JP5454033B2 - Image forming apparatus and image forming method - Google Patents

Description

  The present invention relates to an image forming apparatus capable of forming an image and an image forming method.

  In a conventional image forming apparatus, for example, registration in the sub-scanning direction is performed at the timing until the image forming operation starts with a system operation start signal generated based on a detection signal of a registration sensor that detects the position of a recording medium such as transfer paper. It is adjusted.

  For example, one line in the sub-scanning direction is controlled by performing control in units of line cycles using a synchronization detection signal that is a reference signal of the writing control unit, and controlling the timing of the sub-scanning start reference position according to the synchronization detection signal. A tandem color image forming apparatus capable of unit color matching control is disclosed (see Patent Document 1).

  However, in Patent Document 1 described above, since the synchronization detection signal and the system operation start signal are completely asynchronous, there are a plurality of image sub-scanning positions on the recording medium (transfer sheet) depending on the timing of the system operation start signal. In some recording media, a maximum of one line may be misaligned.

  On the other hand, in recent years, in order to improve the printing speed of the image forming apparatus, a plurality of lines (for example, 8 lines) are scanned in one scan by an optical deflector such as a polygon mirror apparatus, so that each scan is performed. Those that form electrostatic latent images in units of multiple lines have come into practical use. As described above, in the image forming apparatus that scans 8 lines in one scan, there is a problem that the shift in the sub-scanning position between the plurality of recording media is 8 lines at the maximum.

  The present invention has been made in view of the above, and an image forming apparatus capable of reducing a shift in sub-scanning position between a plurality of recording media when forming an electrostatic latent image in units of multiple lines for each scan. It is another object of the present invention to provide an image forming method.

In order to solve the above-described problems and achieve the object, an image forming apparatus according to the present invention emits a light beam by being driven and controlled by an image processing unit that performs image processing of image data to be formed. A plurality of light sources, a scanning unit that simultaneously scans a plurality of light beams corresponding to a plurality of lines in the main scanning direction, and the plurality of light beams carry an electrostatic latent image of the image data of the plurality of lines in one scan. When the image forming unit to be formed on the body and the system operation start signal instructing the start of the image forming operation are received, a sub-scanning start reference signal indicating a reference for starting image formation in the sub-scanning direction is sent to the image processing unit. And a writing control unit that starts driving operation by driving the light source when the image data is received from the image processing unit, and the writing control unit has a reference color Includes some standard colors It provided plural in correspondence with the number of colors, the write control unit further timing of receiving the system operation start signal, among the divided areas obtained by dividing a scanning period of the main scanning direction into a plurality of any of wherein the first determination section for determining whether the divided region, the pre-Symbol sub scanning start reference signal and a signal generator outputting to the image processing unit, the writing control unit corresponding to the reference color The writing operation start signal for instructing the start of the writing operation at the same timing in the scanning cycle in the main scanning direction determined in advance for each of the divided regions from which the system operation start signal is received. A sending unit for sending to the control unit, and each of the write control units further determines in which divided region the divided region has the timing of receiving the write operation start signal. A determination unit, and the signal generation unit outputs the sub-scanning start reference signal at a timing delayed by a time corresponding to a predetermined number of lines for each of the divided regions from which the write operation start signal is received. The image processing unit outputs to the image processing unit, and the image processing unit further transfers the image data subjected to the image processing to the writing control unit when the sub-scanning start reference signal is received.

The image forming method of the present invention is an image forming method executed by an image forming apparatus, wherein the image forming apparatus is driven and controlled to emit a light beam, and the light source is driven. A scanning unit that simultaneously scans a plurality of light beams corresponding to a plurality of lines in the main scanning direction under control, and an electrostatic latent image of a plurality of lines of image data is formed on the image carrier in one scan by the plurality of light beams. An image forming unit, and the image processing unit includes an image processing step for performing image processing of the image data, and a plurality of writings corresponding to each of a plurality of colors including a reference color that is a reference color When the control unit receives a system operation start signal instructing start of an image forming operation, the control unit sends a sub-scanning start reference signal indicating a reference for starting image formation in the sub-scanning direction to the image processing unit, and the image processing A write control step of driving the light source to start a write operation when the image data is received from the image data, and the write control step further includes a timing at which the system operation start signal is received. A first determination step of determining which of the divided areas among the divided areas obtained by dividing the scanning cycle in the main scanning direction into a plurality of divided areas; and the writing control unit corresponding to the reference color A write operation start signal for instructing the start of a write operation is sent to the write control unit for each color at the same timing in a scanning cycle in the main scanning direction that is predetermined for each of the divided regions from which the operation start signal has been received. The sending step to send and each of the write control units determines in which of the divided areas the timing at which the write operation start signal is received. And 2 determination step, at a timing delayed by a time corresponding to the number of lines that are predetermined for each of the said divided area which the writing operation start signal is received, outputs the sub scanning start reference signal to the image processing unit A signal generating step, wherein the image processing step further transfers the image-processed image data to the writing control unit when the sub-scanning start reference signal is received. .

  According to the present invention, when forming an electrostatic latent image in units of multiple lines for each scan, there is an effect that the shift of the sub-scanning position between the plurality of recording media can be reduced.

FIG. 1 is a schematic diagram showing a mechanical configuration of the image forming apparatus according to the present embodiment. FIG. 2 is a configuration diagram of a VCSEL incorporated in the optical device according to the present embodiment. FIG. 3 is a schematic perspective view when the optical device including the VCSEL exposes the photosensitive drum. FIG. 4 is a diagram illustrating a functional configuration of the image forming apparatus according to the present embodiment. FIG. 5 is a more detailed functional block diagram of GAVD. FIG. 6 is a block diagram showing a functional configuration of the output data control unit of the GAVD according to the present embodiment. FIG. 7 is an explanatory diagram showing a timing chart of job start control of the image forming apparatus according to the present embodiment. FIG. 8 is an explanatory diagram showing a timing chart of job start control of the image forming apparatus according to the present embodiment.

  Exemplary embodiments of an image forming apparatus and an image forming method according to the present invention are explained in detail below with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram showing a mechanical configuration of the image forming apparatus according to the present embodiment. The image forming apparatus 100 according to the present embodiment includes an optical device 102 including an optical element such as a VCSEL (Vertical Cavity Surface Emitting LASER) 200 (see FIG. 2 and FIG. 3, not shown in FIG. 1), a polygon mirror 102a, and the like. The image forming unit 112 includes a photosensitive drum as a carrier, a charging device, a developing device, and the like, and a transfer unit 122 including an intermediate transfer belt. In the embodiment shown in FIG. 1, the light beam (laser beam) emitted from the VCSEL 200 is once condensed by a first cylindrical lens (not shown) and deflected to the reflection mirror 102b by the polygon mirror 102a. .

  Here, the VCSEL 200 is a surface emitting semiconductor laser in which a plurality of semiconductor laser elements (light sources) are arranged in a lattice pattern on the same chip. Various techniques are known as an image forming apparatus using such a VCSEL 200, and the VCSEL 200 is incorporated in the optical device 102 of the image forming apparatus 100 according to the present embodiment with the same configuration as those known techniques. It is. FIG. 2 is a configuration diagram of the VCSEL 200 incorporated in the optical device 102 of the present embodiment. As shown in FIG. 2, the VCSEL 200 of the present embodiment constitutes a semiconductor laser array in which a plurality of light sources 1001 are arranged in a lattice pattern. The arrangement direction of the plurality of light sources 1001 is provided to be inclined at a predetermined angle θ with respect to the rotation axis of the polygon mirror 102a as a deflector.

  In FIG. 2, the vertical arrangement direction of the light sources is a to c and the horizontal arrangement direction is 1 to 4. For example, the upper left light source 1001 in FIG. 2 is represented as a1. When the light source 1001 is arranged with the polygon mirror angle θ, the light source a1 and the light source a2 are exposed at different scanning positions, and one pixel (one pixel) is constituted by the two light sources, that is, in FIG. Consider a case where one pixel is realized with two light sources. For example, if one pixel is composed of two light sources a1 and a2, and one pixel is composed of two light sources a3 and a4, a pixel as shown at the right end of FIG. When the vertical direction in the figure is the sub-scanning direction, it is assumed that the distance between the centers of the pixels constituted by the two light sources is equivalent to 600 dpi. At this time, the center distance between the two light sources constituting one pixel is equivalent to 1200 dpi, and the light source density is twice the pixel density. Therefore, by changing the light quantity ratio of the light source constituting one pixel, the center of gravity of the pixel can be shifted in the sub-scanning direction, and high-precision image formation can be realized.

  In the image forming apparatus 100 according to the present embodiment, the optical device 102 uses a post-object type device that does not use an fθ lens. In the illustrated embodiment, the light beams L are respectively emitted by the number of VCSELs 200 corresponding to each color of cyan (C), magenta (M), yellow (Y), and black (K). Each light beam L is reflected by the reflection mirror 102b and condensed again by the second cylindrical lens 102c to expose the photosensitive drums 104a, 106a, 108a, and 110a.

  In the conventional color image forming apparatus, four color images are formed by four independent optical devices (optical units). However, in the image forming device 100 of the present embodiment, as described above, a single optical device 102 is used. As a result, four color images of cyan (C), magenta (M), yellow (Y), and black (K) are formed.

  Further, in the optical device 102 of the present embodiment, the polygon mirror 102a is arranged in the center of the optical device 102, and the four color light beams are deflected in the main scanning direction by one polygon mirror 102a.

  A VCSEL 200, optical components such as a mirror and a lens, and a synchronization detection device 210 (described later) are arranged symmetrically with respect to the polygon mirror 102a as a center, and the optical paths of light beams of two colors are laid out on the left and right. The polygon mirror 102a is used to deflect the four color light beams. In the present embodiment, magenta (M) and cyan (C) optical paths are laid out on the left side of the polygon mirror 102a, and yellow (Y) and black (K) optical paths are laid out on the right side.

  Since the irradiation of the light beam L is performed using a plurality of optical elements as described above, timing synchronization is performed in the main scanning direction and the sub-scanning direction. Hereinafter, the main scanning direction is defined as the light beam scanning direction, and the sub-scanning direction is defined as a direction orthogonal to the main scanning direction.

  The image forming unit 112 includes a magenta (M) color component image forming unit 104, a cyan (C) color component image forming unit 106, a yellow (Y) color component image forming unit 108, and a black (K) color component image forming. Part 110. The image forming units 104, 106, 108, and 110 for the respective colors mainly include photosensitive drums 104a, 106a, 108a, and 110a, chargers 104b, 106b, 108b, and 110b, and developing units 104c, 106c, 108c, and 110c, respectively. In preparation.

  Each of the photosensitive drums 104a, 106a, 108a, and 110a includes a photoconductive layer including at least a charge generation layer and a charge transport layer on a conductive drum such as aluminum. The photoconductive layer is disposed corresponding to each of the photosensitive drums 104a, 106a, 108a, and 110a, and is charged with a surface charge by the chargers 104b, 106b, 108b, and 110b including a corotron, a scorotron, or a charging roller. Is granted.

  The electrostatic charges imparted on the photosensitive drums 104a, 106a, 108a, 110a by the respective chargers 104b, 106b, 108b, 110b are imagewise exposed by the light beam L to form an electrostatic latent image. The electrostatic latent images formed on the photoconductive drums 104a, 106a, 108a, and 110a are developed by the developing devices 104c, 106c, 108c, and 110c including a developing sleeve, a developer supplying roller, a regulating blade, and the like. Is formed.

  The developer images carried on the photosensitive drums 104a, 106a, 108a, and 110a are transferred onto the intermediate transfer belt 114 that moves in the direction of arrow A by the conveying rollers 114a, 114b, and 114c. The intermediate transfer belt 114 is conveyed in a state where C, M, Y, and K developers are carried.

  On the other hand, the uppermost image receiving material 124 such as high-quality paper or plastic sheet placed on the paper feed unit (not shown) is picked up by a pair of paper feed rollers (not shown) and conveyed in the downstream direction B. Is done. The image receiving material 124 conveyed from the paper supply unit is detected by the registration sensor SS and then abuts against the paper supply registration roller 134 and stops. Further, the image receiving material 124 is transferred to the transfer roller 13 that is in contact with the conveying roller 114b by the paper feeding registration roller 134 at the timing when it is aligned with the multicolor developer image (full color toner image) transferred on the surface of the intermediate transfer belt 114. Is sent out. Then, the transfer roller 13 transfers the multicolor developer image (full color toner image) formed on the surface of the intermediate transfer belt 114 onto the surface.

  The transferred image receiving material 124 is sent to the fixing device 120, where the full color toner image transferred onto the surface of the image receiving material 124 is thermally fixed, conveyed to a paper discharge unit (not shown), and discharged.

  An alignment pattern reading sensor 15 provided in the vicinity of the conveyance roller 114 c is for reading an alignment pattern formed on the surface of the intermediate transfer belt 114. This alignment pattern is for detecting a shift in the sub-scanning direction of the color component images formed by the respective color component image forming units 104, 106, 108, and 110, respectively.

  FIG. 3 is a schematic perspective view when the optical device 102 including the VCSEL 200 exposes the photosensitive drum 104a. The light beam L emitted from the VCSEL 200 is collected by the first cylindrical lens 202 used for shaping the light beam bundle, passes through the reflection mirror 204 and the imaging lens 206, and is then deflected by the polygon mirror 102a. . The polygon mirror 102a is rotationally driven by a spindle motor that rotates several thousand to several tens of thousands. The light beam L reflected by the polygon mirror 102a is reflected by the reflection mirror 102b and then reshaped by the second cylindrical lens 102c to expose the surface of the photosensitive drum 104a.

  In order to synchronize the scanning start timing of the light beam L in the sub-scanning direction, a reflection mirror 208 is disposed. The reflection mirror 208 reflects the light beam L to the synchronization detection device 210 including a photodiode or the like before starting scanning in the sub-scanning direction. When detecting the light beam, the synchronization detection device 210 generates a synchronization signal to start sub-scanning. With this synchronization signal, processing such as generation of a drive control signal for the VCSEL 200 is synchronized with scanning in the sub-scanning direction.

  The VCSEL 200 is driven by an input pulse signal input from a GAVD 310 (to be described later). As will be described later, the light beam L is exposed at a position corresponding to a predetermined image bit of the image data, and the electrostatic latent image is transferred onto the photosensitive drum 104a. Form an image. The configuration excluding the VCSEL 200 and the photosensitive drum 104a in FIG. 3 is a scanning unit.

  FIG. 4 is a diagram illustrating a functional configuration of the image forming apparatus 100 according to the present embodiment. As shown in FIG. 4, a scanner 301 and a control unit 300 are provided. The control unit 300 includes an image acquisition unit 302, a printer unit 308, and an engine control unit (main control unit) 330. The image acquisition unit 302 acquires an image signal from the scanner 301 serving as an image reading unit and performs image processing. More specifically, the image acquisition unit 302 is configured to include a VPU 304 and an IPU 306. The VPU 304 sends a scan start command signal for instructing the scanner 301 to start scan processing. In addition, the VPU 304 performs A / D conversion on the image signal input from the scanner 301 to perform black offset correction, shading correction, and pixel position correction. The IPU 306 mainly performs image processing for digitally converting the acquired image signal as image data from the RGB color system to the CMYK color system. The image data processed by the image acquisition unit 302 is sent from the IPU 306 to the printer unit 308 as digital data.

  The printer unit 308 generates a current (light emission current, threshold current, bias current) for driving a semiconductor laser element as a light source by a GAVD 310 that is a VCSEL controller that controls driving of the VCSEL 200 and an input pulse signal generated by the GAVD 310. The LD driver 312 supplies each generated current to the semiconductor laser element, and the VCSEL 200 mounts the two-dimensionally arranged semiconductor laser element. The GAVD 310 of this embodiment divides pixel data for the image data sent from the image acquisition unit 302 so as to correspond to the spatial size of the light beam emitted from the semiconductor laser element of the VCSEL 200, and performs high resolution processing. Execute.

  The image acquisition unit 302 and the printer unit 308 are connected to the engine control unit 330 via the system bus 316, and the image acquisition and image processing by the image acquisition unit 302 and the printer unit 308 are performed according to instructions from the engine control unit 330. The image formation by is controlled. An engine control unit 330 that controls the entire image forming apparatus includes a central processing unit (hereinafter referred to as a CPU) 320 and a RAM 322 that provides a processing space used by the CPU 320 for processing. The CPU 320 can be any CPU known so far, for example, CISC (Complex Instruction Set Computer) such as PENTIUM (registered trademark) series or compatible CPU, RISC (Reduced Instruction Set Computer) such as MIPS, etc. Can be used. The CPU 320 receives a command from the user via the interface 328, calls a program module that executes processing corresponding to the command, and executes processing such as copying, facsimile, scanner, and image storage. Further, the engine control unit 330 includes a ROM 324, and stores initial setting data, control data, programs, and the like of the CPU 320 so that the CPU 320 can use them. The image storage 326 is configured as a fixed or detachable memory device such as a hard disk device, an SD card, or a USB memory, stores image data acquired by the image forming apparatus 100, and can be used for various processes by the user. Yes.

  When driving the printer unit 308 for the image data acquired by the image acquisition unit 302 to output an image as an electrostatic latent image on the photosensitive drum 104a or the like, the CPU 320 controls the main scanning direction and sub-scanning position of the image receiving material 124. Execute. The CPU 320 outputs a start signal to the GAVD 310 when starting scanning in the sub-scanning direction. When the GAVD 310 receives a start signal from the CPU 320, the GAVD 310 sends a notification signal indicating that the start signal has been received to the VPU 304. Upon receiving this notification signal, the VPU 304 sends a scan start command signal for instructing the scanner 301 to start scan processing in the sub-scanning direction. The image signal obtained by the scan processing by the scanner 301 is sent to the VPU 304, and after the above-described image processing is performed by the VPU 304, it is sent to the IPU 306 as image data. The IPU 306 performs the above-described digital conversion on the image data, and then sends the image data to the GAVD 310. The GAVD 310 once inputs the image data received from the IPU 306 to the memory 340 (see FIG. 5), and then the GAVD 310 processes the image data stored in the memory 340 and outputs the processed image data to the LD driver 312. . When the LD driver 312 receives image data from the GAVD 310, the LD driver 312 generates a drive control signal for the VCSEL 200. Thereafter, the LD driver 312 sends this drive control signal to the VCSEL 200 to turn on the semiconductor laser element of the VCSEL 200. The LD driver 312 drives the semiconductor laser element using PWM control or the like. The VCSEL 200 described in the present embodiment includes 8 channels of semiconductor laser elements, but the number of channels of the VCSEL 200 is not limited.

  FIG. 5 shows more detailed functional blocks of the GAVD 310. The GAVD 310 includes a memory 340 such as a FIFO buffer that receives the synchronization signal DETP_N and stores and stores the image data sent from the IPU 306. The GAVD 310 receives the image data transmitted from the IPU 306 in the first-in / first-out manner. The data is passed to the processing unit 342. The image processing unit 342 reads image data from the memory 340, and executes processing such as image data resolution conversion, semiconductor laser element channel allocation, and image bit addition / deletion. In the image data, a position where the photosensitive drum 104a is exposed is defined by a main scanning line address value defined in the main scanning direction and a sub scanning line address value defined in the sub scanning direction.

  The output data control unit 344 performs processing based on the synchronization signal DETP_N generated by detecting the light beam emitted by the VCSEL 200 with the synchronization detection device 210. Further, the output data control unit 344 uses a system operation start signal STTRIG_N (described later) as a trigger, an image transfer request signal MLSYNC_N for causing the image processing unit 342 to transfer raster data, and a reference for starting printing in the sub-scanning direction. The sub-scanning start reference signal MFSYNC_N, which is a signal indicating the above, is output. Further, the output data control unit 344 sends an input pulse signal for driving control of the VCSEL 200 and image data to be written to the LD driver 312.

  FIG. 6 is a block diagram showing a functional configuration of the output data control unit 344 of the GAVD 310 according to the present embodiment.

  As shown in FIG. 6, the output data control unit 344 includes write control units 70M (magenta), 70C (cyan), 70Y (yellow), and 70K (black: black) for each color. The operation modes of the write control units 70M, 70C, 70Y, and 70K of the output data control unit 344 are set by the engine control unit 330. In addition, the engine control unit 330 performs various settings for the write control units 70M, 70C, 70Y, and 70K of the output data control unit 344, and sets a reference color (reference color) among the four colors. . As the reference color, the color at which image formation starts first is set. In this embodiment, magenta (M) at which image formation is started first is set as a reference color (see FIG. 1).

  In this embodiment, magenta is set as the reference color. However, the present invention is not limited to this, and the magenta component image forming unit 104, the cyan component image forming unit 106, the yellow component image forming unit 108, and the like. In the black component image forming unit 110, as described above, the first color to start image formation can be determined as the reference color.

  As shown in FIG. 6, the write control units 70M, 70C, 70Y, and 70K are each independently a synchronization signal control unit 74, an MLSYNC generation unit 73, a delay line control unit 72, and a signal generation unit MFSYNC. It mainly includes a generation unit 71, a delay scan control unit 75 that is a transmission unit, a writing image development unit 76, and a second determination unit 62. In the present embodiment, the writing control unit 70M corresponding to the reference color further includes a first determination unit 61. The write controllers 70M, 70C, 70Y, and 70K include a sub-scanning delay scan register mfdly_r and a sub-scanning delay line register mfsyncpos_r (all not shown). The sub-scanning delay scan register mfdly_r and the sub-scanning delay line register mfsyncpos_r are connected to the engine control unit 330 by a register READ / WRITE line (not shown).

  In this embodiment, the write control units 70M, 70C, 70Y, and 70K are realized by hardware using these units and registers. However, a CPU is provided in the write control units 70M, 70C, 70Y, and 70K. And the functions of the write control units 70M, 70C, 70Y, and 70K may be realized by a program executed by the CPU.

  Below, each structure is demonstrated along the procedure of a process. The engine control unit 330 outputs the system operation start signal STTRIG_N to the reference color magenta (M) at the timing when the transfer sheet position is detected by the registration sensor SS provided at the position of the sheet feeding registration roller 134. Output to 70M. Note that color components other than the reference color are set as subordinate colors. Here, the system operation start signal STTRIG_N is a signal generated from the registration sensor SS based on the detection signal and indicating the start of the printing operation.

  In the present embodiment, the write control unit 70M is a magenta color write control unit that is a reference color, and therefore holds (latches) the falling edge of the system operation start signal STTRIG_N received from the engine control unit 330. The write control unit operation start signal STOUT_N is output to the reference color write control unit 70M and the subordinate color write control units 70C, 70Y, and 70K at specific timings where the scan management of each color is performed. Here, the specific timing at which the write control unit operation start signal STOUT_N is output is a timing at which all color synchronization signals DETP_N and scan synchronization signals lcrl (described later) are not generated.

  At this time, the first determination unit 61 of the writing control unit 70M divides the scanning cycle (main scanning cycle) in the main scanning direction into two when the timing at which the system operation start signal STTRIG_N is received from the engine control unit 330. It is determined which of the divided areas is present. Specifically, for example, the determination is made based on whether or not the counter value cleared by the scan synchronization signal lcrl is larger than a predetermined value. Then, the write control unit 70M changes the timing for outputting the write control unit operation start signal STOUT_N according to the timing at which the system operation start signal STTRIG_N is received.

  In the present embodiment, when the timing at which the system control start signal STTRIG_N is received is the first half of the main scanning cycle, the writing control unit 70M sends the writing control unit operation start signal STOUT_N to 1 / of the main scanning cycle. 4 and when the timing at which the system operation start signal STTRIG_N is received is in the second half of the main scanning period, the write control unit operation start signal STOUT_N is output to a position 3/4 of the main scanning period. .

  In each color write control unit 70M, 70C, 70Y, 70K, the delay scan control unit 75 counts the scan synchronization signal lcrl using the write control unit operation start signal STOUT_N as a trigger. Here, the scan synchronization signal lclr is a signal generated by the synchronization signal control unit 74. Specifically, the scan synchronization signal lcrl is a synchronization signal control unit for the write control units 70M, 70C, 70Y, and 70K with reference to the synchronization signal DETP_N detected by the synchronization detection device (detection sensor) 210 of the optical device 102. This signal generates one pulse on one surface of the polygon mirror 102a whose timing is controlled at 74.

  Further, the second determination unit 62 of each color write control unit 70M, 70C, 70Y, 70K receives the write control unit operation start signal STOUT_N at a position (first half) of the main scanning cycle. It is determined whether or not it is in the 3/4 position (second half). For example, the second determination unit 62 determines whether the timing is the first half or the second half of the main scanning cycle based on whether the counter of the scan synchronization signal lcrl is greater than a predetermined value. When the counter of the scan synchronization signal lcrl is smaller than the predetermined value, it is determined that the counter is ¼ of the main scanning period, which is the first half. It is determined that the current position is 3/4 of the scanning cycle.

  The engine control unit 330 detects a position in the sub-scanning direction for forming an electrostatic latent image of each color image transferred onto the intermediate transfer belt 114 in advance by a program executed by the CPU 320, and uses the detected position as a reference. The delay timing for forming cyan, yellow and black from the color magenta is calculated. Here, the detection of the position in the sub-scanning direction by the engine control unit 330 is performed by the alignment pattern reading sensor 15 based on the reading state of the alignment pattern of each color, for example.

  Further, the engine control unit 330 adds the transport delay time calculated from the positional relationship between the transfer position of the registration sensor SS that detects the transfer paper position and the reference color magenta to the calculated delay timing. Then, the engine control unit 330 sets the image formation delay time of each color as the addition result to the delayed sub-scanning number that is the number of scans (scanning number) in the sub-scanning direction and the delay sub-scanning that is the number of lines in the sub-scanning direction. Replace with the number of lines. Then, the engine control unit 330 sends the value of the number of delayed sub-scans for each color to the sub-scan delay scan register mfdly_r of each color write control unit 70M, 70C, 70Y, 70K via the register READ / WRITE line. Then, the value of the number of delayed sub-scan lines for each color is set in the sub-scan delay line register mfsyncpos_r. For example, when the imaging delay time is replaced with n scans + m lines (where n and m are integers), the register value “n” is stored in the sub-scan delay scan register mfdly_r, and the register value is stored in the sub-scan delay line register mfsyncpos_r. The value “m” is set.

  The MLSYNC generation unit 73 generates an image transfer request signal MLSYNC_N indicating an image transfer request and sends it to the image processing unit 342 and the delay line control unit 72.

  The delay line control unit 72 counts the number of generations of the image transfer request signal MLSYNC_N generated by the MLSYNC generation unit 73 within a main scanning period (scanning period) for simultaneously scanning (scanning) a plurality of lines in the main scanning direction, The MFSYNC generating unit 71 is notified of what number of image transfer request signals MLSYNC_N is output in the divided areas in each main scanning period.

  The delay scan control unit 75 includes delay timing control delay counters 0 to 3 (mfcount0 to 3), and controls the number of delay scans using these delay counters 0 to 3 (mfcount0 to 3). The delay scan control unit 75 loads the counter initial value at the timing of the write control unit operation start signal STOUT_N by the delay counters mfcount0 to 3 and down-counts the scan synchronization signal lcrl, and uses this count value in the sub-scanning direction. Control the number of delayed scans.

  More specifically, in the delay scan control unit 75, the delay counters mfcount0 to 3 selected by the write control unit operation start signal STOUT_N load the register value of the sub-scan delay scan register mfdly_r as an initial value. The delay scan control unit 75 decrements (counts down) the count value of the selected delay counters mfcount0 to 3 every time the scan synchronization signal lcrl is detected, and when the count value reaches 0, that is, When the number of occurrences of the scan synchronization signal lcrl becomes equal to the number of delayed sub-scans, the MFSYNC generator 71 is notified that the count value has reached zero.

  When the MFSYNC generating unit 71 for each color is notified from the delay scan control unit 75 that the delay counter has reached 0, it outputs the sub-scan start reference signal MFSYNC_N at different timings according to the determination result by the second determination unit. To do. Specifically, the MFSYNC generating unit 71 for each color receives the image transfer notified from the delay line control unit 72 when the timing at which the write control unit operation start signal STOUT_N is received is a 1/4 position of the main scanning period. The sub-scanning start reference signal MFSYNC_N is output to the image processing unit 342 at the timing when the request signal MLSYNC_N matches the number of information in the main scanning period and the sub-scanning delay line register mfsyncpos_r. Accordingly, the MFSYNC generating unit 71 for each color makes an image transfer request to the image processing unit 342 (see FIG. 7).

  On the other hand, the MFSYNC generating unit 71 for each color receives the image transfer request signal MLSYNC_N notified from the delay line control unit 72 when the timing at which the write control unit operation start signal STOUT_N is received is the 3/4 position of the main scanning period. Is a sub-scanning start reference signal that is a signal indicating a reference for starting printing in the sub-scanning direction to the image processing unit 342 at the timing when the number of information in the main scanning cycle matches the sub-scanning delay line register mfsyncpos_r + 4. MFSYNC_N is output. Accordingly, the MFSYNC generating unit 71 for each color makes an image transfer request to the image processing unit 342 (see FIG. 8).

  When the sub-scanning delay line register mfsyncpos_r + 4 exceeds the number of image transfer request signals MLSYNC_N output within one main scanning period, the MFSYNC generating unit 71 for each color performs the (sub-scanning) of the next main scanning period. Delay line register mfsyncpos_r + 4-8) The sub-scanning start reference signal MFSYNC_N is output at the timing when the image transfer request signal MLSYNC_N is output.

  The image processing unit 342 receives the input image data developed from the image acquisition unit 302 via the memory 340, performs various image processing based on the input image data, and performs image processing on the input image data. Has accumulated. Then, the image processing unit 342 uses the image data valid sub-gate signal IPFGATE and the accumulated image data based on the sub-scanning start reference signal MFSYNC_N input from the writing control units 70M, 70C, 70Y, and 70K for each color. The image signal IPDATA_N shown is output to the write controllers 70M, 70C, 70Y, and 70K. More specifically, the image processing unit 342 outputs the image data valid sub-gate signal IPFGATE and outputs the image signal IPDATA_N in units of lines according to the image transfer request signal MLSYNC_N after receiving the sub-scanning start reference signal MFSYNC_N. The number of lines to be simultaneously written (for example, 8 to 10 lines) is transferred.

  The write image expansion unit 76 in the write control units 70M, 70C, 70Y, and 70K converts the image signal IPDATA_N, which is a signal of image data, into a two-dimensional image signal for main scanning and sub-scanning based on the scan synchronization signal lcrl. This is expanded and supplied to the LD driver 312.

  The LD driver 312 drives the semiconductor laser element of the VCSEL 200 based on the input two-dimensional image signal. Thereby, a plurality of lines of image light are output in one scan.

  7 and 8 are explanatory diagrams illustrating timing charts of job start control of the image forming apparatus according to the present exemplary embodiment. 7 and 8, it is assumed that eight semiconductor laser elements are provided for each color, and eight lines are scanned in one scanning cycle (main scanning cycle), and an image transfer request to be output to the image processing unit 342 is assumed. Eight signals (line units) MLSYNC_N are generated within one scan cycle (main scan cycle).

A system operation start signal STTRIG_N is output from the engine control unit 330 to the writing control unit 70M at the detection timing of the transfer paper position by the registration sensor SS. Then, the reference color magenta color writing control unit 70M outputs the writing control unit operation start signal STOUT_N at a timing (specific timing described above) that does not generate the synchronization signal DETP_N and the scan synchronization signal lcrr for all colors (special timing). No. 2005-178080). In this embodiment, since images are formed in the order of magenta, cyan, yellow, and black, the register values of the sub-scan delay line registers mfdly_r for each color are set to the following relationship.
mfdly_r (M) <mfdly_r (C) <mfdly_r (Y) <mfdly_r (K)

  When the write control unit 70M outputs the write control unit operation start signal STOUT_N, the delay scan control unit 75 in the write control units 70M, 70C, 70Y, and 70K includes a plurality of delay counters mfcount0 to 3 for delay scan control. Select the delay counter to be operated. This counter selection is configured to be switched in the toggle order for each job transfer sheet. That is, when the delay counter mfcount0 is selected by receiving the first system operation start signal STTRIG_N, the delay counter mfcount1 is selected in the case of the next system operation start signal STTRIG_N. 7 and 8 show a case where the delay counter mfcount0 is selected.

  If the delay counter mfcount0 is selected as the delay counter when the write control unit operation start signal STOUT_N is generated, the count value of the delay counter mfcount0 is loaded with the register value of the sub-scan delay scan register mfdly_r as an initial value. In the example (p) of FIGS. 7 and 8, the number of delay scans “6” is set in the sub-scan delay scan register mfdly_r, and therefore “6” is loaded as an initial value in the delay counter mfcount0 (K). Shows the case. After loading the counter initial value, the delay counter mfcount0 is decremented for each surface of the polygon mirror 102a using the scan synchronization signal lcrl of the corresponding color as the counter clock.

  In the main scanning cycle when the counter value of the delay counter mfcount0 reaches 0, when the timing of the write control unit operation start signal STOUT_N is a 1/4 position of the main scanning cycle (FIG. 7), the MFSYNC generating unit 71 The sub-scanning start reference signal MFSYNC_N is output to the image processing unit 342 at the output timing of the number of image transfer request signals MLSYNC_N output in the main scanning period = mfsyncpos_r.

  On the other hand, in the main scanning period when the counter value of the delay counter mfcount0 has reached 0, when the timing of the write control unit operation start signal STOUT_N is at the 3/4 position of the main scanning period (FIG. 8), the MFSYNC generating unit 71 Outputs the sub-scanning start reference signal MFSYNC_N to the image processing unit 342 at the output timing of the number of image transfer request signals MLSYNC_N output in the main scanning cycle = mfsyncpos_r + 4.

  If the sub-scan delay line register mfsyncpos_r + 4 exceeds the number of image transfer request signals MLSYNC_N output within one main scan cycle, the (sub-scan delay line register mfsyncpos_r + 4-8) -th in the next main scan cycle The sub-scanning start reference signal MFSYNC_N is output at the timing when the image transfer request signal MLSYNC_N is output.

  In the present embodiment, the writing control unit 76 that develops the image signal IPDATA_N two-dimensionally on the transfer paper based on the system operation start signal STTRIG_N input at the asynchronous timing detected by the registration sensor SS. In order to form an image without disturbing the image writing position in the scanning direction, a writing control unit operation start signal STOUT_N is separately generated on the basis of the synchronization signal DETP_N, and the scan synchronization signal lcrl, which is the main scanning reference signal, starting from this timing. By controlling the number of delayed scans in the sub-scanning direction independently for each color, the color matching timing of each color in the sub-scanning direction can be controlled.

  In the present embodiment, the generation timing of the write control unit operation start signal STOUT_N is changed according to which position in the main scanning cycle the timing at which the system operation start signal STTRIG_N is received. When an image is output on paper, the shift amount of the image sub-scanning position with reference to the transfer paper edge between the transfer papers can be less than one scan.

  FIGS. 7Q to 7T show an example of the operation of the black delay scan control unit 75 in the portion AA circled in FIG. 7N. The delay scan control unit 75 is initially set in the delay counter mfcount0 (K) when the write control unit operation start signal STOUT_N is input from the magenta color write control unit 70M as the reference color to the black color write control unit 70K. The value mfdly_r (K) value is loaded. In FIG. 7, mfdly_r = 06h. The delay scan control unit 75 decrements the delay counter: mfcount0 (K) by 1 each time the black scan synchronization signal lcrl (K) is input. The MFSYNC generator 71 is a sub-scanning start reference signal MFSYNC_N (K) at the timing of the delay counter: mfcount0 (K) = 0h, the number of image transfer request signals MLSYNC_N output in that period = mfsyncpos_r. Is output. That is, the MFSYNC generator 71 sub-scanning start reference signal MFSYNC_N at the timing of the image transfer request signal MLSYNC_N = mfsyncpos_r in the region divided by the number of lines in the main scanning period in which a plurality of lines in the main scanning direction are scanned simultaneously. (K) is output.

  FIGS. 8Q to 8T show an example of the operation of the black delay scan control unit 75 in the portion BB circled in FIG. 8N. The delay scan control unit 75 is initially set in the delay counter mfcount0 (K) when the write control unit operation start signal STOUT_N is input from the magenta color write control unit 70M as the reference color to the black color write control unit 70K. The value mfdly_r (K) value is loaded. In FIG. 8, mfdly_r = 06h. The delay scan control unit 75 decrements the delay counter: mfcount0 (K) by 1 each time the black scan synchronization signal lcrl (K) is input. The MFSYNC generating unit 71 is a sub-scanning start reference signal MFSYNC_N (K) at the timing of the delay counter: mfcount0 (K) = 0h, the number of image transfer request signals MLSYNC_N output in that period = mfsyncpos_r + 4 Is output. That is, the MFSYNC generator 71 sub-scanning start reference signal MFSYNC_N at the timing of the number of image transfer request signal MLSYNC_N = mfsyncpos_r + 4 in the area divided by the number of lines in the main scanning period for simultaneously scanning a plurality of lines in the main scanning direction. (K) is output.

  After the sub-scanning start reference signal MFSYNC_N (K) is output, the delay counter mfcount0 (K) ends the decrement operation and shifts to the standby state FF00h. Sub-scan delay scan registers mfdly_r (M), mfdly_r (C), mfdly_r (Y), mfdly_r (K) and sub-scan delay line registers mfsyncpos_r (M), mfsyncpos_r (C), mfssyncY_pos (C), independently for each color Since mfsyncpos_r (K) is included, the sub-scan timing from the write control unit operation start signal STOUT_N to the output of the sub-scan start reference signal MFSYNC_N for each color can be arbitrarily set in units of lines by setting an appropriate value for each color. Adjustment is possible.

  As described above, in the present embodiment, the timing at which the system operation start signal STTRIG_N is received is determined as to which of the divided regions obtained by dividing the main scanning period into a plurality of times, and the timing at which the system operation start signal STTRIG_N is received. Accordingly, by changing the timing at which the sub-scanning start reference signal MFSYNC_N is output to the image processing unit 342, the sub-scanning position shift between a plurality of transfer sheets can be reduced to less than one scan unit.

DESCRIPTION OF SYMBOLS 15 Positioning pattern reading sensor 61 1st judgment part 62 2nd judgment part 70M, 70C, 70Y, 70K Write control part 71 MFSYNC generation part 72 Delay line control part 73 MLSYNC generation part 74 Synchronization signal control part 75 Delay scan control part 76 Written image developing section 100 Image forming apparatus 102 Optical apparatus 102a Polygon mirror 102b Reflecting mirror 102c Second cylindrical lens 104 Magenta color component image forming section 110 Black color component image forming sections 104a, 106a, 108a, 110a Photosensitive drum 104b, 106b, 108b, 110b Charger 104c, 106c, 108c, 110c Developer 106 Cyan component image forming unit 108 Yellow component image forming unit 112 Image forming unit 114 Intermediate transfer belt 114a, 114 , 114c conveying rollers 120 fixing device 122 the transfer unit 124 receiving member 134 paper feed registration roller 200 VCSEL
202 First Cylindrical Lens 204 Reflecting Mirror 206 Imaging Lens 208 Reflecting Mirror 210 Synchronization Detection Device 300 Control Unit 302 Image Acquisition Unit 304 VPU
306 IPU
308 Printer section 310 GAVD
312 LD driver 316 System bus 320 CPU
322 RAM
324 ROM
326 Image storage 328 Interface 330 Engine control unit 340 Memory 342 Image processing unit 344 Output data control unit 1001 Light source SS Registration sensor

JP 2005-178080 A

Claims (3)

An image processing unit that performs image processing of image data to be imaged;
A plurality of light sources that emit light beams by being driven and controlled,
A scanning unit that simultaneously scans a plurality of light beams corresponding to a plurality of lines in the main scanning direction;
An image forming unit that forms an electrostatic latent image of the image data of a plurality of lines in one scan on the image carrier by the plurality of light beams;
When a system operation start signal instructing the start of an image forming operation is received, a sub-scanning start reference signal indicating a reference for starting image formation in the sub-scanning direction is sent to the image processing unit, and the image processing unit A writing control unit that starts driving operation by driving the light source when data is received, and
A plurality of the write control units are provided corresponding to a plurality of colors including a reference color that is a reference color,
The writing control unit further determines in which divided region the divided region obtained by dividing the scanning cycle in the main scanning direction is the timing at which the system operation start signal is received. comprises a section, a front SL signal generation section for outputting a sub-scanning start reference signal to the image processing unit, a
The write control unit corresponding to the reference color instructs the start of a write operation at the same timing in a scanning cycle in the main scanning direction that is predetermined for each of the divided regions from which the system operation start signal is received. A sending section for sending a writing operation start signal to the writing control section for each color;
Each of the write control units further includes a second determination unit that determines in which of the divided regions the timing at which the write operation start signal is received is in the divided regions,
The signal generation unit sends the sub-scanning start reference signal to the image processing unit at a timing delayed by a time corresponding to a predetermined number of lines for each of the divided regions where the write operation start signal is received. Output,
The image processing apparatus further transfers the image data subjected to image processing to the writing control unit when the sub-scanning start reference signal is received. The first determination unit determines which of the divided regions of the divided regions obtained by dividing the scanning cycle in the main scanning direction into two divided regions by which the system operation start signal is received;
If the timing at which the system operation start signal is received is in the divided area in the first half of the scanning cycle in the main scanning direction, the sending unit sends the writing operation start signal to the predetermined part in the first half of the scanning cycle in the main scanning direction. And the writing operation start signal is sent to a predetermined position in the second half of the scanning cycle in the main scanning direction when the divided region is in the second half of the scanning cycle in the main scanning direction,
2. The image according to claim 1 , wherein the second determination unit determines whether the timing at which the write operation start signal is received is in the first half or the second half of a scanning cycle in the main scanning direction. Forming equipment. An image forming method executed by an image forming apparatus,
The image forming apparatus includes a plurality of light sources that emit a light beam by being driven and controlled, a scanning unit that simultaneously scans a plurality of light beams corresponding to a plurality of lines in a main scanning direction by the drive control of the light source, An image forming unit that forms an electrostatic latent image of a plurality of lines of image data in one scan on an image carrier with a plurality of light beams;
An image processing step in which an image processing unit performs image processing of the image data;
When a plurality of write controllers corresponding to each of a plurality of colors including a reference color, which is a reference color , receive a system operation start signal instructing the start of an image forming operation, Writing that starts a writing operation by driving the light source when a sub-scanning start reference signal indicating an image formation start reference is sent to the image processing unit and the image data is received from the image processing unit A control step,
In the writing control step, a first determination is made to determine in which divided area the divided period obtained by dividing the scanning cycle in the main scanning direction into a plurality of divided areas is the timing at which the system operation start signal is received. And the writing control unit corresponding to the reference color performs a writing operation at the same timing in a scanning cycle in the main scanning direction that is predetermined for each of the divided regions from which the system operation start signal is received. A sending step for sending a writing operation start signal for instructing the start to the writing control unit for each color, and the timing at which each of the writing control units receives the writing operation starting signal, a second determination step of determining whether the one of the divided regions, a time corresponding to the number of lines of the write operation start signal is predetermined for each of the divided regions received In only delayed timing, wherein the signal generation step of outputting the sub scanning start reference signal to the image processing unit,
The image processing method further includes transferring the image data subjected to the image processing to the writing control unit when the sub-scanning start reference signal is received.

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