JP2004271742A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form images in layers in an accurate position on an intermediate transfer body at a low cost regardless of positional accuracy of reference marks put on an intermediate transfer body. <P>SOLUTION: Toner images are formed in layers on the intermediate transfer body by using reference marks put on the intermediate transfer body. In this case, the timing of formation of each of the toner images in layers is set based upon a reference mark (one reference mark) detected first time from the time when image formation becomes ready. Then, a toner image formation process is started. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine and a printer, and more particularly to an electrophotographic image forming apparatus having an intermediate transfer member.
[0002]
[Prior art]
Conventionally, as an electrophotographic color image forming apparatus, an electrostatic latent image of each color is carried on a photoconductor, and a toner of a different color is applied to each electrostatic latent image and developed, and formed on the photoconductor. A color image forming apparatus has been realized in which the operation of primary transfer of a toner image to an intermediate transfer member is repeated for each color, and a full-color image formed on the intermediate transfer member is transferred to a transfer medium and fixed.
[0003]
In this type of color image forming apparatus, an image forming apparatus capable of forming a full-color image on a plurality of surfaces on an intermediate transfer member has also been realized.
[0004]
FIG. 8 shows a schematic configuration of an intermediate transfer body in an image forming apparatus capable of forming two full-color images on the intermediate transfer body.
[0005]
As shown in FIG. 8, on the intermediate transfer body 81, a first reference mark 82 indicating a reference position at a position facing the circumferential direction, a first reference mark sensor 83 for detecting the first reference mark 82, and a second reference mark sensor 83 are provided. A reference mark sensor 85 for detecting the reference mark 84 and the second reference mark 84 is provided.
[0006]
When the intermediate transfer body 81 is driven to rotate in the direction indicated by the arrow in the drawing, once each rotation of the intermediate transfer body 81, the first reference mark sensor 83 outputs the first reference mark 82 and the second reference mark sensor 85 outputs the second reference mark sensor 85. The reference mark 84 is detected.
[0007]
When a full-color image is formed under such a configuration, when the first fiducial mark sensor 83 detects the first fiducial mark 82 after the image can be formed, first, a yellow toner image on the first surface is formed. It is formed on a photoreceptor and transferred to the intermediate transfer member 81. Next, when the second fiducial mark sensor 85 detects the second fiducial mark 84, a yellow toner image on the second surface is formed on the photoconductor and transferred to the intermediate transfer body 81.
[0008]
Next, when the first fiducial mark sensor 83 detects the first fiducial mark 82, a magenta toner image on the first surface is formed on the photoconductor and transferred to the intermediate transfer body 81. Next, when the second fiducial mark sensor 85 detects the second fiducial mark 84, a magenta toner image on the second surface is formed on the photoconductor and transferred to the intermediate transfer body 81.
[0009]
Hereinafter, similarly, by repeating formation and transfer of cyan and black toner images, a full-color toner image in which the toner images of the first surface and the second surface are superimposed is transferred to the intermediate transfer body 81. You. Then, the full-color image on the intermediate transfer body 81 is transferred to the transfer medium and fixed, thereby completing the full-color image forming process. That is, the full-color image of the first surface is transferred to the area between the first reference mark 82 and the second reference mark 84 on the intermediate transfer body 81, and is transferred to the area between the second reference mark 84 and the first reference mark 82. The full-color image on the second surface is transferred.
[0010]
[Problems to be solved by the invention]
However, in the above-described method, if the circumferential positions of the first reference mark 82 and the second reference mark 84 are largely shifted, the full-color images of the first and second surfaces may overlap. .
[0011]
Further, when the peripheral length of the intermediate transfer body 81 is increased to increase the margin so that the full-color images on the first and second surfaces do not overlap, the size of the apparatus may be increased.
[0012]
Therefore, the first fiducial mark 82 and the second fiducial mark 84 need to be accurately provided at exactly opposite positions in the circumferential direction, which requires attention in manufacturing. Further, since the first reference mark 82 and the second reference mark 84 are detected by individual sensors, they are expensive.
[0013]
The present invention has been made under such a background, and an object thereof is to provide an inexpensive and accurate position on an intermediate transfer body regardless of the positional accuracy of a plurality of reference marks provided on the intermediate transfer body. In order to form an image on a plurality of surfaces.
[0014]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a rotatable photoconductor on which a toner image is formed, and the toner image on the photoconductor is primarily transferred, and the primary-transferred toner image is transferred onto a transfer material. A rotatable intermediate transfer body for secondary transfer, wherein a plurality of reference marks indicating circumferential positions on the intermediate transfer body are marked, and a reference mark on the intermediate transfer body is detected. An image forming apparatus capable of forming a toner image on a plurality of surfaces on the intermediate transfer body, based on a reference mark first detected by the detecting means from a time point when an image can be formed. Setting means for setting the timing for starting the formation of each toner image on a plurality of surfaces.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a diagram illustrating a schematic configuration of a full-color image forming apparatus to which the present invention is applied. The full-color image forming apparatus includes a color reader unit 1 and a color printer unit 2.
[0016]
First, the configuration of the color reader unit 1 will be described. Reference numeral 101 denotes a platen glass (platen), and reference numeral 102 denotes an automatic document feeder (ADF). Note that, instead of the automatic document feeder 102, a configuration may be employed in which a mirror surface pressure plate or a white pressure plate (not shown) is mounted.
[0017]
Reference numerals 103 and 104 denote light sources for illuminating the original, and light sources such as a halogen lamp, a fluorescent lamp, and a xenon tube lamp are used. Reference numerals 105 and 106 denote reflectors for condensing light from the light sources 103 and 104 onto the document. Reference numerals 107 to 109 denote mirrors for changing the traveling direction of reflected light or projection light (image light) from the original. Reference numeral 110 denotes a CCD (charge-coupled device) image sensor (hereinafter, referred to as CCD) 111 for transmitting image light from the mirrors 107 to 109. It is a lens that focuses light on the top.
[0018]
The CCD 111 is a color sensor. As a configuration for achieving this colorization, RGB color filters are placed in-line on a one-line CCD in the order of RGB, or in a three-line CCD, R filters, G filters, and B filters are arranged one-to-one on each line. Alternatively, a configuration in which a color filter is formed on a chip or is separated from a CCD may be used.
[0019]
Reference numeral 112 denotes a substrate on which the CCD 111 is mounted, 100 denotes an overall control unit for controlling the entire image forming apparatus, and 113 denotes a reader / scanner control unit, which has a digital image processing unit 113a described later. Reference numeral 114 denotes a carriage that houses the light sources 103 and 104, the reflectors 105 and 106, and the mirror 107. Reference numeral 115 denotes a carriage that houses the mirrors 108 and 109. Note that the carriage 114 is moved at a speed V and the carriage 115 is moved at a speed V / 2 mechanically in a sub-scanning direction Y orthogonal to the electrical scanning direction (main scanning direction X) of the CCD 111, thereby forming an original. Scan the entire surface.
[0020]
As shown in FIG. 2, the overall control unit 100 includes a CPU 301 having an I / F for exchanging information for controlling the digital image processing unit 113a and the printer control unit 250, an operation unit 303, and a memory. 302.
[0021]
The memory 302 includes a ROM (not shown) storing a control program for controlling the image forming apparatus, and a page memory 514 including a RAM for storing image data in page units. The operation unit 303 is configured by a liquid crystal with a touch panel, and is used for displaying an instruction input of processing contents, information on the instruction input, a warning, and the like.
[0022]
An external I / F 116 functions as an interface with an external device such as a facsimile device (not shown) or a LAN interface device (not shown). Note that control for exchanging image information and code information with an external device is performed by mutual communication between a control unit (not shown) of the external device and the CPU 301.
[0023]
Next, processing of the digital image processing unit 113a and the overall control unit 100 until image signal data is output to the printer control unit 250 will be described with reference to FIG. Note that reference numerals 502 to 513 shown in FIG. 3 are constituent elements of the digital image processing unit 113a.
[0024]
The original on the platen glass 101 reflects light from the light sources 103 and 104, and the reflected light (image light) is guided to the CCD 111 and converted into an electric signal. Then, the electric signal (analog image signal) is input to the digital image processing unit 113a, sampled and held (S / H processing) by the clamp & Amp & S / H & A / D unit 502, and the dark level of the analog image signal is set to the reference potential. The signal is clamped, amplified to a predetermined amount (the processing order is not limited to the display order), A / D converted, and converted into, for example, a digital image signal of 8 bits each for RGB.
[0025]
Then, the RGB digital image signal is subjected to shading correction and black correction by the shading unit 503, and then input to the connection & MTF correction & original detection unit 504. In the connection & MTF correction & document detection unit 504, when the CCD 111 is a three-line CCD, the reading position between the lines is different, so the delay amount for each line is adjusted according to the reading speed, and the reading positions of the three lines become the same. The connection processing is performed by correcting the signal timing as described above. Since the reading MTF changes depending on the reading speed and the magnification, the change is corrected (MIT correction processing), and the size of the document is recognized by scanning the document on the platen glass (document detection processing).
[0026]
The input masking unit 505 corrects the spectral characteristics of the CCD 111 and the spectral characteristics of the light sources 103 and 104 and the reflectors 105 and 106 of the digital image signal whose read position timing and the like have been corrected. The output of the input masking unit 505 is input to a selector 506 that can be switched with an external I / F signal. The image signal output from the selector 506 is input to the color space compression & background removal & LOG conversion unit 507 and the background removal unit 514.
[0027]
The signal input to the background removal unit 514 is input to a black character determination unit 515 that determines whether or not the document is a black character of the original document after the background is removed, and the black character determination unit 515 generates a black character signal. It is output to the moiré removing unit 509.
[0028]
On the other hand, the color space compression & background removal & LOG conversion unit 507 keeps the read image signal as it is if it is in a color space reproducible by the printer. The image signal is corrected so as to fall within the space (color space compression processing). Then, a background removal process is performed to convert the RGB signals into YMC signals (LOG conversion process).
[0029]
Then, the timing of the output signal of the color space compression & background removal & LOG conversion unit 507 is adjusted by the delay 508 in order to match the timing with the black character signal generated by the black character determination unit 515. The two types of signals are subjected to moiré removal by a moiré removal unit 509, subjected to scaling processing in the main scanning direction by a scaling unit 510, and input to the UCR & masking & black character reflection unit 511.
[0030]
In the UCR & masking & black character reflection unit 511, a YMCK signal is generated from the YMC signal (UCR processing), corrected by the masking processing unit to a signal suitable for the output of the printer (masking processing), and generated in the black character determination unit 515. The black character signal is fed back to the YMCK signal (black character reflection processing). The signal processed by the UCR & masking & black character reflection unit 511 is subjected to density adjustment by the γ correction unit 512 and then subjected to smoothing or edge processing by the filter unit 513.
[0031]
The digital image signal subjected to such a series of processing is temporarily stored in the page memory 514 on the overall control unit 100, and is synchronized with the video clock in accordance with the image writing reference timing signal of each color from the printer control unit 250. Are sequentially transmitted to the printer control unit 250 as image data signals.
[0032]
Next, the configuration of the color printer unit 2 will be described. In FIG. 1, a printer control unit 250 serves as a receiving port for a control signal from the CPU 301 on the overall control unit 100. The printer control unit 250 controls printing of the color printer unit 2 according to a control signal from the overall control unit 100, such as printing start.
[0033]
Reference numeral 201 denotes a laser scanner, which irradiates a photosensitive drum 202 by scanning a laser beam corresponding to an image data signal with a polygon mirror in a main scanning direction to form an electrostatic latent image. The electrostatic latent image formed on the photosensitive drum 202 reaches the one-color sleeve position in the four-color developing rotary 203 by rotating the photosensitive drum 202 clockwise. Then, an amount of toner corresponding to the potential difference between the surface potential of the photosensitive drum 202 on which the electrostatic latent image is formed and the developing sleeve surface to which the developing bias is applied is blown from each color developing device to the surface of the photosensitive drum 202. As a result, the electrostatic latent image on the surface of the photosensitive drum 202 is developed as a toner image.
[0034]
The toner image formed on the photosensitive drum 202 is primarily transferred to the intermediate transfer body 205 rotating counterclockwise by rotating the photosensitive drum 202 clockwise. Note that the intermediate transfer member 205 is configured by a belt member.
[0035]
In the case of a black monochrome image, the black toner image of each page is primarily transferred to the intermediate transfer body 205 at predetermined time intervals. In the case of a full-color image, the sleeve positions of the respective colors of the four-color developing rotary 203 are sequentially determined, and the electrostatic latent images corresponding to the respective colors on the photosensitive drum 202 are developed with toner. . After four rotations of the intermediate transfer member 205, that is, at the time when the four color toner images are stacked and primary transferred, the primary transfer of the full-color image is completed.
[0036]
On the other hand, each cassette (upper cassette 208, lower cassette 209, third cassette 210, and fourth cassette 211) is picked up by each of the pickup rollers 212, 213, 214, and 215 of each cassette, and supplied to each cassette. The recording paper transported by the paper rollers 216, 217, 218, and 219 is transported to the position of the registration roller 221 by the vertical path transport rollers 222, 223, 224, and 225. In the case of manual paper feed, the recording paper stacked on the manual feed tray 240 is transported to the position of the registration roller 221 by the manual paper feed roller 220.
[0037]
Then, the recording paper is conveyed between the intermediate transfer body 205 and the secondary transfer roller 206 at the timing when the primary transfer to the intermediate transfer body 205 is completed. The sheet is conveyed in the direction of the fixing device while being sandwiched between the intermediate transfer member 205. In the course of this conveyance, the recording paper is pressed against the intermediate transfer body 205, and the toner image on the intermediate transfer body 205 is secondarily transferred to the recording paper. The toner image transferred to the recording paper is heated and pressed by a fixing roller and a pressure roller 207 to be fixed on the recording paper.
[0038]
Regarding the transfer residual toner remaining on the intermediate transfer member 205 without being transferred to the recording paper, the intermediate transfer cleaning blade 230 that can be brought into contact with and separated from the surface of the intermediate transfer member 205 is rubbed. Scraped off the surface. Further, residual toner remaining on the photosensitive drum 202 is scraped off from the drum surface by the cleaning blade 231 and stored in the waste toner box 232. Further, the residual toner of each of the positive and negative polarities on the surface of the secondary transfer roller 206 which may be unexpectedly attracted is applied by alternately applying the secondary transfer positive bias and the secondary transfer reverse bias. After the residual toner of each polarity is once adsorbed on the intermediate transfer member 205, the residual toner is scraped off by the intermediate transfer cleaning blade 230.
[0039]
In the case of the first paper discharge, the recording paper on which the image has been fixed is switched to the first paper discharge flapper 237 in the direction of the first paper discharge roller 233, and is discharged toward the first paper discharge roller 233. . In the case of the second paper discharge, the first paper discharge flapper 237 and the second paper discharge flapper 238 are switched in the direction of the second paper discharge roller 234, and the paper is discharged toward the second paper discharge roller 234.
[0040]
In the case of the third discharge, the first discharge flapper and the second discharge flapper are switched in the direction of the reversing roller 235, conveyed to the position of the reversing roller 235, and reversed by the reversing roller 235. Then, after the sheet is reversed by the reversing roller 235, the third sheet discharging flapper 239 is switched to the third sheet discharging direction, and the sheet is discharged toward the third sheet discharging roller 236.
[0041]
In the case of the double-sided discharge, the reversing operation is once performed by the reversing roller 235 as in the case of the third discharge, and the third discharge flapper 239 is switched to the double-sided path 240 and conveyed to the double-sided path 240. . The conveyance is temporarily stopped after a predetermined time from the detection of the recording paper by the double-sided sensor, and as soon as the preparation for image formation on the back side is completed, the sheet is re-fed to the secondary transfer position via the registration roller 221 to form an image on the back side. Is done.
[0042]
The present full-color image forming apparatus can form two-sided images on the intermediate transfer body 205, and details thereof will be described below.
[0043]
FIG. 4 shows a configuration of the intermediate transfer member 205. Although the intermediate transfer body 205 is shown as being driven to rotate in a circular shape in FIG. 4, it is actually driven to rotate in a triangular shape as shown in FIG. Reference numeral 401 denotes a first reference mark indicating a first reference position (first home position: corresponding to HP1 in FIGS. 6 and 7) of the intermediate transfer member 205, and reference numeral 402 denotes a second reference position (second reference position) of the intermediate transfer member 205. Home position: corresponding to HP2 in FIGS. 6 and 7), reference numeral 403 denotes a reference mark sensor for detecting the first reference mark 401 and the second reference mark 402. In the figure, the reference mark sensor 403 detects the first reference mark 401 and the second reference mark 402 alternately by rotating the intermediate transfer member 205 in the direction of the arrow.
[0044]
FIG. 5 is a block diagram illustrating a schematic configuration of the printer control unit 250. In FIG. 5, reference numeral 601 denotes a CPU for controlling the printer control unit 250; 602, an ASIC (Application Specific Integrated Circuit) having functions for realizing main functions of the color printer unit 2; A ROM storing software, 604 is a work RAM for control software of the printer control unit 250, 605 is a communication interface (I / F) with the general control unit 100, and 606 is an I / O port.
[0045]
In this embodiment, when the reference mark sensor 403 detects the first reference mark 401 or the second reference mark 402 on the intermediate transfer member 205, an interrupt signal is input to the CPU 601.
[0046]
The ASIC 602 includes a detection signal of the first reference mark 401 or the second reference mark 402 and a count time T1 from the time of detection of the reference mark to writing of the image on the first surface, and a count from the detection time of the reference mark to writing of an image of the second surface. When the time T2 is instructed by the CPU 601, the respective counters for writing the images on the first and second surfaces are started with a predetermined reference clock. It has a function of outputting a write start timing signal and driving the laser scanner 201 based on an image data signal sequentially input from the overall control unit 100 in synchronization with a video clock in response to the output signal.
[0047]
Also, the ASIC 602 is instructed by the CPU 601 to permit / disallow the output of the image writing reference timing signal, and when the non-permission is instructed, the ASIC 602 outputs the image writing reference timing signal to the overall control unit 100 even if the designated count time is reached. It has a function to prevent output to
[0048]
In the present embodiment, a predetermined count time T1 until writing the image on the first surface and a count time T2 until writing the image on the second surface are set in the ASIC 602 from the CPU 601 before starting the image formation. I try to keep it.
[0049]
Next, a method of forming two full-color images on the intermediate transfer member 205 will be described with reference to FIG.
[0050]
From the time when image formation is instructed by the overall control unit 100 and an image can be formed (not shown), the first reference mark 401 or the second reference mark 402 is first detected by the reference mark sensor 403. (See FIG. 6A, hereinafter, it is assumed that the reference mark detected here is the first reference mark), the CPU 601 transmits the reference mark detection signal (see the HP detection signal in FIG. 6), The ASIC 602 sets permission to output the image writing reference timing signal for the first surface and the second surface.
[0051]
When the ASIC 602 has counted the count value T1 until the writing of the image on the first surface, the ASIC 602 outputs a reference timing signal for writing the image on the first surface to the overall control unit 100. As described above, the first surface yellow image is formed by the output of the first surface image writing reference timing signal, and the first surface yellow image is primarily transferred to the intermediate transfer body 205.
[0052]
Next, when the ASIC 602 counts the count value T2 until the writing of the image on the second surface, the ASIC 602 outputs a reference timing signal for writing the image on the second surface to the overall control unit 100. As described above, the second surface yellow image is formed by the output of the second surface image writing reference timing signal, and the second surface yellow image is primarily transferred to the intermediate transfer body 205.
[0053]
During this time, the reference mark sensor 403 detects the second reference mark 402 (see FIG. 6B), but in this detection, the CPU 601 does not set the reference mark detection signal to the ASIC 602.
[0054]
When the first reference mark 401 or the second reference mark 402 is first detected by the reference mark sensor 403 after the primary transfer of the yellow image on the second surface is completed (refer to FIG. The CPU 601 sets the ASIC 602 to permit the output of the reference mark detection signal (refer to the HP detection signal in FIG. 6) and the image writing reference timing signal of the first and second surfaces.
[0055]
When the ASIC 602 has counted the count value T1 until the writing of the image on the first surface, the ASIC 602 outputs a reference timing signal for writing the image on the first surface to the overall control unit 100. By the output of the image writing reference timing signal of the first surface, the magenta image of the first surface is formed, and the magenta image of the first surface is superimposed on the yellow image of the first surface on the intermediate transfer body 205. Transcribed.
[0056]
Next, when the ASIC 602 counts the count value T2 until the writing of the image on the second surface, the ASIC 602 outputs a reference timing signal for writing the image on the second surface to the overall control unit 100. By the output of the image writing reference timing signal of the second surface, magenta image formation of the second surface is performed, and the magenta image of the second surface is superimposed on the yellow image of the second surface on the intermediate transfer member 205 to form a primary image. Transcribed.
[0057]
During this time, the reference mark sensor 403 detects the second reference mark 402 (see D in FIG. 6), but in this detection, the CPU 601 does not set the reference mark detection signal to the ASIC 602.
[0058]
In the same manner, the cyan image and the black image on the first surface and the second surface are primary-transferred onto the intermediate transfer member 205 in a superimposed manner. Then, after the primary transfer of the black image on the second surface is completed, the CPU 601 sets the ASIC 602 to disable the output of the image writing reference timing signal, and the ASIC 602, as described above, The full-color images on the first and second surfaces are sequentially secondary-transferred to recording paper.
[0059]
As described above, since the image formation of each color and each surface is performed based on the same reference mark, regardless of the positional accuracy of the plurality of reference marks, without increasing the circumferential length of the intermediate transfer body. Thus, it is possible to form a full-color image having no color shift on each color and each surface on the intermediate transfer member.
[0060]
Therefore, it is not necessary to increase the size of the image forming apparatus in order to form images on a plurality of planes at accurate positions on the intermediate transfer body, and it is necessary to increase the precision of a manufacturing apparatus for marking fiducial marks on the intermediate transfer body. Nor.
[0061]
In addition, since a plurality of reference marks are employed and the image formation of each color and each surface is performed based on the first detected reference mark from the time when the image formation becomes possible, the image formation processing is quickly started. This makes it possible to improve the efficiency of the image forming process.
[0062]
Further, even if a plurality of fiducial marks are employed, only one fiducial mark sensor is required, so that the cost can be reduced.
[0063]
Next, with reference to FIG. 7, a description will be given of a process performed when some abnormality occurs in the apparatus in the process of forming two full-color images on the intermediate transfer body 205.
[0064]
After setting the reference mark detection signal and the permission to output the image writing reference timing signals on the first and second surfaces to the ASIC 602, the CPU 601 detects, for example, a case where there is no recording paper for secondary transfer of the second surface. If it is determined that the secondary transfer of the second side cannot be performed normally (see E in FIG. 7), such as when a paper feed failure occurs on the second side of the recording paper, the previous side (the first side in this example) At the timing of the end of the image formation, the ASIC 602 sets the non-permission of the image writing reference timing signal output of the second surface to the ASIC 602 (see F), and thereafter, prevents unnecessary image formation of the second surface.
[0065]
In this case, since the output of the image writing reference timing signal of the first surface is set to be permitted, the image formation of the first surface is continued.
[0066]
Further, for example, when it is determined that the secondary transfer cannot be performed normally on both the first and second surfaces, such as when a conveyance failure occurs in the recording paper that has been secondarily transferred before the first surface (see FIG. 7). H), and thereafter, the CPU 601 sets the ASIC 602 to disable image output reference timing signal output for both the first and second surfaces (see I in FIG. 7), thereby preventing unnecessary image formation. .
[0067]
Note that the present invention is not limited to the above-described embodiment, and can be variously applied and modified.
[0068]
For example, in the above-described embodiment, since the developing position does not change depending on each color, the count time T1 until writing the image on the first surface and the count time T2 until writing the image on the second surface are determined by the CPU 601 before starting image formation. However, when the image writing reference timing signal is changed for each color, such as when the developing position changes for each color, the first surface of the first surface is detected every time the reference mark on the intermediate transfer body 205 is detected. The count time until writing the image and the counting time until writing the image on the second surface may be set.
[0069]
Further, in the above embodiment, since it is assumed that the resolution of the formed image is not changed, a predetermined count time T1 until the writing of the image on the first surface and a count time T2 until the writing of the image on the second surface are determined. For example, in the case where the resolution is changed by changing the rotation speed of the photoconductor drum 202, one of the intermediate transfer members 205 is used based on the detection timing interval of a predetermined reference mark on the intermediate transfer member 205. It is also possible to measure the rotation time and correct the count time T1 until the image writing on the first surface and the count time T2 until the image writing on the second surface according to the one rotation time.
[0070]
Further, in the above embodiment, two reference marks are arranged on the intermediate transfer member 205. However, by arranging three or more reference marks, the image forming process can be started more quickly and the image forming process can be started. Can be made more efficient. In this case, since only one reference mark is used as a reference for image formation, the number of reference marks may be increased irrespective of the number of images formed on the intermediate transfer member.
[0071]
Further, in the above-described embodiment, the case where two images are formed on the intermediate transfer member is described as an example. However, the present invention can be applied to a case where more image surfaces are formed. In this case, it is necessary to set a count time for writing the image corresponding to the number of the image planes or the number of the image planes and the number of colors. Or a value obtained from the measurement result of one rotation time of the intermediate transfer member may be set.
[0072]
The present invention is applicable not only to the case where a plurality of color image surfaces are formed on an intermediate transfer member, but also to the case where a plurality of monochrome image surfaces are formed on an intermediate transfer member. Further, the above-described embodiments and applied modifications can be appropriately combined.
[0073]
Further, an object of the present invention is to supply a storage medium (or a recording medium) in which a program code of software for realizing the functions of the above-described embodiments and applied modifications is supplied to a system or an apparatus, and to provide a computer ( It is needless to say that the present invention can also be achieved by a CPU or an MPU) reading and executing a program code stored in a storage medium.
[0074]
In this case, the program code itself read out from the storage medium realizes the functions of the above-described embodiment and applied modifications, and the storage medium storing the program code constitutes the present invention. When the computer executes the readout program code, not only the functions of the above-described embodiments and the applied modifications are realized, but also the operating system running on the computer based on the instruction of the program code. It is needless to say that the OS or the like may perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments and applied modifications.
[0075]
Further, after the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. It goes without saying that the CPU or the like provided in the card or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments and applied modifications. When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the above-described embodiments and applied modifications.
[0076]
Hereinafter, the gist of the present invention will be summarized.
[0077]
Embodiment 1 A rotatable photoreceptor on which a toner image is formed, and a rotatable member on which the toner image on the photoreceptor is primary-transferred and the primary-transferred toner image is secondarily transferred to a transfer material. A flexible intermediate transfer body, comprising: an intermediate transfer body on which a plurality of reference marks indicating circumferential positions on the intermediate transfer body are written; and detection means for detecting the reference marks on the intermediate transfer body. An image forming apparatus capable of forming a toner image on a plurality of surfaces on the intermediate transfer body,
An image forming apparatus, comprising: a setting unit that sets a start timing of each toner image formation on a plurality of surfaces based on a reference mark first detected by the detection unit from a time point when an image can be formed.
[0078]
[Embodiment 2] In the case where a plurality of toner images of a monochrome image are formed on the intermediate transfer member, the setting unit is first detected by the detection unit from a point in time when an image can be formed. The image forming apparatus according to the first embodiment, wherein a start timing of forming each of the toner images on a plurality of surfaces of a black and white image is set based on a reference mark.
[0079]
[Embodiment 3] In the case where a plurality of surfaces of a color image are formed on the intermediate transfer member, the setting unit is first detected by the detection unit from a time point when an image can be formed. Based on the fiducial marks, a timing for starting the formation of each toner image on a plurality of surfaces for the first color forming the color image is set. Thereafter, each time the first fiducial mark detected is detected by the detecting means, The image forming apparatus according to the first embodiment, wherein the start timings of the formation of each toner image on a plurality of surfaces for another color forming an image are sequentially set.
[0080]
[Embodiment 4] discriminating means for discriminating, for each of the plurality of surfaces, whether or not the toner image primarily transferred on the intermediate transfer member can be normally and secondarily transferred onto a transfer material;
And invalidating means for invalidating the toner image formation start timing relating to the surface which has been normally determined by the determination means to be incapable of secondary transfer among the toner image formation start timings set by the setting means. The image forming apparatus according to any one of Embodiments 1 to 3, wherein
[0081]
Fifth Embodiment A rotatable photoconductor on which a toner image is formed, and a rotatable operation in which the toner image on the photoconductor is primarily transferred, and the primary-transferred toner image is secondarily transferred to a transfer material. A multi-layer toner image is formed on the intermediate transfer body using a flexible intermediate transfer body having a plurality of reference marks indicating circumferential positions on the intermediate transfer body. In the image forming method,
A detection step of detecting a reference mark on the intermediate transfer body,
An image forming method, comprising a setting step of setting a timing for starting formation of each toner image on a plurality of surfaces based on a reference mark first detected by the detection step from a time point when an image can be formed.
[0082]
【The invention's effect】
As described above, according to the present invention, regardless of the positional accuracy of a plurality of reference marks provided on an intermediate transfer member, a plurality of images are formed at accurate positions on the intermediate transfer member at low cost. It becomes possible.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus to which the present invention is applied.
FIG. 2 is a block diagram mainly showing a schematic configuration of an entire control unit of the image forming apparatus of FIG. 1;
FIG. 3 is a block diagram illustrating a configuration of a digital image processing unit.
FIG. 4 is a diagram showing a schematic configuration of an intermediate transfer member according to the embodiment of the present invention.
FIG. 5 is a block diagram illustrating a schematic configuration of a printer control unit according to the embodiment of the present invention.
FIG. 6 is a timing chart illustrating a process when forming a full-color image on two surfaces on an intermediate transfer member.
FIG. 7 is a timing chart illustrating processing when an abnormality occurs when two full-color images are formed on an intermediate transfer member.
FIG. 8 is a diagram showing a schematic configuration of a conventional intermediate transfer member.
[Explanation of symbols]
205: Intermediate transfer member
401: 1st fiducial mark
402: Second fiducial mark
403: Reference mark sensor
601: CPU
602: ASIC
603: ROM
604: RAM

Claims (1)

A rotatable photosensitive member on which a toner image is formed, and a rotatable intermediate transfer member for primary-transferring the toner image on the photosensitive member and secondary-transferring the primary-transferred toner image to a transfer material An intermediate transfer member on which a plurality of reference marks indicating circumferential positions on the intermediate transfer member are written, and a detection unit for detecting the reference mark on the intermediate transfer member, wherein the intermediate transfer member In an image forming apparatus capable of forming a plurality of toner images on a surface,
An image forming apparatus, comprising: a setting unit that sets a timing for starting formation of each toner image on a plurality of surfaces based on a reference mark first detected by the detection unit from a time point when an image can be formed.

Images