Image forming system

Abstract

To provide an image forming system that can prevent increase in the number of sheets determined to be abnormal.SOLUTION: An image forming system comprises: a printer 100 that prints an image on a sheet; an inspection device 150 that can perform inspection of the sheet on which the image is printed by the printer 100 at a plurality of different inspection levels; and a CPU 131. The CPU 131 performs adjustment of quality of the image printed by the printer 100. The CPU 131 determines an adjustment frequency of performing the adjustment according to the inspection level. The CPU 131 performs the adjustment on the basis of the adjustment frequency.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an image forming system equipped with an inspection device that inspects (inspects) a sheet (deliverable product) on which an image is printed. [Background technology]

[0002] It is known that image forming apparatuses conventionally perform an adjustment operation at predetermined time intervals to change image formation conditions based on the results of reading an adjustment chart. The adjustment chart is a sheet on which an image for adjusting the image formation conditions is formed. By performing the adjustment operation, the image forming apparatus can suppress variations in print position and color tone caused by changes over time in components and materials used, such as toner. Furthermore, a technology has been proposed in the past in which an inspection device reads an image formed on a sheet and inspects (inspects) the image (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2022-90999 Summary of the Invention [Problem to be solved by the invention]

[0004] The inspection device allows the user to set the inspection level when performing inspection. However, if the amount of fluctuation in print position, color, etc. increases due to the above-mentioned changes over time, the images formed by the image forming device may no longer meet the inspection level set by the user. In other words, if a certain amount of time has passed since the above-mentioned adjustment operation was performed, the number of sheets determined to be abnormal may increase.

[0005] SUMMARY OF THE INVENTION In view of the above-mentioned problems, a main object of the present invention is to provide an image forming system that can prevent an increase in the number of sheets that are determined to be abnormal. [Means for solving the problem]

[0006] The image forming system of the present invention comprises a printing means for printing an image on a sheet, an inspection means for inspecting the image formed on the sheet based on an inspection level set from among a plurality of inspection levels, an adjustment means for adjusting the image forming conditions of the printing means, and a control means for, when a first inspection level is set, causing the adjustment means to adjust the image forming conditions when an image has been formed on a first number of sheets by the printing means, and for, when a second inspection level is set, causing the adjustment means to adjust the image forming conditions when an image has been formed on a second number of sheets by the printing means; when the inspection level is changed to the second inspection level before images are formed on the first number of sheets at the first inspection level, if the number of sheets on which images are formed at the first inspection level is equal to or greater than the second number, the control means causes the adjustment means to perform the adjustment; The second inspection level is higher than the first inspection level, and the second number is less than the first number. Another image forming system of the present invention comprises a printing means for printing an image on a sheet; an inspection means for inspecting the image formed on the sheet based on an inspection level set from among a plurality of inspection levels; an adjustment means for adjusting the image formation conditions of the printing means; a control means for, when a first inspection level is set, causing the adjustment means to adjust the image formation conditions when an image is formed on a first number of sheets by the printing means, and, when a second inspection level is set, causing the adjustment means to adjust the image formation conditions when an image is formed on a second number of sheets by the printing means; and a counter for counting the number of sheets on which an image is formed by the printing means, wherein the control means clears the number of sheets counted by the counter when the adjustment means makes the adjustment before images are formed on the first number of sheets at the first inspection level, and clears the number of sheets counted by the counter when the adjustment means makes the adjustment before images are formed on the second number of sheets at the second inspection level, and the second inspection level is a higher inspection level than the first inspection level, and the second number is less than the first number. Another image forming system of the present invention includes a printing means for printing an image on a sheet, an inspection means for inspecting the image formed on the sheet based on an inspection level set from among a plurality of inspection levels, an adjustment means for adjusting image forming conditions of the printing means, a control means for causing the adjustment means to adjust the image forming conditions when an image is formed on a first number of sheets by the printing means when a first inspection level is set, and for causing the adjustment means to adjust the image forming conditions when an image is formed on a second number of sheets by the printing means when a second inspection level is set, a display means for displaying an inspection setting screen for setting the inspection level, and an input means for inputting information on the inspection level set on the inspection setting screen. the inspection means notifies the control means of the inspection level set by the information input by the input means, and when the control means is notified of the first inspection level from the inspection means, the control means determines the first number of sheets as the interval for performing the adjustment, and when the control means is notified of the second inspection level, the control means determines the second number of sheets as the interval for performing the adjustment, the input means can set the inspection level for each area on the inspection setting screen, and the control means determines the number of sheets indicating the interval for performing the adjustment based on the highest inspection level among the inspection levels for each area, the second inspection level being higher than the first inspection level, and the second number of sheets being less than the first number. [Effects of the Invention]

[0007] According to the present invention, it is possible to prevent an increase in the number of sheets determined to be abnormal. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram of an image forming system. [Figure 2] FIG. [Figure 3] FIG. 2 is a diagram illustrating the configuration of a printer engine. [Figure 4] CIS unit configuration diagram. [Figure 5] An explanatory diagram of inspection. [Figure 6] FIG. 10 is a diagram illustrating an example of an examination setting screen. [Figure 7] FIG. 10 is an explanatory diagram of an adjustment image for correcting color misregistration. [Figure 8] FIG. 10 is an explanatory diagram of an adjustment image for tone density correction. [Figure 9] FIG. 10 is a diagram illustrating an example of a print position adjustment chart. [Figure 10]5A to 5G are diagrams illustrating a method for calculating the amount of print position deviation. [Figure 11] FIG. 4 is a sequence diagram showing the exchange of information during printing processing and inspection processing. [Figure 12] 1 is an explanatory diagram of image quality characteristics. [Figure 13] 10 is an explanatory diagram of the number of printed sheets and the guaranteed color quality of the image. [Figure 14] FIG. 10 is an explanatory diagram of the frequency of toner gradation density correction according to the inspection level. [Figure 15] 10 is a flowchart showing a process for determining a threshold value for an adjustment frequency according to an inspection level. [Figure 16] 10 is a flowchart illustrating an image forming process including an adjustment operation execution determination process. [Figure 17] FIG. 4 is a sequence diagram showing the exchange of information during printing processing and inspection processing. [Figure 18] 10 is a flowchart showing an adjusting operation execution determination process. [Figure 19] FIG. [Figure 20] FIG. [Figure 21] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[0010] (Image forming system) 1 is an explanatory diagram of the image forming system of this embodiment. Unless otherwise specified, it goes without saying that the present invention can be applied to a system configured and processing is performed via a network, as long as the functions of the present invention are realized.

[0011] The image forming system 1 of this embodiment is configured to include a printing device 100, which is an image forming device, an inspection device 150, and a host computer 101, which is an external device. The printing device 100 and the inspection device 150 can communicate with the host computer 101 via a communication line 105. The communication line 105 is, for example, a local area network (LAN), a wide area network (WAN), a public communication line, etc. The communication line 105 may also be configured using a serial interface such as a universal serial bus (USB), or a parallel interface. Note that at least one of the host computer 101 and the set of the printing device 100 and the inspection device 150 may be provided in plurality on the communication line 105.

[0012] The host computer 101 has a user interface (not shown) and generates a print job based on input information acquired from the user interface. The host computer 101 transmits the generated print job to the printing device 100 via a communication line 105. The print job includes instructions, settings, image data, etc. for causing the printing device 100 to perform printing processing.

[0013] The printing device 100 includes a controller 110 and a printer engine 130. The controller 110 performs various processes and controls the operation of the printing device 100. Here, a configuration in which the controller 110 is built into the printing device 100 will be described, but the controller 110 may also be configured as a device that is independent of the printing device 100 and can communicate with the printing device 100.

[0014] The controller 110 includes a CPU (Central Processing Unit) 111, a ROM (Read Only Memory) 112, a RAM (Random Access Memory) 113, and storage 114. The controller 110 also includes, as communication interfaces, a network interface (I / F) 115, a communication port 116, and a printer communication I / F 117. The controller 110 also includes an operation panel 120, which is a user interface. These components are connected to each other via a system bus so that they can communicate with each other.

[0015] The operation panel 120 has an input interface and an output interface. The input interface is, for example, various key buttons and a touch panel. The output interface is, for example, a display 120a and a speaker. The controller 110 receives various operation instructions and settings from the operation panel 120 through user operation. The controller 110 also displays information about the image forming system 1, the printing status, a setting screen, etc. on the display 120a of the operation panel 120.

[0016] The ROM 112 is a non-volatile storage device that stores a startup program and the like. The storage 114 is a large-capacity storage device that temporarily or long-term stores large amounts of data such as control programs, image data, and various setting data. The storage 114 may be, for example, a hard disk drive (HDD) or a solid state drive (SSD). The CPU 111 performs startup processing for the printing device 100 by executing the startup program stored in the ROM 112 at startup. After startup of the printing device 100, the CPU 111 controls operations such as printing processing by the printing device 100 by executing the control program stored in the storage 114. The RAM 113 provides a working area for the CPU 111 when performing various processes.

[0017] The communication port 116 controls communication with the inspection device 150. The CPU 111 transmits signals and the like for controlling the operation of the inspection device 150 via the communication port 116. The CPU 111 acquires inspection results from the inspection device 150 via the communication port 116. The printer communication I / F 117 controls communication with the printer engine 130. The CPU 111 transmits various signals for controlling the operation of the printer engine 130 via the printer communication I / F 117. The network I / F 115 controls communication between the host computer 101 and the inspection device 150 via the communication line 105. The network I / F 115 transmits data acquired via the communication line 105 to the CPU 111, and also transmits data via the communication line 105 in response to an instruction from the CPU 111.

[0018] With this configuration, the CPU 111 decodes a print job acquired from the host computer 101 via the network I / F 115 and generates image data for each page. The CPU 111 converts the generated image data into raster image data for each line. The CPU 111 transmits the raster image data to the printer engine 130 via the printer communication I / F 117 and causes the printer engine 130 to form an image.

[0019] The printer engine 130 prints raster image data generated from a print job as a visible image on a printing sheet under the control of the controller 110. The printer engine 130 includes a CPU 131, a ROM 132, a RAM 133, a controller communication I / F 134, a camera unit 135, a timer 136, an I / O port 137, and an AD converter 138.

[0020] The CPU 131 controls the printer engine 130 by executing a computer program stored in the ROM 132. The RAM 133 provides a work area for the CPU 131 when it executes processing. The controller communication I / F 134 controls communication with the printer communication I / F 117 of the controller 110. The camera unit 135 reads a sheet (a deliverable) on which an image is printed.

[0021] The timer 136 measures the time of an input signal with high precision and is capable of outputting a periodic signal with high precision. The I / O port 137 has an input port that detects the signal logic of the printer engine 130 and an output port that can output the logic of the output signal in binary form. The AD converter 138 converts the voltage value (detection value) of the sensor in the printer engine 130, the primary transfer voltage, primary transfer current, and current value of the density detection sensor described below, and the detection signal of the CIS unit described below, into digital values ​​and inputs them to the CPU 131. The communication I / F 139 controls communication with the inspection device 150 via serial communication. The communication I / F 139 transmits detection information of the CIS described below, etc. to the inspection device 150.

[0022] The inspection device 150 is capable of communicating with the controller 110 via a communication line 105, and is also capable of communicating via a communication port 116. The inspection device 150 is capable of communicating with the printer engine 130 via a camera unit 135, and is also capable of communicating via a communication I / F 139.

[0023] 2 is an explanatory diagram of the inspection device 150. The inspection device 150 includes a CPU 151, a ROM 152, a RAM 153, a storage 154, a network I / F 155, a controller communication I / F 156, a camera I / F 157, and a printer engine I / F 158.

[0024] The CPU 151 controls the inspection device 150 by executing computer programs such as a startup program stored in the ROM 152 and a control program stored in the storage 154. The storage 154 is a large-capacity storage device that temporarily stores large amounts of data such as image processing programs and image data. For example, an HDD or SSD is used for the storage 154. The RAM 153 provides a working area for the CPU 151 when executing processing. The RAM 153 stores the image processing program of the storage 154, images of print data obtained from the host computer 101, images of sheets captured by the camera unit 135, working data for image calculations, and the like.

[0025] The network I / F 155 controls communication with the host computer 101 and the controller 110 via the communication line 105. The controller communication I / F 156 controls communication with the controller 110 via serial communication. The camera I / F 157 controls communication with the printer engine 130 via high-speed serial communication, and is capable of receiving image information representing an image captured by the camera unit 135. The printer engine I / F 158 controls communication with the printer engine 130 via serial communication, and is capable of receiving sensor information from the printer engine 130.

[0026] The inspection device 150 acquires the inspection item settings, the comparison source image, etc. from the host computer 101 via the communication line 105. The inspection device 150 acquires control information such as page information of the print job from the controller 110. Under the control of the printer engine 130, the inspection device 150 acquires image information generated by reading from the sheet after image formation by the camera unit 135. The inspection device 150 performs inspection (inspection) by comparing the comparison source image with the image information acquired from the camera unit 135 based on the inspection item settings and page information.

[0027] The controller 110 and camera unit 135 of the printing device 100 are connected to an inspection device 150. The inspection device 150 inspects the image printed on the sheet based on the image read by the camera unit 135. The inspection level of the inspection device 150 can be set from the host computer 101 or the like via the communication line 105.

[0028] 3 is a configuration diagram of the printer engine 130. The printer engine 130 is configured to include an image forming unit 200 that forms an image on a sheet, an image fixing unit 220, a paper reading unit 240, a camera unit 135, a stacker 260, and a finisher 280. The sheet is transported in this order, with the image forming unit 200 at the most upstream position, the image fixing unit 220, the paper reading unit 240, the camera unit 135, the stacker 260, and the finisher 280. The image forming unit 200 and the image fixing unit 220 make up an image forming section.

[0029] The image forming unit 200 includes a first paper feed deck 201, a second paper feed deck 202, image forming units 204Y, 204M, 204C, and 204K, an intermediate transfer belt 211, a secondary transfer inner roller 212, and a secondary transfer outer roller 213. The secondary transfer inner roller 212 and the secondary transfer outer roller 213 form a secondary transfer unit 214. The image forming units 204Y, 204M, 204C, and 204K develop visible toner images of yellow, magenta, cyan, and black. Each of the image forming units 204Y, 204M, 204C, and 204K includes a photosensitive drum 205, a charging roller 206, a laser scanner 207, a developing unit 208, and a toner hopper 209.

[0030] The first paper feed deck 201 and the second paper feed deck 202 can each store sheets on which an image is to be printed. The sheets stored in the first paper feed deck 201 and the second paper feed deck 202 do not necessarily have to be the same paper type or size. When a print job is executed, only the topmost sheet stored in the first paper feed deck 201 or the second paper feed deck 202 is separated and fed to a conveying path 203. The fed sheet is conveyed along the conveying path 203 to a secondary transfer unit 214.

[0031] The configurations of the image forming units 204Y, 204M, 204C, and 204K will be described below. Since the image forming units 204Y, 204M, 204C, and 204K have the same configuration, only the image forming unit 204Y will be described here. The photosensitive drum 205 is a photosensitive member having a photosensitive layer on its surface. The photosensitive drum 205 is driven to rotate around the drum axis. The charging roller 206 uniformly charges the surface of the rotating photosensitive drum 205. The laser scanner 207 exposes the charged surface of the photosensitive drum 205 to laser light according to raster image data, thereby forming an electrostatic latent image on the surface of the photosensitive drum 205. The developer 208 develops the electrostatic latent image into a visible toner image.

[0032] In this way, a yellow toner image is formed on the surface of the photosensitive drum 205 of the image creating unit 204Y. A magenta toner image is formed on the surface of the photosensitive drum 205 of the image creating unit 204M. A cyan toner image is formed on the surface of the photosensitive drum 205 of the image creating unit 204C. A black toner image is formed on the surface of the photosensitive drum 205 of the image creating unit 204K. The toner hopper 209 transports toner of the corresponding color from a toner bottle (not shown) and supplies a stable, predetermined amount of toner to the corresponding developing device 208.

[0033] Primary transfer rollers 210 are disposed at positions facing the photosensitive drums 205 of the image forming units 204Y, 204M, 204C, and 204K across the intermediate transfer belt 211. A primary transfer bias is applied to the primary transfer rollers 210, whereby toner images of each color are transferred from the photosensitive drums 205 onto the intermediate transfer belt 211 in a superimposed manner.

[0034] The intermediate transfer belt 211 rotates clockwise in the figure, and a four-color full-color image is formed by superimposing and transferring the toner images of each color from the photosensitive drums 205 of the image forming units 204Y, 204M, 204C, and 204K. The intermediate transfer belt 211 also rotates to transport the formed full-color image to the secondary transfer unit 214. The secondary transfer unit 214 transfers the toner images of each color carried by the intermediate transfer belt 211 all at once onto a sheet by a secondary transfer bias applied between the inner secondary transfer roller 212 and the outer secondary transfer roller 213. To transfer the toner images to predetermined positions on the sheet, the timing at which the sheet is transported to the secondary transfer unit 214 and the timing at which the toner images are transported to the secondary transfer unit 214 are adjusted. The sheet onto which the toner images have been transferred is transported to the image fixing unit 220.

[0035] A first optical sensor 215 and a second optical sensor 216 are disposed downstream of the image forming unit 204K and upstream of the secondary transfer unit 214 in the rotation direction of the intermediate transfer belt 211. The first optical sensor 215 irradiates light onto a patch pattern, which is a toner image formed on the intermediate transfer belt 211 by the image forming units 204Y, 204M, 204C, and 204K, and detects the amount of reflected light to detect the image density of the toner image. The second optical sensor 216 irradiates light onto a color shift detection pattern, which is a toner image of each color formed on the intermediate transfer belt 211 by the image forming units 204Y, 204M, 204C, and 204K, and detects the timing of changes in the amount of reflected light. The second optical sensor 216 can detect the amount of color shift of the toner images of each color, yellow, magenta, cyan, and black.

[0036] The image fixing unit 220 includes a fixing device 221, a paper discharge path 227, a reversing path 228, a reversing standby path 229, a paper re-feed path 231, a paper discharge flapper 226, and a reversing flapper 230. The fixing device 221 permanently fixes the toner image to the sheet by thermal fixing. The fixing device 221 includes a fixing belt unit 222, a pressure roller 223, a heater 224, and a refresh roller 225.

[0037] The fixing belt unit 222 is constructed by stretching a fixing belt, which is a metal belt with a silicone rubber elastic member laminated on its surface, over metal rollers. The fixing belt unit 222 is heated by a heater 224. The pressure roller 223 has the function of nipping and conveying a sheet between the fixing belt unit 222 and the pressure roller 223, and applying pressure. The toner on the sheet that is nipped and conveyed between the fixing belt unit 222 and the pressure roller 223 is melted and pressed, thereby fixing a toner image. This forms a full-color image on the sheet.

[0038] The refreshing roller 225 is normally spaced apart from the fixing belt unit 222, and is brought into contact with the fixing belt unit 222 at predetermined time intervals by a drive unit (not shown) and driven to rotate. As the refreshing roller 225 rotates in contact with the fixing belt unit 222, the surface of the fixing belt unit 222 is polished and smoothed. This allows the fixing belt unit 222 to maintain good fixing characteristics.

[0039] The sheet that has passed through the fixing device 221 is conveyed to a paper discharge path 227 by a paper discharge flapper 226 if single-sided printing or double-sided printing has completed image formation on both sides. The sheet conveyed to the paper discharge path 227 is conveyed to a paper reading unit 240.

[0040] When double-sided printing is performed and image formation is completed on only one side, the sheet that has passed through the fixing device 221 is conveyed to a reversing path 228 by a paper discharge flapper 226. The sheet conveyed to the reversing path 228 is conveyed to a reversing standby path 229, then conveyed in reverse, and conveyed to a re-feeding path 231 by a reversing flapper 230. This inverts the image-forming side of the sheet. The sheet is conveyed again via a sheet conveying path 203 to the secondary transfer unit 214. In the secondary transfer unit 214, a toner image is transferred to the inverted image-forming side of the sheet. This completes image formation on both sides of the sheet.

[0041] The paper reading unit 240 includes CIS (Contact Image Sensor) units 321 and 322 and a conveying path 243. The CIS units 321 and 322 are disposed opposite each other with the conveying path 243 in between. FIG. 4 is a configuration diagram of the CIS units 321 and 322. The CIS unit 321 is used to read an image on one side (referred to as the upper side or first side) of the sheet S conveyed on the conveying path 243. The CIS unit 322 is used to read an image on the other side (referred to as the lower side or second side) of the sheet S conveyed on the conveying path 243. In this embodiment, the CIS units 321 and 322 read an image formed on the sheet S at a resolution of, for example, 600 dpi.

[0042] The CIS unit 321 has a white LED (Light Emitting Diode) 350 serving as a light source, a reading sensor 351, and a white plate 352 serving as a reference member for shading. The CIS unit 322 has a white LED 353 serving as a light source, a reading sensor 354, and a white plate 355 serving as a reference member for shading. When an adjustment chart on which an adjustment image indicating image formation conditions or the like is formed is transported to the transport path 243, the CIS units 321 and 322 each perform a reading process for the adjustment image when the adjustment chart passes a predetermined reading position.

[0043] The adjustment image is read by the CPU 131 by illuminating the white LEDs 350 and 353. The light from the white LEDs 350 and 353 reflected by the adjustment image is received by the reading sensors 351 and 354. The reading sensors 351 and 354 photoelectrically convert the received reflected light to generate an electrical signal, which is then stored in the RAM 133 as sheet image information. In this manner, the adjustment image is read. The reading sensors may be optical sensors such as CCD image sensors.

[0044] The CPU 131 stabilizes the print density and print position accuracy by feeding back the image density of the adjustment image and the amount of color misregistration of each color to the image forming conditions and adjusting the image forming conditions based on the sheet image information stored in the RAM 133. In addition, the sheet image information acquired by the paper reading unit 240 is also sent to the inspection device 150.

[0045] The sheet that has passed through the paper reading unit 240 is conveyed to the camera unit 135. In the camera unit 135, a camera 251 and a camera 252 are arranged at positions facing each other across a conveying path 253. The camera 251 reads an image of the upper surface of the sheet. The camera 252 reads an image of the lower surface of the sheet. When the sheet conveyed on the conveying path 253 reaches the shooting positions of the cameras 251 and 252, the camera unit 135 reads images of both sides of the sheet using the cameras 251 and 252. The camera unit 135 transmits sheet image information, which is the reading result, to the inspection device 150. The sheet that has passed through the camera unit 135 is conveyed to the stacker 260.

[0046] The cameras 251 and 252 may be any cameras capable of optically reading images. The cameras 251 and 252 may be realized using, for example, a contact image sensor (CIS), a line scan camera, etc. Examples of line scan cameras include a charge coupled device (CCD) sensor and a complementary metal oxide semiconductor (CMOS) sensor.

[0047] The stacker 260 is a large-capacity stacker capable of stacking a large number of sheets. The stacker 260 includes a stack tray, which is configured as a tray for stacking sheets and is composed of a lift table 270 and an eject table 269. The stacker 260 also includes an escape tray 266, which is a discharge destination for sheets determined to be abnormal by inspection (defective sheets), and a conveying path 268 for conveying sheets to the finisher 280. To convey sheets to the stack tray, the stacker 260 includes conveying paths 261, 263, 267, flappers 264, 265, and a belt conveying unit 267. An inverting unit 262 is provided midway along the conveying path 261. Sheets conveyed from the camera unit 135 are conveyed to one of the discharge destinations based on the designation information of the print job or the determination result by the inspection device 150.

[0048] A sheet determined to be abnormal by the inspection device 150 is conveyed through conveyance paths 261 and 263 and discharged to an escape tray 266 by flappers 264 and 265. An adjustment chart, from which an adjustment image has been read by the paper reading unit 240, is also discharged to the escape tray 266 in the same manner.

[0049] For sheets determined to be normal by the inspection device 150 or sheets excluded from inspection due to the print job specifications, the discharge destination is determined based on the print job specifications. If the discharge destination is determined to be a stack tray based on the print job specifications, the sheets are loaded onto the lift table 270 via conveyance paths 261 and 263, a flapper 264, and a belt conveyance unit 267. If post-processing is required based on the print job specifications, the sheets are conveyed to the finisher 280.

[0050] The lift table 270 can move up and down and is positioned at the upper side when no sheets are loaded. As sheets are loaded, the lift table 270 lowers by the height (thickness) of the multiple sheets (sheet stack) loaded. This allows the top surface of the sheet stack loaded on the lift table 270 to be always controlled to a constant height.

[0051] When the loading of sheets onto the lift table 270 is completed or the lift table 270 is fully loaded, the lift table 270 descends to the position of the eject table 269. The lift table 270 and the eject table 269 are configured so that the bars supporting the sheet stack interlock with each other. Therefore, when the lift table 270 descends and reaches a position lower than the eject table 269, the sheet stack on the lift table 270 is transferred to the eject table 269. The eject table 269 is pulled out toward the front in the drawing with the transferred sheet stack loaded on it. The user can easily remove the sheet stack on the pulled-out eject table 269.

[0052] It should be noted that sheets loaded on the stack tray are first sent to the inverting unit 262. When sheets are loaded on the stack tray, they are flipped onto the lift table 270 and are therefore inverted upside down when loaded. To prevent this and to align the sheet orientation, the sheets are sent to the inverting unit 262 and their orientation is inverted. Sheets transported to the escape tray 266 or the finisher 280 are not inverted by the inverting unit 262.

[0053] The finisher 280 performs predetermined post-processing set by the user according to the print job on sheets obtained from the stacker 260. The finisher 280 is capable of post-processing such as stapling (one-point or two-point binding), punching (two-hole or three-hole), and saddle-stitch binding. The finisher 280 has three paper discharge units: two paper discharge trays 284 and 286 and a saddle-stitch binding tray 288. The finisher 280 has flappers 281 and 282, a saddle stitching unit 283, a staple binding unit 285, and a conveying unit 287.

[0054] When post-processing such as stapling is not performed, the sheets are discharged to a paper output tray 284 by flappers 281 and 282. When stapling is performed, the sheets are transported to a stapler unit 285 by flappers 281 and 282. The stapler unit 285 performs staple processing on the transported sheets. The stapled sheets are discharged to a paper output tray 286.

[0055] When saddle stitching is set as post-processing, the sheets are transported to the saddle stitching unit 283. The saddle stitching unit 283 staples the sheets in the center, then folds the sheets in half and saddle stitches them. When the saddle stitching is complete, the bound sheet bundle (saddle stitched bundle) is discharged to a saddle stitching tray 288 via a transport unit 287. The saddle stitching tray 288 is configured as a belt conveyor. The saddle stitched bundle loaded on the saddle stitching tray 288 is transported to the left side in the figure by the belt conveyor.

[0056] (Inspection method) The inspection device 150 inspects (inspects) the sheet image information acquired from the camera unit 135 according to preset inspection items. There are various inspection items, but here, as an example, a barcode readability inspection and a front / back comparison inspection will be described.

[0057] 5 is an explanatory diagram of the inspection of sheet image information. An upper surface read image 401 is a sheet image obtained by reading an image of the upper surface of a sheet, and is a read image by camera 251. A lower surface read image 402 is a sheet image obtained by reading an image of the lower surface of a sheet, and is a read image by camera 252. Inspection areas 410 and 421 to be inspected are provided in the upper surface read image 401, and an inspection area 422 to be inspected is provided in the lower surface read image 402.

[0058] The inspection device 150 first determines whether the barcode in the inspection area 410 is readable. If the barcode is readable, it is determined that the barcode was printed correctly. If the barcode is unreadable, it is determined that there is an abnormality in the barcode printing. Next, the inspection device 150 extracts the numerical values ​​in the inspection areas 421 and 422 as character data using character recognition such as OCR (Optical Character Recognition). Here, it is assumed that the print job is configured so that the same numerical values ​​are printed on both the front and back surfaces (top and bottom) of the sheet if printing is performed correctly. This determines whether printing is performed as intended on both surfaces of the sheet. If the numerical values ​​extracted from the inspection areas 421 and 422 are the same, it determines that the printing is normal. If they are different, it determines that the printing is abnormal. The inspection device 150 performs these inspections, and if any of the inspections determine that there is an abnormality in the printing, it determines the sheet as an "abnormal sheet." If neither inspection detects an abnormality, it determines the sheet as a "normal sheet."

[0059] The inspection device 150 is also capable of various other inspections such as print position inspection, sheet overlap inspection, sheet missing inspection, color misalignment inspection, color tint inspection, streak detection, dot detection, and full image comparison inspection of the read image and original data.

[0060] In this embodiment, the above-mentioned setting of the inspection area and inspection contents for the inspection device 150 can be performed from the host computer 101, the operation panel 120 of the printing device 100, or the like via the communication line 105. When a full image comparison inspection is performed, the inspection device 150 acquires a comparison source image from the host computer 101, or the like. Alternatively, an operation unit may be provided in the inspection device 150, and the inspection area and inspection contents may be set from this operation unit.

[0061] 6 is an example diagram of an inspection setting screen for setting the inspection area and inspection contents in the inspection device 150. The inspection setting screen is a screen for the user to specify inspection settings including the inspection area where inspection is to be performed by the inspection device 150 and the inspection level indicating the inspection accuracy. Here, an example will be described in which the inspection setting screen is displayed on a display provided in the host computer 101. For this purpose, the inspection setting is performed by the host computer 101. Note that when the inspection setting is performed by the printing device 100, the inspection setting screen is displayed on the display 120a of the operation panel 120.

[0062] The inspection setting screen displays an image 704 to be printed, inspection areas 705a and 705b, an inspection exclusion area 711, and the like in a display area 700. Buttons 701a, 701b, and 701c and pull-down menus 702a and 702b are also displayed on the inspection setting screen. The host computer 101 is provided with various input devices such as a keyboard, a touch panel, and a pointing device. By operating the buttons 701a, 701b, and 701c and the pull-down menus 702a and 702b using such input devices, the inspection areas 705a and 705b and the inspection exclusion area 711 are set.

[0063] Inspection area 705a is a standard inspection area that is set by operating button 701a. For example, a user can set inspection area 705a by operating button 701a and determining a range within image 704 with a pointing device or the like. In the standard inspection area, for example, standard inspections are performed. The standard inspections include, for example, misalignment detection, color detection, and streak detection. The standard inspections may be changed depending on the image printed on the printed material. For example, if the image is text, color detection may be excluded from the standard inspections.

[0064] The pull-down menu 702a is operated to set the inspection level (inspection accuracy) to be applied to the inspection area 705a. In this example, "inspection level 1" has the lowest inspection accuracy, and the inspection accuracy increases as the inspection level number increases. The maximum inspection level is, for example, "10" (inspection level 10). The pull-down menu may also be called a drop-down list.

[0065] Inspection area 705b is a priority inspection area that is set by operating button 701b. For example, the user can set inspection area 705b by operating button 701b and determining the range within image 704 with a pointing device or the like. In the priority inspection area, for example, a high-precision inspection is performed, and more inspection content is included than in the standard inspection area. In the example of FIG. 6, a high-precision inspection with more inspection content than in the standard inspection area is performed on shapes such as circles and crosses within inspection area 705b. Pull-down menu 702b is operated to set the inspection level (inspection precision) to be applied to inspection area 705b.

[0066] The inspection exclusion area 711 is an area in which inspection is not performed, which is set by operating the button 701c. For example, the user can set the inspection exclusion area 711 by operating the button 701c and determining the range within the image 704 with a pointing device or the like. Here, it is not necessary to inspect the cylinders and triangles within the inspection exclusion area 711. Therefore, the area including these shapes is set as the inspection exclusion area 711.

[0067] In this way, the inspection content and inspection level can be set for each area of ​​the image 704 to be printed. This allows the user to set appropriate inspection standards for each area. As a result, printouts of acceptable quality are judged to be normal, reducing unnecessary reprints and improving productivity. It also reduces unnecessary sheet disposal.

[0068] (Automatic adjustment) The automatic adjustment operations performed by the printing device 100 of this embodiment will now be described. As the printing device 100 (printer engine 130) continues to form images, there is a possibility that factors such as deterioration of components over time, fluctuations in temperature and humidity, deformation of members, and adhesion of foreign matter to the cameras 251 and 252 and CIS units 321 and 322 may occur. The printing device 100 performs automatic adjustment operations to continue to maintain a certain level of image quality even when affected by these factors. Examples of automatic adjustment operations include color misregistration correction, toner gradation density correction, fuser roller surface refresh control, shading correction for the CIS units 321 and 322, and dust correction for the CIS units 321 and 322. These operations will now be described.

[0069] Color misregistration correction will now be described. Color misregistration correction is a control that corrects the color misregistration of the yellow, magenta, cyan, and black toner images when the image forming units 204Y, 204M, 204C, and 204K and the laser scanner 207 form the respective color toner images. The amount of color misregistration varies due to factors such as temperature changes in the photosensitive drums 205 of the image forming units 204Y, 204M, 204C, and 204K and the laser scanner 207. For this reason, it is necessary to detect the current amount of color misregistration during execution of a print job, calculate an appropriate amount of color misregistration correction, and correct image formation conditions such as the start position of laser light irradiation by the laser scanner 207 (image writing timing).

[0070] 7 is an explanatory diagram of an adjustment image for color misregistration correction. The adjustment image 1011 is a pattern image formed of toner images of each color, yellow, magenta, cyan, and black, and is formed on the intermediate transfer belt 211. The second optical sensor 216 has reflected light intensity sensors 1001, 1002, and 1003 arranged in a direction intersecting the rotation direction of the intermediate transfer belt 211. The adjustment image 1011 is arranged in three rows in a direction intersecting the rotation direction of the intermediate transfer belt 211, depending on the reading positions of the reflected light intensity sensors 1001, 1002, and 1003. The amount of color misregistration of yellow, magenta, cyan, and black is detected based on the difference in detection timing of the pattern images of each color by the reflected light intensity sensors 1001, 1002, and 1003.

[0071] The amount of color misregistration includes misalignment in the main scanning direction when the laser scanner 207 scans the photosensitive drum 205, misalignment in the sub-scanning direction, which is the rotation direction of the photosensitive drum 205 and the intermediate transfer belt 211, and so on. It is possible to suppress color misregistration by adjusting the writing timing of the laser scanner 207 based on the amount of color misregistration of yellow, magenta, cyan, and black detected from the adjustment image for color misregistration correction.

[0072] The color misregistration correction operation may be performed between normal image formation of each page, but to perform correction with higher precision, the image formation interval between each page may be intentionally extended and an operation to detect the amount of color misregistration may be performed by forming adjustment images for two or more revolutions of the photosensitive drum 205. In this embodiment, in the initial state, the image formation interval between each page is intentionally extended and color misregistration correction is performed once every 100 sheets of image formation.

[0073] The toner gradation density correction will now be described. The toner gradation density correction is a control for obtaining stability in the halftone density reproduced by the dither pattern when the image forming units 204Y, 204M, 204C, and 204K generate visible toner images. The halftone image information included in the print job is converted into a dither pattern by the controller 110 and used for exposure of the laser scanner 207. At this time, the stability of the dots forming the dither pattern changes depending on the state of the toner in the developer 208, and the halftone image density may change over time.

[0074] 8 is an explanatory diagram of an adjustment image for gradation density correction. The adjustment image 1111 is a halftone patch pattern image formed with toner images of each color of yellow, magenta, cyan, and black, and is formed on the intermediate transfer belt 211. The first optical sensor 215 has reflected light intensity sensors 1101, 1102, and 1103 arranged in a direction intersecting the rotation direction of the intermediate transfer belt 211. The adjustment image 1111 is arranged in three rows in a direction intersecting the rotation direction of the intermediate transfer belt 211, according to the reading positions of the reflected light intensity sensors 1101, 1102, and 1103, respectively.

[0075] The reflected light intensity sensors 1101, 1102, and 1103 receive light reflected from the halftone patch pattern image and read the amount of reflected light. The reflected light intensity sensors 1101, 1102, and 1103 irradiate the toner image (adjustment image 1111) formed on the intermediate transfer belt 211 with light and receive the specularly reflected light and diffusely reflected light. The reflected light intensity sensors 1101, 1102, and 1103 AD convert electrical signals corresponding to the amount of specularly reflected light and diffusely reflected light. The halftone density of each color can be obtained by applying a calculation formula appropriate for each color to each AD conversion value obtained by AD conversion.

[0076] A lookup table is generated to inversely correct the detected halftone densities of yellow, magenta, cyan, and black to the intended halftone densities, thereby maintaining the intended characteristics of the halftone densities.

[0077] The toner gradation density correction operation may be performed between normal image formation of each page. To perform correction with higher precision, the image formation interval for each page may be intentionally extended, and multiple halftone patch pattern images may be formed, thereby performing highly accurate toner gradation density correction operation from low density range to high density range. In this embodiment, in the initial state, the image formation interval for each page is intentionally extended and toner gradation density correction is performed once every 200 sheets of image formation.

[0078] The following describes the fixing roller surface refresh control. As described above, the surface layer of the fixing belt unit 222 is made of an elastic material to ensure good toner image fixation. Therefore, when sheets of the same paper width are continuously conveyed, a step may occur on the surface layer of the fixing belt unit 222 at the cross section of the sheet, i.e., at the edge of the paper. If a sheet wider than the step width arrives in this state, this step will cause a difference in thermal fixation. This step may appear as a glossy streak. In particular, if the step on the surface layer of the fixing belt unit 222 overlaps with a solid portion of a wide sheet, it will result in a noticeable glossy streak, leading to a decrease in image quality.

[0079] The refreshing roller 225 is normally spaced apart from the fixing belt unit 222, but is brought into contact with the fixing belt unit 222 at predetermined time intervals by a drive unit (not shown) and driven to rotate. By bringing the refreshing roller 225 into contact with the fixing belt unit 222 and driving it to rotate, unevenness that occurs on the fixing belt unit 222 is smoothed out.

[0080] The operation of smoothing out unevenness that occurs on the fixing belt unit 222 using the refresh roller 225 needs to be performed at regular intervals so that it is ready for the arrival of pages, including wide-width sheets. However, during this operation, jitter occurs in the rotation of the fixing belt, making it impossible to perform normal fixing operations on sheets. For this reason, the image formation interval for each page is intentionally widened to temporarily suspend the arrival of normal sheets, and then the fixing belt surface is smoothed. In this embodiment, the fixing roller surface refresh control is initially set to be performed every time 300 sheets have been fixed.

[0081] The shading correction of the CIS units 321 and 322 will now be described. As shown in Fig. 4, the CIS unit 321 turns on a white LED 350 controlled by a CPU (not shown) to irradiate the front surface of the sheet S with light. The light reflected by the sheet S is received by a reading sensor 351. Based on the reception result of the reflected light by the reading sensor 351, the image density on the front surface of the sheet S is detected.

[0082] At this time, light is irradiated linearly in a direction intersecting the conveyance direction of the sheet S. The reading sensor 351 has a plurality of photoelectric conversion elements arranged in the same direction as the direction intersecting the conveyance direction of the sheet S (the direction of the linear light). Therefore, the main scanning direction of the CIS unit 321 is the direction intersecting the conveyance direction of the sheet S. The sub-scanning direction is the conveyance direction of the sheet S. The same applies to the CIS unit 322.

[0083] The light emitted from the white LED 350 has uneven light intensity in the main scanning direction, and the reading sensor 351 also has uneven sensitivity in the main scanning direction. Such uneven light intensity and uneven sensitivity affect the detection characteristics of the image density in the main scanning direction of the CIS unit 321. To detect image density stably, correction according to this detection characteristic is required.

[0084] The unevenness in the amount of light and the unevenness in sensitivity vary depending on the lighting time and temperature changes of the white LED 350, and the driving time and temperature changes of the reading sensor 351. For this reason, it is necessary to move the white plate 352 to the reading position of the white LED 350 using a white plate drive motor (not shown), and then read it with the reading sensor 351 to obtain the detection characteristics in the reference state and perform shading correction.

[0085] During shading correction, the white LED 350 and the reading sensor 351 are blocked from the side of the sheet S by the movement of the white plate 352, and therefore it is not possible to detect the image density of the sheet S. For this reason, shading correction must be performed after intentionally extending the imaging interval between each page and temporarily suspending the arrival of the normal sheet S.

[0086] Similarly, shading correction must be performed on the CIS unit 322. In this embodiment, in the initial state, the shading correction of the CIS units 321 and 322 is set to be performed every time 500 sheets S are printed.

[0087] The print position adjustment control will now be described. Fig. 9 is an example diagram of a print position adjustment chart used for print position adjustment. An upper surface print position adjustment image 800 is formed on the upper surface of the sheet. A lower surface print position adjustment image 801 is formed on the lower surface of the sheet. The print position adjustment image 800 and the print position adjustment image 801 are similar images. The print position adjustment images 800 and 801 each include a mark 820 printed at a specific position.

[0088] The mark 820 on the print position adjustment image 800 for the upper surface is read by the camera 251. The mark 820 on the print position adjustment image 801 for the lower surface is read by the camera 252. The mark 820 is usually formed with toner of a color that has a large difference in reflectance with respect to the sheet. In this embodiment, the mark 820 is formed with black toner.

[0089] The marks 820 are printed in a total of eight locations, one at each of the four corners of the top and bottom surfaces of the print position adjustment images 800 and 801. Each mark 820 is positioned so that, if the print position is ideal, it will be printed at a fixed distance from the edge of the sheet. By measuring the relative positions of each mark 820 on the print position adjustment images 800 and 801, the amount of deviation in the print position can be obtained.

[0090] In this embodiment, the portions represented by (A) to (R) in Figure 9 are the measurement values ​​for adjusting the print position. (A) is the length of the print position adjustment chart in the main scanning direction. (B) is the length of the print position adjustment chart in the sub-scanning direction. (C) to (R) are the distances from the marks 820 to the nearest sheet edge. Ideally, each mark 820 is printed at a predetermined distance, for example 1 cm here, from the corresponding sheet edge.

[0091] A method for calculating the amount of print position deviation will now be described with reference to Fig. 10, which is an explanatory diagram of a method for calculating the amount of print position deviation.

[0092] Fig. 10(a) is an example diagram of the results of reading the print position adjustment image 800 for the upper surface in Fig. 9 by the camera 251. Here, the distances (C) to (J) between the mark 820 and the sheet edge are expressed as (x11, y11), (x12, y12), (x13, y13), and (x14, y14) in a coordinate system with a predetermined position as the reference position. Furthermore, each coordinate is connected by a straight line.

[0093] First, a right-angle correction is performed to make the line connecting (x11, y11) and (x12, y12) at the leading edge of the image perpendicular to the line connecting (x11, y11) and (x13, y13). As shown in Figure 10(b), the right-angle correction is performed by determining and correcting the sub-scanning writing position of the image at each position in the main scanning direction, using position (x101, y101), which is half the length of the line connecting (x11, y11) and (x12, y12), as the reference point. As a result, (x11, y11) becomes (x21, y21), (x12, y12) becomes (x22, y22), (x13, y13) becomes (x23, y23), and (x14, y14) becomes (x24, y24).

[0094] Next, keystone correction is performed to make the line connecting (x23, y23) and (x24, y24) at the rear end of the image perpendicular to the line connecting (x21, y21) and (x23, y23). As shown in Figure 10(c), keystone correction is performed using (x102, y102), a position halfway along the line connecting (x23, y23) and (x24, y24), as the base point. Keystone correction is performed by calculating and correcting the magnification in the sub-scanning direction at each position in the main scanning direction so that (x23, y23) becomes (x33, y33) and (x24, y24) becomes (x34, y34).

[0095] Next, as shown in Figure 10(d), the length of the image in the main scanning direction and sub-scanning direction is set to the ideal length (paper length - 2 [cm] in both the main scanning direction and sub-scanning direction). To do this, the magnifications in the main scanning direction and sub-scanning direction are calculated, and magnification correction is performed using the center of the image as the reference. Magnification correction is performed by correcting (x21, y21) to (x41, y41), (x22, y22) to (x42, y42), (x33, y33) to (x43, y43), and (x34, y34) to (x44, y44).

[0096] 10(e), the line connecting (x103, y103) and (x104, y104) on the sheet is made parallel to the line connecting (x41, y41) and (x43, y43) on the image. To achieve this, the image is rotated by θ2 with (x41, y41) as the reference point, and the skew is corrected so that (x42, y42) becomes (x52, y52), (x43, y43) becomes (x53, y53), and (x44, y44) becomes (x54, y54).

[0097] Next, as shown in Figure 10(f), the write start positions in the main scanning direction and sub-scanning direction are calculated and corrected so that the center of the sheet and the center of the image are aligned. By performing this calculation and correction, the image is corrected as shown in Figure 10(g). The bottom surface is also corrected in the same way. In this embodiment, the initial setting is to adjust the print position every time 400 sheets S are printed.

[0098] (Printing and inspection processing) FIG. 11 is a sequence diagram showing the exchange of information during the printing process and the inspection process of this embodiment.

[0099] When setting the inspection level, the host computer 101 notifies the inspection device 150 of the inspection level value and the comparison source image to be used in the inspection (S301). The inspection device 150 saves the inspection level value and comparison source image acquired from the host computer 101, and notifies the inspection level value to the printer engine 130 (S302). The printer engine 130 sets the adjustment frequency based on the acquired inspection level value (S303).

[0100] When printing, controller 110 transmits a print instruction and print data (image data) to printer engine 130. Printer engine 130 executes print processing based on the print instruction and print data (S304). Printer engine 130 counts the number of printed sheets during printing, and determines whether to perform an adjustment operation based on the count result and an adjustment frequency preset in printer engine 130 (S306). If printer engine 130 determines that an adjustment operation should be performed, it performs the adjustment operation (S307).

[0101] While the printing device 100 is performing the printing process, the inspection device 150 inspects the image transmitted from the printer engine 130 each time a sheet is conveyed (S305). The image transmitted here is image information representing the image read by the camera unit 135 and the paper reading unit 240.

[0102] If the inspection device 150 detects an abnormality in the product during printing (S308), the inspection device 150 notifies the printer engine 130 of the inspection result at the time of the abnormality. The printer engine 130 performs adjustments to address the abnormality (S309). The printing device 100 performs the above processes of S304 to S309 until printing is completed.

[0103] (Printer engine and image quality) The printer engine 130 and image quality will now be described. FIG. 12 is an explanatory diagram of the image quality characteristics of output images formed by two printer engines. For example, printer engine A has a color quality of "medium." Printer engine B has a color quality of "high." With regard to image misregistration, printer engine A is superior to printer engine B in quality and is therefore "high."

[0104] That is, in a configuration in which printer engine A and inspection device 150 are connected, if a strict inspection level is set for color, it is unlikely that images that satisfy the color inspection level can be continuously output. However, in this configuration, if a strict inspection level is set for the image misalignment item, it is highly likely that images that satisfy the image misalignment inspection level can be continuously output. The opposite is true in a configuration in which printer engine B and inspection device 150 are connected.

[0105] As such, even if the same inspection level is set for the same inspection item, different printer engines will produce different inspection results due to differences in their performance. Therefore, when a user sets a high inspection level to perform a high-precision inspection, some printer engines may not be able to output images with the image quality corresponding to the inspection level, resulting in an increase in deliverables that are determined to have an abnormality. Therefore, in this embodiment, adjustments are performed at a frequency according to the inspection level, thereby preventing downtime that would otherwise occur due to adjustment operations after the printer engine is stopped due to a determination of an abnormality.

[0106] (Image quality and adjustment frequency) The relationship between the image quality that satisfies the inspection level and the frequency of adjustment will be explained using a diagram showing the relationship between the number of prints (number of deliverables) that can satisfy the inspection level and the color quality of the image.

[0107] FIG. 13 is an explanatory diagram of the relationship between the number of printed pages and the color quality of an image after toner gradation density correction is performed by the printer engine 130. As shown in FIG. 13, even with a printer engine with a color quality of "medium," the output can meet the highest inspection level of "10" for a while (approximately 70 printed pages) after toner gradation density correction, which corrects the color. However, as the number of printed pages increases, the stability of the dots that form the dither pattern changes depending on the condition of the toner in the developer, causing the density of the halftone image to change over time. As a result, the color quality may not be met before the next toner gradation density correction timing, increasing the likelihood that the image will be determined to be abnormal.

[0108] Therefore, if a user expects higher quality in terms of color and sets the inspection level more stringently, for example, to the maximum of "10," and performs inspection using the inspection device 150, the color quality may be satisfied immediately after adjustment, but as the number of printed sheets increases, the possibility of determining an abnormal image increases. Therefore, in this embodiment, toner gradation density correction is performed at a frequency according to the inspection level.

[0109] The frequency of toner gradation density correction according to the inspection level will now be described. FIG. 14 is an explanatory diagram of the frequency of toner gradation density correction according to the inspection level. Here, the standard setting value for the color inspection level is "6," and the corresponding frequency of toner gradation density correction is once every 200 printed pages. If the user sets the color inspection level to "10," toner gradation density correction will be performed every 40 printed pages. In other words, the higher the inspection level, the higher the frequency of the correction operation (adjustment operation). Here, the frequency of toner gradation density correction has been described as an example, but the same applies to other correction operations (adjustment operations). The adjustment frequency corresponding to the inspection level is not limited to a unique value and may vary depending on the performance of the printer engine and the type of adjustment.

[0110] The printer engine 130 stores, for example, in RAM 133, a table that is information showing the relationship between the inspection level and the frequency of toner gradation density correction, as shown in FIG. 14. This table is referenced by the CPU 131 when setting the adjustment frequency threshold, which will be described later. This table may also be displayed when the user sets the inspection level. For example, by displaying this table at the same time as the inspection setting screen of FIG. 6 is displayed, the user is notified of the relationship between the inspection level and the adjustment frequency. This allows the user to easily set the optimal inspection level. This table may also be displayed at the same time as the pull-down menus 702a and 702b are operated from the inspection setting screen.

[0111] When the inspection level is set in the host computer 101, this table is displayed on a display provided in the host computer 101. When the inspection level is set on the operation panel 120, this table is displayed on the display 120a of the operation panel 120. When the inspection device 150 is provided with a user interface for setting the inspection level, this table is displayed on the user interface.

[0112] Fig. 15 is a flowchart showing the process of determining the threshold value of the adjustment frequency according to the inspection level. This process is a detailed explanation of the process of S303 in Fig. 11. Here, the case where the adjustment frequency corresponding to the inspection level is that of Fig. 14 will be explained.

[0113] The CPU 131 of the printer engine 130 acquires an inspection level value indicating the inspection level from the inspection device 150 (S501). The CPU 131 sets an adjustment frequency threshold value according to the acquired inspection level value. When the number of printed sheets reaches the adjustment frequency threshold value, adjustment is performed. As described above, the CPU 131 determines the adjustment frequency threshold value by referring to the table indicating the toner gradation density correction frequency stored in the RAM 133.

[0114] If the inspection level is "10" (S502: Y), the CPU 131 selects 40 sheets as the adjustment frequency threshold (S503). If the inspection level is "9" (S502: N, S504: Y), the CPU 131 selects 80 sheets as the adjustment frequency threshold (S505). If the inspection level is "8" (S502: N, S504: N, S506: Y), the CPU 131 selects 120 sheets as the adjustment frequency threshold (S507). If the inspection level is "7" (S502: N, S504: N, S506: N, S508: Y), the CPU 131 selects 160 sheets as the adjustment frequency threshold (S509). If the inspection level does not fall under "10 to 7" (S502: N, S504: N, S506: N, S508: N), the CPU 131 selects 200 sheets as the adjustment frequency threshold (S510).

[0115] 16 is a flowchart showing the image forming process including the adjusting operation execution determination process, which is a detailed description of S304, S306, and S307 in FIG.

[0116] The CPU 131 of the printer engine 130 waits for a print job to be received from the controller 110 (S601: N). If a print job is received (S601: Y), the CPU 131 executes an image forming operation for one sheet (S602). The CPU 131 increments a passed paper number counter (S603). The passed paper number counter counts the number of printed sheets since the previous adjustment execution.

[0117] The CPU 131 compares the value of the passed paper number counter with the adjustment frequency threshold set in the process of S303 in Fig. 10 (process of Fig. 15) (S604). If the value of the passed paper number counter exceeds the adjustment frequency threshold (S604: Y), the CPU 131 stops the image forming operation and performs an adjustment operation (S605, S606). The CPU 131 clears the passed paper number counter (S607).

[0118] After the passed paper count counter is cleared, or if the value of the passed paper count counter does not exceed the adjustment frequency threshold (S604: N), CPU 131 determines whether the print job has ended (S608). If the print job has not ended (S608: N), CPU 131 repeats the processing from S602 onwards. If the print job has ended (S608: Y), CPU 313 ends the image forming processing.

[0119] As described above, the image forming system 1 of this embodiment performs image quality adjustment processing at time intervals according to the inspection level. That is, the frequency of the adjustment processing (adjustment frequency) is determined based on the inspection level. Therefore, even when a high inspection level is set, the adjustment processing is performed at an appropriate frequency, and a deliverable product with image quality that satisfies the inspection level can be obtained. This makes it possible to suppress downtime caused by repeated adjustment operations. It also makes it possible to suppress an increase in the number of sheets determined to be abnormal. In other words, even when an inspection level stricter than the image quality that the image forming system 1 can output is set, it is possible to generate a deliverable product with image quality that satisfies the inspection level by appropriately setting the frequency of the adjustment operation.

[0120] (Variation 1) In the above embodiment, the printing device 100 counts the number of sheets printed by the printer engine 130 and determines whether or not to perform an adjustment operation based on the counted number of sheets so that the adjustment frequency corresponds to the inspection level. However, it is not necessarily the printer engine 130 that counts the number of sheets and determines whether or not to perform an adjustment operation. Here, a configuration will be described in which the inspection device 150 counts the number of sheets and determines whether or not to perform an adjustment operation.

[0121] FIG. 17 is a sequence diagram showing the exchange of information during the printing process and the inspection process in this case.

[0122] When setting the inspection level, the host computer 101 notifies the inspection device 150 of the inspection level value and the comparison source image to be used in the inspection (S401). The inspection device 150 saves the inspection level value and comparison source image acquired from the host computer 101, and notifies the printer engine 130 of the inspection level value (S402). The printer engine 130 notifies the inspection device 150 of adjustment frequency information indicating the adjustment frequency based on the acquired inspection level value (S403). The adjustment frequency is set as shown in FIG.

[0123] When printing, the controller 110 transmits a print instruction and print data (image data) to the printer engine 130. The printer engine 130 executes print processing based on the print instruction and print data (S404).

[0124] The inspection device 150 counts the number of printed sheets based on the images sent from the printer engine 130, i.e., the image information of the images read by the camera unit 135 and the paper reading unit 240. The inspection device 150 compares the counted number of printed sheets with the adjustment frequency information acquired in the process of S403 (S405). When the number of printed sheets reaches the adjustment frequency, the inspection device 150 instructs the printer engine 130 to perform an adjustment operation (S406). The processes of S405 and S406 determine whether or not to perform the adjustment operation. Details of the adjustment operation execution determination process will be described later.

[0125] When the printer engine 130 receives the instruction to perform the adjustment operation, it interrupts the printing operation and performs the adjustment operation (S407). When the adjustment operation is completed, the printer engine 130 resumes the printing operation. When the inspection device 150 detects an abnormality in the deliverable, it notifies the printer engine 130 of the inspection result at the time of the abnormality (S408). The printer engine 130 executes adjustment processing to address the abnormality (S409).

[0126] 18 is a flowchart showing the adjustment operation execution determination process by the inspection device 150. This process is a detailed description of S405 and S406 in FIG.

[0127] The CPU 151 of the inspection device 150 determines whether to perform an inspection based on whether the print job is set to include an inspection (S701). If an inspection is not to be performed (S701: N), the CPU 151 repeats the process of S701 until the print job is set to include an inspection. If an inspection is to be performed (S701: Y), the CPU 151 acquires the adjustment frequency information notified from the controller 110 in S403 of FIG. 17 (S702).

[0128] The CPU 151 determines whether or not paper has passed (S703). Whether or not paper has passed is determined, for example, by whether or not image information of an image read by the camera unit 135 and the paper reading unit 240, obtained from the printer engine 130, is acquired. If no paper has passed (S703: N), the CPU 151 waits until paper has passed. If paper has passed (S703: Y), the CPU 151 inspects the target sheet (S704). The CPU 151 determines whether or not there is an abnormality based on the inspection result (S705). If there is an abnormality (S705: Y), the CPU 151 notifies the printer engine 130 of the inspection result indicating the occurrence of the abnormality (S706).

[0129] If no abnormality is found (S705: N), CPU 151 increments the number of sheets of paper passed counter (S707). The value of the number of sheets of paper passed counter indicates the number of sheets of paper passed since the previous adjustment was performed. CPU 151 compares the value of the number of sheets of paper passed counter with the adjustment frequency threshold set in the process of S403 in FIG. 17 (S708). If the value of the number of sheets of paper passed counter is greater than the adjustment frequency threshold (S708: Y), CPU 151 notifies printer engine 130 of a request to perform adjustment (S709). CPU 151 clears the number of sheets of paper passed counter (S710).

[0130] If the value of the passed paper number counter is equal to or less than the adjustment frequency threshold (S708: N), or after the processes of S706 and S710, the CPU 151 determines whether or not to end the inspection (S711). If not to end (S711: N), the CPU 151 repeats the processes from S703 onwards. If to end (S711: Y), the CPU 151 ends the adjustment operation execution determination process of the inspection device 150.

[0131] As described above, the inspection device 150 can also count the number of sheets and determine whether or not an adjustment operation should be performed.

[0132] (Variation 2) As described above, the inspection level is set using the inspection setting screen exemplified in FIG. 6. When setting the inspection level, the user can set an appropriate inspection level by knowing the adjustment frequency for each inspection level. FIG. 19 is an example of a message displayed in such a case. In this example, when the inspection level is 7 to 10, the adjustment frequency is 50 sheets or less, and when the inspection level is 5 to 7, the adjustment frequency is 100 sheets or less. The user can set the inspection level by referring to this message. The recommended inspection level may also be clearly indicated in the message.

[0133] The message in FIG. 19 is displayed, for example, when the user sets the inspection level. For example, by displaying the message when the inspection setting screen in FIG. 6 is displayed, the user can be notified of the relationship between the inspection level and the adjustment frequency. This allows the user to confirm the relationship between the inspection level and the adjustment frequency. This message may also be displayed when the pull-down menus 702a and 702b are operated from the inspection setting screen. Note that when the inspection level is set on the host computer 101, this message is displayed on a display provided on the host computer 101. When the inspection level is set on the operation panel 120, this message is displayed on the display 120a of the operation panel 120. If the inspection device 150 is provided with a user interface for setting the inspection level, this message is displayed on the user interface. Displaying such a message allows the user to set the inspection level according to the adjustment frequency.

[0134] (Variation 3) If the adjustment frequency is set in advance, restrictions will be placed on the setting of the inspection level. In this case, the inspection level must be set to satisfy the conditions in Fig. 14. In order for the user to set the adjustment frequency corresponding to the inspection level they wish to set, messages such as those shown in Figs. 20 and 21 are displayed.

[0135] The message in Fig. 20 is displayed, for example, when the adjustment frequency is set to every 200 sheets and one of the inspection levels 5 to 7 is selected. When one of the inspection levels 5 to 7 is selected, a notification is output urging the user to change the adjustment frequency to 100 sheets or less to satisfy the condition in Fig. 14.

[0136] The message in Fig. 21 is displayed, for example, when the adjustment frequency is set to every 200 sheets and one of the inspection levels 7 to 10 is selected. When one of the inspection levels 7 to 10 is selected, a notification is output urging the user to change the adjustment frequency to 50 sheets or less to satisfy the conditions in Fig. 14.

[0137] 20 and 21 are displayed when the user sets an inspection level from the inspection setting screen and the set level does not correspond to the preset adjustment frequency. When the inspection level is set on the host computer 101, this message is displayed on a display provided on the host computer 101. When the inspection level is set on the operation panel 120, this message is displayed on the display 120a of the operation panel 120. If the inspection device 150 is provided with a user interface for setting the inspection level, this message is displayed on the user interface. By displaying such a message, the user can set the adjustment frequency according to the inspection level.

[0138] (Variation 4) After a low inspection level is set and image formation is performed for a number of sheets less than the adjustment frequency, a high inspection level may be set before the start of printing for the next print job. In this case, changing the inspection level to a high level may satisfy the adjustment frequency condition.

[0139] For example, after images have been formed on 100 sheets at inspection level "3," the inspection level is set to "10" before printing for the next print job. When the inspection level is "10," the adjustment frequency is 40 sheets according to FIG. 14. This is less than the current number of printed sheets. In this case, since it is determined that the number of printed sheets exceeds the adjustment frequency threshold, an adjustment operation is performed and the number of sheets passed counter is cleared.

[0140] Furthermore, the image forming system 1 may perform an adjustment operation due to a restart caused by a power operation, etc. In this case, if it is determined whether or not to perform an adjustment operation based on the number of printed sheets before the restart, an adjustment operation that does not actually need to be performed may be performed. For this reason, if the image forming system 1 performs an adjustment operation when it is restarted, the passed paper count counter is cleared.

[0141] (Variation 5) The inspection level is set on the inspection setting screen in Fig. 6 as described above. On the inspection setting screen, the inspection level can be set for each area. Therefore, for example, different inspection levels may be set for the inspection area 705a and the inspection area 705b. In this case, the adjustment operation is performed at an adjustment frequency corresponding to the highest inspection level.

Claims

1. a printing means for printing an image on a sheet; an inspection means for inspecting an image formed on a sheet based on an inspection level set from among a plurality of inspection levels; an adjusting means for adjusting the image forming conditions of the printing means; a control means for causing the adjustment means to adjust the image forming conditions when an image is formed on a first number of sheets by the printing means when a first inspection level is set, and for causing the adjustment means to adjust the image forming conditions when an image is formed on a second number of sheets by the printing means when a second inspection level is set, when the inspection level is changed to the second inspection level before images are formed on the first number of sheets at the first inspection level, if the number of sheets on which images are formed at the first inspection level is equal to or greater than the second number, the control means causes the adjustment means to perform the adjustment; the second inspection level is higher than the first inspection level, and the second number of sheets is smaller than the first number of sheets. Imaging system.

2. the control means determines the first number of sheets as the interval for performing the adjustment when the first inspection level is set, and determines the second number of sheets as the interval for performing the adjustment when the second inspection level is set. The image forming system according to claim 1 .

3. further comprising an input means for setting the inspection level; The inspection means sets the inspection level by the input means, and notifies the control means of the set inspection level; The control means determines the number of sheets indicating the interval for performing the adjustment in accordance with the inspection level notified from the inspection means.

3. The image forming system according to claim 2.

4. The inspection device further includes a display means for displaying an inspection setting screen for setting the inspection level, the input means inputs information about the inspection level to be set on the inspection setting screen, 4. The image forming system according to claim 3.

5. the display means displays information indicating a relationship between the inspection level and the number of sheets indicating an interval at which the adjustment is performed when the inspection level is set on the inspection setting screen; the input means is configured to input an instruction of an inspection level to be set in accordance with the display by a user.

5. The image forming system according to claim 4.

6. The present invention is characterized in that the present invention further comprises an output means for outputting a notice prompting a change of the interval when the control means determines the number of sheets indicating the interval for performing the adjustment and the inspection level set by the input means does not correspond to the interval.

4. The image forming system according to claim 3.

7. a printing means for printing an image on a sheet; an inspection means for inspecting an image formed on a sheet based on an inspection level set from among a plurality of inspection levels; an adjusting means for adjusting the image forming conditions of the printing means; a control means for causing the adjustment means to adjust the image forming conditions when an image is formed on a first number of sheets by the printing means when a first inspection level is set, and for causing the adjustment means to adjust the image forming conditions when an image is formed on a second number of sheets by the printing means when a second inspection level is set; a counter that counts the number of sheets on which the printing means has formed an image, the control means clears the number of sheets counted by the counter when the adjustment means performs the adjustment before images are formed on the first number of sheets at the first inspection level, and clears the number of sheets counted by the counter when the adjustment means performs the adjustment before images are formed on the second number of sheets at the second inspection level; the second inspection level is higher than the first inspection level, and the second number of sheets is smaller than the first number of sheets. Imaging system.

8. a printing means for printing an image on a sheet; an inspection means for inspecting an image formed on a sheet based on an inspection level set from among a plurality of inspection levels; an adjusting means for adjusting the image forming conditions of the printing means; a control means for causing the adjustment means to adjust the image forming conditions when an image is formed on a first number of sheets by the printing means when a first inspection level is set, and for causing the adjustment means to adjust the image forming conditions when an image is formed on a second number of sheets by the printing means when a second inspection level is set; a display means for displaying an inspection setting screen for setting the inspection level; an input means for inputting information on the examination level set on the examination setting screen, the inspection means notifies the control means of the inspection level set by the information input by the input means; the control means, when notified of the first inspection level by the inspection means, determines the first number as the interval for performing the adjustment, and, when notified of the second inspection level by the inspection means, determines the second number as the interval for performing the adjustment; The input means can set an inspection level for each area on the inspection setting screen, the control means determines the number of sheets indicating the interval for performing the adjustment based on the highest inspection level among the inspection levels for each area; the second inspection level is higher than the first inspection level, and the second number of sheets is smaller than the first number of sheets. Imaging system.

Images