JP2011031552A - Image forming apparatus, control method and program of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably record dots always with a fixed shape, size and density not based on surrounding input data and to stably perform a dot formation even if performing a recording at a short interval. <P>SOLUTION: When deciding the assignment of laser beams to record each of pixels of image after cut out and performing the recording using beams 202, 203, 204, 205, 206 and 207, a driving pulse generating period for respectively recording the pixel is decided by the formula; driving pulse generating period=distance between arrays/main scanning speed-distance between pixels/main scanning speed based on the driving pulse generating period of the beam 207 using the distance between arrays with the beam 207 and the distance between pixels with the pixel recorded by the beam 207 concerning the beams 202 to 206. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus including a plurality of recording elements arranged two-dimensionally, a control method thereof, and a program.

  In an electrophotographic image forming apparatus, generally, an image or an electrostatic latent image corresponding to an image signal is formed on a photosensitive drum or a photosensitive belt by a laser beam or the like, developed, transferred to a sheet, etc. Is forming.

  In an electrophotographic image forming apparatus, in addition to binary recording in which an image is formed by applying or not applying a laser beam, gradation can be expressed in one pixel by changing the area of one dot. A method for improving the high resolution and gradation is used. For example, there are a PWM method (Patent Document 1) that modulates the width of a laser drive pulse in accordance with the density of an input image, and a method that changes the spot shape of a laser beam using a movable slit (Patent Document 2).

  In recent years, in an electrophotographic image forming apparatus, an image recording method using a plurality of laser beams at the same time has been demanded in order to achieve high resolution and high speed. An edge-emitting semiconductor laser (LD: Laser Diode) that has been conventionally used as a light source of an optical scanning device is difficult to integrate, and there are only about four beams that can be scanned and exposed simultaneously. However, by using a surface emitting semiconductor laser (VCSEL: Vertical Cavity Surface Emitting Diode Laser) in which a plurality of light emitting points are two-dimensionally arranged as a light source of an optical scanning device, it is possible to simultaneously scan and expose a photoconductor with a plurality of beams. (Patent Document 3).

Japanese Patent Laid-Open No. 7-184051 JP-A-5-019206 JP 2003-182149 A

  In an electrophotographic image forming apparatus, the relationship between a laser driving pulse width and a laser emission amount is generally not linear. Therefore, as shown in FIG. 13, a light emission amount 1402 when exposed using a plurality of isolated pulses 1401 and a light emission amount 1404 when exposed using a pulse 1403 having a width equal to the sum of the isolated pulses, A difference occurs in the total laser light quantity. This difference in the total laser emission amount appears as a difference in the amount of toner formed on the medium, that is, a difference in density. Therefore, there is a problem that even if the input data is the same, the output density varies depending on the surrounding data. As in Patent Documents 1, 2, and 3, when one main scanning line is main-scanned with one beam, density unevenness occurs due to the nonlinearity of the above-described input data and output density.

  In the PWM method described in Patent Document 1, it is necessary to control the laser drive pulse at a frequency higher than the interval of one dot. As shown in FIG. 14, when an isolated pulse is generated at a short time interval as in 1501, the laser emission cannot catch up when the laser driving pulse becomes a high frequency due to the problem of laser light emission responsiveness. 1502 becomes unstable. Therefore, it is necessary to control the position and shape of the center of gravity of PWM so that peripheral pixels can be continuously exposed, and there is a problem that the degree of freedom of the shape of PWM is reduced.

  Similarly, in the method of physically changing the laser beam shape using the slit described in Patent Document 2, density unevenness occurs in isolated exposure and continuous exposure. Moreover, since the laser beam shape depends on the slit shape, there is a problem that the degree of freedom of the shape is low.

  The present invention has been made to solve such a problem, and can always stably record dots with a constant shape, size and density regardless of surrounding input data, and can record at short intervals. It is an object of the present invention to enable dot formation stably even if the recording is performed and to record in an arbitrary halftone dot shape.

An image forming apparatus according to the present invention includes a recording unit having a two-dimensional recording element arrangement in which a plurality of recording elements are arranged on the same main scanning line, and a plurality of recording elements for each pixel of a recording target image. A recording element determination unit that determines which recording element to use for recording, and among the recording elements that perform the recording, the drive timing of the other recording elements is determined based on the drive timing of a predetermined recording element, Using the distance between the main scanning direction with a predetermined recording element and the inter-pixel distance with the pixel to be recorded,
Drive timing determining means for driving timing = distance between main scanning directions / main scanning speed−distance between pixels / main scanning speed is provided.

  According to the present invention, dots can always be stably recorded with a constant shape, size, and density regardless of surrounding input data, and dots can be stably formed even when recording is performed at short intervals. can do.

1 is a block diagram illustrating a configuration of an image forming apparatus according to a first embodiment. It is a figure which shows the structural example of the laser oscillator in 1st Embodiment. It is a figure which shows the laser oscillator structure equivalent to the structure of the laser transmitter in 1st Embodiment. 3 is a flowchart illustrating image forming processing in the first embodiment. It is a figure which shows the detail of the color separation process in 1st Embodiment. It is a figure which shows the example of the binary pattern replacement process in 1st Embodiment. It is a figure which shows the example of the recording beam determination process of each pixel in 1st Embodiment. It is a figure which shows the example of a laser drive in 1st Embodiment. It is a figure which shows the example of a laser drive in 1st Embodiment. It is a figure which shows the example of the block allocation table in 2nd Embodiment. It is a figure which shows the example of a drive of the laser in 2nd Embodiment. It is a figure which shows the example of a drive of the laser in 2nd Embodiment. FIG. 4 is a diagram for explaining a problem of an electrophotographic image forming apparatus. It is a diagram illustrating a problem of an electrophotographic image forming apparatus.

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
<First Embodiment>
In this embodiment, an electrophotographic image forming apparatus will be described as an example. However, the application of the present invention is not limited to an electrophotographic image forming apparatus. For example, the present invention can be applied to a recording apparatus having a plurality of recording elements (nozzles in the case of an inkjet system) for each color ink, such as an inkjet image forming apparatus.

  FIG. 1 is a block diagram illustrating a configuration of the image forming apparatus according to the first embodiment. The image forming apparatus includes a photosensitive drum 101 on a drum as an image carrier, a charging unit 102 for forming an electrostatic latent image, an exposure unit 103, and a developing unit 104 for converting the electrostatic latent image into a visible image. Prepare. Further, the image forming apparatus includes a transfer unit 105 for transferring an image developed by the developing unit 104 to a transfer material S that is a recording medium, and a fixing unit 107 for fixing the transfer material S that has been subjected to transfer processing by heating and pressing. .

  The photosensitive drum 101 is composed of a photosensitive layer made of OPC (organic semiconductor) or the like on the outer peripheral surface of a metal drum base, and is driven to rotate by a drive unit (not shown). Around the photosensitive drum 101, a charging unit 102, an exposure unit 103, a developing unit 104, a transfer unit 105, a cleaning unit 106, and the like are provided.

  The charging unit 102 includes a charging roller (not shown) disposed in contact with the surface of the photosensitive drum 101 and a charging bias electric wire that applies a charging bias to the charging roller, and uniformly charges the surface of the photosensitive drum 101. To do.

  The exposure unit 103 includes a laser oscillator 108, a polygon mirror 109, an Fθ lens 110, and the like. The exposure unit 103 irradiates the surface of the photosensitive drum 101 with a plurality of laser beams (multi-beams) emitted from the laser oscillator 108 based on the input image data, and forms an electrostatic latent image on the surface of the photosensitive drum 101.

  FIG. 2 shows a configuration example of the laser oscillator 108 used in the present embodiment. It is assumed that the laser oscillator 108 includes a total of 64 laser beam irradiation ports (also referred to as beams) 201 in which 16 multi-beam arrays arranged in the sub-scanning direction are arranged in 16 rows in a staggered manner. In the above configuration, the array No. No. 1 after the main scan has moved 20 μm (when the main scan speed is 1 m / s, 20 μs has passed) By driving 0, array no. 1 and array no. 0 can record on one straight line in the sub-scanning direction. Array No. Since the same can be said between adjacent arrays such as 2, 3, etc., the configuration of FIG. 2 can be regarded as equivalent to the configuration of FIG. 3 by adjusting the drive timing of each array. Here, it is assumed that each laser beam irradiation port 201 can irradiate a laser beam simultaneously and independently.

  Note that the configuration of the laser oscillator 108 is not limited to the above configuration, and is a two-dimensional recording element arrangement in which a plurality of recording elements are arranged on the same main scanning line as shown in FIGS. I just need it.

Further, the following relational expression number of recording elements in the main scanning direction × pixel distance in the main scanning direction / main scanning speed
> The time interval necessary for stable driving of the recording element is satisfied. That is, when one laser beam irradiation port is driven by a plurality of isolated pulses, the time interval between isolated pulses, the dot recording interval (dot pitch) in the main scanning direction, the number of arrays, and the main scanning speed capable of stably emitting laser light Therefore, it is necessary to determine the dot pitch in the main scanning direction, the number of arrays, and the main scanning speed so that the following four satisfy the following relationship.
Number of arrays x main scanning direction dot pitch / main scanning speed
> Isolated pulse time interval capable of stable laser emission (1)

  Hereinafter, the number of beams arranged in the main scanning direction in FIG. 3 is referred to as the number of arrays, and the number of beams arranged in the sub-scanning direction is referred to as the number of beams in the array. Further, as the coordinates of the two-dimensional arrangement, the array No. is taken in the main scanning direction and the beam No. is taken in the sub scanning direction, and the position of the laser beam is expressed by this combination.

  The developing unit 104 includes a developing unit that stores developers (toners) of four colors of yellow (Y), magenta (M), cyan (C), and black (K). Each toner is attached to the image and developed as a toner image.

  The transfer unit 105 includes an intermediate transfer drum 111 that is an image carrier formed in a cylindrical shape, and primarily transfers the toner image on the photosensitive drum 101 onto the intermediate transfer drum 111.

  The cleaning unit 106 has a cleaning blade disposed in contact with the surface of the photosensitive drum 101, and removes primary transfer residual toner remaining on the photosensitive drum 101 without being primarily transferred to the intermediate transfer drum.

  A secondary transfer belt 112 is provided below the intermediate transfer drum 111, and the four-color toner images primarily transferred onto the intermediate transfer drum 111 are secondarily transferred onto the transfer material S all at once. The transfer material S after the secondary transfer of the toner image is heated and pressurized by the fixing unit 107, and the toner image is fixed on the transfer material S.

  Next, the operation of the image forming apparatus of the present embodiment having the above-described functional configuration will be described with reference to the flowchart of FIG. The flowchart in FIG. 4 is realized, for example, when a CPU in the image forming apparatus executes a control program.

  First, multi-tone color input image data is input (step S101). Here, as the input image data, color image data is constructed by three color components of red (R), green (G), and blue (B).

  Next, color separation processing from RGB to CMYK toner color planes is performed on the multi-tone color input image data using the color separation LUT (step S102). In this embodiment, each pixel data after color separation processing is handled as 8 bits, but conversion to a higher number of gradations may be performed. As described above, the developing unit 104 in the present embodiment has four types of toner colors. Therefore, 4-plane image data corresponding to each color of CMYK is generated from RGB color input image data.

Here, details of the color separation processing in the present embodiment will be described with reference to FIG. FIG. 5 shows details of input / output data in the color separation processing unit 103. As shown in the figure, the input image data RGB is converted into CMYK data as shown in the following equation with reference to the color separation LUT.
C = C_LUT — 3D (R, G, B) (2)
K = M_LUT — 3D (R, G, B) (3)
Y = Y_LUT — 3D (R, G, B) (4)
K = K_LUT — 3D (R, G, B) (5)

  Here, each function defined on the right side of the expression corresponds to the contents of the color separation LUT. The color separation LUT determines an output value for each toner color from three input values of R, G, and B. In the present embodiment, since the configuration includes four colors of CMYK, an LUT configuration that obtains four output values from three input values is obtained. With the above processing, the color separation processing in this embodiment is completed.

  Returning to the flowchart of the embodiment of FIG. 4, next, halftone processing is performed on each image corresponding to each toner color (step S103). The subsequent processing is performed on an image corresponding to each toner color, but only the processing for one toner color is described for the sake of simplicity. The halftone process converts each pixel of the color-separated image into M gradation data (2 <M <number of gradations after color separation). As the halftone processing method, for example, any halftone processing method such as a dither method using a threshold matrix, an FM screen processing method, or an error diffusion method may be used.

  Subsequently, a binary pattern replacement process is performed (step S104). The binary pattern replacement process is a process of replacing each pixel of the M-valued image in step S103 with a binary pattern composed of a plurality of pixels having a resolution smaller than that of the M-valued image corresponding to each level of 0 to M. is there. The binary pattern corresponding to each level may be any pattern that can be expressed as a two-dimensional pattern, may be generated for each process by a random number, or a predetermined pattern is prepared. May be. At this time, the number of patterns prepared in advance is not limited to one for each level. A plurality of patterns may be prepared and one pattern may be selected for each process.

  FIG. 6 shows an example of processing for replacing a quinary image with a binary pattern. FIG. 6A shows a binary pattern corresponding to each of levels 0-4. In this example, one 2 × 2 pixel pattern is prepared for each level. FIG. 6C shows the result of replacing the quinary image in FIG. 6B with the binary pattern in FIG. This process is a process corresponding to a PWM process for expressing a gradation in one pixel.

Next, an image to be recorded in each main scan is cut out (step S105). In the present embodiment, since the number of beams in the sub-scanning direction is 8, only 8 lines of images can be recorded in one main scan. Therefore, for each main scan, an image to be recorded in the main scan is cut out. When the scan number is N (0 ≦ N) and the coordinates of the upper left pixel of the image to be recorded in the main scan are the cutout start position, the cutout start position Ycut can be expressed by the following expression.
Ycut = Y0 + LF × N (6)

Here, the feed amount in the sub-scanning direction performed between successive main scans is LF, and the cut-out start position when the scan number is 0 is Y0. Then, lines corresponding to the number of beams in the array (8 in the example) are cut out from the cut-out start position set by the above formula. The image cut-out process can be expressed by the following formula, where the binarized result image is IMG (X, Y) and the cut-out image is IMGcut (X, Y).
IMGcut (X, Y) = IMG (X, Ycut + Y) (7)
0 ≦ X <(number of pixels in the main scanning direction of the binary image)
0 ≦ Y <(Number of beams in the array)

  Subsequently, a recording element determination process is performed to determine which laser beam is used to record each pixel of the clipped image that is the recording target image (step S106). The beam No, which is the beam coordinate in the sub-scanning direction used for recording, is determined according to the sub-scanning coordinate in the cut-out image. That is, the beam No. equal to the sub-scanning direction coordinates of each pixel in the cut-out image is used. Next, an array number which is a beam coordinate in the main scanning direction is determined. First, each line in the main scanning direction of the cut-out image is divided into blocks each composed of pixels of the number of arrays. Then, which array is used for recording is assigned to each pixel in the block. At this time, the allocation is performed so that all the arrays are used once without duplication. In addition, although the array assignment may be changed for each block, it is preferable that the array assignments in the blocks arranged in the main scanning direction are equal and each array is periodically assigned on the line in the main scanning direction. For example, the in-block main scanning direction coordinate of the pixel at the left end of the block is set to 0, and the in-block main scanning direction coordinate of the pixel at the right end of the block is set to (number of arrays-1). . The above allocation method is shown in FIG. In FIG. 7, the numbers assigned to the pixels of the cut-out image represent the in-block coordinates, and at the same time, the array number for recording the pixels.

  Thus, the assignment of which laser beam is used to record each pixel of the post-cut image is determined.

  Subsequently, the generation timing of the driving pulse is adjusted (driving timing determination), an electrostatic latent image is formed on the photosensitive drum 101, and development, transfer onto a sheet, and fixing recording processing are performed (step S107). Here, as an example of the generation timing of the drive pulse, a case where the binary image shown in FIG. 8A is recorded using the laser beam assignment of FIG. 7 will be described.

From the laser beam assignment of FIG. 7, the beams used to record FIG. 8A are six beams 202, 203, 204, 205, 206, and 207 indicated by ● in FIG. 8B. Of these, the beam (predetermined beam) 207 has the earliest drive timing. Here, with respect to the other beams 202 to 206, using the inter-array distance with the beam 207 and the inter-pixel distance with the pixel to be recorded by the beam 207, the drive pulse generation time (drive timing) for recording each pixel is recorded. ) Can be expressed by the following relationship using the drive pulse generation time of the beam 207 as a reference.
Drive pulse generation time = inter-array distance / main scanning speed−inter-pixel distance / main scanning speed (8)

For example, assuming that the main scanning speed is 1 m / s and the drive pulse generation time of the beam 202 is 140 μm between the arrays and the distance between the pixels is 30 μm, the drive pulse generation time of the beam 207 is used as a reference as follows. Can be calculated.
140 [μm] / 1 [μm / μs] −30 [μm] / 1 [μm / μs] = 1110 [μs] (9)

  Similarly, the drive pulse generation time can be calculated for other beams. FIG. 8C shows driving pulses for each beam. Each beam 202 to 207 is driven by a drive signal (drive pulse) having substantially constant drive time and intensity, and can form dots as shown in FIG.

  In the input image, there are isolated dots where there are no dots in adjacent pixels, and places where dots are formed when the four pixels are solidified. However, as shown in FIG. 8C, each beam is not continuously driven over a plurality of pixels, and each pixel is recorded with independent equal-width pulses using different beams. I understand that. Therefore, since each beam can form dots with the same amount of toner, it is possible to reduce variations in the density, shape, size, etc. of the dots.

  Also, consider the case of recording an image in which dots are arranged every other pixel in the main scanning direction as shown in FIG. When the beams shown in FIG. 7 are assigned, there are four beams 208, 209, 210, and 211 indicated by ● in FIG. 9B. Further, FIG. 9C shows the driving pulse of each beam. From FIG. 9 (c), even with input data having a high-frequency spatial frequency characteristic in the main scanning direction, one beam is driven once in the block, that is, only once for eight pixels. Since the number of arrays, the pitch between dots, and the main scanning speed are set so as to satisfy Expression (1), the block cycle exceeds the isolated pulse time interval at which the laser can stably emit light, and the laser emits stably. I can. Therefore, even when the spatial frequency characteristic of the input data is high frequency, stable laser emission can be performed and the density of the input data can be reproduced.

  This completes the recording process in step S107. Next, it is determined whether or not image formation for all main scans has been completed (step S108). If the image formation for all the main scans has not been completed, the processing from the cutout of the main scan image in step S105 is repeated until the image form for all the main scans is completed.

  As described above, since the driving pulse applied to each recording element is always constant regardless of the surrounding dot density, it is possible to reduce variations in the density, shape, size, and the like of the recorded dots. In addition, the lines in the main scanning direction are divided and recorded by the number of beams of the array, and the recording timing of each recording element always has an interval of a certain time or more, so that the recording element can be stably controlled regardless of the spatial frequency characteristics of the image It becomes possible to operate. Therefore, an arbitrary halftone dot shape that can be expressed by a two-dimensional pattern can be stably reproduced.

<Second Embodiment>
Hereinafter, the second embodiment will be described. In the first embodiment, a method using intra-block coordinates is shown as a method of assigning a laser beam used for recording each pixel in a cut image of main scanning. In the second embodiment, a method of using a predetermined block allocation table regardless of the intra-block coordinates will be described.

  The second embodiment differs from the first embodiment in the content of the recording beam determination process (step S106) for each pixel in FIG. The recording beam determination process of the second embodiment will be described below. Since other steps are the same as those in the first embodiment, description thereof is omitted.

  First, a block allocation table is created prior to processing. Here, as in the first embodiment, a group of pixels equal to the number of arrays of the laser oscillators 108 arranged in the main scanning direction is referred to as a block. The block allocation table is a collection of block allocations in which the laser array numbers for recording each pixel in the block are described, equal to the number of beams in the sub-scanning direction of the laser oscillator 108. Note that only the array No. is set in the block allocation table, and the beam No. used for recording uses a laser having a beam No. equal to the sub-scanning direction coordinates of the cut-out image as in the first embodiment.

  In block allocation for one block, all array numbers are allocated once without duplication. Further, the array numbers in the block may be assigned in any order. The plurality of block assignments forming the block assignment table do not need to be equal, and are a set of arbitrary block assignments. FIG. 10 shows an example of the block allocation table. In FIG. 10, the numerical value in each pixel indicates the laser array No. used for recording the corresponding pixel in the cut-out image.

  With reference to the block allocation table created in this way, a beam for recording each pixel of the cut-out image is determined. Each main scanning line of the cut-out image is divided into blocks, and the block allocation corresponding to the sub-scanning direction coordinates is referred to for each block. Here, for the blocks arranged on the line in the main scanning direction, the recording laser of each pixel is determined using the same block allocation.

  Hereinafter, the driving of the beam when recording the same binary image as FIG. 8A will be described. FIG. 11A shows an array number for recording each pixel obtained using the block allocation table of FIG. That is, the pixel at the coordinates (0, 5) in the cut-out image is recorded using the beam 215 having the array No. 2 and the beam No. 5. Similarly, the pixel at the coordinates (5, 4) in the cut-out image is recorded using the beam 214 with the array No. 7 and the beam No. 4. For other pixels, a beam to be recorded can be specified in the same manner, and six beams 212, 213, 214, 215, 216, and 217 indicated by ● in FIG. 11B are used for recording. FIG. 11C shows driving pulses of six beams. In FIG. 11C, the driving start time of the beam 214 that is driven earliest is set to zero.

  From FIG. 11C, as in the first embodiment, since dots are always recorded with a pulse having a constant width regardless of peripheral input data, variations in dot density, shape, size, and the like are reduced. be able to.

  FIG. 12 shows an array number for recording each pixel obtained by using the block allocation table of FIG. 10 in the case of recording the image of FIG. 9A. FIG. 12B shows the beam used, and FIG. 12C shows the drive pulse. Similar to the first embodiment, it can be seen that even if an image having a high spatial frequency characteristic is input, one beam is driven in a block cycle. When the number of arrays, the pitch between dots, and the main scanning speed are set so as to satisfy the formula (1), the block cycle exceeds the isolated pulse interval at which the laser can emit light stably, so that the laser emits stably. be able to. Therefore, even when the spatial frequency characteristic of the input data is high frequency, stable laser emission can be performed and the density of the input data can be reproduced.

  As described above, also in the second embodiment, it is possible to record dots having a stable dot shape, size, and density regardless of the surrounding input data and the spatial frequency characteristics of the image. It is possible to reproduce an arbitrary halftone dot shape that can be expressed by.

  In addition, the structure shown in the said embodiment is only an example, and this invention is not limited to the structure shown in figure. For example, the present invention may be applied as a part of a system constituted by a plurality of devices or may be applied to a part of an apparatus constituted by one device.

(Other embodiments)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

  101: photosensitive drum 101, 102: charging unit, 103: exposure unit, 104: development unit, 105: transfer unit, 106: cleaning unit, 107: fixing unit, 108: laser oscillator, 109: polygon mirror, 110: Fθ lens 111: Intermediate transfer drum, 112: Secondary transfer belt

Claims (7)

Recording means having a two-dimensional recording element arrangement in which a plurality of recording elements are arranged on the same main scanning line;
Recording element determination means for determining which recording element of the plurality of recording elements is used for recording for each pixel of the recording target image;
Among the recording elements that perform the recording, with reference to the driving timing of the predetermined recording element, the driving timing of the other recording elements is the distance between the predetermined recording element in the main scanning direction and the recording pixel. Using the inter-pixel distance,
An image forming apparatus comprising: drive timing determining means for driving timing = distance between main scanning directions / main scanning speed−distance between pixels / main scanning speed. Number of printing elements in the main scanning direction x distance between pixels in the main scanning direction / main scanning speed
The image forming apparatus according to claim 1, wherein a time interval necessary for stable driving of the recording element is satisfied.   The image forming apparatus according to claim 1, wherein the recording element is driven by a driving signal having a substantially constant driving time and intensity.   4. The image forming apparatus according to claim 1, wherein the recording element determination unit determines a recording element that records a pixel according to a coordinate of a pixel of a recording target image.   The image forming apparatus according to claim 1, wherein the recording element determination unit determines a recording element that records a pixel using a table prepared in advance. A method for controlling an image forming apparatus including a recording unit having a two-dimensional recording element arrangement in which a plurality of recording elements are arranged on the same main scanning line,
For each pixel of the image to be recorded, determining which recording element of the plurality of recording elements is used for recording;
Among the recording elements that perform the recording, with reference to the driving timing of the predetermined recording element, the driving timing of the other recording elements is the distance between the predetermined recording element in the main scanning direction and the recording pixel. Using the inter-pixel distance,
A control method for an image forming apparatus, comprising: driving timing = distance between main scanning directions / main scanning speed−distance between pixels / main scanning speed. A program for controlling an image forming apparatus including a recording unit having a two-dimensional recording element arrangement in which a plurality of recording elements are arranged on the same main scanning line,
For each pixel of the image to be recorded, a process for determining which recording element to use for recording from among the plurality of recording elements;
Among the recording elements that perform the recording, with reference to the driving timing of the predetermined recording element, the driving timing of the other recording elements is the distance between the predetermined recording element in the main scanning direction and the recording pixel. Using the inter-pixel distance,
A program for causing a computer to execute processing of driving timing = distance between main scanning directions / main scanning speed−distance between pixels / main scanning speed.

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