Image forming control method and image forming apparatus

Abstract

The invention provides an image forming control method and an image forming apparatus, which can prevent the shrinkage of a sheet from having a bad influence on the correction of the central position of an edge detection part of a test image formed on the two surfaces of the sheet. The processor acquires a pair of first lateral edge positions when the first surface of the target sheet becomes a printing surface. The processor acquires a pair of second lateral edge positions when a second surface of the target sheet becomes a printing surface. The processor acquires coincidence scale information for specifying, from among a plurality of first scale images formed on the first surface of the target sheet, a coincidence scale image that coincides with one of a plurality of second scale images formed on the second surface of the target sheet in position in the width direction. The processor sets a reference center position according to a ratio of an interval between the pair of second lateral edge positions and an interval between the pair of first lateral edge positions and the coincident scale information.

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 according to a detection result of both end edge positions 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, that is, 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 based on the sheet center position.

[0004] Furthermore, it is known that in order to correct the deviation of the center position of the edge detection unit in the width direction, the image forming device forms a test image including a plurality of scale images on both sides of the sheet. At this time, the image forming device corrects the deviation of the center position of the edge detection unit according to the overlapping state of the plurality of scale images on both sides of the sheet when the sheet is viewed through.

[0005] Incidentally, the image forming apparatus may include a drying device that dries the ink image formed on the sheet by heating it.

[0006] When the test images are formed on both sides of the sheet, after the first test pattern is formed on the first side of the sheet, the sheet passes through the drying device, and after passing through the drying device, the sheet passes through the position of the edge detection unit, and a second test image is formed on the second side of the sheet.

[0007] When the temperature of the drying device is high, the sheet may shrink when passing through the drying device. Therefore, when the temperature of the drying device is high, the first test image is formed on the first surface of the sheet before shrinkage, and the second test image is formed on the second surface of the sheet after shrinkage.

[0008] The shrinkage of the sheet may adversely affect the deviation correction of the center position of the edge detection unit based on the test images formed on both surfaces of the sheet. Summary of the invention

[0009] An object of the present invention is to provide an image formation control method and an image forming apparatus which can prevent the shrinkage of a sheet due to passing through a drying device from adversely affecting the correction of the center position of an edge detection unit based on a test image formed on both sides of the sheet.

[0010] An image forming control method according to one embodiment 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 drying device, and an edge detection unit. The sheet conveying device conveys a sheet along a conveying path. The printing device forms an image on the sheet by ejecting ink onto the sheet conveyed along the conveying path. The drying device 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. The edge detection unit is arranged on the upstream side of the sheet conveying direction relative to the printing device, and detects a pair of lateral edge positions of the sheet, the pair of lateral edge positions being positions of both ends of the sheet in a width direction intersecting the sheet conveying direction. The image forming control method includes: when the operation mode is the first mode, the processor causes the sheet conveying device to perform a process of conveying the target sheet in a state where the first side of the target sheet becomes the printing side. The image formation control method includes: the processor obtains a pair of first lateral edge positions, the pair of first lateral edge positions being detection results of the edge detection unit when the target sheet is conveyed in a state where the first side of the target sheet becomes a printing side. The image formation control method includes: the processor causes the printing device to execute a process of forming a first test image on the first side of the target sheet with the center position of the pair of first lateral edge positions as a reference, the first test image including a plurality of first scale images arranged at a first interval in the width direction. The image formation control method includes: the processor causes the sheet conveying device to execute a process of conveying the target sheet in a state where the second side of the target sheet becomes a printing side. The image formation control method includes: the processor obtains a pair of second lateral edge positions, the pair of second lateral edge positions being detection results of the edge detection unit when the target sheet is conveyed in a state where the second side of the target sheet becomes a printing side. The image formation control method includes: the processor causes the printing device to execute a process of forming a second test image on the second side of the target sheet with the center position of the pair of second lateral edge positions as a reference, the second test image including a plurality of second scale images arranged at a second interval in the width direction. The image formation control method includes: the processor obtains consistent scale information, the consistent scale information is used to determine a consistent scale image that is consistent with one of the plurality of second scale images in the position in the width direction among the plurality of first scale images formed on the target sheet. The image formation control method includes: the processor sets a reference center position based on a sheet width ratio and the consistent scale information, the sheet width ratio being the ratio of the interval between the pair of second lateral edge positions to the interval between the pair of first lateral edge positions.The image formation control method includes: when the action mode is the second mode, the processor corrects the position of the print object image in the width direction based on the difference between the center position of the pair of lateral edge positions detected by the edge detection unit and the reference center position, and then causes the printing device to execute the process of forming the print object image on the sheet.

[0011] An image forming apparatus according to another aspect of the present invention includes the sheet conveying device, the printing device, the drying device, the edge detection unit, and the processor.

[0012] According to the present invention, an image formation control method and an image forming apparatus can be provided, which can prevent the shrinkage of a sheet due to passing through a drying device from adversely affecting the correction of the center position of an edge detection unit based on a test image formed on both sides of the sheet.

[0013] This specification introduces the concepts described in the following detailed description in a simplified manner with appropriate reference to the drawings. 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 objects described in the claims are 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

[0014] Figure 1 It is a block diagram of an image forming apparatus according to an embodiment.

[0015] Figure 2 This is a block diagram showing the configuration of a control device in the image forming apparatus according to the embodiment.

[0016] Figure 3 It is a top view of the edge sensor in the image forming apparatus according to the embodiment.

[0017] Figure 4 This is a diagram showing an example of a first surface of a target sheet on which a first test image is formed by the image forming apparatus according to the embodiment.

[0018] Figure 5 This is a diagram showing an example of the second surface of a target sheet on which a second test image is formed by the image forming apparatus according to the embodiment.

[0019] Figure 6 This is a partially enlarged view of the first surface of the target sheet on which the first test image is formed.

[0020] Figure 7 This is a flowchart showing an example of the procedure of the center position correction process in the image forming apparatus according to the embodiment. 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] (Configuration of Image Forming Apparatus 10) The image forming apparatus 10 according to the 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] A part of the plurality of conveying roller pairs 31 conveys the sheet 9 along the main conveying path 301 , and further sends the sheet 9 to the first belt conveyor device 32 .

[0025] The first belt conveyor 32 receives and 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 receives and conveys the sheet 9 from the first belt conveyor 32 and sends the sheet 9 to the subsequent conveying path 302.

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

[0027] In addition, some of the plurality of conveying roller pairs 31 also 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 for reversely conveying the sheet 9 in the reverse conveying path 303 and returning the sheet 9 to the main conveying path 301.

[0028] The main conveying path 301, the subsequent 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 in each of the first belt conveying device 32 and the second belt conveying device 33 are also a part of the conveying path of the sheet 9.

[0029] The printing device 4 executes a printing process for 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 the 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 ink heads 41 corresponding to inks of different colors and a plurality of ink supply units 42. Specifically, the printing device 4 includes four ink heads 41 and four ink supply units 42 corresponding to yellow, magenta, cyan, and black.

[0032] The plurality of ink heads 41 each have a plurality of nozzles 41 a for ejecting ink. The plurality of ink heads 41 are fixed at positions facing the conveyor belt 321 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 ink heads 41.

[0033] The first belt conveyor device 32 conveys the sheet 9 on which the image has been formed to the second belt conveyor device 33 .

[0034] The printing device 4 forms an image on the first surface of the sheet 9 when the sheet 9 is conveyed by the first belt conveyor 32 for the first time. The printing device 4 forms an image on the second surface of the sheet 9 when the sheet 9 passing through the reverse conveying path 303 is conveyed by the first belt conveyor 32 for the second time.

[0035] exist Figure 1 , Figure 3 to Figure 5 In the above, the conveying direction D1 is the sheet conveying direction. The sheet conveying direction is the direction in which the sheet conveying device 3 conveys the sheet 9. The width direction D2 is a direction intersecting the conveying direction D1. The width direction D2 is the main scanning direction in the above printing process, and the conveying direction D1 is the sub-scanning direction in the above printing process.

[0036] 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.

[0037] The drying device 43 has 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.

[0038] The drying device 43 further includes a fan 432. The fan 432 blows air heated by the heater 431 toward the sheet 9 on the second belt conveyor 33. The drying device 43 also includes a temperature sensor 430 for detecting the temperature inside the drying device 43.

[0039] The image forming apparatus 10 further includes an operating device 801, a display device 802, and a control device 8 (see Figure 1 ).

[0040] The operating device 801 detects human operation. For example, the operating device 801 includes a plurality of operating 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.

[0041] like Figure 2 As 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.

[0042] 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.

[0043] 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, the auxiliary storage device 82 can be a flash memory or a hard disk drive, or both.

[0044] The communication device 83 communicates with other devices such as the host device 7 through the network 70. The CPU 80 communicates with other devices through the communication device 83. The host device 7 is an information processing device that requests the image forming device 10 to perform the printing process.

[0045] 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 ).

[0046] The main control unit 8 a performs start control and the like for starting various processes in response to an operation on the operating device 801 or a process request received via the communication device 83 .

[0047] 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 .

[0048] The print control unit 8b controls the printer 4 to execute the printing process in synchronization with the conveyance of the sheet 9. 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 for the print target image.

[0049] The image forming apparatus 10 further includes an edge detection device 5 (see Figure 1 , Figure 3 ). The edge detection device 5 is arranged on the upstream side of the printing device 4 in the conveying direction D1.

[0050] The edge detection device 5 detects the positions of both ends of the sheet 9 in the width direction D2 conveyed by the sheet conveying device 3, that is, a pair of lateral edge positions E1 (see Figure 3 ). The edge detection device 5 is an example of an edge detection unit.

[0051] In this embodiment, the edge detection device 5 includes a line sensor 51, a line light source 52, and an edge detection circuit 53 (see Figure 1 , Figure 3 ).

[0052] The line sensor 51 and the line light source 52 are arranged along the width direction D2 (see Figure 3 ). The line sensor 51 and the line light source 52 are arranged relative to each other via the main conveying channel 301 (refer to Figure 1 ).

[0053] The line sensor 51 has a plurality of photoelectric conversion elements arranged in the width direction D2. The line sensor 51 outputs line data including a plurality of pixel data corresponding to a plurality of positions in the width direction D2. The plurality of pixel data represents the amount of light received by the plurality of photoelectric conversion elements.

[0054] When the sheet 9 passes through the detection area between the line sensor 51 and the line light source 52 , the sheet 9 blocks the light from the line light source 52 toward the line sensor 51 .

[0055] The edge detection circuit 53 is a device that realizes the processing of the line data by hardware. For example, the edge detection circuit 53 is composed of an ASIC (Application Specific Integrated Circuit) or a DSP (Digital Signal Processor).

[0056] The portion of the line sensor 51 corresponding to the width of the sheet 9 receives less light than other portions. The edge detection circuit 53 detects a pair of lateral edge positions E1 by performing edge detection processing on the line data.

[0057] In addition, the edge detection device 5 described above is a transmission type light detection device. On the other hand, the edge detection device 5 may also be a reflection type light detection device.

[0058] In the reflective light detection device, the line sensor 51 and the line light source 52 are arranged side by side on one side of the detection area. The reflective light detection device further includes a black reference member arranged to face the line sensor 51 via the detection area.

[0059] In the reflective light detection device, the portion of the line sensor 51 corresponding to the width of the sheet 9 receives more light than other portions. In the reflective light detection device, the edge detection circuit 53 also detects a pair of lateral edge positions E1 by edge detection processing on the line data.

[0060] In the image forming apparatus 10, the center position of the detection area in the width direction D2 is set as a reference center position SC1 (refer to Figure 3 ). The reference center position SC1 is a position corresponding to a specific one of the plurality of pixel data of the row data.

[0061] The reference center position SC1 corresponds to the center position in the width direction D2 of the printing width area, that is, the printing center position. The printing width area is an area in the width direction D2 where the printing device 4 can form an image.

[0062] 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 , Figure 5 The sheet center position PC1 is the center position in the width direction D2 of the sheet 9 passing through the detection area.

[0063] 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 the expected position in the width direction D2 .

[0064] The print control unit 8b executes a width position correction process each time a sheet 9 is conveyed. The width position correction process is a process for correcting the position of the print target image in the width direction D2 according to the position difference DX1 which is the difference between the sheet center position PC1 and the reference center position SC1 (see Figure 3 ).

[0065] After executing the width position correction process for each sheet 9 , the print control unit 8 b causes the printer 4 to execute the print process for the print target image whose position in the width direction D2 is corrected. Thus, the print target image is formed at an appropriate position in the width direction D2 on the sheet 9 .

[0066] However, when the reference center position SC1 in the edge detection device 5 is offset from the printing center position in the printing device 4 , the print target image is formed at a position offset in one direction in the width direction D2 on the sheet 9 .

[0067] 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 a center position correction process described later (see Figure 7The center position correction process is a process for correcting a deviation of the reference center position SC1 relative to the printing center position.

[0068] In the following description, the sheet 9 used for the center position correction process is referred to as a target sheet 9x (see Figure 4 , Figure 5 ).

[0069] In the center position correction process, the correction unit 8c causes the printing device 4 to execute a process of forming a first test image G1 on the first surface 9a of the target sheet 9x and a process of forming a second test image G2 on the second surface 9b of the target sheet 9x (see Figure 4 , Figure 5 ).

[0070] The first test image G1 includes a plurality of first scale images G11 arranged at a first interval P1 in the width direction D2 (see Figure 4 ). Furthermore, the first test image G1 includes a plurality of identification value images G12 corresponding to the plurality of first scale images G11.

[0071] The second test image G2 includes a plurality of second scale images G21 arranged at a second interval P2 in the width direction D2 (see Figure 5 ). The second interval P2 is larger than the first interval P1 by 1 pixel.

[0072] The plurality of identification value images G12 are images respectively representing values ​​for identifying the plurality of first scale images G11 .

[0073] As described later, the correction unit 8 c corrects the deviation of the reference center position SC1 based on the overlapping state of the plurality of scale images G11 and G21 on both surfaces of the target sheet 9 x when the target sheet 9 x is seen through.

[0074] However, the image forming apparatus 10 includes a drying device 43 that dries the ink image formed on the sheet 9 by heating it.

[0075] When the first test image G1 and the second test image G2 are formed on the target sheet 9x, after the first test image G1 is formed on the first surface 9a of the target sheet 9x, the target sheet 9x passes through the drying device 43. After passing through the drying device 43, the target sheet 9x passes through the position of the edge detection device 5, and the second test image G2 is formed on the second surface 9b of the target sheet 9x.

[0076] When the temperature of the drying device 43 is high, the target sheet 9x may shrink when passing through the drying device 43. Therefore, when the temperature of the drying device 43 is high, the first test image G1 is formed on the first surface 9a of the target sheet 9x before shrinkage, and the second test image G2 is formed on the second surface 9b of the target sheet 9x after shrinkage.

[0077] The contraction of the target sheet 9 x has an adverse effect on the correction of the deviation of the reference center position SC1 of the first test image G1 and the second test image G2 formed on both surfaces of the target sheet 9 x.

[0078] The center position correction process in the present embodiment includes a process for preventing 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 .

[0079] In the present embodiment, when the operation device 801 detects a correction start operation, 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.

[0080] The center position correction process is executed when the operation mode is the correction mode. When the center position correction process is completed, the main control unit 8a returns the operation mode from the correction mode to the normal mode.

[0081] When the operation mode is the normal mode, the print control unit 8 b executes the width position correction process for each sheet 9 and then causes the printing device 4 to execute the print process for the print target image whose position in the width direction D2 is corrected.

[0082] The calibration mode is an example of the first mode, and the normal mode is an example of the second mode.

[0083] (Center position correction processing) Below, refer to Figure 7 The flowchart shown in FIG. 1 illustrates an example of the procedure of the center position correction process.

[0084] 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.

[0085] In the following description, S1, S2, ... represent identification marks of a plurality of steps in the center position correction process. In the center position correction process, the process of step S1 is first executed.

[0086] <Process S1> In step S1 , the print control unit 8 b performs control to stop the power supply to the heater 431 of the drying device 43 .

[0087] After executing the process of step S1, the print control unit 8b transfers 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.

[0088] <Process S2> In step S2 , the correction unit 8 c determines whether the image forming apparatus 10 is in a permitted state satisfying a predetermined permitted condition or in a non-permitted state not satisfying the permitted condition.

[0089] In the present embodiment, the permissible conditions include a temperature permissible condition regarding the temperature of the drying device 43 and a thickness permissible condition regarding the thickness of the target sheet 9 x .

[0090] The temperature permissible condition is a condition that the temperature detected by the temperature sensor 430 of the drying device 43 does not exceed a preset permissible temperature. In step S2, the calibration unit 8c obtains the temperature detected by the temperature sensor 430 and determines whether the detected temperature satisfies or does not satisfy the temperature permissible condition.

[0091] The thickness tolerance condition is a condition that the thickness information representing the thickness of the target sheet 9x does not exceed a preset tolerance thickness. In step S2, the calibration unit 8c obtains the thickness information stored in the auxiliary storage device 82 and determines whether the thickness information satisfies or does not satisfy the thickness tolerance condition.

[0092] The thickness information is stored in the auxiliary storage device 82 in a state corresponding to the sheet storage unit 1. The correction unit 8c acquires the thickness information corresponding to the sheet storage unit 1 which is the supply source of the target sheet 9x from the auxiliary storage device 82.

[0093] For example, the thickness information is information representing the weight of the target sheet 9 x , and the allowable thickness is a preset allowable upper limit value of the weight of the target sheet 9 x .

[0094] The temperature permissible condition is determined to prevent the target sheet 9x from shrinking too much when the target sheet 9x passes through the drying device 43. The thickness permissible condition is determined to prevent the second test image G2 from being unable to be visually recognized from the first surface 9a side of the target sheet 9x when the target sheet 9x is seen through.

[0095] The correction unit 8c determines that the image forming apparatus 10 is in the permissible state when both the temperature permissible condition and the thickness permissible condition are satisfied. On the other hand, the correction unit 8c determines that the image forming apparatus 10 is in the non-permissible state when at least one of the temperature permissible condition and the thickness permissible condition is not satisfied.

[0096] When the correction unit 8c determines that the image forming apparatus 10 is in the non-permitted state, the correction unit 8c transfers the process to step S3. On the other hand, when the correction unit 8c determines that the image forming apparatus 10 is in the permitted state, the correction unit 8c transfers the process to step S4.

[0097] <Process S3> In step S3 , the correction unit 8 c performs error notification and notifies predetermined error information via the display device 802 .

[0098] For example, the error information is information indicating that the image forming apparatus 10 is in a state that does not satisfy the permissible condition and the processing that the user should perform in order to make the image forming apparatus 10 satisfy the permissible condition.

[0099] After executing the process of step S3, the correction unit 8c ends the center position correction process. Alternatively, the correction unit 8c may repeat the processes of step S2 and step S3 until the image forming apparatus 10 reaches a state satisfying the permission condition.

[0100] When the temperature detected by the temperature sensor 430 does not satisfy the temperature tolerance condition, the print control unit 8b may stop supplying power to the heater 431 of the drying device 43 and operate the fan 432. In this way, the cooling of the drying device 43 is accelerated.

[0101] The processing after step S4 described below is performed under the condition that both the temperature allowable condition and the thickness allowable condition are satisfied.

[0102] <Step S4> In step S4 , the print control unit 8 b causes the sheet conveying device 3 to execute the first conveying process to convey the target sheet 9 x with the first surface 9 a of the target sheet 9 x serving as the printing surface.

[0103] When the first transport process is executed, the processes of step S5 and step S6 are executed.

[0104] <Step S5> In step S5, the correction unit 8c obtains data of a pair of first lateral edge positions from the edge detection device 5 when the target sheet 9x passes through the detection area. The pair of first lateral edge positions are the detection results of the edge detection device 5 when the target sheet 9x is conveyed with the first surface 9a of the target sheet 9x as the printing surface.

[0105] After executing the process of step S5 , the correction unit 8 c shifts the process to step S6 .

[0106] <Step S6> In step S6 , the print control unit 8 b causes the printing device 4 to execute a process of forming the first test image G1 on the first surface 9 a of the target sheet 9 x .

[0107] In step S6 , the print control unit 8 b performs the width position correction process on the first test image G1 including a plurality of first scale images G11 arranged at the first interval P1 in the width direction D2 , with reference to the preset reference center position SC1 .

[0108] That is, the print control unit 8 b corrects the position in the width direction D2 of the first test image G1 based on the reference center position SC1 , based on the difference between the center position of the pair of first lateral edge positions obtained in step S5 and the reference center position SC1 .

[0109] The plurality of first scale images G11 include a first reference scale image G110 (see Figure 4 ). The first reference scale image G110 is one of the plurality of first scale images G11 located at the center in the width direction D2.

[0110] In the first test image G1 before the width position correction process is performed, the first reference scale image G110 is located at the reference center position SC1.

[0111] In step S6 , the print control unit 8 b causes the printing device 4 to execute a process of forming the first test image G1 after the width position correction process has been performed on the first surface 9 a of the target sheet 9 x .

[0112] In the first test image G1 after the width position correction process, the first reference scale image G110 is located at the sheet center position PC1 corresponding to the pair of first lateral edge positions. The sheet center position PC1 corresponding to the pair of first lateral edge positions is the center position of the pair of first lateral edge positions.

[0113] That is, in step S6 , the print control unit 8 b causes the printing device 4 to execute processing to form a first test image G1 including a plurality of first scale images G11 arranged at the first interval P1 in the width direction D2 with reference to the center position of the pair of first lateral edge positions.

[0114] After executing the process of step S6 , the print control unit 8 b shifts the process to step S7 .

[0115] <Step S7> In step S7 , the print control unit 8 b causes the sheet conveying device 3 to execute the second conveying process to convey the target sheet 9 x with the second surface 9 b of the target sheet 9 x serving as the printing surface.

[0116] In the present embodiment, the sheet conveying device 3 can automatically execute the second conveying process after the first conveying process by reversely conveying the target sheet 9 x on which the first test image G1 is formed.

[0117] When the sheet conveying device 3 does not have a reverse conveying mechanism, in step S7, the main control unit 8a notifies the target sheet setting information through the display device 802. The target sheet setting information is information for urging the target sheet 9x to be set in the sheet storage unit 1 so that the second surface 9b of the target sheet 9x becomes the printing surface.

[0118] When the operation device 801 detects the conveyance start operation corresponding to the target sheet setting information, the print control unit 8 b causes the sheet conveyance device 3 to execute the second conveyance process for the target sheet 9 x set in the sheet storage unit 1 .

[0119] When the second transport process is executed, the processes of step S8 and step S9 are executed.

[0120] <Step S8> In step S8, the correction unit 8c obtains data of a pair of second lateral edge positions from the edge detection device 5 when the target sheet 9x passes through the detection area. The pair of second lateral edge positions are the detection results of the edge detection device 5 when the target sheet 9x is conveyed with the second surface 9b of the target sheet 9x serving as the printing surface.

[0121] After executing the process of step S8 , the correction unit 8 c shifts the process to step S9 .

[0122] <Step S9> In step S9 , the print control unit 8 b causes the printing device 4 to execute a process of forming the second test image G2 on the second surface 9 b of the target sheet 9 x .

[0123] In step S9 , the print control unit 8 b performs the width position correction process on the second test image G2 including the plurality of second scale images G21 arranged at the second interval P2 in the width direction D2 , with reference to the preset reference center position SC1 .

[0124] That is, the print control unit 8 b corrects the position in the width direction D2 of the second test image G2 based on the reference center position SC1 , based on the difference between the center position of the pair of second lateral edge positions obtained in step S8 and the reference center position SC1 .

[0125] The plurality of second scale images G21 include a second reference scale image G210 (see Figure 5 ). The second reference scale image G210 is one of the plurality of second scale images G21 located at the center in the width direction D2.

[0126] In the second test image G2 before the width position correction process is performed, the second reference scale image G210 is located at the reference center position SC1.

[0127] In step S9 , the print control unit 8 b causes the printing device 4 to execute a process of forming the second test image G2 after the width position correction process has been performed on the second surface 9 b of the target sheet 9 x .

[0128] In the second test image G2 after the width position correction process, the second reference scale image G210 is located at the sheet center position PC1 corresponding to the pair of second lateral edge positions. The sheet center position PC1 corresponding to the pair of second lateral edge positions is the center position of the pair of second lateral edge positions.

[0129] That is, in step S9 , the print control unit 8 b causes the printing device 4 to execute processing to form a second test image G2 including a plurality of second scale images G21 arranged at the second interval P2 in the width direction D2 with reference to the center position of the pair of second lateral edge positions.

[0130] After executing the process of step S9 , the print control unit 8 b shifts the process to step S10 .

[0131] <Step S10> In step S10 , the calibration unit 8 c executes a process of acquiring a coincident scale value.

[0132] The coincident scale value is a numerical value for specifying a coincident scale image G10 that coincides with one of the plurality of second scale images G21 in the width direction D2 among the plurality of first scale images G11 formed on the target sheet 9x (see Figure 6 ).

[0133] In the present embodiment, the coincidence scale value is a numerical value representing a specific identification value image G120 corresponding to the coincidence scale image G10 among the plurality of identification value images G12. The coincidence scale value is an example of coincidence scale information.

[0134] like Figure 4 As shown, the plurality of numerical values ​​represented by the plurality of identification value images G12 are numerical values ​​that increase one by one from the first side to the second side in the width direction D2 , and the numerical value corresponding to the first reference scale image G110 is 0.

[0135] exist Figure 4 In the example of , 41 first scale images G11 are arranged at a first interval P1 in the width direction D2. Also, 41 identification value images G12 correspond to the 41 first scale images G11 and represent integers from -20 to +20 arranged in sequence from the first side to the second side in the width direction D2.

[0136] exist Figure 6 In the example of , the consistent scale image G10 is the fourth scale image toward the second side based on the first reference scale image G110 among the plurality of first scale images G11. At this time, the consistent scale value is 4.

[0137] In step S10 , the correction unit 8 c notifies the user of predetermined see-through request information via the display device 802 .

[0138] The see-through request information includes information for requesting that the coincident scale image G10 be determined by see-through the target sheet 9 x from the first surface 9 a side.

[0139] Furthermore, the see-through request information includes information for requesting the operation device 801 to input a numerical value representing the specific identification value image G120 corresponding to the matching scale image G10.

[0140] The correction unit 8c acquires the numerical value input to the operation device 801 in response to the notification of the fluoroscopy request information as the coincidence scale value.

[0141] The plurality of identification value images G12 may be, for example, images representing a plurality of symbols, etc. In this case, the correction unit 8c converts the symbols obtained in step S10 into numerical values ​​according to a preset conversion table.

[0142] After executing the process of step S10 , the correction unit 8 c shifts the process to step S11 .

[0143] <Step S11> In step S11 , 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.

[0144] The first sheet width is the distance between the pair of first lateral edge positions obtained in step S5 . The second sheet width is the distance between the pair of second lateral edge positions obtained in step S8 .

[0145] When the target sheet 9 x is shrunk by passing through the drying device 43 during the execution of the first conveyance process, the sheet width ratio smaller than 1 is derived.

[0146] After executing the process of step S11, the correction unit 8c shifts the process to step S12.

[0147] <Step S12> In step S12 , the correction unit 8 c corrects the reference center position SC1 based on the sheet width ratio and the coincidence scale value, and sets the corrected reference center position SC1 as a new reference center position SC1 .

[0148] Specifically, the correction unit 8 c substitutes the coincidence scale value X and the sheet width ratio R into the following formula (1) to derive the correction pixel number Y of the reference center position SC1 . In the formula (1), P is the first interval P1 .

[0149] The reference center position SC1 is expressed as a pixel position in the width direction D2. The correction unit 8c sets the position after correcting the original reference center position SC1 by the correction pixel number 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.

[0150] In addition, the formula (1) is adopted when the second interval P2 is larger than the first interval P1 by 1 pixel.

[0151] After executing the process of step S12, 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.

[0152] When the operation mode is the normal mode, the print control unit 8b causes the printer 4 to execute the printing process for the print target image whose position in the width direction D2 is corrected after executing the width position correction process for each sheet 9. In the width position correction process, the corrected reference center position SC1 is used.

[0153] By executing the center position correction process, the reference center position SC1 is corrected reflecting the sheet width ratio (see step S12 ) that represents the shrinkage rate of the target sheet 9 x caused by passing through the drying device 43 .

[0154] Therefore, by adopting the above-described center position correction process, it is prevented that the contraction of the target sheet 9 x due to passing through the drying device 43 has an adverse effect on the correction of the reference center position SC1 .

[0155] According to the image forming apparatus 10 , 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 .

[0156] The scope of the present invention is not limited to the above content, but is defined by the description of the claims, so 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 forming control method for controlling an image forming device, the image forming device comprising: A sheet conveying device conveys the sheet along the conveying passage; a printing device for forming an image on the sheet by ejecting ink onto the sheet conveyed along the conveying path; a drying device, arranged on the downstream side of the sheet conveying direction relative to the printing device, and having a heater for heating the sheet to dry the ink on the sheet; as well as The edge detection unit is arranged on the upstream side of the sheet conveying direction relative to the printing device, and detects a pair of lateral edge positions of the sheet, the pair of lateral edge positions being positions of both ends of the sheet in the width direction intersecting the sheet conveying direction. The image formation control method is characterized by comprising: The processor causes the sheet conveying device to execute processing of conveying the target sheet with the first side of the target sheet serving as a printing side when the operation mode is the first mode; The processor obtains a pair of first lateral edge positions, which are detection results of the edge detection unit when the target sheet is conveyed in a state where the first surface of the target sheet becomes a printing surface; The processor causes the printing device to execute a process of forming a first test image on the first side of the target sheet with the center position of the pair of first lateral edge positions as a reference, the first test image including a plurality of first scale images arranged at first intervals in the width direction; The processor causes the sheet conveying device to execute a process of conveying the target sheet in a state where the second surface of the target sheet becomes a printing surface; The processor obtains a pair of second lateral edge positions, the pair of second lateral edge positions being detection results of the edge detection unit when the target sheet is conveyed in a state where the second surface of the target sheet becomes a printing surface; The processor causes the printing device to execute a process of forming a second test image on the second side of the target sheet with the center position of the pair of second lateral edge positions as a reference, the second test image including a plurality of second scale images arranged at second intervals in the width direction; The processor acquires coincident scale information for identifying one of the plurality of first scale images formed on the target sheet, the first scale image being coincident with one of the plurality of second scale images in position in the width direction; The processor sets a reference center position according to a sheet width ratio and the coincidence scale information, wherein the sheet width ratio is a ratio of an interval between the pair of second lateral edge positions to an interval between the pair of first lateral edge positions; When the action mode is the second mode, the processor corrects the position of the print object image in the width direction based on the difference between the center position of the pair of lateral edge positions detected by the edge detection unit and the reference center position, and then causes the printing device to execute the processing of forming the print object image on the sheet.

2. The image formation control method according to claim 1, characterized in that: The processor also executes control to stop supplying power to the heater of the drying device when the operation mode is the first mode.

3. The image formation control method according to claim 1 or 2, characterized in that: The image forming device further includes a temperature sensor for 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. The image formation control method according to claim 1 or 2, characterized in that: The processor further includes obtaining thickness information representing the thickness of the target sheet when the operation mode is the first mode, 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 condition that the thickness information satisfies a preset permission condition.

5. 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 by ejecting ink onto the sheet conveyed along the conveying path; a drying device, arranged on the downstream side of the sheet conveying direction relative to the printing device, and having a heater for heating the sheet to dry the ink on the sheet; an edge detection unit, arranged on an upstream side of the sheet conveying direction relative to the printing device, and detecting a pair of lateral edge positions of the sheet, the pair of lateral edge positions being positions of both ends of the sheet in a width direction intersecting the sheet conveying direction; and A processor implements the image formation control method described in claim 1 or claim 2.

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