Printing device, printing control method and program

Abstract

To reduce feedback delay as possible while maintaining the suppressing effect of gradation fluctuation when performing gradation correction in real-time during the processing of a print job.SOLUTION: The density reference value for gradation correction is managed in association with the paper type registered in a paper cassette of a printing apparatus. With this, feedback of parameters required for gradation correction is uninterrupted even when the print job is switched unless the paper type registered in the paper cassette is changed.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] This relates to a technology for stabilizing color tone during continuous printing. [Background technology]

[0002] When printing a large number of pages, it is necessary to suppress gradation fluctuations so that image quality does not change between pages. In this regard, one technology for performing gradation correction in real time during print job processing involves reading gradation correction patches printed on paper with a colorimetric sensor and feeding back the results to perform gradation correction on subsequent pages. While this technology, which feeds back the final print results, is expected to accurately suppress gradation fluctuations, it is known that feedback delays occur depending on the paper circulation within the print engine and the length of the transport path to the colorimetric sensor. Patent Document 1 discloses a technology for managing density reference values ​​and density correction values ​​for gradation correction on a print job-by-print job basis. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-225170 Summary of the Invention [Problem to be solved by the invention]

[0004] Depending on the host-side printing application, the data to be printed may be divided into multiple print requests, and the section where gradation variation needs to be suppressed may not necessarily be collected into a single print job. There are also use cases where a large number of print jobs with a small number of pages are processed consecutively. In these cases, the method described in Patent Document 1 resets the density reference value for suppressing gradation variation for each print job, resulting in a certain number of pages not undergoing gradation correction at the end of each print job. It is also possible to insert a page at the beginning of a print job to obtain the density reference value, but this would further extend the total print processing time.

[0005] The present invention has been made in view of the above-mentioned problems, and aims to provide a method for suppressing gradation fluctuations when performing gradation correction in real time during the processing of a print job. Across print jobs The objective is to reduce the occurrence of feedback delay as much as possible while maintaining the same level of accuracy. [Means for solving the problem]

[0006] A printing device according to the present disclosure includes a plurality of paper feed stages that store sheets, a forming unit that forms an image of a print job and a gradation pattern image on a sheet fed from any one of the plurality of paper feed stages, a colorimetric unit that reads and measures the color of the gradation pattern image formed by the forming unit, a generating unit that generates correction data based on a result of comparison between a colorimetric result by the colorimetric unit and a reference value, and a correcting unit that performs gradation correction on image data to be printed using the correction data generated by the generating unit, wherein the reference value is a density value obtained by measuring the color of the gradation pattern image on a sheet fed from a first paper feed stage that stores sheets of a first sheet type with the colorimetric unit, and is registered in association with the first sheet type, and the registered reference value is When the reference value was obtainedThe correction data is also used for print jobs other than the print job, and the generation means generates the correction data using the reference value even after the paper feed tray that feeds sheets to the forming means is switched from the first paper feed tray to a second paper feed tray that contains sheets of the first sheet type. [Effects of the Invention]

[0007] According to the technology of the present disclosure, when performing gradation correction in real time during the processing of a print job, it is possible to suppress gradation fluctuations. Across print jobs This allows the occurrence of feedback delay to be reduced while maintaining the same level of accuracy. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1A is a diagram showing an example of the configuration of a printing system, and FIG. 1B is a block diagram showing an example of the hardware configuration of a printing device. [Figure 2] A diagram illustrating the internal configuration of an electrophotographic print engine [Figure 3] FIG. 1 is a block diagram illustrating an example of the software configuration of a printing device. [Figure 4] FIG. 1 is a sequence diagram illustrating the flow of printing processing in a printing device. [Figure 5] FIG. 1 is a sequence diagram illustrating the flow of printing processing in a printing device. [Figure 6] A schematic diagram showing how patches on paper are measured [Figure 7] 1A is a diagram showing an example of measurement value data, FIG. 1B is a diagram showing an example of reference value data, and FIG. 1C is a diagram showing an example of correction values. [Figure 8] Sequence diagram showing the process flow when changing paper [Figure 9] 10A and 10B are diagrams showing examples of a paper feed cassette setting screen; [Figure 10] FIG. 10 is a diagram showing an example of a paper setting screen. [Figure 11] Flowchart showing the process of managing reference and correction values ​​together [Figure 12]Flowchart showing the process flow for individual management of reference values ​​and correction values [Figure 13] 10A to 10C are diagrams showing examples of a reference value management table; [Figure 14] 1A to 1C are diagrams showing an example of a correction value management table; DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the present invention, and not all of the combinations of features described in the embodiments are necessarily essential to the solution of the present invention.

[0010] [Embodiment 1] <System configuration> FIG. 1(a) is a diagram showing an example of the configuration of a printing system according to this embodiment. As shown in FIG. 1(a), the printing system includes a printing device 10 and a host PC (information processing device) 20 connected via a network 30 such as a LAN. The printing device 10 has a function (printing function) of forming an image on a recording medium such as paper or a plastic sheet (hereinafter referred to as "paper") in accordance with a print request received from the host PC 20. The configuration of the printing system is not limited to that shown in FIG. 1(a), and it is sufficient that at least one or more information processing devices and the printing device are connected to be able to communicate via the network 30. Furthermore, the network 30 may be wireless or wired.

[0011] <Hardware configuration of the printing device> FIG. 1(b) is a block diagram showing an example of the hardware configuration of a printing device 10 according to this embodiment. The printing device 10 has a controller 100, an operation unit 110, a print engine 200, and a colorimetric sensor 220. The printing device 10 of this embodiment will be described as a device specialized for printing (single function peripheral), but the scope of application of this embodiment is not limited to this. For example, the printing device 10 may be a device (multi-function peripheral) that has a scanner function and a fax function in addition to a printing function. Each hardware unit included in the printing device 10 will be described below.

[0012] The controller 100 includes a CPU 101 , a ROM 102 , a RAM 103 , a storage 104 , an operation unit I / F 105 , an image processing unit 106 , an engine I / F 107 , a sensor I / F 108 , and a communication I / F 109 .

[0013] The CPU 101 is an arithmetic processing unit that controls the overall operation of the printing device 10. The CPU 101 loads programs stored in the ROM 102 or storage 104 into the RAM 103 and executes them to perform various control operations, such as printing control and colorimetry control. The ROM 102 stores control programs, boot programs, and the like that can be executed by the CPU 101. The RAM 103 is the CPU 101's main memory and is used as a work area or a temporary storage area for loading various control programs. The storage 104 stores various image data, various programs, various setting information, and the like. In this embodiment, the storage 104 is assumed to be an HDD, but non-volatile memory such as an SSD may also be used. Note that in this embodiment, one CPU 101 uses one memory (RAM 103) to execute each process shown in the flowcharts described below, but this is not limiting. For example, multiple CPUs, RAMs, ROMs, and storages may work together to execute each process shown in the flowcharts described below. Furthermore, some processes may be executed using hardware circuits such as an ASIC or FPGA.

[0014] The operation unit I / F 105 is an interface connecting the operation unit 110 and the controller 100. The operation unit 110 is equipped with a display with a touch panel function, various hard keys, and the like, and functions as a display unit that displays information and a reception unit that receives user instructions. The image processing unit 106 has the functionality of a RIP (Raster Image Processor) and interprets PDL data included in a print request received from the host PC 20 via the communication I / F 109 to generate page image data for print processing. The image processing unit 106 also performs various image processing operations, such as resolution conversion and gradation correction, on the generated page image data. Note that in this embodiment, the image processing unit 106 is assumed to be implemented using a hardware circuit (such as an ASIC or FPGA), but this is not limited to this. For example, a separate processor (GPU) for image processing may be provided, and the GPU may execute an image processing program to interpret the PDL data and perform various image processing operations. In this case, the GPU and the CPU 101 cooperate to implement the flowcharts described below. Furthermore, the image processing program may be executed by the CPU 101. Image processing may also be performed using any combination of these methods.

[0015] The engine I / F 107 is an interface that connects the controller 100 and the print engine 200. The print engine 200 prints an image on paper fed from a paper feed cassette (also called a "paper feed stage") based on print image data generated by the image processing unit 106. The printing method of the print engine 200 may be an electrophotographic method or an inkjet method. Other printing methods, such as a thermal transfer method, may also be applied.

[0016] The sensor I / F 108 is an interface that connects the controller 100 and the colorimetric sensor 220. The colorimetric sensor 220 is located downstream of the paper transport path of the print engine 200, and measures the colors of gradation correction patches (hereinafter simply referred to as "patches") formed on the paper after printing, and generates colorimetric data.

[0017] The controller 100 is connected to the network 30 via a communication I / F 109. The communication I / F 109 receives a print request from a host PC on the network 30.

[0018] <Print engine details> Figure 2 is a diagram illustrating the internal configuration of an electrophotographic print engine 200 according to this embodiment. The area enclosed by a dashed line in Figure 2 indicates the print engine 200. The print engine 200 has four stations corresponding to the toners cyan (C), magenta (M), yellow (Y), and black (K). These four stations are arranged horizontally, and toner images are formed sequentially in the order of yellow, magenta, cyan, and black.

[0019] Each station is equipped with a photosensitive drum 201 as an image carrier. A charger 202, an exposure device 203, a developing device 204, a cleaning device 207, and a pre-exposure device 208 are arranged on the circumferential surface of the photosensitive drum 201. The developing device 204 is equipped with a developing roller 205 that supplies a developer (toner) to the photosensitive drum 201. In the intermediate transfer unit 206, an intermediate transfer belt 209 is connected to a primary transfer roller 210 that faces the photosensitive drum 201 at each station via the intermediate transfer belt 209. Furthermore, a secondary transfer inner roller 211 and a secondary transfer roller 212 are also connected via the intermediate transfer belt 209, and are arranged so that the intermediate transfer belt rotates in the conveyance direction. The fixing device 213 is composed of a heating film (heating rotator) 214, a fixing roller 215, and a pressure roller 216, and heats and pressurizes the toner transferred to the paper 222 to fix it. A paper discharge roller 217 discharges the paper 222 that has passed through the fixing device 213 onto a paper discharge tray 218. A colorimetric sensor 220 is installed between the fixing device 213 and the paper discharge roller 217 so as to be able to read the printed surface, measures the density of the patch formed on the paper 222 after fixing, and notifies the controller 100 of the colorimetric data (density data). A cleaning blade 221 cleans toner that remains on the intermediate transfer belt 209 without being transferred to the paper 222 during the secondary transfer. A paper feed roller 224 feeds the paper 222 stored in a paper feed cassette 223. Note that although FIG. 2 shows one paper feed cassette 223, the printing device 10 is assumed to be equipped with multiple paper feed cassettes 223 that accommodate various paper sizes and types.

[0020] <Printing device software configuration> Next, we will explain the software configuration of the printing device 10. Fig. 3 is a block diagram showing an example of the software configuration of the printing device 10 according to this embodiment. A print request from the host PC 20 is input to a print job generation unit 301 in the printing device 10. Here, the print request includes data (PDL data) describing the image to be printed in PDL (Page Description Language), as well as print setting information that specifies various printing conditions (paper size, paper type, number of pages, number of copies, etc.).

[0021] Based on the input print request, the print job generation unit 301 generates a job (print job) for executing print processing in the print engine 200. The generated print job is registered in the print job control unit 303.

[0022] The print job control unit 303 instructs the page control unit 304 to start processing all pages to be printed included in the registered print job, starting from page 1, and starts print processing (page processing) for each page. Upon receiving the instruction to start processing from the print job control unit 303, the page control unit 304 executes and controls page processing for the specified page. Then, when the print job control unit 303 receives a notification from the page control unit 304 that processing for the next page can be started, the print job control unit 303 instructs the page control unit 304 to start processing for the next page. This is repeated for all pages. Then, when the page control unit 304 notifies the print job generation unit 301 that page processing has been completed for all pages, the print job control unit 303 notifies the print job generation unit 301 that the print job has been completed.

[0023] The PDL analysis unit 302 analyzes and converts into intermediate data the PDL data included in the print request received from the host PC 20. The RIP control unit 305 then rasterizes the intermediate data and converts it into image data in bitmap format on a page-by-page basis.

[0024] The page image generation unit 306 performs gradation correction processing on the bitmap image data for each page generated by the RIP control unit 305, and generates print image data for each page. In the gradation correction processing, a correction value corresponding to the paper type used to print that page is reflected each time. In the following description, the print image for each page will be referred to as a "page image." The page image data generated by the page image generation unit 306 is sent to the engine control unit 307.

[0025] The engine control unit 307 includes a patch synthesis unit 308 , a reference value storage unit 309 , a correction value storage unit 310 , a sensor control unit 311 , a paper feed cassette management unit 312 , a paper feed control unit 313 , and a print control unit 314 .

[0026] The patch synthesis unit 308 synthesizes patches with gradually varying gradations for each color of colorant (here, each color of CMYK) with the page image received from the page image generation unit 306. Data for the page image to which patches for each color have been added by the synthesis process (hereinafter referred to as a "page image with patches") is sent to the print control unit 314. The paper feed control unit 313 controls the paper feed cassette 223 according to the paper size and paper type specified in the print job, and transports and supplies the paper stored in the paper feed cassette 223.

[0027] The print control unit 314 uses the page image data with the patch to print an image on paper supplied by the paper feed control unit 313, and then ejects the paper.

[0028] The sensor control unit 311 controls the colorimetric sensor 220 to measure the density of patches formed on printed paper and acquire colorimetric data. The reference value storage unit 309 stores density reference values ​​(hereinafter simply referred to as "reference values") for gradation correction generated based on the colorimetric data acquired by the sensor control unit 311 for each type of paper stored in the paper feed cassette 223. The correction value storage unit 310 stores density correction values ​​(hereinafter simply referred to as "correction values") for gradation correction calculated by comparing the reference values ​​stored in the reference value storage unit 309 with the colorimetric data acquired by the sensor control unit 311 for each type of paper stored in the paper feed cassette 223.

[0029] The paper feed cassette management unit 312 manages information about the paper stored in all paper feed cassettes 223 provided in the printing device 10. The paper feed cassette management unit 312 also controls the resetting of the reference values ​​stored in the reference value storage unit 309 and the correction values ​​stored in the correction value storage unit 310. In this embodiment, information about paper is managed using a table system, and management tables for the above-mentioned basic values ​​and correction values ​​are provided. Details of the management tables and the reset process for the reference values ​​and correction values ​​will be described later. The UI control unit 315 displays a specified UI screen on the operation unit 110 and requests the paper feed cassette management unit 312 to register a paper type.

[0030] <Printing process sequence> Next, the processing in the printing device 10 that receives a print request from the host PC 20 will be described. Figures 4 and 5 are sequence diagrams showing the flow of processing in the printing device 10. The series of operations shown in the sequence diagrams of Figures 4 and 5 are realized by the CPU 101 reading a program stored in ROM 102 into RAM 103 and executing it. Note that the symbol "S" in the following explanation of the sequence diagrams and flowcharts represents a step.

[0031] First, the print job generation unit 301 generates a print job based on a print request from the host PC 20, and registers the print job in the print job control unit 303 (S401). Upon receiving the print job registration, the print job control unit 303 determines the execution order of the registered print jobs and starts processing in accordance with the determined order (S402). The following steps S403 to S429 are repeated the number of times equal to the number of pages specified in the print job being processed.

[0032] The print job control unit 303 instructs the page control unit 304 to start processing the target page (page N) in the target print job (S403). In response to this instruction, the page control unit 304 queries the paper feed cassette management unit 312 as to which paper feed cassette to use to feed paper of the paper size and paper type specified for page N (S404). The paper feed cassette management unit 312 determines which paper feed cassette to use to feed paper from based on the information on the paper size and paper type specified for page N, and returns the result to the page control unit 304 (S405).

[0033] The page control unit 304 receives information about the paper feed cassette to be used from the paper feed cassette management unit 312 and instructs the paper feed control unit 313 to feed paper from the paper feed cassette identified by the information (S406). The paper feed control unit 313 feeds paper from the paper feed cassette determined by the paper feed cassette management unit 312 in accordance with the paper feed instruction from the page control unit 304 (S407) and returns the paper feed result to the page control unit 304 (S408). If the paper feed result from the paper feed control unit 313 indicates "normal," the page control unit 304 notifies the print job control unit 303 that it is now possible to start processing the next page (S409). Furthermore, upon receiving the "normal" paper feed result, the page control unit 304 instructs the page image generation unit 306 to generate and transfer a page image (S410). At this time, information about the paper feed cassette from which paper was fed, the paper size, and the paper type is also notified.

[0034] Upon receiving the instruction to generate and transfer a page image, the page image generation unit 306 requests the correction value storage unit 310 for a correction value corresponding to the paper type related to the paper feed based on the notified information (S411). The correction value storage unit 310 searches the RAM 103 to determine whether a correction value corresponding to the paper type related to the paper feed is stored therein (S412). If a matching correction value is found as a result of this search, the correction value storage unit 310 notifies the page image generation unit 306 of the found correction value (S413). In this case, the page image generation unit 306 performs gradation correction processing using the notified correction value to generate a page image (S414). On the other hand, if a matching correction value is not found as a result of the search in S412, the correction value storage unit 310 notifies the page image generation unit 306 that a matching correction value does not exist (S415). In this case, the page image generation unit 306 generates a page image without performing gradation correction processing (S416). Then, the page image generation unit 306 transfers the generated page image data of the Nth page together with information about the paper fed in S407 (hereinafter referred to as "paper feed information") to the patch synthesis unit 308 (S417). In this case, the paper feed information includes information such as the paper size and paper type of the paper, and the paper feed cassette that contains the paper.

[0035] The patch composition unit 308 composites the above-described patches for each color into the margins of the page image received from the page image generation unit 306 to generate a patched page image (S418). Next, the patch composition unit 308 transmits the generated patched page image data to the print control unit 314 along with the above-described paper feed information, and instructs the print control unit 314 to execute printing (S419). In response to this print execution instruction, the print control unit 314 prints on paper supplied by the paper feed control unit 313 in accordance with the received patched page image data (S420). When printing is complete, the print control unit 314 notifies the page control unit 304 and the sensor control unit 311 that printing is complete (paper ejection is complete) (S421). The above-described paper feed information is added to this notification of printing completion (paper ejection is complete). Upon receiving the notification that printing is complete (paper ejection is complete), the page control unit 304 notifies the print job control unit 303 that processing of the Nth page is complete (S422). Meanwhile, upon receiving the notification that printing is complete (paper ejection is complete), the sensor control unit 311 uses the colorimetric sensor 220 to measure the density of the patches formed on the paper during printing in S420 (S423). FIG. 6 is a schematic diagram illustrating how patches are measured. In the example of FIG. 6, patches for each CMYK color for real-time gradation correction are printed parallel to the conveyance direction, aligned with the positions of the two colorimetric sensors 220a and 220b, in a marginal area inside the paper 222 and outside the print guaranteed area 600. The print guaranteed area 600 is the portion that will become the final product, and is an area in which the print quality of the target image specified in the print job is guaranteed. Meanwhile, although an image can be formed in part outside the print guaranteed area 600, it is assumed that the area will not be used in the final product and will be cut or removed. Printers for so-called POD (Print on Demand) use these patches to print various patches required for image quality adjustment and information required for inspection. As shown in FIG. 6, each of the CMYK patches 610, 620, 630, and 640 consists of 10 subpatches whose density varies in 10% increments. For example, the cyan color patch 610 has a 100% density at the leftmost subpatch, and the density decreases in 10% increments thereafter, with the rightmost subpatch having a density of 10%. Similarly, magenta, yellow, and black patches each have a set of 10 subpatches, and the patch densities for each color are read by the colorimetric sensors 220a and 220b. The sensor control unit 311 associates the colorimetric results of each CMYK color thus obtained with the paper feed information described above and notifies the reference value storage unit 309 (S424). FIG. 7A shows an example of measurement data (density value data) in which patch densities are quantified into 1024 levels. As mentioned above, four types of patches for each CMKY are printed on the paper 222, and each patch contains 10 sub-patches, resulting in a total of 40 measurement values, as shown in Figure 7(a). Note that values ​​read by the colorimetric sensor 220 are offset in consideration of the characteristics of the colorimetric sensor 220, the white reference value of the paper, and the like, and are also treated as measurement values ​​(density values) here.

[0036] Upon receiving the notification of the colorimetry results, the reference value storage unit 309 searches to see if a reference value corresponding to the paper type specified by the paper feed information attached to the notification has been saved (S425). If a reference value is found, the reference value storage unit 309 calculates a correction value based on the found reference value and the notified colorimetry results, as described above (S426). The reference value storage unit 309 then notifies the correction value storage unit 310 of the calculated correction value (S427). Upon receiving this notification, the correction value storage unit 310 stores the correction value related to the notification in RAM 103, in association with the paper type specified by the paper information (S428). On the other hand, if a reference value was not found in S425, the reference value storage unit 309 stores the colorimetry results notified by the sensor control unit 312 in RAM 103 as a new reference value, in association with the paper type specified by the paper feed information (S429). In other words, when paper is replaced in a paper feed cassette, the density value obtained by measuring the patch formed on the paper for the first paper feed after the new paper is stored will be saved as a new reference value in association with the paper type.

[0037] S424 to S428 can be summarized as follows. If the colorimetry results notified from the sensor control unit 311 are for a paper type that has not yet been registered, the reference value storage unit 309 associates the measurement values ​​obtained by colorimetry with that paper type and stores them as new "reference values." On the other hand, if the colorimetry results notified from the sensor control unit 311 are for a registered paper type, a correction value is calculated from the measurement results. Specifically, the difference between the reference value associated with the registered paper type and the notified measurement value is calculated, and this difference is used as the correction value. The obtained difference may be used as the correction value directly, or a value obtained by performing certain processing, such as multiplying it by a constant or performing threshold judgment to reduce values ​​exceeding the threshold to below the threshold, may be used as the correction value. The correction value obtained in this way is passed to and stored in the correction value storage unit 310. Figures 7(b) and 7(c) show examples of reference value data and correction value data stored in table format in the reference value storage unit 309 and the correction value storage unit 310, respectively. Each table is assigned an ID (here, "TBL_S01" and "TBL_C01") for identification purposes, and can be referenced in a management table, which will be described later. In this embodiment, the value derived based on the measurement value and reference value for the preceding page is saved as the correction value for the next page, but this is not limited to this. For example, the measurement value may be saved for use in deriving the correction value for the next page, and the difference between the saved measurement value of the preceding page and the reference value may be calculated each time the next page is processed to obtain the correction value.

[0038] 4 and 5, each process from S403 to S429 is expressed as a loop, meaning that it is executed for all pages of the print job registered in the print job control unit 303. Also, the start of processing for the Nth page shown in S403 can be issued when a notification that processing for the next page can be started is received in S409. When the print job control unit 303 receives the processing completion notification for the Nth page (S422), it determines whether the Nth page is the final page of the target print job (S430). If the determination result indicates that the Nth page is the final page, the print job control unit 303 notifies the print job generation unit 301 of the end of the target print job (S431).

[0039] The above is the content of the basic operation of the processing in the printing device 10 according to this embodiment.

[0040] <Paper replacement sequence> Next, the process flow when replacing paper stored in the paper feed cassette will be described. Fig. 8 is a sequence diagram showing the process flow when replacing paper. Of the series of operations shown in the sequence diagram of Fig. 8, each operation in the printing device 10 is realized by the CPU 101 reading a program stored in the ROM 102 into the RAM 103 and executing it.

[0041] Because paper types have different characteristics, the printing device 10 must store the above-mentioned reference values ​​for each paper type in order to perform gradation correction correctly. Printing devices are generally designed to accommodate a wide variety of paper types, but the paper actually used during printing is the paper stored in the paper feed cassette. In this embodiment, the reference value storage unit 309 stores only the reference value corresponding to the paper type of paper actually stored in the paper feed cassette 223. Therefore, when the paper type of paper stored in the paper feed cassette 223 is changed, the reference value is reset. Specifically, the reference value corresponding to the paper type of the paper being removed (e.g., plain paper) is cleared, and the reference value corresponding to the paper type of the newly loaded paper (e.g., coated paper) is set. The specific operation is described below with reference to the sequence diagram in FIG. 8.

[0042] First, the user operates the main screen (not shown) of the operation unit 110 of the printing device 10 and selects the paper feed cassette setting screen, which is a UI screen for setting paper in the paper feed cassettes 223 (S801). Then, the UI control unit 315 acquires information about the paper set in all of the paper feed cassettes 223 of the printing device 10 from the paper feed cassette management unit 312 (S802). Then, the UI control unit 315 uses the information acquired in S802 to display the paper feed cassette setting screen on the operation unit 110 (S803). Figure 9(a) shows an example of the paper feed cassette setting screen.

[0043] Next, the user selects the paper feed cassette for which they want to refill or change paper from among buttons 901 to 904 corresponding to the paper feed cassettes displayed on the displayed paper feed cassette setting screen 900 (S804). FIG. 9A shows a state in which the button 901 corresponding to [Paper Feed Cassette 1] is selected, and [A4 Plain Paper 3] is displayed as information indicating the paper size and paper type registered for the selected [Paper Feed Cassette 1]. When the user presses the "Settings" button 905 in this state, the UI control unit 315 switches the UI display on the operation unit 110 from the paper feed cassette setting screen 900 to a paper setting screen 1000 as shown in FIG. 10 (S805). The user then loads the desired paper (here, paper of the paper type [Plain Paper 1]) into the paper feed cassette selected in S804 and selects the paper type of the newly loaded paper on the paper setting screen 1000 displayed on the operation unit 110 (S806). FIG. 10 shows a state in which [Plain Paper 1] has been selected. When the user presses the "OK" button 1001, the UI control unit 315 returns the UI display on the operation unit 110 from the paper setting screen 1000 to the paper cassette setting screen 900 and updates the display content. FIG. 9B shows the state of the paper cassette setting screen 900 after the update. [A4 Plain Paper 1] is displayed as information indicating the newly selected paper size and paper type for [Paper Cassette 1]. When the user confirms that the paper type has been changed and presses the "OK" button 906, the UI control unit 315 requests the paper cassette management unit 312 to register the paper cassette selected by the user in S804 and the paper type selected in S806 (S807).

[0044] The paper cassette management unit 312 checks whether the paper type specified in the registration request is 1) different from the paper type of the paper removed from the target paper cassette, and 2) whether it is registered as a paper type for use in a paper cassette other than the target paper cassette (S808). If the paper type specified in the registration request is different from the paper type of the removed paper and is not registered in any other paper cassette, the paper cassette management unit 312 clears the reference value corresponding to the paper type of the removed paper (S809). Furthermore, the paper cassette management unit 312 checks whether a correction value corresponding to the paper type of the removed paper is stored in the correction value storage unit 310, and if so, clears the correction value (S810). After completing the series of registration cancellation processes, the paper cassette management unit 312 performs registration processing for the paper type of the paper newly loaded by the user (S811). When the registration is completed, the paper feed cassette management unit 312 notifies the UI control unit 315 of the completion of the registration (S812).

[0045] <Resetting the reference value and correction value> Next, the details of the reset process (S808 to S811) of the reference values ​​and correction values ​​in the paper cassette management unit 312 in response to a change in the type of paper stored in a paper cassette will be explained for different cases. The first case is a case where the reference values ​​and correction values ​​are collectively managed for each paper type. The second case is a case where the reference values ​​and correction values ​​are individually managed for each paper cassette. Below, the reset process of the reference values ​​and correction values ​​will be explained in detail with reference to the flowcharts (FIGS. 11 and 12) corresponding to each case.

[0046] <Case 1: Centralized management> The process of collectively managing the reference values ​​and correction values ​​for a paper type when the same paper type is set in multiple paper feed cassettes will be described in detail with reference to the flowchart shown in FIG.

[0047] In S1101, a registration request for paper information about a paper feed cassette selected by the user (hereinafter referred to as the "selected paper feed cassette") is received from the UI control unit 315. This registration request includes information that can identify the selected paper feed cassette (such as a cassette ID) and information indicating the paper size and paper type of the paper that the user has set in the selected paper feed cassette. Note that if the paper type is not changed (when refilling with paper of the same paper type), the user does not normally open the paper feed cassette setting screen 900 to set the paper type, etc. In this case, a re-registration request for the same paper type is issued in response to opening or closing the paper feed cassette or pressing the paper refill confirmation button (not shown).

[0048] In the next step S1102, it is determined whether the contents of the registration request received in step S1101 involve a change in paper type. If the request does not involve a change in paper type (i.e., if the same paper type is being re-registered), this process ends. On the other hand, if the request involves a change in paper type, the process proceeds to step S1103.

[0049] In S1103, it is determined whether the same paper type as the pre-change paper type currently registered for the selected paper cassette is registered for another paper cassette. If the same paper type as the pre-change paper type is registered for another paper cassette, the process proceeds to S1105. On the other hand, if the same paper type as the pre-change paper type is not registered for another paper cassette (i.e., if the pre-change paper type will no longer be used in all paper cassettes provided in the printing device 10), the process proceeds to S1104.

[0050] In S1104, the reference value storage unit 309 and the correction value storage unit 310 are instructed to delete the reference values ​​and correction values ​​corresponding to the paper type before the change. In response to this instruction, the reference value storage unit 309 and the correction value storage unit 310 respectively delete the reference value and correction value data (see FIGS. 7(b) and 7(c) above) that have been stored in association with the paper type before the change. After the deletion process is complete, the process proceeds to S1105.

[0051] In S1105, the paper information records for the selected paper cassette are deleted from both the reference value management table and the correction value management table. FIG. 13(a) shows the state of the reference value management table (hereinafter referred to as the "reference value management table") before the target record is deleted, and FIG. 13(b) shows the state after the deletion. Each row of the reference value management table has the following fields: "Paper Type," "Target Paper Cassette," "Reference Value (1 / 2 Speed)," "Reference Value (1 / 1 Speed)," "Generated Page ID," and "Timestamp." Currently, the reference value management table shown in FIG. 13(a) has records indicating that the paper type [Plain Paper 3] is registered for both paper cassettes [CST1] and [CST2]. For example, the record for [CST1] indicates that the 30,000th page since power-on (2019 / 07 / 18 10:04:06) was printed on [Plain Paper 3], and the measurement value obtained by measuring the color of the printout was registered as the reference value. Figure 14(a) shows the state of the correction value management table (hereafter referred to as the "correction value management table") before the target record was deleted, and Figure 14(b) shows the state after deletion. Each row of the correction value management table contains the following fields: "Paper Type," "Target Paper Cassette," "Correction Value (1 / 2 Speed)," "Correction Value (1 / 1 Speed)," "Generated Page ID," and "Timestamp." The basic structure of the correction value management table and the reference value management table is the same, except that "Reference Value" is replaced with "Correction Value." For example, if [Plain Paper 3] is removed from [CST1] and replaced with another paper type (such as [Plain Paper 1]), the reference value management table and correction value management table will look like Figure 13(b) and Figure 14(b), respectively. In other words, the record for [CST1] will be deleted from both the reference value management table and the correction value management table.

[0052] In S1106, it is determined whether the registration request accepted in S1101 was made during job processing. If the result of the determination is that a job is being processed, the process proceeds to S1107, and if not, the process ends.

[0053] In S1107, it is determined whether the reference values ​​and correction values ​​corresponding to the changed paper type related to the registration request have been registered, that is, whether the same paper type has been set for other paper feed cassettes. If the result of the determination shows that the reference values ​​and correction values ​​corresponding to the changed paper type have not been registered, the process proceeds to S1108, and if they have been registered, the process proceeds to S1109.

[0054] In S1108, the output result of the print job whose processing was resumed after the paper change is measured, and based on the obtained measurement values, a new record containing information about the changed paper type for the selected paper feed cassette is added to the reference value management table and the correction value management table. At this time, reference value data corresponding to the changed paper type related to the registration request is newly generated and registered in the reference value storage unit 309 based on the print result of the print page immediately after the restart, and link processing is first performed to reference this reference value data. After that, correction value data corresponding to the changed paper type is newly generated and registered in the correction value storage unit 310 based on the print result of the subsequent page, and link processing is performed to reference this correction value data. Figures 13(c) and 14(c) show the reference value management table and correction value management table with a new record added when the paper type for [CST1] is changed from [Plain Paper 3] to [Plain Paper 1]. Meanwhile, in S1109, a record containing information about the selected paper cassette and the changed paper type is added to the reference value management table. The record added at this time is a record that has been linked so as to reference the registered reference value data and correction value data that correspond to the same paper type as the changed paper type. When the registration process in S1108 or S1109 is completed, this process ends.

[0055] <Case 2: Individual management> Next, a detailed description will be given of the process for managing the reference values ​​and correction values ​​individually for each paper feed cassette, even when the same paper type is set for multiple paper feed cassettes, with reference to the flowchart shown in Fig. 12. Note that a description of the parts that are common to the flowchart in Fig. 11 will be omitted, and the following description will focus on the differences.

[0056] In S1201, as in S1101, a request to register paper information for the selected paper feed cassette is received from the UI control unit 315. In the following S1202, as in S1102, it is determined whether the content of the registration request received in S1201 involves a change in paper type. If the request does not involve a change in paper type, this process ends. On the other hand, if the request involves a change in paper type, the process proceeds to S1203.

[0057] In S1203, similar to S1105, the paper information record for the selected paper feed cassette is deleted from both the reference value and correction value management tables. In the following S1204, similar to S1106, it is determined whether the registration request accepted in S1201 was made during job processing. If the result of the determination is that a job is being processed, the process proceeds to S1205; if not, the process ends.

[0058] In S1205, as in S1108, a new record for the selected paper cassette is added to the reference value management table based on the printing and colorimetry results of the print job after processing has been resumed, and reference value data corresponding to the changed paper type is newly registered in the reference value storage unit 309. At this time, reference value data corresponding to the changed paper type related to the registration request is newly generated and registered in the reference value storage unit 309 based on the print result of the page printed immediately after the restart, and the reference value data is directly associated. After that, correction value data corresponding to the changed paper type is newly generated and registered in the correction value storage unit 310 based on the print result of the subsequent page, and a record to which the correction value data is directly associated is generated. In other words, in this case, the reference value data and correction value data are managed as individual actual data, not as reference data, and are directly linked to each paper cassette.

[0059] As described above, according to this embodiment, as long as the paper type set in the paper feed cassette is not changed, the correction values ​​for gradation correction are fed back continuously and seamlessly between multiple print jobs. As a result, even when processing a large number of print jobs with a small number of pages in succession, gradation fluctuations can be suppressed across print jobs. Note that even in this embodiment, it is not possible to eliminate the blank period (period in which gradation correction is not performed) between reacquiring the reference value and generating the correction value when the paper type is changed, but the frequency of this occurrence can be limited to immediately after the paper type is changed.

[0060] (Other embodiments) 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.The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

Claims

1. a plurality of paper feed trays for accommodating sheets; forming means for forming an image of a print job and a gradation pattern image on a sheet fed from one of the plurality of paper feed stages; a colorimetric measuring means for reading and measuring the gradation pattern image formed by the forming means; a generating means for generating correction data based on a comparison result between the color measurement result by the color measurement means and a reference value; a correction unit that performs gradation correction on image data to be printed using the correction data generated by the generation unit; Equipped with the reference value is a density value obtained by measuring the color of the gradation pattern image on a sheet fed from a first paper feed stage containing sheets of a first sheet type by the colorimetric means, and is registered in association with the first sheet type, and the registered reference value is also used in other print jobs different from the print job when the reference value was obtained; the generating unit generates the correction data using the reference value even after a sheet feed stage that feeds sheets to the forming unit is switched from the first sheet feed stage to a second sheet feed stage that accommodates sheets of the first sheet type. A printing device characterized by:

2. If the first sheet type is registered for all of the plurality of paper feed trays, Even if the registration of one of the plurality of paper feed stages is changed to a second sheet type different from the first sheet type, if the first sheet type is registered in another paper feed stage, the first reference value stored in association with the first sheet type is not updated; For a paper feed stage whose registration has been changed to the second sheet type among the plurality of paper feed stages, a density value obtained by colorimetrically measuring the gradation pattern image formed on a sheet related to the first paper feed after a sheet of the second sheet type is accommodated in the paper feed stage is registered as a second reference value in association with the second sheet type.

2. The printing device according to claim 1.

3. the gradation pattern image is provided for each color of color material used in printing, The reference value is registered in association with each of the gradation pattern images for each color.

2. The printing device according to claim 1.

4. the gradation pattern image for each color is composed of a plurality of sub-gradation pattern images in which the density of each color is changed stepwise; the reference values ​​corresponding to the respective gradation pattern images for each color are registered in units of the plurality of sub-gradation pattern images; 4. The printing device according to claim 3.

5. the gradation pattern image is composed of a plurality of patch images, each of the plurality of patch images is formed using a color material of only one color; 2. The printing device according to claim 1.

6. 6. The printing apparatus according to claim 5, wherein the color material of only one color is any one of cyan, yellow, magenta, and black.

7. 6. The printing device according to claim 5, wherein the plurality of patch images include at least a first color patch image formed using a first color colorant, and a second color patch image formed using a second color colorant different from the first color colorant.

8. 6. The printing device according to claim 5, wherein each of the patch images formed using only one color material is made up of sub-patch images in which the color density is changed in stages.

9. when a sheet feed tray that feeds sheets to the forming unit is switched from the first sheet feed tray to a third sheet feed tray that stores sheets of a second sheet type different from the first sheet type, the reference value is updated.

2. The printing device according to claim 1.

10. 2. The printing device according to claim 1, wherein the gradation pattern image is printed in an area on the sheet that is different from an area in which an image designated in a print job is printed.

11. 2. The printing apparatus according to claim 1, wherein the correction data is generated based on a difference between the result of the color measurement and the reference value.

12. A control method for a printing device having a plurality of paper feed trays for storing sheets, comprising: a forming step of forming an image of a print job and a gradation pattern image on a sheet fed from one of the plurality of paper feed stages; a color measurement step of reading and measuring the gradation pattern image formed in the forming step; a generating step of generating correction data based on a comparison result between the color measurement result in the color measurement step and a reference value; a correcting step of performing gradation correction on image data to be printed using the correction data generated in the generating step; Including, the reference value is a density value obtained by measuring the color of the gradation pattern image on a sheet fed from a first paper feed stage containing sheets of a first sheet type, and is registered in association with the first sheet type, and the registered reference value is also used in other print jobs different from the print job when the reference value was obtained; In the generating step, the correction data is generated using the reference value even after a sheet feed tray that feeds sheets is switched from the first sheet feed tray to a second sheet feed tray that accommodates sheets of the first sheet type. A control method comprising:

13. A program for causing a computer to function as the means of the printing device according to any one of claims 1 to 11.

Images