JPH0722320B2 - Laser printer - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a laser printer that performs multicolor or multitype printing.

[Technical Background of the Invention and Problems Thereof] In this type of laser printer, an electrostatic latent image forming unit that forms an electrostatic latent image on a photoconductor by operating a laser beam, and the electrostatic latent image is developed. A plurality of developing means and a plurality of developing means are arranged around the photoconductor to perform multicolor or multitype printing.

By the way, conventionally, there has been a problem that the scanning length of each laser beam emitted from a plurality of electrostatic latent image forming means on the photosensitive member is different. That is, as shown in FIG. 15B, for example, the scanning start points of the two laser beams a and b are S ₁ and S ₂ ,
If the scanning end points are E ₁ and E ₂ , this scanning start point is S ₁ ,
S ₂ , scan end points E ₁ and E ₂ , respectively, scan lengths l ₁ and l ₂
Was different. This occurs when there is a difference in the optical path lengths of the laser beams a and b until the photoconductor is exposed, and it is extremely difficult to optically solve this adverse effect.

[Object of the Invention] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a laser printer capable of easily correcting a difference in scanning length of a plurality of laser beams. ..

[Outline of the Invention] An outline of the present invention for achieving the above object is to provide a charging unit for charging a photoconductor, and a laser beam to scan the photoconductor charged by the charging unit with a laser beam. In a laser printer for performing various kinds of printing by arranging a plurality of sets of image forming means for forming an electrostatic latent image, and image forming means and developing means around the photoconductor, the laser printer corresponds to the plurality of image forming means. A plurality of video clocks are provided to generate a video clock from the scanning start point to the scanning end point of each laser beam, and the time width of the video clock generated by the video clock generating means is changed. And a scanning length correcting means for correcting the scanning length of the laser beam.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. The present embodiment relates to a two-color laser printer equipped with an automatic document feeder.

FIG. 1 shows the appearance of the apparatus of this embodiment, which is an automatic document feeder (auto document feeder, abbreviated as ADF hereinafter) 1 and a scanner unit 11 which will be described later.
0, a printer main body 100 including a laser print unit (hereinafter abbreviated as an LBP unit) 300, and a control unit 400.

The ADF 1 is composed of a document cover 2 having a document transport unit 30 described later, a document supply 3, and a document tray 4. The document cover 2 is rotatable in the direction of the arrow in the figure by operating the grip portion 2A, and when the automatic document feeding function is not used, the document can be placed directly on the exposure glass. . A liquid crystal display (hereinafter abbreviated as LCD) that displays an image read by a scanner unit 110 described later is provided on the upper surface of the original cover 2.
5 and a first operation panel 6 for inputting information for image editing are arranged.

The printer body 100 is provided with a second operation panel 101 for inputting print information on the upper surface side, and an upper cassette 321 and a lower cassette 322 for paper feeding are detachably arranged on one side surface, A paper discharge tray 344 is provided on the other side surface.

In this embodiment, the ADF 1, the printer body 100 and the control unit 400 are integrally configured, and each member is an independent single unit, and a method of connecting them with a cable, an image bus, etc. is not adopted. The space for arranging the members is minimized, the side panel and the like can be commonly used, and the weight and cost of the device can be reduced.

Here, regarding the main control block of the apparatus of this embodiment,
A brief description will be given with reference to the drawings. In FIG. 2, CPU401
Controls the laser printer.
An LCD interface 407, a serial interface 408, a scanner interface 409, and an LBP interface 410 are connected to the bus line as interfaces of the various units. Also, the LCD
The interface 407, the scanner interface 409, and the LBP interface 410 are connected to the first color image data bus line and the second color image data bus line, respectively. The first color page memory 403 and the first color page memory address controller 4 are used as image processing of the first color image data output via the scanner interface 409.
04 is provided, and further, as image processing of the second color image data, a second color page memory 405 and a second color page memory address controller 406 are provided. When the image editing information is input from the first operation panel 6, the first and second color page memory address controllers 404 and 406 cause the first and second color page memories 403 and 405 to operate.
Various image edits are performed by controlling reading and writing of the image data.

Next, the details of each of the above units will be described.

First, the details of the ADF1 are shown in FIGS. 3, 4 (A) and (B).
Will be described with reference to.

In FIG. 3, the document feeding section 3 of the ADF 1 is composed of a document placing table 10 and a separate feeding section 15.

As shown in FIG. 4 (A), the document placing table 10 has document guides 11 and 11 which are movable according to the width of various documents (for example, A5, B5, B4 sizes, etc.). The manuscript guides 11 and 11 include racks 12 and 12 inside the manuscript table 10. A pinion 13 is rotatably mounted on the center line L in the width direction of the document placed on the document table 10. The pinion 13 meshes with the racks 12, 12. Therefore, when one of the document guides 11 is moved according to the document width, the action of the racks 12 and 12 and the pinion 13 common thereto causes the other document guide 11 to move.
Also moves the same distance, and both document guides 11 are moved to the center line L.
It always moves symmetrically with respect to. Further, a bent portion 12A is formed by being bent downward on one side surface side of one of the racks 12, and the moving path of the bent portion 12A is various as shown in FIGS. 4 (A) and (B). A document width detection switch 14 having a plurality of switches 14A, 14B ... Arranged at a position corresponding to the document width is provided. The width of the document placed on the document table 10 can be detected from the combination of the ON and OFF states of the plurality of switches 14A, 14B ,.

The separating / feeding unit 15 sequentially separates and feeds the originals stacked in a batch on the original placing table 10 one by one. Inside the separating / feeding section 15, there is provided a document presence / absence detection switch 16 which comes into contact with the upper surface of the stacked documents and is displaced depending on the number of documents. Further, there are provided a stopper 17 that comes into contact with the lower surface of the original document and presses the original document upwardly, and a feeding roller 18 that is disposed so as to face the stopper 17 and frictionally delivers the uppermost original document. The separating / feeding roller 19 including a pair of rollers separates a plurality of documents fed between the pair of rollers and feeds them one by one. The original supplied from the separating / feeding roller 19 is a registration roller.
The supply timing is controlled by 20 to be transmitted. An original detection switch 21 is provided at the subsequent stage of the registration roller 20, and the original detection switch 21 counts the originals that are passing and detects the length of the original being passed. Therefore, the document width detection switch 14 and the document detection switch 21 can automatically detect the vertical and horizontal sizes of the document.

The original document transport unit 30 built in the original document cover 2 is composed of an endless belt that moves on the exposure glass 111, rollers that drive the endless belt, and the like, and exposes the original document that is separated and fed by the separating and feeding unit 15. The sheet is conveyed along the glass 111 to a predetermined document stop position. The separating and feeding unit 15 and the document conveying unit 30 convey one document on the exposure glass 111, and after the exposure is completed, the document is synchronized with the processing timing in the printer body 100. The sheet is discharged and conveyed to the tray 4, and the next original is conveyed and driven.

The LCD 5 and the first operation panel 6 are provided on the upper surface of the original cover 2. Scanner unit 11
By providing the LCD 5 which is an example of a display device for displaying the image read at 0, it is possible to visually check whether the image to be copied is accurately read after the image is read and before the copying of the image is started. Can be recognized by
It is possible to prevent useless copying operation. Therefore, it is possible to confirm whether or not the image is tilted or whether or not the document reading area, which will be described later, is correctly designated before copying, and visually confirm the image after copying as in the conventional case. It is possible to significantly reduce wasteful consumption of paper as compared with that of paper. It should be noted that such a display device is not limited to the LCD 5 and various display methods can be adopted. Further, if it is arranged on the upper surface of the document cover 2 as in this embodiment, the operator can easily see the screen of the LCD 5 and can easily confirm the read image. In this way, when it is placed on the upper surface of the document cover 2, a flat type display is preferable, and in addition to the LCD 5, the LED display is used.
A method such as display or plasma display may be adopted.

Next, the scanner unit 110 in the printer body 100 will be described with reference to FIGS. 3, 5, and 6. The scanner unit 110 performs exposure scanning on the original on the exposure glass 111 and inputs the original reflected light to the photoelectric conversion unit 120. That is, as shown in FIG. 3, the exposure light source 112 and the first mirror 113 are attached to the first carriage 116, and the second mirror 114 and the third mirror 115 are attached to the second carriage 117. The guide shaft 118 can be reciprocated in the direction of the arrow. Then, the reflected light of the document, which is emitted from the light source 112 and scanned over the entire exposure area of the document, is reflected by the lens 11
The light is condensed at 9 and enters a CCD (charge coupled device) 121 of the photoelectric conversion unit 120 and is converted into image data.

Here, the control block of the scanner unit 110 will be described with reference to FIG. The scanner CPU 130 controls the scanner unit 110, and the program memory 131 connected to its bus line stores the execution procedure of the scanner unit 110. The carriage drive control unit 132 drives and controls the stepping motor or the like to drive the first and second carriages 116 and 117, and the speed thereof is variable according to the enlargement / reduction mode signal from the scanner unit CPU 130. ing. This first, second
By changing the moving speed of the carriages 116 and 117 of
The density of the document in the feeding direction (sub-scanning direction) is made variable so that the image can be enlarged or reduced. Light source control unit 133
Is for driving the exposure light source 112 to emit light during the reading of the original. The ADF control section 134 controls the ADF 1 and controls the document size based on the outputs of the document width detection switch 14 and the document detection switch 21.
It is transmitted to the U130 and used for selection of the document reading area. Also, the document presence detection switch
Based on the output of 16, when the document is no longer left, the scanner operation is finished. The binarization processing control unit 135 outputs a timing signal required for data reading to the photoelectric conversion unit 120, and binarizes the 6-bit digital data output from the photoelectric conversion unit 120. To do. The binarized image data is sent to the scanner interface 409 via the main controller interface 136,
It will be transmitted to the first and second color image data buses.
The photoelectric conversion unit 120 includes the CCD 121, an amplifier 122 that amplifies this output, and an A / D that performs analog-digital conversion.
It is composed of a converter 123. Then, the light source 112
The light emitted from the first to third mirrors 113, 114 and 115 is incident on the CCD 121 through the lens 119 and the CCD 12
The charge accumulated in 1 is amplified by the amplifier 122, and the A / D converter 1
It is designed to be digitally converted at 23. A / D
The output of the converter 123 is, for example, 6 bits / dot. Further, in the photoelectric conversion unit 120, while the density in the sub-scanning direction is variable according to the enlargement / reduction mode,
The speed of the clock corresponding to each dot is constant, and the density in the main scanning direction (corresponding to the width direction of the document) is also constant (for example, 16 lines / mm). The enlargement and reduction of the image in the main scanning direction will be described later. FIG. 6 shows main timing signals during the document reading operation of the scanner unit 110. In the figure, “HSYNO” is a synchronization signal for each line in the sub-scanning direction, “DAT” indicates data, and for example, binarized data is output in 8-bit units during reading by eight data buses. To be done. "STBO" is the above "DA
The strobe signal is “T”, and “VSYNO” indicates that the sub-scanning direction is in the document reading area.

Next, the LBP unit 300 will be described. In FIG. 3, reference numeral 301 denotes a photoconductor for recording information with a laser beam.
The first developing device 303, the second charging device 304, the second developing device 305, the discharging lamp 306 for increasing the peeling efficiency, and the transfer charger 30.
7, a peeling charger 308, a cleaning device 309, etc. are arranged.

Further, 310 denotes two laser beams a and b on the photoconductor 301.
Is a laser scanner unit as an image forming means for scanning, modulating and recording. Then, the laser beam a emitted from the laser scanner unit 310 is
Is reflected by the first reflection mirror 311 and is exposed on the photoconductor 301 by the first exposure unit 350 between the first charging device 302 and the first developing device 303 from directly above the photoconductor 301. It is designed to be illuminated. On the other hand, the laser beam b is reflected by the second and third reflection mirrors 312 and 323, respectively, and the second charger 3
The photosensitive member 301 is irradiated with the second exposing portion 351 between the 04 and the second developing device 305.

As shown in FIG. 7, the laser scanner unit 310 includes first and second laser diodes 314 and 315, and first and second laser diodes 314 and 315.
The collimator lenses 316 and 317 that make the laser beams a and b emitted from the second laser diodes 314 and 315 parallel beams, and a prism that bends at a right angle so that the optical path of the laser beam a becomes parallel to the laser beam b.
318, a polygon mirror 319 that scans the laser beams a and b, respectively, and an f.theta. Lens 320 arranged at the subsequent stage of the polygon mirror 319 as shown in FIG.

Then, when a laser driving circuit (not shown) is operated, ON / OFF of the light emission of the laser beams a and b from the first and second laser diodes 314 and 315 and the light amount thereof are controlled, and these laser beams a and b are collimated. One surface of the polygon mirror 319 is irradiated with the light through the lenses 316 and 317 and the prism 318, and is scanned in the main scanning direction. Thereafter, the laser beams a and b are reflected by the first reflection mirror 311 or the second and third reflection mirrors 312 and 313 via the f · θ lens 320,
The surface of the photoconductor 301 is exposed to form an electrostatic latent image. To the electrostatic latent image, developers of different colors are supplied by the first and second developing units 303 and 305 to visualize the electrostatic latent image (this operation will be described later in detail).
Alternatively, this image is transferred onto a sheet fed from the lower cassette 322.

Here, the arrangement of the exposure unit with respect to the photoconductor 301 will be described. Since the apparatus of this embodiment is a two-color laser printer, the first and second exposure units 350 and 351 are provided at two locations. The angle θ (see FIG. 3) between the beam incident direction on the photoconductor 301 to the first exposure section 350 and the beam incident direction on the photoconductor 301 to the second exposure section 351 is an acute angle. The first and second exposure units 350 and 351 are arranged so that The reason for arranging in this way is as follows. That is, since various portions must be arranged around the photoconductor 301 as described above, the first and second exposure units 350 and 35 are provided.
If 1 is placed away from each other (when each beam intersection θ is an obtuse angle), the space for placing other members will be narrowed. For this reason, it is necessary to increase the drum diameter of the photoconductor 301 to secure a space, and the device becomes large.
Therefore, in order to effectively use the space around the photoconductor 301, the arrangement as in this embodiment is preferable. Furthermore, by arranging in this way, the first and second developing units 303 and 305 can be configured to have substantially the same shape, and the cost can be reduced by sharing the parts. Further, in order to perform the development of the second color, it is necessary to recharge by the second charger 304 after the development by the first developing device 303, but this recharging is performed as soon as possible after the development of the first color. Is preferred.
Therefore, it is also advantageous in that the recharging can be quickly performed by the arrangement of the exposure unit according to the present embodiment. Furthermore, the laser beam a,
If b is arranged so that the same optical path lengths are arranged close to each other, the design for making the optical path lengths the same becomes easy. When printing the data of the second color in the vicinity where the data of the first color is exposed and developed, the exposed portion of the data of the first color on the photoconductor 301 is rotated to the second exposed portion. The time difference Δt during this period is Δt = θ / ω depending on the angle θ and the angular velocity ω [deg / sec] of the photoconductor.
It becomes [sec]. Therefore, it is advantageous to reduce θ in order to reduce the time difference Δt.

Next, it is desirable to provide the first and second exposure parts 350 and 351 in the upper half peripheral region A of the photoconductor 301 as shown in FIG. The reason for this is that the transfer charger 307, which is arranged at a position facing the exposed portion, can be installed below the photoconductor 301. By doing so, the sheet to which the image is transferred can be transported by utilizing its own weight, and the configuration of the transport mechanism can be simplified. If the exposure unit is arranged on the lower half of the photoconductor 301, the transfer charger and the like will be arranged on the upper half of the photoconductor 301, and then the paper must be held by a belt or the like and conveyed. However, such a configuration is very difficult in many cases, and the configuration becomes complicated, which is not preferable. Next, by disposing the exposure section on the upper half circumference of the photoconductor 301, the mirror surface of the first reflection mirror 311 can face downward as shown in FIG. 8 (B). Therefore, dust or the like does not adhere to the mirror surface due to its own weight. The adhesion of dust to the mirror surface has a great influence on the image quality, which is also advantageous in this respect. If the exposure part is arranged in the lower half of the photoconductor 301, the mirror surface of the reflection mirror 352 has to be directed upward as shown in FIG. 8B, and maintenance for removing dust and the like is complicated. Is not preferable.

Next, a paper feeding system and a paper discharging system will be described with reference to FIG.

The upper set 321 includes an upper paper feed roller 323 for taking out sheets one by one from the cassette, an upper paper no switch 324 for detecting that there is no more paper in the cassette, and a paper size of the upper cassette 321. And an upper cassette size detection switch 325 for detecting Similarly, the lower cassette 322 also includes the lower paper feed roller 32.
6. A lower paperless switch 327 and a lower cassette size detection switch 328 are provided. Further, above the upper cassette 321, there is provided a manual feed guide 330 capable of manually inserting a sheet, a manual feed switch 331 for detecting the sheet inserted by the manual feed guide 330, and a sheet whose insertion has been confirmed by this switch. A manual paper feed roller 332 for transporting the sheet is disposed.

A registration roller 340 is arranged at the destination of the conveyance path of the sheet fed from the upper cassette 321, the lower cassette 322 or the manual feed guide 330. This registration roller 340 is
The image developed on the photoconductor 301 is synchronized with the sheet, and the sheet is sent to the transfer charger 307. The paper on which the image is transferred by the transfer charger 307 is attached to the suction belt 341 via the peeling charger 308.
Is discharged to the front by the fixing device 342, and after fixing the image by the heat and pressure by the fixing device 342, the discharging roller 343
By this, it is carried out to the paper discharge tray 344.

Next, the two-color printing operation of the LBP unit 300 will be described.

In the process of the two-color laser printer, a two-color toner image is formed on the photoconductor 301 during one rotation of the photoconductor 301 and is transferred onto a sheet (plain paper). That is, as shown in FIG.
After the two-color toner image is formed on the photoconductor 301, the transfer charger 307 transfers the two-color toner images onto the sheet at once, and the fixing device 342 fixes the toner images to fix the two-color toner images. Printing is completed. On the other hand, the photoconductor 301
The untransferred toner above is collected by the cleaning device 309,
After cleaning the photoconductor 301, the next print cycle is started.

In this embodiment, the discharge contact developing method is adopted in order to obtain a two-color printed image by rotating the position of the photoconductor 301. In the contact developing method such as the conventional magnetic brush developing method, the first toner image first formed on the photoconductor 301 as shown in FIG. 9 (A) is shown in FIG. 9 (B). Is scraped off by the second developer as shown in FIG. 9 (C).
As shown in FIG. 3, the first and second toners may cross each other and adhere to the photoconductor 301. Further, as shown in FIG. 10, the first toner attached and conveyed on the photoconductor 301 may be mixed in the second developing device 305 to cause a significant deterioration in image quality.

As a non-contact developing method, there is also a method of using a magnetic one-component developer, but since it contains black magnetic powder, it is not suitable for multi-color printing because a highly saturated color toner cannot be obtained. is there.

Therefore, in this embodiment, a two-component developer in which an iron powder carrier and a non-magnetic toner are mixed by a magnetic brush is used. That is, as shown in FIG. 11, the two-component developer 355 is agitated by the mixer 356 and the magnetic brush roll 357 to be frictionally charged. The magnetism of the iron powder carrier causes the two-component developer 355 to be attracted to the magnetic brush roll 357 and rotationally conveyed. The two-component developer 355 on which the magnetic brush is formed is regulated to have an appropriate layer thickness by the doctor blade 358 and rubbed against the non-magnetic developing roll 359. Then, by applying a DC bias voltage 360 between the magnetic brush roll 357 and the developing roll 359, only the non-magnetic toner 355A in the two-component developer 355 is electrostatically separated to the developing roll 359. The developing roll 359 holds an appropriate gap (for example, 200 μm) with the photoconductor 301 by a gap adjusting ring (not shown). Further, since the non-magnetic toner 355A is positively charged by friction with the iron powder carrier, the developing roller 35
The non-magnetic toner 355A conveyed by 9 flies to the electrostatic latent image pattern of which the potential is attenuated on the photoconductor 301 and is developed. The two-component developer 355 that has been rubbed by the developing roll 359 is scraped off by a scraper 361 and used for another development. Further, the toner density of the two-component developer 355 is detected by a toner density sensor (not shown), and toner is replenished from a toner hopper (not shown) based on this detection so that the toner density is constantly controlled to be constant. There is.

Next, to prevent color mixture in multicolor printing, see FIG.
This will be described with reference to (D) and FIGS. 13 (A) to (D).
FIGS. 12A to 12D are schematic explanatory views showing the occurrence of color mixture. Uniformly charged on the photoconductor 301 (shown in FIG. 12 (A))
After that, when the first exposure is performed, the surface potential of the exposed portion is attenuated to Vs, the first toner adheres to the surface potential, and the first development is performed (see FIG. 12B). After that, when the second exposure is performed, this exposed portion is also attenuated to the surface potential Vs (shown in FIG. 12C). Then, when the second development is performed in this state, the second toner develops not only the second exposed portion but also the first exposed portion, and a mixed color is developed (shown in FIG. 12D). This development is the first
This occurs because the potential of the exposed portion is lower than the development start potential during the second development.

In order to solve this color mixing problem, it is necessary to restore the surface potential of the first exposed portion to the surface potential before exposure. At this time, it is necessary to keep the surface potential of the unexposed portion unchanged. In order to satisfy these conflicting factors, a corotron / corona discharge charger that superimposes AC and DC voltages is used as the second charger 304 in this embodiment.

A color mixing prevention process using this charger will be described with reference to FIGS. 13 (A) to 13 (D).

(1) The photoconductor 301 is uniformly positively charged by the first charger 302 (see FIG. 13A).

(2) The first exposure is performed by the laser beam a from the first laser diode 314, the first toner is attached to the exposed portion having the surface potential V _s1 , and the first development is performed (see FIG. 13 (B)). .

(3) Recharging is performed by the second charger 304, and the surface potential of the first exposed portion is raised to a potential V _{s2 that} is substantially equal to the surface potential of the unexposed portion (see FIG. 13 (C)).

(4) The second exposure is performed by the laser beam b from the second laser diode 315, the second toner is attached to the second exposed portion, and the second development is performed (see FIG. 13D). At this time, since the surface potential of the first exposed portion is higher than the development start voltage at the time of the second development, the color mixture as described above does not occur.

Next, details of laser scanning in the laser scanning unit 310 will be described. FIG. 14 is a schematic perspective view illustrating laser scanning from the laser scanner unit 310 to the photoconductor 301. It should be noted that each member shown in the figure is denoted by the same reference numeral in FIG. 3 or 7, and the detailed description thereof is omitted. There are two problems in this laser scanning that greatly affect the image quality. That is, the photoconductor 3 by the laser beam a from the first laser diode 314
Let S _{1 be} the scanning start point in the main scanning direction on 01 and E _{1 be the} scanning end point, and let the laser beam b from the second laser diode 314 be.
Let S _{2 be the} scanning start point and E _{2 be the} scanning end point according to
There is a problem shown in FIGS. Figure 15 (A) shows
It is shown that both scanning start points S ₁ and S ₂ do not lie on the same line and a difference d occurs. This is because the laser beams a and b from the first and second laser diodes 314 and 315 are the polygon mirror 319.
Occurs when it is not parallel before being incident on. On the other hand, the 15th
FIG. 6B shows that the scanning lengths of the laser beams a and b by the first and second laser beams 314 and 315 in the main scanning direction are different from l ₁ and l ₂ . This occurs when the laser beams a and b after passing through the f.theta. Lens 320 have different exposure lengths until the photosensitive member 301 is exposed.

The present embodiment is configured as follows in order to solve the above two problems.

Here, first, the input / output relationship between the LBP unit 300 and the LBP interface 410 will be described with reference to FIGS. 16 and 17. This LBP unit 300 and LBP interface 4
The signals between 10 and 10 are roughly classified into control signals and image-related signals.

As the control signal, LB from the LBP interface 410 is used.
There is a command signal such as a print command to the P unit 300, and there is a status signal indicating the state of the LBP unit from the LBP unit 300 to the LBP interface 410, such as a print ready signal.

As the image-related signals, from the LBP unit 300 to the LBP interface 410, there are a video clock signal in the main scanning direction and a horizontal synchronization signal in the sub-scanning direction as shown in FIG. It is emitted in correspondence with the print area, and is the first and second video clock signals and the first and second horizontal synchronizing signals in correspondence with the signals for two colors. The LBP interface 410 is
The first and second video data signals are output to the LBP unit 300 based on the first and second video clock signals and the first and second horizontal synchronizing signals.

The control system block of the LBP unit 300 is the
Print control for generating first and second video clock signals and first and second horizontal synchronizing signals and driving the first and second laser diodes 314 and 315 based on the first and second video data signals It has a section 370 (details of which will be described later). This print control unit 370 is the same as that of the microcomputer 371.
Connected to I / O port 372. The microcomputer 371 is connected to input / output devices such as various sensors and motors necessary for printing operation in addition to the print control unit 370.
An O port 372, a ROM 374 that stores an operation program of the LBP unit 300, a RAM 375 that stores data, a timer 376 that generates a clock, and a scanner CPU 373 that controls the respective units.

Next, an example of the print controller 370 will be described with reference to the block diagram shown in FIG. 18 and the timing chart shown in FIG. FIG. 18 shows that one photodetecting element 200 detects the scanning start points of the laser beams a and b, and the scanning start of the two laser beams a and b to the photoconductor 301, which is one of the problems described above. This is a circuit that corrects the displacement between the positions E ₁ and E ₂ .

In FIG. 18, the photo-detecting element 200 detects the horizontal synchronizing position of the laser beam a, and its output, the horizontal synchronizing detection signal S _1, is connected to the set terminal of the flip-flop 201. The Q output of the flip-flop 201 is input to the reset terminal R of the quaternary counter 202 as the line start signal S ₂ . Further, the oscillating output S ₃ of the oscillator (OSC) 203 (1/4 clock corresponding to 1/4 dot) is input to the clock terminal of the quaternary counter 202. Clock signal S which is the Q output of the quaternary counter 202
Reference numeral ₄ serves as a video clock, which is synchronized with the horizontal sync detection signal S _1, and the oscillation output S ₃
Is divided by 4 and output with an accuracy of 1 clock (corresponding to 1 dot).

On the other hand, the line start signal S ₂ that is the Q output of the flip-flop 201 is input to the reset terminal R of the counters 204, 205A and 206A, and the clock signal S ₄ that is the output of the quaternary counter 202 is the counters 205B and 206B. It is designed to be input to the clock terminal C _P. The counter 204 is a monostable timer, and the counters 205A and 206A are presettable programmable counters. Then, the output S _{5 of the} counter 204 is a sample which is periodically generated corresponding to the horizontal synchronization detection signal S ₁ for the purpose of detecting the horizontal synchronization position and for generating the sample pulse of the laser light quantity stabilizing circuit. It is a timer signal. Further, the counter 205A sets the horizontal left margin to the counter 20A.
6A is a counter for setting a horizontal write margin.

The output S _{6 of the} counter 205A is input to one input terminal of the AND gate 208A via the inverter 207A,
The output S _{7 of} 206A is input to the other terminal of the AND gate 208A. And this AND gate 20
Output S ₈ AND gates 209A to the output S ₄ and the two inputs and output the quaternary counter 202 8A is adapted to be output to the LBP interface 410 as the first video clock signal.

Further, an AND gate 210A is provided which receives the output of the AND gate 208A and the first video data signal as two inputs. The output of the AND gate 210A and the counter
The output of the OR gate 212A, which receives the output S ₅ of 204 through the inverter 211 and the signal as two inputs, is the first laser drive signal.
It is designed to serve as S ₉ . Then, the first laser drive signal S ₉ is adapted to issue and drive the first laser diode 314 via the first laser drive circuit 213A.

On the other hand, the drive control system for performing the second color printing includes the counters 205A and 206A, the inverter 207A, and the AND gate 208 shown in FIG.
A, 209A, 210A, OR gate 212A and first laser drive circuit 21
It has the same configuration with the suffix "A" of 3A as the suffix "B". The counters 205B and 206B are programmable, and the output S of the counter 205B is S.
The left margin in the horizontal direction is set by ₁₀ and the right margin in the horizontal direction is set by the output S _{11 of the} counter 206B. Further, the second video clock signal S ₁₂ and the second video drive signal S ₁₃ are based on the signals S ₅ , S ₁₀ , S ₁₁ of the counter 204, the counter 205B, and the counter 206B as in the case of the first color printing. It is supposed to be created.

The counters 205A and 206A, the inverter 207A, and the AND gates 208A and 20 for outputting the first video clock signal S ₈
9A is the first video clock generation circuit 420. Further, the counters 205B and 206B, the inverter 207B, and the AND gates 208B and 209B for outputting the second video clock signal S ₁₂ are used as a second video clock generation circuit 421.

Thus, in the present embodiment, the two types of laser beams a,
The horizontal sync detection of b can be achieved by one photodetector element 200. Conventionally, the horizontal synchronization detection of the two types of laser beams a and b is performed by two independent photodetecting elements, so that the number of parts is increased and the position adjustment of the two photodetecting elements is time-consuming and complicated. Met. Therefore, according to the present embodiment, it is possible to reduce the cost of the device by reducing the number of parts, and it is possible to improve the assemblability without requiring complicated adjustment work.

Further, as shown in FIG. 10 (A), when a deviation d occurs between the scanning start points S ₁ and S ₂ of the laser beams a and b, the _first and _second video clock generation means as the video clock generation means are generated. circuit
It is possible to easily correct this with 420 and 421. That is, the counter 205A for setting the horizontal left margin of the first color laser beam a or the second color laser beam b
The scanning start point E ₁ of the first-color laser beam a is delayed or the scanning start point E ₂ of the second-color laser beam b is changed by changing any preset value of the counter 205B that sets the left margin. This deviation d can be eliminated by accelerating it. Therefore, the deviation d can be easily corrected without requiring a complicated optical adjustment for making the laser beams a and b into an accurate parallel beam before entering the polygon mirror 319.

Next, the first and second horizontal synchronizing signals S relating to the sub-scanning direction.
_17, a configuration of outputting the S ₂₀ with reference to the timing charts shown in block diagram and Figure 20 shows in FIG. 18 will be briefly described. Counter 215A as a configuration for outputting a first horizontal synchronization signal S _17, 216A, inverter 217A, the AND gates 218A, 219A
Is provided. Similarly, the counter 215B as outputs the second horizontal synchronizing signal S _20, 216B, inverter 217B,
AND gates 218B and 219B are provided. Here, to describe the output of the first horizontal synchronizing signal S _17, the counter 215A, 216A is a presettable programmable counter, the counter 215A is a set of top margin, the counter 216A is to perform the setting of the bottom margin It has become. The page top signal S ₁₄ is input to the gate terminals G of the counters 215A and 216A, and the clock terminals C _P
The line start signal S _2, which is the output of the flip-flop 201, is input to. Then, the subsequent operation can generate the first horizontal synchronizing signal S ₁₇ in the same manner as the generation of the first video clock signal S ₈ . The same applies to the creation of the second horizontal synchronizing signal S ₁₀ .

Next, another configuration example of the print control circuit 370 capable of correcting the scan length mismatch shown in FIG.
This will be described with reference to FIGS. FIG. 21 is a block diagram showing another configuration example of the print control circuit 370, and the point that the block shown in FIG. 21 differs from the block shown in FIG.
This is the addition of the quaternary counter 220 and the selector 230.
And, while the first clock signal S ₄ from the quaternary counter 202 is generated with an accuracy of 1 clock, the newly added quaternary counter 220 is synchronously extended by 1/4 clock. Two clock signals S ₄ ′ are generated, and the number of video clocks is totally reduced by such clock signals so that a beam having a short scanning length is apparently extended. First the selector 100, the second clock signal S _4, 'enter a, the short scanning length beam the second clock signal S _4' S ₄ and outputs to select.

The scanning length correcting means 242 for correcting the scanning length of the beam in this way uses the first and second clock signals S ₄ , S ₄ ′ as reference clocks according to the scanning length of the beam in this embodiment. A reference clock generating circuit 234 for outputting the reference clock and the reference clock generating circuit 240,
It is configured by a selector 230 which selects and outputs to 241.

Here, details of the quaternary counters 202 and 222 and the selector 230 in the scanning length correcting means 242 will be described with reference to FIGS. 22 and 23. In FIG. 22, reference numeral 221 denotes a presettable N-ary counter, which counts the oscillation output S ₃ of the oscillator 203 after the horizontal detection signal S ₁ is output from the photodetector element 220. Counter 221
The preset value of DIP switch 22
It can be set arbitrarily by 2. The shift register 223, the NAND gate 224, the NOR gate 225 and the inverter 226 are gate circuits that give the N-ary counter 221 a predetermined operation. Clock terminal C _P of shift register 223
It said oscillation output S ₃ is in is adapted to input the line start signal S ₂ to the reset terminal R, the Q _0,
Two Q ₁ outputs are input to the NAND gate 224, and two Q ₂ outputs are input to the CI and CE terminals of the N-ary counter 221. The output of the NOR gate 224 and the output of the inverter 226 are input to the NAND gate 225, and the output of the NAND gate 225 is N.
It is adapted to be input to the LD terminal of the binary counter 221.
The inverter 226 is adapted to input a carry from the CO terminal of the N-ary counter 221. Here, as shown in FIG. 23, after the line start signal S ₂ is input to the reset terminal R of the register 223 and the N-ary counter 221, the oscillation output S ₃ is input to the clock terminal C _P of the register 223 and the N-ary counter 221. Then, output S _{21 of} NOR gate 225 and output Q _{2 of} register 221 S
₂₂ is input to the N-ary counter 221 as a signal shown in the figure, and the carry output S ₂₃ is applied to the Co terminal of the N-ary counter 221.
Will occur. And this carry output S ₂₃
Is input to the J, K terminals of one of the JK-F-F227, JK-type flip-flops (hereinafter abbreviated as JK-F-F) 227, 228 which are inverted through the inverter 226 to form a quaternary counter. Has become. The other JK / F-F228 J, K
The terminal is always high level. Where this JK
F-F227 and 228 are to toggle at the rising edge of the clock input when both J and K terminals are at high level, and retain the previous state when both J and K terminals are at low level.
Since the line start signal S ₂ is input to the reset terminal R of the JK · F-F227, 228, the JK · F is synchronized with the input of the line start signal S _2.
-F227,228 starts operation, will be divided by four to the oscillation output S ₃ is a clock input of the JK · F-F227. When both the J and K terminals of the JK / F-F227 are low level (when carry of the N-ary counter 221 occurs), one clock of the oscillation output S ₃ (corresponding to 1/4 dot) Only the toggle operation will be interrupted. As a result,
As shown in Fig. 23, the output of JK / F-F228 is "11/4" when a carry occurs when the pulse interval during normal operation is "1", and is stretched by 1/4 clock. become.

On the other hand, the counter 202 is composed of two JK · F−F202A and 202B, and since its J and K terminals are always at high level, its Q output is exactly 4 as shown in FIG.
It becomes a divided clock.

Selector 230 for inputting the outputs of both quaternary counters 202, 220
Has AND gates 231 and 234 for inputting the output of the quaternary counter 220 and AND gates 232 and 233 for inputting the output of the quaternary counter 202. Then, the other inputs of the AND gates 231 and 233 are configured so that a high level is input when the switch 235 is "open" and a low level is input when the switch 235 is "closed". On the other hand, the other input of the AND gates 232 and 234 is connected to the switch 235.
When the switch 235 is "open", a low level is input by the action of the inverter 236, and when the switch 235 is "closed", a high level is input. Further, an OR gate 237 for inputting two outputs of the AND gates 231 and 232
And an OR gate 238 for inputting two outputs of the AND gates 233 and 234. Therefore, the switch 235
Is open, the OR gate 237 outputs the second clock signal S ₄ ′ which is the output of the quaternary counter 220, and the OR gate 238 outputs the first clock signal S 4 which is the output of the quaternary counter 202. _Will output ₄ . When the switch 235 is closed, the OR gate 237 outputs the first clock signal S ₄ and the OR gate 238 outputs the second clock signal S ₄ ′. If the second clock signal S ₄ ′ is used as the video clock of the laser beam having a short scanning length by switching the switch 235, the scanning length on the photoconductor 301 can be increased.

For example, correction will be described when one of the laser beams having a regular scan length of 200 mm is shorter by 1 mm. 12 resolution
In the case of lines / mm, in order to correct the scanning length difference of 1 mm, the video clock signal of the beam with a short scanning length is 2400 pulses (200 × 1
You only have to stretch 12 pulses per 2). Where N
Since the oscillation output S ₃ that is the clock input of the binary counter 221 is a 1/4 video clock, the preset value of the N-ary counter 221 may be set to a value such that one carry is generated every 50 counts. In this way, FIG. 10 (B)
The difference in scanning length as shown in can be corrected. The preset value of the N-ary counter 221 can be corrected by appropriately setting the preset value according to the scanning length of the beam, the scanning length difference between the two beams, and the resolution.

Next, various image editing functions of this device will be described.

First, an example of the first and second operation panels 6 and 101 will be described with reference to FIG.

The first operation panel 6 for inputting image editing information
Has various keys as shown in FIG. A combination mode selection key 50 is a key for selecting a mode in which images of a plurality of originals sequentially supplied from the ADF 1 are combined on one sheet and output. When the ADF 1 is not used, a mode is selected in which the images of the originals sequentially placed on the exposure glass 111 are combined on one sheet and output. Further, a first ten-key pad 56 is provided as an original sheet number input means for inputting the number of original sheets to be combined with an image on one sheet. Incidentally, reference numeral 57 in the figure denotes a sheet number display for displaying the number of documents input by the first ten-key pad 56. The image extraction mode selection key 51 is a key that is selected when a part of the image of the original is extracted instead of the image of the entire document and is copied onto paper. As means for designating the extraction area of the original, for example, coordinates 5A provided around the LCD 5 are used to input the coordinates of the extraction area through the first ten-key pad 56. The extraction area can be specified for a plurality of originals when the above-mentioned combination mode is selected by the above means, and the extraction area can be divided and specified for one original. The output position designation mode selection key 52 is a key for selecting a mode for designating a position where a document image is formed on a sheet fed from the upper cassette 321 or the lower cassette 322. Then, as the sheet image forming apparatus designating means, the coordinates 5A and the first
It is also designed to be used as the numeric keypad 56. The image erasing mode selection key 53 is a key selected when partially erasing an image of a document. In particular, it is effective in erasing the contour lines of a plurality of originals when the synthesizing mode is selected. In addition, as the means for designating the image erasing area, the coordinate 5A is used.
And the first numeric keypad 56 is also used. The framed mode selection key 55 is a key selected when a new contour line is added after the contour line of the original is erased by the selection of the image erasing mode. The pagination mode selection key 55 is a key that is selected when pages are attached to paper. In this embodiment, there are two types of pagination modes, one of which is a mode in which pages are attached in the order of document input corresponding to images of a plurality of documents formed on one sheet in the combining mode. The other one is a mode in which pages are added in the output order of paper. When selecting the former mode, press the pagination mode selection key 55 and then press the "input order" selection key 55A.
Press. To select the latter mode, press the pagination mode selection key 55 and then press the "Output order" selection key 55B.
Press.

Next, the second operation panel for inputting print information and the like
101 will be described. In FIG. 24, reference numeral 150 is a start key for starting a copying operation, and 151 is a second numeric keypad which is an example of a sheet number input means for inputting the number of sheets for copying the same original image. This second numeric keypad
The number of sheets entered in 151 is displayed on the number display 152.
Further, a cancel key 153 for canceling the number of sheets is provided. 154 is a cassette selection key for selecting the upper cassette 321 and 155 is a cassette selection key for selecting the lower cassette. Reference numeral 156 is an LCD display for displaying various states of the printer, and is adapted to schematically display the printer standby state, paper size information, jam occurrence, toner replenishment, and the like.

Reference numeral 157 denotes an auto magnification mode selection key. When the key is pressed, the document image is automatically enlarged or reduced based on the sizes of the document image and the paper. Reference numeral 158 denotes a magnification designation key, which can be set to a desired enlargement magnification or reduction magnification by selecting a numerical value with the second numeric keypad 151 after pressing this key. A key 159 is used to select a reduction or enlargement mode according to a predetermined document size and paper size.

Next, a page memory address controller that performs various image editing operations based on the input information to the first operation panel 6 will be described. In this embodiment, the first color and second color page memory address controllers 404 and 406 are provided to form an image of two colors, but they have the same configuration. FIG. 25 is a block diagram showing an example of the first color image memory address controller 404.

The page memory address controller controls the address and read signal / write signal of the page memory.

First, address control of the page memory will be described.
The page memory address controller shown in this embodiment is
It is provided to use the page memory efficiently. The address of the page memory is usually determined by giving a read signal / write signal as a count in the main scanning direction and a horizontal synchronization signal (HSYNC) signal as a count in the sub scanning direction. By the way, when the page memory is addressed by such control, the number of good divisions of the page memory in the main and sub-scanning directions is 1024, 2048, 4096, 8192, ... However, the number in the main scanning direction actually used is rarely close to the above number, and in the case of this device, the main scanning width is about 5000 bits (about 625 bytes) and the sub-scanning width is about 7000 ( About 875
Byte). Therefore, in order to satisfy this address space, an address space of 8192 × 8192 bits (1024 bytes × 1024 bytes) is required, and waste of both the memory element and the counter element increases.

In order to minimize the above waste, the apparatus of the present embodiment has the XW (T
P) An address control block including a register 423, an adder / subtractor 424, a latch circuit 425, an address counter 426, and an address transceiver 427 is provided. Here, XW is a value corresponding to the width of the output paper (width in the main scanning direction), and the CPU 401 determines this XW based on the output of the upper and lower cassette size detection switches 325, 328, and the CPU bus, data XW via transceiver 420 and command port 421
(TP) Set in register 423. Further, when the read / write start address (TP) is set in the XW (TP) register 423 in the same manner, the number of TP + XW × N (N is an integer) is accessed when the address control block inputs the HSYNC signal. The start address in the main scanning direction is accessed. In addition, a read signal (PRDC) or a write signal (PWTC) from the image bus is transmitted via the clock receiver 440 to the line control / clock generator 437.
When the input signal is input to, a write / read clock synchronized with the read signal and the write signal is generated, and the address in the main scanning direction is sequentially updated by this clock. By addressing in this manner, the address becomes a continuous one-dimensional number with almost no space, and the number of memory elements and counter elements can be minimized. When the composite mode for forming a plurality of original images on one sheet is selected, the start address (TP) may be set at a predetermined position according to each original.

Next, a block that partially reads data from the page memory or partially controls data rewriting will be described. For this purpose, XN register 430, XN counter 431,
A YN register 432 and a YN counter 433 are provided. X
N and YN are values in the main scanning direction and the sub-scanning direction that respectively specify an area on the image memory, and these values are controlled by the CPU 401 to the XN registers 430 and YN via the command port 421.
It is set in register 432. The XN and YN values are XN and YN counters 431 and 4 for counting the read / write clocks.
When set to 33, the XN counter 431 outputs a carry after carrying out XN count of the read / write clock, and carries up in the sub-scanning direction. When carry is output from both the XN and YN counters 431 and 433, it means that the designation of the access range is completed. At this time, based on the output of the line control / clock generator 437, the status transceiver 439
The page end signal (PGEND) is output to the image bus to clear all data in the access range.

In this embodiment, not only the specific data in the page memory can be erased but also the specific data can be written. At this time, after setting TP, XN and YN which specify the data write position in the same manner as above, D shown in FIG.
MA (Direct Memory Access) Controller 41
By programming the data address and data length at which the data to be written is stored for 1 and enabling the DMA operation, this data is written on the page memory. The data to be written is stored in the program memory 402. In this case, the data may be a character, a symbol, a specific pattern, or the like, and more specifically, a page code or an outline of a document.

The mask register 434 and the mask counter 435 are used when invalidating image data in a certain range of the page memory. When an address according to a predetermined range is set in the mask register 434, the data in that range is forced. It is supposed to be zero.

Address register 436 contains the address currently being accessed by this page memory address controller.
This address is provided so that the CPU 401 can recognize it.This address is sent to the CPU via the data transceiver 420 and the CPU bus.
It will be forwarded to the 401.

The line control receiver 438 is a line synchronization signal (NXLIN).
The bus control receiver 441 controls the data high enable signal (DHENB) and the image disable signal (I
MDIS) respectively and transfer them to the line control / clock generator 437.

Next, the page memory as an image memory will be described. The first-color and second-color page memories 403 and 405 are constructed as shown in FIG. This page memory 403
Is capable of storing 1 or 2 Mbytes of data in accordance with the address signal output from the page memory controller 404. As the memory device, 64 256K-bit dynamic RAMs are used, and the memory space is 2M bytes. The bus that is normally used is an image bus, and image data controlled by each control signal of the page memory address controllers 404 and 406, the print control unit 370, etc. is transferred from this image bus to the data buffer 40.
It is designed to be read / written via 3A. Further, data is written from the CPU bus via the data buffer 403B only in the above-described DMA mode (a mode for writing a page code or the outline of a document or the like).

Next, the configuration of the scanner interface 409 will be described below.
This will be described with reference to FIGS. The scanner interface 409 transmits the control signal from the CPU 401 to the scanner unit 110, and at the same time, the scanner unit 110
The state of is read to the CPU 401 side, and the read image data is reduced and enlarged to be transmitted to the page memories 403 and 405. That is, as shown in FIG. 28, an address signal is input from the CPU bus to the address code conversion unit 450,
Data is input to the bus transceiver 458, and various data is written to either the basic command register 452 or the command register 453 according to the address, or the scanner unit 110 written to either the status bus receiver 454 or the basic status receiver 455. Status data of the CPU via the bus transceiver 458, CPU bus
It is supposed to read in 401. In this way, commands are sent to the scanner unit 110 and the state of the scanner unit 110 is read by the CPU 401. Further, in the interface signal between the scanner interface 409 and the scanner unit 110, the data (IDAT) input / output via the bus transceiver 457.
Has a bus structure, and the status signal (ISDAT) transmitted from the timing generator 451 to the scanner unit 110.
And 3 depending on the state of the two signals of the command signal (ICMD)
Have two states. That is, the status data of the scanner unit 110, the command data to the scanner unit 110, and the image data read by the scanner unit 110
Have two states. Further, the timing of transmission / reception of this various data is controlled by a busy signal (ISBSY) output from the scanner unit 110, a write signal (IWR) output from the timing generation unit 451 and the like. The interrupt F / F 459 outputs an interrupt signal (INTO) to the CPU 401.

The image data from the scanner unit 110 input through the bus transceiver 457 is output to the image processing unit 456, where image enlargement / reduction (processing in the main scanning direction) and trimming (image extraction) are performed. Will be sent to the image bus.

Details of the image processing unit 456 will be described with reference to FIG. The image processing unit 456 has two line memories 460 and 461, and an image is enlarged or reduced by alternately reading and writing the two line memories 460 and 461. Since it is necessary to read and write image data as serial data in the line memories 460 and 461, image data input in parallel is serially converted by a parallel-serial converter (hereinafter referred to as PS converter) 462. , The image data read from the line memories 460 and 461 are serial-parallel converted (hereinafter referred to as SP
It is designed to output to the converter image bus in parallel in 463).

Then, an address signal for reading and writing to the line memories 460 and 461, a write / read timing signal, and P
Various blocks for outputting a timing signal for setting the conversion timing of the -S converter 462 and the SP converter 463 are provided. The write timing generation circuit 464 and the read timing generation circuit 465 output two types of clocks, that is, eight clocks corresponding to 8-bit image data each time a strobe (STB) signal is input and a clock obtained by delaying the eight clocks. To do. Then, this clock is converted into the PS converter 46.
It is used as the timing signal of the 2, S-P converter 463 and also as the write / read timing signal via the timing selector 467, and is further used for generation of the address signal.

As a block for generating the address signal, a line memory address counter parameter register 468, a decimal fraction counter unit 469, a fractional address counter integer unit 470, an integer address counter 471, and two address selectors 472 and 473 are provided. The line memory address counter parameter register 468 sets the enlargement or reduction ratio to be counted for the decimal point counter section 469, and the decimal point address counter integer section 470 and the integer address counter 4
An initial value is set for 71. The fractional counter unit 469 adds the enlargement and the fractional multiplication factor for each clock and outputs the carry of the sum of the fractional parts. For example 0.7
In the case of double, the carry is output up to the third clock, but the carry is not output at the fourth clock.
(0.7 × 3 = 2.1, 0.7 × 4 = 2.8 and there is no carry in the decimal part). The fractional address counter integer unit 470 is adapted to advance counting only when a carry occurs in the fractional counter unit 469. On the other hand, integer address counter
In 471, the count is advanced every clock.

Then, when the data is reduced, the output of the fractional address counter integer unit 470 is used as an address for the line memory 472 or 47.
By writing the data to 3, the data is written out one by one every several data, and the read address is performed by the integer address counter 471 to generate reduced data.
On the other hand, when expanding the data, the integer address counter 471 writes the data to the line memory 471 or 473 as it is, and the read address is performed by the decimal address counter integer unit 470, so that the same data is continuously read one by one. It is designed to create enlarged data. For this purpose, there are provided address selectors 472 and 473 for inputting the outputs of the fractional address counter integer part 470 and the integer address counter 471, respectively, and selecting and outputting them to the line memories 460 and 461. The address selection by the address selectors 472 and 473 is performed based on the output of the enlargement / reduction timing controller 474.

Here, the data reduction and enlargement operations are shown in FIG.
This will be described with reference to the timing chart shown in FIG.
FIG. 30 (A) is a timing chart showing the data writing operation to the line memories 460 and 461, and FIG. 30 (B).
6 is a timing chart showing a data read operation from the line memories 460 and 461. The data D08 to D01 are serial data by the clock CP from the write timing generation unit 464. Further, the decimal point counter unit 469 outputs a carry from the rising edge of the clock CP, and has a reduction ratio such that no carry is output at the seventh clock, for example. Therefore, the fractional address counter integer unit 470 sequentially updates the write address only while the carry is being output from the fractional counter unit 469, but when the carry is not output, the write address is not updated and the data D02 , A common address ADS + 6 is designated for D01. Therefore, the same address data D02 and D01 are continuously written on the line memory, and as a result, the data D02 is erased and data is lost. Since this data is read by the address of the integer address counter 471 which is updated corresponding to the clock CP, as shown in FIG. Will be generated.

When expanding the data, clock as shown in Fig. 30 (A).
The line memory 460 or 461 is written with the address of the integer address counter 471 updated corresponding to the CP. Therefore, the data D08 to D01 are directly written in the line memory. Then, the reading of the data from this line memory is performed based on the address of the decimal address counter integer part 470. For example, as shown in FIG. 30 (B), if the decimal point counting unit 469 has an enlargement ratio at which the carry is not output at the sixth clock CP, the decimal point address counter integer unit 470 is set while the carry is not output. The same address (ADS + 5) is designated twice continuously without updating the address, and as a result, the same data is continuously read and the data is expanded.

In addition, the above enlargement and reduction operations enlarge the image in the main operation direction,
This is a case of reduction, and enlargement and reduction of the image in the sub-operation direction are performed by changing the scan speed of the carriages 116 and 117 as described above. Further, in the normal size mode, the uniform size mode signal is input to the decimal point counting unit 469, and the decimal point address counter integer unit 470 causes the integer address counter 4
As a result of outputting the same address as 71, enlargement and reduction are not executed.

Next, image extraction (trimming) in the image data processing unit 456 will be described. This trimming is performed by extracting the data in the image extraction area by defining the start position of the data and the end position of the data.
The data start position is set by connecting the most significant bit of each of the write and read addresses to the chip select terminal of the memory element, and writing and reading are possible after the bit becomes 1. To do.
The setting of the position of the end of the data is the address Next, the image extraction (trimming) in the image data processing unit 456 will be described. This trimming is performed by extracting the data in the image extraction area by defining the start position of the data and the end position of the data.
The data start position is set by connecting the most significant bit of each of the write and read addresses to the chip select terminal of the memory element, and writing and reading are possible after the bit becomes 1. To do.
Address comparator 47 is used to set the position of the end of data.
An address is set to 5, and a gate 4 provided at the subsequent stage of the P-S converter 462 by the address comparator 475.
76, or by controlling the data selector 478 provided in the preceding stage of the SP converter 463. The address comparator 475 operates by receiving the address of the integer address counter 471. Therefore, when the image reduction mode and the trimming are performed together, the integer address counter 47 is read at the time of reading the data.
Since 1 is used, the data selector 478 that selects this read data is controlled by the address comparator 475. On the other hand, when the image enlargement mode and triming are performed together, the integer address counter 471 is used when writing data,
The gate 476, which preselects the data to be written, will be controlled by the address comparator 475.

The above trimming operation is performed in the main scanning direction, and trimming in the sub scanning direction is performed as follows. That is, sub-scanning direction parameter register 480, address counter 48
1, an address comparator 482 and a gate 483 are provided. This configuration corresponds to the trimming block in the main scanning direction described above. Then, the address counter 48
The most significant bit of 1 is connected to the gate 483 for the horizontal synchronizing signal (MHSYN) and the strobe signal (MSTB). There is. As a result, the start position of data in the other scanning direction is regulated.

The end position of the data in the sub-scanning direction is set by setting a value corresponding to the end position of the data in the address comparator 482. When the address counter 482 counts an address equal to or more than the above value, the address comparator 482 controls the data selector 478 to force the data to zero. As a result, zero data is written in the page memory and the sub-scanning direction is performed.

Next, the LBP interface 410 will be described with reference to FIG. This LBP interface 410 is CPU4
The control signal from 01 is transmitted to LBP300 and LB
It plays the role of transmitting the state of P300 to the CPU 410 and transmitting the image data of the page memories 401 and 405 to the LBP300. That is, an address signal is input from the CPU bus through the address receiver 485 and the address decoder 486, data on the CPU bus or data of the LBP300 is taken into each register according to this address signal, and the contents of each register are read by the CPU 401. Send commands to LBP300, LBP3
Read the state of 00. The printer command register 490 and printer status register are the registers.
A 491, a command register 492, and a status register 493 are provided. The data on the CPU bus is input via the data transceiver 487, the print request signal (PREQ), the print ready signal (PRDY) from the LBP300 is input via the receiver 489, and the print signal (PRT) is input to the driver. It is designed to be output to LBP300 via 495. In addition, the data DAT8 exchanged between the LBP interface 410 and the LBP300 via the transceiver 488.
~ DAT1 has a bus structure, and the status signal (DST
A), it has three states depending on the state of two signals of command signal (DCOM). That is, the status signal of LBP300, LBP300
It has three states: command signal to LBP300 and image signal to LBP300. The timing control circuit 499, which determines any one of the three states, uses the read / write signal from the bus interface 494, the command information from the command register 492, the synchronization signal from the transceiver 498 and the receiver 489, and the like. Based on the above, various signals are output to the LBP300. The image signal from the image bus is the data receiver 496, the data latch circuit 497,
It can be transmitted to the LBP 300 via the bus transceiver 488.

Next, various image editing operations by the apparatus of this embodiment will be described.

<Image Compositing Mode> First, an image compositing mode for composing and forming a plurality of original images on one sheet will be described with reference to FIG. This mode is selected by pressing the combination mode selection key 50 on the first operation panel 6. This key
When 50 is pressed, a plurality of originals are sequentially and continuously read by the scan analog unit 110 and converted into digital signals by the photoelectric conversion unit 120. When the ADF1 is used, a plurality of originals are automatically fed one by one and read one by one. When the ADF1 is not used, the original cover 2 is opened and closed for each original to expose the glass 111. Place the originals on top and read the originals one by one. For example, the images of the originals P ₁ , P ₂ , P ₃ , and P ₄ shown in FIG. 32 are sequentially read one by one as described above. The image thus read is transferred to the image bus via the scanner interface 409, and is an image memory by the address control of the first color page memory address controller 404 which is the write control means in the case of monochrome copying. It is written in the first color page memory 403. At this time, the first color page memory address controller 404 sets the top addresses TP _{1 to} TP ₄ on the image memory 403 according to each original image as shown in FIG. 32, and sets different addresses on the image memory 403. Write each image to.
Then, the contents of the image memory 403 are transferred to the print control unit 370 of the LBP unit 300 via the LBP interface 410, and the first laser diode 314 is driven to emit light, and the photoconductor 3 is driven.
An electrostatic latent image of the composite image is formed on 01. After that, based on the operation of the LBP unit 300 described above, four document images are formed on one sheet T as shown in FIG. With such a combination mode, a plurality of original images can be formed on one sheet by one image forming operation, the copy processing time is shortened, and the sheet consumption is also reduced. For those without ADF1, the exposure glass 11
Images can also be combined by placing multiple originals on 1 at a time, but if you cannot place more than two originals at once, for example, when combining multiple A3 size originals, etc. In this case, this combination mode is convenient. Also,
When this synthesis mode is selected using ADF1, ADF1
The synthesizing operation is performed for each of a plurality of sheets of documents that are successively fed in sequence, and the above operation can be continuously performed until the document absence detection switch 16 detects that there is no document. Is reduced to.

Further, when such a combination mode is selected, it is convenient to reduce a plurality of original images and form them on one sheet. Therefore, the auto magnification mode selection key 15
By using the magnification designation key 158 or the magnification selection key 159, the original image can be reduced in size and written in the image memory 403 to form a composite image on a sheet of a predetermined size. As for image reduction, as described above, data in the main scanning direction is reduced by the image processing unit 456 of the scanner interface 409,
The data in the sub-scanning direction is condensed by changing the scan speed of the carriages 116 and 117.

<Image combining mode + Variable number of combined originals> The image combining mode described above can be performed by fixing the number of originals to be combined with the apparatus, but it is more practical to change the number of originals to be combined. In the apparatus of this embodiment, the first mode as a document number input means after pressing the combination mode selection key 50
By operating the DEN key 56, the number of originals to be combined can be set as desired. Then, a plurality of originals designated by the first numeric keypad 56 are sequentially read and formed on one sheet. The first color page memory address controller 404, which is a writing control unit, sets the top address TP according to the designated number of originals, and designates writing of a plurality of original images to different addresses in the image memory 403. It will be.

<Image combining mode + number of combined originals, variable number of output sheets> It is more practical if the image forming operation for combining a predetermined number of originals on one sheet can be continuously performed on a plurality of output sheets. In the apparatus of this embodiment, the second operation panel 101
A second ten-key 151, which is an output sheet number input means, is provided on the upper side to form the same composite image so that the number of sheets to be output is variable. The laser scanner unit 310 continuously forms the designated number of latent images for each rotation of the photoconductor 301 based on the document image data of a plurality of sheets written in the image memory 403. The copying operation is continuously performed on the paper fed from the upper cassette 321 or the lower cassette 322. Therefore, each original needs to be read only once.

<Designation of Image Extraction Area and Designation of Image Forming Position> For example, for extracting the effective image D ₁ of the document P shown in FIG. 33 and reducing the effective image D ₁ at a predetermined position on the output sheet T by the magnification M to form the image D _2. The operation will be described. Extracted image D of original P
₁ is specified by the coordinate positions X ₁ and Y _{1 of one} corner and A ₁ and B ₁ of the image size. The image forming position of the image D ₂ on the output paper T is specified by the coordinates X ₂ and Y ₂ of one corner of the image P ₂ . Therefore,
As an example for specifying the above coordinates and size, for example,
The information shown in FIG. 34 can be displayed on the LCD 5, and the input of the numerical value corresponding to each information can be requested by the cursor 5B. That is,
When the image extraction mode selection key 51 and the output position designation mode selection key 52 on the first operation panel 6 are selected, the CPU 401
The above display is performed on the LCD 5 under the control of. Then, the information corresponding to the position of the cursor 5B is displayed on the first numeric keypad.
By inputting via 56, the image extraction area and the image forming position can be designated. When the image extraction area is designated as described above, the read image is read by the image data processing unit 456 of the scanner interface 409.
The above-described reduction operation and trimming operation are performed together. Further, when the image forming position is designated, the top address TP is set to a predetermined value by the image memory address controller 404, which is the writing control means, and the address is set to the address on the image memory 403 corresponding to the designated image forming position. Write. After that, if the image forming operation is executed based on the contents of the image memory 403, the image D ₂ as shown in FIG. 33 can be formed on the paper T.

<Image Compositing Mode + Image Forming Position Designation> In this embodiment, the designation of the image forming position described above can be performed even in the image compositing mode. That is, as shown in FIG. 35, the image forming position can be designated for each image of the originals P _{1 to} P _{4 to} be sequentially read, and the images can be rearranged and formed on the paper T. At this time, the composite mode selection key 50
After pressing, the first ten key 56 is operated to set the number of originals to be combined. Then, when the image forming position designation mode selection key 52 is pressed, the screen shown in FIG. 34 is displayed on the LCD 5. If the image extraction mode selection key 51 is not selected, the information regarding "READ" is not displayed in FIG. Then, according to this display, the first ten-key pad 56 is operated to specify the image forming position coordinates X ₂ and Y ₂ for each of the originals P _{1 to} P ₄ . By such designation, the page memory address controller 404, which is the writing control means, determines the top address of each original image with respect to the image memory 40 at each coordinate
Determine according to X ₂ , Y ₂ . As a result, as shown in FIG. 35, the images can be combined and formed at a position on the paper T different from the original input order.

If there are multiple images as shown in FIG. 36 to <a single extraction region division designation of the document image> single document P, extracting respectively the respective images on different paper T _1, T _2, T ₃ It is a mode to form. At this time, the image extraction mode selection key 51 is pressed to display the "READ" display shown in FIG.
The operation is performed on D5, and the coordinates X1, Y1 and sizes A1, B1 are input through the first ten-key pad 56 to specify the extraction area of the image "A" of the original P. Then, for example, the image extraction mode selection key again
Similarly, the user presses 51 to sequentially specify the extraction regions of the images "B" and "C" in the document P. When the division is designated in this manner, the CPU 401 drives and controls the scanner unit 110 via the scanner interface 409, and continuously reads the image of the same original P by the number of divisions. Then, the page memory address controller 404, which is the writing control means, trims the image according to the order designated by division for each reading operation, and writes the extracted image in the memory 403. Furthermore, LBP unit 300
This based on the contents of the image memory 403 performs sequential image forming operation on a different paper, extraction image shown in FIG. 36, "A", "B", the paper T ₁ that different "C", respectively, which in,
It can be formed on T ₂ and T ₃ . It is also possible to specify the image forming position and / or select the reduction / enlargement mode together with the division specification.

<Auto Magnification Mode> Next, a mode for automatically setting the image copy magnification based on the operation of the auto magnification mode selection key 157 provided on the second operation panel 101 will be described.

In order to automatically set the copy magnification, it is necessary to detect at least the size of the original image and the size of the output paper in advance. When the ADF 1 is used, the document width detection switch 14 and the document switch 21 detect the vertical and horizontal sizes of the document. Further, when the image extraction mode is selected, it can be detected by inputting the sizes A1 and B1 of the image extraction area shown in FIG. On the other hand, the output paper size is
It is detected by the upper cassette size detection switch 325 or the lower cassette size detection switch 328 which detects the paper size by determining the type of the lower cassettes 321 and 322. Then, the CPU 401 can input the size information via the CPU bus and detect the sizes of the original and the output paper in advance. Then, the auto magnification mode selection key 157
When is pressed, the CPU 401 can calculate the copy magnification from the size information. Then, the CPU 401 controls the scan speed of the carriages 116 and 117 in the scanner unit 110 via the scanner interface 409 based on the copy magnification, and performs the enlargement or reduction operation in the sub-scanning direction. Further, the information of the copy magnification is sent to the image data processing unit 456 of the scanner interface 409 to perform the enlargement / reduction operation in the main scanning direction. In this way, the image forming operation based on the automatic magnification mode is performed. Also,
Such an automatic magnification mode can also be performed in combination with the above-mentioned combination mode. In the combination mode, the copy magnification is automatically set for each original to be combined.

<Combining Mode + Original Contour Erasing Mode> When a plurality of original images are formed on one sheet, the contour lines of the respective originals may be formed on the sheets, resulting in a poor-looking copy. . In the apparatus of this embodiment, by pressing the image erasing mode selection key 53 and designating the contour area with the first numeric keypad 56, the image data of this area can be forcibly set to zero on the image memory 403. For example, as shown in FIG. 37, the outline area of the original,
When erasing, the CPU 401 supplies XN1, XN2, YN1, YN2 and top addresses TP _{1 to} TP ₄ to the command port 421 of the page memory attritor controller 404 which is the write control means shown in FIG. , Are sequentially set in the registers 423, 430, and 432.

To clear all the data in the area, set TP ₁ , XN1, and YN1 in the registers 423, 430, and 432, respectively, and set the all clear command assigned to the specific bit of the command port 421 to "1". The operation is started. Page memory address controller 40
4 first goes to the image bus via the address transceiver 427
The address of TP ₁ is output, and at the same time, the signal on the image bus that invalidates the data bus is set to “1”, and the write signal to the image memory 403 is output. next,
A write signal is output while sequentially updating the address from the address transceiver 427, and when this operation is repeated XN1 times, a carry is output from the XN counter 431.
Then, only one YN counter 433 is updated and the address is set to the value of TP ₁ + XW. The above operation is performed until the YN counter 433 counts YN once, and when this value is counted, a carry is output from the YN counter 433 and the all clear operation of the area is completed. region~
Similarly, TP ₂ to TP ₄ , XN1, XN2, YN1 and YN2 can be set. Further, in the composite mode, the contour area of each document can be erased on the image memory 403 by setting the contour area of each document with the top address and XN, YN.

<Contour Line Writing Mode> After the contour lines of the originals to be combined are erased as described above, the contour lines of the respective originals can be newly written on the image memory 403. At this time, the image deletion mode selection key 5
3, After specifying the contour area to be erased with the 1st key 56,
Bordering mode selection key as contour writing mode selection means
Press 54. Then, after the above-mentioned contour area erasing operation, a new contour line is written in this area, that is, the contour line writing position is TP, XN, YN from the CPU 401 to each register via the command port 421. Set
Further, the CPU 401 programs the data address and the data length in which the data to be written is stored in the DMA controller 411 shown in FIG. 26, and the DMA operation is enabled. DMA controller 411 is the designated image memory 403
The upper address is automatically accessed, and "1" is written in the corresponding address on the contour line to perform framing.

<Paging Mode> The DMA controller 411 described above can write various data on the image memory and is not limited to the contour line of the document. For example, a page code may be attached to the output paper. The number as the page code is stored in, for example, a lower memory of the program memory 402, and the DMA controller 411 can read this page code information from the program memory 402 and write it in the image memory 403. There are two types of page code writing modes. First, by pressing the paged mode selection key 55 and the "input order" selection key 55A on the first operation panel 6, as shown in FIG. 38, image formation of each document in the combination mode is performed. In this mode, a page code is attached to the position corresponding to the area. The other one is a mode in which the page code is added in the output order of the paper as shown in FIG. 39 by pressing the page addition mode selection key 55 and the "output order" selection key 55B.

In the former "input order" mode, the CPU 401 can detect the top addresses TP _{1 to} TP ₄ and the page code formation area sizes XN and YN shown in FIG. 38 from the size of the output paper and the number of composite originals. Command data 42 to each register 423,430,432 of page memory address controller 404
The page code can be set on the image memory 403 by the DMA controller 411.

Even in the latter "output order" mode, the top address TP of the page code formation area and the size XN, Y
N can be detected, and these data are set to each register 423, 430, 432 via the command port 421, and the DMA controller
By the operation of 411, page codes can be added in the output order.

Incidentally, the above-mentioned “input order” mode and “output order” mode can be performed together, and further, the image forming position designation mode, trimming or enlargement / reduction mode can be performed together.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the paper of the present invention.

As described above, according to the present invention, the scanning length of the laser beam is corrected by changing the time width of the video clock corresponding to one dot on the photosensitive member. The adjustment for matching the scanning lengths of the beams can be easily performed without requiring the complicated work of matching the optical path lengths by adjusting the positions of the optical components as in the conventional case.

[Brief description of drawings]

FIG. 1 is an external perspective view of an apparatus according to an embodiment of the present invention, FIG. 2 is a main control block diagram of the apparatus according to the present invention, FIG. 3 is a schematic cross-sectional view of the apparatus according to the present invention, and FIGS. ) Are partially cutaway plan views and schematic cross-sectional views of the document placing table, FIG. 5 is a control block diagram of the scanner unit, and FIG. 6 is a schematic explanatory diagram for explaining main timing signals of document reading by the scanner unit. 7 is a schematic sectional view of a laser scanner unit, FIGS. 8 (A) and 8 (B) are schematic explanatory views showing an arrangement example of an exposure portion of a photoconductor, and FIGS. 9 (A) and 9 (B).
(C) is a schematic explanatory view for explaining a defect when two-color printing is carried out by the contact development system, and FIG. 10 is a schematic explanatory view for explaining mixing of toner when two-color printing is carried out by the contact development system. The figure is a schematic cross-sectional view showing an example of a developing device by a non-contact developing method,
12 (A) to (D) are explanatory diagrams showing the principle of color mixture generation in multicolor printing, and FIGS. 13 (A) to (D) are schematic diagrams for explaining the principle of solving the color mixture generation. Explanatory drawing, FIG. 14 is a schematic perspective view of the laser scanner unit, FIG. 15 (A) is an explanatory view showing the deviation of the scanning start point of the laser beam, and FIG. 15 (B) shows the discrepancy of the scanning length of the laser beam. Explanatory diagram showing
FIG. 16 is a block diagram showing an LBP unit and an LBP interface, FIG. 17 is a schematic explanatory diagram showing signals between the LBP unit and the LBP interface, and FIG. 18 is a block showing an example of a print control unit of the LBP unit. FIGS. 19 and 20 are timing charts for explaining the correction operation of the deviation of the laser beam scanning start point in the print control unit shown in FIG. 18, and FIG. 20 is the horizontal synchronization signal formation in the sub-scanning direction in the print control unit. A timing chart for explaining the operation, FIG. 21 is a block diagram showing another example of the print control unit, FIG. 22 is a detailed block diagram of the quaternary counter and selector of the print control unit shown in FIG. 21, and FIG. Is a timing chart of the operation for correcting the discrepancy of the scanning lengths of the laser beams, FIG. 24 is a schematic explanatory view of the first and second operation panels, FIG. 25 is a block diagram of the page memory address controller, and FIG. 26 is DMA. Block diagram of controller, Figure 27 is block diagram of image memory, Figure 28 is block diagram of scanner interface, and Figure 29 is 28
The detailed block diagram of the image data processing unit shown in FIG. 30 and FIGS. 30 (A) and 30 (B) respectively explain the enlargement and reduction of data in the image data processing unit, and FIG. Timing chart for writing to memory, No. 30
FIG. (B) is a timing chart at the time of reading from the line memory, FIG. 31 is a block diagram of the LBP interface, and FIG. 32 is a schematic explanatory diagram explaining an image combining mode,
FIG. 33 is a schematic explanatory diagram showing various information for image extraction designation and image formation position designation, and FIG. 34 is a schematic explanatory diagram showing a display example requesting information for inputting the information shown in FIG. 33.
FIG. 35 is a schematic explanatory view for explaining the image forming position designation mode of the combination mode, FIG. 36 is a schematic explanatory view for explaining the division designation mode of the image extraction area, and FIG. 37 is a mode for erasing the outline of the document. FIG. 38 is a schematic explanatory view for explaining a mode in which page codes are attached corresponding to the document input order in the composite mode, and FIG. 39 is a schematic explanatory view for explaining a mode in which page codes are attached in the output order of the output paper. Is. 240, 241 ... Video clock generation circuit, 242 ... Scan length correction means, 243 ... Reference clock generation circuit, 230 ... Secreter, 301
... photoreceptor, 302,304 ... charging means, 303,305 ... developing means, 31
1,314,316,318,319,310 ... Laser scanner unit, 31
2,313,315,317,319,

Claims (4)

[Claims] 1. A charging means for charging a photoconductor, an image forming means for scanning the photoconductor charged by the charging means with a laser beam to form an electrostatic latent image on the photoconductor, and an image. In a laser printer for performing various types of printing by arranging a plurality of forming means and developing means around the photoconductor, a plurality of laser printers are provided corresponding to the plurality of image forming means, and from the scanning start point of each laser beam. A video clock generating means for generating a video clock for the scanning end point, and a scanning length correcting means for correcting the scanning length of the laser beam by changing the time width of the video clock generated by the video clock generating means. A laser printer comprising: 2. A scanning length correcting means selects a reference clock generating circuit for generating a plurality of reference clocks corresponding to a plurality of scanning lengths, and a plurality of reference clocks from the reference clock generating circuit for the video clock generating circuit. Claim 1 which comprises a selector for outputting
A laser printer according to item. 3. The laser printer according to claim 2, wherein the reference clock generation circuit makes the time width of each reference clock variable. 4. The reference clock generation circuit according to claim 3, wherein the time width of the reference clock is variable at a time corresponding to 1 / n (n is an integer of 2 or more) dots. Laser printer.