Patent Publication Number: US-2023161285-A1

Title: Image forming apparatus, transfer device, and storage medium

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is based on and claims priority pursuant to 35 U.S.C. §119(a) to Japanese Patent Application Nos. 2021-191075, filed on Nov. 25, 2021, and 2022-154792, filed on Sep. 28, 2022, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein. 
     BACKGROUND 
     Technical Field 
     Embodiments of this disclosure relate to an image forming apparatus, a transfer device, and a storage medium. 
     Related Art 
     Technologies have been developed that generate an image misregistration correction image for correcting a misregistration of an image or generate and print a check image for checking a state of an image forming apparatus. For example, a technology is known that changes the arrangement of a large number of patch images in a chart image to reduce variations of colorimetric data of the chart image including a combination of various patch images. 
     SUMMARY 
     In an embodiment of the present disclosure, there is provided an image forming device that includes circuitry. The circuitry generates an image pattern in which two or more types of patch images are combined and changes a value of image data around at least one type of patch image of the two or more types of patch images to less than a maximum value of image data of the at least one type of patch image when the two or more types of patch images are combined. 
     In another embodiment of the present disclosure, there is provided an image forming device that includes circuitry. The circuitry generates an image pattern in which two or more types of patch images are combined and reverses black and white of at least one type of patch image of the two or more types of patch images when the two or more types of patch images are combined. 
     In still another embodiment of the present disclosure, there is provided a non-transitory storage medium storing a plurality of instructions which, when executed by one or more processors, cause the processors to execute a method. The method includes generating an image pattern in which two or more types of patch images are combined and changing a value of image data around at least one type of patch image of the two or more types of patch images to less than a maximum value of the at least one type of patch image when the two or more types of patch images are combined. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete appreciation of the disclosure and many of the attendant advantages and features thereof can be readily obtained and understood from the following detailed description with reference to the accompanying drawings, wherein: 
         FIG.  1    is a schematic view of a printer of an image forming apparatus according to a first embodiment of the present disclosure; 
         FIG.  2    is a diagram illustrating a configuration of an image forming device disposed in the image forming apparatus according to the first embodiment of the present disclosure; 
         FIG.  3    is a diagram illustrating a configuration of a light beam scanner disposed in the image forming apparatus according to the first embodiment of the present disclosure; 
         FIG.  4 A  is a diagram illustrating a configuration of an image forming controller and a light beam scanner disposed in the printer of the image forming apparatus according to the first embodiment of the present disclosure; 
         FIG.  4 B  is a diagram illustrating a hardware configuration of a printer controller disposed in the image forming apparatus, according to the first embodiment of the present disclosure; 
         FIG.  5    is a diagram illustrating a functional configuration of a reference clock generator and a voltage-controlled oscillator (VCO) clock generator in a pixel clock generator disposed in the printer of the image forming apparatus according to the first embodiment of the present disclosure; 
         FIG.  6    is a diagram illustrating a functional configuration of a writing-start-position controller disposed in the printer of the image forming apparatus according to the first embodiment of the present disclosure; 
         FIG.  7    is a timing chart illustrating an example of control processing of a writing start position in a main scanning direction by the writing-start-position controller disposed in the printer of the image forming apparatus according to the first embodiment of the present disclosure; 
         FIG.  8    is a timing chart illustrating an example of control processing of a writing start position in a sub-scanning direction by the writing-start-position controller disposed in the printer of the image forming apparatus according to the first embodiment of the present disclosure; 
         FIG.  9    is a diagram illustrating a functional configuration of a printer controller disposed in the printer of the image forming apparatus according to the first embodiment of the present disclosure; 
         FIG.  10    is a flowchart of an example of control processing of a laser diode (LD) unit performed by the image forming apparatus according to the first embodiment of the present disclosure; 
         FIG.  11    is a diagram illustrating an image pattern to be formed on an intermediate transfer belt, and a sensor, in the image forming apparatus according to the first embodiment of the present disclosure; 
         FIG.  12    is a diagram illustrating sensors and a synthesized pattern formed on an intermediate transfer belt by the image forming apparatus according to the first embodiment of the present disclosure; 
         FIG.  13    is a diagram illustrating sensors and a synthesized image pattern formed on the intermediate transfer belt by the image forming apparatus according to the first embodiment of the present disclosure; 
         FIG.  14    is a diagram illustrating an example of the positions of sensors and an image pattern to be formed on a recording sheet by the image forming apparatus according to the first embodiment of the present disclosure; 
         FIG.  15    is a diagram illustrating an example of the positions of sensors and a synthesized image pattern formed on the recording sheet by the printer of the image forming apparatus according to the first embodiment of the present disclosure; 
         FIG.  16    is a diagram illustrating a configuration of an image forming device disposed in an image forming apparatus according to a second embodiment of the present disclosure; 
         FIG.  17    is a diagram illustrating a schematic configuration of an inkjet recording apparatus according to a third embodiment of the present disclosure; 
         FIG.  18    is a diagram illustrating an arrangement of two scanners disposed in the inkjet recording apparatus according to the third embodiment of the present disclosure; and 
         FIG.  19    is a block diagram illustrating a control configuration of the inkjet recording apparatus according to the third embodiment of the present disclosure. 
     
    
    
     The accompanying drawings are intended to depict embodiments of the present invention and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. Also, identical or similar reference numerals designate identical or similar components throughout the several views. 
     DETAILED DESCRIPTION 
     In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that have a similar function, operate in a similar manner, and achieve a similar result. 
     Referring now to the drawings, embodiments of the present disclosure are described below. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. 
     First Embodiment 
       FIG.  1    is schematic view of a printer of an image forming apparatus, according to a first embodiment of the present disclosure. A printer  100  (an example of the transfer device) of the image forming apparatus according to the present embodiment includes an intermediate transfer unit in the middle of the printer  100 . The intermediate transfer unit is provided with an intermediate transfer belt  10  that is an endless belt. The intermediate transfer belt  10  is wound around three support rollers  14  to  16  and is driven to rotate in a clockwise direction indicated by an arrow in  FIG.  1   . An intermediate transferor cleaner  17  that removes residual toner remaining on the intermediate transfer belt  10  after image transfer is disposed at the right side of a second support roller  15 . 
     An image forming device  20  is provided with the intermediate transfer belt  10  between the first support roller  14  and the second support roller  15 . The image forming device  20  includes photoconductor units  40 , charging units, developing units, and cleaning units. The photoconductor units  40  for respective colors of yellow (Y), magenta (M), cyan (C), and black (K) are disposed along a movement direction of the intermediate transfer belt  10 . Each charging unit charges a photoconductor drum disposed in the corresponding one of the photoconductor units  40 . Each developing unit (an example of a toner developing unit) develops a latent image formed on the corresponding photoconductor drum by a light beam scanner  21  described below. Each cleaning unit removes toner remaining on the corresponding photoconductor drum. The photoconductor unit  40  functions as an example of a transfer unit that transfers a toner image obtained by developing a latent image by the developing unit onto the intermediate transfer belt  10  (an example of a transferor). The image forming device  20  is detachably attached to a body of the printer  100 . 
     The light beam scanner  21  is disposed above the image forming device  20  and irradiates each photoconductor drum (an example of an image bearer) of the photoconductor unit  40  for each color with laser light for image formation to form the latent image. The light beam scanner  21  functions as an example of an optical writing device that forms the latent image by scanning and irradiating the photoconductor drum with a light beam corresponding to an image pattern. The image pattern is an example of an image pattern in which two or more types of patch images such as an image misregistration correction pattern and an image density adjustment pattern are combined. A secondary transfer unit  22  is disposed below the intermediate transfer belt  10 . The secondary transfer unit  22  is disposed to push up the intermediate transfer belt  10  to press the intermediate transfer belt  10  against a third support roller  16 . With such a configuration, the toner image on the intermediate transfer belt  10  is transferred onto a sheet. That is, the secondary transfer unit  22  functions as an example of a transfer unit that transfers the toner image formed on the intermediate transfer belt  10  onto the sheet (an example of a transferor). A fixing unit  25  that fixes the toner image transferred onto the sheet is disposed beside the secondary transfer unit  22 . The sheet onto which the toner image is transferred is conveyed to the fixing unit  25 . A heating pressure roller  27  is pressed against a fixing belt  26  that is an endless belt in the fixing unit  25 . A sheet reverse unit  28  is disposed below the secondary transfer unit  22  and the fixing unit  25 . The sheet reverse unit  28  reverses the front and back of the sheet immediately after the toner image is formed on the front side and sends out the sheet in order to record the toner image also on the back side. 
     In a case where a document is on a document feeding table  30  of an automatic document feeder (ADF)  400 , the document is conveyed onto an exposure glass  32  when a start switch of an operation unit in the image forming apparatus is pressed. When no document is on the ADF  400 , a scanner of an image reading unit  300  is driven to read a document manually placed on the exposure glass  32 . Thus, a first carriage  33  and a second carriage  34  are driven to scan and read the document. The light is emitted onto the exposure glass  32  from a light source on the first carriage  33 . The reflected light from the document surface is reflected by a first mirror on the first carriage  33  toward the second carriage  34 . The light is reflected by the mirror on the second carriage  34  to be imaged on a reading sensor  36  such as a charge-coupled device (CCD) through an imaging lens  35 . The printer  100  generates recording data of each color of Y, M, C, and K based on the image signals obtained by the reading sensor  36 . 
     The intermediate transfer belt  10  of the printer  100  starts driving to rotate and preparation for image formation for each of the image forming devices  20  when a start switch is operated, when an image output is instructed from, for example, a personal computer (PC), or when an image output instruction is received through facsimile communication. Next, the printer  100  starts an image forming sequence of each color image and irradiates an exposure laser beam modulated based on recording data for each color onto the photoconductor drum for each color. Thus, the printer  100  superimposes and transfers the toner images of the colors Y, M, C, and K onto the intermediate transfer belt  10  by image forming processes for the colors Y, M, C, and K to form a single toner image on the intermediate transfer belt  10 . The printer  100  feeds the sheet to the secondary transfer unit  22  at a timing such that the leading end of the sheet enters the secondary transfer unit  22  at the same time as the leading end of the toner image enters the secondary transfer unit  22 . As a result, the printer  100  transfers the toner image on the intermediate transfer belt  10  onto the sheet. The printer  100  conveys the sheet onto which the toner image has been transferred to the fixing unit  25 . Thus, the toner image is fixed onto the sheet in the fixing unit  25 . 
     The image forming apparatus selectively drives one of feed rollers  42  of a feed table  200  to rotate. The sheets are fed from one of sheet trays  44  disposed in multiple stages in a sheet feeder unit  43 . Thus, one sheet is separated by a separation roller  45  and is conveyed to a conveying roller unit  46 . Next, the image forming apparatus guides the sheet to a conveying roller unit  48  in the printer  100  by conveying the sheet by a conveying roller  47 , and stops the sheet by causing the sheet to come into contact with a registration roller pair  49  of the conveying roller unit  48 . Thus, the image forming apparatus conveys the sheet to the secondary transfer unit  22  at the above-described timing. A user can insert the sheet on a manual sheet tray  51  disposed in the image forming apparatus to feed the sheet. When the user inserts the sheet onto the manual sheet tray  51 , the image forming apparatus drives to rotate a feed roller  50  to separate one of the sheets on the manual sheet tray  51 , draws the sheet into a manual feed passage  53 , and causes the sheet to come into contact with the registration roller pair  49  to stop the sheet. 
     The image forming apparatus guides the sheet ejected after the fixing process in the fixing unit  25  to an ejection roller  56  by a switching claw  55  and stacks the sheet on a sheet ejection tray  57 . The image forming apparatus guides the sheet to the sheet reverse unit  28  by the switching claw  55 , reverses the sheet through the sheet reverse unit  28 , guides the sheet again to the transfer position, and records an image also on the back surface. Thus, the ejection roller  56  ejects the sheet onto the sheet ejection tray  57 . On the other hand, the intermediate transferor cleaner  17  removes the residual toner from the intermediate transfer belt  10  after image transfer to prepare for the next image formation. 
       FIG.  2    is a diagram illustrating an example of a configuration of the image forming device  20  disposed in the image forming apparatus according to the first embodiment of the present disclosure. The image forming device  20  includes four sets of image forming units and four sets of light beam scanners  21  to form color images in which images of four colors of yellow, magenta, cyan, and black are superimposed. The light beam scanner  21  is provided with a laser diode (LD) controller to be described later. The LD controller selectively emits a light beam by driving and modulating the light beam according to image data. The light beam emitted from the light beam scanner  21  is deflected by a polygon mirror rotated by a polygon motor, passes through an f-θ lens, is reflected by a return mirror, and scans the photoconductor drum. 
     The image forming device  20  includes a charger  18 , a developing unit  8 , a transfer unit  7  (an example of a transfer unit), a cleaning unit  9 , and a static eliminator  19  around the photoconductor drum for each color. The transfer unit  7  transfers the toner image formed on the photoconductor drum to the intermediate transfer belt  10  (an example of a transferor). The static eliminator  19  eliminates static electricity from the photoconductor drum. The image forming device  20  forms a first color image on the intermediate transfer belt  10  by charging, exposure, development, and transfer which are ordinary electrophotographic processes, and transfers a second color image, a third color image, and a fourth color image in this order to form a color toner image (color image) in which images of four colors are superimposed. 
     Further, the image forming device  20  causes the secondary transfer unit  22  to transfer the toner image formed on the intermediate transfer belt  10  onto a conveyed recording sheet (paper), thereby forming a color image in which four color images are superimposed on each other on the recording sheet. The image forming device  20  also includes the intermediate transferor cleaner  17  for removing the toner image on the intermediate transfer belt  10 . The image forming device  20  includes sensors  sr   1  to  sr   3  for detecting the image pattern (for example, the image misregistration correction pattern or the image density adjustment pattern) formed on the intermediate transfer belt  10 . The sensors  sr   1  to  sr   3  are reflection-type optical sensors and detect the image pattern formed on the intermediate transfer belt  10 . The printer  100  corrects, for example, image misregistrations in the main scanning direction and the sub-scanning direction between the respective colors, an image magnification in the main scanning direction, and the image density based on the detection results of the image pattern by the sensors  sr   1  to  sr   3 . 
     Then, the image forming device  20  fixes the image on the recording sheet by a fixing device. The image forming device  20  is disposed near an exit of the fixing device and includes sensors  sr   4  and  sr   5  that detect the image pattern formed on the recording sheet (an example of a print medium). The sensors  sr   4  and  sr   5  are image reading sensors such as a charge-coupled device (CCD) or a contact image sensor (CIS). The sensors  sr   4  and  sr   5  are disposed at positions where the image patterns formed at the four corners on the recording sheet can be detected. The printer  100  executes correction of the image position with respect to the recording sheet, correction of the image position on the back surface with respect to the image position on the front surface, and correction of the image density based on the detection results of the sensors  sr   4  and  sr   5 . The image forming device  20  includes a toner bottle containing toner to be supplied to the developing unit for each color. 
       FIG.  3    is a diagram illustrating a configuration of the light beam scanner disposed in the image forming apparatus, according to the first embodiment of the present disclosure. Specifically,  FIG.  3    is a top view of the light beam scanner  21 . The light beam scanners  21  of the respective colors have the same configuration. In the light beam scanner  21 , the light beam from an LD unit passes through a cylinder lens (CYL)  302 , is incident on a polygon mirror  303 , is deflected by the rotation of the polygon mirror  303 , passes through an f-θ lens  304 , and scans the photoconductor drum by a return mirror  305 . 
     The light beam scanner  21  is provided with a synchronous mirror  306 , a synchronous lens  307 , and a synchronous sensor  308  at an end portion on the writing side in the main scanning direction of the light beam. The light beam scanner  21  has a configuration that the light beam transmitted through the f-θ lens  304  is reflected by the synchronous mirror  306 , is condensed by the synchronous lens  307 , and enters the synchronous sensor  308 . The synchronous sensor  308  functions as a synchronous detection sensor for detecting a synchronous detection signal of determining a writing start timing in the main scanning direction. 
       FIG.  4 A  is a diagram illustrating a configuration of an image forming controller and a light beam scanner disposed in the printer, according to the first embodiment of the present disclosure. Although  FIG.  4 A  illustrates an image forming controller  500  and the light beam scanner  21  for one color, the image forming controller  500  and the light beam scanner  21  are disposed for each color, except for a printer controller  401 , a correction data storage device  402 , and sensors  sr   1  to  sr   5 . 
     The light beam scanner  21  is provided with the synchronous sensor  308  which detects a light beam, at an end portion on the writing side in the main scanning direction of the light beam. The light beam scanner  21  has a configuration that the light beam transmitted through the f-θ lens  304  is reflected by the synchronous mirror  306 , is condensed by the synchronous lens  307 , and enters the synchronous sensor  308 . The light beam passes over the synchronous sensor  308 , thereby to output a synchronous detection signal XDETP from the synchronous sensor  308 . Thus, the synchronous detection signal XDETP is supplied to a pixel clock generator  403 , a synchronous-detection-lighting controller  404 , and a writing-start-position controller  405 . 
     The pixel clock generator  403  generates a pixel clock PCLK synchronized with the synchronous detection signal XDETP and supplies the pixel clock PCLK to the writing-start-position controller  405 , the synchronous-detection-lighting controller  404 , and the printer controller  401 . 
     In order to first detect the synchronous detection signal XDETP, the synchronous-detection-lighting controller  404  turns on an LD forced lighting signal BD to forcibly turn light on the LD unit. On the other hand, after detecting the synchronous detection signal XDETP, the synchronous-detection-lighting controller  404  uses the synchronous detection signal XDETP and the pixel clock PCLK to illuminate the LD unit at a timing at which the synchronous detection signal XDETP can be reliably detected to the extent that flare light is not generated. The synchronous-detection-lighting controller  404  generates the LD forced lighting signal BD that turns off the LD unit when the synchronous detection signal XDETP is detected, and transmits the LD forced lighting signal BD to an LD controller  301 . In addition, the synchronous-detection-lighting controller  404  generates a light amount control timing signal APC of each LD unit using the synchronous detection signal XDETP and the pixel clock PCLK, and transmits the light amount control timing signal APC to the LD controller  301 . This signal needs to be performed outside the image writing area, and the light amount is controlled to a target light amount at above-described timing. 
     The LD controller  301  performs lighting control of the LD unit according to the write data synchronized with the LD forced lighting signal BD, the light amount control timing signal APC, and the pixel clock PCLK. The light beam is emitted from the LD unit, deflected by the polygon mirror  303 , and scanned on the photoconductor drum by the f-θ lens  304  and the return mirror  305 . 
     A polygon motor controller  406  controls the rotation of the polygon motor at a predetermined number of rotations in response to a control signal from the printer controller  401 . The writing-start-position controller  405  generates a main scanning control signal XLGATE and a sub-scanning control signal XFGATE for determining an image writing start timing and an image width based on the synchronous detection signal XDETP, the pixel clock PCLK, and the control signal from the printer controller  401 . 
     The sensors  sr   1  to  sr   3  are an example of a detection device that detects the image pattern (toner image) such as the image misregistration correction pattern or the image density adjustment pattern and sends the detected image pattern to the printer controller  401 . The sensors  sr   1  to  sr   3  are disposed at three positions along a direction intersecting the movement direction of the intermediate transfer belt  10 . The printer controller  401  calculates a misregistration amount and a light amount correction amount based on the detection result of the image pattern and generates correction data such as the misregistration amount and the light amount correction amount. The printer controller  401  sets the generated correction data in the writing-start-position controller  405 , the pixel clock generator  403 , the polygon motor controller  406 , and the LD controller  301 , and stores the generated correction data in the correction data storage device  402 . 
     The sensors  sr   4  to  sr   5  are an example of a detection device that detects the image pattern (toner image) such as the image misregistration correction pattern or the image density adjustment pattern on the recording sheet, and sends the detected image pattern to the printer controller  401 . In addition, the sensors  sr   4  and  sr   5  are disposed at two positions on an end of the recording sheet in a direction intersecting with a conveyance direction of the toner image fixed on the recording sheet as an example of a print medium. The printer controller  401  calculates the misregistration amount and the light amount correction amount based on the detection result of the image pattern, generates the correction data such as the misregistration amount or the light amount correction amount, sets the generated correction data in the writing-start-position controller  405 , the pixel clock generator  403 , the polygon motor controller  406 , and the LD controller  301 , and stores the generated correction data in the correction data storage device  402 . 
     When an image forming operation is performed, the correction data stored is read from the correction data storage device  402  in accordance with an instruction from the printer controller  401 . The correction data is set in the writing-start-position controller  405 , the pixel clock generator  403 , the polygon motor controller  406 , and the LD controller  301 . 
     The printer controller  401  includes a generator of an image pattern such as an image misregistration correction pattern or an image density adjustment pattern, generates an instructed image pattern, and transmits the image pattern to the LD controller  301 . Image data transmitted from a scanner or a personal computer (PC) undergo signal processing in the printer controller  401  and are transmitted to the LD controller  301 . 
       FIG.  4 B  is a diagram illustrating a hardware configuration of the printer controller of the color image forming apparatus, according to the first embodiment of the present disclosure. As illustrated in  FIG.  4 B , the printer controller  401  includes a central processing unit (CPU)  241 , a read only memory (ROM)  242 , a random access memory (RAM)  243 , and an input/output (I/O) port  244 . 
     The CPU  241  is an arithmetic device that sequentially executes, e.g., branching processing or iterative processing by executing a program stored in the ROM  242 . The ROM  242  is a non-volatile storage device in which a program executed in the CPU  241  is stored. The RAM  243  is a memory that functions as a work area (working area) for the operation of the CPU  241 . 
     A bus line  245  is, e.g., an address bus or a data bus to electrically connect the components such as the CPU  241 . The I/O port  244  is an interface to which various signals such as signals output from the sensor  sr   1 , the sensor  sr   2 , the sensor  sr   3 , the sensor  sr   4 , and the sensor  sr   5  are input and from which various signals are output. The hardware configuration of the printer controller  401  is not limited to the above-described hardware configuration and may be any other hardware configuration that can implement the function of the printer controller  401  described above. 
     The LD controller  301 , the pixel clock generator  403 , the synchronous-detection-lighting controller  404 , the writing start position controller  405 , and the polygon motor controller  406  may be configured by an application specific integrated circuit (ASIC). The LD controller  301 , the pixel clock generator  403 , the synchronous-detection-lighting controller  404 , the writing start position controller  405 , and the polygon motor controller  406  may be configured by a single ASIC or a plurality of ASICs. The LD controller  301 , the pixel clock generator  403 , the synchronous-detection-lighting controller  404 , the writing start position controller  405 , and the polygon motor controller  406  may be implemented by a hardware configuration similar to the hardware configuration implementing the printer controller  401 . The correction data storage device  402  may be implemented by a non-volatile storage medium such as a hard disk drive (HDD). 
       FIG.  5    is diagram illustrating a functional configuration of a reference clock generator and a voltage-controlled oscillator (VCO) clock generator in a pixel clock generator disposed in the printer, according to the first embodiment of the present disclosure. A reference clock generator  403   a  generates a reference clock signal FREF. A VCO clock generator  403   b  inputs the reference clock signal FREF from the reference clock generator  403   a  and a signal obtained by N-dividing the VCLK by a 1/N frequency divider  501  to a phase comparator  502 . 
     The phase comparator  502  compares the phases of the falling edges of both signals and outputs an error component as a constant current. Then, the VCO clock generator  403   b  removes unnecessary high-frequency components and noise included in the constant current output from the phase comparator  502  by a low pass filter (LPF)  503  and transmits the constant current to a VCO  504 . The VCO  504  outputs an oscillation frequency depending on the output of the LPF  503 . 
     Accordingly, the VCO clock generator  403   b  can vary the frequency of the VCLK by varying the frequency of the reference clock signal FREF and the frequency division ratio “N” in the 1/N frequency divider  501  from the printer controller  401 . As the frequency of the VCLK changes, the frequency of the pixel clock PCLK also changes. For example, the frequency of the pixel clock PCLK is slowed down to increment the image magnification in the main scanning direction. 
       FIG.  6    is a diagram illustrating a functional configuration of the writing-start-position controller  405  disposed in the printer, according to the first embodiment of the present disclosure. The writing-start-position controller  405  includes a main-scanning-line synchronous signal generator  405   a , a main scanning gate signal generator  405   b , and a sub-scanning gate signal generator  405   c . 
     The main-scanning-line synchronous signal generator  405   a  generates an XLSYNC signal for operating a main scanning counter  601  in the main scanning gate signal generator  405   b  and a sub-scanning counter  611  in the sub-scanning gate signal generator  405   c . The main scanning gate signal generator  405   b  generates an XLGATE signal for determining the timing of capturing an image signal (timing of writing out an image in the main scanning direction). The sub-scanning gate signal generator  405   c  generates an XFGATE signal for determining the timing of capturing an image signal (timing of writing out an image in the sub-scanning direction). 
     The main scanning gate signal generator  405   b  includes the main scanning counter  601 , a comparator  602 , and a gate signal generator  603 . The main scanning counter  601  operates with XLSYNC and PCLK. The comparator  602  compares the counter value of the main scanning counter  601  with a set value  1  (correction data) from the printer controller  401  and outputs the result. A gate signal generator  603  generates the XLGATE from the comparison result from the comparator  602 . 
     The sub-scanning gate signal generator  405   c  includes a sub-scanning counter  611 , a comparator  612 , and a gate signal generator  613 . The sub-scanning counter  611  operates based on the control signal (a print start signal) from the printer controller  401 , the XLSYNC, and the PCLK. The comparator  612  compares the counter value of the sub-scanning counter  611  with a set value  2  (correction data) from the printer controller  401  and outputs the result. The gate signal generator  613  generates the XFGATE from the comparison result from the comparator  612 . 
     The writing-start-position controller  405  corrects the writing position in the main scanning direction in units of one cycle of the PCLK, that is, in units of one dot of the pixel clock PCLK, and corrects the writing position in the sub-scanning direction in units of one cycle of the XLSYNC, that is, in units of one line of the XLSYNC. The correction data is stored in the correction data storage device  402  with respect to the main-scanning direction and sub-scanning direction. 
       FIG.  7    is a timing chart of control processing of a writing-start-position in a main scanning direction by the writing-start-position controller disposed in the printer, according to the first embodiment of the present disclosure. In the writing-start-position controller  405 , the main scanning counter  601  is reset by XLSYNC, and the counter value is counted up by PCLK. When the counter value reaches the set value  1  (for example, X) set by the printer controller  401 , the comparison result is output from the comparator  602 , and XLGATE is set to Low level (valid) by the gate signal generator  603 . The XLGATE is a signal lowered in level for an image width in the main scanning direction. 
       FIG.  8    is a timing chart of control processing of a writing start position in a sub-scanning direction by the writing-start-position controller disposed in the printer, according to the first embodiment of the present disclosure. In the writing-start-position controller  405 , the sub-scanning counter  611  is reset by a print start signal from the printer controller  401 , and the counter value is counted up by XLSYNC. When the counter value reaches the set value  2  (for example, Y) set by the printer controller  401 , the comparison result is output from the comparator  612 , and XFGATE is set to Low level (valid) by the gate signal generator  603 . The XFGATE is a signal lowered in level for an image length in the sub-scanning direction. 
       FIG.  9    is a diagram illustrating a functional configuration of a printer controller disposed in the printer, according to the first embodiment of the present disclosure. The printer controller  401  generates image patterns that include, for example, an image misregistration correction pattern, an image density adjustment pattern, or a test chart for checking the state of the image forming apparatus. In the present embodiment, the printer controller  401  includes a first pattern generator  901  to a fifth pattern generator  905  that generate image patterns different from each other. That is, the printer controller  401  can generate five types of image patterns. The image patterns generated by each of the pattern generators from the first pattern generator  901  to the fifth pattern generator  905  are output to a reverse unit  906 . 
     The reverse unit  906  can select whether to reverse the image pattern. The reverse unit  906  reverses the black and white of the input image pattern and outputs the reversed image pattern to a first pattern synthesizer  907  in a case where the black and white of the image pattern is reversed. On the other hand, the reverse unit  906  outputs the image pattern as it is to the first pattern synthesizer  907  in a case where the black and white of the image pattern is not reversed. That is, the reverse unit  906  reverses black and white of at least one of the image patterns when two or more types of image patterns are combined. As a result, the number of types of image patterns can be easily increased. 
     The first pattern synthesizer  907  synthesizes the image patterns and outputs the synthesized image pattern to a pattern processing unit  908 . That is, the first pattern generator  901  to the fifth pattern generator  905 , the reverse unit  906 , and the first pattern synthesizer  907  function as an example of a patch-image-data generator  900  that generates an image pattern in which two or more types of image patterns (an example of a patch image) are combined. In the present embodiment, a combination of patch images of different colors may be used. 
     The pattern processing unit  908  is an example of a patch-image-data changing unit that changes image data around at least one image pattern to be less than the maximum value when two or more types of patch images are combined. As a result, when a pattern image other than a predetermined pattern image is generated, the number of types of pattern images that can be generated can be increased without adding any new pattern generation function. When a plurality of preset image patterns are simultaneously generated in order to increase the number of types of image patterns, an incident in which the image patterns cannot be recognized due to superimposing of the image patterns can be prevented. 
     That is, when two or more image patterns are synthesized, the pattern processing unit  908  changes the image data of the boundary if the boundary is unclear and the image pattern cannot be recognized. For example, when the image data of the boundary is the same two hundred fifty fifth gradation, the pattern processing unit  908  changes the image data of the boundary to the zeroth to two hundred fifty fourth gradations. More preferably, the pattern processing unit  908  changes the image data of the boundary to the one hundred twenty eighth gradation corresponding to ½ or zero. 
     A second pattern synthesizer  909  synthesizes the image data to be printed and the patterns generated by the first pattern generator  901  to the fifth pattern generator  905 . For example, the second pattern synthesizer  909  adds patterns to four corners of image data to be printed, detects an image misregistration, and outputs an image while correcting the image misregistration. The second pattern synthesizer  909  sends the synthesized pattern to the LD controller  301  and controls lighting of the LD unit according to the write data. 
       FIG.  10    is a flowchart of control processing of an LD unit performed by the image forming apparatus, according to the first embodiment of the present disclosure. First, the printer controller  401  causes the polygon motor controller  406  to rotate the polygon motor at a predetermined number of rotations per unit time (in step S 1001  of  FIG.  10   ). 
     The printer controller  401  sets the correction data (for example, the writing start position in the main scanning direction, the writing start position in the sub-scanning direction, and the set value of the magnification) stored in the correction data storage device  402  to each controller (for example, the writing-start-position controller  405 , the pixel clock generator  403 , the polygon motor controller  406 , and the LD controller  301 ) (in step S 1002  of  FIG.  10   ). The printer controller  401  illuminates the LD unit (in step S 1003  of  FIG.  10   ) to output the synchronous detection signal and performs an APC operation to prepare for turning on each LD unit with a specified amount of light. 
     Thereafter, the patch-image-data generator  900  of the printer controller  401  selects an image pattern to be generated (in step S 1004  of  FIG.  10   ), synthesizes the selected image patterns (in step S 1005  of  FIG.  10   ), and forms the image pattern (in step S 1006  of  FIG.  10   ). 
     The patch-image-data generator  900  of the printer controller  401  determines whether there is any next image pattern to be formed (in step S 1007  of  FIG.  10   ). If there is a next image pattern to be formed (YES in step S 1007  of  FIG.  10   ), the printer controller  401  repeats the processing of steps S 1004  to S 1006  in  FIG.  10   . On the other hand, if there is no image pattern to be formed next (NO in step S 1007  of  FIG.  10   ), the printer controller  401  turns off each LD unit (in step S  1008  of  FIG.  10   ), stops the polygon motor, and ends the process (in step S 1009  of  FIG.  10   ). 
       FIG.  11    is a diagram illustrating the image pattern to be formed on the intermediate transfer belt, and a sensor, in the image forming apparatus, according to the first embodiment of the present disclosure. An image pattern P 1  generated by the first pattern generator  901  is an image pattern for detecting the image density using the sensors  sr   1  and  sr   2 . The sensors  sr   1  and  sr   2  are an example of a detection device that can detect an image pattern in the vicinity of both end portions of the intermediate transfer belt  10  in the main scanning direction. 
     An image pattern P 2  generated by a second pattern generator  902  is an image pattern for detecting the image misregistration using the sensors  sr   1  and  sr   2 . An image pattern P 3  generated by a third pattern generator  903  is an image pattern for detecting the image density using the sensors  sr   1  to  sr   3 . A sensor  sr   3  is an example of a detection device that can detect an image pattern in the vicinity of the central portion of the intermediate transfer belt  10  in the main scanning direction. 
       FIG.  12    is a diagram illustrating an example of a sensor and a synthesized image pattern formed on the intermediate transfer belt by the image forming apparatus according to the first embodiment. For example, the image pattern P 1  is generated by the first pattern generator  901 , is reversed (for example, black and white reversing) by the reverse unit  906 , and is transmitted to the first pattern synthesizer  907 . At the same time, the image pattern P 2  is generated by the second pattern generator  902 , and is sent to the first pattern synthesizer  907  without being reversed by the reverse unit  906 . The first pattern synthesizer  907  can generate an image pattern P 12  illustrated in  FIG.  12    by synthesizing the two image patterns P 1  and P 2 . By using the image pattern P 12 , the image position can be detected by the sensors  sr   1  and  sr   2 , and the image density can be detected by the sensor  sr   3 . 
       FIG.  13    is a diagram illustrating a synthesized image pattern formed on the intermediate transfer belt by the image forming apparatus, and a sensor, according to the first embodiment of the present disclosure. For example, the second pattern generator  902  generates the image pattern P 2  and transmits the image pattern P 2  to the first pattern synthesizer  907 . At the same time, the third pattern generator  903  generates the image pattern P 3  and sends the image pattern P 3  to the first pattern synthesizer  907 . After the image pattern P 2  and the image pattern P 3  are synthesized by the first pattern synthesizer  907  to generate an image pattern P 23 , the pattern processing unit  908  deletes the peripheral dots of the image pattern P 2  in the image pattern P 23 , that is, sets the peripheral dots of the image pattern P 2  to zero. As a result, the image position can be detected by the sensors  sr   1  and  sr   2 , and at the same time, the image density can also be detected by the sensor  sr   3 . 
       FIG.  14    is a diagram illustrating an image pattern to be formed on a recording sheet by the image forming apparatus, and a position of a sensor, according to the first embodiment of the present disclosure. An image pattern P 4  generated by the fourth pattern generator  904  is an image pattern for detecting the image density using the sensors  sr   4  and  sr   5 . The sensors  sr   4  and  sr   5  are an example of a detection device that can detect image patterns in the vicinity of both ends of the recording sheet in the main scanning direction. In the present embodiment, the sensors  sr   4  and  sr   5  are disposed downstream from the fixing device in the conveyance direction of the recording sheet. An image pattern P 5  generated by the fifth pattern generator  905  is an image pattern for detecting the image misregistration on the recording sheet using the sensors  sr   4  and  sr   5 . 
       FIG.  15    is a diagram illustrating a synthesized image pattern formed on the recording sheet by the printer, and a position of a sensor, according to the first embodiment of the present disclosure. For example, when the image pattern P 4  is generated by the fourth pattern generator  904 , the reverse unit  906  reverses the image pattern P 4  and sends the reversed image pattern P 4  to the first pattern synthesizer  907 . At the same time, when the image pattern P 5  is generated by the fifth pattern generator  905 , the reverse unit  906  sends the image pattern P 5  to the first pattern synthesizer  907  without reversing the image pattern P 5 . 
     Next, the first pattern synthesizer  907  synthesizes the two image patterns P 4  and P 5  to generate an image pattern P 45  illustrated in  FIG.  15   . By using the image pattern P 45 , unlike the image pattern P 5 , the image position can be detected in a state in which the image pattern P 45  is printed on the recording sheet. By comparing with the image misregistration of the image pattern P 5 , the influence of the presence or absence of the image pattern on the image misregistration can be found. 
     The image forming apparatus according to the present embodiment generates, for example, the image pattern P 4  in magenta and the image pattern P 5  in black. When the above-described process is executed, the image forming apparatus can detect the image position of the color image in a state in which the magenta image pattern P 4  is printed on the recording sheet. When the same image pattern is generated in two colors in the image pattern P 4 , the image position can be detected in a state in which the image pattern in which two colors are superimposed is printed on the recording sheet. That is, the image pattern may be a combination of image patterns of different colors. As a result, the number of types of image patterns can be increased. 
     As described above, according to the image forming apparatus of the first embodiment, when a pattern image other than a predetermined pattern image is generated, the number of types of pattern images that can be generated can be increased without adding a new pattern generation function. When a plurality of preset image patterns are simultaneously generated in order to increase the number of types of image patterns, an incident in which the image patterns cannot be recognized due to superimposing of the image patterns can be prevented. 
     Second Embodiment 
     A second embodiment is an example in which an image pattern transferred to a secondary transfer belt is detected. In the following description, the description of the same components as those of the first embodiment is omitted. 
       FIG.  16    is a diagram illustrating a configuration of an image forming device disposed in an image forming apparatus according to the second embodiment of the present disclosure. In the second embodiment, the image forming device  20  includes, in addition to the intermediate transfer belt  10  (an example of a first transfer belt), a secondary transfer belt  24  (an example of a second transfer belt) to contact the intermediate transfer belt  10 . 
     The secondary transfer unit  22  of the image forming device  20  transfers an image pattern (correction pattern) formed on the intermediate transfer belt  10  onto the secondary transfer belt  24 . Sensors  sr   6  to  sr   8  are reflection-type optical sensors and detect an image pattern formed on the secondary transfer belt  24 . The sensors  sr   6  to  sr   8  supply the detected image pattern to the printer controller  401 . The printer controller  401  calculates an image misregistration of an image pattern (an image pattern formed on the secondary transfer belt  24  in the second embodiment) and generates correction data for correcting the image misregistration in the same manner as in the above-described first embodiment. 
     This correction data is set in the writing-start-position controller  405  and the pixel clock generator  403 , and is stored in the correction data storage device  402 . When an image forming operation is performed, the correction data stored in the correction data storage device  402  is read by the printer controller  401 , which is an example of a correction unit, and is set in the writing-start-position controller  405  and the pixel clock generator  403 . The image pattern having passed through the sensors  sr   6  to  sr   8  is removed by a secondary transfer belt cleaner  70 . The description of the image pattern transferred to the secondary transfer belt  24  is omitted, because the secondary transfer belt  24  is interchangeable with the intermediate transfer belt  10  in  FIGS.  11  to  13   . The sensors  sr   6  to  sr   8  may have the same configurations as the sensors  sr   1  to  sr   3  illustrated in  FIGS.  11  to  13   . 
     As described above, according to the printer  100  of the second embodiment, even when the image pattern transferred to the secondary transfer belt  24  is detected, the same functional effect as those of the first embodiment can be obtained. 
     Third Embodiment 
     In an inkjet printer of a third embodiment of the present disclosure, an image pattern is generated by combining two or more types of patch images. When the two or more types of patch images are combined, image data around at least one of patch images is changed to less than the maximum value. In the following description, a description of the same configuration as the description of above-described embodiment is omitted. 
       FIG.  17    is a diagram illustrating a schematic configuration of an inkjet recording apparatus according to the third embodiment of the present disclosure. As illustrated in  FIG.  17   , an inkjet recording apparatus  1000  includes a sheet feeder  1100 , an image forming device  1200 , a drying device  1300 , and a sheet ejection device  1400 . In the inkjet recording apparatus  1000 , the image forming device  1200  forms an image on a sheet P with ink, which is an example of liquid for image formation, on the sheet P as an example of a recording medium as a sheet material fed from the sheet feeder  1100 . The inkjet recording apparatus  1000  ejects the sheet P through the sheet ejection device  1400  after the drying device  1300  dries the ink applied onto the sheet P. 
     First, a description is given of the sheet feeder  1100 . 
     The sheet feeder  1100  mainly includes a sheet feeding tray  1110  on which a plurality of sheets P are stacked, a feeding device  1120  that separates and feeds the sheets P one by one from the sheet feeding tray  1110 , and a registration roller pair  1130  that feeds the sheets P to the image forming device  1200 . 
     The feeding device  1120  may be a feeding device that includes rollers, a feeding device employing an air suction method, and any other feeding devices. 
     The sheet feeder  1100  drives the registration roller pair  1130  at a specified timing after the leading end of the sheet P fed from the sheet feeding tray  1110  by the feeding device  1120  has reached the registration roller pair  1130 . Thus, the sheet P is fed to the image forming device  1200 . 
     In the present embodiment, the configuration of the sheet feeder  1100  is not limited to any particular configuration and may be any configuration as long as the sheet feeder  1100  can feed the sheet P to the image forming device  1200 . 
     Next, a description is given of the image forming device  1200 . 
     The image forming device  1200  mainly includes a receiving cylinder  1201 , a sheet carrying drum  1210 , an ink discharge device  1220 , and a delivery cylinder  1202 . The receiving cylinder  1201  receives the sheet P fed from the registration roller pair  1130 . The sheet carrying drum  1210 , which functions as a conveying unit, conveys the sheet P conveyed by the receiving cylinder  1201  while carrying the sheet P on an outer circumferential surface of the sheet carrying drum  1210 . The ink discharge device  1220  discharges ink toward the sheet P carried on the sheet carrying drum  1210 . The delivery cylinder  1202  delivers the sheet P conveyed by the sheet carrying drum  1210  to the drying device  1300 . 
     The leading end of the sheet P conveyed from the sheet feeder  1100  to the image forming device  1200  is gripped by a sheet gripper disposed on the surface of the receiving cylinder  1201 . The sheet P is conveyed along with the movement of the surface of the receiving cylinder  1201 . The sheet P conveyed by the receiving cylinder  1201  is delivered to the sheet carrying drum  1210  at a position facing the sheet carrying drum  1210 . 
     A sheet gripper is also disposed on the surface of the sheet carrying drum  1210 , and the leading end of the sheet P is gripped by the sheet gripper. Multiple suction holes are dispersedly formed on the surface of the sheet carrying drum  1210 . A suction device  1211  generates a suction air flow toward the inside of the sheet carrying drum  1210  in each suction hole. 
     The leading end of the sheet P delivered from the receiving cylinder  1201  to the sheet carrying drum  1210  is gripped by the sheet gripper. The sheet P is sucked onto the surface of the sheet carrying drum  1210  by the suction air flow and is conveyed along with the movement of the surface of the sheet carrying drum  1210 . 
     The ink discharge device  1220  in the present embodiment is a line-head device that discharges ink of four colors of C (cyan), M (magenta), Y (yellow), and K (black) to form an image and includes individual liquid discharge heads  1220 C,  1220 M,  1220 Y, and  1220 K for ink of the four colors. 
     The configuration of the liquid discharge heads  1220 C,  1220 M,  1220 Y, and  1220 K is not limited to any particular configuration and may be any configuration that can discharge. In some embodiments, the liquid discharge device may include a liquid discharge head that discharges special ink such as white, gold, and silver or a liquid discharge head that discharges a surface coating liquid that does not form an image. 
     Discharge operations of the liquid discharge heads  1220 C,  1220 M,  1220 Y, and  1220 K of the ink discharge device  1220  are controlled by drive signals corresponding to image information. When the sheet P carried on the sheet carrying drum  1210  passes through a region facing the ink discharge unit  1220 , color inks are discharged from the liquid discharge heads  1220 C,  1220 M,  1220 Y, and  1220 K to form an image corresponding to the image information. 
     In the present embodiment, the configuration of the image forming device  1200  is not limited to any particular configuration as long as an image is formed by applying liquid onto the sheet P. 
     In addition, as illustrated in  FIG.  17   , the image forming device  1200  is provided with two scanners  1231  and  1232 , which are line scanners, downstream from the ink discharge device  1220  in the conveyance direction of the sheet P. The two scanners  1231  and  1232  are image readers that read the image patterns. The resolutions of the two scanners  1231  and  1232  are lower than the print resolution in the image forming device  1200 . 
     The image forming device  1200  prints an image pattern by the ink discharge device  1220  in a state where the sheet P is attracted by suction on the surface of the sheet carrying drum  1210  and conveyed with the leading end of the sheet P being gripped by the sheet gripper. Immediately after the printing, the two scanners  1231  and  1232  read the image pattern. 
       FIG.  18    is a diagram illustrating an arrangement of two scanners disposed in the inkjet recording apparatus according to the third embodiment of the present disclosure. As illustrated in  FIG.  18   , the two scanners, i.e., the scanner (front)  1231  and the scanner (rear)  1232 , are arranged in a staggered manner to read the entire surface of the sheet P. More specifically, the two scanners  1231  and  1232  have a region (overlapped region) in which the reading ranges overlap each other in the main scanning direction. The two scanners  1231  and  1232  are arranged offset from each other in the sub-scanning direction. In the present embodiment, the scanners  1231  and  1232  functions as an example of a detection device. 
     Although the two scanners  1231  and  1232  are disposed in the present embodiment, the configuration is not limited thereto. A single scanner or a combination of three or more scanners may be used as long as the reading range in the main scanning direction can be secured. 
     Next, a description is given of the drying device  1300 . 
     As illustrated in  FIG.  17   , the drying device  1300  includes a drying mechanism  1301  and a conveying mechanism  1302 . The drying mechanism  421  dries ink adhered to the sheet P in the image forming device  1200 . A conveying mechanism  422  conveys a sheet P conveyed from the image forming device  1200 . 
     The sheet P conveyed from the image forming device  1200  is received by the conveying mechanism  1302 , conveyed to pass through the drying mechanism  1301 , and delivered to the sheet ejection device  1400 . When the sheet P passes through the drying mechanism  1301 , the drying device  1300  dries ink on the sheet P. As a result, liquid components such as moisture in the ink are evaporated, the ink is fixed on the sheet P, and curling of the sheet P is prevented. 
     Next, a description is given of the sheet ejection device  1400 . 
     The sheet ejection device  1400  includes a sheet ejection tray  1410  on which a plurality of sheets P are stacked. The sheets P conveyed from the drying device  1300  are sequentially stacked and held on the sheet ejection tray  1410 . 
     In the present embodiment, the configuration of the sheet ejection device  1400  is not limited to any particular configuration and may be any configuration that can receive ejected sheets P. 
     Next, a description is given of other functional devices. 
     The inkjet recording apparatus  1000  according to the present embodiment includes the sheet feeder  1100 , the image forming device  1200 , the drying device  1300 , and the sheet ejection device  1400 . However, other functional devices may be added as appropriate. For example, a pre-processing device that performs pre-processing of image formation may be added between the sheet feeder  1100  and the image forming device  1200 . Alternatively, a post-processing device that performs post-processing of image formation may be added between the drying device  1300  and the sheet ejection device  1400 . 
     An example of the pre-processing device performs a processing liquid applying operation to apply processing liquid onto the sheet P so as to reduce bleeding by reacting with ink. However, the content of the pre-processing operation is not limited to any particular processing. Examples of the post-processing device include a sheet reversing-and-conveying process for reversing a sheet on which an image has been formed by the image forming device  1200  and sending the sheet to the image forming device  1200  again to form images on both sides of the sheet, a process for binding a plurality of sheets on which images have been formed, a correction mechanism that corrects sheet deformation, and a cooling mechanism that cools the sheet. 
     Next, a description is given of a control configuration of an inkjet recording apparatus  1 . 
       FIG.  19    is a block diagram illustrating a control configuration of an inkjet recording apparatus according to the third embodiment of the present disclosure. As illustrated in  FIG.  19   , the inkjet recording apparatus  1  includes a controller  1910  that controls the entire apparatus. The controller  1910  includes a central processing unit (CPU)  1911  serving as a main controller, a read only memory (ROM)  1912 , a random access memory (RAM)  1913 , a memory  1914 , and an application specific integrated circuit (ASIC)  1915 . The ROM  1912  stores a computer program executed by the CPU  1911  and other fixed data. The RAM  1913  temporarily stores, e.g., image data. The memory  1914  is a rewritable nonvolatile memory for holding data even while a power supply of the inkjet recording apparatus  1000  is cut off. The ASIC  1915  performs various types of signal processing on image data, image processing such as sorting, and other input/output signal processing to control the entire apparatus. 
     As illustrated in  FIG.  19   , the controller  1910  includes a host interface (I/F)  1916 , a head drive controller  1917 , a motor controller  1918 , an I/O  1919 , and a scanner controller  1908 . 
     The host I/F  1916  according to the present embodiment sends and receives image data (print data) to and from the host device via a cable or a network. Examples of the host device connected to the inkjet recording apparatus  1  include an information processing apparatus such as a personal computer (PC), an image reading apparatus such as an image scanner, and an imaging apparatus such as a digital camera. 
     The I/O  1919  connects various sensors  1925  such as moisture sensors, temperature sensors, and other sensors. The I/O  1919  inputs detection signals from the various sensors  1925 . 
     The head drive controller  1917  controls to drive the ink discharge device  1220  and includes a data transmitter. More specifically, the head drive controller  1917  transfers the image data as serial data. The head drive controller  1917  generates a transfer clock and a latch signal which are necessary for, e.g., transmission of image data, determination of the transmission, and a drive waveform which is used when droplets are discharged from the ink discharge device  1220 . The head drive controller  1917  inputs the generated drive waveform to a drive circuit inside the ink discharge device  1220 . 
     The motor controller  1918  drives a motor M for rotating, e.g., the receiving cylinder  1201 , the sheet carrying drum  1210 , or the delivery cylinder  1202 . 
     The scanner controller  1908  controls the two scanners  1231  and  1232 . 
     In addition, the controller  1910  is connected to an operation panel  1960  for inputting and displaying information necessary for the inkjet recording apparatus  1 . 
     The controller  1910  comprehensively controls each unit by deploying a computer program read by the CPU  1911  from the ROM  1912  (or memory  1914 ) to the RAM  1913  to execute the computer program. More specifically, the CPU  1911  reads out the control content set for each print mode from the ROM1912 (or memory  1914 ) based on the print mode set from the operation panel  1960 . The CPU  1911  controls each unit based on the control content read from the ROM1912 (or memory  1914 ), thereby performing the control described below. 
     The computer program to be executed by the inkjet recording apparatus  1000  according to the present embodiment may be provided to be recorded in any desired computer-readable recording medium such as a compact disc, a compact disc-read only memory (CD-ROM), a flexible disk (FD), a compact disc-recordable (CD-R), and a digital versatile disk (DVD) in a file format installable or executable. 
     A computer program to be executed by the inkjet recording apparatus  1000  according to the present embodiment may be stored in a computer connected to a network such as the Internet, and may be provided to be downloaded via the network. Such a computer program to be executed by, e.g., the inkjet recording apparatus  1000  according to the present embodiment may be provided or distributed via a network such as the Internet. 
     The computer program to be executed by the inkjet recording apparatus  1000  according to the present embodiment may be provided by being incorporated in, e.g., a ROM in advance. 
     In the present embodiment, the controller  1910  functions as an example of the patch-image-data generator  900  and the pattern processing unit  908 . 
     Note that in the present embodiment as described above, the image forming apparatus according to the present disclosure is applied to a multifunction printer or multifunction peripheral (MFP) that has at least two of a photocopying function, a printing function, a scanning function, and a facsimile (FAX) function. However, no limitation is intended thereby, and the image forming apparatus according to the present disclosure may be applied to any image forming apparatus such as a copier, a printer, a scanner, and a facsimile. 
     Each of the functions of the above-described embodiments may be implemented by one or more processing circuits or circuitry. The “processing circuit” in the present specification includes a central processing unit (CPU) programmed to execute each function by software like a processor implemented by an electronic circuit, and a device such as an application specific integrated circuit (ASIC), a digital signal processor (DSP), a field programmable gate array (FPGA), or a conventional circuit module designed to execute each function described above. For example, the polygon motor controller  406 , the writing start position controller  405 , the LD controller  301 , the synchronous-detection-lighting controller  404 , the pixel clock generator  403 , and the printer controller  401  can be implemented by one or a plurality of processing circuits. A plurality of controllers may be configured in one processing circuit. 
     Numerous additional modifications and variations are possible in light of the above teachings. It is therefore to be understood that, within the scope of the above teachings, the present disclosure may be practiced otherwise than as specifically described herein. With some embodiments having thus been described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the scope of the present disclosure and appended claims, and all such modifications are intended to be included within the scope of the present disclosure and appended claims. 
     Any one of the above-described operations may be performed in various other ways, for example, in an order different from the one described above. 
     Each of the functions of the described embodiments may be implemented by one or more processing circuits or circuitry. Processing circuitry includes a programmed processor, as a processor includes circuitry. A processing circuit also includes devices such as an application specific integrated circuit (ASIC), a digital signal processor (DSP), a field programmable gate array (FPGA), and conventional circuit components arranged to perform the recited functions.