JP2007088928A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing apparatus which performs correction including high-resolution skew, bow and error in the mounting position of a mechanism for achieving image formation while reducing memory capacity and suppressing apparatus expansion. <P>SOLUTION: For image data of 2,400 dpi, an image correction processor 54 controls an address of write to a correction line buffer memory 56 and stores those image data. The resolution of image data to be transmitted along an arrow 3A is 2,400 dpi and it is a data processing resolution resulting from processing (binarization processing due to dither error diffusion) in a data processing section 52. The resolution of image data to be transmitted along an arrow 3B, on the other hand, is 4,800 dpi that is double of 2,400 dpi; and it is a resolution for performing linearity correction upon image data. With the relevant resolution, correction is performed in a sub scan direction of image data and after the correction, in the relevant case, images of 4,800 dpi are output from an output section 60 for image formation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that forms a latent image by a plurality of main scans and sub-scans based on input image data, visualizes the latent image, and forms an image.

  The position correction by image processing can be performed more naturally and smoothly as the resolution is higher. When the resolution is lower, the jaggedness is noticeable and the image quality is deteriorated by performing the correction.

  In the tandem type image forming apparatus, cyan (C), magenta (M), yellow (Y), and black (K) recording units are arranged in order along the conveyance direction of the recording paper. When a color image is formed by superimposing and transferring a plurality of toners on a recording sheet, it is necessary to reduce misalignment in order to improve image quality.

  The positional deviation includes a positional deviation in the main scanning direction, a positional deviation in the sub-scanning direction, a skew (inclination) indicating a line inclination in the main scanning direction, and a bow (distortion). Regarding skew and bow correction, it is known to perform correction at a resolution higher than the data resolution.

  For example, an image forming apparatus is proposed in which LED elements are provided in synchronization with the 1 / n pixel pitch in the sub-scanning direction, and the resolution in the sub-scanning direction is increased by n times compared to the main scanning direction to improve the printing accuracy of position correction. (See Patent Document 1).

  However, when this technology is applied, there is a problem that the line buffer memory increases because it is stored in the memory after being divided into high resolutions.

  The misregistration correction by image processing has a problem of suppressing the cost increase while maintaining the image quality. In addition, in the LED array, it is difficult to increase the mounting position accuracy of the chip, so an error occurs and the position is shifted. Unlike the skew and bow, the positional deviation in this case does not have a linear inclination, and is a positional deviation in units of pixels or chips.

On the other hand, skew correction is performed by increasing the print resolution after correction with a low resolution line buffer amount. In order to perform skew correction by an image, a proposal has been made to increase the resolution and correct the skew by interpolation processing from a plurality of low resolution lines (see Patent Document 2).
JP-A-10-315545 JP 2000-278517 A

  However, although the technique of Patent Document 2 is a technique for the problem of reducing the buffer memory, it is intended for skew correction, and is not intended for correction of bow and LED chip mounting position errors. The contents described here can be corrected up to the number of lines (at low resolution) input at the same time, but in order to increase the correction amount, interpolation processing and correction line selection circuits become enormous. There is a problem that.

  In consideration of the above facts, the present invention is an image that performs correction including errors in the mounting position of a mechanism that realizes high-resolution skew, bow, and image formation while suppressing an increase in the size of the apparatus with a small amount of buffer memory. An object is to provide a processing apparatus.

  The present invention is an image forming apparatus that forms a latent image by a plurality of times of main scanning and sub-scanning based on input image data, visualizes the latent image, and forms an image in the main scanning direction. A positional deviation amount detecting means for detecting the positional deviation amount in the sub-scanning direction, and a correction parameter corresponding to the positional deviation amount detected by the positional deviation amount detecting means are set to n (the resolution of the input image data in the sub-scanning direction). n is a positive integer) correction parameter storage means for storing the resolution, correction line buffer memory for temporarily storing the input image data, and input image data stored in the correction line buffer memory. An address for controlling the address in the sub-scanning direction of the line for the input image data based on the correction parameter after interpolating the resolution in the sub-scanning direction by n times And having a control means.

  According to the present invention, when a latent image is formed by a plurality of times of main scanning and sub-scanning based on input image data, the latent image is visualized, and an image is formed, the positional deviation amount detection means includes: A positional deviation amount in the sub-scanning direction in the main scanning direction is detected, and a correction parameter storage means sets a correction parameter corresponding to the positional deviation amount detected by the positional deviation amount detection means in the sub-scanning direction of the input image data. The resolution is stored at a resolution n (n is a positive integer).

  Incidentally, the correction line buffer memory temporarily stores the input image data.

  Then, the address control means interpolates the resolution in the sub-scanning direction by the n times with respect to the input image data stored in the correction line buffer memory, and then sets the line for the input image data based on the correction parameter. Controls the address in the sub-scanning direction.

  That is, since the present invention does not interpolate the resolution of the output image, there is no need to increase the buffer memory amount. Once the input image data is stored in the correction line buffer memory, line correction in the sub-scanning direction can be performed with high resolution.

  In the present invention, it is determined whether or not the address control unit is to perform interpolation of resolution according to the resolution of interpolation performed by the address control unit, the resolution of the image to be formed, and the operation mode of image formation. The information processing apparatus further includes: a determination unit; and an implementation unit that causes the address control unit to perform resolution interpolation based on the determination of the determination unit.

  For example, even in the case of an image forming apparatus that supports color, in the case of performing monochrome output, it is often unnecessary to consider the influence of misregistration. There are also cases where it is desired to form an image at a data rate as low as possible.

  In the case described above, it is effective to determine whether or not the address control means performs resolution interpolation.

  Furthermore, in the present invention, the amount of positional deviation may be caused by at least one of skew and bow, or an LED array including LED chips that form the latent image is further provided. In addition to the skew and the bow, the LED chip may be mounted due to at least one of positional errors.

  That is, the linearity correction of all the positional deviations detected by the positional deviation detecting means, including the positional deviation due to skew, the positional deviation due to the bow, and the positional deviation of the mounting position error of the LED chip when the LED chip is mounted. Can be performed.

  In the present invention, the correction unit indicated by the correction parameter is an integral multiple of the number of pixels of the LED chip.

  Thereby, the correction unit of the correction parameter is set to an integer multiple of the number of pixels of the LED chip, so that correction can be performed without straddling the LED chips. The correction unit can be selected according to the correction / decomposition performance required for the image forming apparatus, such as a unit of several pixels or a unit of several tens of pixels.

  As described above, the present invention is an image that performs correction including errors in the mounting position of a mechanism that realizes high-resolution skew, bow, and image formation while suppressing an increase in the size of the apparatus with a small amount of buffer memory. It has an excellent effect of obtaining a processing apparatus.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating an environment in which an image forming apparatus 10 according to an embodiment of the present invention is used.

  As shown in FIG. 1, the image forming apparatus 10 according to the embodiment of the present invention is connected to a local network 11 including a client PC 11A and a network management PC 11B.

  The image forming apparatus 10 includes a document reading apparatus 12 that reads a document to be printed, a user interface (UI) 14 that inputs instructions from the user to the image forming apparatus 10 and reports information from the image forming apparatus 10 to the user. It has. Then, the manuscript reading device 12 starts reading by operating the UI 14.

  Further, the UI 14 can instruct the necessity of image data correction, the resolution of an image to be formed, and an operation mode such as monochrome or color.

  The image forming apparatus 10 performs color space conversion, gradation conversion, format conversion, and compression on input data (PDL) from the client PC 11 via the local network 11 and image data read by the document reading apparatus 12. An image processing controller 16 is provided that performs various processing such as image processing based on a print job or the like, and instructs execution of the printing processing.

  The image processing controller 16 is connected to an image formation processing unit (IOT) 18 that prints an image corresponding to the input image data on the recording paper P. The image processing controller 16 stores the image data in the page memory, and then transfers the image data in line units in synchronization with the page sync / line sync signal from the IOT 18. The IOT 18 performs image data processing such as tone density calibration unique to the apparatus, dither processing, and error diffusion processing.

  The image forming apparatus 10 according to the present embodiment has a configuration in which the image processing controller 16 and the IOT 18 are integrated, but the image processing controller 16 and the IOT 18 may be physically independent.

  FIG. 2A shows the internal configuration of the IOT 18. In the IOT 18, the photoreceptors 22Y, 22M, 22C, and 22K that rotate in the arrow A direction of each color of yellow (Y), magenta (M), cyan (C), and black (K) face the intermediate transfer belt 32 in parallel. Thus, a so-called tandem type full-color IOT is formed, in which toner images of four colors are superimposed while the intermediate transfer belt 32 makes one round. Note that when distinguishing each color of yellow, magenta, cyan, and black, Y, M, C, and K are added after the code. However, if there is no need to distinguish each color, Y, M, C, and K are omitted.

  A charging roll 24 that uniformly charges the surface of the photosensitive member 22 is in contact with the surface of the photosensitive member 22. Further, an LED array 26 for writing an electrostatic latent image on the surface of the photosensitive member 22 is disposed on the downstream side of the charging roller 24 in the rotation direction of the photosensitive member 22. Further, a developing device 28 for developing the electrostatic latent image into a toner image is in contact with the downstream side of the LED array 26.

  As shown in FIG. 2B, the LED array 26 has LED chips 27 arranged in a staggered manner in the main scanning direction with the arrangement direction aligned with the main scanning direction and the sub scanning direction positions alternately shifted. It consists of

  As a result of the staggered arrangement as described above, even if the pitch between the LED chips 27 is narrow for high resolution, an overlap is provided between the LED chips 27 adjacent to each other in the main scanning direction, and this overlap dimension is adjusted so that a predetermined value is obtained. It can be arranged in the main scanning direction at a pitch. Note that the LED chips 27 may be arranged in a line in the main scanning direction with the arrangement directions thereof aligned with the main scanning direction.

  The LED chips 27 in the entire LED array 26 are provided for the number of pixels corresponding to the resolution.

  By the way, in the case of the tandem type image forming apparatus 10 as in the present embodiment, it has a plurality of image forming apparatuses 20Y, 20M, 20C, and 20K and LED arrays 26Y, 26M, 26C, and 26K. When the toner image transferred to the intermediate transfer belt 32 is shifted, and when the image forming apparatuses 20Y, 20M, 20C, and 20K and the LED arrays 26Y, 26M, 26C, and 26K are configured to be detachable, There may be a positional shift for each color due to mounting variations due to replacement.

  The causes of color misregistration include variations due to mounting errors of individual LED chips 27 when the skew, bow, and LED array 26 as an apparatus due to mounting errors and component accuracy are used.

  Generally, the exposure point imaged by the LED chip 27 becomes a distorted image due to the mounting error of the LED chip 27 and the error of the imaging characteristics. The trajectory of the exposure point can be decomposed into a skew and a bow. When the locus of the exposure point becomes a skew, the lighting timing may be shifted in the sub-scanning direction according to the position in the main scanning direction. On the other hand, when it becomes a bow, the lighting timing may be shifted in line with the position in the main scanning direction in line symmetry with respect to the middle in the main scanning direction.

  In this way, it is possible to perform exposure as a continuous line by eliminating skew or bow.

  An intermediate transfer belt 32 is in contact with the developing device 28 on the downstream side in the rotation direction of the photosensitive member 22.

  The intermediate transfer belt 32 is wound around belt transport rollers 34A, 34B, 34C, and 34D so as to abut on the surface of the photoreceptor 22, and is rotated in the direction of arrow B. Primary transfer rolls 30 </ b> Y, 30 </ b> M, 30 </ b> C, and 30 </ b> K are disposed at a portion where the intermediate transfer belt 32 and the photosensitive member 22 are in contact with each other. The primary transfer roll 30 is used for the toner image formed on the photosensitive member 22. A voltage having a polarity opposite to the charging polarity is applied to the intermediate transfer belt 32, and the toner image is electrostatically attracted from the photosensitive member 22 to the intermediate transfer belt 32 to be primarily transferred.

  The IOT 18 includes a paper feed tray 36 at the bottom. The recording sheets P set in the sheet feeding tray 36 are fed one by one from the sheet feeding tray 36 to the downstream side in the conveying direction indicated by the arrow C, and are conveyed in accordance with the conveying timing of the recording sheet P. The image data is written to the LED arrays 26Y, 26M, 26C, and 26K and conveyed to the transfer unit 38.

  The transfer unit 38 is provided with a belt conveyance roll 34B around which the intermediate transfer belt 32 is wound, and a secondary transfer roll 38B pressed against the belt conveyance roll 34B. The secondary transfer roll 38B rotates in the arrow D direction. The intermediate transfer belt 32 is sandwiched between the nip portion of the belt conveyance roll 34B and the secondary transfer roll 38B, and the toner image is transferred from the intermediate transfer belt 32 when the recording paper P passes through the nip portion. It is like that.

  A fixing unit 40 is disposed downstream of the transfer unit 38 in the transport direction. The fixing unit 40 is provided with a heat roll 40A that reaches a high temperature and a backup roll 40B that is pressed against the heat roll 40A. The recording paper P has a nip portion between the heat roll 40A and the backup roll 40B. When passing, the toner is melted and solidified to be fixed on the recording paper P. The recording paper P is discharged to a discharge tray (not shown) by a discharge roll (not shown) arranged on the downstream side in the transport direction of the fixing unit 40.

  Also, during image formation, image misregistration (registration misalignment) may occur due to factors such as the writing position of each color image, variations in the position of the photoconductor, and changes in the speed of the transfer belt. Therefore, on the downstream side of the photosensitive member 22K and the upstream side of the transfer portion 38, the color registration of the toner images of the respective colors formed on the intermediate transfer belt 32 is detected, and the positional deviation amount detection for detecting the positional deviation amount. A color registration detection sensor 42 as means is provided.

  Next, the electrical system of the image forming apparatus 10 according to the present embodiment will be described with reference to FIG.

  As shown in FIG. 3, the image data read by the document reading device 12 is stored in a page memory 50 that is provided in the image processing controller 16 and is a storage memory for image data read by the document reading device 12. It is like that. The page memory 50 is controlled by the CPU 51.

  The image processing controller 16 is connected to the data processing unit 52. The data processing unit 52 performs conversion from a multi-value image to a binary image by dithering or error diffusion processing, and outputs the converted binary image to the image correction processing unit 54.

  Also, the image processing controller 16 determines whether or not to cause the image correction processing unit 54 to perform resolution interpolation depending on the resolution of the interpolation performed by the image correction processing unit 54, the resolution of the formed image, and the operation mode of image formation. It comes to judge.

  The image correction processing unit 54 receives image data at 2400 dpi from the data processing unit 52 such as dither or error diffusion processing. The image correction processing unit 54 controls the address for writing to the correction line buffer memory 56, and stores image data. The resolution of the image data transmitted by the arrow indicated by 3A is 2400 dpi.

  The image correction processing unit 54 is connected to a correction parameter storage unit 58 that stores a correction parameter indicating the amount of displacement. The line address is read from the correction line buffer memory 56, and address control is performed based on the value of the correction parameter stored in the correction parameter storage unit 58.

  The address readout control also serves as n times resolution conversion in the sub-scanning direction. The resolution of the image data transmitted by the arrow indicated by 3B is 4800 dpi, which is twice the resolution of 2400 dpi, for example. The resolution is a resolution for performing linearity correction on the image data. In this embodiment, the line in the main scanning direction of the image data is corrected based on the resolution, and after the correction, an image of 4800 dpi is output from the output unit 60 in the case.

  With respect to one write to the correction line buffer memory 56, 4800 dpi output can be realized by reading the same address twice.

  Thus, the read address control also doubles the resolution conversion in the sub-scanning direction. With respect to one write to the correction line buffer memory 56, an output of 4800 dpi can be realized by reading the same address twice.

  By the way, conventionally, for example, when the misregistration correction amount is 0.5 mm, a buffer memory for storing data of about 236 lines at 1200 dpi, about 472 lines at 2400 dpi, and about 944 lines at 4800 dpi is required.

  Therefore, in the case where the same misalignment correction is performed, if the sub-scanning is performed at a high resolution, the line buffer memory is greatly increased.

  However, in the present embodiment, for example, a 600 dpi multi-value image is converted into a 2400 dpi binary image by the data processing unit 52, and further an image correction process at 4800 dpi is performed in the sub-scanning direction for output. Yes.

  Thus, in this mechanism, since the data processing resolution is 2400 dpi, correction processing can be performed even if the capacity of the correction line buffer memory 56 is half of 4800 dpi. Thus, in this embodiment, image correction can be performed at a resolution of 4800 dpi without increasing the capacity of the correction line buffer memory 56, and image quality is not impaired.

  By the way, the correction control by the image correction processing unit 54 by the LED array 26 is output based on the detection result of the color registration detection sensor 42 or further based on the detection result of the mounting position error of each chip measured by the LED array 26 alone. This is performed via the unit 60.

  The LED array 26 is connected to and controlled by a machine control unit 62 that controls driving of the IOT 18. The machine control unit 62 controls the value of the correction parameter stored in the correction parameter storage unit 58 based on the signal received from the output unit 60 by the LED array 26.

  Further, the machine control unit 62 controls the timing generation unit 64, and the image processing controller 16 and the image correction processing unit 54 depend on the main scanning synchronization signal output from the timing generation unit 64, and the main scanning for the reading is performed. The synchronization signal is controlled by the output of the timing generator 64.

  It is well known that high resolution processing is advantageous for performing image correction processing. However, as described above, the output resolution (that is, the resolution for misalignment correction) and the data processing resolution (that is, the resolution for converting from a multi-value image to a binary image by dithering or error diffusion processing) are not necessarily the same. Need not be.

  In this embodiment, it is possible to detect the amount of misalignment regardless of the cause of misalignment and perform total linearity correction. Further, it is possible to provide an image forming apparatus with less color misregistration by performing image correction processing with a resolution higher than the data processing resolution without increasing the amount of buffer memory or enlarging the apparatus.

  In this embodiment, the data processing unit 52 provided in the IOT 18 performs dithering or error diffusion processing. However, the image processing controller 16 performs binarization, and a binary image is input to the IOT 18. Even if it is a mechanism, the basic concept is the same.

  Next, the operation of this embodiment will be described.

  First, the data processing unit 52 processes the input image data into 2400 dpi binary image data before image correction. The data is written in the image correction processing unit 54, address control of each line is performed, and the data is written in the correction line buffer memory 56. No correction parameter is added to the line address at the time of writing.

  Next, the address for each correction unit of the line read from the correction line buffer memory 56 is controlled by the correction parameter read from the correction parameter storage unit 58.

  The address for each correction unit of each line to which the correction parameter is added is output to the output unit 60, and the line is formed by the LED array 26.

  Here, the concept of linearity correction will be described with reference to FIG.

  A dotted line indicated by an arrow 4A in FIG. 4A indicates a correction unit in a certain main scanning direction.

  In FIG. 4, units separated by a dotted line indicated by the arrow 4A are referred to as a correction unit U1, a correction unit U2,..., A correction unit U21, and a correction unit U22 in order from the left in the drawing.

  A desirable state of a line formed by lighting the LED array 26 once is a state in which the line is straight along the main scanning direction, as indicated by an arrow 0L (2400), the 0th line at a resolution of 2400 dpi. It is.

  However, the line formed before the address correction has shifted in the sub-scanning direction as shown in FIG. 4B.

  As shown in FIG. 4C, the correction unit U1 is at the position indicated by the arrow A1, the correction unit U2 is at the position indicated by the arrow A2, the correction unit U4 is at the position indicated by the arrow A4, and so on. Correction is required.

  For example, when the deviation in the sub-scanning direction is a resolution unit of 2400 dpi as in the correction unit U2 and the correction unit U4, address control in the sub-scanning direction for one line of 2400 dpi may be performed.

  The dotted line indicated by the arrow 4B indicates the resolution of 4800 dpi in the sub-scanning direction. For example, as in the correction unit U1, the deviation in the sub-scanning direction is 1/2 of the resolution unit of 4800 dpi, that is, the resolution unit of 2400 dpi. It may be.

  Therefore, in the present embodiment, the address of each correction unit can be controlled with a resolution of 4800 dpi, which is twice the resolution of 2400 dpi.

  The cells indicated by arrows P1, P2, P3,..., P21, P22 shown in FIG. 4D indicate the concept of correction parameters for address control for each correction unit. The number corresponding to each correction unit indicates the number of lines to be moved at a resolution of 4800 dpi.

  The image correction processing unit 54 uses the value obtained by correcting the correction parameter value from the value of the main scanning synchronization signal counter of 4800 dpi as the read address of the processing target line, thereby correcting the line of the corrected image data of the processing target line. Are read from the correction line buffer memory 56. Even if the image data corrected during the processing becomes negative, there is no problem in outputting a white image.

  In the present embodiment, image data with a resolution of 2400 dpi is corrected with a resolution of 4800 dpi (that is, correction can be made with twice the fineness of the output image). For example, 7200 dpi, 9600 dpi, etc. Any configuration that performs correction at a resolution that is an integral multiple of the resolution of the output image processed by the data processing unit 52 may be used, and determination of the resolution related to the correction is arbitrary.

  On the other hand, even if the image forming apparatus 10 to be used is a color-compatible machine, the displacement of the image forming apparatus 20 and the LED array 26 may not be affected in the monochrome output operation mode. This is because there is no color misregistration in Y, M, C, and K (that is, color misregistration caused by overlapping a plurality of colors) in order to operate only the K image forming apparatus 20 and the LED array 26. It is.

  In addition, when the operation mode of monochrome output is operated at high speed, the data rate of image output becomes high. For this reason, there are cases where it is desired to output an image at a data rate as low as possible from the viewpoint of electromagnetic noise.

  For example, unlike the monochrome output, there is a case where there is no need to perform linearity correction including color misregistration and there is no need to output at a high resolution. In such a case, output is not performed at a high resolution such as 4800 dpi, and control is performed so that data processing of about 1200 dpi or 2400 dpi, that is, resolution conversion as in this embodiment is not performed. That is more effective.

  Based on the reasons described above, the presence or absence of the above-described function may be determined by setting the driver on the client PC 11 and the operation mode setting from the UI 14.

  When such a determination is made, the data processing unit 52 determines whether or not there is a function, and the image data from the data processing unit 52 is not processed by the image correction processing unit 54 but directly to the output unit 60. What is necessary is just to make it output.

  In addition, the main scanning correction unit of the correction parameter is set to an integral multiple of the number of lighting pixels in the LED chip 27, so that correction can be made without straddling the LED chip 27. The correction unit can be selected according to the correction / decomposition performance required for the image forming apparatus 10 such as a unit of several pixels or a unit of several tens of pixels. Note that it is preferable that the number of pixels in the main scanning direction and the number of pixels in the sub-scanning direction are not significantly different from each other.

  As described above, in this embodiment, it is possible to provide the image forming apparatus 10 with less color misregistration by performing image correction processing at a higher resolution than the data processing resolution and at a lower cost, performing total linearity correction.

  In this embodiment, the photosensitive member 22 is exposed using the LED array 26, but the exposure means is another exposure means such as a laser exposure device 66 as shown in FIG. Even it is effective. Needless to say, any mechanism capable of forming a latent image is not restricted by imagers such as the LED array 26 and the laser exposure device 66.

1 is an overall schematic diagram of a system including an image forming apparatus according to an embodiment. (A) is the schematic of IOT which concerns on this embodiment, (B) is explanatory drawing of a LED array. It is a block diagram of the principal part of the electric system which concerns on the image data processing which concerns on this embodiment. It is a conceptual diagram of linearity correction, (A) is an ideal main scanning line, (B) is a main scanning line before correction, (C) is a main scanning line after correction, and (D) is correction in the sub-scanning direction. Indicates a parameter. It is the schematic of IOT which used the laser exposure apparatus for the exposure means.

Explanation of symbols

10 Image forming apparatus 11 Local network 12 Document reading apparatus 14 UI
16 Image processing controller (determination means)
18 IOT
20 Image forming apparatus 22 Photoconductor 26 LED array 27 LED chip 42 Color registration detection sensor (position shift amount detection means)
50 page memory 51 CPU
52 Data processing unit 54 Image correction processing unit (address control means, implementation means)
56 correction line buffer memory 58 correction parameter storage (correction parameter storage means)
60 Output Unit 62 Machine Control Unit 64 Timing Generation Unit

Claims (5)

An image forming apparatus that forms a latent image by a plurality of times of main scanning and sub-scanning based on input image data, visualizes the latent image, and forms an image.
A positional deviation amount detecting means for detecting a positional deviation amount in the sub-scanning direction in the main scanning direction;
Correction parameter storage means for storing a correction parameter corresponding to the positional deviation amount detected by the positional deviation amount detection means at a resolution n (n is a positive integer) times the resolution of the input image data in the sub-scanning direction; ,
A correction line buffer memory for temporarily storing the input image data;
For the input image data stored in the correction line buffer memory, after interpolating the resolution in the sub-scanning direction by n times, the address of the line in the sub-scanning direction for the input image data is controlled based on the correction parameter Address control means to
An image forming apparatus comprising: A determination unit that determines whether or not to cause the address control unit to perform resolution interpolation according to a resolution of interpolation performed by the address control unit, a resolution of an image to be formed, and an operation mode of image formation;
Implementation means for causing the address control means to perform resolution interpolation based on the determination of the determination means;
The image forming apparatus according to claim 1, further comprising:   The image forming apparatus according to claim 1, wherein the amount of positional deviation is caused by at least one of skew and bow. An LED array composed of LED chips for forming the latent image;
3. The image forming apparatus according to claim 1, wherein the displacement amount is caused by at least one of skew, bow, and a position error of mounting the LED chip.   5. The image forming apparatus according to claim 4, wherein a correction unit indicated by the correction parameter is an integral multiple of the number of pixels of the LED chip.

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