Image forming apparatus

Abstract

To provide an image forming device in which a setting value of printing on a plurality of toner colors for each page image is applied with a relatively simple configuration.SOLUTION: One write control part 43a of a plurality of write control parts 43a-43d transfers a setting value of each page from a first storage region 41a to its own second storage region 44a, and causes a corresponding print mechanism 10a to print a page image by applying the setting value stored in the second storage region 44a. The remaining write control parts 43b-43d transfer the setting values from the second storage regions 44a-44c of other write control parts 43a-43c to their own second storage regions 44b-44d, and cause corresponding print mechanisms 10b-10d to print the page image by applying the setting values stored in the second storage regions 44b-44d.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an image forming apparatus.

Background Art

[0002] Some image forming apparatuses include a plurality of printing mechanisms (such as a photosensitive drum, an exposure device, a developing device, etc.) corresponding to a plurality of toner colors (for example, cyan, magenta, yellow, black), and a writing control unit that controls the plurality of printing mechanisms to execute printing of the corresponding toner colors. Also, in some image forming apparatuses, such a writing control unit receives the set values of parameters for printing execution from a controller and stores them in a first storage means, and then transfers the set values to a second storage means one page at a time at a predetermined timing before printing a page image, and applies the set values to execute printing of the page image by the printing mechanism (see, for example, Patent Document 1).

[0003] On the other hand, some image forming apparatuses use a pseudo-random number sequence to determine the pixels (timings) for which the pixel width should be corrected in order to suppress the non-uniformity of the pixel width in the electrostatic latent image caused by the optical system of the exposure device, etc., and correct the pixel width of the pixels thus determined by adjusting the light emission time of the exposure device (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The image forming apparatus described above has a double buffer configuration with a first storage means and a second storage means. However, if multiple write control units corresponding to multiple toner colors operate independently, the controller that provides the above-mentioned setting values ​​to the multiple write control units must monitor the asynchronous print start timings of the page images of multiple toner colors and provide the above-mentioned setting values ​​to each of the multiple write control units in a timely manner before the print start timing. This complicates the processing of the controller and may delay the application of the above-mentioned setting values ​​and, consequently, the start of printing the page images.

[0006] This invention has been made in view of the above problems, and aims to provide an image forming apparatus that applies print setting values ​​for multiple toner colors for each page image with a relatively simple configuration. [Means for solving the problem]

[0007] The image forming apparatus according to the present invention comprises a plurality of printing mechanisms corresponding to a plurality of toner colors, a plurality of write control units that independently control each of the plurality of printing mechanisms to cause the plurality of printing mechanisms to perform printing of the plurality of toner colors, a first storage area, a controller that stores page-specific setting values ​​in the first storage area, and a plurality of second storage areas corresponding to each of the plurality of write control units. One of the plurality of write control units transfers the setting values ​​from the first storage area to its own second storage area, applies the setting values ​​stored in the second storage area to cause the corresponding printing mechanism to print the page image, and the remaining write control units transfer the setting values ​​from the second storage area of ​​the other write control units to their own second storage area, apply the setting values ​​stored in the second storage area to cause the corresponding printing mechanism to print the page image. [Effects of the Invention]

[0008] According to the present invention, an image forming apparatus can be obtained that applies print setting values ​​for multiple toner colors for each page image with a relatively simple configuration.

[0009] The above or other objects, features, and advantages of the present invention will become even more apparent from the following detailed description in conjunction with the accompanying drawings. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a side view showing a part of the mechanical internal configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 2] Figure 2 shows an example of a partial configuration of the exposure apparatus 2 in Figure 1 (configuration for one toner color). [Figure 3] Figure 3 is a block diagram showing a portion of the electrical configuration of the image forming apparatus shown in Figures 1 and 2. [Figure 4] Figure 4 is a timing chart illustrating the transfer of image data in the image forming apparatus according to Embodiment 1. [Figure 5] Figure 5 is a timing chart illustrating the transfer of set values ​​in the image forming apparatus according to Embodiment 1. [Figure 6] Figure 6 is a timing chart for when the resolution is changed between pages in the image forming apparatus according to Embodiment 1. [Figure 7] Figure 7 is a timing chart illustrating the transfer of set values ​​in the image forming apparatus according to Embodiment 3. [Figure 8] Figure 8 is a timing chart illustrating the transfer of set values ​​in the image forming apparatus according to Embodiment 4. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the figures.

[0012] Embodiment 1.

[0013] FIG. 1 is a side view showing a part of the mechanical internal configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus shown in FIG. 1 is a device having an electrophotographic printing function, such as a printer, a facsimile apparatus, a copying machine, a multifunction peripheral, and the like.

[0014] The image forming apparatus of this embodiment has a tandem type printing engine. This color developing device has photosensitive drums 1a to 1d corresponding to a plurality of toner colors, an exposure device 2, and developing devices 3a to 3d. The photosensitive drums 1a to 1d are photosensitive bodies of four colors: cyan, magenta, yellow, and black.

[0015] The exposure device 2 irradiates the photosensitive drums 1a to 1d while scanning a plurality of laser beams to form an electrostatic latent image corresponding to each color plane of a print image (page image) on the photosensitive drums 1a to 1d. The exposure device 2 has a laser diode that is a light source of the laser beam, and optical elements (lenses, mirrors, polygon mirrors, etc.) that guide the laser beam to the photosensitive drums 1a to 1d.

[0016] Furthermore, around the photosensitive drums 1a to 1d, a charger such as a scorotron, a cleaning device, a destaticizer, etc. are arranged. The cleaning device removes the residual toner on the photosensitive drums 1a to 1d after the primary transfer, and the destaticizer removes the static electricity of the photosensitive drums​​​​​​​The printing mechanism 10a including the photoreceptor drum 1a, the exposure device 2, and the developing device 3a performs development of a certain toner color (for example, black). The printing mechanism 10b including the photoreceptor drum 1b, the exposure device 2, and the developing device 3b performs development of another toner color (for example, magenta). The printing mechanism 10c including the photoreceptor drum 1c, the exposure device 2, and the developing device 3c performs development of another toner color (for example, cyan). The printing mechanism 10d including the photoreceptor drum 1d, the exposure device 2, and the developing device 3d performs development of another toner color (for example, yellow).

[0019] The intermediate transfer belt 4 is an annular image carrier that contacts the photoreceptor drums 1a to 1d and is primarily transferred with the toner images on the photoreceptor drums 1a to 1d. The intermediate transfer belt 4 is stretched over the driving roller 5 and circulates in the direction from the contact position with the photoreceptor drum 1d to the contact position with the photoreceptor drum 1a by the driving force from the driving roller 5.

[0020] The transfer roller 6 contacts the conveyed printing sheet with the intermediate transfer belt 4 and secondarily transfers the toner image on the intermediate transfer belt 4 to the printing sheet. The printing sheet onto which the toner image has been transferred is conveyed to the fixing device 9, and the toner image is fixed to the printing sheet.

[0021] The roller 7 has a cleaning brush, contacts the cleaning brush with the intermediate transfer belt 4, and removes the toner remaining on the intermediate transfer belt 4 after the transfer of the toner image to the printing sheet.

[0022] The sensor 8 is an optical sensor that measures the density of the developed toner image, irradiates the intermediate transfer belt 4 with a light beam, and detects the reflected light. For example, when adjusting the toner density, the sensor 8 irradiates a predetermined area of the intermediate transfer belt 4 with a light beam, detects the reflected light, and outputs an electrical signal corresponding to the amount of light.

[0023] FIG. 2 is a diagram showing an example of the partial configuration (configuration for one toner color) of the exposure device 2 in FIG. 1.

[0024] In Figure 2, the light-emitting element 21 is a light-emitting element such as a laser diode that generates the aforementioned laser beam. The optical system 22 is a group of various lenses arranged between the light-emitting element 21 and the polygon mirror 23, and / or between the polygon mirror 23 and the photoreceptor drum 1a and the BD sensor 24. An fθ lens is used in the optical system 22.

[0025] Furthermore, the polygon mirror 23 has an axis perpendicular to the axis of the photoreceptor drum 1a, and its cross-section perpendicular to that axis is polygonal, with its side surface acting as a mirror. The polygon mirror 23 rotates around its axis and scans the laser beam emitted from the light-emitting element 21 along the axial direction (main scanning direction) of the photoreceptor drum 1a, thereby scanning the laser beam. The motor 23a rotates the polygon mirror 23 according to control signals from the controller 41, etc., which will be described later.

[0026] Furthermore, the BD sensor 24 is an optical sensor that is installed at a predetermined detection position, detects the timing when the aforementioned laser beam scans that detection position, and outputs it as a BD signal. When a light beam enters the BD sensor 24, it induces an output voltage corresponding to the amount of light. The BD sensor 24 is placed at a predetermined position on the line through which the light beam is scanned, detects the timing when the light beam scans that predetermined position, and outputs the pulse formed at that timing as a BD signal.

[0027] The driver 31 includes a light source control circuit that controls the light-emitting element 21 to emit light and emit a laser beam, and a motor drive circuit that drives the motor 23a described above. This light source control circuit controls the emission of light from the light-emitting element 21 so that it is exposed by laser light in a pattern corresponding to the image to be formed in synchronization with the horizontal synchronization signal.

[0028] Figure 3 is a block diagram showing a part of the electrical configuration of the image forming apparatus shown in Figures 1 and 2. For example, as shown in Figure 3, the image forming apparatus further includes a controller 41, memory 42 such as RAM (Random Access Memory), and write control units 43a to 43d corresponding to multiple (in this case, four) toner colors.

[0029] The controller 41 is a computer that executes a predetermined program on a processor such as a CPU (Central Processing Unit). It receives print data supplied from a host device and performs predetermined image processing (color conversion, halftoning, etc.) on the print data, thereby generating image data for printing each toner color. The controller 41 also identifies the setting values ​​for print parameters according to print conditions and print sheet types specified by the user.

[0030] Memory 42 is a rewritable storage device in which a first storage area 41a is reserved, and second storage areas 44a to 44d corresponding to write control units 43a to 43d are reserved. Note that the first storage area 41a and the second storage areas 44a to 44d may be reserved in different memories.

[0031] The multiple write control units 43a to 43d are hardware parts that operate independently of each other, and they independently control the multiple print mechanisms 10a to 10d to perform printing with multiple toner colors (CMYK) on the multiple print mechanisms 10a to 10d.

[0032] Figure 4 is a timing chart illustrating the transfer of image data in the image forming apparatus according to Embodiment 1. The write control units 43a to 43d each generate vertical synchronization signals (Vsync1 to Vsync4) corresponding to pages and horizontal synchronization signals (Hsync1 to Hsync4) corresponding to lines based on the BD signal, and receive image data from the controller 41 during the assertion period of the image valid signal (MRE signal) in synchronization with the horizontal synchronization signals (Hsync1 to Hsync4).

[0033] Furthermore, the controller 41 stores page-specific settings for multiple page images to be printed in the first storage area 41a.

[0034] The write control unit 43a transfers the setting value from the first storage area 41a to its own second storage area 44a, and applies the setting value stored in the second storage area 44a to cause the corresponding print mechanism 10a to print the page image.

[0035] The remaining write control units 43b to 43d sequentially transfer their settings from the second storage areas 44a to 44c of the other (preceding) write control units 43a to 43c among the multiple write control units 43a to 43d to their own second storage areas 44b to 44d, and apply the settings stored in the second storage areas 44b to 44d to print the page image to the corresponding print mechanisms 10b to 10d, respectively.

[0036] In Embodiment 1, when printing multiple page images in succession, each of the multiple write control units 43a to 43d transfers the setting value for the next page image in synchronization with the BD signal during the negate period from the end of the assertion period of the vertical synchronization signals Vsync1 to Vsync4 corresponding to a certain page image among the multiple page images to the start of the assertion period of the vertical synchronization signals Vsync1 to Vsync4 corresponding to the next page image among the multiple page images.

[0037] Furthermore, the exposure apparatus 2 forces the light-emitting element 21 to emit light for a predetermined period when the scanning position of the laser beam reaches the detection position, and the multiple write control units 43a to 43d transfer the setting value for the next page image at the start timing of this forced emission. In this way, since the setting value for the next page image is transferred triggered by the start timing of this forced emission, the setting value for the next page image is reliably transferred before the start of printing of the next page image and reliably applied to the printing of the next page image. In other words, if the write control units 43a to 43d operate asynchronously with the controller 41 (writing the setting value to the first storage area 41a), and the setting value for the next page image is transferred after the detection of the BD signal, there is a possibility that the setting value for the next page image may not be reliably transferred before the start of printing of the next page image. However, by transferring the setting value for the next page image triggered by the start timing of the forced emission, it is reliably transferred before the start of printing of the next page image.

[0038] For example, the above setting value includes the number of horizontal synchronization signal pulses per cycle of the BD signal. For example, when switching the resolution in the main scanning direction, the number of horizontal synchronization signal pulses per cycle of the BD signal is changed. Also, for example, when the linear velocity is halved without changing the resolution, one horizontal synchronization signal pulse is generated every two cycles of the BD signal.

[0039] Next, the operation of the image forming apparatus according to Embodiment 1 will be described.

[0040] Figure 5 is a timing chart illustrating the transfer of setting values ​​in an image forming apparatus according to Embodiment 1. For example, as shown in Figure 5, after the setting value for the first page is stored in the first storage area 41a, the write control unit 43a, during the negate period of the vertical synchronization signal Vsync1 of the write control unit 43a, transfers the setting value for the first page from the first storage area 41a to its own second storage area 44a in synchronization with the BD signal (here, the start timing of the forced light emission period corresponding to the BD signal), and causes the print mechanism 10a to print the page image of the first page (the page image of the first toner color) according to the setting value for the first page.

[0041] After the setting value for the first page is transferred from the first storage area 41a to the second storage area 44a, the write control unit 43b, during the negate period of its vertical synchronization signal Vsync2, synchronizes with the BD signal (in this case, the start timing of the forced light emission period corresponding to the BD signal) to transfer the setting value for the first page from the second storage area 44a of the preceding write control unit 43a to its own second storage area 44b, and causes the print mechanism 10b to print the page image of the first page (the page image of the second toner color) according to the setting value for the first page.

[0042] Similarly, after the setting value for the first page is transferred from the second storage area 44a to the second storage area 44b, the write control unit 43c, during the negate period of the write control unit 43c's vertical synchronization signal Vsync3, synchronizes with the BD signal (in this case, the start timing of the forced light emission period corresponding to the BD signal) to transfer the setting value for the first page from the second storage area 44b of the preceding write control unit 43b to its own second storage area 44c, and causes the print mechanism 10c to print the page image of the first page (the page image of the third toner color) according to the setting value for the first page.

[0043] Similarly, after the setting value for the first page is transferred from the second storage area 44b to the second storage area 44c, the write control unit 43d, during the negate period of the write control unit 43d's vertical synchronization signal Vsync4, synchronizes with the BD signal (in this case, the start timing of the forced light emission period corresponding to the BD signal) and transfers the setting value for the first page from the second storage area 44c of the preceding write control unit 43c to its own second storage area 44d, causing the print mechanism 10d to print the page image of the first page (the page image of the fourth toner color) according to the setting value for the first page.

[0044] In this way, the settings are transferred in a cascaded manner to the second memory areas 44a to 44d through pipeline processing.

[0045] Then, the settings for each page from the second page onward are transferred in a similar pipeline process during the negate period following the vertical synchronization signals Vsync1 to Vsync4, from the preceding first storage area 41a or second storage areas 44a to 44c, and the page images are printed according to those settings.

[0046] Here, we will explain the case where the resolution changes between pages. Figure 6 is a timing chart for when the resolution changes between pages in the image forming apparatus according to Embodiment 1. The above-mentioned setting values ​​include the setting values ​​for the resolution of each page image (resolution in the main scanning direction), and when the setting values ​​(resolution in the main scanning direction) for the first and third pages are set to default values ​​and the setting value (resolution in the main scanning direction) for the second page is set to twice the default value, for example, as shown in Figure 6, the period of the horizontal synchronization signals Hsync1 to Hsync4 for the second page is set to half the period of the horizontal synchronization signals Hsync1 to Hsync4 for the first and third pages.

[0047] In this example, a single polygon mirror 23 scans the laser beam for all toner colors, generating a single BD signal. However, multiple polygon mirrors 23 may be used to scan the laser beam for multiple toner colors. In that case, a BD signal is generated for each toner color, and for each toner color, a vertical synchronization signal and a horizontal synchronization signal are generated according to that BD signal.

[0048] Furthermore, the above-mentioned settings may be common to all toner colors, or they may be different for each toner color. In that case, the settings for all toner colors may be transferred to the second storage area 44d of the final stage, or only the settings for the toner colors corresponding to the write control unit of itself and the subsequent stage may be transferred from the preceding stage, and only the settings for the toner colors corresponding to the write control unit of the subsequent stage may be transferred to the subsequent stage.

[0049] As described above, according to Embodiment 1, one of the multiple write control units 43a to 43d, write control unit 43a, transfers the setting value for each page from the first storage area 41a to its own second storage area 44a, and applies the setting value stored in the second storage area 44a to cause the corresponding print mechanism 10a to print the page image. The remaining write control units 43b to 43d transfer their setting values ​​from the second storage areas 44a to 44c of the other write control units 43a to 43c to their own second storage areas 44b to 44d, and apply the setting value stored in the second storage areas 44b to 44d to cause the corresponding print mechanisms 10b to 10d to print the page image.

[0050] This allows for a relatively simple configuration where print settings for multiple toner colors per page image are transferred at the appropriate time and applied to the printing of the page image.

[0051] Furthermore, even if there is a difference in the assertion period of the vertical synchronization signal for multiple toner colors, the setting values ​​are smoothly transferred to the second storage area 44a to 44d. In addition, even if the interval between print sheets (i.e., the negate period of the vertical synchronization signal) is short, and the first color of the next page is asserted before the fourth color of the previous page is asserted, the transfer of the setting value for the next page after the first color can be completed without the need for multi-stage FIFOs.

[0052] Embodiment 2.

[0053] In Embodiment 2, similar to the image forming apparatus described above (Japanese Patent Publication No. 2022-20979), the exposure apparatus 2 uses a pseudo-random number sequence to determine which pixels should have their pixel width corrected in order to suppress the non-uniformity of pixel width in the electrostatic latent image caused by the optical system of the exposure apparatus 2. The pixel width of the determined pixels is corrected by adjusting the light emission time of the light-emitting element 21. This pseudo-random number sequence is continuous from one line to the next drawn in the page image and is updated line by line.

[0054] Furthermore, in Embodiment 2, the light-emitting element 21 is a multi-beam element capable of generating multiple laser beams for each toner color page image, and the exposure apparatus 2 allows all of the multiple laser beams to light up in a certain line of the page image, and prohibits the lighting of some of the multiple laser beams in another line of the page image, and when the lighting of some of the multiple laser beams is prohibited, the updating of the pseudo-random number sequence is stopped for the prohibited portion, and the above setting value specifies whether or not to perform intermittent lighting of some laser beams for each page image, and by extension, specifies the line for which the updating of the pseudo-random number sequence is stopped.

[0055] The other configurations and operations of the image forming apparatus according to Embodiment 2 are the same as those of Embodiment 1, so their description will be omitted.

[0056] As described above, according to Embodiment 2, the continuity of the pseudo-random number sequence is appropriately maintained before and after the line where the laser beam is not lit.

[0057] Embodiment 3.

[0058] Figure 7 is a timing chart illustrating the transfer of set values ​​in the image forming apparatus according to Embodiment 3.

[0059] When printing multiple page images consecutively, for example as shown in Figure 7, each of the multiple write control units 43a to 43d transfers the setting values ​​for a particular page image from the preceding storage areas 41a, 44a to 44c at the start timing of the assertion period of the vertical synchronization signals Vsync1 to Vsync4 corresponding to that page image among the multiple page images (i.e., the rising edge timing).

[0060] The other configurations and operations of the image forming apparatus according to Embodiment 3 are the same as those of Embodiments 1 or 2, so their description will be omitted.

[0061] Embodiment 4.

[0062] Figure 8 is a timing chart illustrating the transfer of set values ​​in the image forming apparatus according to Embodiment 4.

[0063] When printing multiple page images consecutively, as shown in Figure 8, for example, each of the multiple write control units 43a to 43d transfers the setting values ​​for the next page image from the preceding storage areas 41a, 44a to 44c at the end of the assertion period (i.e., the falling edge) of the vertical synchronization signals Vsync1 to Vsync4 corresponding to a particular page image among the multiple page images. In Embodiment 4, the setting values ​​for the first page are transferred sequentially to the storage areas 41a, 44a to 44d as initial settings before the start of the assertion period of the vertical synchronization signal Vsync1 of the write control unit 43a corresponding to the first page.

[0064] The other configurations and operations of the image forming apparatus according to Embodiment 4 are the same as those of Embodiments 1 or 2, so their description will be omitted.

[0065] Various changes and modifications to the embodiments described above will be obvious to those skilled in the art. Such changes and modifications may be made without deviating from the spirit and scope of the subject matter and without diminishing the intended advantages. In other words, such changes and modifications are intended to be included in the claims. [Industrial applicability]

[0066] The present invention can be applied, for example, to an electrophotographic image forming apparatus. [Explanation of Symbols]

[0067] 1a~1d Photoconductor drum 2. Exposure apparatus 10a~10d Printing Mechanism 21 Light-emitting element 22 Optical system 24 BD sensor (an example of an optical sensor) 41 Controllers 41a 1st storage area 43a~43d Writing control unit 44a~44d 2nd storage area

Claims

1. Multiple printing mechanisms that support multiple toner colors, A plurality of writing control units that independently control each of the plurality of printing mechanisms to cause the plurality of printing mechanisms to execute prints of the plurality of toner colors, The first memory area and, A controller that stores page-specific settings in the first storage area, Each of the aforementioned write control units is provided with a plurality of second storage areas corresponding to it. One of the plurality of write control units transfers the setting value from the first storage area to its own second storage area, applies the setting value stored in the second storage area to print the page image to the corresponding print mechanism, The remaining write control unit among the plurality of write control units transfers the setting value from the second storage area of ​​the other write control unit among the plurality of write control units to its own second storage area, and applies the setting value stored in the second storage area to print the page image to the corresponding print mechanism. An image forming apparatus characterized by the following.

2. The aforementioned multiple printing mechanisms include multiple photoreceptor drums corresponding to the multiple toner colors, and an exposure device that scans multiple laser beams and irradiates the multiple photoreceptor drums with them. The exposure apparatus comprises a light-emitting element that generates the laser beam, and an optical sensor installed at a predetermined detection position that detects the timing at which the laser beam scans the detection position and outputs it as a BD signal. When printing multiple page images consecutively, each of the multiple write control units shall, during the negate period from the end of the assertion period of the vertical synchronization signal corresponding to one of the multiple page images to the start of the assertion period of the vertical synchronization signal corresponding to the next page image, transfer the setting value for the next page image in synchronization with the BD signal. The image forming apparatus according to claim 1, characterized by the following:

3. The exposure apparatus forces the light-emitting element to emit light for a predetermined period of time when the scanning position of the laser beam reaches the detection position. The plurality of write control units transfer the setting value for the next page image at the start timing of the forced light emission. The image forming apparatus according to claim 2, characterized by the following:

4. The image forming apparatus according to claim 2 or 3, characterized in that the setting value includes the number of pulses of the horizontal synchronization signal per period of the BD signal.

5. The exposure apparatus determines, using a pseudo-random number sequence, which pixels should have their pixel width corrected in order to suppress the non-uniformity of pixel width in the electrostatic latent image caused by the optical system of the exposure apparatus, and corrects the pixel width of the determined pixels by adjusting the light emission time of the light-emitting element. The aforementioned pseudo-random number sequence is continuous from one line to the next drawn in the page image, and is updated line by line. The light-emitting element is capable of generating multiple laser beams for the page image. The exposure apparatus allows all of the plurality of laser beams to light up in a certain line in the page image, and prohibits the lighting up of some of the plurality of laser beams in another line in the page image. When the lighting up of some of the plurality of laser beams is prohibited, the updating of the pseudo-random number sequence is stopped for the prohibited portion. The aforementioned setting specifies the line at which the updating of the pseudo-random number sequence is stopped. An image forming apparatus according to claim 2 or claim 3, characterized by the above.

6. The image forming apparatus according to claim 1, characterized in that when printing multiple page images in succession, each of the multiple write control units transfers the setting value for a page image at the start timing of the assertion period of the vertical synchronization signal corresponding to a page image among the multiple page images.

7. The image forming apparatus according to claim 1, characterized in that when printing multiple page images in succession, each of the multiple write control units transfers the setting value for the next page image at the end of the assertion period of the vertical synchronization signal corresponding to one of the multiple page images.

Images