Image forming apparatus, display method for image forming apparatus, and program

Abstract

To provide a new mechanism that allows a user to check variations of hue in a print job related to the density in a plurality of printing steps.SOLUTION: An image forming apparatus comprises: a printing unit that performs printing on a recording medium according to a submitted print job; a first acquisition unit that acquires a first hue on an image carrier during printing processing; a second acquisition unit that acquires a second hue on the recording medium on which printing is performed; and a display unit that displays hue variation information on the basis of the acquired hues. The display unit displays first hue variation information based on the first hue and second hue variation information based on the second hue.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present disclosure relates to displaying variations in color tone in printed matter printed by an image forming apparatus. [Background technology]

[0002] In recent years, on-demand image forming devices (hereafter referred to as "printers") have shown improvements in image quality and productivity, and require less training time for operators, so they are increasingly being introduced as a replacement for offset printing machines. However, the image quality level of offset printing is high, and printers are only used in a limited way. To further expand the printer market, image quality equal to or better than that of offset printing is required. Of particular importance is improved color stability.

[0003] One color stabilization technology for printers is gradation correction control, which corrects the gradation of primary colors. A sensor reads the printed material (recording medium on which a toner image is recorded) printed by the printer, compares the read color with a target color, and determines the amount of correction required to bring the color closer to the target color. The input image data is corrected based on the determined amount of correction, thereby stabilizing the color during the print job. Furthermore, a technology is disclosed that displays the amount of correction to the user during printing, allowing the user to understand how the gradation correction control is working on the color difference between the target color and the color of the printed material. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-112771 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, gradation correction control based on color differences on the recording medium alone cannot stabilize the colors of a printer. For example, if there is no color difference on the image carrier in the printer but there is a color difference on the recording medium, correcting the amount of color material on the image carrier using gradation correction control can result in excessive color material on the image carrier, causing scattering and fluctuations in multi-colors.

[0006] When color variations occur during printing, it is necessary to select an appropriate correction control from multiple correction controls, such as gradation correction, maximum density correction, and secondary transfer voltage adjustment, depending on the cause of the color difference. However, in the past, users could check color differences on the recording medium, but they were unable to check color differences in printing processes other than on the recording medium. As a result, users were unable to determine which printing process was causing the color difference, and in some cases they performed the wrong correction control, resulting in further color differences.

[0007] The present invention has been made in consideration of at least one of the above problems, and provides a novel mechanism for allowing a user to check color variations during a print job related to density in a plurality of printing processes. [Means for solving the problem]

[0008] The image forming apparatus of the present invention comprises a printing unit that prints on a recording medium in accordance with an input print job, a first acquisition unit that acquires a first color on an image carrier during printing processing, a second acquisition unit that acquires a second color on the printed recording medium, and a display unit that displays color variation information based on the acquired color, and the display unit displays the first color variation information based on the first color and the second color variation information based on the second color. [Effects of the Invention]

[0009] The user can check color variations during a print job related to density in multiple printing processes. [Brief explanation of the drawings]

[0010] [Figure 1]FIG. 1 is a diagram showing an example of a network configuration including a printing system. [Figure 2] FIG. 2 is a cross-sectional view showing an example of the hardware configuration of the image forming apparatus. [Figure 3] FIG. 2 is a block diagram showing the internal configuration of an image forming apparatus, an external controller, and a client PC. [Figure 4] FIG. 4 is a schematic diagram showing how a color tone is acquired on an intermediate transfer belt, which is an image carrier. [Figure 5] FIG. 4 is a schematic diagram showing how a color tone is acquired on a recording medium. [Figure 6] A flowchart showing a processing procedure in an image inspection unit according to an embodiment. [Figure 7] An example of a screen for accepting settings for color variation detection. [Figure 8] An example screen showing color variations across multiple printing processes. [Figure 9] An example screen showing the user the necessary adjustments based on color variations. [Figure 10] 10 is an example of changing the toner density conditions displayed on a screen showing color variation. [Figure 11] An example of accepting a user instruction to refer to past data on a screen showing color variations. [Figure 12] 10 is a schematic diagram showing how a color is acquired on an intermediate transfer belt, which is an image carrier, when a plurality of patches for acquiring a color are arranged. [Figure 13] 10 is a schematic diagram showing how a color is acquired on a recording medium when a plurality of patches for acquiring a color are arranged. [Figure 14] 10 is a flowchart showing a processing procedure in an image inspection unit according to an embodiment. [Figure 15] 10 is an example of a screen that accepts the specification of a color acquisition position from input image data. [Figure 16] FIG. 4 is a schematic diagram illustrating a state in which a color tone is acquired on an intermediate transfer belt, which is an image carrier, in an embodiment. [Figure 17] 5A and 5B are schematic diagrams illustrating how colors on a recording medium are acquired in an embodiment. [Figure 18]6A and 6B are diagrams for explaining estimation of the amount of toner on a recording medium depending on the engine state in an embodiment. [Figure 19] An example of overlaying the acquired colors and differences. [Figure 20] An example of displaying color variations using icons based on the acquired color. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0012] First Embodiment In this embodiment, in addition to an input image toner image based on an input image on intermediate transfer belt 308, which is an image carrier of printing unit 107 (described later), a patch toner image whose color can be measured is formed at the edge of the recording medium, and the color on the image carrier is acquired by density sensor 310. Furthermore, an image based on the input image toner image and the patch toner image is formed on the recording medium, and the color of the patch on the recording medium is acquired by image reading unit 331. Density sensor 310 and image reading unit 331 are one embodiment of an acquisition unit that acquires color.

[0013] In this embodiment, the toner amount is used as an example of color. Note that color is not limited to the above example. Any scale capable of expressing the color difference of an image may be used, such as lightness, saturation, or hue. The difference in color between a reference color and the color resulting from actual printing is referred to as color variation. For lightness, saturation, and hue, color variation is the difference in lightness, saturation, and hue, respectively. The color variation in each printing process is obtained from two colors acquired in different printing processes and displayed during the print job. By displaying the color variation in different printing processes, the user is notified in real time of the presence or absence of a printing process that may be causing the color variation.

[0014] In this embodiment, an example of acquiring the color variation due to the amount of applied toner will be described, but it is desirable to acquire the color variation in an optimal format depending on the color to be acquired. For example, when acquiring the above-mentioned lightness, saturation, and hue as the color, the color difference used as a measure of color difference in the field of color science can be used as the variation. A detailed implementation method will be described below.

[0015] <Overall system configuration> Fig. 1 is a diagram showing an example of a network configuration including a printing system (image processing system) according to this embodiment. As shown in Fig. 1, the printing system 100 includes an image forming apparatus 101 and an external controller 102. The image forming apparatus 101 and the external controller 102 are communicatively connected via an internal LAN 105 and a video cable 106. The external controller 102 is communicatively connected to a client PC 103 via an external LAN 104.

[0016] The client PC 103 can issue a print instruction to the external controller 102 via the external LAN 104. A printer driver is installed in the client PC 103, and has the function of converting image data to be printed into a page description language (PDL) that can be processed by the external controller 102. A user who wishes to print can issue a print instruction via the printer driver from various applications installed on the client PC 103 by operating the client PC 103. The printer driver transmits PDL data, which is print data, to the external controller 102 based on the print instruction from the user. Upon receiving the PDL data from the client PC 103, the external controller 102 analyzes and interprets the received PDL data. Based on the interpretation result, the external controller 102 performs rasterization processing to generate a bitmap image (print image data) with a resolution matching the image forming apparatus 101, and issues a print instruction by submitting a print job to the image forming apparatus 101.

[0017] Next, the image forming apparatus 101 will be described. In the image forming apparatus 101, devices with multiple different functions are connected and configured to be capable of complex printing processes such as bookbinding. The image forming apparatus 101 has a printing unit 107 (image forming unit), an inserter 108, an image inspection unit 109, a stacker 110, and a finisher 111. Each module will be described below.

[0018] The printing unit 107 generates an image including a patch on the edge of the recording medium in accordance with the print job, and ejects the printed recording medium with the image printed on it. The printed recording medium ejected from the printing unit 107 is transported inside each device in the order of the inserter 108, image inspection unit 109, stacker 110, and finisher 111. The printing unit 107 also includes a density sensor 310 that acquires color tones on the image carrier, which is the transport path during the process of printing the image on the recording medium, and acquires color tones on the image carrier during the printing process.

[0019] In this embodiment, the image forming apparatus 101 of the printing system 100 is an example of an image forming apparatus, but the printing unit 107 included in the image forming apparatus 101 may also be referred to as the image forming apparatus. The printing unit 107 forms (prints) an image using toner (color material) on a recording medium fed and transported from a paper feed unit disposed below the printing unit 107.

[0020] Furthermore, when the printing unit 107 receives an image adjustment instruction from a user operation or an image inspection unit 109 (described later), it prints a test chart corresponding to the image adjustment from a group of test charts stored in advance. Furthermore, the printed matter is acquired by an image reading unit 331 (described later), and image adjustment is performed based on the acquired results. The image adjustment is performed by an image adjustment means in the printing unit 107. The image adjustments performed by the image adjustment means include main scanning unevenness correction to adjust the uniformity of image density, maximum density correction, automatic gradation correction to maintain maximum density and monochromatic gradation, adjustment of secondary transfer voltage, and automatic color tone correction to adjust for variations in multi-colors.

[0021] The inserter 108 is a device for inserting an insertion sheet, and can insert an insertion sheet at any position in the group of sheets printed by the printing unit 107 and transported.

[0022] The image inspection unit 109 acquires the color on the recording medium using the image reading unit 331 based on the printed recording medium that has been printed by the printing unit 107 and transported through a transport path. The image inspection unit 109 acquires the acquired color variation on the recording medium and the color variation on the image carrier acquired by a density sensor 310 provided in the printing unit 107, and displays the color variation on the display unit 215, which will be described later. Furthermore, in addition to the two color variations on the recording medium and the image carrier, the image inspection unit 109 displays a comparison result that is the difference between the two color variations, and determines whether image adjustment by the printing unit 107 is necessary. The method of acquiring the color variation and the determination process for determining the need for image adjustment will be described later in detail.

[0023] The stacker 110 is a device capable of stacking a large number of printed recording media. The finisher 111 is a device that can perform finishing processes such as stapling, punching, saddle stitching, etc. on the conveyed printed recording medium. The recording medium processed by the finisher 111 is discharged to a predetermined discharge tray.

[0024] 1, an external controller 102 is connected to the image forming apparatus 101, but this embodiment can also be applied to a different configuration. For example, a configuration may be used in which the image forming apparatus 101 is connected to an external LAN 104, and print data is sent from a client PC 103 to the image forming apparatus 101 without going through the external controller 102. In this case, data analysis and rasterization of the print data are performed by the image forming apparatus 101.

[0025] <Hardware Configuration of Image Forming Apparatus 101> 2 is a cross-sectional view showing an example of the hardware configuration of the image forming apparatus 101. A specific example of the operation of the image forming apparatus 101 will be described below with reference to FIG.

[0026] The printing unit 107 is equipped with multiple paper feed decks. In this embodiment, two types of decks, paper feed decks 301 and 302, are provided. Each paper feed deck stores various recording media (paper). Of the recording media stored in each paper feed deck, the uppermost recording medium is separated one by one and fed to a conveying path 303. Furthermore, each of the image forming stations 304 to 307 includes a photosensitive drum (photoconductor) and forms a toner image on the photosensitive drum using toner of a different color. Specifically, the image forming stations 304 to 307 form a toner image using toner of yellow (Y), magenta (M), cyan (C), and black (K), respectively.

[0027] The toner images of each color formed in the image forming stations 304 to 307 are transferred onto the intermediate transfer belt 308 in order, superimposed on top of each other (primary transfer). The toner images transferred onto the intermediate transfer belt 308 are transported to a secondary transfer position 309 as the intermediate transfer belt 308 rotates. In this embodiment, in addition to the toner images based on input image data, patches for acquiring color are formed on the intermediate transfer belt 308. The formed patches are measured by a density sensor 310, thereby acquiring the color on the intermediate transfer belt 308.

[0028] The density sensor 310 is composed of a light-emitting element and a light-receiving element, and the light emitted from the light-emitting element is reflected by the surface of the intermediate transfer belt 308, which is an image carrier, and the reflected light is measured by the light-receiving element. A luminance value is obtained from the ratio of the light emitted from the light-emitting element to the reflected light. A conversion table is provided for converting the luminance value into the amount of applied toner, and the toner amount is obtained from the luminance value based on the conversion table. The process of obtaining the toner amount from the luminance value will be described later.

[0029] At the secondary transfer position 309, a toner image is transferred from the intermediate transfer belt 308 onto the recording medium conveyed along the conveying path 303 (secondary transfer). After the secondary transfer, the recording medium is conveyed to a fixing unit 311. The fixing unit 311 includes a pressure roller and a heating roller. As the recording medium passes between these rollers, heat and pressure are applied to the recording medium, thereby performing a fixing process that fixes the toner image onto the recording medium. After passing through the fixing unit 311, the recording medium is conveyed along a conveying path 312 to a connection point 315 between the printing unit 107 and the image inspection unit 109. In this way, a color image is formed (printed) on the recording medium.

[0030] If further fixing processing is required depending on the type of recording medium, the recording medium that has passed through fixing unit 311 is guided to conveyance path 314 provided with fixing unit 313. Fixing unit 313 performs further fixing processing on the recording medium conveyed along conveyance path 314. The recording medium that has passed through fixing unit 313 is conveyed to connection point 315. Furthermore, if a double-sided printing operation mode is set, an image is printed on the first side, and the recording medium conveyed along conveyance path 312 or conveyance path 314 is guided to reversing path 316. The recording medium that has been reversed by reversing path 316 is guided to double-sided conveyance path 317 and conveyed to secondary transfer position 309. As a result, a toner image is transferred to the second side of the recording medium, which is opposite to the first side, at secondary transfer position 309. Thereafter, the recording medium passes through fixing unit 311 (and fixing unit 313), completing the formation of a color image on the second side of the recording medium. After the image formation (printing) in the printing unit 107 is completed, the printed recording medium is transported to the connection point 315 and then transported into the inserter .

[0031] The inserter 108 inserts insertion sheets. The inserter 108 is equipped with an inserter tray 321, and merges insertion sheets fed to the inserter tray 321 with the transport path via a paper transport path 322. This makes it possible to insert insertion sheets at any position in a series of recording media transported from the printing unit 107 and transport them to subsequent devices. The recording media that have passed the inserter 108 are transported to the image inspection unit 109.

[0032] The image inspection unit 109 includes an image reading unit 331 having a CIS (Contact Image Sensor) on a transport path 330 along which the printed recording medium from the inserter 108 is transported. The image reading unit 331 is positioned so as to read the top surface (first surface) of the recording medium. Note that the image reading unit 331 may be configured with, for example, a CCD (Charge Coupled Device) or a line scan camera instead of a CIS. The image reading unit 331 acquires signal values ​​of a color image in three RGB channels as color tones. It includes a conversion table for converting RGB values ​​into toner application amounts, and acquires the toner amounts from the RGB values ​​based on the conversion table. The process of acquiring the toner amounts from RGB values ​​will be described in detail later.

[0033] The image inspection unit 109 acquires color variations from the colors on the intermediate transfer belt and on the printed recording medium in different printing processes, and displays them on the display unit 215 to notify the user of real-time color variations during the print job. Furthermore, based on the color variations in each printing process and the difference in color variations between printing processes, it also determines the need for image adjustment in the printing unit 107. The recording media that have passed the image inspection unit 109 are transported in order to the stacker 110. Specific processing by the image inspection unit 109 will be described later.

[0034] The stacker 110 includes a stack tray 341 as a tray on which printed recording media transported from the image inspection unit 109, which is arranged upstream in the transport direction of the printed recording media, are stacked. The printed recording media that have passed the image inspection unit 109 are transported along a transport path 344 within the stacker 110. The printed recording media transported along the transport path 344 are guided to a transport path 345, whereby the printed recording media are stacked on the stack tray 341. The stacker 110 further includes an escape tray 346 as a paper discharge tray.

[0035] In this embodiment, the escape tray 346 is used to discharge printed materials that have been determined to have color variations by the image inspection unit 109. Printed materials that have been detected to have color variations and are transported along the transport path 344 are guided to the transport path 347 and transported to the escape tray 346. Printed recording media that are transported in the stacker 110 without being stacked or ejected are transported via the transport path 348 to the subsequent finisher 111. The stacker 110 further includes an inverting unit 349 for inverting the orientation of the printed recording media being transported. The inverting unit 349 is used, for example, to ensure that the orientation of the recording media input into the stacker 110 is the same as the orientation of the printed recording media when they are stacked on the stack tray 341 and output from the stacker 110. Note that the inverting operation by the inverting unit 349 is not performed on printed recording media that are not stacked in the stacker 110 and transported to the finisher 111.

[0036] The finisher 111 executes a finishing function designated by a user on a printed recording medium conveyed from an image inspection unit 109 disposed upstream in the conveyance direction of the printed recording medium. In this embodiment, the finisher 111 has finishing functions such as a staple function (one-point or two-point binding), a punch function (two-hole or three-hole), and a saddle stitch binding function. The finisher 111 includes two paper output trays 351 and 352.

[0037] When finishing processing is not performed by the finisher 111, the printed recording medium transported to the finisher 111 is discharged to a paper output tray 351 via a transport path 353. When finishing processing such as stapling is performed by the finisher 111, the printed recording medium transported to the finisher 111 is led to a transport path 354. The finisher 111 uses a finishing processing unit 355 to perform finishing processing specified by the user on the printed recording medium transported on the transport path 354. Then, the printed recording medium that has undergone finishing processing is discharged to a paper output tray 352.

[0038] <Functional configuration diagram> FIG. 3 is a schematic functional block diagram of the image forming apparatus 101, the external controller 102, and the client PC 103. As shown in FIG. The printing unit 107 of the image forming apparatus 101 includes a communication I / F (interface) 201, a network I / F 204, a video I / F 205, a CPU 206, a memory 207, an HDD unit 208, and a UI display unit 202. The printing unit 107 further includes a print unit 203 and a density sensor 310. These are connected to each other via a system bus 209 so as to be able to send and receive data. The communication I / F 201 is connected to the inserter 108, image inspection unit 109, stacker 110, and finisher 111 via a communication cable 260.

[0039] The CPU 206 communicates via the communication I / F 201 to control each device. The network I / F 204 is connected to the external controller 102 via the internal LAN 105 and is used for communication of control data, etc. The video I / F 205 is connected to the external controller 102 via a video cable 106 and is used for communication of data, such as image data. Note that the printing unit 107 (image forming apparatus 101) and the external controller 102 may be connected via only the video cable 106, as long as the external controller 102 can control the operation of the image forming apparatus 101. The HDD unit 208 stores various programs and data. The CPU 206 controls the overall operation of the printing unit 107 by executing programs stored in the HDD unit 208. The memory 207 stores programs and data required for the CPU 206 to perform various processes. The memory 207 operates as a work area for the CPU 206.

[0040] The UI display unit 202 receives various setting inputs and operation instructions from the user, and is used to display various information such as setting information and the processing status of a print job, etc. In this embodiment, the UI display unit 202 is used to switch the setting of whether or not to perform color variation detection during printing.

[0041] Furthermore, under the control of the CPU 206, the printing unit 107 measures the color on the intermediate transfer belt 308 in the printing unit 203 with a density sensor 310. The density sensor 310 measures a luminance value as the color. The CPU 206 stores the luminance value measured by the density sensor 310 in the memory 207.

[0042] 4(a) and 4(b) are schematic diagrams showing the relationship between the toner image on the intermediate transfer belt 308 and the density sensor 310 when acquiring a luminance value. FIG. 4(a) is a bird's-eye view of the intermediate transfer belt 308 from a position facing the belt, and FIG. 4(b) is a cross-sectional view from a position parallel to the belt 308. In addition to the toner image 502 corresponding to the input image, patches 501 for measuring color are placed at the rear end of the recording medium. The number of patches 501 is the same as the number of toner colors. In this embodiment, since the printing unit 107 uses four colors of toner (CMYK), four different patches are placed. Each patch is a single-color patch with an area ratio of 50%. The density sensor 310 irradiates the patches 501 with light and measures the reflected light to acquire a luminance value, which represents the color on the image carrier. The area ratio is the amount of toner applied per unit area and is an index representing toner concentration. The stored luminance value is referenced by the image inspection unit 109, which will be described later. Detailed processing will be described later.

[0043] The image inspection unit 109 includes a communication I / F 211, a CPU 212, a memory 213, an HDD unit 214, an image reading unit 331, a determination processing unit 216, and a UI display unit 215. These devices are connected via a system bus 209 so that they can send and receive data to and from each other. The communication I / F 211 is connected to the printing unit 107 via a communication cable 260. The CPU 212 performs communication necessary for controlling the image inspection unit 109 via the communication I / F 211. The CPU 212 controls the operation of the image inspection unit 109 by loading a control program stored in the HDD unit 214 into the memory 213 and executing it. The HDD unit 214 stores a control program for the image reading unit 331 and a processing program executed by the determination processing unit 216 to determine the need for image adjustment in the printing unit 107. The image reading unit 331 acquires RGB values, which represent the color of the conveyed printed matter, in accordance with instructions from the CPU 212.

[0044] 5(a) and (b) are schematic diagrams showing the relationship between the toner image on the recording medium and the image reading unit 331 when acquiring RGB values. FIG. 5 shows an example in which the toner image on the intermediate transfer belt 308 shown in FIG. 4 is transferred and fixed onto the recording medium 503 and then transported to the transport path 330. As with FIG. 4, FIG. 5(a) is a bird's-eye view from a position facing the transport path 330, and FIG. 5(b) is a cross-sectional view seen from a position parallel to the transport path 330. Patches 501 formed on the recording medium 503 are read by the image reading unit 331. The image reading unit 331 acquires RGB signal values ​​that represent the color of each patch.

[0045] The CPU 212 converts the RGB values ​​acquired by the image reading unit 331 and the luminance values ​​acquired by the density sensor 310 into toner amounts, and acquires the amount of variation from the difference from the target toner amount. Furthermore, the CPU 212 determines the need for image adjustment in the printing unit 107 based on whether or not there is a variation in color on the image carrier during printing processing that exceeds a reference value, whether or not there is a variation in color on the recording medium that exceeds a reference value, and the difference in color variation between printing processes.

[0046] The UI display unit 215 displays color variations on the image carrier and color variations on the recording medium 503. It is also used to display the difference between the two color variations, the color variations and the determination result of the need for image adjustment based on the difference between the two color variations, and adjustment instructions. The UI display unit 215 also serves as a user operation instruction unit for the image inspection unit 109, and is operated by the user to accept various instructions. For example, it accepts instructions for image adjustment and instructions to change the display content.

[0047] The inserter 108 performs a process of inserting the inserted sheet fed to the inserter tray 321. The inserter 108 controls the transport of the printed recording medium to the image inspection unit 109 connected downstream. The stacker 110 controls whether the printed recording medium transported along the transport path is discharged to a stack tray, discharged to an escape tray, or transported to a finisher 111 connected downstream in the transport direction of the printed recording medium. The finisher 111 controls the transport and discharge of printed recording media, and performs finishing processes such as stapling, punching, or saddle stitching.

[0048] The external controller 102 includes a CPU 251, a memory 252, an HDD unit 253, a keyboard 256, a display unit 254, network I / Fs 255 and 257, and a video I / F 258. These devices are connected via a system bus 259 so that they can send and receive data to and from each other. The CPU 251 executes programs stored in the HDD unit 253 to control the overall operation of the external controller 102, such as receiving print data from the client PC 103, RIP processing, and sending print data to the image forming apparatus 101. The memory 252 stores programs and data required for the CPU 251 to perform various processes. The memory 252 operates as a work area for the CPU 251.

[0049] The HDD unit 253 stores various programs and data. The keyboard 256 is used for inputting operation instructions for the external controller 102 from the user. The display unit 254 is, for example, a display, and is used for displaying information about applications currently running in the external controller 102 and an operation screen. The network I / F 255 is connected to the client PC 103 via the external LAN 104 and is used for communicating data such as print instructions. The network I / F 257 is connected to the image forming apparatus 101 via the internal LAN 105 and is used for communicating data such as print instructions. The external controller 102 is configured to be able to communicate with the printing unit 107, the inserter 108, the image inspection unit 109, the stacker 110, and the finisher 111 via the internal LAN 105 and a communication cable 260. The video I / F 258 is connected to the image forming apparatus 101 via the video cable 106 and is used for communicating data such as image data (print data).

[0050] The client PC 103 includes a CPU 261, a memory 262, an HDD unit 263, a display unit 264, a keyboard 265, and a network I / F 266. These devices are connected via a system bus 269 so that they can send and receive data to and from each other. The CPU 261 controls the operation of each device via the system bus 269 by executing a program stored in the HDD unit 263. This enables various processes to be performed by the client PC 103. For example, the CPU 261 generates print data and issues print instructions by executing a document processing program stored in the HDD unit 263. The memory 262 stores programs and data required for the CPU 261 to perform various processes. The memory 262 operates as a work area for the CPU 261.

[0051] The HDD unit 263 stores various applications such as a word processing program, programs such as a printer driver, and various data. The display unit 264 is, for example, a display, and is used to display information about applications running on the client PC 103 and an operation screen. The keyboard 265 is used to input operation instructions for the client PC 103 from the user. The network I / F 266 is communicably connected to the external controller 102 via the external LAN 104. The CPU 261 communicates with the external controller 102 via the network I / F 266.

[0052] <Processing flow of the determination processing unit 216> The determination process in the image inspection unit 109 according to this embodiment will be described with reference to FIG. 6. FIG. 6 is a flowchart showing the processing procedure in which the image inspection unit 109 acquires color variations during a print job executed by the printing unit 107 and displays the results. Note that FIG. 6 shows the overall flow from setting to execute color variation detection to the end of the print job. The processing of each step in FIG. 6 is realized by the CPU 206 of the printing unit 107 and the CPU 212 of the image inspection unit 109 reading a program stored in the HDD unit 208 or HDD unit 214 into the memory 207 or memory 213 and executing it. The step numbers of each process included in the flowchart are indicated by numbers beginning with "S." The same applies to the following flowcharts.

[0053] First, in S601, the CPU 206 accepts a request to perform color variation detection based on a user instruction on the UI display unit 202. FIG. 7 shows an example of a screen for accepting user instructions. FIG. 7(a) shows the initial screen before accepting a user instruction. Until a check instruction is received in 701a, the input section for the color variation standard for each color material is grayed out and input is not possible. 701a is checked and the screen after the user instruction is received is shown in schematic diagram 7(b). A check mark is displayed in 701b, indicating that the user instruction has been received. Furthermore, the input section for the variation standard for each color material is ungrayed out, and the user's instruction for the variation standard value is accepted. The variation standard value is input by the user using a numeric keypad or the like (not shown). After the user has accepted a request to perform color variation detection and the print job is executed, the process proceeds to S602 and subsequent steps.

[0054] The processing of S602 to S611 is performed on a page-by-page basis. If the print job is data consisting of multiple pages, S602 to S611 are repeatedly executed for each page until printing of all pages included in the print job is completed.

[0055] In S602, the CPU 206 controls the print unit 203 to form a toner image corresponding to the input image data and the color acquisition patch 501 on the photosensitive member, and transfer it to the intermediate transfer belt 308. The toner image transferred to the intermediate transfer belt 308 is transported to the position of the density sensor 310 as the intermediate transfer belt 308 rotates, and the process proceeds to S603.

[0056] In S603, the CPU 206 controls the density sensor 310 to acquire the luminance value of the color acquisition patch 501. The acquired luminance value is stored in the memory 207. When acquisition of the luminance value is completed, the process proceeds to S604.

[0057] In S604, the CPU 206 controls the print unit 203 to transport the toner images (501, 502) and form (print) a color image on the recording medium. Once the image is formed on the recording medium and transported to a position where the color can be read by the image reading unit 331, the process proceeds to S605. Steps from S605 onwards are performed by the image inspection unit 109.

[0058] In S605, the CPU 212 controls the image reading unit 331 to acquire the RGB values ​​of the color acquisition patch 501. The acquired RGB values ​​are stored in the memory 213. When the image reading unit 331 has completed acquisition of the RGB values ​​acquired on the recording medium, the process proceeds to S606.

[0059] In S606, the CPU 212 acquires the brightness value of the density sensor 310 acquired on the intermediate transfer belt 308, which is stored in the memory 207 of the printing unit 107, and converts it into a toner amount. Next, the converted toner amount and a target toner amount (target toner amount T 50% ) and the fluctuation (difference) between the toner amount and the fluctuation reference value T th and judge whether the fluctuation (difference) in the amount of toner on the intermediate transfer belt 308 exceeds the reference value. The fluctuation (difference) in the amount of toner is one embodiment of the fluctuation in color tone.

[0060] First, the conversion process from luminance values ​​to toner amounts will be described. The conversion from luminance values ​​to toner amounts is performed using a known one-dimensional LUT. In this embodiment, a one-dimensional LUT indicating the relationship between luminance values ​​and toner amounts is stored in advance in the HDD unit 214 for each toner color, and the CPU 212 performs the conversion process by referencing the one-dimensional LUT. An example of a one-dimensional LUT is shown in Table 1. Table 1 shows an example of K toner with 8-bit input and output. The one-dimensional LUT stores output values ​​for input values ​​at equal intervals. When an intermediate value not stored in the LUT is given, the output value is obtained based on a known interpolation calculation process. A test patch in which a patch with varying toner amounts is recorded on an image carrier is measured using a gravimeter. Based on the measurement results, a toner concentration of 0.50 [mg / cm 2] is normalized to 8 bits so that it becomes 255, and is stored in the HDD unit 214. [Table 1]

[0061] Next, the converted toner amount and the target toner amount (target toner amount T 50% ) is acquired from the brightness value. ITB and the target toner amount T 50% Finally, the obtained toner amount fluctuation and the fluctuation reference value T th The absolute value of the toner amount fluctuation is compared with the fluctuation reference value T th If the value exceeds the reference value, it is determined that the toner amount has fluctuated beyond the fluctuation reference value. ITB and the target toner amount T 50% , fluctuation reference value T th The following judgment formula (1) is used to judge whether or not there is a fluctuation in the toner amount on the image carrier that exceeds the fluctuation reference value. If the fluctuation in the toner amount exceeds the fluctuation reference value and the density is higher than the target, it is set to 1; if it exceeds the fluctuation reference value and the density is lower than the target, it is set to -1. If the color fluctuation is equal to or lower than the fluctuation reference value, it is set to 0. One of these three values ​​is the judgment result R on the image carrier. ITB Let R ITB is performed for each toner color, but the same determination is performed, so the explanation will be omitted. TIFF2025186914000003.tif38170 judgment result R ITB is calculated and stored in the memory 213, the process proceeds to S607.

[0062] Next, S607, which acquires color variation information (the difference between the target value and the acquired toner amount for each page) on the recording medium 503, will be described. In S607, the RGB values ​​stored in the memory 213 are acquired by the CPU 212 and converted into toner amounts. Next, the converted toner amounts are compared with the target toner amount (target toner amount T 50%) and the fluctuation (difference) between the toner amount and the fluctuation reference value T th The fluctuation (difference) in the amount of toner on the recording medium 503 is compared with the fluctuation reference value T th Determine whether it exceeds

[0063] First, the conversion from RGB values ​​to toner amounts will be described. The conversion from RGB values ​​to toner amounts uses a known 3D LUT designed based on the relationship between RGB values ​​acquired by the image reading unit 331 and toner amounts. In this embodiment, a 3D LUT indicating the relationship between RGB values ​​and toner amounts is stored in advance in the HDD unit 214 for each toner, and the CPU 212 performs the conversion process by referencing the 3D LUT. An example of a 3D LUT is shown in Table 2. Table 2 shows an example of a K toner with 8-bit input and output. The 3D LUT stores output values ​​for evenly spaced input values. When an intermediate value not stored in the LUT is given, the output value is obtained based on a known interpolation calculation process. The LUT is created by measuring the toner amount, which is the weight of an unfixed toner image recorded on a standard recording medium 503 assumed by the printing unit 107 using a gravimeter, using patches with varying toner amounts. Similar to the color variation information on the intermediate transfer belt (image carrier) 308, a toner amount of 0.50 [mg / cm] is calculated based on the measurement results. 2 ] is 255, and is stored in the HDD unit 214. The relationship held in the 3D LUT varies depending on the basis weight and surface properties of the paper used as the recording medium 503. For this reason, it is more preferable to be able to calibrate based on the recording medium 503 used by the user, as disclosed in Japanese Patent Application Laid-Open No. 2007-272112. Note that, although an example of acquiring the toner amount using all RGB values ​​has been described in this embodiment, it is not limited to the above example. Any method may be used as long as the toner amount is acquired from the RGB values, and for example, a method of acquiring it from a signal value that is complementary to the toner color may be used. [Table 2]

[0064] Next, the converted toner amount and the target toner amount (target toner amount T 50%The variation in the toner amount is calculated by calculating the difference between the toner amount T paper and the target toner amount T 50% Finally, the obtained toner amount fluctuation and the fluctuation reference value T th The absolute value of the toner amount fluctuation is compared with the fluctuation reference value T th If the value exceeds the reference value, it is determined that the toner amount has fluctuated beyond the fluctuation reference value. paper and the target toner amount T 50% , fluctuation reference value T th The following judgment formula is used to judge whether there is a fluctuation exceeding the fluctuation reference value on the recording medium 503. The judgment result is 1 if the fluctuation reference value is exceeded and the density is increased relative to the target, and -1 if the fluctuation reference value is exceeded and the density is decreased relative to the target. If the fluctuation in the toner amount is equal to or less than the fluctuation reference value, it is 0. One of these three values ​​is used as the judgment result R on the recording medium. paper Let R paper is performed for each toner color, but the same determination is performed, so the explanation will be omitted. TIFF2025186914000005.tif37170 judgment result R paper is calculated and stored in the memory 213, the process proceeds to S608.

[0065] Next, a description will be given of step S608, in which the difference in the toner amount fluctuation between the printing processes is acquired and it is determined whether or not a difference in the toner amount fluctuation that exceeds the reference value occurs between the printing processes. ITB and T obtained in S606 paper In this embodiment, the comparison is performed and the difference is obtained as the comparison result. Whether the obtained difference exceeds the fluctuation reference value is determined by the following determination formula (3). If the fluctuation reference value is exceeded, T paper Compared to T ITB If the concentration is increasing, it is 1, and the fluctuation standard value is exceeded. ITB Compared to T paper If the concentration is increasing, set it to -1. paper and T ITBIf the difference is below the standard, it is set to 0. One of these three values ​​is used as the judgment result R of the difference in the toner amount fluctuation between printing processes. diff Let R diff is performed for each toner color, but the same determination is performed, so the explanation will be omitted. TIFF2025186914000006.tif39170 judgment result R diff Once calculated, it is stored in the memory 213 and the process proceeds to S608.

[0066] In step S609, the CPU 212 controls the UI display unit 215 and presents the determination results to the user. Examples of screen displays are shown in FIG. 8. FIG. 8(a) shows the state in which up to page 5 of the print job has been printed. The displayed color and the displayed variations can be changed by switching the radio buttons in the display settings. In FIG. 8(a), the display color shows the results for K toner, and an example is shown in which the color variation on the intermediate transfer belt 308 and the color variation on the recording medium 503 are simultaneously displayed. Note that the above display configuration is merely an example and is not limiting. As a more preferred example, an example is shown in which the color variation on the image carrier and the color variation on the recording medium are displayed on a single screen. However, it is sufficient if only one type of color variation is displayed on the screen and the displayed items can be switched by setting. A configuration in which multiple colors are displayed simultaneously is also possible. Each color may be displayed side by side, or the plotted points may be displayed in different colors and overlapped. Furthermore, the user may be able to freely change not only the items to be displayed, but also the graph size and layout of each displayed color variation.

[0067] The display area 801 shows the target toner amount T 50% is set as the reference value of 0, and the target toner amount T 50% and the amount of toner on the image carrier T ITB Similarly, the display area 802 shows the relationship between the target toner amount T 50% and the toner amount T on the recording medium paper The display area 803 shows the relationship between the target toner amount T 50% and the toner amount T on the image carrier. ITB and the toner amount T on the recording medium paperAs shown in Figure 8(a), it is possible to compare and check color variations across multiple printing processes within a print job, making it easy to identify the printing process that is causing the color variations. Furthermore, Figure 8(b) shows the state when the number of printed pages has reached 10. A plot is added in real time for each number of printed pages, making it possible to notice color variations and make adjustments. Also, 804 is the variation reference value T th From the relationship between the fluctuation reference value and the color fluctuation, it is easy to determine whether the color fluctuation is at a level that requires image adjustment.

[0068] In this embodiment, as a more preferred example, a process is added to automatically determine whether image adjustment is necessary for the printing unit 107 based on the color variation for each printing process and the difference in color variation between printing processes. The above determination process corresponds to S610 and S611. After updating the display in S609, the process proceeds to S610. Whether image adjustment is necessary may simply be indicated, or the type of adjustment required may be indicated. Furthermore, adjustment values ​​for adjusting the color may also be indicated.

[0069] In S610, the CPU 212 determines the result R ITB and the judgment result R on the recording medium. paper and the result of determining the difference between the color variation on the image carrier and the color variation on the recording medium R diff Based on this, the necessity of image adjustment is judged. ITB , R paper , R diff The image adjustment information required for the combination of values ​​is stored in advance in the HDD unit 214 and is referenced for the determination. Table 3 shows an example of the combination information. [Table 3]

[0070] As shown in Table 3, ID=1, R on the image carrier ITB There is a color variation that exceeds the standard on the paperIf this occurs even when the image quality is low, there is a high possibility that color variations have occurred in the toner image on the intermediate transfer belt 308, which is an image carrier. Therefore, it is desirable to perform gradation correction processing to correct the toner image on the intermediate transfer belt 308. In the above case, in S611, the CPU 212 controls the UI display unit 215 to instruct the user to perform gradation correction processing. FIG. 9(a) shows an example of a screen that instructs the user in the state of ID=1 in Table 3. As shown in display area 901a, adjustment instructions corresponding to the variations are displayed to the user together with a highlight icon.

[0071] Also, as shown in ID=4 in Table 3, R ITB Although there is no color variation in the R on the recording medium paper If a density decrease occurs in step 901b, it is highly likely that a fluctuation occurred during the process of transferring the toner image from the intermediate transfer belt 308 to the recording medium. Therefore, it is desirable to perform a secondary transfer voltage adjustment process to adjust the amount of toner in the transfer process. In the above case, in step S611, the CPU 212 controls the UI display unit 215 to instruct the user to execute the secondary transfer voltage adjustment process. Figure 9(b) shows an example of a screen that instructs the user in the state where ID=1 in Table 3 is displayed. As shown in display area 901b, an adjustment instruction is displayed to the user together with a highlight icon.

[0072] Furthermore, taking ID=5 in Table 3 as an example, R ITB Although color variations occur in the R on the recording medium, paperNo color variation occurs in the image forming process. In such a case, adjustments are likely necessary in both the toner image forming process and the toner image transferring process. Therefore, in the example of ID=5, it is desirable to first correct the toner image formation process, which is upstream of the printing process, by gradation correction, and then adjust the toner image transferring process by adjusting the secondary transfer voltage. In this case, in S611, the CPU 212 controls the UI display unit 215 to instruct the user that gradation correction processing and secondary transfer voltage adjustment processing are necessary and to perform the gradation correction processing first. Note that the instruction to adjust the image for color variation described above is merely an example, and the effects of the present invention are not limited to this example. For example, if color variation is not reduced even after gradation correction and secondary transfer voltage adjustment, a configuration may be included in which adjustments are made in the process of fixing the toner image on the recording medium 503. Note that in the fixing process, color can be stabilized by adjusting the temperature of a fixing member (not shown) and the pressure with which the fixing member is pressed against the recording medium 503.

[0073] In this embodiment, an example has been shown in which instructions for image adjustment are displayed based on the determination result, but this is just one example of using the determination result and is not limited to adjustment instructions. It is sufficient if measures for reducing variations occurring in the printing unit 107 can be implemented based on the determination result. For example, if the color variation exceeds a reference value, the printing process in the printing unit 107 may be stopped and image adjustment may be automatically performed. Furthermore, the items presented are not limited to only the types of image adjustment. Based on the color variation, adjustment values ​​required to reduce the color variation may be presented.

[0074] As described above, the printing unit 107, which performs multiple types of image adjustment, is equipped with an acquisition unit that acquires the color on the intermediate transfer belt 308 during the printing process in addition to the color on the recording medium 503, and acquires the color in multiple printing processes. Furthermore, the color variation in each process is calculated based on the color acquired in the multiple processes, and the color variation on the intermediate transfer belt 308 and the color variation on the recording medium 503 are displayed on the UI. By displaying the color variation on the intermediate transfer belt 308 during the printing process and the color variation on the recording medium 503 and comparing the color variation between multiple printing processes, the user can grasp in which printing process the color variation is occurring.

[0075] <Modification of the first embodiment> In this embodiment, an example has been described in which the intermediate transfer belt 308 is used as the image carrier, but the image carrier is not limited to the intermediate transfer belt 308. It is sufficient if the toner image is from a printing process different from that on the recording medium, and a density sensor may be installed opposite the photosensitive drum to measure the color tone using the photosensitive drum as the image carrier.

[0076] Note that, in this embodiment, an example has been described in which color tones are acquired in multiple printing processes and the variations in the acquired color tones are displayed. However, the variations displayed are not limited to color tones. For example, temperature and humidity within the printing unit 107 are factors that affect color tones. When color tones vary due to the effects of temperature and humidity, implementing measures such as the gradation correction described above may not result in sufficient improvement. In such cases, it is desirable to install a thermo-hygrometer within the printing unit 107 (inside the image forming apparatus) and measure the temperature and humidity in real time, and use the results as the criteria for determination in S610. Table 4 shows an example of combination information with temperature and humidity added. The thermo-hygrometer is one embodiment of the temperature and humidity acquisition unit. The difference from Table 3 is that temperature and humidity have been added as criteria for determination. As shown by ID=7, if there are temperature and humidity variations and variations occur in each printing process, the user is instructed to adjust the room temperature. [Table 4]

[0077] In this embodiment, an example has been described in which only patches with an area ratio of 50% are arranged and color variation at a specific density is confirmed, but the density at which color variation is confirmed is not limited to the above example. It is more desirable to arrange and acquire patches with a plurality of area ratios. For example, 10 patterns from 10% to 100% are acquired in 10% increments, and the density at which color variation information is displayed can be switched according to a user's instruction, as shown in the display setting 1001 in FIG. 10 .

[0078] In this embodiment, an example has been described in which fluctuations within a print job are displayed in real time, but it is more preferable to have a configuration in which it is possible to check whether the results of past color fluctuations were satisfactory. For example, it is possible to have a function in which the color fluctuations displayed in S609 are stored not only in the memory 213 but also in the HDD unit 214 (storage unit), and the past color fluctuations are displayed on the UI display unit 215 in response to a user instruction.

[0079] FIG. 11 shows an example of a screen used when a user specifies a time they wish to check. A button for changing the reference time, such as button 1101 in FIG. 11, may be provided. When the user operates this button, the user can specify the time they wish to check for color variation, and the color variation at the specified time may be displayed on the UI display unit 215. The method for specifying the time you wish to check may include a method for specifying a relative time based on the current time, as in the setting field 1102a in FIG. 11(a), or a method for specifying a date and time, as in the setting field 1102b in FIG. 11(b). More preferably, when button 1101 is operated, the CPU 212 refers to data stored in the HDD unit 214, and it is desirable to gray out times for which no color variation information remains, preventing the user from specifying them. Furthermore, the user may be able to specify and display the name of the print job or the person who submitted the print job, thereby assisting in the acceptance of the print job and improving operability.

[0080] In this embodiment, the color is acquired from patches consisting of the same toner image on the image carrier and on the recording medium. However, this is not limited to the above example. If the main scanning positions that can be read by the density sensor 310 and the image reading unit 331 are different, the color may be acquired from different patches under the same printing conditions. Examples of acquiring the color from different patches are shown in FIGS. 12 and 13. FIG. 12 shows the same conditions as FIG. 4, and FIG. 13 shows the same conditions as FIG. 5. For example, if the density sensor 310 can measure near the center of the image carrier and the image reading unit 331 can only measure at the end of the transport path, the patches for acquiring the color may be separated, as shown by 501 and 504 in FIG. 12. Patch 501 acquires the color on the image carrier, and patch 504 acquires the color on the recording medium 503. In the above case, as shown in FIG. 13, it is preferable that patches for acquiring the color only on the image carrier not be formed on the recording medium 503.

[0081] In this embodiment, an example has been described in which the image forming apparatus 101 is provided with multiple display units (UI display units 202, 215), with print job settings being performed on the UI display unit 202 and color variation being displayed on the UI display unit 215. The combination of displayed items and display units is not limited to the above example. For example, if the only display unit available is the UI display unit 202, all items may be displayed on a single display unit.

[0082] <Second embodiment> The color acquisition process according to this embodiment will now be described. In the first embodiment, an example was described in which a patch 501 for acquiring a color was formed on a recording medium 503. However, color acquisition is not limited to the above example. For example, there may be cases in which a toner image 502 based on input image data occupies a large proportion of the recording medium 503, making it impossible to position the patch 501 on the recording medium 503. In such cases, it is desirable to acquire a color from a toner image based on the input image data and check for color variations.

[0083] Referring to FIG. 14, the processing in the image inspection unit 109 according to the second embodiment will be described. Similar to the first embodiment, FIG. 14 is a flowchart showing the processing steps for acquiring color variations during a print job executed by the printing unit 107 in the image inspection unit 109 and displaying the results. Two steps differ from the first embodiment: S1402 and S1408. In S1402, the user specifies a position on the recording medium 503 from which color variations are acquired from input image data. In S1408, information comparable to the color variations on the image carrier is estimated from the acquired color variations. The printing system and functional configuration according to this embodiment are the same as those of the first embodiment, and therefore a description thereof will be omitted. The processing in S1402 and S1408, which differs from the first embodiment, will be described. The processing in S1402 is executed by the CPU 206 of the printing unit 107, and the processing in S1408 is executed by the CPU 212 of the image inspection unit 109.

[0084] In S1402, the CPU 206 accepts an instruction for a position on the recording medium 503 from which to acquire color based on an instruction from the user on the UI display unit 202. FIG. 15 shows an example of a screen for accepting instructions from the user. When color variation detection is set on the setting screen shown in FIG. 7, the CPU 206 controls the UI display unit 202 to display the screen shown in FIG. 15. As shown in FIG. 15, a preview of the image data submitted by the user as a print job is displayed, prompting the user to specify a position from which to acquire color. The user selects a method for specifying the position from a task bar 1501. For example, the user can select a method for specifying the center position of the measurement position, such as specifying the center position with a cursor, a rectangle, or a circle. The example in FIG. 15 shows an example in which the center position of the measurement position is specified with a cursor. The user moves a cursor 1502 on the preview screen to specify the position. Upon receiving an instruction from the user, the position is notified to the user by a highlighted rectangle 1503. When the CPU 206 confirms the user's operation of the OK button, it stores the last designated position in the memory 207 as the position on the recording medium 503 where the color tone is to be measured, and proceeds to S1403.

[0085] While the present embodiment illustrates an example in which the user specifies one position, the number of positions is not limited to one. Acquiring color at multiple positions allows for stable acquisition of color variations. It is desirable to determine an upper limit based on the number of areas that can be acquired by the image reading unit 331 while the recording medium 503 is being conveyed. While the example in which the user specifies the area has been described, the method for specifying the acquisition area does not have to be user-specified. As shown by 1504 in FIG. 15 , the system may be configured so that the CPU 206 automatically selects an area based on the image data of a print job submitted by the user. It is desirable for the acquisition area to have the same printing conditions (toner combination, area ratio) as the patch 501 on the image carrier from which the color is acquired. For example, the system may be configured to automatically select an area of ​​image data with printing conditions that are the same as or similar to the printing conditions included in the patch 501.

[0086] In S1408, the image inspection unit 109 estimates the amount of toner on the recording medium 503 under the same printing conditions as the patch 501 that acquires the color on the image carrier, from the acquired RGB values. FIGS. 16 and 17 are schematic diagrams showing how the color is acquired in the second embodiment. FIG. 16 is a diagram showing the same conditions as FIG. 4, and FIG. 17 is a diagram showing the same conditions as FIG. 5. In the second embodiment, the patch 501 shown in 501 in FIG. 16 acquires the color on the image carrier. As shown in FIG. 17(b), the color on the recording medium 503 is acquired at the position specified by the user in S1402. As shown in FIG. 17, in the second embodiment, the patch that acquires the color on the image carrier is not formed on the recording medium 503.

[0087] In S1408, unlike S607, the color tone in the mixed color area consisting of multiple toners is acquired, so the toner amount is acquired using a color conversion method different from that in S607. First, the RGB values ​​are converted into the device-independent Lab color space. Then, the T that represents the device-dependent toner amount is converted from the device-independent Lab. CMYK Each color conversion is performed using a 3D LUT similar to the format explained in the first embodiment. CMYKThe conversion to this uses the same 3D LUT as the conversion used when converting input image data to a toner image. By converting to a device-independent color space once and then obtaining the toner amount using the same conversion as the input image data, it is possible to obtain the toner amount with high accuracy even from mixed color areas.

[0088] Next, the acquired toner amount T CMYK From the above, the toner amount T on the intermediate transfer belt 308 is calculated based on the engine condition. out In this embodiment, the engine state is estimated based on the input toner amount T in and the toner amount T actually recorded on the recording medium 503 out The engine status changes depending on the temperature and humidity inside the machine and the timing of toner cartridge replacement. We hold multiple assumed engine statuses and calculate the toner amount T obtained using the 3D LUT. CMYK The engine state closest to the toner amount T is searched for and determined to be the current engine state. The engine state is estimated for each toner color. k This will be explained using the following example.

[0089] First, an example of determining the engine state will be described. Fig. 18(a) is a diagram showing a plurality of engine states stored in advance. If the engine state is close to the reference state, as shown in 1801, the toner amount T in and the toner amount T on the recording medium 503 out In the engine state shown in FIG. 18(a), the input toner amount T image and T obtained with 3D LUT k The engine state that is closest to the relationship between the input toner amount and T image On the axis (1802), the value T k In the example of FIG. 18(a), T image The toner image of T = 75 was formed on the recording medium 503, but the amount of toner on the recording medium 503 acquired by the image reading unit 331 was T kThis shows a schematic example of the 1802 axis. image =75 and T k The engine state 1804 closest to the intersection with =160 is determined to be the current engine state.

[0090] Next, based on the engine status searched, the area ratio is set to 50% (toner amount T patch =128) on the recording medium 503 out An example of the estimation is shown in FIG. 18(b). patch = 128 out In the example of FIG. 18(b), T patch = 128 as the corresponding value of T out = 200. T out The estimation is performed for each toner color, and the estimated values ​​for all toner colors are stored in memory 213, and the process proceeds to S1409. The processing from S1409 onwards is the same as in the first embodiment, so a description thereof will be omitted. As in the first embodiment, the processing from S1403 to S1412 is performed on a page-by-page basis. If the print job is data made up of multiple pages, S1403 to S1412 are repeatedly executed for each page, and are repeated until printing of all pages included in the print job is completed.

[0091] As explained above, an example has been described in which the color on the recording medium 503 is acquired from the toner image corresponding to the input image data when the toner image 502 based on the image data input as a print job occupies a large proportion of the recording medium 503. The color under the same printing conditions is estimated from the input image toner image, which is under different printing conditions than the patch toner image on the intermediate transfer belt 308. By adding the above estimation means, even when the toner image 502 based on the input image data occupies a large proportion of the recording medium 503, the color variation on the intermediate transfer belt 308 and the color variation on the recording medium 503 are displayed, allowing the user to compare the variations. As a result, the user can understand in which printing process the color variation is occurring.

[0092] In the present embodiment, an example has been described in which a color tone under the same printing conditions is estimated from an input image toner image under different printing conditions from the patch toner image. However, the effects of the present invention are not limited to the above example. The printing conditions for forming the patch toner image may be changed based on the printing conditions of an area selected by the user. In the above example, when an area designation is received from the user in S1402, the CPU 206 changes the printing conditions of the patch toner image so that the printing conditions within the area match the printing conditions of the patch toner image formed in S1403, and stores the changes in the memory 207.

[0093] Furthermore, in this embodiment, an example has been described in which color variations under the same printing conditions are estimated from an input toner image under printing conditions different from those of the patch toner image, and color variations under the same conditions are displayed. However, the printing conditions that can be displayed are not limited to the above. In addition to color variations under the same conditions, it is desirable to be able to display color variations under printing conditions within an area specified by the user that are different from those of the patch toner image. In addition to comparing color variations under the same printing conditions on the intermediate transfer belt 308 and the recording medium 503, comparing color variations under different printing conditions on the recording medium makes it possible to further narrow down the causes of variation. <Other embodiments>

[0094] In the first and second embodiments, examples have been described in which the variations and differences in color are displayed side by side, but the present invention is not limited to the above examples. As shown in the schematic diagram of FIG. 19, the variations and differences in color in each printing process may be displayed in different ways and superimposed. As a more suitable display method, the presence or absence of a variation in color that exceeds the variation reference value on the latest printed page or the direction of the variation in color (density up, density down) may be displayed using icons, as in the icon 2001 on the display screen shown in FIG. 20. The displayed icons are determined by the R ITB The three values ​​of 1, -1, and 0 can be assigned to Up, Down, and no change, respectively, or R paperThe three values ​​of 1, -1, and 0 may be assigned to Up, Down, and no change, respectively. Also, in Fig. 20, the increase or decrease in color variation from the previous page to be printed may be displayed using icons. The display method is not limited to icons, and may be any other method that the user can easily check.

[0095] The present invention may be applied to a system consisting of multiple devices, such as a host computer, an interface device, a reader, and a printer, or may be applied to an apparatus consisting of a single device, such as a copier or a facsimile machine.

[0096] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions. The disclosure of this specification includes the following image forming apparatus, display method for the image forming apparatus, and program. (Item 1) a printing unit that prints on a recording medium according to an input print job; a first acquisition unit that acquires a first color on an image carrier during printing processing; a second acquisition unit that acquires a second color on the printed recording medium; a display unit that displays color variation information based on the acquired color, the display unit displays first color variation information based on the first color and second color variation information based on the second color. Image forming device. (Item 2) The color includes at least one of a toner amount, a density, a brightness, a saturation, and a hue. Item 2. The image forming apparatus according to item 1. (Item 3) The color variation information includes at least one of a difference between a reference value and the acquired toner amount, a difference between a reference value and the acquired density, a lightness difference between a reference value and the acquired lightness, a saturation difference between a reference value and the acquired saturation, a hue difference between a reference value and the acquired hue, and a color difference between a reference value and the acquired color. Item 3. The image forming apparatus according to item 1 or 2. (Item 4) Further, a determination processing unit is provided for acquiring color variation information based on the acquired color and a reference color, the determination processing unit acquires the first color variation information based on the first color on the image carrier and the second color variation information based on the second color on the recording medium; 4. The image forming apparatus according to any one of items 1 to 3. (Item 5) the determination processing unit compares the first color variation information with the second color variation information and obtains a comparison result; the display unit displays the comparison result in addition to the first color variation information and the second color variation information. 5. The image forming apparatus according to any one of items 1 to 4. (Item 6) further comprising image adjustment means for making one or more adjustments to stabilize the color of the print; the determination processing unit determines the necessity of the one or more adjustments by the image adjustment unit based on at least one of the first color variation information, the second color variation information, and a comparison result between the first color variation information and the second color variation information. 6. The image forming apparatus according to any one of items 1 to 5. (Item 7) the image adjustment unit performs at least one of maximum density correction, gradation correction, and secondary transfer voltage adjustment for each toner color; 7. The image forming apparatus according to any one of items 1 to 6. (Item 8) the first acquisition unit acquires the first color from a patch toner image included in the toner image on the image carrier, and the second acquisition unit acquires the second color from a patch printed on the recording medium; 8. The image forming apparatus according to any one of items 1 to 7. (Item 9) a temperature and humidity acquisition unit for acquiring an internal temperature or humidity of the image forming apparatus; the determination processing unit determines the necessity of one or more adjustments by the image adjustment unit based on the first color variation information and the second color variation information as well as temperature or humidity. 9. The image forming apparatus according to any one of items 1 to 8. (Item 10) 10. The image forming apparatus according to any one of items 1 to 9, wherein the display unit changes the toner color and toner density to be displayed in accordance with a user's designation or color variation information. (Item 11) Further, a storage unit for recording the color variation information is provided, the display unit acquires the color variation information recorded in the storage unit and displays the color variation information. 11. The image forming apparatus according to any one of items 1 to 10. (Item 12) the first acquisition unit and the second acquisition unit acquire color tones from different patch toner images; 12. The image forming apparatus according to any one of items 1 to 11. (Item 13) There are a plurality of the display units, The color variation information is displayed on one or more of the display units. 13. The image forming apparatus according to any one of items 1 to 12. (Item 14) acquiring a color tone from a position of an input image toner image corresponding to the image data included in the print job, in accordance with the printing conditions of the patch toner image on the image carrier; 14. The image forming apparatus according to any one of items 1 to 13. (Item 15) changing the printing conditions of the patch toner image on the image carrier in accordance with the printing conditions of the position where the color tone of the input image toner image corresponding to the image data included in the print job is acquired; 15. The image forming apparatus according to any one of items 1 to 14. (Item 16) the first acquisition unit and the second acquisition unit acquire color tones from images under different printing conditions; 16. The image forming apparatus according to any one of items 1 to 15. (Item 17) the display unit displays the first color variation information and the second color variation information in an overlapping manner. 17. The image forming apparatus according to any one of items 1 to 16. (Item 18) the display unit has a plurality of icons according to the variation of the color variation information, and displays the icons according to the variation in addition to the color variation information. 18. The image forming apparatus according to any one of items 1 to 17. (Item 19) 1. A display method for an image forming apparatus having a printing unit that prints on a recording medium in accordance with an input print job, comprising: the first acquisition unit acquires a first color on the image carrier during printing processing; a second acquisition unit that acquires a second color tone on the printed recording medium; a display unit that displays color variation information based on the acquired color, the display unit displays first color variation information based on the first color and second color variation information based on the second color; A display method for an image forming apparatus. (Item 20) 19. A program for causing a computer to function as each means of the image forming apparatus according to any one of items 1 to 18.

[0097] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0098] Image forming apparatus 101, density sensor 310, image reading unit 331, printing unit (image forming unit) 107, image inspection unit 109, patch 501 for color acquisition, recording medium 504

Claims

1. a printing unit that prints on a recording medium according to an input print job; a first acquisition unit that acquires a first color on an image carrier during a printing process; a second acquisition unit that acquires a second color on the printed recording medium; a display unit that displays color variation information based on the acquired color, the display unit displays first color variation information based on the first color and second color variation information based on the second color. Image forming device.

2. The color includes at least one of a toner amount, a density, a brightness, a saturation, and a hue. The image forming apparatus according to claim 1 .

3. the color variation information includes at least one of a difference between a reference value and the acquired toner amount, a difference between a reference value and the acquired density, a lightness difference between a reference value and the acquired lightness, a saturation difference between a reference value and the acquired saturation, a hue difference between a reference value and the acquired hue, and a color difference between a reference value and the acquired color; The image forming apparatus according to claim 1 .

4. Further, a determination processing unit is provided for acquiring color variation information based on the acquired color and a reference color, the determination processing unit acquires the first color variation information based on the first color on the image carrier and the second color variation information based on the second color on the recording medium; The image forming apparatus according to claim 1 .

5. the determination processing unit compares the first color variation information with the second color variation information and obtains a comparison result; the display unit displays the comparison result in addition to the first color variation information and the second color variation information. The image forming apparatus according to claim 4 .

6. further comprising image adjustment means for making one or more adjustments to stabilize the color of the print; the determination processing unit determines the necessity of the one or more adjustments by the image adjustment unit based on at least one of the first color variation information, the second color variation information, and a comparison result between the first color variation information and the second color variation information. The image forming apparatus according to claim 5 .

7. the image adjusting unit performs at least one of maximum density correction, gradation correction, and secondary transfer voltage adjustment for each toner color; The image forming apparatus according to claim 6 .

8. the first acquisition unit acquires the first color from a patch toner image included in the toner image on the image carrier, and the second acquisition unit acquires the second color from a patch printed on the recording medium; The image forming apparatus according to claim 1 .

9. a temperature and humidity acquisition unit for acquiring an internal temperature or humidity of the image forming apparatus; the determination processing unit determines the necessity of one or more adjustments by the image adjustment unit based on the first color variation information and the second color variation information as well as temperature or humidity. The image forming apparatus according to claim 6 .

10. the display unit changes the toner color and toner density to be displayed in accordance with a user's designation or color variation information; The image forming apparatus according to claim 1 .

11. Further, a storage unit for recording the color variation information is provided, the display unit acquires the color variation information recorded in the storage unit and displays the color variation information. The image forming apparatus according to claim 1 .

12. the first acquisition unit and the second acquisition unit acquire color tones from different patch toner images; The image forming apparatus according to claim 1 .

13. There are a plurality of the display units, The color variation information is displayed on one or more of the display units. The image forming apparatus according to claim 1 .

14. acquiring a color tone from a position of an input image toner image corresponding to the image data included in the print job, according to the printing conditions of the patch toner image on the image carrier; The image forming apparatus according to claim 1 .

15. changing the printing conditions of the patch toner image on the image carrier in accordance with the printing conditions of the position where the color tone of the input image toner image corresponding to the image data included in the print job is acquired; The image forming apparatus according to claim 1 .

16. the first acquisition unit and the second acquisition unit acquire color tones from images printed under different printing conditions; The image forming apparatus according to claim 1 .

17. the display unit displays the first color variation information and the second color variation information in an overlapping manner. The image forming apparatus according to claim 1 .

18. the display unit has a plurality of icons according to the variation of the color variation information, and displays the icons according to the variation in addition to the color variation information. The image forming apparatus according to claim 1 .

19. 1. A display method for an image forming apparatus having a printing unit that prints on a recording medium in accordance with an input print job, comprising: the first acquisition unit acquires a first color on the image carrier during the printing process; a second acquisition unit that acquires a second color tone on the printed recording medium; a display unit that displays color variation information based on the acquired color, the display unit displaying first color variation information based on the first color and second color variation information based on the second color; A display method for an image forming apparatus.

20. A program for causing a computer to function as each of the means of the image forming apparatus according to any one of claims 1 to 18.

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