165, when the count value notified from the counter 105 matches the fifth addition count value, the timing notification unit 109 sends the third value being sent to the head control unit 100 at that time. The transmission timing notification data D8 is raised from the logic “L” level to the logic “H” level.

  Thereby, the timing notification unit 109 notifies the head control unit 100 of the third transmission timing as the timing at which the third transmission timing notification data D8 is raised from the logic “L” level to the logic “H” level.

  Further, in the master side printer control unit 165, the timing notification unit 109 reads the fourth timing information from the timing information storage register 107 when the third transmission timing notification data D8 rises from the logic “L” level to the logic “H” level. .

  The timing notification unit 109 in the master-side printer control unit 165 calculates the sixth addition count value by adding the fifth addition count value to the count value indicated by the fourth timing information, for example, and sequentially notifies the counter 105. The count value is compared with the sixth addition count value.

  As a result, when the count value notified from the counter 105 matches the sixth addition count value, the timing notification unit 109 in the master-side printer control unit 165 sends the fourth transmission to the head control unit 100 at that time. The timing notification data D9 is raised from the logic “L” level to the logic “H” level.

  Accordingly, the timing notification unit 109 notifies the head control unit 100 of the fourth transmission timing as the timing at which the fourth transmission timing notification data D9 is raised from the logic “L” level to the logic “H” level.

  Furthermore, in the master side printer control unit 165, when the timing notification unit 109 raises the fourth transmission timing notification data D9 from the logic “L” level to the logic “H” level, the timing information storage register 107 outputs the fifth timing information. read out.

  The timing notification unit 109 in the master-side printer control unit 165 calculates, for example, a seventh addition count value by adding the sixth addition count value to the count value indicated by the fifth timing information, and sequentially notifies the counter 105. The count value is compared with the seventh addition count value.

  As a result, in the master-side printer control unit 165, when the count value notified from the counter 105 matches the seventh addition count value, the timing notification unit 109 sends the fifth transmission being sent to the head control unit 100 at that time. The timing notification data D10 is raised from the logic “L” level to the logic “H” level.

  Accordingly, the timing notification unit 109 notifies the head control unit 100 of the fifth transmission timing as the timing at which the fifth transmission timing notification data D10 is raised from the logic “L” level to the logic “H” level.

  By the way, in the master side printer control unit 165, the head control unit 100 takes in the first to fourth print color data D17 to D20 from the image processing unit 82 as in the case of the first embodiment described above, and performs the first operation. Through the fourth head control data D1 through D4 are generated.

  In this state, in the master-side printer control unit 165, the head control unit 100 determines that the second transmission timing notification data D7 is logical among the second to fifth transmission timing notification data D7 to D10 given from the timing notification unit 109. When the second transmission timing is notified after rising from the “L” level to the logic “H” level, the first head control data D1 is transmitted to the first exposure head 25 at the notified second transmission timing.

  In the master-side printer control unit 165, the head control unit 100 causes the third transmission timing to rise from the logic “L” level to the logic “H” level when the third transmission timing notification data D8 given from the timing notification unit 109 rises. When notified, the second head control data D2 is sent to the second exposure head 26 at the notified third sending timing.

  Further, in the master side printer control unit 165, the head control unit 100 causes the fourth transmission timing notification data D9 supplied from the timing notification unit 109 to rise from the logic “L” level to the logic “H” level, and the fourth transmission timing is set. When notified, the third head control data D3 is transmitted to the third exposure head 27 at the notified fourth transmission timing.

  Furthermore, in the master-side printer control unit 165, the head control unit 100 causes the fifth sending timing when the fifth sending timing notification data D10 given from the timing notifying unit 109 rises from the logic “L” level to the logic “H” level. Is sent, the fourth head control data D4 is sent to the fourth exposure head 28 at the notified fifth sending timing.

  In this manner, the master side printer control unit 165, together with the slave side printer control unit 166, provides sixth and first to fourth head control data D30, D1 for the sixth and first to fourth exposure heads 157, 25 to 28. The sixth and first to fourth head control data D30 and D1 to D4 are sequentially sent to the sixth and first to fourth exposure heads 157 and 25 to 28 by controlling the sending timing of D to D4.

  Then, the slave-side printer control unit 166 detects the recording paper 5 according to the timing at which the master-side printer control unit 165 detects that the recording paper 5 conveyed to the transfer unit 15 has reached the passage presence / absence detection position. The transmission timing of the sixth head control data D30 to the sixth exposure head 157 located upstream in the transport direction is controlled.

  As a result, the slave-side printer control unit 166 can send the sixth head control data D30 to the sixth exposure head 157 at a substantially prescribed first sending timing.

  Also, the slave-side printer control unit 166 uses the first sending timing notification data D6 indicating the first sending timing as the synchronous reference data D31, and the wiring board on which the master-side semiconductor integrated circuit 161 and the slave-side semiconductor integrated circuit 162 are mounted. Via the master side printer control unit 165.

  Then, the master-side printer control unit 165 has first to fourth positions located on the downstream side in the conveyance direction of the recording paper 5 in accordance with the first sending timing indicated by the synchronization reference data D31 transmitted from the slave-side printer control unit 166. The transmission timing of the first to fourth head control data D1 to D4 to the exposure heads 25 to 28 is controlled.

  For this reason, when the master-side printer control unit 165 synchronizes the synchronous reference data D31 with the operation clock CL1, as in the case of the first embodiment described above, the master-side printer control unit 165 performs the first transmission timing indicated by the synchronous reference data D31. For example, the operation clock CL2 of the slave-side printer control unit 166 causes an overhead of about two cycles.

  However, the master-side printer control unit 165 controls the sending timing of the first to fourth head control data D1 to D4 according to the first sending timing indicated by the synchronization reference data D31 because the overhead is remarkably short. In addition, the first to fourth head control data D1 to D1 are sent to the first to fourth exposure heads 25 to 28 at substantially specified second to fifth transmission timings (that is, timing delayed by, for example, about two cycles with the operation clock CL2). D4 can be sent out.

  By the way, in the color printer 150, when the first to fourth head control data D1 to D4 are sent at a delay of, for example, about two cycles from the prescribed second to fifth sending timings with the operation clock CL2, the recording paper is recorded. On the surface 5, there is a shift in the transfer position between the white toner image and the other color toner images.

  However, in the color printer 150 as well, the white toner image on the surface of the recording paper 5 and other colors are the same as in the case of the first embodiment described above (that is, the same as in the case described above in the expression (1)). The transfer position deviation from the toner image is so small that it cannot be discerned by human eyes.

  Therefore, in the color printer 150 as well, the master side printer control unit 165 and the slave side printer control unit 166 use the sixth and first to fourth head control data D30 for the sixth and first to fourth exposure heads 157 and 25 to 28, respectively. Although the transmission timings of D1 to D4 are shared and controlled, the sixth and first to fourth exposure heads 157 and 25 to 28 are controlled almost accurately so that the print image does not deteriorate the print quality. Can be formed.

  In the case of this embodiment, the color printer 150 is provided with setting registers 170 and 171 in the master-side semiconductor integrated circuit 161 and the slave-side semiconductor integrated circuit 162, but the other parts are the first described above. The configuration is the same as that of the master side semiconductor integrated circuit 77 and the slave side semiconductor integrated circuit 78 according to the embodiment.

  Therefore, in the color printer 150, the master-side semiconductor integrated circuit 161 and the slave-side semiconductor integrated circuit 162 are prevented from significantly increasing the circuit scale and the number of external terminals as compared with the conventional semiconductor integrated circuit. Thus, it is formed so as to have a circuit configuration and the number of external terminals substantially equal to those of the conventional semiconductor integrated circuit.

(2-3) Sending Timing Control Processing Next, using the timing chart shown in FIG. 10, the printer control CPU 90 of the master side printer control unit 165 causes the master side printer control unit 165 and the slave side printer control unit 166 to 6 and the first to fourth exposure heads 157 and 25 to 28, the transmission timing control process for controlling the transmission timing of the sixth and first to fourth head control data D30 and D1 to D4 will be described.

  First, the master-side printer control unit 165 operates in accordance with the operation clock CL1 generated by the PLL 84 when a print image is formed (FIG. 10A).

  At this time, except for the printer control CPU 91, the slave-side printer control unit 166 operates in accordance with the operation clock CL2 generated by the PLL 85 (FIG. 10I).

  In this state, the printer-control CPU 90 of the master-side printer control unit 165 conveys the recording paper 5 to the transfer unit 15, and detects that the recording paper 5 has reached the passage presence / absence detection position at time T11. The count start trigger register 112 of the unit 166 is caused to raise the first count start trigger data D11 from the logic “L” level to the logic “H” level for an instruction to start counting (FIG. 10 (I)). The data is sent to the counter 106 via the trigger selector 116 (FIG. 10 (J)).

  As a result, the printer control CPU 90 of the master side printer control unit 165 causes the counter 106 to start counting at the slave side printer control unit 166 at the time T11 and sequentially notifies the timing notification unit 110 of the counted values.

  Therefore, the printer control CPU 90 of the master side printer control unit 165 causes the timing notification unit 110 in the slave side printer control unit 166 to compare the count value sequentially notified from the counter 106 with the count value indicated by the fifth timing information.

  As a result, the printer control CPU 90 of the master side printer control unit 165 confirms that the count value of the counter 106 matches the count value indicated by the first timing information by the timing notification unit 110 of the slave side printer control unit 166 at time T12. Is detected, the first transmission timing notification data D6 transmitted to the head controller 101 is raised from the logic “L” level to the logic “H” level for notification of the first transmission timing (FIG. 10). (K)).

  Accordingly, the printer control CPU 90 of the master side printer control unit 165 notifies the head control unit 101 of the slave side printer control unit 166 that the first sending timing has arrived at the time T11, and the head control. The unit 101 can send the sixth head control data D30 to the sixth exposure head 157 at the first sending timing.

  Meanwhile, the printer control CPU 90 of the master side printer control unit 165 notifies the first transmission timing of the synchronous reference data D31 that the timing notification unit 110 is transmitting to the master side printer control unit 165 at the time T11. For this reason, the synchronous reference data D31 whose logic level has been changed is received by the sample circuit 113 for notification of the first transmission timing by rising from the logic “L” level to the logic “H” level (FIG. 10L). Let

  Then, the printer control CPU 90 of the master side printer control unit 165 gives a rising edge to the logic “H” level of the synchronous reference data D31 at time T13 with respect to the sample circuit 113 receiving the synchronous reference data D31. It is detected and synchronized with the operation clock CL1.

  As a result, the printer control CPU 90 of the master-side printer control unit 165 uses the synchronization reference data D31 as the second count start trigger data D12 that instructs the sample circuit 113 to start counting according to the first transmission timing (FIG. 10). (B)), the data is sent to the counter 105 via the trigger selector 115 (FIG. 10C).

  As a result, the printer control CPU 90 of the master side printer control unit 165 causes the counter 105 to start counting at the time T13 and sequentially notifies the timing notification unit 109 of the counted value.

  Accordingly, the printer control CPU 90 of the master-side printer control unit 165 causes the timing notification unit 109 to compare the count values sequentially notified from the counter 105 with the count value indicated by the second timing information.

  As a result, when the timing notification unit 109 detects that the count value of the counter 105 matches the count value indicated by the second timing information at time T14, the printer control CPU 90 of the master-side printer control unit 165 detects the head control. The second transmission timing notification data D7 transmitted to the unit 100 is raised from the logic “L” level to the logic “H” level for notification of the second transmission timing (FIG. 10D).

  As a result, the printer control CPU 90 of the master side printer control unit 165 notifies the head control unit 100 that the second sending timing has arrived at the time T14, and notifies the head control unit 100 of the second transmission timing. The first head control data D1 can be sent to the first exposure head 25 at the sending timing.

  Further, the printer control CPU 90 of the master-side printer control unit 165 continues the count values sequentially notified from the counter 105 to the timing notification unit 109 with the count value indicated by the third timing information and the count value indicated by the second timing information. Are compared with the fifth addition count value, which is the result of the addition.

  As a result, when the timing notification unit 109 detects that the count value of the counter 105 matches the fifth addition count value at time T15, the printer control CPU 90 of the master side printer control unit 165 detects the head control unit 100. The third transmission timing notification data D8 that is transmitted to is raised from the logic “L” level to the logic “H” level for notification of the third transmission timing (FIG. 10E).

  Thus, the printer control CPU 90 of the master side printer control unit 165 notifies the head control unit 100 that the third sending timing has arrived at the time T15, and notifies the head control unit 100 of the third transmission timing. The second head control data D2 can be sent to the second exposure head 26 at the sending timing.

  Further, the printer control CPU 90 of the master-side printer control unit 165 adds the count value sequentially notified from the counter 105 to the timing notification unit 109 by the addition result of the fifth addition count value and the count value indicated by the fourth timing information. It is compared with a certain sixth addition count value.

  As a result, when the timing notification unit 109 detects that the count value of the counter 105 matches the sixth addition count value at time T16, the printer control CPU 90 of the master side printer control unit 165 detects the head control unit 100. The fourth transmission timing notification data D9 that is transmitted to is raised from the logic “L” level to the logic “H” level for notification of the fourth transmission timing (FIG. 10F).

  As a result, the printer control CPU 90 of the master side printer control unit 165 notifies the head control unit 100 that the fourth sending timing has arrived at the time T16, and notifies the head control unit 100 of the fourth transmission timing. The third head control data D3 can be sent to the third exposure head 27 at the sending timing.

  Furthermore, the printer control CPU 90 of the master-side printer control unit 165 adds the count value sequentially notified from the counter 105 to the timing notification unit 109 and the addition result of the sixth addition count value and the count value indicated by the fifth timing information. And the seventh addition count value.

  As a result, when the timing notification unit 109 detects that the count value of the counter 105 matches the seventh addition count value at time T17, the printer control CPU 90 of the master side printer control unit 165 detects the head control unit 100. The fifth transmission timing notification data D10 that is transmitted to is raised from the logic “L” level to the logic “H” level for notification of the fifth transmission timing (FIG. 10G).

  As a result, the printer control CPU 90 of the master side printer control unit 165 notifies the head control unit 100 that the fifth transmission timing has arrived at the time T17, and notifies the head control unit 100 of the fifth transmission timing. The fourth head control data D4 can be sent to the fourth exposure head 28 at the sending timing.

  In this way, the printer control CPU 90 of the master-side printer control unit 165 has the sixth and first exposure heads 157 and 25 to 28 corresponding to the sixth and first exposure heads 157 and 25 to 28 at substantially specified first to fifth sending timings. The first to fourth head control data D30 and D1 to D4 can be sent sequentially.

(2-4) Operation and Effect of Second Embodiment In the above configuration, in the color printer 150, the sixth and first to fourth exposure heads 157 move from the upstream side to the downstream side in the conveyance direction of the recording paper 5. , 25 to 28, the sixth and first to fourth image forming units 155, 10 to 13 are arranged in order.

  Further, the color printer 150 includes printer control units 165 and 166, respectively, and two semiconductor integrated circuits 161 and 162 having the same configuration in which the maximum number of heads that can be connected is smaller than the total number of heads.

  In the color printer 150, the printer control unit 165 of one semiconductor integrated circuit 161 is set to function as a master, and the printer control unit 166 of the other semiconductor integrated circuit 162 is set to function as a slave. did.

  In the color printer 150, the four first to fourth exposure heads 25 to 28 are connected as control targets to the printer control unit 165 of the master-side semiconductor integrated circuit 161, and the printer control of the slave-side semiconductor integrated circuit 162 is performed. One sixth exposure head 157 is connected to the unit 166 as a control target.

  Further, in the color printer 150, the settings for the printer control unit 165 of the master-side semiconductor integrated circuit 161 and the printer control unit 166 of the slave-side semiconductor integrated circuit 162 to function as a master and a slave are the sixth and first to first settings. Even when the first to fifth sending timings of the fourth head control data D30 and D1 to D4 are controlled by a timing control method that does not match the control order, the timing control method is changed to the control order. The setting registers 170 and 171 that can be changed to be suitable for the above are provided.

  Then, when forming the print image, the color printer 150 controls the sending timing of the sixth head control data D30 by the printer control unit 166 of the semiconductor integrated circuit 162 on the slave side, and sends the sixth head control data D30 to the sixth exposure. Send to head 157.

  As a result, the color printer 150 controls the sixth exposure head 157 in the sixth image forming unit 155 to start the toner image formation at the first sending timing.

  Further, the color printer 150 uses the printer timing of the master-side semiconductor integrated circuit 161 to control the sending timing controlled for sending the sixth head control data D30 from the printer control unit 166 of the slave-side semiconductor integrated circuit 162 to the sixth exposure head 157. Notify the control unit 165.

  The color printer 150 controls the sending timing of the first to fourth head control data D1 to D4 based on the notified sending timing by the printer control unit 165 of the master-side semiconductor integrated circuit 161. Are sequentially sent to the corresponding first to fourth exposure heads 25 to 28.

  As a result, the color printer 150 controls the first to fourth exposure heads 25 to 28 in the first to fourth image forming units 10 to 13 to sequentially start the formation of toner images.

  Therefore, even if the number of the sixth and first to fourth exposure heads 157 and 25 to 28 to be controlled is increased as compared with the conventional color printer 150, all the sixth and first to fourth exposure heads 157, The printer control unit of the two semiconductor integrated circuits 161 and 162 in which the maximum number of connectable heads is smaller than the total number of heads without being controlled by the printer control unit provided in one semiconductor integrated circuit to which 25 to 28 can be connected. The sixth and first to fourth exposure heads 157, 25 to 28 can be accurately controlled by 165 and 166, respectively.

  As a result, the color printer 150 can reduce the development cost of the semiconductor integrated circuits 161 and 162 having the printer control units 165 and 166.

  When the color printer 150 is set so that the printer control unit 165 of one semiconductor integrated circuit 161 functions as a master and the printer control unit 166 of the other semiconductor integrated circuit 162 is set to function as a slave, 6 and the first to fourth head control data D30 and D1 to D4, the first to fifth sending timings are controlled by a timing control method that does not match the control order. Thus, the timing control method can be changed.

  According to the above configuration, the color printer 150 includes the five sixth and first to fourth exposure heads 157 and 25 to 28 used for forming a print image, and functions as a master and a slave, respectively. The printer control units 165 and 166 that can be set, and the setting for functioning as a master and slave, the first to fifth sending timings of the sixth and first to fourth head control data D30 and D1 to D4 are set as follows: When control is performed using a timing control method that does not match the order of control, setting registers 170 and 171 that can change the timing control method are provided, and the maximum number of heads that can be connected is smaller than the total number of heads. The semiconductor integrated circuits 161 and 162 are provided by the printer control unit 166 of the slave side semiconductor integrated circuit 162. When the sixth head control data D30 is sent to the sixth exposure head 157 by controlling the sending timing, the printer control unit 165 of the master-side semiconductor integrated circuit 161 controls the first to first heads according to the controlled sending timing. The transmission timing of the fourth head control data D1 to D4 is controlled, and the first to fourth head control data D1 to D4 are sequentially transmitted to the first to fourth exposure heads 25 to 28.

  As a result, the color printer 150 can obtain the same effect as that obtained by the first embodiment described above, and in addition to this, in the setting of the master and the slave, the sixth and the first to the fourth. Even when the first to fifth transmission timings of the head control data D30 and D1 to D4 are controlled by a timing control method that does not match the control order, the timing control method is adapted to the control order. The plurality of exposure heads can be accurately controlled.

(3) Other embodiments (3-1) Other embodiments 1
In the first and second embodiments described above, the first to fifth image forming units 10 to 14, the sixth and first to fourth image forming units 155 and 10 are included in the color printers 1 and 150. The case where thru 13 are provided has been described.

  However, the present invention is not limited to this, and a color printer may be provided with 6 to 8 image forming units.

  According to the present invention, the color printer is provided with three or more semiconductor integrated circuits each capable of setting whether the printer control unit functions as a master or a slave, and according to this, nine or more image forming units are provided. You may do it.

The present invention, by the configuration according, it is possible to obtain the same effect as the effect obtained by the first and second embodiments described above.

(3-2) Other Embodiment 2
In the first and second embodiments described above, the four first to fourth exposure heads 25 to 16 are provided in the semiconductor integrated circuits 77 and 161 set so that the printer control units 75 and 165 function as masters. 28, and the fifth or sixth exposure heads 29, 157 are electrically connected to the semiconductor integrated circuits 78, 162 set so that the printer control units 76, 166 function as slaves. The case was described as above.

  However, the present invention is not limited to this, and three or less first to sixth exposure heads 25 to 29, 157 are provided in the semiconductor integrated circuits 77, 161 set so that the printer control units 75, 165 function as masters. At least two or more first to sixth exposure heads 25 to 29 and 157 are electrically connected to the semiconductor integrated circuits 78 and 162 which are electrically connected and set so that the printer control units 76 and 166 function as slaves. You may make it connect.

  The present invention can obtain the same effects as those obtained by the first and second embodiments described above even with such a configuration.

(3-3) Other Embodiment 3
Furthermore, in the first and second embodiments described above, the motor 97 and the sensor 65 are electrically connected to the semiconductor integrated circuits 77 and 161 set so that the printer control units 75 and 165 function as masters. The case where the motor and sensor are not connected to the semiconductor integrated circuits 78 and 162 set so that the printer control units 76 and 166 function as slaves has been described.

  However, the present invention is not limited to this, and the printer control units 76 and 166 can be connected to the semiconductor integrated circuits 77 and 161 set so that the printer control units 75 and 165 function as masters without connecting any motors and sensors. The motor 97 and the sensor 65 may be electrically connected to the semiconductor integrated circuits 78 and 162 set to function as slaves.

  In the present invention, one of the motor 97 and the sensor 65 is electrically connected to the semiconductor integrated circuits 77 and 161 set so that the printer control units 75 and 165 function as masters, and the printer control units 76 and 166 are slaves. The other of the motor 97 and the sensor 65 may be electrically connected to the semiconductor integrated circuits 78 and 162 set so as to function.

  Further, the present invention relates to semiconductor integrated circuits 77 and 161 in which the printer control units 75 and 165 are set to function as masters, and semiconductor integrated circuits 78 in which the printer control units 76 and 166 are set to function as slaves. The motor 97 may be distributed to 162 and electrically connected to each other, and the plurality of sensors 65 may also be distributed and electrically connected to each other.

  The present invention can obtain the same effects as those obtained by the first and second embodiments described above even with such a configuration.

(3-4) Other Embodiment 4
Further, in the first and second embodiments described above, a case has been described in which the color printers 1 and 150 are provided with two semiconductor integrated circuits 77, 78, 161 and 162 having the same configuration.

  However, the present invention is not limited to this, but the color printer has a configuration that can arbitrarily set whether the printer control unit functions as a master or a slave, but in other parts, for example, at least one of them It is also possible to provide at least two or more semiconductor integrated circuits having different configurations so that a drive control unit is provided in the other and no other one or more drive control units are provided.

  The present invention can obtain the same effects as those obtained by the first and second embodiments described above even with such a configuration.

  According to another aspect of the present invention, a color printer includes a semiconductor integrated circuit configured so that the printer control unit functions as a master in advance, and at least one or more configured so that the printer control unit functions as a slave in advance. A semiconductor integrated circuit may be provided.

  According to the present invention, for example, any semiconductor integrated circuit can be configured without providing a setting terminal, and at least one or more of the printer control unit configured to function as a slave in advance is provided. As for the semiconductor integrated circuit, the configuration of the semiconductor integrated circuit can be simplified, such as a configuration without providing a printer control CPU.

(3-5) Other Embodiment 5
Furthermore, in the first and second embodiments described above, two semiconductor integrated circuits 77, 78, 161, which are formed in the color printers 1, 150 with the maximum number of heads connectable being selected to 4, respectively. The case where 162 is provided has been described.

  However, the present invention is not limited to this, and in a color printer, each of the two semiconductor integrated circuits formed by selecting the maximum number of heads that can be connected to three, or the maximum number of heads that can be connected to each of which is selected to be two. At least three or more semiconductor integrated circuits formed in this manner, and at least two or more semiconductor integrated circuits formed by selecting different numbers of the maximum number of heads that can be connected to each other may be provided.

  The present invention can obtain the same effects as those obtained by the first and second embodiments described above also by these various configurations.

(3-6) Other Embodiment 6
Furthermore, in the first and second embodiments described above, the image forming apparatus according to the present invention is applied to the color printers 1 and 150 that perform multicolor printing by the tandem method described above with reference to FIGS. Said about the case.

  However, the present invention is not limited to this, and is widely applied to image forming apparatuses of various other configurations such as a color printer that performs multicolor printing in a cycle system, an ink jet printer, a multifunction printer, a facsimile machine, and a multifunction machine. can do.

(3-7) Other Embodiment 7
Further, in the first and second embodiments described above, the first to sixth exposure heads 25 to 29 and 157 described above with reference to FIGS. 1 to 10 are applied as a plurality of image forming heads. Stated.

  However, the present invention is not limited to this, and various other image forming heads can be widely applied, such as a printer head that discharges ink as a developer for forming a printed image.

(3-8) Other Embodiment 8
Furthermore, in the first and second embodiments described above, an image forming control unit that sends head control data by controlling the sending timing to image forming heads that are less than the maximum connectable number less than the total number of image forming heads. As described above, the master side printer control units 75 and 165 and the slave side printer control units 76 and 166 described above with reference to FIGS. 1 to 10 are applied.

  However, the present invention is not limited to this, like a printer control unit that sends head control data to a printer head that is less than the maximum number of connectable printer heads that are smaller than the total number of printer heads that eject ink. In addition, image forming control units having various configurations can be widely applied.

(3-9) Other Embodiment 9
Furthermore, in the first and second embodiments described above, the maximum number of connectable image forming heads is selected to be smaller than the total number of the image forming heads, and the image is equal to or less than the maximum connectable number of connected images. Master side semiconductor integrated circuits 77 and 161 and slave side semiconductor integrated circuits described above with reference to FIGS. 1 to 10 are used as a plurality of semiconductor integrated circuits having an image formation control unit for sending head control data by controlling the sending timing to the forming head. The case where the circuits 78 and 162 are applied has been described.

  However, the present invention is not limited to this, a semiconductor integrated circuit configured so that the printer control unit functions as a master in advance, and a plurality of semiconductor integrated circuits configured such that the printer control unit functions as a slave in advance, A semiconductor integrated circuit configured so that the printer control unit functions as a master in advance, a plurality of semiconductor integrated circuits that can arbitrarily set whether the printer control unit functions as a master or a slave, a printer control unit as a master, Various other configurations such as a plurality of semiconductor integrated circuits that can arbitrarily set which of them function as a slave, and a plurality of semiconductor integrated circuits configured so that the printer control unit functions as a slave in advance A plurality of combined semiconductor integrated circuits can be widely applied.

(3-10) Other Embodiment 10
Furthermore, in the first and second embodiments described above, when the setting registers 170 and 171 described above with reference to FIGS. 1 to 10 are applied as the control method changing unit that changes the timing control method of the transmission timing. Said.

  However, the present invention is not limited to this, and various other control method changing units such as the printer control CPUs 90 and 91 can be widely applied.

(3-11) Other Embodiment 11
Furthermore, in the first and second embodiments described above, the setting terminal described above with reference to FIGS. 1 to 10 is used as a setting unit that can arbitrarily set whether the image forming control unit functions as a master or a slave. The case where 80 and 81 are applied was described.

  However, the present invention is not limited to this, and various other setting units such as the printer control CPUs 90 and 91 can be widely applied.

(3-12) Other Embodiment 12
Further, in the first and second embodiments described above, the case where the printer control CPUs 90 and 91 described above with reference to FIGS. 1 to 10 are applied as the control unit for controlling the image forming control unit has been described. .

  However, the present invention is not limited to this, and a DSP (Digital Signal Processor), a microprocessor, or a printer control unit is set to function as a slave. Various other control units can be widely applied.

  The present invention can be used in image forming apparatuses such as a color printer that performs multicolor printing by a tandem method, a color printer that performs multicolor printing by a cycle method, an inkjet printer, a multifunction printer, a facsimile machine, and a multifunction peripheral.

  DESCRIPTION OF SYMBOLS 1,150 ... Color printer, 25 ... 1st exposure head, 26 ... 2nd exposure head, 27 ... 3rd exposure head, 28 ... 4th exposure head, 29 ... 5th exposure head, 75, 165... Master side printer controller, 76, 166... Slave side printer controller, 77, 161... Master side semiconductor integrated circuit, 78, 162... Slave side semiconductor integrated circuit, 90, 91. CPU, 100, 101... Head control unit, 102, 103, 167, 168... Sending timing control unit, 109, 110... Timing notification unit, 157... Sixth exposure head, 170, 171. D1: First head control data, D2: Second head control data, D3: Third head control data, D4: Fourth head control data, D5: F5 Control data, D6 ... first transmission timing notification data, D7 ... second transmission timing notification data, D8 ... third transmission timing notification data, D9 ... fourth transmission timing notification data, D10 ... fifth transmission Timing notification data, D30 ... sixth head control data, D25, D31 ... synchronous reference data.

Claims (4)

A plurality of image forming heads;
Connectable maximum number of the image forming heads each are formed by selecting less than the total number of the imaging head, controlled by the head control timing out sent to connected the connectable maximum number following the imaging head A plurality of semiconductor integrated circuits provided with an image formation control unit for sending data, the image formation control unit having a control method changing unit for changing the timing control method of the sending timing ,
Among the image forming control section provided for each of the plurality of the semiconductor integrated circuit, either the image forming control section provided in one of the semiconductor integrated circuit, the provided rest of the semiconductor integrated circuit functions as a master to control the image forming control unit, the remainder of the semiconductor integrated the image forming control section provided in the circuit, and functions as a slave that is controlled by the image forming control unit that functions as the master When the timing control method is not changed by the control method changing unit, when the image forming control unit controls the sending timing of the head control data sent to the image forming head, the other image forming control is performed. The image is sent to the image forming head in accordance with the sending timing controlled by any of the image forming control units. And controlling the transmission timing of the serial head control data, if you change the timing control method by the control method changing unit, the other of the image forming control unit, of the head control data to be transmitted to the image forming head above When the sending timing is controlled, the sending timing of the head control data to be sent to the image forming head is controlled by one of the image forming control units controlled by the other image forming control unit. An image forming apparatus to be controlled . The plurality of semiconductor integrated circuits are:
The image forming apparatus according to claim 1 , further comprising: a setting unit that can arbitrarily set whether the image forming control unit functions as the master or the slave. The plurality of semiconductor integrated circuits are:
The image forming apparatus according to claim 1 , wherein the image forming apparatus is formed to have the same configuration. The image formation control unit provided in each of the plurality of semiconductor integrated circuits,
The control unit of the image formation control unit having a control unit for controlling the image formation control unit and set to function as the master functions as the image formation control unit functioning as the master and the slave The image forming control unit according to any one of claims 1 to 3, wherein the control unit of the image forming control unit configured to control the image forming control unit configured to function as the slave stops operation. apparatus.

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