JP2015161938A - Image forming apparatus, image forming system, formation position correction program, and formation position correction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct a position to form an image relative to a sheet with at least one of a configuration different from the conventional one and a configuration obtained by improving the conventional one.SOLUTION: In a compound machine 1, when a position to form an image relative to a sheet W is displaced, the number of marks M1 and M2 changes, which are on the sheet W having patterns P1 and P2 formed thereon. The position to form an image relative to the sheet W is corrected on the basis of mark information on the number of the marks M1 and M2. Thus, the position to form an image relative to the sheet W can be corrected with at least one of a configuration different from the conventional one and a configuration obtained by improving the conventional one.

Description

  The present invention relates to a technique for correcting an image forming position on a sheet.

  Conventionally, there is an image forming apparatus that corrects an image forming position on a sheet (see Patent Document 1). This image forming apparatus forms a square mark so as to protrude from the sheet with respect to each side of the sheet, and then reads the sheet after the mark is formed by a reading unit. The size of each mark and the distance between the marks are calculated, and the image formation position on the sheet is corrected based on the calculation result.

JP 2006-91329 A

  However, in the conventional image forming apparatus, it is essential to calculate the size of each mark on the sheet and the distance between the marks, and improvement has been desired.

  The present specification discloses a technique capable of correcting an image forming position on a sheet with at least one of a configuration different from the conventional configuration and a configuration obtained by improving the conventional configuration.

  An image forming apparatus disclosed in this specification includes an image forming unit, an acquisition unit, and a control unit, and the control unit applies a pattern having a plurality of marks to the image forming unit in a main scanning direction. And a pattern forming process that is formed at a position straddling the side of the sheet in at least one of the sub-scanning directions, wherein the plurality of marks are different from each other in the position of the sheet side end in the one direction. Forming an image on a sheet based on a forming process, an acquiring process in which the acquiring unit acquires mark information according to the number of marks on the sheet on which the pattern is formed, and the mark information acquired in the acquiring process; And a correction process for correcting the position.

  According to this image forming apparatus, when the image forming position on the sheet is shifted, the number of marks on the sheet on which the pattern is formed is different. Then, the image formation position on the sheet is corrected based on the mark information regarding the number of marks. Accordingly, the image forming position on the sheet can be corrected by at least one of a configuration different from the conventional configuration and a configuration obtained by improving the conventional configuration.

  In the image forming apparatus, each of the marks may have a bar shape along the one direction. According to this image forming apparatus, the visibility of the number of marks on a sheet on which a pattern is formed can be improved as compared with a case where each mark has a dot shape, for example.

  In the image forming apparatus, the plurality of marks may have a longer length in the one direction as a mark whose end on the sheet side is closer to a side facing the side across the pattern.

  According to this image forming apparatus, it is possible to save the amount of colorant used for mark formation while improving the visibility as compared with the case where all the marks have the same length in one direction. it can.

  The image forming apparatus includes a conveyance unit, the acquisition unit is a reading unit, the control unit conveys the sheet on which the pattern is formed to the conveyance unit, and the reading unit. A reading process for reading a mark on a sheet conveyed by the conveyance unit, and the pattern includes a plurality of marks straddling a side of the sheet in the main scanning direction. They are arranged at intervals in the sub-scanning direction, and the intervals may be equal to or longer than the sheet conveyance distance of the conveyance unit within the reading line period of the reading unit.

  According to this image forming apparatus, compared with a configuration in which the interval between marks is less than the sheet conveying distance of the conveying unit within the reading line period, the reading unit can suppress reading out the marks on the sheet. it can.

  The image forming apparatus includes a conveyance unit, the acquisition unit is a reading unit, the control unit conveys the sheet on which the pattern is formed to the conveyance unit, and the reading unit. A reading process for reading a mark on a sheet conveyed by the conveyance unit, the pattern straddling a side of the sheet in the sub-scanning direction, and the plurality of marks being spaced apart in the main scanning direction. The distances in the sub-scanning direction between the edges of the marks on the sheet side may be equal to or greater than the sheet conveying distance of the conveying unit within the reading line period of the reading unit.

  According to this image forming apparatus, the reading unit reads out the mark on the sheet compared to a configuration in which the distance between the sheet-side ends of each mark is less than the sheet conveying distance of the conveying unit within the reading line cycle. This can be suppressed.

  In the image forming apparatus, the image forming unit includes a plurality of process units that form images with colorants having different colors, and the control unit performs the pattern forming process and the acquisition for each of the plurality of process units. Processing and correction processing may be executed.

  According to this image forming apparatus, the image forming position on the sheet can be corrected for each process.

  In the image forming apparatus, the plurality of process units include two process units that use colorants having different visibility from each other, and the control unit performs visibility of the two process units in the pattern forming process. The process portion using a low colorant may have a higher image density when forming the mark than the process portion using a colorant with high visibility.

  According to this image forming apparatus, each mark can be formed with an appropriate image density as compared with the configuration in which the image density is the same regardless of the visibility of the colorant.

  In the image forming apparatus, the colorant having low visibility may be yellow, and the colorant having high visibility may be black.

  According to this image forming apparatus, it is possible to form a yellow mark with an appropriate image density as compared with a configuration in which the image density is the same regardless of the visibility of the colorant.

  In the image forming apparatus, the control unit forms a plurality of the patterns on the same side of the sheet in the pattern forming process, and marks the patterns based on the mark information acquired in the acquiring process. An error is notified in accordance with a determination process for determining whether or not the difference in the number of patterns is equal to or greater than a specified number, and in the determination process that the difference in the number of marks between the patterns is determined to be equal to or greater than a specified number Notification processing to be performed may be executed.

  According to this image forming apparatus, it is possible to notify the outside that an abnormality such as the sheet being greatly inclined has occurred.

  In the image forming apparatus, the control unit forms a plurality of the patterns on the same side of the sheet in the pattern forming process, and marks the patterns based on the mark information acquired in the acquiring process. A determination process is performed to determine whether or not the difference in the number is equal to or greater than a specified number, and the determination process determines that the difference in the number of marks between the patterns is less than a specified number. Correction processing may be executed.

  According to this image forming apparatus, it is possible to prevent the correction processing from being performed in vain in a state where an abnormality such as the sheet being greatly inclined is generated.

  The image forming system includes an image forming apparatus and a reading device, the image forming apparatus includes an image forming unit and an image control unit, and the reading device includes a reading unit and a reading control unit. The image control unit is a pattern forming process that causes the image forming unit to form a pattern having a plurality of marks at a position straddling the side of the sheet in at least one of the main scanning direction and the sub-scanning direction. The plurality of marks execute a pattern forming process in which positions of edges on the sheet side in the one direction are different from each other, and the reading control unit causes the reading unit to mark on the sheet after the pattern forming process The image control unit is configured to read a number of marks on the sheet on which the pattern is formed based on a reading result of the reading process in the reading device. An acquisition process for acquiring mark information about, on the basis of the acquired mark information by the acquisition process, executes a correction process for correcting the formation position of the image on the sheet.

  The present invention includes various aspects such as an image forming apparatus, an image forming position correction method for a sheet, a computer program for realizing the functions of these methods or apparatuses, and a non-volatile recording medium on which the computer program is recorded. Can be realized.

  According to the invention disclosed in this specification, the image formation position on the sheet can be corrected by at least one of a configuration different from the conventional configuration and a configuration obtained by improving the conventional configuration.

1 is a schematic diagram of an internal configuration of a multifunction peripheral according to an embodiment. Block diagram showing the electrical configuration of the MFP Flow chart showing control processing The figure which illustrates the pattern for main scanning of yellow, and the pattern for subscanning Diagram showing the relationship between the number of marks and the correction value The figure which illustrates the pattern for main scanning, and the pattern for subscanning

  A multifunction device 1 according to an embodiment will be described with reference to FIGS. In the following description, it is assumed that the depth direction in the drawing is the main scanning direction X, and the horizontal direction in the drawing is the sub-scanning direction Y.

  The multifunction machine 1 includes a printing unit 2 and a scanner unit 3 and can execute a copy function, an image reading function, and the like. The multifunction device 1 is an example of an image forming apparatus.

  The printing unit 2 has a direct transfer tandem configuration that can form a color image using, for example, four colors (black, yellow, magenta, and cyan). In the following description, when distinguishing each component or term of the multifunction device 1 for each color, K (black), Y (yellow), M (magenta), meaning each color at the end of the code of the component, etc. C (cyan) shall be attached. In FIG. 1, reference numerals are appropriately omitted for the same components between the respective colors.

  The printing unit 2 includes a tray 21, a sheet conveying belt 22, an image forming unit 23, a discharge tray 24, and the like. The tray 21 is provided at the bottom of the multifunction machine 1 and stores a printing sheet W. The sheets W stored in the tray 21 are taken out one by one by the pickup roller 25 and conveyed to the registration rollers 26 and 26. The conveyed sheet W is fed onto the belt 22 at a predetermined timing while the posture is adjusted by the registration rollers 26 and 26.

  The image forming unit 23 includes four process units 27 </ b> K to 27 </ b> C corresponding to each color and a fixing device 28. Each process unit 27 forms an image of the color toner contained therein on the sheet W conveyed by the belt 22. The sheet W on which the image is formed is heat-fixed by the fixing device 28 and discharged onto the discharge tray 24.

  The scanner unit 3 is provided above the discharge tray 24 and includes a document table 31 and a document cover 32. The document table 31 is provided with a reading device 33 that can move in the horizontal direction. The reading device 33 is an example of an acquisition unit and a reading unit. The document cover 32 is supported on the document table 31 so as to be openable and closable, and includes a document tray 34, an automatic document feeder (hereinafter referred to as “ADF”) 35, and a document sensor 36.

  The ADF 35 is an example of a transport unit, and is rotationally driven by a stepping motor 40A and a motor driver 40B described later. Specifically, when a clock signal is input from a CPU 41 (to be described later), the motor driver 40B rotates the stepping motor 40A by one step (predetermined angle) for each pulse of the clock signal. G is conveyed by a distance corresponding to one step.

  The scanner unit 3 can execute “original placement scan (hereinafter referred to as“ FB scan ”)” and “original feed scan (hereinafter referred to as“ ADF scan ”) as a method of scanning an image on the original G. It is. In the case of the FB scan, the operator places the document G on the document table 31, closes the document cover 32, and instructs the execution of the scan function. Then, the reading device 33 reads the original image of the original G while moving, generates the read data, and transmits it to the CPU 41 (see FIG. 2) built in the printing unit 2.

  In the case of ADF scanning, the operator sets the document G on the document tray 34 and instructs execution of the scan function. Then, the original G is conveyed page by page by the ADF 35 into the reading area of the reading device 33, and then discharged to the original discharge tray 37. The reading device 33 reads a document image from the document G being conveyed, generates read data, and transmits the read data to the CPU 41. The document sensor 36 outputs a detection signal corresponding to the presence or absence of the document G on the document tray 34.

  2, the multifunction device 1 includes a central processing unit (hereinafter referred to as CPU) 41, a ROM 42, a RAM 43, and a nonvolatile memory in addition to the image forming unit 23, the reading device 33, the ADF 35, the document sensor 36, and the motor driver 40B. 44, an application specific integrated circuit (ASIC) 45, a display unit 46, an operation unit 47, and a communication unit 48.

  Various programs are stored in the ROM 42, and the various programs include, for example, a program for executing a control process described later and a program for controlling the operation of each unit of the multifunction machine 1. . The RAM 43 is used as a work area when the CPU 41 executes various programs and as a temporary storage area for data. The non-volatile memory 44 may be any rewritable memory such as NAVRAM, flash memory, HDD, EPPROM.

  The CPU 41 is an example of a control unit, and is connected to the ROM 42, the RAM 43, and the like, and controls each unit of the multifunction device 1 according to a program read from the ROM 42. The ASIC 45 is a hardware circuit dedicated to image processing. The display unit 46 includes a liquid crystal display, a lamp, and the like, and can display various setting screens and operation states of the apparatus.

  The operation unit 47 is an example of an acquisition unit, has a plurality of buttons, and can accept various input instructions by an operator. The communication unit 48 is an example of an acquisition unit, and is an interface for communicating with an external device such as the image reading device 50 by a wireless communication method or a wired communication method. The multi-function device 1 can accept a reading instruction based on an operator's input operation through the operation unit 47, or can accept a reading instruction transmitted from an external device through the communication unit 48.

  With reference to FIG. 3, the control content which CPU41 performs is demonstrated. When the power of the multifunction device 1 is turned on, the CPU 41 repeatedly executes the control process shown in FIG. 3 periodically, for example. This control process is a process in which the CPU 41 determines the position at which each process unit 27 forms an image on the sheet W, in other words, the formation timing. Hereinafter, the control process will be described mainly using the yellow process unit 27Y as an example.

  First, the CPU 41 determines whether or not an execution condition for position determination is satisfied (S1). The execution conditions include, for example, that the operation unit 47 has received an input operation of a position determination execution instruction, and that the communication unit 48 has received a position determination execution instruction from an external device. Is performed, for example, during the manufacturing stage or maintenance of the multifunction machine 1.

  When the CPU 41 determines that the position determination execution condition is not satisfied (S1: NO), the CPU 41 stands by and determines that the position determination execution condition is satisfied (S1: YES). The operation of conveying the sheet W accommodated in is started (S2). The process of S2 is an example of a conveyance process and a conveyance process.

  Next, the CPU 41 determines the image density when the process unit 27 using the toner with relatively low visibility forms the patterns P1 and P2 described below than the process unit 27 using the toner with high visibility. The image density condition is changed so as to increase (S3). Specifically, the CPU 41 makes the developing bias value in the yellow process unit 27Y larger than that in the black process unit 27K. Accordingly, in the reading process described later, the marks M1Y and M2Y of the yellow patterns P1Y and P2Y can be accurately read. The CPU 41 may also increase the developing bias value in the magenta and cyan process units 27M and 27C.

  After changing the image density condition, the CPU 41 causes the image forming unit 23 to form the main scanning pattern P1 and the sub-scanning pattern P2 for each color in the process in which the sheet W is conveyed by the belt 22 (S4). . The process of S4 is an example of a pattern forming process and a pattern forming process. The main scanning pattern P1 is a pattern for determining the formation position in the main scanning direction X of each color image on the sheet W, and the sub scanning pattern P2 is the formation in the sub scanning direction Y of each color image on the sheet W. It is a pattern for determining a position.

  FIG. 4 illustrates a yellow main scanning pattern P1Y and a sub-scanning pattern P2Y. In the figure, it is assumed that the lower side in the drawing is the downstream side in the transport direction. The main scanning pattern P1Y is formed at one of the four sides of the sheet W substantially along the sub-scanning direction Y, and at a position straddling the left side in FIG. The main scanning pattern P1Y has a shape in which a plurality of marks M1Y are arranged at intervals in the sub-scanning direction Y, and the plurality of marks M1Y has a bar shape along the main scanning direction X, and is on the sheet W side. The position of the right edge in FIG. 4 is different in the main scanning direction X in FIG.

  Since each mark M1Y has a bar shape, the visibility of the number of marks M1Y on the sheet W on which the pattern P1Y is formed can be improved as compared with, for example, each mark M1Y having a dot shape. . Further, the mark M1Y has a longer length in the main scanning direction X as the mark M1Y closer to the side where the end on the sheet W side faces the side over which the main scanning pattern P1Y extends, in FIG. As a result, the amount of toner used for forming the mark M1Y can be saved while improving the visibility as compared with the case where all the marks M1Y have the same length in the main scanning direction X.

  Further, a plurality of main scanning patterns P1Y are formed on the same side. In FIG. 4, the main scanning pattern P1Y is formed on the leading end side and the trailing end side of the sheet W in the sub-scanning direction Y, respectively. Thereby, it is possible to acquire the inclination angle of the sheet W with respect to the transport direction from the difference in the number of marks M1Y on the sheet W of both patterns P1Y.

  As can be seen from the figure, when the relative position in the main scanning direction X between the sheet W and the image forming position of the process unit 27Y changes, the mark M1Y formed on the sheet W is accordingly changed. The number changes. Specifically, when the image formation position on the sheet W is shifted to the right side in FIG. 4, the number of marks M1Y on the sheet W is increased by that amount, and conversely, the image formation position on the sheet W is on the left side. The number of marks M1Y on the sheet W decreases accordingly. Therefore, the shift in the main scanning direction of the process unit 27Y with respect to the sheet W can be grasped from the number of marks M1Y on the sheet W.

  The sub-scanning pattern P <b> 2 </ b> Y is formed at one of the four sides of the sheet W along the main scanning direction X, the position across the upper side in the figure. Further, the sub-scanning pattern P2Y has a shape in which a plurality of marks M2Y are arranged at intervals in the main scanning direction X, and the plurality of marks M2Y has a bar shape along the sub-scanning direction Y, and is on the sheet W side. The position of the lower end of FIG. 4 is different from that of FIG.

  Since each mark M2Y has a bar shape, the visibility of the number of marks M2Y on the sheet W on which the pattern P2 is formed can be improved as compared with, for example, each mark M2Y having a dot shape. . Further, the mark M2Y has a longer length in the sub-scanning direction Y as the mark M2Y whose end on the sheet W side faces the side over which the sub-scanning pattern P2Y is straddled, in FIG. Thereby, compared to the case where all the marks M2Y have the same length in the sub-scanning direction Y, the amount of toner used for forming the mark M2Y can be saved while improving the visibility.

  Further, a plurality of sub-scanning patterns P2Y are formed for the same side. In FIG. 4, sub-scanning patterns P2Y are formed on the right end side and the left end side of the sheet W in the main scanning direction X, respectively. Thereby, it is possible to acquire the inclination angle of the sheet W with respect to the transport direction from the difference in the number of marks M2Y on the sheet W of both patterns P2Y.

  As can be seen from the figure, when the relative position in the sub-scanning direction Y between the sheet W and the image forming position of the process unit 27Y changes, the mark M2Y formed on the sheet W is accordingly changed. The number changes. Specifically, when the image formation position on the sheet W is shifted to the lower side in FIG. 4, the number of marks M2Y on the sheet W is increased by that amount, and conversely, the image formation position on the sheet W is increased. When shifted upward, the number of marks M2Y on the sheet W decreases accordingly. Therefore, the shift in the sub-scanning direction Y with respect to the sheet W of the process unit 27Y can be grasped from the number of marks M2Y on the sheet W.

  After forming the patterns P1 and P2, the CPU 41 causes the motor driver 40B to discharge the sheet W on which the patterns P1 and P2 are formed to the discharge tray 24, and then stops the conveying operation (S5). Next, the CPU 41 determines whether or not the document G is set on the document tray 34 based on the detection signal from the document sensor 36 (S6), and determines that the document G is not set (S6: NO) Wait.

  On the other hand, when the sheet P formed with the patterns P1 and P2 and discharged to the discharge tray 24 is set on the document tray 24, the CPU 41 determines that the document G is set (S6: YES), and accordingly. Then, the operation of conveying the sheet W is started by the ADF 35 (S7), and the operation of reading the image on the sheet W is executed by the reading device 33 (S8). The process of S7 is an example of a transport process, the process of S8 is an example of an acquisition process, an acquisition process, a reading process, and a reading process, and the read data output by the reading device 33 is an example of mark information.

  Here, with respect to the marks M1Y of the main scanning pattern P1Y, the interval D1 in the sub-scanning direction Y is equal to or greater than the unit conveyance distance in which the ADF 35 conveys the sheet W within one reading line cycle of the reading device 33. Accordingly, it is possible to prevent the reading device 33 from reading out the mark M1Y on the sheet W compared to the configuration in which the interval between the marks M1Y is less than the unit transport distance.

  Further, the distance D2 in the sub-scanning direction Y between the marks M2Y on the sheet side of the mark M2Y of the sub-scanning pattern P2Y is equal to or greater than the unit transport distance. Accordingly, it is possible to suppress the reading device 33 from reading out the mark M2Y on the sheet W compared to the configuration in which the distance D2 between the sheet-side ends of each mark M2Y is less than the unit transport distance.

  The CPU 41 analyzes the read image based on the read data acquired from the reading device 33, and acquires the number of marks on the sheet W of each pattern P1, P2 (S9). In the example of FIG. 4, each of the patterns P1 and P2 has three marks. Next, the CPU 41 determines the inclination angle of the sheet W based on the number of marks (S10). Specifically, the CPU 41 determines whether or not the difference in the number of marks between the two main scanning patterns P1 is equal to or greater than a specified number. This is an example of determination processing. The specified number is a value corresponding to an angle at which the sheet W is inclined with respect to the conveyance direction such that the image cannot be read normally, for example, three.

  The CPU 41 determines correction values in the main scanning direction X and the sub-scanning direction Y in response to determining that the difference in the number of marks is less than the specified number (S10: NO). As shown in FIG. 5, the non-volatile memory 44 stores a table indicating the correspondence between the number of marks and the correction value in advance, and the CPU 41 performs correction based on the number of marks and the table acquired in S9. Determine the value.

  In the example of FIG. 4, if the number of marks M1Y of the main scanning pattern P1Y is 3, there is no deviation between the image forming position of the process unit 27Y and the normal position, and the correction value is zero. If the number of the marks M1Y is two, the image formation position of the process unit 27Y is shifted by 0.1 mm in one direction (left side of the drawing in the figure) from the normal position. Therefore, the correction value is −0.1 mm in order to shift in the reverse direction (right side of the sheet).

  The CPU 41 determines correction values for each color in the main scanning direction X and the sub-scanning direction Y, rewrites and updates the contents of the nonvolatile memory 44 with the latest correction values (S11), and ends the control process. The control process is started again after a predetermined time. The process of S11 is an example of a correction process and a correction process. That is, the CPU 41 executes the correction process on the condition that the inclination angle of the sheet W with respect to the transport direction is within a specified range.

  On the other hand, when the CPU 41 determines that the difference in the number of marks is equal to or greater than the specified number (S10: YES), the CPU 41 executes error processing (S12) and returns to S1. In this error processing, since the sheet W is greatly inclined, it is impossible to form a pattern or to read the mark normally, and a message indicating that it is necessary to start again from the beginning is displayed on the display unit 46, or via the communication unit 48. Notify external devices. The process of S12 is an example of a notification process. Accordingly, it is possible to notify the outside that an abnormality such as the sheet W being greatly inclined is generated in the pattern formation process or the reading process.

  According to the present embodiment, when the image formation position on the sheet W is shifted, the numbers of the marks M1 and M2 on the sheet W on which the patterns P1 and P2 are formed are different. Then, the image formation position on the sheet W is corrected based on the mark information regarding the number of the marks M1 and M2. Accordingly, the image formation position on the sheet W can be corrected by at least one of a configuration different from the conventional configuration and a configuration obtained by improving the conventional configuration.

  Here, in the conventional configuration, since it is essential to calculate the size of each mark on the sheet and the distance between the marks, for example, the mark due to the difference between the printing magnification of the printing unit 2 and the reading magnification of the scanner unit 3 As a result, the image forming position on the sheet may not be accurately corrected. On the other hand, in the present embodiment, since the number of marks M1 and M2 is used, the image forming position on the sheet is hardly affected by the difference between the printing magnification of the printing unit 2 and the reading magnification of the scanner unit 3. Can be accurately corrected

  The processes from S4 to S8 to S11 are individually executed for each of the process units 27K to 27C. For this reason, the image forming position on the sheet W can be corrected for each process unit 27.

  The technology disclosed in the present specification is not limited to the embodiments described with reference to the above description and drawings, and includes, for example, the following various aspects.

  The “image forming apparatus” is not limited to a multifunction machine, and may be a copier, a facsimile machine, or a single printer. The image forming apparatus may be a monochrome-only apparatus or an apparatus that does not have a sheet conveying belt.

  In FIG. 2, the multifunction peripheral 1 and the image reading device 50 may constitute an image forming system. In this case, the image reading device 50 may read the image of the sheet W on which the patterns P <b> 1 and P <b> 2 are formed by the multifunction device 1, and give the read data to the CPU 41 of the multifunction device 1. In this system, the multifunction device 1 may be configured without the scanner unit 3. Further, the image reading device 50 acquires the number of marks based on the read data, gives information related to the number of marks to the CPU 41 of the multi function device 1, calculates a correction value based on the number of marks, and the correction value. May be provided to the CPU 41 of the multifunction device 1.

  Further, the operator views the sheet W on which the patterns P1 and P2 are formed by the multifunction machine 1 with his own eyes, counts the number of marks of each pattern P1 and P2, and determines the number of the marks. The configuration may be such that input is performed via one operation unit 47. In this case, it is not necessary to use the scanner unit 3 or the image reading apparatus.

  The “image forming unit” is not limited to the tandem method, and may be an intermediate transfer method, a 4-cycle method, or the like. The “image forming unit” may be an electrophotographic system or an inkjet system.

  The “reading unit” may be built in the printer body. For example, the printing unit 2 in FIG. 1 may include a reading device that reads an image of the sheet W on which an image is formed on the downstream side of the process unit 27. The printing unit 2 may include a sensor that outputs a detection signal corresponding to the presence or absence of a mark on the sheet W on which the image is formed, on the downstream side of the process unit 27. In these configurations, the belt 22 is an example of a transport unit.

  The control unit is configured to execute each process of FIG. 3 by one CPU 41. However, the present invention is not limited to this, and the control unit is configured to execute each process of FIG. 3 by a plurality of CPUs, to execute each process of FIG. 3 only by a dedicated hardware circuit such as the ASIC 45, or by a CPU and hardware circuit. A configuration in which each process of FIG. 3 is executed may be employed.

  In S <b> 3, the CPU 41 may increase the developing bias value in the process unit 27, in other words, the image density, higher than that during the printing process on the sheet W based on the printing instruction. Further, the CPU 41 may proceed to S4 without performing the process of S3 after the process of S2.

  In S <b> 4, the CPU 41 may form only one of the main scanning pattern P <b> 1 and the sub-scanning pattern P <b> 2 in the image forming unit 23.

  The “mark” is not limited to a rod shape, and may be a square shape or a round shape, for example. The marks may all be the same length.

  The CPU 41 executes the ADF scan in S7 and S8, but is not limited thereto, and the image on the sheet W may be read by the FB scan.

  In S10, the CPU 41 may determine whether or not the difference in the number of marks between the two sub-scanning patterns P2 is equal to or greater than a specified number.

  For example, the CPU 41 executes the processes from S4, S8 to S11 to one process unit 27, and uses the correction value for correcting the image forming position of the other process unit 27. Good.

  FIG. 6 shows a modification of the main scanning pattern P1 and the sub-scanning pattern P2. In the figure, it is assumed that the lower side in the drawing is the downstream side in the transport direction. The main scanning pattern P3 is formed at one of the four sides of the sheet W substantially along the sub-scanning direction Y, and at a position straddling the left side in FIG. The main scanning pattern P3 has a shape in which a plurality of marks M3 are arranged at intervals in the main scanning direction X, and the plurality of marks M3 has a bar shape along the sub-scanning direction Y, and is on the sheet W side. 6, the right end in FIG. 6, in other words, the position of the right side of the bar is different from each other in the main scanning direction X. The plurality of marks M3 may have the same length, or the number of marks M3 may be easily counted by changing the length for each predetermined number, such as every five or every ten.

  The main scanning pattern P4 is formed at a position straddling the left side in FIG. Further, the main scanning pattern P4 has a shape in which a plurality of marks M4 are arranged at intervals in the sub-scanning direction Y, and the plurality of marks M4 has a bar shape along the main scanning direction X and is on the sheet W side. And the right edge of the drawing are different from each other in the main scanning direction X. In FIG. 6, the plurality of marks M4 are longer on the downstream side in the transport direction, but may be shorter on the downstream side in the transport direction. The main scanning patterns P1, P3, and P4 may be formed so as to straddle the downstream side in the conveyance direction of the sheet W, that is, the lower side in FIG.

  The sub-scanning pattern P5 is formed at one of the four sides of the sheet W that extends along the main scanning direction X, that is, at the position across the upper side in the figure. Further, the sub-scanning pattern P5 has a shape in which a plurality of marks M5 are arranged at intervals in an oblique direction with respect to the transport direction, and the plurality of marks M5 are round and end on the sheet W side, FIG. Then, the position of the lower end of the page is different. The mark M5 may be square or rod-shaped.

  The sub-scanning pattern P6 is formed at a position straddling the upper side in the figure. Further, the sub-scanning pattern P6 has a shape in which a plurality of marks M6 are arranged at intervals in an oblique direction with respect to the transport direction, and the plurality of marks M5 have a bar shape along the oblique direction, and are on the sheet W side. The position of the lower end of FIG. The sub-scanning patterns P2, P5, and P6 may be formed so as to straddle the right side of the sheet W.

  1: MFP 23: Image forming unit 27: Process unit 33: Reading device 35: ADF 41: CPU P1, P2: Pattern M1, M2: Mark

Claims (13)

An image forming unit;
An acquisition unit;
A control unit,
The controller is
A pattern forming process in which the image forming unit forms a pattern having a plurality of marks at a position straddling a side of the sheet in at least one of a main scanning direction and a sub-scanning direction, wherein the plurality of marks are The pattern forming process in which the position of the end on the sheet side in the one direction is different from each other;
An acquisition process in which the acquisition unit acquires mark information corresponding to the number of marks on the sheet on which the pattern is formed;
An image forming apparatus that executes a correction process for correcting an image formation position on a sheet based on the mark information acquired in the acquisition process. The image forming apparatus according to claim 1,
Each of the marks is an image forming apparatus having a bar shape along the one direction. The image forming apparatus according to claim 1, wherein:
The image forming apparatus, wherein the plurality of marks have a longer length in the one direction as a mark whose end on the sheet side is closer to a side facing the side on which the pattern straddles. The image forming apparatus according to any one of claims 1 to 3,
With a transport section,
The acquisition unit is a reading unit,
The controller is
A conveying process for conveying the sheet on which the pattern is formed to the conveying unit;
A reading process for causing the reading unit to read a mark on a sheet conveyed by the conveyance unit, and
The pattern includes a plurality of marks straddling a side of the sheet in the main scanning direction, and the plurality of marks are arranged at intervals in the sub-scanning direction. An image forming apparatus that is equal to or longer than a sheet conveyance distance of the conveyance unit within a line cycle. The image forming apparatus according to any one of claims 1 to 3,
With a transport section,
The acquisition unit is a reading unit,
The controller is
A conveying process for conveying the sheet on which the pattern is formed to the conveying unit;
A reading process for causing the reading unit to read a mark on a sheet conveyed by the conveyance unit, and
The pattern spans the side of the sheet in the sub-scanning direction,
The plurality of marks are arranged at intervals in the main scanning direction, and the distance in the sub-scanning direction between the marks on the sheet side of each mark is the distance of the conveyance unit within the reading line period of the reading unit. An image forming apparatus having a sheet conveying distance or more. An image forming apparatus according to any one of claims 1 to 5,
The image forming unit includes a plurality of process units that form images with different colorants.
The control unit is an image forming apparatus that executes the pattern formation process, the acquisition process, and the correction process for each of the plurality of process units. The image forming apparatus according to claim 6,
The plurality of process units include two process units using colorants having different visibility from each other,
In the pattern forming process, the control unit uses the colorant having low visibility among the two process units to form the mark more than the process unit using a colorant having high visibility. An image forming apparatus that increases the image density at the time. The image forming apparatus according to claim 7,
The image forming apparatus, wherein the colorant having low visibility is yellow and the colorant having high visibility is black. The image forming apparatus according to any one of claims 1 to 8,
The controller is
In the pattern forming process, a plurality of the patterns are formed on the same side of the sheet,
Based on the mark information acquired in the acquisition process, a determination process for determining whether a difference in the number of marks between the patterns is a specified number or more;
An image forming apparatus that executes notification processing for notifying an error in response to determining that the difference in the number of marks between the patterns is equal to or greater than a specified number in the determination processing. The image forming apparatus according to any one of claims 1 to 8,
The controller is
In the pattern forming process, a plurality of the patterns are formed on the same side of the sheet,
Based on the mark information acquired in the acquisition process, a determination process is performed to determine whether a difference in the number of marks between the patterns is a specified number or more,
An image forming apparatus that executes the correction process on the condition that the difference in the number of marks between the patterns is determined to be less than a prescribed number in the determination process. An image forming system including an image forming apparatus and a reading device,
The image forming apparatus includes:
An image forming unit;
An image control unit,
The reader is
A reading unit;
A reading control unit,
The image control unit
A pattern forming process in which the image forming unit forms a pattern having a plurality of marks at a position straddling a side of the sheet in at least one of a main scanning direction and a sub-scanning direction, wherein the plurality of marks are , The pattern forming process is executed in which the positions of the end on the sheet side in the one direction are different from each other,
The reading control unit
Causing the reading unit to read a mark on the sheet after the pattern formation processing,
The image control unit
An acquisition process for acquiring mark information related to the number of marks on the sheet on which the pattern is formed, based on a reading result of the reading process in the reading device;
An image forming system that executes correction processing for correcting an image forming position on a sheet based on the mark information acquired in the acquisition processing. In an image forming apparatus including an image forming unit and an acquisition unit,
A pattern forming process in which the image forming unit forms a pattern having a plurality of marks at a position straddling a side of the sheet in at least one of a main scanning direction and a sub-scanning direction, wherein the plurality of marks are The pattern forming process in which the position of the end on the sheet side in the one direction is different from each other;
An acquisition process in which the acquisition unit acquires mark information regarding the number of marks on the sheet on which the pattern is formed;
A forming position correction program for executing a correction process for correcting an image forming position on a sheet based on the mark information acquired in the acquisition process. A method for correcting a forming position for a sheet of an image forming apparatus, comprising:
A pattern forming step of forming a pattern having a plurality of marks at a position straddling a side of a sheet in at least one of a main scanning direction and a sub-scanning direction using the image forming apparatus, The mark is a pattern forming step in which the position of the sheet side end in the one direction is different from each other, and
A reading step of reading a mark on the sheet after the pattern forming step using the reading device;
In the image forming apparatus, an acquisition step of acquiring mark information related to the number of marks on the sheet on which the pattern is formed based on a reading result of the reading step;
And a correction step of correcting the image formation position on the sheet based on the mark information acquired in the acquisition step.

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