Image forming control method and image forming apparatus

Abstract

The invention provides an image forming control method and an image forming apparatus. The purpose of the present invention is to accurately set the center position in the width direction of a region in which the edge of a sheet is detected, on the basis of a test image formed on the sheet, without the need to visually confirm the image. The processor causes the sheet conveying device to execute a process of conveying a target sheet in a state in which a specific surface on which a first test image including a plurality of black patch images arranged in a stepped manner is formed is a printing surface. The processor supplies data of a second test image including a plurality of line segment images corresponding to the plurality of black patch images to the image processing device as reference image data, and acquires information of a test interference position, which is a position at which a masking region corresponding to the plurality of black patch images interferes with the second test image. The processor sets a reference center position according to the test interference position.

Description

Technical Field

[0001] The present invention relates to an image forming control method and an image forming apparatus capable of adjusting the position of a print target image based on a detection result of the positions of both edge ends in the width direction of a conveyed sheet. Background Art

[0002] The image forming apparatus may include an edge detection unit capable of detecting the positions of both ends of a sheet being conveyed in the width direction. The edge detection unit is disposed upstream of the printing device in the sheet conveying direction.

[0003] It is known that the image forming apparatus determines the center position in the width direction of the sheet, i.e., the sheet center position, based on the detection result of the edge detection unit, and adjusts the position of the print target image in the width direction according to the sheet center position (for example, refer to Patent Document 1).

[0004] It is also known that the image forming device forms a test image including a plurality of scale images on both sides of a sheet in order to correct the deviation of the center position in the width direction of the edge detection area. In this case, the image forming device corrects the deviation of the center position of the edge detection area based on the overlapping state of the plurality of scale images on both sides of the sheet when the sheet is viewed through.

[0005] The overlapping state of the plurality of scale images on both surfaces of the sheet can be visually confirmed.

[0006] However, when the overlapping state of the plurality of scale images on both sides of the sheet is visually checked, errors in the visual check may adversely affect the correction of the deviation of the center position of the edge detection area. Summary of the invention

[0007] An object of the present invention is to provide an image formation control method and an image forming apparatus capable of accurately setting the center position in the width direction of a region where an edge of a sheet is detected based on a test image formed on the sheet without visually checking the image.

[0008] An image forming control method according to one aspect of the present invention is a method for controlling an image forming device. The image forming device includes a sheet conveying device, a printing device, a black reference component, an image sensor unit, and an image processing device. The sheet conveying device conveys a sheet along a conveying path. The printing device forms an image on the sheet conveyed along the conveying path. The black reference component has a black reference surface, and the reference surface is arranged along a width direction intersecting the sheet conveying direction in a state of facing a detection area in the conveying path located on the upstream side of the sheet conveying direction relative to the printing device. The image sensor unit is arranged along the width direction in a state of facing the reference surface with the detection area interposed therebetween, emits detection light toward the reference surface, detects the light amount of reflected light of the detection light, and outputs a plurality of line image data, each of the plurality of line image data including detection light amounts corresponding to a plurality of unit areas divided in the width direction in the detection area. The image processing device performs image processing based on the plurality of line image data. The image processing device is capable of executing an area detection process, the area detection process is a process of detecting a pair of lateral edge positions, a sheet area, and a shielding area, the pair of lateral edge positions being positions of both ends of the sheet in the width direction passing through the detection area, the sheet area being an area within the outline of a quadrilateral of the sheet, and the shielding area being a portion of the sheet area where the detected light quantity is lower than a reference light quantity. Furthermore, the image processing device is capable of executing an interference position determination process, the interference position determination process is a process of determining the position of an interference portion overlapping the shielding area in a reference image represented by the supplied reference image data. The image formation control method includes: when the operation mode is the first mode, the processor causes the sheet conveying device to execute a first conveying process, the first conveying process conveying the target sheet in a state where a blank specific surface of the target sheet becomes a printing surface. The image formation control method also includes: the processor obtaining information of a pair of lateral edge positions, i.e., a pair of first lateral edge positions, detected by the image processing device when executing the first conveying process. The image formation control method further includes: the processor causes the printing device to execute a process of forming a first test image including a plurality of black patch images on the specific surface when executing the first conveying process. The image formation control method further includes: the processor causes the sheet conveying device to execute a second conveying process, wherein the second conveying process is a process of conveying the target sheet in a state where the specific surface on which the first test image is formed becomes a printing surface. The image formation control method further includes: the processor obtains information on a pair of the lateral edge positions, i.e., a pair of second lateral edge positions, detected by the image processing device when executing the second conveying process.The image formation control method further includes: the processor supplies data of a second test image including a plurality of line segment images corresponding to the plurality of black patch images and respectively along the sheet conveying direction as the reference image data to the image processing device, and obtains information of a test interference position, wherein the test interference position is the position of the interference portion determined by the image processing device based on the shielding area corresponding to the second conveying process and the data of the second test image. The image formation control method further includes: the processor sets the center position of the image sensor unit in the width direction, i.e., the reference center position, according to the test interference position. The image formation control method further includes: the processor performs a width position correction process when the action mode is the second mode, wherein the width position correction process is a process of correcting the position of the print target image in the width direction each time the sheet is conveyed based on the difference between the center position of a pair of the lateral edge positions detected by the image processing device each time the sheet is conveyed and the reference center position. The image formation control method further includes: the processor executing a masking process, wherein the masking process is a process of supplying the data of the print target image subjected to the width position correction process to the image processing device as the reference image data, and replacing the pixels corresponding to the position of the interference portion determined by the image processing device in the print target image with non-printing pixels. The image formation control method further includes: the processor causing the printing device to execute a process of forming the print target image subjected to the width position correction process and the masking process on the sheet. The plurality of black patch images in the first test image are square black-painted images arranged in a step-like manner at intervals of a reference length in the width direction with reference to the center position of a pair of the first lateral edge positions in a state where the positions in the sheet conveying direction are sequentially shifted, and each of which has a width of the reference length. The plurality of line segment images in the second test image are arranged at equal intervals less than the reference length in the width direction with reference to the center position of the pair of the second lateral edge positions, and each end of the plurality of line segment images is formed at a position overlapping with a corresponding one of the plurality of black patch images in the sheet conveying direction.

[0009] An image forming apparatus according to another aspect of the present invention includes the sheet conveying apparatus, the printing apparatus, the black reference member, the image sensor unit, the image processing apparatus, and the processor.

[0010] According to the present invention, an image forming control method and an image forming apparatus can be provided that can accurately set the center position in the width direction of a region where an edge of a sheet is detected based on a test image formed on the sheet without visually checking the image.

[0011] This specification is presented in a simplified form, with appropriate reference to the accompanying drawings, to summarize the concepts described in the following detailed description. This specification is not intended to limit the important features and essential features of the subject matter described in the claims, nor is it intended to limit the scope of the subject matter described in the claims. In addition, the subject matter described in the claims is not limited to implementations that solve some or all of the disadvantages described in any part of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a block diagram of an image forming apparatus according to an embodiment.

[0013] Figure 2 This is a block diagram showing the configuration of a control device of the image forming apparatus according to the embodiment.

[0014] Figure 3 It is a configuration diagram of a sheet measuring device of an image forming apparatus according to an embodiment.

[0015] Figure 4 It is a plan view of an image sensor unit and a black reference member included in the sheet measuring device of the image forming apparatus according to the embodiment.

[0016] Figure 5 This is a diagram showing an example of a first test image formed on a target sheet in the image forming apparatus according to the embodiment.

[0017] Figure 6 This is a diagram showing an example of a second test image represented by reference image data supplied to a sheet measuring device in the image forming apparatus according to the embodiment.

[0018] Figure 7 is an enlarged view of a portion of the first test image and the second test image.

[0019] Figure 8 This is a flowchart showing an example of a procedure of a center position correction process of the image forming apparatus according to the embodiment.

[0020] Fig. 9 This is a flowchart showing an example of the procedure of the second test image data supply process of the image forming apparatus of the application example. DETAILED DESCRIPTION

[0021] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the following embodiment is an example of embodying the present invention and does not limit the technical scope of the present invention.

[0022] [Structure of Image Forming Apparatus 10] The image forming apparatus 10 of the present embodiment includes a sheet storage unit 1 , a sheet conveying device 3 , and a printing device 4 .

[0023] The sheet conveying device 3 includes a sheet feeding mechanism 30 , a plurality of conveying roller pairs 31 , a first belt conveying device 32 , and a second belt conveying device 33 . The sheet feeding mechanism 30 feeds the sheets 9 in the sheet storage unit 1 to the main conveying path 301 .

[0024] Some of the plurality of conveying roller pairs 31 convey the sheet 9 along the main conveying path 301 , and further send the sheet 9 to the first belt conveyor device 32 .

[0025] The first belt conveyor 32 conveys the sheet 9 from the plurality of conveyor roller pairs 31 and sends the sheet 9 to the second belt conveyor 33. The second belt conveyor 33 conveys the sheet 9 from the first belt conveyor 32 and sends the sheet 9 to the rear conveying path 302.

[0026] Some of the plurality of conveying roller pairs 31 convey the sheet 9 along the rear conveying path 302 and deliver the sheet 9 to a rear portion such as a discharge tray or a post-processing device.

[0027] In addition, some of the plurality of conveying roller pairs 31 may convey the sheet 9 from the rear conveying path 302 to the reverse conveying path 303. The sheet conveying device 3 further includes a reverse mechanism 34 that reverses the sheet 9 in the reverse conveying path 303 and returns it to the main conveying path 301.

[0028] The main conveying path 301, the rear conveying path 302, and the reverse conveying path 303 are each a part of the conveying path of the sheet 9. In addition, the belts of the first belt conveyor 32 and the second belt conveyor 33 are also a part of the conveying path of the sheet 9.

[0029] The printing device 4 executes a printing process on the sheet 9 conveyed by the first belt conveying device 32 . The printing process is a process of forming an image on the sheet 9 .

[0030] In the present embodiment, the printing device 4 executes the printing process by an inkjet method. That is, the printing device 4 forms an image on the sheet 9 by ejecting ink onto the sheet 9. The ink is an example of a developer.

[0031] The printing device 4 includes a plurality of inkjet heads 41 corresponding to inks of different colors and a plurality of ink supply units 42. Specifically, the printing device 4 includes four inkjet heads 41 and four ink supply units 42 corresponding to yellow, magenta, cyan, and black.

[0032] The plurality of inkjet heads 41 each have a plurality of nozzles for ejecting ink. The plurality of inkjet heads 41 are fixed at positions facing the conveyor belt of the first belt conveyor 32. The plurality of ink supply units 42 each contain ink of a different color and supply ink to the plurality of inkjet heads 41.

[0033] In addition, a device that executes the above-mentioned printing process by other methods such as electrophotography can also be used as the printing device 4.

[0034] The first belt conveyor device 32 conveys the sheet 9 on which the image is formed to the second belt conveyor device 33 .

[0035] When the sheet 9 is first conveyed by the first belt conveyor 32 , the printer 4 forms an image on the first surface of the sheet 9 . When the sheet 9 having passed through the reverse conveying path 303 is secondarily conveyed by the first belt conveyor 32 , the printer 4 forms an image on the second surface of the sheet 9 .

[0036] exist Figure 1 , Figures 3 to 5 In the embodiment, the conveying direction D1 is the sheet conveying direction. The sheet conveying direction is the direction in which the sheet 9 is conveyed by the sheet conveying device 3. The width direction D2 is a direction intersecting the conveying direction D1. The width direction D2 is the main scanning direction of the printing process, and the conveying direction D1 is the sub-scanning direction of the printing process.

[0037] The printing device 4 further includes a drying device 43 having a heater 431 for heating the sheet 9. The drying device 43 is disposed on the downstream side of the printing device 4 in the conveying direction D1.

[0038] The drying device 43 includes a heater 431 for heating the sheet 9. The drying device 43 dries the ink on the sheet 9 conveyed by the second belt conveyor 33.

[0039] The drying device 43 further includes a fan 432. The fan 432 conveys the air heated by the heater 431 to the sheet 9 on the second belt conveyor 33. The drying device 43 further includes a temperature sensor 430 for detecting the temperature inside the drying device 43.

[0040] The image forming apparatus 10 further includes an operating device 801, a display device 802, and a control device 8 (see Figure 1 ).

[0041] The operation device 801 detects human operation. For example, the operation device 801 includes a plurality of operation buttons and a touch panel. The display device 802 can display various information. For example, the display device 802 is a panel display device such as a liquid crystal display panel.

[0042] like Figure 2As shown, the control device 8 includes a CPU (Central Processing Unit) 80, a RAM (Random Access Memory) 81, an auxiliary storage device 82, a communication device 83, and the like.

[0043] The CPU 80 performs various control and data processing by executing computer programs. The RAM 81 temporarily stores the computer programs executed by the CPU 80 and various data.

[0044] The auxiliary storage device 82 is a nonvolatile storage device that can be read by a computer. The auxiliary storage device 82 stores the computer program executed by the CPU 80 and various data. For example, one or both of a flash memory and a hard disk drive are used as the auxiliary storage device 82.

[0045] The communication device 83 communicates with other devices such as the host device 7 via the network 70. The CPU 80 communicates with other devices via the communication device 83. The host device 7 is an information processing device that requests the image forming device 10 to execute the above-mentioned printing process.

[0046] The CPU 80 includes a plurality of processing modules implemented by executing the computer program. The plurality of processing modules include a main control unit 8a and a print control unit 8b (see Figure 2 ).

[0047] The main control unit 8 a performs start control for starting various processes in response to an operation on the operating device 801 or a process request received via the communication device 83 .

[0048] The print control unit 8 b controls the sheet conveying device 3 and the printing device 4 . The print control unit 8 b controls conveyance of the sheet 9 by controlling the sheet conveying device 3 .

[0049] Furthermore, the print control unit 8b controls the printer 4 to execute the printing process in synchronization with the conveyance of the sheet 9. Furthermore, the print control unit 8b controls supplying power to the heater 431 of the drying device 43 and operating the fan 432 when executing the printing process on the print target image.

[0050] The image forming apparatus 10 further includes a sheet measuring device 5 (see Figure 1 , Figure 3 , Figure 4 The sheet measuring device 5 is arranged on the upstream side of the printing device 4 in the conveying direction D1.

[0051] In the following description, the area in the main conveying path 301 corresponding to the sheet measuring device 5 is referred to as a detection area A1 (see Figure 1, Figure 3 , Figure 4 The detection area A1 is an area located upstream of the printing device 4 in the conveying direction D1 (see Figure 1 ).

[0052] [Structure of Sheet Measuring Device 5] The sheet measuring device 5 includes a black reference member 51, an image sensor unit 52, and an image processing circuit 53 (see Figure 1 , Figure 3 ).

[0053] The black reference member 51 and the image sensor unit 52 are arranged along the width direction D2 (see Figure 4 The black reference member 51 and the image sensor unit 52 are arranged to face each other with the detection area A1 interposed therebetween (see Figure 1 , Figure 3 ).

[0054] The black reference member 51 has a black reference surface 51a (see Figure 3 The reference surface 51a is arranged along the width direction D2 in a state facing the detection area A1.

[0055] The image sensor unit 52 is arranged along the width direction D2 in a state of facing the reference surface 51a across the detection area A1 (see Figure 3 , Figure 4 The image sensor unit 52 includes a light emitting unit 5a, a lens 5b, and an image sensor 5c (see Figure 3 ).

[0056] The light emitting unit 5a emits detection light toward the reference surface 51a, and the lens 5b focuses reflected light of the detection light on the light receiving unit of the image sensor 5c.

[0057] The image sensor 5c is a line sensor having a plurality of photoelectric conversion elements arranged along the width direction D2. The image sensor 5c detects the light amount of the reflected light and sequentially outputs a plurality of line image data each including a plurality of pixel data.

[0058] The plurality of pixel data represent the detected light amounts corresponding to the plurality of unit areas divided in the width direction D2 in the detection area A1. The plurality of image data represent the light received by the plurality of photoelectric conversion elements, respectively.

[0059] The plurality of unit areas are areas obtained by dividing the detection area A1 having the width direction D2 as the longitudinal direction at a predetermined resolution. The reference center position SC1 is a position corresponding to a specific one of the plurality of pixel data of each line data.

[0060] All of the plurality of pixel data of each of the line image data obtained when the sheet 9 is not present in the detection area A1 represent the light amount of the reflected light reflected by the reference surface 51 a and are data lower than a preset reference light amount.

[0061] On the other hand, in each of the line image data obtained when the sheet 9 passes through the detection area A1 , data corresponding to the area of ​​the width of the sheet 9 among the plurality of pixel data is data of brightness corresponding to the state of the surface of the sheet 9 .

[0062] The image processing circuit 53 is a device that realizes image processing based on the plurality of line data by hardware. For example, the image processing circuit 53 is composed of an ASIC (Application Specific Integrated Circuit) or a DSP (Digital Signal Processor). The image processing circuit 53 is an example of an image processing device.

[0063] The image processing circuit 53 can perform area detection processing and interference position determination processing based on the plurality of line image data sequentially output from the image sensor unit 52 .

[0064] The area detection process is a process for detecting a pair of lateral edge positions E1, a sheet area, and a shielding area. The pair of lateral edge positions E1 are positions of both ends of the sheet 9 in the width direction D2 passing through the detection area A1 (see Figure 4 ). The thin-sheet body area is the area within the quadrilateral outline of the thin-sheet body 9.

[0065] The image processing circuit 53 detects a pair of lateral edge positions E1 by performing edge detection processing in the width direction D2 on each of the line data.

[0066] The image processing circuit 53 detects the leading and trailing ends of the sheet 9 by performing edge detection processing in the conveying direction D1 on the line data. The image processing circuit 53 determines the sheet area based on the detection results of the pair of lateral edge positions E1, the leading and trailing ends of the sheet 9.

[0067] Furthermore, the image processing circuit 53 specifies a portion of the sheet area where the detected light amount is lower than the reference light amount as the shielding area.

[0068] When the sheet 9 is formed with an opening 90 such as a punch hole, a portion of the reference surface 51a is exposed to the image sensor unit 52 through the opening 90 (see Figure 4 ). Therefore, the area of ​​the opening 90 of the sheet body 9 is detected as the shielding area.

[0069] When the reference image data is supplied to the image processing circuit 53, the image processing circuit 53 performs the interference position determination process. The interference position determination process is a process for determining the position of the interference portion overlapping the shielding area in the reference image represented by the supplied reference image data. In the following description, the position of the interference portion determined by the image processing circuit 53 is referred to as the interference position.

[0070] In the image forming apparatus 10, a reference center position SC1 (see Figure 4 ).

[0071] The reference center position SC1 is associated with a center position in the width direction D2 of a print width area, that is, a print center position. The print width area is an area in the width direction D2 where the printing device 4 can form an image.

[0072] In the following description, the center position of the pair of lateral edge positions E1 is referred to as a sheet center position PC1 (see Figure 4 The sheet center position PC1 is the center position in the width direction D2 of the sheet 9 passing through the detection area A1.

[0073] The state in which the sheet center position PC1 coincides with the reference center position SC1 is a state in which the sheet 9 is conveyed at a pre-assumed position in the width direction D2 .

[0074] The print control unit 8 b executes the width position correction process and the masking process every time a sheet 9 is conveyed.

[0075] The width position correction process is a process for correcting the position of the print target image in the width direction D2 based on the position difference DX1 between the sheet center position PC1 and the reference center position SC1 (see Figure 4 ).

[0076] The masking process is a process of providing the data of the print target image subjected to the width position correction process as the reference image data to the image processing circuit 53, and replacing the pixels corresponding to the interference position in the print target image with non-print pixels that are not drawn with ink.

[0077] The area detection process, the interference position determination process, the width position correction process, and the masking process need to be completed while the sheet 9 is being conveyed from the detection area A1 to the position of the printing device 4. The area detection process and the interference position determination process are realized at high speed by being implemented in hardware.

[0078] The print control unit 8b causes the printing device 4 to execute the print process on the print target image that has been subjected to the width position correction process and the masking process for each sheet 9. As a result, the print target image is formed at an appropriate position in the width direction D2 of the sheet 9. Furthermore, ink is prevented from being ejected into the area of ​​the opening 90 of the sheet 9.

[0079] However, when the reference center position SC1 is offset from the printing center position of the printing device 4 , the print target image is formed at a position offset to one side in the width direction D2 of the sheet 9 .

[0080] The plurality of processing modules of the CPU 80 further include a correction unit 8c. The print control unit 8b and the correction unit 8c perform the center position correction process described later (see Figure 8 The center position correction process is a process of correcting a deviation of the reference center position SC1 relative to the printing center position.

[0081] In the conventional apparatus, in order to correct the deviation of the reference center position SC1, a test image including a plurality of scale images is sometimes formed on both sides of the sheet 9. In this case, the conventional apparatus corrects the deviation of the reference center position SC1 based on the overlapping state of the plurality of scale images on both sides of the sheet 9 when the sheet 9 is viewed through.

[0082] The overlapping state of the plurality of scale images on both surfaces of the sheet 9 is visually checked.

[0083] However, when the overlapping state of the plurality of scale images on both surfaces of the sheet 9 is visually checked, errors in the visual check may adversely affect the correction of the deviation of the reference center position SC1 .

[0084] The image forming apparatus 10 has a configuration for accurately setting the center position of the detection area A1 in the width direction D2 based on the test image formed on the sheet 9 without visually checking the image. This configuration will be described below.

[0085] In the following description, the sheet 9 used for the center position correction process is referred to as a target sheet 9x (see Figure 5 to Figure 7 ).

[0086] In the present embodiment, when a correction start operation is detected by the operating device 801, the main control unit 8a switches the operation mode of the image forming apparatus 10 from the normal mode to the correction mode. The initial state of the operation mode is the normal mode.

[0087] When the operation mode is the calibration mode, the center position calibration process is executed. When the center calibration process is completed, the main control unit 8a returns the operation mode from the calibration mode to the normal mode.

[0088] When the operation mode is the normal mode, the print control unit 8 b causes the printing device 4 to execute both the width position correction process and the masking process on the print target image for each sheet 9 , and executes the printing process on the print target image on which the two processes have been executed.

[0089] The mask processing on the printing target image is the mask processing based on the interference position obtained by the interference position specifying processing using the data of the printing target image as the reference image data.

[0090] As described above, the position of the image to be printed in the width direction D2 is corrected by the width position correction process. Furthermore, the masking process prevents ink from being ejected onto the reference surface 51 a of the black reference member 51 .

[0091] The calibration mode is an example of the first mode, and the normal mode is an example of the second mode.

[0092] [Center position correction processing] Below, refer to Figure 7 The flowchart shown in the figure explains an example of the procedure of the center position correction processing.

[0093] The center position correction process is an example of a process for realizing an image formation control method for controlling the image forming apparatus 10. The CPU 80 is an example of a processor for realizing the image formation control method.

[0094] In the following description, S1, S2, ... denote identification codes of a plurality of steps of the center position correction process. In the center position correction process, the process of step S1 is first executed.

[0095] <Step S1> In step S1 , the print control unit 8 b executes control to stop supplying power to the heater 431 of the drying device 43 .

[0096] After executing the process of step S1, the print control unit 8b shifts the process to step S2. The processes after step S2 are executed in a state where the power supply to the heater 431 is stopped.

[0097] <Step S2> In step S2 , the calibration unit 8 c determines whether the temperature of the drying device 43 satisfies the temperature permission condition.

[0098] The temperature permission condition is a condition that the temperature detected by the temperature sensor 430 of the drying device 43 does not exceed a preset permission temperature. In step S2, the calibration unit 8c obtains the temperature detected by the temperature sensor 430 and determines whether the detected temperature satisfies the temperature permission condition.

[0099] The temperature permission condition is determined in order to prevent the target sheet 9x from shrinking when passing through the drying device 43.

[0100] If the temperature of the drying device 43 does not satisfy the temperature permission condition, the correction unit 8c shifts the process to step S3. On the other hand, if the temperature of the drying device 43 satisfies the temperature permission condition, the correction unit 8c shifts the process to step S4.

[0101] <Step S3> In step S3 , the correction unit 8 c executes error notification of pre-set error information via the display device 802 .

[0102] For example, the error information is information indicating a state in which the temperature of the drying device 43 does not satisfy the temperature permission condition and an operation that the user should perform in order to make the temperature of the drying device 43 satisfy the temperature permission condition.

[0103] After executing the process of step S3, the correction unit 8c ends the center position correction process. Alternatively, the correction unit 8c may repeatedly perform the processes of steps S2 and S3 until the temperature of the drying device 43 satisfies the temperature permission condition.

[0104] When the temperature of the drying device 43 does not satisfy the temperature permission condition, the print control unit 8 b may operate the fan 432 while stopping the power supply to the heater 431 of the drying device 43 . This promotes the cooling of the drying device 43 .

[0105] The processing after step S4 described below is performed on the condition that the temperature of the drying device 43 satisfies the temperature permission condition.

[0106] <Step S4> In step S4 , the print control unit 8 b causes the sheet conveying device 3 to execute a first conveying process for conveying the target sheet 9 x with the specific surface 9 a of the target sheet 9 x serving as a printing surface.

[0107] The specific surface 9a of the target sheet 9x to be subjected to the first conveying process is a blank surface on which no image is formed. When the first conveying process is executed, the processes of step S5 and step S6 are executed.

[0108] <Step S5> In step S5 , the correction unit 8 c acquires data of a pair of first lateral edge positions detected by the sheet measuring device 5 at the timing when the target sheet 9 x passes through the detection area A1 .

[0109] The pair of first lateral edge positions are a pair of lateral edge positions E1 obtained by the area detection process of the sheet measuring device 5 when the target sheet 9 x is conveyed by the first conveyance process.

[0110] After executing the process of step S5 , the correction unit 8 c shifts the process to step S6 .

[0111] <Step S6> In step S6, the print control unit 8b causes the printing device 4 to execute a process of forming a first test image G1 including a plurality of black patch images G11 on the specific surface 9a of the target sheet 9x (see Figure 5 , Figure 7 ).

[0112] The plurality of black patch images G11 in the first test image G1 are each a square black-painted image having a width of a first length L1 (see Figure 5 , Figure 7 ). The first length L1 is a preset reference length.

[0113] In this embodiment, data representing the first reference test image is pre-stored in the auxiliary storage device 82. The first reference test image includes a plurality of black patch images G11 arranged in a step-like manner at intervals of a first length L1 in the width direction D2 with reference to a reference center position SC1 while being sequentially shifted in the conveying direction D1.

[0114] The plurality of black patch images G11 are arranged in a step-like manner so as to be shifted from the first side to the second side in the width direction D2 toward the upstream side in the conveying direction D1 (see Figure 5 ).exist Figure 5 to Figure 7 In the example shown, the first side in the width direction D2 facing the paper is the right side, and the second side in the width direction D2 facing the paper is the left side.

[0115] In step S6 , the print control unit 8 b executes the width position correction process on the first reference test image.

[0116] That is, the print control unit 8 b corrects the position of the first test image G1 in the width direction D2 based on the reference center position SC1 based on the difference between the sheet center position PC1 at the center of the pair of first lateral edge positions obtained in step S5 and the reference center position SC1 .

[0117] The print control unit 8 b sets the image whose position in the width direction D2 is corrected by the width position correction process as the first test image G1 .

[0118] The plurality of black patch images G11 include a reference black patch image G110 (see Figure 5 , Figure 7 ). The reference black patch image G110 is one located at the center in the width direction D2 among the plurality of black patch images G11.

[0119] In the first reference test image, a specific side edge, which is one of the two side edges of the reference black patch image G110, is located at the reference center position SC1. Figure 5 , Figure 7 In the example shown, the specific side is the left side of the reference black patch image G110.

[0120] In the first test image G1 obtained by the width position correction process, the specific side edge of the reference black patch image G110 is located at the sheet center position PC1 (refer to Figure 5 ).

[0121] That is, in step S6, in the first test image G1 formed on the specific surface 9a of the target sheet 9x, the plurality of black patch images G11 are arranged in a step-like manner at intervals of the first length L1 in the width direction D2 with the sheet center position PC1 being the center of the pair of first lateral edge positions as a reference in a state where the positions are sequentially shifted in the conveying direction D1 (refer to FIG. Figure 5 ).

[0122] After executing the process of step S6 , the print control unit 8 b shifts the process to step S7 .

[0123] <Step S7> In step S7 , the print control unit 8 b causes the sheet conveying device 3 to execute a second conveying process of conveying the target sheet 9 x with the specific surface 9 a of the target sheet 9 x on which the first test image G1 is formed serving as the printing surface.

[0124] For example, in step S7, the main control unit 8a notifies the display device 802 of a target sheet setting message that urges the target sheet 9x to be set in the sheet storage unit 1 so that the specific surface 9a of the target sheet 9x on which the first test image G1 is formed becomes the printing surface.

[0125] When the operation device 801 detects the conveyance start operation corresponding to the target sheet setting message, the print control unit 8 b causes the sheet conveyance device 3 to execute the second conveyance process on the target sheet 9 x set in the sheet storage unit 1 .

[0126] When the second conveying process is executed, the plurality of black patch images G11 in the first test image G1 simulates the region of the opening 90 of the target sheet 9 x .

[0127] That is, the image processing circuit 53 executes the region detection process corresponding to the second conveyance process, and detects the region of the plurality of black patch images G11 as the mask region.

[0128] After executing the process of step S7, the print control unit 8b transfers the process to step S8. When executing the second transport process, the processes of step S8 and step S9 are executed.

[0129] <Step S8> In step S8 , the correction unit 8 c acquires data of a pair of second lateral edge positions from the sheet measuring device 5 at the timing when the target sheet 9 x passes through the detection area.

[0130] The pair of second lateral edge positions are a pair of lateral edge positions E1 obtained by the area detection process of the sheet measuring device 5 when the target sheet 9 x is conveyed by the second conveyance process.

[0131] After executing the process of step S8 , the correction unit 8 c shifts the process to step S9 .

[0132] <Step S9> In step S9, the print control unit 8b supplies the data of the second test image G2 including a plurality of line segment images G21 along the conveying direction D1 as the reference image data to the image processing circuit 53 (see Figure 6 ).

[0133] The plurality of line segment images G21 in the second test image G2 respectively correspond to the plurality of black patch images G11 in the first test image G1. Figure 6 In FIG. 1 , a plurality of black patch images G11 of the first test image G1 are indicated by dotted lines.

[0134] The plurality of line segment images G21 of the second test image G2 are arranged at equal intervals of the second length L2 in the width direction D2 with reference to the sheet center position PC1 that is the center of the pair of second lateral edge positions.

[0135] The second length L2 is shorter than the first length L1. Specifically, the second length L2 is shorter than the first length L1 by a length of one pixel.

[0136] Each end of the plurality of line segment images G21 is formed at a position overlapping with a corresponding one of the plurality of black patch images G11 in the conveyance direction D1 .

[0137] For example, the first end of each of the plurality of line segment images G21 is formed at a position on the downstream side of the transport direction D1 relative to all of the plurality of black patch images G11 (see Figure 6 ) The downstream side in the conveying direction D1 is the leading end side of the target sheet 9x to be conveyed.

[0138] On the other hand, the second end portion of each of the plurality of line segment images G21 is formed at a central position in the conveying direction D1 of a corresponding one of the plurality of black patch images G11 (see Figure 6 ).

[0139] In this embodiment, data representing the second reference test image is pre-stored in the auxiliary storage device 82. The second reference test image includes a plurality of line segment images G21 arranged at equal intervals of a second length L2 in the width direction D2 with reference to the reference center position SC1.

[0140] In step S9 , the print control unit 8 b executes the width position correction process on the second reference test image.

[0141] That is, the print control unit 8 b corrects the position of the second reference test image in the width direction D2 based on the reference center position SC1 based on the difference between the sheet center position PC1 at the center of the pair of second lateral edge positions obtained in step S8 and the reference center position SC1 .

[0142] The print control unit 8 b sets the image whose position in the width direction D2 is corrected by the width position correction process as the second test image G2 .

[0143] The plurality of line segment images G21 include a reference line segment image G210 (see Figure 6 ). The reference line segment image G210 is one located at the center in the width direction D2 among the plurality of line segment images G21.

[0144] In the second reference test image, the reference line segment image G210 is located at the reference center position SC1. On the other hand, in the second test image G2 obtained by the width position correction process, the reference line segment image G210 is located at the sheet center position PC1 (refer to Figure 6 ).

[0145] That is, the plurality of line segment images G21 corresponding to the reference image data supplied to the image processing circuit 53 in step S9 are arranged at equal intervals of the second length L2 in the width direction D2 with reference to the sheet center position PC1 that is the center of the pair of second lateral edge positions.

[0146] After executing the process of step S9 , the print control unit 8 b shifts the process to step S10 .

[0147] <Step S10> In step S10, the correction unit 8c obtains information of a test interference position from the image processing circuit 53. The test interference position is the interference position determined by the image processing circuit 53 based on the shielding region corresponding to the second transport process and the data of the second test image G2.

[0148] As described above, the masked area corresponding to the second conveying process is the area of ​​the plurality of black patch images G11 in the first test image G1. Therefore, the test interference position is the position where a part of the plurality of black patch images G11 interferes with a part of the plurality of line segment images G21.

[0149] In this embodiment, the correction unit 8c obtains the target test interference position Px1 from the image processing circuit 53. The target test interference position Px1 is the test interference position on the most downstream side in the conveying direction D1 (see Figure 7 ).

[0150] When the reference center position SC1 coincides with the print center position, the position where the reference black patch image G110 and the reference line segment image G210 interfere with each other is determined as the object test interference position Px1 (refer to Figure 6 ).

[0151] However, when the reference center position SC1 is offset toward the first side in the width direction D2 relative to the printing center position, the first test image G1 is formed at a position offset toward the second side in the width direction D2 than the reference black patch image G110 and the reference line segment image G210 interfere with each other.

[0152] Similarly, when the reference center position SC1 is offset toward the second side in the width direction D2 relative to the print center position, the first test image G1 is formed at a position offset toward the first side in the width direction D2 than the state where the reference black patch image G110 interferes with the reference line segment image G210 .

[0153] exist Figure 7In the example shown, the object test interference position Px1 is a position where one of the second positions among the plurality of black patch images G11 arranged on the first side of the width direction D2 relative to the reference black patch image G110 interferes with one of the second positions among the plurality of line segment images G21 arranged on the right side of the width direction D2 relative to the reference line segment image G210.

[0154] In this embodiment, the difference between the first length L1 and the second length L2 is the length of one pixel. Figure 7 An example is shown in which the reference center position SC1 is shifted by two pixels to the left in the width direction D2 relative to the printing center position.

[0155] That is, the correction unit 8 c can derive the direction and magnitude of the deviation of the reference center position SC1 from the print center position by identifying which of the plurality of line segment images G21 the target test interference position Px1 corresponds to.

[0156] After executing the process of step S10 , the correction unit 8 c shifts the process to step S11 .

[0157] <Step S11> In step S11 , the correction unit 8 c corrects the reference center position SC1 based on the target test interference position Px1 , and sets the corrected reference center position SC1 as a new reference center position SC1 .

[0158] Specifically, the plurality of line segment images G21 are assigned a plurality of identification values ​​that increase by 1 in the order of arrangement from the first side to the second side in the width direction D2. The value corresponding to the reference line segment image G210 is 0 among the plurality of identification values.

[0159] When the number of line segment images G21 is (2N+1), the plurality of identification values ​​are integers from -N to +N. Figure 7 In the example shown, the value corresponding to the target test interference position Px1 among the plurality of identification values ​​is -2.

[0160] In step S11 , the correction unit 8 c determines the value corresponding to the target test interference position Px1 among the plurality of identification values ​​as the number of correction pixels of the reference center position SC1 .

[0161] The reference center position SC1 is represented by the position of pixels in the width direction D2. The correction unit 8c determines the position after correcting the original reference center position SC1 by the correction number of pixels as a new reference center position SC1. The correction unit 8c records the information of the corrected reference center position SC1 in the auxiliary storage device 82.

[0162] After executing the process of step S11, the correction unit 8c ends the center position correction process. When the center position correction process ends, the main control unit 8a returns the operation mode from the correction mode to the normal mode.

[0163] When the operation mode is the normal mode, the print control unit 8b performs the width position correction process and the masking process for each sheet 9. In the width position correction process, the corrected reference center position SC1 is used. Furthermore, in the normal mode, the print control unit 8b causes the printing device 4 to perform a process of forming the print target image on which the width position correction process and the masking process are performed on the sheet 9.

[0164] By executing the center position correction process, the reference center position SC1 can be accurately set based on the test image formed on the target sheet 9 x without visually checking the image.

[0165] [Application Examples] Next, refer to Fig. 9 An application example of the image forming apparatus 10 will be described.

[0166] When the center position correction process is executed, power supply to the heater 431 of the drying device 43 is stopped. Furthermore, the processes after step S4 of the center position correction process are executed on the condition that the temperature of the drying device 43 satisfies the temperature permission condition.

[0167] However, in order to shorten the time of the adjustment process of the image forming apparatus 10 , it may be required to set the allowable temperature of the temperature allowable condition to a relatively high temperature. In this case, the target sheet 9 x may shrink due to the heat received from the heater 431 in the first conveyance process.

[0168] [Second Test Image Data Supply Process] Fig. 9 The flowchart shown shows Figure 8 This is an application example of the processing executed in step S9, that is, an example of the sequence of the second test image data supply processing.

[0169] In the following description, steps S91 to S93 represent identification codes of three steps of the second test image data supply process. In the second test image data supply process, the process of step S91 is first executed.

[0170] <Step S91> In step S91 , the correction unit 8 c derives the first sheet width and the second sheet width, and further derives a sheet width ratio which is a ratio of the second sheet width to the first sheet width.

[0171] The first sheet width is the distance between the first lateral edge positions obtained in step S5. The second sheet width is the distance between the second lateral edge positions obtained in step S8.

[0172] When the first conveying process is executed, if the target sheet 9 x shrinks due to passing through the drying device 43 , the sheet width ratio smaller than 1 is derived.

[0173] After executing the process of step S91, the correction unit 8c shifts the process to step S92.

[0174] In addition, when the sheet width ratio exceeds 1, the correction unit 8 c outputs an error notification and ends the second test image data supplying process and the center position correction process.

[0175] <Step S92> In step S92, the correction unit 8c corrects the second length L2 corresponding to the first length L1 by the sheet width ratio to derive the line interval. The line interval is the interval in the width direction D2 of the plurality of line segment images G21 in the second test image G2. The second length L2 is an example of a reference interval.

[0176] When the target sheet 9 x on which the first test image G1 is formed shrinks, the size of each black patch image G11 in the width direction D2 and the pitch of the plurality of black patch images G11 in the width direction D2 decrease according to the shrinkage rate of the target sheet 9 x.

[0177] The process of step S92 is a process of performing correction so that the intervals between the plurality of line segment images G21 in the width direction D2 match the size of the plurality of black patch images G11 in the width direction D2 .

[0178] After executing the process of step S92, the correction unit 8c shifts the process to step S93.

[0179] <Step S93> In step S93 , the correction unit 8 c generates data of a second test image G2 including a plurality of line segment images G21 arranged at the line intervals in the width direction D2 with reference to the center position of the pair of second lateral edge positions obtained in step S8 .

[0180] Furthermore, the correction unit 8 c supplies the data of the generated second test image G2 to the image processing circuit 53 as the reference image data.

[0181] After executing the process of step S93, the correction unit 8c ends the second test image data supply process. Next, the correction unit 8c executes the processes after step S10 (see Figure 8 ).

[0182] By executing the second test image data supplying process, the reference center position SC1 is corrected reflecting the sheet width ratio indicating the shrinkage rate of the target sheet 9 x caused by passing through the drying device 43 (see steps S10 and S11 ).

[0183] Therefore, by adopting this application example, it is possible to prevent the contraction of the target sheet 9 x due to passing through the drying device 43 from adversely affecting the correction of the reference center position SC1 .

[0184] By adopting this application example, even when the center position correction process is executed before the temperature of the drying device 43 drops to room temperature, it is possible to prevent the contraction of the target sheet 9 x from adversely affecting the correction of the reference center position SC1 .

[0185] The scope of the present invention is not limited to the above content, but is defined by the description of the claims, so it can be considered that the embodiments described in this specification are only illustrative, not limiting. Therefore, all changes that do not depart from the scope and limits of the claims, as well as contents that are equivalent to the scope and limits of the claims, are included in the scope of the claims.

Claims

1. An image formation control method, characterized in that: The image forming control method controls the image forming device. The image forming device comprises: A sheet conveying device conveys the sheet along the conveying passage; a printing device for forming an image on the sheet conveyed along the conveying path; a black reference member having a black reference surface, the reference surface being arranged along a width direction intersecting the sheet conveying direction in a state where it faces a detection area in the conveying path that is located upstream of the printing device in the sheet conveying direction; an image sensor unit arranged along the width direction in a state facing the reference surface with the detection area interposed therebetween, emitting detection light toward the reference surface and detecting the amount of light reflected from the detection light, and outputting a plurality of line image data, each of the plurality of line image data including information indicating the amount of detection light corresponding to a plurality of unit areas divided in the width direction in the detection area; and an image processing device for performing image processing based on the plurality of line image data, The image processing device is capable of executing area detection processing, the area detection processing is processing for detecting a pair of lateral edge positions, which are positions of both ends in the width direction of the sheet passing through the detection area, a sheet area, which is an area within a quadrilateral outline of the sheet, and a shielded area, which is a portion of the sheet area where the detected light amount is lower than a reference light amount. Furthermore, the image processing device is capable of executing interference position determination processing, which is processing for determining the position of an interference portion overlapping the shielding area in a reference image represented by the supplied reference image data. The image formation control method comprises: The processor causes the sheet conveying device to execute a first conveying process when the operation mode is the first mode, wherein the first conveying process is a process of conveying the target sheet in a state where a blank specific side of the target sheet becomes a printing side; The processor obtains information of a pair of the lateral edge positions, that is, a pair of first lateral edge positions, detected by the image processing device when the first conveying process is executed; When executing the first conveying process, the processor causes the printing device to execute a process of forming a first test image including a plurality of black patch images on the specific surface; the processor causing the sheet conveying device to execute a second conveying process, the second conveying process being a process of conveying the target sheet in a state where the specific surface on which the first test image is formed becomes a printing surface; The processor obtains information of a pair of the lateral edge positions, that is, a pair of second lateral edge positions, detected by the image processing device when the second conveying process is executed; The processor supplies data of a second test image including a plurality of line segment images corresponding to the plurality of black patch images and respectively extending along the sheet conveying direction as the reference image data to the image processing device, and obtains information of a test interference position, wherein the test interference position is the position of the interference portion determined by the image processing device based on the shielding area corresponding to the second conveying process and the data of the second test image; The processor sets the center position of the image sensor unit in the width direction, that is, the reference center position, according to the test interference position; The processor executes, when the operation mode is the second mode, a width position correction process, wherein the width position correction process is a process of correcting the position of the print target image in the width direction each time the sheet is conveyed, based on a difference between a center position of a pair of lateral edge positions detected by the image processing device each time the sheet is conveyed and the reference center position; The processor executes a masking process, wherein the masking process is a process of supplying the data of the printing target image on which the width position correction process is performed to the image processing device as the reference image data, and replacing pixels in the printing target image corresponding to the position of the interference portion determined by the image processing device with non-printing pixels; and the processor causes the printing device to execute a process of forming the print target image on the sheet to which the width position correction process and the mask process have been performed, The plurality of black patch images in the first test image are square black-painted images that are arranged in a step-like manner at intervals of a reference length in the width direction with the center of a pair of first lateral edge positions as a reference in a state where the positions are sequentially shifted in the sheet conveying direction, and each of the images has a width of the reference length. The multiple line segment images in the second test image are arranged at equal intervals less than the reference length in the width direction with the center position of a pair of the second lateral edge positions as a reference, and the ends of each of the multiple line segment images are formed at a position overlapping with a corresponding one of the multiple black patch images in the sheet conveying direction.

2. The image formation control method according to claim 1, characterized in that: The printing device forms an image on the sheet by ejecting ink onto the sheet. The image forming apparatus further includes a drying device, which is arranged on the downstream side of the sheet conveying direction relative to the printing device and has a heater for heating the sheet to dry the ink on the sheet. In this case, The image formation control method further includes: The processor corrects the reference interval corresponding to the reference length by the ratio of the interval between the pair of second lateral edge positions to the interval between the pair of first lateral edge positions, thereby deriving the interval in the width direction of the plurality of line segment images, i.e., the line interval. The processor generates data of the second test image including a plurality of the line segment images arranged at the line intervals in the width direction with reference to a center position of a pair of the second lateral edge positions.

3. The image formation control method according to claim 2, characterized in that: The image forming device further includes a temperature sensor, the temperature sensor detecting the temperature of the drying device, When the operation mode is the first mode, the processor causes the sheet conveying device to execute a process of conveying the target sheet on the condition that the temperature detected by the temperature sensor does not exceed a preset allowable temperature.

4. An image forming device, characterized in that: include: A sheet conveying device conveys the sheet along the conveying passage; a printing device for forming an image on the sheet conveyed along the conveying path; a black reference member having a black reference surface, the reference surface being arranged along a width direction intersecting the sheet conveying direction in a state where it faces a detection area in the conveying path that is located upstream of the printing device in the sheet conveying direction; an image sensor unit arranged along the width direction in a state facing the reference surface across the detection area, emitting detection light toward the reference surface and detecting the amount of light reflected from the detection light, and outputting a plurality of line image data, each of the plurality of line image data including detection light amounts corresponding to a plurality of unit areas divided in the width direction in the detection area; The image processing device can perform area detection processing by performing image processing based on the plurality of line image data, the area detection processing being processing for detecting a pair of lateral edge positions, a sheet area, and a shielded area, the pair of lateral edge positions being positions of both ends in the width direction of the sheet passing through the detection area, the sheet area being an area within the outline of a quadrilateral of the sheet, the shielded area being a portion of the sheet area where the detected light amount is lower than a reference light amount, and further, can perform interference position determination processing, the interference position determination processing being processing for determining the position of an interference portion overlapping the shielded area in a reference image represented by the supplied reference image data; and A processor implements the image formation control method according to claim 1 or 2.

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