JP5117824B2 - LED printer and printing control method - Google Patents

Description

  The present invention relates to a control technique for an LED printer, and more particularly to a control technique for an LED printer using a split LED head.

  In the conventional LED printer printing process, an LED head provided against a photosensitive drum flashes and emits light (exposure) on the basis of print data supplied from the outside, thereby electrostatic latent images on the photosensitive drum. An image is formed and developed by supplying toner onto the electrostatic latent image formed on the photosensitive drum by the developing unit, and the toner image formed by the development is supplied to the paper supplied by the registration roller by the transfer unit This is done by transferring and adhering to the top.

  Thereafter, the fixing device discharges the paper and fixes the toner adhered on the paper to the paper, thereby completing the printing. The LED printer is controlled by a print control circuit.

  In particular, paper feeding in the printing process of the LED printer is performed by a photosensitive drum arranged at the center, a registration roller for feeding paper, and a fixing device for discharging paper. The sheet feeding speed between the registration roller and the fixing unit is constant, and the sheet feeding of the fixing unit is set to be faster with respect to the registration roller in order to feed the sheet stably.

  Therefore, the leading edge area where the paper is fed only by the registration roller before the paper reaches the fixing device, the central area where the paper is fed by both the fixing device and the registration roller, and the paper is separated from the registration roller. A phenomenon occurs in which the sheet feeding speed differs between the rear end area where the sheet is fed only by the fixing unit.

  Since the rotation speed of the photosensitive drum is normally set in accordance with the paper feed speed in the central area of the paper, sub-scanning is performed in the leading edge area and the trailing edge area of the paper with respect to the central area of the paper. In the direction, the length is not printed correctly.

  For example, as shown in FIG. 9A, when two parallel lines with an interval of a2 in the sub-scanning direction are printed on the leading edge area, the central area, and the trailing edge area of the sheet, In the central area, two parallel lines with an interval of a2 are printed normally.

  However, in the front end region of the paper, the interval in the sub-scanning direction is a1, and two parallel lines whose interval is smaller than a2 are printed.

  On the contrary, in the rear end area of the sheet, the interval in the sub-scanning direction is a3, and two parallel lines wider than the interval a2 are printed.

  Note that in the leading edge area and the trailing edge area of the sheet, the rotation speed and the sheet feeding speed are different between the photosensitive drum and the sheet, and thus printing is performed while causing slippage.

  The sub-scanning direction is the paper transport direction, and hereinafter, the sub-scanning direction is the X direction. Further, the direction in which the rotation axis of the photosensitive drum extends in the direction orthogonal to the sub-scanning direction X will be described as the main scanning direction Y.

  As a technique for avoiding such a change in the print length in the sub-scanning direction due to the difference between the rotational speed of the photosensitive drum and the paper feed speed, a technique disclosed in Patent Document 1 is known.

  In the technique disclosed in Patent Document 1, the exposure period of the photosensitive drum is made variable between the front end area and the rear end area with respect to the paper center area, so that the front end area and the rear end area are changed. The printing length in the sub-scanning direction with the partial area is corrected.

  By the way, in recent years, large-format LED printers have divided LED heads in which the LED head is divided into a plurality of (3 to 5) LED heads in the main scanning direction in order to reduce the cost of the LED head for exposing the photosensitive drum, The mainstream is a plurality (3 to 5) of small LED heads arranged in the main scanning direction.

  Such an LED head is hereinafter referred to as a “divided LED head”. An LED head that is not divided into a plurality of divisional LED heads in the main scanning direction will be referred to as a single-type LED head.

  In the split LED head, small LED heads are arranged side by side in the main scanning direction, so that the LED heads overlap each other and are shifted by several mm to several cm in the sub scanning direction.

The reference print position in the sub-scanning direction of each LED head is different. Therefore, by providing a correction circuit connected to the print control circuit of each LED head, printing equivalent to that of a single LED head can be obtained. .
JP 2001-92326 A

  In the LED printer device disclosed in Patent Document 1, when a single-type LED head is used, the exposure period of the photosensitive drum can be varied in order to correct the print length of the leading edge area and the trailing edge area of the paper. It has the composition to do.

  However, in the LED printer device disclosed in Patent Document 1, when a split type LED head is used instead of the single type LED head, each LED head of the split type LED head that is shifted in the sub-scanning direction is used. As a result, there is a problem in that normal printing cannot be performed.

  That is, there is a problem that printing in the main scanning direction is not connected, the printing length of the front end area and the rear end area cannot be corrected normally, and the printing accuracy is inferior (see FIG. 9B).

  The present invention has been made in view of such circumstances, and an object of the present invention is to correctly correct the print length of the leading end region and the trailing end region of the paper in an LED printer using a split LED head. It is to provide an LED printer.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. The invention according to claim 1 is a photosensitive drum that rotates in the sub-scanning direction about a rotation axis, and a print target at a first constant speed. A registration roller for supplying a medium to the photosensitive drum, a fixing unit for discharging the printing medium from the photosensitive drum at a second constant speed different from the first constant speed, and a first portion An LED head and a second partial LED head, wherein the first partial LED head and the second partial LED head overlap each other in parallel with the main scanning direction, and the sub-scanning direction The position of the divided type LED heads arranged at the LED head interval which is a predetermined interval and the printing medium supplied by the registration roller or the fixing device is detected, and the detected position and the LE are detected. In accordance with the head space, it has a, a printing control circuit for adjusting printing timings of the first portion LED head and the second portion LED head, the first relative to the rotation of the photosensitive drum The partial LED head is disposed in front of the second partial LED head, and the print control circuit is configured to position the print medium to which the print medium is supplied by the registration roller and the fixing device. The line clock pulse signal is output with a reference period corresponding to the LED head interval, and the detected position is supplied by the registration roller and the fixing device at the detected position. If it is the position of the medium to be printed, the print timings of the first partial LED head and the second partial LED head are output at the reference cycle. When the timing of the clock pulse signal is used and the detected position is the position of the medium to be printed which is supplied by the registration roller only, the reference period is delayed, The printing timing of the partial LED head is set to a timing delayed by a predetermined time from the line clock pulse signal output at the delayed reference period, and the detected position is supplied only by the fixing device. In the case of the position of the print medium being printed, the cycle of the reference period is made faster, and the print timing at the second partial LED head is made a timing delayed by a predetermined time from the advanced reference cycle. Or the detected position indicates that the printing medium is supplied by the registration roller and the fixing device. In the case of the character medium position, the print timing of the first partial LED head and the second partial LED head is the timing of the line clock pulse signal output in the reference period, and the detected position is When the medium to be printed is the position of the medium to be printed that is supplied only by the registration rollers, the period of the reference period is delayed and the printing timing of the second partial LED head is delayed. The timing is a predetermined time earlier than the line clock pulse signal output in the reference period, and the detected position is the position of the print medium supplied by the fixing device only. Is a predetermined time earlier than the reference period in which the period of the reference period is made earlier and the print timing of the first partial LED head is made earlier. A timing obtained by a LED printer, characterized in that.

The invention according to claim 2, wherein the printing control circuit changes the cycle of the reference cycle stages, an LED printer according to claim 1, characterized in that.

The invention according to claim 3, wherein the printing control circuit, according to claim 1 or claim 2, characterized in that to change the line clock pulse signal a predetermined time to cause or be earlier delayed from stepwise It is an LED printer.

According to a fourth aspect of the present invention, the LED printer includes a registration sensor that outputs a printing medium supply start signal when the LED printer detects that the printing medium is supplied to the registration roller, and the printing control is performed. 2. The circuit according to claim 1, wherein when the print medium supply start signal is input, the circuit detects the position of the print medium assuming that the position of the print medium is the position of the registration roller. The LED printer according to any one of claims 1 to 3 .

The invention according to claim 5 is a line clock set frequency storage unit in which the print control circuit stores a line clock set frequency that is a frequency of a line clock pulse signal that is a reference timing for printing by the divided LED head. A line clock generation circuit that generates the line clock pulse signal at the line clock set frequency, a line clock pulse signal counter circuit that counts the line clock pulse signal as a line clock pulse signal count value, and the printing medium. A first line clock pulse signal counter value corresponding to a boundary position between a tip end region conveyed only by the registration roller and a central region where the print medium is conveyed by the registration roller and the fixing device is A stored first boundary value storage unit; A second boundary value storage in which a second line clock pulse signal counter value corresponding to the boundary position between the central region and the rear end region where the print medium is conveyed only by the fixing device is stored. The line clock pulse signal count value and the first line clock pulse signal counter value, and outputs an L1 detection signal when the comparison result matches, and the line clock pulse signal An L2 comparison circuit that compares the count value with the second line clock pulse signal counter value and outputs an L2 detection signal when the comparison result matches, and an input of the L1 detection signal or the L2 detection signal The line clock setting frequency stored in the line clock setting frequency storage unit is stored in the front end region, the central region, or the rear end region. The first delay time until the first partial LED head prints from the line clock pulse signal is calculated in response to the input of the line clock setting frequency correction circuit and the L1 detection signal. And a second delay time calculator that calculates a second delay time from the line clock pulse signal until the second partial LED head prints according to the input of the L2 detection signal. A first LED head control circuit that prints with the first partial LED head after being delayed by the calculated first delay time from the input of the line clock pulse signal generated by the line clock generation circuit; Printing is performed by the second partial LED head after being delayed by the calculated second delay time from the line clock generated by the line clock generation circuit. That an LED printer according to any one of claims 1 to 4, and a second LED head control circuit, and having a.

According to a sixth aspect of the present invention, there is provided a photosensitive drum that rotates in the sub-scanning direction about a rotation axis, a registration roller that supplies a printing medium to the photosensitive drum at a first constant speed, and the first drum A fixing device that discharges the print medium from the photosensitive drum at a second constant speed different from the constant speed, a first partial LED head, and a second partial LED head, The first partial LED head and the second partial LED head are arranged at an LED head interval that is a predetermined interval in the sub-scanning direction with their end portions overlapping each other in parallel to the main scanning direction, and the photoconductor A split-type LED head in which the first partial LED head is disposed in front of the second partial LED head with respect to rotation of the drum ; the first partial LED head; and the second partial LED head; of A print control method for an LED printer having a print control circuit for adjusting character timing, and detecting a position of the print medium supplied by the registration roller or the fixing device, and detecting the detected position and the LED A print timing adjustment step of adjusting the print timing of the first partial LED head and the second partial LED head according to the head interval , wherein the print timing adjustment step is performed when the print medium is the print medium. It has a line clock pulse signal output at a reference period corresponding to the LED head interval at the position of the printing medium supplied by the registration roller and the fixing device, and the detected position is When the print medium is a position of the print medium supplied by the registration roller and the fixing device The step of setting the print timing of the first partial LED head and the second partial LED head as the timing of the line clock pulse signal output at the reference period, and the detected position are determined when the print medium is the print medium. When the position of the medium to be printed is supplied only by the registration roller, the line is output at the reference period in which the reference period is delayed and the print timing of the first partial LED head is delayed. A step of delaying a predetermined time from a clock pulse signal and the detected position is the position of the print medium supplied by the fixing device only, the reference The timing of the cycle is shortened, and the print timing of the second partial LED head is delayed by a predetermined time from the accelerated reference cycle. Or when the detected position is a position of the print medium supplied by the registration roller and the fixing device. The step of setting the printing timing of the partial LED head and the second partial LED head to the timing of the line clock pulse signal output at the reference period, and the detected position are determined by the registration roller only by the registration roller. If it is the position of the supplied medium to be printed, the cycle of the reference cycle is delayed and the print timing of the second partial LED head is output from the line clock pulse signal output at the delayed reference cycle. The step of making the timing advanced by a predetermined time and the detected position are such that the print medium is supplied only by the fixing device. If it is the position of the medium to be printed, the step of setting the cycle of the reference period earlier and setting the print timing at the first partial LED head to be a predetermined time earlier than the earlier reference cycle. A printing control method characterized by comprising:

According to a seventh aspect of the present invention, the print control circuit adjusts the print timing of the first partial LED head and the second partial LED head based on the conveyance speed of the non-print medium. The control is performed to match the position of the print image of the first partial LED head on the photosensitive drum with the position of the print image of the second partial LED head in the sub-scanning direction. The LED printer according to any one of claims 1 to 5 .

According to an eighth aspect of the present invention, there is provided a first memory that outputs print data to the first LED head in accordance with an instruction from the print control circuit, and print data to the second LED head according to an instruction from the print control circuit. A second memory that outputs to the first memory, and a data delay circuit that outputs print data obtained by delaying the number of scanning lines based on the LED head interval to the first memory and controls a delay in units of width between the scanning lines. The print control circuit further includes a timing for outputting the print data from the first memory to the first LED head and an exposure timing for the first LED head according to the detected position. A timing for outputting the print data from the second memory to the second LED head in accordance with the detected position, and the second LED A control for changing the exposure timing of the head, an LED printer according to claim 1, characterized in that to control the delay of the fine width than between the scanning lines by performing.

  According to this invention, the circuit that can delay the printing timing for each LED head of the divided LED head is provided, and the printing position of each LED head is changed in accordance with the change of the exposure period of the divided LED head. As a result, even in an LED printer using a split-type LED head, it is possible to correct the printing length of the leading edge area and the trailing edge area of the paper, and to perform printing with high accuracy. Play.

<Principle>
First, when printing the front end region of the paper, the print control circuit sets the exposure timing of the LED head arranged forward in the sub-scanning direction of the divided LED head to the LED head arranged backward. The printing length correction is performed so that the exposure cycle of the front end area of the paper is longer than that of the central area, that is, the printing in the sub-scanning direction is longer.

  Since the print control circuit corrects the print length in this way, the print position of the LED head arranged at the front can be printed close to the print position of the LED head arranged at the rear, so that the leading edge of the paper Even in the case of printing a partial area, it is possible to alleviate the printing deviation.

  Conversely, when the print control circuit prints the rear end region of the paper, the LED head disposed at the front of the exposure timing of the LED head disposed rearward in the sub-scanning direction of the divided LED head. The print length correction is performed so that the exposure period of the rear end area of the paper is shorter than that of the central area, that is, the printing in the sub-scanning direction is shortened.

  In this way, the print control circuit corrects the print length, so that the print position of the LED head arranged at the back can be printed close to the print position of the LED head arranged at the front. Even when the end region is printed, it is possible to alleviate the printing deviation.

  Further, the print control circuit has a circuit that can delay the print timing for each LED head of the split LED head, and the print position of each LED head can be changed in accordance with the change of the exposure cycle of the split LED head. Like that.

  In addition, the print control circuit includes a FIFO circuit for temporarily holding the print data of the divided LED heads and a counter circuit capable of changing the exposure timing stepwise.

  Further, in the split type LED head (in the case of three splits), the LED heads arranged in the front in the split type LED head with respect to the rotation direction of the photosensitive drum are referred to as LED head A and LED head C, and the rear The LED head arranged in the above will be referred to as LED head B.

  That is, LED head A and LED head C are at the same position with respect to the rotation direction of the photosensitive drum. The LED head A, LED head B, and LED head C are arranged in a staggered manner.

  Next, the operation of the print control circuit will be described with reference to FIGS.

  FIG. 4A shows a front end region, a central region, and a rear end region in the paper printed by the print control circuit.

  4B shows the exposure cycle of the print control circuit for each area in FIG. 4A, and the exposure timings of LED head A, LED head B, and LED head C of the print control circuit are shown in FIG. This is shown in FIG. FIG. 4D shows a print medium supply start signal, an L1 detection signal, and an L2 detection signal, which are detection signals, which will be described later.

  FIG. 5 is an operation diagram showing the operation of the print control circuit when printing from the front end region to the central region.

  FIG. 6 is an operation diagram showing the operation of the print control circuit when printing from the center area to the rear end area.

  First, when printing the front end area of the paper, the print control circuit has an exposure cycle longer than that of the central area (see A1 in FIGS. 4 and 5), and is provided in the LED head A and the LED head C. In the print control circuit, the reading of data from the FIFO circuit that temporarily holds the print data is delayed (see C1 in FIG. 5), and the exposure timing of the LED head A and the LED head C is set by the operation of the counter circuit. (See B1 in FIGS. 4 and 5).

  By doing so, even during printing of the front end region of the paper, printing without deviation between the LED heads can be performed without depending on the paper transport speed.

  Further, when printing the rear end area of the paper, the print control circuit makes the exposure cycle shorter than the central area (see A2 in FIGS. 4 and 5), and the print control circuit provided in the LED head B is used. The data reading from the FIFO circuit that temporarily holds the print data is delayed (see C2 in FIG. 6), and the exposure timing of the LED head B is changed to the exposure timing of the LED head A and the LED head C by the operation of the counter circuit. (See B2 in FIGS. 4 and 6).

  In this way, even during printing of the rear end region of the paper, printing without deviation between the LED heads is possible without depending on the paper transport speed.

  The central area of the paper is printed with a reference exposure cycle, and the print control circuits provided in the LED head A, LED head C, and LED head B use the LED head A and LED head C at the reference timing. Then, the LED head B is exposed (see FIGS. 4, 5 and 6).

  By doing so, even during printing in the central area of the paper, printing without deviation between the LED heads can be performed without depending on the paper conveyance speed.

  Note that the exposure timing of the LED head A and the LED head C from the leading end area to the central area of the paper is switched over several times for each main scanning line, and the exposure timing is set. By switching gradually, a switching deviation does not occur (see L1 and L2 in FIG. 4, L1 in FIG. 5, and L2 in FIG. 6).

As described above, by adjusting the exposure period and the exposure timing of the LED head according to the front end area, the central area, and the rear end area of the paper, printing is performed in all areas of the paper. Printing without any deviation between the LED heads is possible without depending on the sheet conveyance speed.
<First Embodiment>
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram showing the configuration of an LED printer according to an embodiment of the present invention.

  The LED printer includes a photosensitive drum 2, a registration roller 5, a fixing device 6, a registration sensor 8, a divided LED head 3, a print control circuit 1, and a developing device 7.

  The photosensitive drum 2 rotates at a constant rotation speed in the sub-scanning direction X around the rotation axis. The registration roller 5 supplies the printing medium 20 to the photosensitive drum 2 at a first constant speed. The fixing device 6 discharges the print medium 20 from the photosensitive drum 2 at a second constant speed.

  The first constant speed and the second constant speed are different in speed, and the second constant speed is faster than the first constant speed.

  The print medium 20 is a medium on which printing is performed by an LED printer, such as paper or film.

  When the registration sensor 8 detects that the printing medium 20 is supplied to the registration roller 5, the registration sensor 8 outputs a printing medium supply start signal.

  The developing device 7 supplies toner onto the electrostatic latent image on the photosensitive drum 2 formed by the split LED head 3.

  The split-type LED head 3 includes a first partial LED head and a second partial LED head, and the first partial LED head and the second partial LED head end to each other in parallel to the main scanning direction Y. The LED heads are arranged at predetermined intervals in the sub-scanning direction X, with the portions overlapping.

  An example of the split LED head 3 will be described with reference to FIG. In the figure, portions corresponding to those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

  2 has a small LED head A31, LED head B32, and LED head C33. The LED heads A31 to A32 are arranged in parallel with each other in the main scanning direction Y, and each LED head is arranged with a part of the end overlapping in the sub-scanning direction X, and the LED head A31 and the LED head C33. Are the same position in the sub-scanning direction X, and the LED head B32 is shifted from the LED head A31 and the LED head C33 so as not to overlap in the sub-scanning direction X.

  Thus, the split-type LED head 3 has a configuration in which small LED heads (LED head A31, LED head B32, and LED head C33) are arranged shifted in the main scanning direction Y and the sub-scanning direction X. . In the small LED head, each LED head is shifted by several mm to several cm in the sub-scanning direction X, and therefore the reference print position in the sub-scanning direction X is different.

  The reference print position is an irradiation position at which each LED head emits LED light for printing by the LED head, and is, for example, a center position in the sub-scanning direction X of the LED head.

  The first partial LED head and the second partial LED head described above are the first partial LED head of FIG. 2 are the LED head A31 and the LED head C33, and the second partial LED head is the LED head. B32.

  Alternatively, the first partial LED head and the second partial LED head are the first partial LED head of FIG. 2 is the LED head B32, and the second partial LED head is the LED head A31 and the LED head C33. is there.

  The split type LED head 3 prints on the printing medium 20 by exposing print data input from the outside onto the surface of the photosensitive drum 2 under the control of the print control circuit 1.

  The print control circuit 1 exposes print data input from the outside according to the LED head interval of the split LED head 3 and the print medium supply start signal detected by the registration sensor 8. Printing is performed by irradiating the photosensitive drum 2 with LED light from the split LED head 3 by adjusting the printing timing of printing by the first partial LED head and the second partial LED head while changing the cycle. .

  Next, the configuration of the print control circuit 1 will be described with reference to FIG. In the figure, portions corresponding to those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

  The print control circuit 1 includes a front end LINECLK storage unit 101, a central LINECLK storage unit 102, a rear end LINECLK storage unit 103, an L1 comparison circuit 104, an L2 comparison circuit 105, an AC delay register circuit 106, a B delay register circuit 107, AC delay value shift counter circuit 116, B delay value shift counter circuit 117, AC delay counter circuit 110, B delay counter circuit 111, LINECLK value shift counter circuit 114, LINECLK generation circuit 109, LED head B delay circuit 112, LED head control The circuit 130 and the LED head FIFO circuit 120 are included.

  The LED head B delay circuit 112 (print data delay unit) delays one of the print data simultaneously printed by the first partial LED head and the second partial LED head according to the LED head interval.

  For example, the LED head B delay circuit 112 delays only the print data printed by the LED head B32 by 90 lines in the print data input from the outside.

  The LED head FIFO circuit 120 (print data delay unit) uses the LED head B delay circuit 112 to print one of the print data simultaneously printed by the first partial LED head and the second partial LED head according to the LED head interval. This is a circuit that temporarily stores print data with a delay.

  The LED head FIFO circuit 120 is configured as, for example, a FIFO (First In First Out) circuit.

  The LED head FIFO circuit 120 includes an LED head AFIFO circuit 121, an LED head B FIFO circuit 122, and an LED head CFIFO circuit 123.

  The LED head AFIFO circuit 121 is a FIFO circuit that stores the print data of the LED head A31. The LED head B FIFO circuit 122 is a FIFO circuit that stores the print data of the LED head B32. The LED head CFIFO circuit 123 is LED head C33 is a FIFO circuit for storing print data.

  The LED head AFIFO circuit 121, the LED head BFIFO circuit 122, and the LED head CFIFO circuit 123 are circuits having the same configuration.

  As shown in FIG. 3, when only the LED head B delay circuit 112 is provided and the print data printed by the LED head B32 is delayed by the LED head B delay circuit 112, the LED head AFIFO circuit 121 and the LED head CFIFO circuit are provided. The print data without delay is stored in 123, and the print data delayed according to the LED head interval is stored in the LED head BFIFO circuit 122.

  For example, when the LED head B delay circuit 112 delays the print data input from the outside by only the print data printed by the LED head B32 by 90 lines as in the above example, the LED head AFIFO circuit 121. And the LED head CFIFO circuit 123, if the print data of the line number M (M is a natural number) is stored as the print data without delay, the LED head BFIFO circuit 122 stores the delayed print data. The print data of the line number (M + 90) is stored.

  As described above, the LED head FIFO circuit 120 stores the print data delayed according to the LED head interval for each of the LED heads A31, B32, and C33, and the stored print data is simultaneously printed. Even in the case where there is an LED head interval, the LED printer can perform connection correction. In this embodiment, not only the stored print data is printed at the same time, but also the print timings of the LED heads A31, B32, and C33 are set according to the displacement amount of the split-type LED head 3, as will be described later. By adjusting, even when the photosensitive drum is decentered, it is possible to perform printing without printing misalignment.

  Although only the LED head B delay circuit 112 corresponding to the LED head B32 has been described here, there may be a gap in the sub operation direction between the LED head A31 and the LED head C33. In such a case, similar to the LED head B delay circuit 112, an LED head A delay circuit corresponding to the LED head A31 and an LED head C delay circuit corresponding to the LED head C33 may be provided. Further, an LED head delay circuit corresponding to each LED head may be provided in accordance with an interval from a predetermined reference position determined in advance.

  Returning to the description of FIG. 3, the LINECLK generation circuit 109 (line clock generation circuit) has a line clock set frequency storage unit therein.

  The line clock set frequency storage unit stores a line clock set frequency that is a frequency of a line clock pulse signal that is a reference timing for printing by the split type LED head 3.

  The LINECLK generation circuit 109 generates a line clock pulse signal at the line clock setting frequency stored in the line clock setting frequency storage unit.

  The LINECLK counter circuit (line clock pulse signal counter circuit) 108 counts and stores the line clock pulse signal generated by the LINECLK generation circuit 109 as a line clock pulse signal count value.

  The LINECLK counter circuit 108 is initialized by setting the line clock pulse signal count value to 0, for example, when a print medium supply start signal is input.

  The L1 comparison circuit 104 includes a first boundary value storage unit therein, and the first boundary value storage unit includes a leading end region in which the print medium 20 is conveyed only by the registration roller 5 and the first boundary value storage unit. The first line clock pulse signal counter value corresponding to the boundary position between the central area where the printing medium 20 is conveyed by the registration roller 5 and the fixing device 6 is stored.

  The L1 comparison circuit 104 compares the line clock pulse signal count value counted by the LINECLK counter circuit 108 with the first line clock pulse signal counter value, and if the comparison result matches, the L1 detection signal is converted into an AC delay value. Output to the shift counter circuit 116.

  Note that the first line clock pulse signal counter value is a value determined according to the distance between the registration roller 5 and the fixing device 6.

  The L2 comparison circuit 105 has a second boundary value storage unit therein, and the printing medium 20 is conveyed by the registration roller 5 and the fixing device 6 to the second boundary value storage unit. A second line clock pulse signal counter value corresponding to the boundary position between the central area and the rear end area where the print medium 20 is conveyed only by the fixing device 6 is stored.

  The L2 comparison circuit compares the line clock pulse signal count value counted by the LINECLK counter circuit 108 with the second line clock pulse signal counter value, and if the comparison result matches, the L2 detection signal is shifted by the B delay value. Output to the counter circuit 117.

  Note that the second line clock pulse signal counter value is a value determined by the size of the print medium 20, that is, the length of the print medium 20 in the sub-scanning direction.

  For example, the size of the print medium 20 or the length in the sub-scanning direction is input to an input unit for inputting the size of the print medium 20 (not shown), and the input is performed according to the input size or the length in the sub-scanning direction. The unit stores the second line clock pulse signal counter value in the second boundary value storage unit.

  The line clock setting frequency correction circuit configured by the front end LINECLK storage unit 101, the central LINECLK storage unit 102, the rear end LINECLK storage unit 103, and the LINECLK value shift counter circuit 114 is an L1 detection signal or an L2 detection signal. In accordance with the input, the line clock setting frequency stored in the line clock setting frequency storage unit is adjusted corresponding to the front end region, the central region, or the rear end region.

  The tip LINECLK storage unit 101 (tip region setting frequency storage unit) stores a tip region setting frequency (for example, 1910 Hz) that is a set frequency in the tip region.

  The central portion LINECLK storage unit 102 (central region setting frequency storage unit) stores a central region setting frequency (for example, 1915 Hz) that is a setting frequency in the central region.

  The rear end LINECLK storage unit 103 (rear end region setting frequency storage unit) stores a rear end region setting frequency (for example, 1925 Hz) that is a set frequency in the rear end region.

  The LINECLK value shift counter circuit 114 stores the leading edge region setting frequency read from the leading edge LINECLK storage unit 101 in the line clock setting frequency storage unit in response to the input of the print medium supply start signal.

  Further, the LINECLK value shift counter circuit 114 stores the center area setting frequency read from the center LINECLK storage section 102 in the line clock setting frequency storage section in response to the input of the L1 detection signal.

Further, the LINECLK value shift counter circuit 114 stores the rear end region setting frequency read from the rear end LINECLK storage unit 103 in the line clock setting frequency storage unit in response to the input of the L2 detection signal.
Further, the LINECLK value shift counter circuit 114 stores the set frequency, which is changed stepwise from the tip region setting frequency to the center region setting frequency, in accordance with the input of the L1 detection signal. Store in the department.

  For example, when the L1 detection signal is input, the LINECLK value shift counter circuit 114 has a frequency between the front end region setting frequency and the central region setting frequency every time the line clock pulse signal is input. By calculating a set frequency by stepwise adding a predetermined value to the region set frequency, the set frequency is changed stepwise from the tip region set frequency to the center region set frequency.

  The LINECLK value shift counter circuit 114 stores the set frequency, which is changed stepwise from the central region setting frequency to the rear end region setting frequency, in the line clock setting frequency storage unit in response to the input of the L2 detection signal. To do.

  For example, when the input of the L2 detection signal is input, the LINECLK value shift counter circuit 114 has a frequency between the center region setting frequency and the rear end region setting frequency every time the line clock pulse signal is input. The set frequency is changed stepwise from the central region set frequency to the rear end region set frequency by adding the predetermined value to the central region set frequency stepwise to calculate the set frequency.

  The AC delay register circuit 106 (front end delay time storage unit) stores the print delay time (for example, −1 line) in the front end region as the front end print delay time.

  The AC delay value shift counter circuit 116 (first delay time calculation unit) calculates a first delay time from the line clock pulse signal until the first partial LED head prints according to the input of the L1 detection signal. To do.

  The AC delay value shift counter circuit 116 uses the leading edge printing delay time read from the AC delay register circuit 106 as the first delay time in response to the input of the print medium supply start signal, and responds to the input of the L1 detection signal. Thus, the value of the first delay time is set to 0.

  Further, the AC delay value shift counter circuit 116 calculates the first delay time stepwise from the leading edge printing delay time to the delay time value 0 according to the L1 detection signal.

  For example, when the L1 detection signal is input to the AC delay value shift counter circuit 116, every time the line clock pulse signal is input, the front end portion is changed from the front end print delay time until the delay time value becomes zero. By subtracting a predetermined value from the print delay time step by step, the first delay time is calculated step by step from the leading end print delay time value to 0 value.

  The B delay register circuit 107 (rear end delay time storage unit) stores the print delay time (for example, -2 lines) in the rear end region as the rear end print delay time.

  The B delay value shift counter circuit 117 (second delay time calculation unit) calculates a second delay time until the second partial LED head prints from the line clock pulse signal according to the input of the L2 detection signal. To do.

  The B delay value shift counter circuit 117 sets the value of the second delay time to 0 in response to the input of the print medium supply start signal, and reads from the B delay register circuit 107 in response to the input of the L2 detection signal. The trailing edge printing delay time is set as a second delay time.

  The B delay value shift counter circuit 117 calculates the second delay time stepwise from the value 0 to the trailing edge printing delay time in response to the input of the L2 detection signal.

  For example, when the L2 detection signal is input to the B delay value shift counter circuit 117, every time a line clock pulse signal is input, the B delay value shift counter circuit 117 gradually increases a predetermined value from a value 0 to the trailing edge printing delay time. By adding, the second delay time is calculated stepwise from the value 0 to the trailing edge printing delay time.

  The first LED head control circuit composed of the AC delay counter circuit 110 and the LED head control circuit 130 is a first LED head value calculated by the AC delay value shift counter circuit 116 from the input of the line clock pulse signal generated by the LINECLK generation circuit 109. The first partial LED head prints with a delay of one delay time.

  Specifically, the AC delay counter circuit 110 delays from the input of the line clock pulse signal generated by the LINECLK generation circuit 109 by the first delay time calculated by the AC delay value shift counter circuit 116, and controls the control signal AC Is output to the LED head control circuit 130. Thereafter, the LED head control circuit 130 to which the control signal AC is input prints with the first partial LED head.

  The second LED head control circuit composed of the B delay counter circuit 111 and the LED head control circuit 130 has a second delay time calculated by the B delay value shift counter circuit 117 from the line clock generated by the LINECLK generation circuit 109. Printing with the second partial LED head with a delay of

  Specifically, the B delay counter circuit 111 delays from the input of the line clock pulse signal generated by the LINECLK generation circuit 109 by the second delay time calculated by the B delay value shift counter circuit 117, so that the control signal B Is output to the LED head control circuit 130. Thereafter, the LED head control circuit 130 to which the control signal B is inputted prints with the second partial LED head.

  When the control signal AC from the AC delay counter circuit 110 or the control signal B from the B delay counter circuit 111 is input, the LED head control circuit 130, in accordance with the input control signal AC or control signal B, After the LED head FIFO circuit 120 outputs an LED head load signal for transmitting print data to the split-type LED head 3 and the transmission of the print data from the LED head FIFO circuit 120 to the split-type LED head 3 is completed, the split is performed. The LED head exposure signal for exposing the type LED head 3 is output to the divided type LED head 3.

  The LED head control circuit 130 includes an LED head A control circuit 131, an LED head B control circuit 132, and an LED head C control circuit 133.

  The LED head A control circuit 131 is a control circuit for controlling the LED head A31, the LED head B control circuit 132 is a control circuit for controlling the LED head B32, and the LED head C control circuit 133 is And a control circuit for controlling the LED head C33.

  The LED head A control circuit 131, the LED head B control circuit 132, and the LED head C control circuit 133 are control circuits having the same configuration.

  However, the control signal AC from the AC delay counter circuit 110 is input to the LED head A control circuit 131 and the LED head C control circuit 133, and the control from the B delay counter circuit 111 is input to the LED head B control circuit 132. The difference is that the signal B is input.

  Next, the control operations of the LED head control circuit 130, the LED head FIFO circuit 120, and the distributed division type LED head 3 will be described in detail.

  The LED head control circuit 130, the LED head FIFO circuit 120, and the split LED head 3 have the same configuration with respect to the LED head A31, the LED head B32, and the LED head C33, respectively.

  Accordingly, only the LED head A control circuit 131 of the LED head control circuit 130 for the LED head A31 and the LED head AFIFO circuit 121 of the LED head FIFO circuit 120 for the LED head A31 will be described here. .

  In response to the input of the control signal AC from the AC delay counter circuit 110, the LED head A control circuit 131 outputs an LED head A load signal having a certain time length to the LED head AFIFO circuit 121 and the LED head A31. After the LED head A load signal is output, the LED head A exposure signal is output to the LED head A31.

  The fixed time length of the LED head A load signal output from the LED head A control circuit 131 is a time length determined by the time length for transferring print data from the LED head AFIFO circuit 121 to the LED head A31. .

  The LED head AFIFO circuit 121 transmits the stored print data to the LED head A31 in response to the input of the LED head A load signal from the LED head A control circuit 131. Delete from the head AFIFO circuit 121.

  On the other hand, in response to the LED head A load signal being input from the LED head A control circuit 131, the LED head A31 sends the print data transmitted from the LED head AFIFO circuit 121 to the storage unit inside the LED head A31. Remember.

  Next, in response to the LED head A exposure signal being input from the LED head A control circuit 131, the LED head A31 exposes the print data stored in the storage unit inside the LED head A31 to the photosensitive drum 2. .

  The above LED printer as a whole executes printing by the operation described in <Principle>.

  With the above-described configuration, the print data is delayed by the LED head delay circuit B112, so that the exposure timing between the LED heads can be corrected in units of the distance between the lines in the sub-scanning direction, and the shorter distance can be adjusted. Also, fine correction can be performed by changing the exposure timing of each LED head by the LED head control circuit 130. This exposure timing can determine the resolution of the exposure timing in accordance with the frequency of the LINECLK generation circuit 109. According to an example of this embodiment, the LINECLK is changed in steps of 2.5 Hz in steps of a central frequency of 1915 Hz, a leading edge of 1910 Hz, and a trailing edge of 1925 Hz, and fine deviation can be corrected. . The exposure timing data corresponding to the paper conveyance speed and position is stored in a memory as a table, and the exposure timing is changed according to the detected paper conveyance speed and position, so that the LED heads can be more accurately connected. .

  Further, in the case of correction only by the LED head control circuit 130, it is possible to correct even a small deviation, so that a register, a counter, and the like become very large when performing a large correction in line width units. By performing rough correction in units of line width in advance by the LED head delay circuit B112, the registers, counters, and the like can be reduced, and the circuit scale can be reduced.

As described above, the LED printer according to the present embodiment has a circuit capable of delaying the print timing for each LED head of the divided LED head, and each LED head has a circuit in accordance with the change in the exposure cycle of the divided LED head. By changing the printing position, as shown in FIG. 7, even in an LED printer using a split-type LED head, it is possible to correct the printing length of the leading edge area and the trailing edge area of the paper. I can do it.
<Second Embodiment>
The second embodiment will be described with reference to FIG.

  In the first embodiment, a register, a comparison circuit, and a shift counter circuit are used. Instead, in the second embodiment, a CPU (Central Processing Unit) 201, a RAM (Random Access Memory) are used. ) 202 and ROM (Read Only Memory) 203 are used.

  The CPU 201 has functions of a LINECLK value shift counter circuit 114, an AC delay value shift counter circuit 116, a B delay value shift counter circuit 117, an L1 comparison circuit 104, and an L2 comparison circuit 105.

  The RAM 202 or the ROM 203 has functions of a front end LINECLK storage unit 101, a central LINECLK storage unit 102, and a rear end LINECLK storage unit 103.

  The LINECLK register circuit 204 in FIG. 8 is a line clock setting frequency storage unit included in the LINECLK generation circuit 109. Therefore, the LINECLK generation circuit 109 in FIG. 8 does not have a line clock set frequency storage unit therein.

As described above, the LED printer according to the present invention can be configured using the CPU 201, the RAM 202, and the ROM 203 without using the register, the comparison circuit, and the shift counter circuit. Note that the LINECLK value shift counter circuit 114, AC The delay value shift counter circuit 116, the B delay value shift counter circuit 117, or the CPU 201 each has a predetermined value each time a line clock pulse signal is input from a certain first value to a certain second value. The result of subtraction or addition was output. Instead, the output value is stored in the storage unit in advance, and is read out from the storage unit and output every time the line clock pulse signal is input. Also good.

  For example, at a frequency from the front end region setting frequency (for example, 1910 Hz) stored in the front end portion LINECLK storage unit 101 to the central region setting frequency (for example, 1915 Hz) stored in the central portion LINECLK storage unit 102. Then, the set frequency value obtained by stepwise adding the predetermined frequency value to the tip region setting frequency is sequentially stored in the tip center setting frequency storage unit.

  Next, for example, a LINECLK value generation circuit corresponding to the function of the LINECLK value shift counter circuit 114 is provided, and this LINECLK value generation circuit receives the print media supply start signal from the front end center setting frequency storage unit. The first stored set frequency value is read, and the read set frequency is output.

  Next, in response to the input of the L1 detection signal, the LINECLK value generation circuit reads the set frequency value stored second from the tip center setting frequency storage unit and outputs the read set frequency.

  Thereafter, each time the line clock pulse signal is input, the LINECLK value generation circuit sequentially reads the set frequency value stored from the tip center setting frequency storage unit and outputs the read set frequency.

  Note that the set frequency value for each size of the print medium 20 or the length in the sub-scanning direction is stored in the front-end center set frequency storage unit, and the print target set and input from the outside is stored. The value of the set frequency value may be selected according to the size of the medium 20 or the length in the sub-scanning direction.

  Here, an example in which the storage unit is used for only the LINECLK value shift counter circuit 114 has been described, but the same applies to the AC delay value shift counter circuit 116, the B delay value shift counter circuit 117, or the CPU 201. .

  In the embodiment, when printing the front end area of the paper, the print control circuit makes the exposure cycle longer than the central area, and sets the exposure timing of the LED head A and the LED head C to the LED head B. However, conversely, the exposure timing of the LED head A and the LED head C may be advanced with respect to the LED head B.

  Even in this way, even during printing of the rear end region of the paper, printing without deviation between the LED heads is possible without depending on the paper transport speed.

  In the embodiment, when printing the rear end area of the paper, the print control circuit makes the exposure cycle shorter than the central area, and sets the exposure timing of the LED head B to the LED head A and the LED head C. However, conversely, the exposure timing of the LED head B may be advanced with respect to the exposure timing of the LED head A and the LED head C.

  Even in this way, even during printing of the rear end region of the paper, printing without deviation between the LED heads is possible without depending on the paper transport speed.

  Note that the print control circuit 1 in FIG. 1 may be realized by dedicated hardware, or may be realized by a memory and a microprocessor.

  Further, a program for realizing each function of the print control circuit 1 shown in FIG. 3 is recorded on a computer-readable recording medium, and a program for realizing the function of the processing unit in the print control circuit 1 is recorded on the computer. The processing executed by the print control circuit 1 may be performed by recording the program on a readable recording medium, causing the computer system to read and execute the program recorded on the recording medium. Here, the “computer system” may include an OS and hardware such as peripheral devices. Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used. The “computer-readable recording medium” means a flexible disk, a magneto-optical disk, a ROM, a writable nonvolatile memory such as a flash memory, a portable medium such as a CD-ROM, a hard disk built in a computer system, etc. This is a storage device.

  In the present invention, the LED printer has been described. However, the present invention is not limited to this, and the present invention can be applied to a printer using a drum having a plurality of print heads.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design and the like within a scope not departing from the gist of the present invention.

  The present invention is suitable for use in a printer, particularly a printer using a drum having a plurality of print heads.

It is a block diagram which shows the structure of the LED printer by one Embodiment of this invention. It is a block diagram which shows the structure of the division | segmentation print head of FIG. FIG. 2 is a configuration diagram illustrating a configuration of a print control circuit of FIG. 1 according to the first embodiment. It is explanatory drawing explaining the principle of this invention. FIG. 5 is a sequence diagram illustrating an operation of a print control circuit from a front end region to a central region. FIG. 6 is a sequence diagram illustrating an operation of a print control circuit from a central area to a rear end area. It is a printing result figure by the LED printer of this invention. It is a block diagram which shows the structure of the printing control circuit of FIG. 1 by 2nd Embodiment. It is a printing result figure by the conventional LED printer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Print control circuit 2 Photosensitive drum 3 Split type LED head 5 Registration roller 6 Fixing device 7 Developing device 8 Registration sensor 20 Medium to be printed 31 LED head A
32 LED head B
33 LED head C
DESCRIPTION OF SYMBOLS 101 Lead part LINECLK memory | storage part 102 Center part LINECLK memory | storage part 103 Rear end part LINECLK memory | storage part 104 L1 comparison circuit 105 L2 comparison circuit 106 AC delay register circuit 107 B delay register circuit 108 LINECLK counter circuit 109 LINECLK generation circuit 110 AC delay counter circuit 111 B delay counter circuit 112 LED head B delay circuit 114 LINECLK value shift counter circuit 116 AC delay value shift counter circuit 117 B delay value shift counter circuit 120 LED head FIFO circuit 121 LED head AFIFO circuit 122 LED head B FIFO circuit 123 LED head CFIFO Circuit 130 LED head control circuit 131 LED head A control circuit 132 LED head B control circuit 1 3 LED head C control circuit

Claims (8)

A photosensitive drum that rotates in the sub-scanning direction about the rotation axis;
A registration roller for supplying a printing medium to the photosensitive drum at a first constant speed;
A fixing device for discharging the printing medium from the photosensitive drum at a second constant speed different from the first constant speed;
A first partial LED head and a second partial LED head, wherein the first partial LED head and the second partial LED head overlap each other in parallel to the main scanning direction, A split type LED head arranged at an LED head interval which is a predetermined interval in the sub-scanning direction;
The position of the printing medium supplied by the registration roller or the fixing device is detected, and the first partial LED head and the second partial LED are detected according to the detected position and the LED head interval. A print control circuit for adjusting the print timing with the head;
I have a,
The first partial LED head is disposed in front of the second partial LED head with respect to the rotation of the photosensitive drum;
The print control circuit is
The print medium has a line clock pulse signal that is output at a reference period corresponding to the LED head interval at the position of the print medium supplied by the registration roller and the fixing device.
When the detected position is the position of the print medium supplied by the registration roller and the fixing device, the first partial LED head and the second partial LED When the print timing with the head is the timing of the line clock pulse signal output in the reference cycle, and the detected position is the position of the print medium supplied with the print medium only by the registration roller The reference position is delayed, the print timing of the first partial LED head is delayed by a predetermined time from the line clock pulse signal output in the delayed reference period, and the detected position However, when the print medium is the position of the print medium supplied only by the fixing device, the reference period And early period, and the second portion timings delayed a predetermined time from the reference period which is faster the print timing of the LED head, or,
When the detected position is the position of the print medium supplied by the registration roller and the fixing device, the first partial LED head and the second partial LED When the print timing with the head is the timing of the line clock pulse signal output in the reference cycle, and the detected position is the position of the print medium supplied with the print medium only by the registration roller The timing of the reference period is delayed and the print timing of the second partial LED head is set to a timing that is a predetermined time earlier than the line clock pulse signal output in the delayed reference period. However, when the print medium is the position of the print medium supplied only by the fixing device, the reference period And early period, and the first portion and the print timing of the LED head is quickly given time than the standard period after the earlier the timing,
LED printer characterized by the above.   The print control circuit is
  Changing the period of the reference period in stages;
  The LED printer according to claim 1.   The print control circuit is
  A step of changing a predetermined time to be delayed or earlier than the line clock pulse signal;
  The LED printer according to claim 1 or 2, characterized in that   The LED printer is
  A registration sensor that outputs a print medium supply start signal when it is detected that the print medium is supplied to the registration roller;
  The print control circuit is
  When the print medium supply start signal is input,
  Detecting the position of the print medium as the position of the print medium is the position of the registration roller;
  The LED printer according to any one of claims 1 to 3, wherein the LED printer is provided.   The print control circuit is
  A line clock setting frequency storage unit that stores a line clock setting frequency that is a frequency of a line clock pulse signal that is a reference timing printed by the divided LED head;
  A line clock generation circuit for generating the line clock pulse signal at the line clock setting frequency;
  A line clock pulse signal counter circuit that counts the line clock pulse signal as a line clock pulse signal count value;
  A first line clock corresponding to a boundary position between a tip end region where the print medium is conveyed only by the registration roller and a central region where the print medium is conveyed by the registration roller and the fixing device. A first boundary value storage unit in which a pulse signal counter value is stored;
  A second boundary value storage in which a second line clock pulse signal counter value corresponding to a boundary position between the central area and a rear end area where the print medium is conveyed only by the fixing device is stored. And
  An L1 comparison circuit that compares the line clock pulse signal count value with the first line clock pulse signal counter value and outputs an L1 detection signal when the comparison results match;
  An L2 comparison circuit that compares the line clock pulse signal count value with the second line clock pulse signal counter value, and outputs an L2 detection signal when the comparison results match;
  In response to the input of the L1 detection signal or the L2 detection signal, the line clock setting frequency stored in the line clock setting frequency storage unit is adjusted corresponding to the front end region, the central region, or the rear end region. A line clock setting frequency correction circuit;
  A first delay time calculation unit that calculates a first delay time from the line clock pulse signal until the first partial LED head prints according to the input of the L1 detection signal;
  A second delay time calculating unit that calculates a second delay time from the line clock pulse signal until the second partial LED head prints in response to an input of the L2 detection signal;
  A first LED head control circuit that prints with the first partial LED head delayed from the input of the line clock pulse signal generated by the line clock generation circuit by the calculated first delay time;
  A second LED head control circuit for printing with the second partial LED head, delayed from the line clock generated by the line clock generation circuit by the calculated second delay time;
  The LED printer according to any one of claims 1 to 4, wherein the LED printer is provided. A photosensitive drum that rotates in the sub-scanning direction about the rotation axis;
A registration roller for supplying a printing medium to the photosensitive drum at a first constant speed;
A fixing device for discharging the printing medium from the photosensitive drum at a second constant speed different from the first constant speed;
A first partial LED head and a second partial LED head, wherein the first partial LED head and the second partial LED head overlap each other in parallel to the main scanning direction, A divided type in which LED heads are arranged at predetermined intervals in the sub-scanning direction, and the first partial LED head is arranged in front of the second partial LED head with respect to rotation of the photosensitive drum. An LED head;
A print control circuit for adjusting print timing of the first partial LED head and the second partial LED head;
A printing control method in an LED printer having:
The position of the printing medium supplied by the registration roller or the fixing device is detected, and the first partial LED head and the second partial LED are detected according to the detected position and the LED head interval. It has a print timing adjustment process that adjusts the print timing with the head ,
The printing timing adjustment step
The print medium has a line clock pulse signal that is output at a reference period corresponding to the LED head interval at the position of the print medium supplied by the registration roller and the fixing device.
When the detected position is the position of the print medium supplied by the registration roller and the fixing device, the first partial LED head and the second partial LED The step of setting the print timing with the head to the timing of the line clock pulse signal output at the reference period, and the detected position is the position of the print medium where the print medium is supplied only by the registration rollers. If it is, the step of delaying the cycle of the reference cycle and setting the print timing of the first partial LED head to a timing delayed by a predetermined time from the line clock pulse signal output at the delayed reference cycle And when the detected position is the position of the print medium supplied by the fixing device only. And early period of the reference cycle, comprising the step of said second portion timing print timing is delayed a predetermined time from the reference period which is early above the LED head, or,
When the detected position is the position of the print medium supplied by the registration roller and the fixing device, the first partial LED head and the second partial LED The step of setting the print timing with the head to the timing of the line clock pulse signal output at the reference period, and the detected position is the position of the print medium where the print medium is supplied only by the registration rollers. In this case, the step of delaying the cycle of the reference cycle and setting the print timing of the second partial LED head to a timing that is a predetermined time earlier than the line clock pulse signal output in the delayed reference cycle And when the detected position is the position of the print medium supplied by the fixing device only. Print control method wherein a cycle of the reference cycle and faster, comprising the step of said first portion and the print timing of the LED head is quickly given time than the standard period after the earlier the timing, characterized in that.   The print control circuit adjusts the print timing of the first partial LED head and the second partial LED head based on the conveyance speed of the non-print medium, whereby the first on the photosensitive drum. 6. The control according to claim 1, wherein the position of the print image of the partial LED head is matched with the position of the print image of the second partial LED head in the sub-scanning direction. LED printer according to item.   A first memory that outputs print data to the first LED head according to an instruction from the print control circuit; a second memory that outputs print data to the second LED head according to an instruction from the print control circuit; A data delay circuit that outputs print data obtained by delaying the number of scanning lines based on the LED head interval to the first memory and controls a delay in units of the width between the scanning lines;
  And a control for changing a timing of outputting the print data from the first memory to the first LED head and an exposure timing of the first LED head according to the detected position. The control for changing the timing of outputting the print data from the second memory to the second LED head and the exposure timing of the second LED head according to the detected position is performed. 2. The LED printer according to claim 1, wherein a delay having a width smaller than a width between scanning lines is controlled.

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