JP2008032831A - Image forming apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of obtaining an accurately corrected printed matter without being affected by the longitudinal and lateral printing/layout printing of a paper sheet even when the corrected image and the uncorrected image of image data coexist in a storage device in the image forming apparatus. <P>SOLUTION: In the image forming apparatus, a registration correction means 408 performs misregistration correction for the image data in pixel units based on misregistration correction amount. A correction flag processing part 114 adds a correction flag to the image data so as to discriminate whether or not the image data shows the image whose misregistration is corrected. When the image data is printed and output, whether or not reverse correcting processing is performed to the image data is decided based on at least either the existence of the correction flag of the image data or a paper scanning direction in the color image forming apparatus. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a so-called tandem-type image forming apparatus and method including a plurality of developing units and a transfer unit that sequentially transfers an image of each color formed by each developing unit to a transfer target.

  In recent years, for the purpose of increasing the image forming speed, a tandem type image forming apparatus is provided with the same number of developing units and photosensitive drums as the number of color materials, and sequentially transfers images of different colors onto an image conveying belt or a recording medium such as paper. The number of electrophotographic color image forming apparatuses is increasing. In such a color image forming apparatus, it is already known that there are a plurality of factors that cause registration deviation, and various countermeasures have been proposed for each factor.

  One of the factors that cause registration misalignment is the non-uniformity of the lens of the deflection scanning device, the mounting position shift, and the mounting position shift of the deflection scanning device to the color image forming apparatus main body. In that case, the scanning line is inclined or bent, and the degree of the difference varies from color to color. As a method of dealing with this registration deviation, after measuring the amount of bending of the scanning line using an optical sensor in the assembly process of the deflection scanning apparatus and adjusting the bending of the scanning line by mechanically rotating the lens, A method of fixing with an adhesive has been proposed (see Patent Document 1).

  Further, in the process of assembling the deflection scanning device into the color image forming apparatus main body, the magnitude of the scanning line tilt is measured using an optical sensor, and the deflection scanning device is mechanically tilted to adjust the scanning line tilt to adjust the color. A method of assembling the image forming apparatus main body has been proposed (see Patent Document 2).

Further, a method has been proposed in which the inclination of the scanning line and the amount of bending are measured using an optical sensor, the bitmap image data is corrected so as to cancel them, and the corrected image is formed (Patent Literature). 3). Since this method electrically corrects the image data, there is no need for a mechanical adjustment member or an adjustment process at the time of assembling, and the registration shift is less expensive than the methods described in Patent Documents 1 and 2. Can be dealt with. This electrical registration deviation correction is divided into one pixel unit correction and less than one pixel correction. As a correction method in units of one pixel, as shown in FIGS. 10A to 10C, the pixels are offset in the sub-scanning direction in units of one pixel in accordance with the correction amount of the inclination and the bending of the scanning line. Yes.
JP 2002-116394 A JP 2003-241131 A JP 2004-170755 A

  However, the above-described color image forming apparatus cannot determine whether the image data stored in the storage device is a corrected image or an uncorrected image when printing the image data stored in the storage device in the color image forming apparatus. There is a problem that a correct print result cannot be obtained.

  For example, the storage device in the color image forming apparatus stores various image data such as image data output from other printing apparatuses and image data transmitted via a network. In such a color image forming apparatus, there is a case where corrected image data is stored in a storage device for easy processing. As a result, a corrected image of image data and an uncorrected image are mixed in the storage device. To do. In such a case, when printing the image data stored in the storage device, it is determined whether the image data is a corrected image or an uncorrected image, and if the processing system is not changed according to each image data, Correctly corrected printing results cannot be obtained.

  In addition, when printing a corrected image, there is a problem that a correctly corrected printing result cannot be obtained if layout printing is executed. For example, when 2in1 printing is performed on image data in which a corrected image is formed so that the paper short direction is printed in the main scanning direction in the image forming unit, a correctly corrected printing result cannot be obtained.

  According to the present invention, even if a corrected image of image data and an uncorrected image are mixed in a storage device in the image forming apparatus, a print result corrected correctly can be obtained without being affected by vertical / horizontal printing / layout printing of paper. It is an object to provide an image forming apparatus and method that can be obtained.

  In order to achieve the above object, an image forming apparatus according to claim 1 forms an electrostatic latent image on each of a plurality of image carriers based on input image data, and develops each electrostatic latent image. Forming images corresponding to a plurality of colors, and sequentially transferring the formed images of different colors onto the transfer body to form a multiple image; and the image forming means on the transfer body A registration deviation amount storage means for storing a registration deviation amount between the images formed in the image, and a registration deviation correction amount based on the registration deviation amount between the images stored in the registration deviation amount storage means. A registration error correction amount calculation means for calculating the registration error correction of the image data in units of one pixel based on each registration error correction amount An image forming apparatus including a registration correction unit that performs correction, adds a correction flag so that it can be determined whether the image data is the corrected image data, and determines whether there is a correction flag added to the image data. Correction flag processing means, and reverse correction processing means for converting the corrected image data back to image data before correction. The correction flag processing means includes the presence / absence of the correction flag and the sheet of the image forming apparatus. Based on at least one of the scanning directions, it is determined whether to perform reverse correction processing on the image data.

  In order to achieve the above object, an image forming method according to claim 5 forms an electrostatic latent image on each of a plurality of image carriers based on input image data, and develops each electrostatic latent image. Forming images corresponding to a plurality of colors, and sequentially transferring the formed images of different colors onto the transfer body to form a multiple image; and the image forming means on the transfer body A registration deviation amount storage means for storing a registration deviation amount between the images formed in the image, and a registration deviation correction amount based on the registration deviation amount between the images stored in the registration deviation amount storage means. A registration error correction amount calculation means for calculating the registration error correction of the image data in units of one pixel based on each registration error correction amount In the image forming method of the image forming apparatus including the registration correction unit to perform, a correction flag is added so that it can be determined whether or not the image data is the corrected image data, and the correction flag added to the image data A correction flag processing step for determining the presence / absence of a correction, and a reverse correction processing step for reconverting the corrected image data into image data before correction, wherein the correction flag processing step includes the presence / absence of the correction flag and the image It is characterized in that it is determined whether to perform reverse correction processing on the image data based on at least one of the sheet scanning directions of the forming apparatus.

  According to the present invention, even when a corrected image and an uncorrected image of the image data are mixed in the storage device in the image forming apparatus, the correction is correctly performed without being affected by the vertical / horizontal printing / layout printing of the paper. Printing results can be obtained.

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

  FIG. 1 is a block diagram showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention.

  The image forming apparatus illustrated in FIG. 1 includes an electrophotographic color image forming apparatus including an image forming unit 401 and a printer controller unit 100. The printer controller unit 100 generates bitmap image information and performs processing such as storing image data in a storage device such as an HDD (Hard Disk Drive). The image forming unit 401 forms an image on a recording medium such as paper based on the image data generated by the printer controller unit 100.

  A display panel 101 is connected to the system bus 112 via a panel interface (I / F) 102. An image processing unit 104 generates bitmap data, performs color space conversion, halftoning processing, and the like on the image data, and writes the generated bitmap data in the image memory 105.

  Reference numeral 107 denotes a RAM (Random Access Memory), which is used as a work memory for the CPU 109 to control the printer controller unit 100 and stores various data. Reference numeral 108 denotes a ROM (Read Only Memory) in which a control program executed by the CPU 109, font data, and the like are written.

  A communication circuit 106 communicates with the image forming unit 401 via the video I / F circuit 111. Reference numeral 110 denotes an output buffer that converts bitmap data stored in the image memory 105 into serial data and outputs the serial data. A system bus 112 of the printer controller unit 100 connects the processing units.

  Reference numeral 103 denotes an I / F circuit that connects the HDD 201 and the system bus 112. The HDD 201 stores image data stored in the BOX, bitmap development data, and the like. Reference numeral 109 denotes a CPU (Central Processing Unit) which controls the printer controller unit 100.

  A video I / F circuit 111 is an I / F circuit for outputting image data generated by the printer controller unit 100 to the image forming unit 401. The image data is buffered by the output buffer 110, output to the video I / F circuit 111, and transmitted to the image forming unit 401.

  A correction flag processing unit 114 adds a correction flag to the image data so that when the image data is stored in the HDD 201, it can be determined whether the image data is a corrected image or an uncorrected image. The correction flag is added to the header portion of the image data. Further, when printing the image data stored in the BOX, the correction flag processing unit 114 determines whether the image data is a corrected image or an uncorrected image.

  All circuits in the printer controller unit 100 are connected to each other via a system bus 112.

  The operation of the image forming unit 401 in FIG. 1 will be described with reference to FIG.

  FIG. 2 is a cross-sectional view of a tandem type color image forming apparatus employing an intermediate transfer member as an example of the color image forming apparatus of FIG.

  In FIG. 2, the color image forming apparatus includes a charging unit, an exposure unit, a developing unit, a transfer unit, a fixing unit, and a cleaning unit.

  The charging means includes four injections for charging the photosensitive members (image bearing members) 22Y, 22M, 22C, and 22K for each of the yellow (Y), magenta (M), cyan (C), and black (K) stations. Chargers 23Y, 23M, 23C, and 23K are provided. The injection chargers 23Y, 23M, 23C, and 23K include sleeves 23YS, 23MS, 23CS, and 23KS. The photoreceptors 22Y, 22M, 22C, and 22K are obtained by applying an organic optical transmission layer to the outer periphery of an aluminum cylinder, and are rotated by a drive motor (not shown). The drive motor rotates the photoconductors 22Y, 22M, 22C, and 22K in the counterclockwise direction according to the image forming operation.

  The exposure means irradiates exposure light from the scanner units (laser scanner units) 24Y, 24M, 24C, and 24K to the photoconductors 22Y, 22M, 22C, and 22K, and selectively selects the surfaces of the photoconductors 22Y, 22M, 22C, and 22K. An electrostatic latent image is formed by exposure.

  The developing means includes four developing units 26Y, 26M, 26C, and 26K that perform Y, M, C, and K development for each station in order to visualize the electrostatic latent image. The developing means develops the electrostatic latent images formed on the photoconductors 22Y, 22M, 22C, and 22K with Y, M, C, and K developers to form respective color toner images. The developing units 26Y, 26M, 26C, and 26K include sleeves 26YS, 26MS, 26CS, and 26KS. The developing units 26Y, 26M, 26C, and 26K can be detached.

  The transfer unit rotates the intermediate transfer member 28 in the clockwise direction in order to transfer the single color toner image from the photosensitive members 22Y, 22M, 22C, and 22K to the belt-like intermediate transfer member 28. Then, the transfer unit transfers the monochromatic toner image with the rotation of the primary transfer rollers 27Y, 27M, 27C, and 27K disposed at positions facing the photoconductors 22Y, 22M, 22C, and 22K. 25Y, 25M, 25C, and 25K are toner bottles.

  In addition, the transfer unit applies an appropriate bias voltage to the primary transfer roller 27 and also makes a difference between the rotation speed of the photoconductors 22Y, 22M, 22C, and 22K and the rotation speed of the intermediate transfer body 28, thereby efficiently monochromatic. The toner image is transferred onto the intermediate transfer member 28. This is called primary transfer.

  Further, the transfer unit superimposes the single color toner image on the intermediate transfer body 28 for each station, and conveys the superimposed multicolor toner image to the secondary transfer roller 29 as the intermediate transfer body 28 rotates. Further, the recording medium 11 is nipped and conveyed from the 21a (or the manual feed tray 21b) to the secondary transfer roller 29. Then, the multicolor toner image on the intermediate transfer member 28 is transferred to the recording medium 11. The transfer unit applies an appropriate bias voltage to the secondary transfer roller 29 to electrostatically transfer the toner image. This is called secondary transfer.

  The secondary transfer roller 29 contacts the recording medium 11 at a position 29a while the multicolor toner image is transferred onto the recording medium 11, and is separated to a position 29b after the printing process.

  The fixing unit presses the fixing roller 32 that heats the recording medium 11 and the recording medium 11 against the fixing roller 32 in order to melt and fix the multicolor toner image transferred to the recording medium 11 to the recording medium 11. And a roller 33. The fixing roller 32 and the pressure roller 33 are formed in a hollow shape, and heaters 34 and 35 are incorporated therein, respectively. The fixing device 31 conveys the recording medium 11 holding the multicolor toner image by the fixing roller 32 and the pressure roller 33 and applies heat and pressure to fix the toner on the recording medium 11. The recording medium 11 after toner fixing is discharged to a discharge tray (not shown) by a discharge roller (not shown), and the image forming operation is completed.

  The cleaning unit 30 cleans the toner remaining on the intermediate transfer member 28. The cleaning unit 30 stores waste toner remaining after the four-color multicolor toner image formed on the intermediate transfer body 28 is transferred to the recording medium 11 in a cleaner container.

  The registration detection sensor 41 is disposed at a position facing the intermediate transfer body 28. A registration detection patch 64 is formed on the intermediate transfer member 28, and the amount of registration deviation of each color is determined from the patch detection timing. An example of a method of detecting the registration deviation amount by the registration detection sensor 41 is shown in FIG.

  In FIG. 3, three registration detection sensors 41a, 41b, and 41c are arranged at right angles to the scanning direction of the intermediate transfer body 28, and for detection of registration of each color of C, M, Y, and K immediately below each sensor. The patch 64 passes. As shown in FIG. 3, the registration line sensors 41a, 41b, and 41c are arranged at three positions on the left, center, and right in the scanning direction, respectively, to detect the registration deviation, thereby increasing the inclination and curvature of the scanning line. Is obtained. There is also a color image forming apparatus in which the registration detection sensors 41 are arranged only at the two left and right sides in the scanning direction. FIG. 4 shows a configuration example of the registration detection sensors 41a, 41b, and 41c.

  In FIG. 4, a registration detection sensor 41a (41b, 41c) includes a light emitting element 51, a light receiving element 52 such as a photodiode, an IC (not shown) that processes light reception data output from the light receiving element 52, and the like. It consists of a holder (not shown) that houses it.

  The issuing element 51 includes an LED (Light Emitting Diode) or the like. The light receiving element 52 detects the reflected light intensity of the light irradiated from the light emitting element 51 to the intermediate transfer body 28 and reflected from the registration detection patch 64 formed on the intermediate transfer body 28. The configuration example shown in FIG. 4 is configured to detect regular reflection light, but is not limited thereto, and may detect irregular reflection light. An optical element such as a lens (not shown) may be used for coupling the light emitting element 51 and the light receiving element 52.

  Next, the occurrence of registration deviation will be described with reference to FIG.

  FIG. 5 is a diagram for explaining registration deviation.

  In FIG. 5, reference numeral 301 denotes an ideal scanning line, and scanning is performed perpendicularly to the respective rotation directions of the photoconductors 22Y, 22M, 22C, and 22K (hereinafter simply referred to as “photoconductor 22”). Reference numeral 302 denotes an actual scanning line in which inclination and curvature are generated due to the positional accuracy and diameter deviation of the photosensitive member 22 and the positional accuracy of the optical system in each color scanner unit 24Y, 24M, 24C, and 24K. Since the inclination and curvature of the scanning line are different for each of the C, M, Y, and K image stations, registration deviation occurs in the image in which the toner images of all colors are transferred onto the intermediate transfer body 28.

  In the present embodiment, an ideal scanning line 301 and actual scanning at a plurality of points (point B, point C, point D) with the point A serving as the scanning start position of the print area as a reference point in the main scanning direction. The amount of deviation of the line 302 in the sub-scanning direction is measured. Each point where the amount of deviation is measured is divided into a plurality of regions (region Pa-Pb is region 1, region Pb-Pc is region 2, and region Pc-Pd is region 3). The slopes of the scanning lines in each region are approximated by straight lines (Lab, Lbc, Lcd) connecting them. Here, the main scanning direction is the illustrated X direction, and the sub-scanning direction is the illustrated Y direction.

  Therefore, when the difference in the amount of deviation between points (m1 in the region 1, m2-m1 in the region 2, m3-m2 in the region 3) is a positive value, the scanning line of the corresponding region has an upward slope. In the case of a negative value, it indicates that it has a downward slope.

  Next, the configuration of the correction processing unit 113 in FIG. 1 will be described with reference to FIGS. 6 (a) and 6 (b).

  6A is a block diagram showing a schematic configuration of the correction processing unit 113 and the image forming unit 401 in FIG. 1, and FIG. 6B is a block diagram showing a schematic configuration of the registration correction unit in FIG. 6A. FIG. In FIG. 6A, the video I / F circuit 111 disposed between the correction processing unit 113 and the image forming unit 401 shown in FIG. 1 is omitted.

  The printer controller unit 100 generates raster image data that can be printed from print data received from a computer device (not shown), and outputs RGB data and attribute data indicating the data attribute of each pixel for each pixel.

  The image processing unit 104 has color conversion means (not shown), and converts the RGB data into CMYK data according to the toner color of the image forming unit 401 by the color conversion means, and stores the CMKY data and attribute data in the image memory 105. . The image memory 105 temporarily stores the generated raster image data, and functions as a page memory for storing raster image data for one page or a band memory for storing data for a plurality of lines.

  Reference numerals 408C, 408M, 408Y, and 408K denote registration correction units that correct registration deviation due to the inclination and curvature of the scanning line. Details of processing in the registration correction means 408C, 408M, 408Y, and 408K will be described later.

  Registration deviation of the bitmap image is corrected by registration correction means 408C, 408M, 408Y, and 408K based on the raster image data stored in the image memory 105. Then, the bitmap image is transmitted to the video I / F circuit 111 via the output buffer 110 shown in FIG. 1, and is subjected to pulse width modulation (PWM) in the video I / F circuit 111, and the scanner unit 24C. , 24M, 24Y, and 24K exposure times.

  Next, a registration deviation correction method according to the present embodiment will be described.

  (1) First, registration deviation profile information 413C, 413M, 413Y, 413K (hereinafter simply referred to as “registration deviation profile information 413”) is stored in the registration deviation amount storage unit 403 in the image forming unit 401. .

  (2) Based on the registration deviation profile information 413 and the engine profile information stored in the engine profile storage means 412, the registration deviation correction amount calculation means 407C, 407M, 407Y, 407K calculate the correction amount of each pixel of each color. Hereinafter, the registration deviation correction amount calculation means 407C, 407M, 407Y, and 407K are referred to as “registration deviation correction amount calculation means 407”.

  (3) Registration correction means 408C, 408M, 408Y, and 408K (hereinafter simply referred to as “registration correction means 408”) correct bitmap data based on the calculated correction amount of each pixel.

  Hereinafter, each of (1) to (3) will be described in detail.

  In (1), registration deviation profile information 413 is acquired and stored in the registration deviation amount storage unit 403 in the image forming unit 401. As shown in FIG. 5, the registration shift profile information 413 is, for example, a shift amount in the sub-scanning direction between the actual scanning line 302 and the ideal scanning line 301 measured at a plurality of points on the scanning line for each color. . An example of registration deviation profile information 413 stored in the registration deviation amount storage unit 403 is shown in FIG.

  In FIG. 7, registration deviation profile information 413 is created based on the registration deviation occurrence state shown in FIG. 5, and includes the widths of regions 1 to 3 and the inclination of the scanning line. . Note that the format of the profile information is not limited to that shown in the drawing, and any profile information can be used as long as the characteristics of the scan line inclination and curvature can be understood.

  A method for acquiring the registration error profile information 413 stored in the registration error amount storage unit 403 will be described.

  As a first method, there is a method of measuring and acquiring a registration shift amount in a manufacturing process of a color image forming apparatus. As a second method, the registration detection sensors 41 a to 41 c described above are used to obtain the detection result of the registration detection patch 64 formed on the intermediate transfer body 28.

  As a third method, a registration deviation measurement chart 210 as shown in FIG. 8A is output by a color image forming apparatus, and an image of the chart 210 is read by a commercially available image scanner or the like to be converted into electronic information. Profile information is acquired from the electronic information. In the registration deviation measurement chart shown in FIG. 8A, registration deviation measurement patches 65 of C, M, Y, and K colors are formed so as to be aligned on the scanning line 66. However, in actuality, as shown in FIG. 8B, the registration deviation measurement patch 65 a is displaced from the scanning line 66. Therefore, it is possible to acquire the profile information by measuring the deviation amount from the electronic information.

  In the above (2), the registration deviation correction amount calculation unit 407 calculates a correction amount for canceling the registration deviation based on the registration deviation profile information 413 stored in the registration deviation amount storage unit 403. Then, the calculated correction amount is output to the registration correction means 408. Specifically, when the coordinate data in the main scanning direction is x (dot) and the registration deviation correction amount in the sub-scanning direction is Δy (dot), Δy of each of the regions 1 to 3 shown in FIG. (The image forming resolution is r (dpi)).

Region 1: Δy1 = x * (m1 / L1)
Region 2: Δy2 = m1 / r + (x− (L1 / r)) * ((m2−m1) / (L2−L1))
Region 3: Δy3 = m2 / r + (x− (L2 / r)) * ((m3−m2) / (L3−L2))
Here, L1, L2, and L3 are distances (mm) in the main scanning direction from the printing start position to the left end of the region 1, the region 2, and the region 3, respectively. m 1, m 2, and m 3 are deviation amounts of the ideal scanning line 301 and the actual scanning line 302 at the left end of the regions 1, 2, and 3.

The inclination of the scanning line in each region is obtained from the deviation at the measurement point. The exposure unit profile data (registration shift profile information) Δys at each pixel in all regions is
Δys = x * (m1 / L) (0 ≦ x <L1)
m1 / r + (x- (L1 / r)) * ((m2-m1) / (L2-L1))
(L1 ≦ x <L1 + L2)
m2 / r + (x- (L2 / r)) * ((m3-m2) / (L3-L2))
(L1 + L2 ≦ x ≦ L1 + L2 + L3)
After this Δys is determined, the value of x at which Δys reaches the number of integer dots in the image forming resolution is calculated, and the vertical reading position of the coordinate conversion means 802 is changed by the x.

  The engine profile information stored in the engine profile storage unit 412 includes offset amount information from the reference point in the paper size, scanning direction information of each color beam, and a recording medium conveyance speed (not shown). An example of engine profile information is shown in FIG.

  In FIG. 9, the paper information is offset amount information. The scanner information is scanning direction information, and is information on which direction of Forward / Reverse scanning is to be performed. If the scanning direction is different, it is necessary to add a sign to the correction amount accordingly. For example, the calculation is performed assuming that the sign when the scanning direction is Forward is negative and the sign when Reverse is positive with respect to the registration deviation amount.

  If the printing speed is different, it may be necessary to change the correction amount accordingly. For example, when the image forming speed (recording medium conveyance speed) is ½ times the normal speed, the scanning speed is not changed, and image output is performed in one of the two scanning operations, and image output is performed in the remaining one time. Not performed. The correction amount in this case needs to be ½ that when the image forming speed is 1 ×. Further, it is necessary to calculate the correction amount using profile data of an area corresponding to the paper size.

  In (3), the registration correction unit 408 corrects the bitmap data based on the calculated correction amount of each pixel.

  The registration correction unit 408 includes a coordinate conversion unit 802 and a line buffer 803 as shown in FIG. The line buffer 803 is a memory in units of lines, and stores information for the correction amount from the image memory 105 in units of lines.

  The coordinate conversion unit 802 corrects an integer part of the registration deviation correction amount Δy based on the coordinate position data in the main scanning direction and the scanning direction and the registration deviation correction amount Δy obtained from the registration deviation correction amount calculation unit 407. I do. That is, the coordinate conversion unit 802 performs registration deviation correction in units of one pixel (1 dot) and reconstructs output image data. The reconstruction of the output image data means that the image data to be output is configured by correcting the registration deviation and converting the coordinates.

  Next, the flow of correction processing in the coordinate conversion means 802 as registration correction means will be described with reference to FIGS. 10 (a) to 10 (c).

  The coordinate conversion means 802 determines the sub-scanning direction of the image data stored in the image memory 105 according to the value of the integer part of the registration deviation correction amount Δy obtained from the registration deviation information of the scanning line approximated by a straight line ( The coordinates in the Y direction are offset (FIG. 10A).

  For example, when the data of the nth line is reconstructed by the coordinate position in the sub-scanning direction, the coordinate position in the main scanning direction is set to X. Then, in the area (1) in the X coordinate in the main scanning direction, the registration deviation correction amount Δy is 0 or more and less than 1, and the nth line data is read from the image memory 105 (bitmap memory) (FIG. 10 ( b)).

  In the area (2) shown in the figure, the registration deviation correction amount Δy is 1 or more and less than 2, and the coordinate conversion is performed so that the bitmap image at the position offset by one line, that is, the data of the (n + 1) th line is read from the bitmap memory. Process.

  Similarly, coordinate conversion processing is performed so that the data of the (n + 2) th line is read out in the area (3) and the data of the (n + 3) th line is read out in the area (4). The output image data is reconstructed by the above method. FIG. 10C shows an exposure image in which the image carrier is exposed to image data that has been subjected to registration shift correction in pixel units by the coordinate conversion means 802.

  Next, the flow of image data correction processing executed during the printing process in the color image forming apparatus of FIG. 1 will be described with reference to FIG.

  FIG. 11 is a flowchart showing the flow of image data correction processing executed during printing processing.

  In FIG. 11, first, BOX print processing for printing image data stored in the BOX via the display panel 101 of the printer controller unit 100 or by a remote UI or the like is started. At this time, it is determined whether or not layout printing is set for the image data to be printed out (step S101). As a result of this determination, if layout printing is set for the image data (YES in step S101), the correction flag processing unit 114 determines whether the image data is a corrected image or an uncorrected image (step S102). The correction flag processing unit 114 determines whether the image is a corrected image or an uncorrected image depending on whether a correction flag is added to the image data.

  If it is determined in step S102 that the image data is an uncorrected image (NO in step S102), the process proceeds to step S104. On the other hand, if the image data is a corrected image (YES in step S102), reverse correction processing is performed on the image data (step S103). The reverse correction process is a process for converting image data corrected by the correction processing unit 113 back to image data before correction. The processing method is the same as the registration correction method described above, and the registration deviation profile information and the engine profile information are rewritten by the CPU 109 for reverse correction. Thereafter, correction processing is performed to obtain bitmap data after reverse correction. When image data is stored in the HDD 201 after the correction processing is completed, the correction flag processing unit 114 deletes the correction flag added to the image data.

  Next, in step S104, it is determined whether or not the processing in step S102 has been performed on all image data to be printed out. As a result, when the process of step S102 is performed on all the image data to be printed (YES in step S104), an image composition process based on the layout printing set in the image data is performed (step S105).

  Next, after determining whether the paper scanning direction and the correction direction of the image forming unit 401 are the main scanning direction or the sub-scanning direction (step S106), registration correction processing is performed on the combined image data (step S107). The image data is printed out (step S114). Thereby, even if layout printing is executed, a correctly corrected printing result can be obtained. Further, even when the image forming unit 401 performs 2-in-1 printing of image data on which a correction image is formed so as to print in the paper short direction as the main scanning direction, a correctly corrected printing result can be obtained. . Note that the paper scanning direction means the paper orientation (vertical or horizontal) with respect to the printing scanning direction.

  On the other hand, if the result of determination in step S101 is that layout printing has not been set for the image data (NO in step S101), it is determined whether the image data in the BOX is a corrected image or an uncorrected image (step S108).

  If the result of determination in step S108 is that the image data in the BOX is an uncorrected image (NO in step S108), registration correction processing is performed on the image data in the BOX (step S110). As a result, even if the image data in the BOX is an uncorrected image, a printing result obtained by performing registration correction can be obtained.

  If it is determined in step S108 that the image data in the BOX is a corrected image (YES in step S108), the correction flag processing unit 114 determines the paper scanning direction and the image data correction direction (main scanning direction or sub-scanning direction). Are determined to match (step S109). Here, for example, when the A4 size paper scanning direction is horizontal and the correction direction of the image data is the vertical direction (main scanning direction), it is determined that they do not match.

  If the paper scanning direction matches the image data correction direction, it is determined that reverse correction is not necessary (NO in step S111), and the image data is printed out as it is (step S114).

  On the other hand, the correction flag processing unit 114 determines that reverse correction is necessary when the paper scanning direction does not match the image data correction direction (YES in step S111). Then, after performing reverse correction processing (step S112) on the image data, image data correction processing is performed in accordance with the paper scanning direction (step S113), and the image data is printed out (step S114). Since the reverse correction processing is performed according to whether the paper scanning direction and the image data correction direction match, it is possible to simplify the entire processing by omitting useless processing.

  According to the above embodiment, when printing the image data stored in the storage device in the color image forming apparatus, even when the corrected image of the image data and the uncorrected image are mixed in the storage device. Thus, it is possible to obtain a correctly corrected printing result without being affected by vertical / horizontal printing / layout printing of the paper.

  The present invention is not limited to the configuration of the above-described embodiment, and any configuration can be used as long as the functions shown in the claims or the functions of the configuration of the present embodiment can be achieved. Is also applicable. The present embodiment can also be applied to an image forming apparatus including a photosensitive belt instead of the intermediate transfer member and the photosensitive member, and an image forming apparatus including a single photosensitive member. Further, the present invention can be applied to an apparatus that directly transfers from a photosensitive member to a recording sheet without using an intermediate transfer member.

  An object of the present invention is to supply a storage medium storing software program codes for realizing the functions of the above embodiments to a system or apparatus, and a computer such as the system reads the program codes stored in the storage medium. It is also achieved by executing. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the program code and the storage medium storing the program code constitute the present invention. . The computer may be a CPU, MPU, or the like.

  As a storage medium for supplying the program code, for example, a removable disk, a hard disk, a magneto-optical disk, an optical disk, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used. The program code may be downloaded via a network. Optical disks include CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD + RW, and the like.

  The functions of the above-described embodiments are not only realized by executing the program code read by the computer. In some cases, an OS (operating system) running on the computer performs part or all of the actual processing based on the instruction of the program code, and the functions of the above-described embodiments are realized by the processing. included.

  Further, the program code read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. Thereafter, based on the instruction of the next program code, the CPU or the like provided in the function expansion board or function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing. Cases are also included.

1 is a block diagram showing a schematic configuration of a color image forming apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a tandem type color image forming apparatus employing an intermediate transfer member that is an example of the color image forming apparatus of FIG. 1. It is a figure which shows an example of the detection method of the registration shift | offset | difference amount by a registration detection sensor. It is a figure which shows the structural example of a registration detection sensor. It is a figure explaining a registration shift. (A) is a block diagram showing a schematic configuration of a correction processing unit and an image forming unit in FIG. 1, and (b) is a block diagram showing a schematic configuration of a registration correction unit of FIG. 6 (a). It is a figure which shows an example of the registration shift | offset | difference profile information memorize | stored in a registration shift | offset | difference amount memory | storage means. (A) is a figure which shows an example of the chart for registration deviation | shift measurement, (b) is a figure which shows the state which the patch for registration deviation | shift measurement shifted | deviated from the scanning line. It is a figure which shows an example of the engine profile information memorize | stored in an engine profile memory | storage means. (A)-(c) is a figure explaining the method of the registration shift correction | amendment per pixel. 6 is a flowchart illustrating a flow of image data correction processing executed during printing processing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Printer controller part 101 Display panel 104 Image processing part 105 Image memory 109 CPU
110 Output Buffer 111 Video I / F Circuit 113 Correction Processing Unit 114 Correction Flag Processing Unit 201 Hard Disk (HDD)
401 Image forming units 407C, 407M, 407Y, 407K Registration deviation correction amount calculation means 408C, 408M, 408Y, 408K Registration correction means 412 Engine profile storage means 413C, 413M, 413Y, 413K Registration deviation profile information

Claims (8)

An electrostatic latent image is formed on each of a plurality of image carriers based on image data, each electrostatic latent image is developed to form an image corresponding to a plurality of colors, and images of different colors formed are formed. Image forming means for sequentially transferring images on a transfer body to form multiple images, and registration deviation amount storage means for storing registration deviation amounts between the images formed on the transfer body by the image forming means. A registration deviation correction amount calculating means for calculating a registration deviation correction amount based on a registration deviation amount between the images stored in the registration deviation amount storage means, and based on each registration deviation correction amount. An image forming apparatus comprising registration correction means for correcting registration deviation of the image data in units of one pixel.
A correction flag processing means for adding a correction flag so as to determine whether or not the image data is the corrected image data, and determining the presence or absence of the correction flag added to the image data;
Reverse correction processing means for reconverting the corrected image data into image data before correction,
The correction flag processing means determines whether to perform reverse correction processing on the image data based on the presence / absence of the correction flag and at least one of a sheet scanning direction of the image forming apparatus. Forming equipment.   The correction flag processing means causes the reverse correction processing means to perform reverse correction processing when the correction processing scanning direction of the image data and the paper scanning direction of the image forming apparatus are different, so that the paper scanning of the image forming apparatus is performed. The image forming apparatus according to claim 1, wherein correction processing is performed in a direction that coincides with the direction to perform printing processing.   3. The image according to claim 1, wherein the correction flag processing unit causes the reverse correction processing unit to perform reverse correction processing on the image data when a correction flag is added to the image data. Forming equipment. A judgment unit for judging whether layout printing is set for the image data;
When it is determined that layout printing has been set for the image data, the correction flag processing means performs image composition processing based on the layout print setting for the image data after the reverse correction processing, and performs the composition processing. The image forming apparatus according to claim 3, wherein correction processing is performed on subsequent image data. Based on the input image data, an electrostatic latent image is formed on each of a plurality of image carriers, and each of the electrostatic latent images is developed to form an image corresponding to a plurality of colors. Image forming means for sequentially transferring the images on the transfer body to form a multiple image, and a registration shift for storing the registration shift amount between the images formed on the transfer medium by the image forming means An amount storage means, a registration error correction amount calculation means for calculating a registration error correction amount based on a registration error amount between the images stored in the registration error amount storage means, and each registration error correction. An image forming apparatus comprising: a registration correction unit that corrects registration deviation of the image data in units of one pixel based on the amount; In the image forming method,
A correction flag processing step of adding a correction flag so that it can be determined whether the image data is the corrected image data, and determining the presence or absence of the correction flag added to the image data;
A reverse correction processing step for reconverting the corrected image data into image data before correction,
The correction flag processing step determines whether or not to perform reverse correction processing on the image data based on at least one of the presence or absence of the correction flag and the paper scanning direction of the image forming apparatus. Forming method.   In the correction flag processing step, when the correction processing scanning direction of the image data is different from the paper scanning direction of the image forming apparatus, reverse correction processing is performed in the reverse correction processing step, and the paper of the image forming apparatus 6. The image forming method according to claim 5, wherein a printing process is performed by performing a correction process in a direction that coincides with the scanning direction.   The said correction flag process step makes the said image data perform a reverse correction process in the said reverse correction process step, when the correction flag is added to the said image data. Image forming method. A determination step of determining whether layout printing is set for the image data;
When it is determined that layout printing has been set for the image data, the correction flag processing means performs image composition processing based on the layout print setting for the image data after the reverse correction processing, and performs the composition processing. 8. The image forming method according to claim 7, wherein correction processing is performed on the subsequent image data.

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