Image forming apparatus, calibration method, and calibration program

Abstract

To suppress the frequency of calibration between jobs, allow jobs to be executed continuously, and suppress reduction in the printing productivity.SOLUTION: An image formation apparatus which executes multiple jobs for which instruction contents for forming images on a recording medium are set respectively, includes: multiple measurement units which respectively measure information about the recording medium; and a control unit which performs control so as to respectively execute calibration of the multiple measurement units. The control unit, when calibration at mutually different timings has been reserved or is to be reserved in the multiple measurement units, executes calibration of the multiple measurement units so that a calibration period in the one measurement unit overlaps with a calibration period in the measurement unit other than the one measurement unit when executing calibration of the one measurement unit of the multiple measurement units.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus, a calibration method, and a calibration program. [Background Art]

[0002] There has been known an image forming apparatus that performs image gradation correction to maintain appropriate image density when the type of paper is changed.

[0003] For example, Patent Document 1 discloses an image forming apparatus that determines the type of paper with a media sensor and displays a message prompting image adjustment when a change in paper is detected during printing. In this image forming apparatus, a reading device is caused to read a sheet of paper on which gradation patches are formed, and the image density is adjusted to be suitable for the sheet of paper. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2019-56862 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] Generally, a sensor such as a media sensor needs to be calibrated, for example, by adjusting a white reference level, before being used. For example, when a plurality of print jobs are being executed and there is a print job that requires use of the sensor, it is necessary to temporarily stop the printing operation to calibrate the sensor. Calibration requires a series of operations, and it takes time before the start of the next print job, resulting in a decrease in print productivity.

[0006] An object of the present invention is to provide an image forming apparatus, a calibration method, and a calibration program that can suppress the frequency of calibration between jobs, enable continuous execution of jobs, and suppress a decrease in print productivity. [Means for Solving the Problem]

[0007] The image forming apparatus according to the present invention is In an image forming apparatus that executes multiple jobs, each with its own set of instructions for forming an image on a recording medium, A plurality of measuring units that measure information related to the recording medium, A control unit that controls the calibration of each of the aforementioned multiple measuring units, Equipped with, The control unit, Regarding the calibration of the plurality of measuring units, the timing for performing the calibration that has already been reserved or will be newly reserved by the control unit is In the above-mentioned plurality of measuring units, different place In addition, when performing calibration of one of the multiple measuring units, From the start to the end of proofreading Calibration period and measurement in measurement units other than the one measurement unit in question From the start to the end of proofreading The calibration period and At least in part The multiple measurement units are calibrated to ensure overlap.

[0008] The calibration method according to the present invention is When executing multiple jobs, each with instructions for forming an image on a recording medium, calibration is performed on multiple measurement units that measure information related to the recording medium. In an image forming apparatus A calibration method, In the image forming apparatus, the timing for performing the calibration of the plurality of measuring units is such that the calibration has already been reserved or is newly reserved by the image forming apparatus. In the above-mentioned plurality of measuring units, different place In addition, when performing calibration of one of the multiple measuring units, From the start to the end of proofreading Calibration period and measurement in measurement units other than the one measurement unit in question From the start to the end of proofreading The calibration period and At least in part The multiple measurement units are calibrated to ensure overlap.

[0009] The calibration program according to the present invention is A calibration program that performs calibration of multiple measuring units that measure information about the recording medium, when executing multiple jobs, each of which has set instructions for forming an image on the recording medium, On the computer, A process for reserving the calibration for the plurality of measuring units, The timing of the calibration that is already reserved or newly reserved by the reservation process is In the plurality of measurement units, different from each other place When, when performing calibration of one measurement unit among the plurality of measurement units, in said one measurement unit From the start to the end of proofreading a calibration period and a calibration period in a measurement unit other than said one measurement unit From the start to the end of proofreading are At least in part a process of performing calibration of the plurality of measurement units such that they overlap and, is caused to be executed.

Effect of the Invention

[0010] According to the present invention, it is possible to suppress the frequency of calibration between jobs, enable continuous execution of jobs, and suppress a decrease in print productivity.

Brief Description of Drawings

[0011] [Figure 1] It is a diagram schematically illustrating an example of the overall configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 2] It is a block diagram illustrating an example of a main part of a control system of the image forming apparatus illustrated in FIG. 1. [Figure 3] It is a diagram illustrating an example of a reserved job list in the image forming apparatus illustrated in FIG. 1. [Figure 4] It is a diagram illustrating an example of adjustment mode settings in the image forming apparatus illustrated in FIG. 1. [Figure 5] It is a flowchart for explaining an example of a print processing method in the image forming apparatus illustrated in FIG. 1. [Figure 6] It is a flowchart for explaining a subroutine for determining whether pre-print calibration is necessary in the flowchart illustrated in FIG. 5. [Figure 7] It is a flowchart for explaining a subroutine for performing calibration processing in the flowchart illustrated in FIG. 5. [Figure 8] It is a flowchart for explaining a subroutine for determining a calibration valid period in the flowchart illustrated in FIG. 5. [Figure 9]Figure 5 is a flowchart illustrating the subroutine that performs the process of adding a new job. [Modes for carrying out the invention]

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0013] [Image forming apparatus] Figure 1 is a schematic diagram showing an example of the overall configuration of the image forming apparatus 1 according to this embodiment. Figure 2 is a block diagram showing an example of the main parts of the control system of the image forming apparatus 1.

[0014] The image forming apparatus 1 forms (prints) an image on a sheet of paper (recording medium) such as a single-fed sheet. As shown in Figure 1, the image forming apparatus 1 includes the main body 100, a paper feeding unit 300, an upstream reading unit 400, a downstream reading unit 500, a paper discharge unit 600, and the like.

[0015] The image forming apparatus body 100 is a color image forming apparatus that uses an intermediate transfer method utilizing electrophotographic process technology. Specifically, the image forming apparatus body 100 performs printing by first transferring the toner images of each CMYK color formed on the photoreceptor to an intermediate transfer body, superimposing the four toner images on the intermediate transfer body, and then performing a secondary transfer to paper. CMYK refers to C (cyan), M (magenta), Y (yellow), and K (black).

[0016] The image forming apparatus main unit 100 employs a tandem system in which photoreceptors corresponding to the four CMYK colors are arranged in series in the direction of travel of the intermediate transfer body, and the toner images of each color are sequentially transferred to the intermediate transfer body in a single procedure.

[0017] As shown in Figure 2, the image forming apparatus 1 comprises an image processing unit 10, an image forming unit 20, a fixing unit 30, a paper transport unit 40, a communication unit 71, a storage unit 72, a control unit 200, a paper feeding unit 300, an upstream reading unit 400, a downstream reading unit 500, and a paper discharge unit 600. The image forming apparatus 1 also includes a correction unit 700 and a calibration control unit 800.

[0018] The control unit 200 includes a CPU (Central Processing Unit) 201, a ROM (Read Only Memory) 202, and a RAM (Random Access Memory) 203, etc. The CPU 201 reads a program corresponding to the processing content from the ROM 202, loads it into the RAM 203, and works in cooperation with the loaded program to centrally control the operation of each block of the image forming apparatus 1. At this time, various data such as LUTs (Look Up Tables) stored in the storage unit 72 are referenced. The storage unit 72 is composed of, for example, a non-volatile semiconductor memory (so-called flash memory) or a hard disk drive.

[0019] The control unit 200 transmits and receives various types of data to and from external devices (e.g., personal computers) connected to a communication network such as a LAN (Local Area Network) or WAN (Wide Area Network) via the communication unit 71. For example, the control unit 200 receives image data transmitted from an external device and prints on paper based on this image data (input image data). The communication unit 71 is composed of, for example, a communication control card such as a LAN card.

[0020] The control unit 200 is connected to an operation display unit (not shown), an image processing unit 10, an image forming unit 20, a fixing unit 30, a paper transport unit 40, a communication unit 71, a storage unit 72, a paper feeding unit 300, an upstream reading unit 400, a downstream reading unit 500, and a paper discharge unit 600. The control unit 200 is also connected to a correction unit 700 and a calibration control unit 800. These units perform predetermined processing based on instructions from the control unit 200.

[0021] The operation and display unit consists of, for example, a liquid crystal display (LCD) with a touch panel, and functions as both a display unit and an operation unit. The display unit displays various operation screens, image status displays, and the operating status of each function in accordance with display control signals input from the control unit 200. The operation unit is equipped with various operation keys such as a numeric keypad and a start key, and accepts various input operations from the user and outputs operation signals to the control unit 200.

[0022] The image processing unit 10 includes circuits and other components that perform image processing on the input image data according to initial settings or user settings. The image forming unit 20 is controlled based on the image data that has undergone image processing.

[0023] The image forming unit 20 includes an image forming unit 21, an intermediate transfer unit 22, a secondary transfer unit 23, and the like. Based on the image data from the image processing unit 10, the image forming unit 21 prints each color component using colored toner.

[0024] The image forming unit 21 includes an exposure device, a developing device, a photoreceptor drum, a charging device, a drum cleaning device, etc., for each color. Since known technologies can be used for the exposure device, developing device, photoreceptor drum, charging device, and drum cleaning device, a detailed explanation is omitted here.

[0025] The intermediate transfer unit 22 includes an intermediate transfer belt, etc. The intermediate transfer belt is stretched in a loop shape across multiple support rollers and travels in the direction of arrow A. The support rollers include backup rollers, primary transfer rollers, drive rollers, etc., but these are not shown in the illustration here. The intermediate transfer belt is pressed against the photoreceptor drum, thereby transferring the toner image from the photoreceptor drum to the intermediate transfer belt.

[0026] The intermediate transfer unit 22 may also be configured to include a belt cleaning device having a plate-shaped belt cleaning blade or the like that slides against the surface of the intermediate transfer belt. The belt cleaning device removes any remaining transfer toner or the like that from the surface of the intermediate transfer belt after secondary transfer.

[0027] The secondary transfer unit 23 includes a secondary transfer roller and the like. The secondary transfer roller is pressed against the intermediate transfer belt. This creates a secondary transfer nip between the intermediate transfer belt and the secondary transfer roller.

[0028] In the secondary transfer unit 23, when paper is transported to the secondary transfer nip, the toner images of each color carried on the intermediate transfer belt are transferred onto the paper all at once. The paper on which the toner images have been transferred is then transported toward the fixing unit 30 by the secondary transfer roller.

[0029] Furthermore, the secondary transfer unit 23 may be a belt-type secondary transfer unit having a secondary transfer belt stretched across multiple support rollers, instead of a roller-type secondary transfer unit having a secondary transfer roller or the like.

[0030] The fixing unit 30 includes a fixing roller, a pressure roller, and the like. The fixing roller is heated to a predetermined fixing temperature, and the pressure roller forms a fixing nip that grips and transports the paper between itself and the fixing roller. In this fixing unit 30, the toner image is fixed to the paper by heating and pressurizing the paper that has been transported after secondary transfer of the toner image using the fixing nip.

[0031] The paper transport unit 40 consists of, for example, a path for transporting paper, multiple transport rollers, and a drive motor that rotates these transport rollers. Although not shown in the diagram, the paper transport unit 40 also has a reversing unit that transports the paper transported from the fixing unit 30 upside down to the upstream side of the secondary transfer unit 23.

[0032] The paper transport unit 40 transports the paper supplied from the paper feed unit 300 and the upstream reading unit 400 to the secondary transfer unit 23 and the fixing unit 30, and then to the downstream reading unit 500 and the paper discharge unit 600. When printing on both sides of the paper, the paper transport unit 40 uses the reversing unit, as described above, to reverse the front and back sides of the paper transported from the fixing unit 30 and transport it to the upstream side of the secondary transfer unit 23.

[0033] The paper feeding unit 300 is located upstream of the image forming apparatus body 100 in the paper transport direction D and is connected to the image forming apparatus body 100 via an upstream reading unit 400, which will be described later. The paper feeding unit 300 has a plurality of paper feeding trays 301 to 303, and each paper feeding tray 301 to 303 contains sheets of paper (standard paper, special paper) identified based on basis weight, size, etc., according to a preset type. The paper feeding unit 300 supplies the instructed paper to the image forming apparatus body 100 based on instructions from the image forming apparatus body 100.

[0034] The upstream reading unit 400 is positioned between the paper feeding unit 300 and the image forming apparatus main body 100. In the paper transport direction D, it is connected to the paper feeding unit 300 on the upstream side and to the image forming apparatus main body 100 on the downstream side.

[0035] The upstream reading unit 400 includes a sensor 410 for reading paper transported from the paper feeding unit 300, a calibration unit 420 used for calibrating the sensor 410, and the like.

[0036] The sensor 410 (the first measuring unit in this invention) is positioned above the path through which the paper is transported, facing the side of the transported paper, and is configured to read the surface (top) side of the transported paper.

[0037] Sensor 410 acquires information about the paper. This information includes, for example, the paper size (paper width, paper length, etc.) and paper position. Based on the information acquired by sensor 410, image formation conditions for printing on the paper are set. As the sensor 410 that acquires such information, an inline sensor or area sensor having a CCD (Charge Coupled Device), CIS (Contact Image Sensor), or spectrophotometer can be used.

[0038] The calibration unit 420, although not shown in the figure, includes a white reference plate, a light source, etc., for calibrating the white reference level of the paper reading sensor 410.

[0039] Furthermore, the sensor 410 may be configured to acquire information about the paper other than its size and position. For example, the sensor 410 may acquire information about the paper's smoothness, stiffness, thickness, etc. Also, the upstream reading unit 400 may be configured to read both sides of the paper using the sensor 410.

[0040] The downstream reading unit 500 is positioned between the image forming apparatus body 100 and the paper discharge unit 600. In the paper transport direction D, it is connected to the image forming apparatus body 100 on the upstream side and to the paper discharge unit 600 on the downstream side.

[0041] The downstream reading unit 500 includes a sensor 510 for reading paper transported from the image forming apparatus main body 100, a calibration unit 520 used for calibrating the sensor 510, and the like.

[0042] The sensor 510 (the second measuring unit in this invention) is positioned above the path through which the paper is transported, facing the side of the transported paper, and is configured to read the surface (top) side of the transported paper.

[0043] Sensor 510 also acquires information about the paper. As information about the paper, sensor 510 acquires, for example, image data (data related to image density, color shift, etc.) of the image printed by the image forming apparatus main unit 100. Based on the information acquired by sensor 510, image forming conditions are set. Similar to sensor 410, an inline sensor or area sensor having a CCD, CIS, spectrophotometer, etc. can be used as the sensor 510 that acquires such information.

[0044] The calibration unit 520, although not shown in the figure, includes a white reference plate, a light source, etc., for calibrating the white reference level of the paper reading sensor 510.

[0045] Furthermore, the sensor 510 may be configured to acquire information other than image density, color shift, etc., but also other information about the paper. For example, the sensor 510 may acquire the position of the printed image. Also, the downstream reading unit 500 may be configured to read both sides of the paper with the sensor 510.

[0046] The paper output unit 600 is located downstream of the image forming apparatus body 100 in the paper transport direction D and is connected to the image forming apparatus body 100 via the downstream reading unit 500. The paper output unit 600 outputs the paper transported from the image forming apparatus body 100 to the paper output tray 601.

[0047] The correction unit 700, like the control unit 200, includes a CPU, ROM, RAM, etc. The correction unit 700 uses the upstream reading unit 400 to read the paper before printing and calculates a position correction value to be used in the image forming unit 20 based on the read image data (measurement results in this invention). The correction unit 700 also uses the downstream reading unit 500 to read the paper after printing and calculates an image correction value to be used in the image forming unit 20 based on the read image data (measurement results in this invention).

[0048] The calibration control unit 800, like the control unit 200, is equipped with a CPU, ROM, RAM, etc. The calibration control unit 800 controls the sensor 410 and the calibration unit 420, and the sensor 410 reads the white reference plate of the calibration unit 420, and the white reference level of the sensor 410 is calibrated based on the read image data. The calibration control unit 800 also controls the sensor 510 and the calibration unit 520, and the sensor 510 reads the white reference plate of the calibration unit 520, and the white reference level of the sensor 510 is calibrated based on the read image data. Such calibration is performed before the use of sensors 410 and 510 in the job described later.

[0049] The image forming apparatus 1 having the above configuration executes a job for which job settings have been set for printing on paper. As a result, the image forming apparatus 1 feeds the paper with the job settings from the paper feeding unit 300 to the image forming apparatus body 100, prints the job settings on the paper in the image forming apparatus body 100, and then discharges the paper to the paper output unit 600. The above job settings are the instructions given for printing on the paper, and correspond to the instructions in this invention.

[0050] Incidentally, when multiple jobs as described above were running, if there was a job that used sensors 410 and 510, conventionally, the printing operation was temporarily stopped for calibration of sensors 410 and 510. Calibration required a series of operations, and since it took time before the next print job could start, it led to a decrease in printing productivity.

[0051] Therefore, in this embodiment, the image forming apparatus 1 includes a control unit 200 that controls the calibration of the upstream reading unit 400 and the downstream reading unit 500, respectively. When calibrations for the upstream reading unit 400 and the downstream reading unit 500 are scheduled or will be scheduled at different timings, the control unit 200 performs calibration of the upstream reading unit 400 and the downstream reading unit 500 simultaneously when performing one of the calibrations. Specifically, the control unit 200 performs calibration of the upstream reading unit 400 and the downstream reading unit 500 simultaneously so that the calibration period for the upstream reading unit 400 and the calibration period for the downstream reading unit 500 overlap.

[0052] In this way, by making the calibration period in the upstream reading unit 400 and the calibration period in the downstream reading unit 500 overlap, the frequency of calibration between jobs can be reduced, enabling continuous execution of jobs and suppressing a decrease in printing productivity.

[0053] Here, we will explain the jobs with reference to Figures 3 and 4. Figure 3 is a diagram showing an example of a reserved job list in the image forming apparatus 1. Figure 4 is a diagram showing an example of the adjustment mode settings in the image forming apparatus 1.

[0054] In the image forming apparatus 1, the user sets job settings for printing on paper using the operation display unit. For example, as shown in Figure 3, for each job, the user sets job settings such as the number of copies, paper size, and number of pages, as well as whether to print on one side or two sides, whether the position correction mode is enabled, and whether the image correction mode is enabled. The position correction mode corresponds to the first correction mode in the present invention, and the image correction mode corresponds to the second correction mode in the present invention.

[0055] Furthermore, when multiple jobs are scheduled to be executed consecutively, a reserved job list is created, as shown in Figure 3, listing the multiple jobs. In Figure 3, it is assumed that five jobs with IDs 1 to 5 are reserved. Such a reserved job list is stored, for example, in the memory unit 72 (see Figure 2).

[0056] The control unit 200 refers to the reserved job list shown in Figure 3, reads each job sequentially, and executes each job sequentially, thereby executing jobs continuously. At this time, the control unit 200 reads the job settings for each job and executes each job based on the job settings.

[0057] Furthermore, in each job, if the position correction mode is enabled, as shown in Figure 4, the upstream reading unit 400 is used and the downstream reading unit 500 is not used, so the upstream reading unit 400 is calibrated.

[0058] Similarly, in each job, if the image correction mode is enabled, as shown in Figure 4, the upstream reading unit 400 is not used, but the downstream reading unit 500 is used, so calibration of the downstream reading unit 500 is performed.

[0059] Next, a printing process method including a calibration method according to this embodiment, which can suppress a decrease in printing productivity, will be described with reference to Figures 5 to 9. In this embodiment, a program for executing the printing process method including the calibration method described below is stored in the ROM 202 of the control unit 200, the ROM of the calibration control unit 800, etc.

[0060] [Printing method] Figure 5 is a flowchart illustrating an example of a printing process in the image forming apparatus 1.

[0061] (Step S1010) The control unit 200 controls the proofreading control unit 800 to determine whether or not pre-print proofreading is necessary. The determination of whether or not pre-print proofreading is necessary will be described later with reference to Figure 6. The control unit 200 and the proofreading control unit 800 correspond to the control units in this invention.

[0062] (Step S1020) The control unit 200 controls the calibration control unit 800 to perform calibration processing on the upstream reading unit 400 and the downstream reading unit 500. The implementation of the calibration processing will be described later with reference to Figure 7.

[0063] (Step S1030) The control unit 200 performs the printing of the job. Specifically, the control unit 200 obtains information (job settings) for the first job from the reserved job list (see Figure 3). Then, the control unit 200 transmits the job settings and the image to be printed for the obtained job to the image forming unit 20, controls the image forming unit 20, and performs printing on the supplied paper based on the job settings.

[0064] For example, the job settings for the first job (job ID 1) from the reserved job list shown in Figure 3 are obtained. For job ID 1, the job settings are 15 copies, A4 paper size, 140 pages, and double-sided printing. Therefore, the control unit 200 transmits the job settings and the corresponding image to the image forming unit 20. The control unit 200 controls the paper feed unit 300 to sequentially feed A4 size paper with 140 pages and 15 copies to the image forming apparatus main unit 100, and controls the image forming unit 20 to print the corresponding image on both sides of the sequentially fed paper.

[0065] When the position correction mode is enabled, the control unit 200 controls the correction unit 700 to perform position correction. Specifically, the correction unit 700 uses the upstream reading unit 400 to read the paper before printing, calculates a position correction value (first correction value in this invention) to be used by the image forming unit 20 based on the read image data, and transmits it to the image forming unit 20. The image forming unit 20 uses the transmitted position correction value to print the corresponding image on both sides of the paper.

[0066] Furthermore, if the image correction mode is enabled at this time, the control unit 200 controls the correction unit 700 to perform image correction. Specifically, the correction unit 700 uses the downstream reading unit 500 to read the printed paper, calculates an image correction value (second correction value in this invention) to be used by the image forming unit 20 based on the read image data, and transmits it to the image forming unit 20. The image forming unit 20 uses the transmitted image correction value to print the corresponding image on both sides of the paper.

[0067] When performing such position correction or image correction, the upstream reading unit 400 and downstream reading unit 500 used for these corrections are calibrated in step S1020, that is, before the job is executed. This will also be described later with reference to Figure 7.

[0068] (Step S1040) The control unit 200 controls the calibration control unit 800 to determine the calibration validity period of the upstream reading unit 400 and the downstream reading unit 500. The determination of the calibration validity period will be described later with reference to Figure 8.

[0069] (Step S1050) The control unit 200 determines whether there is a request for an additional new job. For example, the control unit 200 displays a "Add New Job" button on the operation display unit, and when this button is pressed, it determines that there is a request for an additional new job. If there is a request for an additional new job (YES), the control unit 200 proceeds to step S1060; if there is no request for an additional new job (NO), it proceeds to step S1070.

[0070] (Step S1060) The control unit 200 performs the process of adding a new job. Specifically, the control unit 200 performs the process of adding a new job to the reserved job list and transmits information about the new job, including the job settings, to the calibration control unit 800. The process of adding a new job controlled by the control unit 200 and performed by the calibration control unit 800 will be described later with reference to Figure 9.

[0071] (Step S1070) The control unit 200 determines whether there are subsequent jobs. For example, the control unit 200 refers to the reserved job list shown in Figure 3 to determine whether there are subsequent jobs. If there are subsequent jobs (YES), the control unit 200 returns to step S1020; if there are no subsequent jobs (NO), it proceeds to step S1080.

[0072] (Step S1080) The control unit 200 terminates printing. That is, the control unit 200 instructs the image forming apparatus main body 100, paper feeding unit 300, upstream reading unit 400, downstream reading unit 500, paper discharge unit 600, etc., to stop printing.

[0073] Following the procedure described above, the image forming apparatus 1 executes multiple jobs and prints on paper. In this embodiment, however, before printing, it first determines whether or not pre-print proofing is necessary.

[0074] [Method for determining whether pre-print proofing is necessary] The determination of whether or not pre-print proofing is necessary will be explained below with reference to Figure 6. Figure 6 is a flowchart that explains the subroutine in step S1010, which determines whether or not pre-print proofing is necessary, in the flowchart shown in Figure 5.

[0075] (Step S2010) The calibration control unit 800 acquires the reserved job list. For example, the control unit 200 acquires the reserved job list shown in Figure 3 from the storage unit 72 and transmits it to the calibration control unit 800, thereby acquiring the reserved job list.

[0076] (Step S2020) The calibration control unit 800 acquires the job settings for jobs in the reserved job list. For example, for a job in the reserved job list shown in Figure 3, the calibration control unit 800 acquires the number of copies, paper size, number of pages, as well as job settings such as whether it is single-sided or double-sided printing, whether position correction mode is enabled, and whether image correction mode is enabled.

[0077] (Step S2030) The calibration control unit 800 refers to the acquired job settings and determines whether the job uses the upstream reading unit 400. Specifically, the calibration control unit 800 determines whether the position correction mode using the upstream reading unit 400 is enabled in the job settings. If the job uses the upstream reading unit 400 (YES), the calibration control unit 800 proceeds to step S2040; otherwise, it proceeds to step S2050.

[0078] (Step S2040) The calibration control unit 800 reserves the calibration of the upstream reading unit 400. For example, the calibration control unit 800 reserves the calibration of the upstream reading unit 400 in a data table. The data table is stored, for example, in the RAM of the calibration control unit 800, and the calibration is reserved based on flags in the data table.

[0079] (Step S2050) The calibration control unit 800 refers to the acquired job settings and determines whether the job uses the downstream reading unit 500. Specifically, the calibration control unit 800 determines whether the image correction mode that uses the downstream reading unit 500 is enabled in the job settings. If the job uses the downstream reading unit 500 (YES), the calibration control unit 800 proceeds to step S2060; if the job does not use the downstream reading unit 500 (NO), it proceeds to step S2070.

[0080] (Step S2060) The calibration control unit 800 reserves the calibration of the downstream reading unit 500. For example, the calibration control unit 800 reserves the calibration of the downstream reading unit 500 in the data table.

[0081] (Step S2070) The calibration control unit 800 determines whether there are subsequent jobs. For example, the calibration control unit 800 refers to the reserved job list shown in Figure 3 to determine whether there are subsequent jobs. If there are subsequent jobs (YES), the calibration control unit 800 returns to step S2020; if there are no subsequent jobs (NO), it proceeds to step S1020 shown in Figure 5.

[0082] Here, we will explain the method for determining whether or not pre-print proofing is necessary, referring to the reserved job list shown in Figure 3.

[0083] Referring to the reserved job list shown in Figure 3, the position correction mode is enabled for jobs with IDs 1, 2, and 5. Also, the image correction mode is enabled for jobs with IDs 2, 3, and 5. Therefore, the calibration control unit 800 reserves calibration of the upstream reading unit 400 and the downstream reading unit 500 in the method for determining whether or not pre-print proofing is necessary, as described above.

[0084] On the other hand, if the reserved job list contains jobs with the position correction mode enabled but no jobs with the image correction mode enabled, the calibration control unit 800 will reserve calibration of the upstream reading unit 400 in the method for determining whether pre-print calibration is necessary, as described above. Also, if the reserved job list contains jobs with the position correction mode enabled but there are jobs with the image correction mode enabled, the calibration control unit 800 will reserve calibration of the downstream reading unit 500 in the method for determining whether pre-print calibration is necessary, as described above.

[0085] Once the determination of whether or not pre-print proofing is necessary, as described above, the proofing process is then performed before printing.

[0086] [Calibration Processing Method] The calibration process will be explained below with reference to Figure 7. Figure 7 is a flowchart illustrating the subroutine in step S1020, where the calibration process is performed, in the flowchart shown in Figure 5.

[0087] (Step S3010) The calibration control unit 800 checks whether there is a calibration reservation for the upstream reading unit 400. If there is a calibration reservation for the upstream reading unit 400 (YES), the calibration control unit 800 proceeds to step S3020; if there is no calibration reservation for the upstream reading unit 400 (NO), it proceeds to step S3050.

[0088] (Step S3020) The calibration control unit 800 checks whether there is a calibration reservation for the downstream reading unit 500. If there is a calibration reservation for the downstream reading unit 500 (YES), the calibration control unit 800 proceeds to step S3030; if there is no calibration reservation for the downstream reading unit 500 (NO), it proceeds to step S3040.

[0089] (Step S3030) The calibration control unit 800 simultaneously performs calibration of the upstream reading unit 400 and the downstream reading unit 500. Specifically, the calibration control unit 800 instructs the sensor 410 and calibration unit 420 of the upstream reading unit 400 to perform calibration, and instructs the sensor 510 and calibration unit 520 of the downstream reading unit 500 to perform calibration.

[0090] At this time, the calibration control unit 800 performs calibration of the upstream reading unit 400 and the downstream reading unit 500, respectively, so that the calibration period of the upstream reading unit 400 and the calibration period of the downstream reading unit 500 overlap. In this case, it is desirable to overlap the calibration periods so that the calibration period of one starts and ends within the calibration period of the other, but it is also acceptable to overlap only a portion of the calibration periods.

[0091] After the upstream reading unit 400 and the downstream reading unit 500 are calibrated, the calibration control unit 800 sets the calibration status of the upstream reading unit 400 and the downstream reading unit 500 to "calibrated". The calibration control unit 800 also sets a calibration validity period A, which is the validity period of the calibration of the upstream reading unit 400, and a calibration validity period B, which is the validity period of the calibration of the downstream reading unit 500. Calibration validity period A corresponds to the first validity period in this invention, and calibration validity period B corresponds to the second validity period in this invention. The calibration status of the upstream reading unit 400 and the downstream reading unit 500, as well as calibration validity periods A and B, are set, for example, in the data table of the calibration control unit 800. Then, the process proceeds to step S1030 shown in Figure 5.

[0092] (Step S3040) The calibration control unit 800 performs calibration of the upstream reading unit 400. Specifically, the calibration control unit 800 instructs the sensor 410 and calibration unit 420 of the upstream reading unit 400 to perform calibration. After calibration of the upstream reading unit 400, the calibration control unit 800 sets the calibration status of the upstream reading unit 400 to "calibrated," sets the calibration validity period A, and then proceeds to step S1030 shown in Figure 5.

[0093] (Step S3050) The calibration control unit 800 checks whether there is a calibration reservation for the downstream reading unit 500. If there is a calibration reservation for the downstream reading unit 500 (YES), the calibration control unit 800 proceeds to step S3060. If there is no calibration reservation for the downstream reading unit 500 (NO), the calibration control unit 800 proceeds to step S1030 shown in Figure 5.

[0094] (Step S3060) The calibration control unit 800 performs calibration of the downstream reading unit 500. Specifically, the calibration control unit 800 instructs the sensor 510 and calibration unit 520 of the downstream reading unit 500 to perform calibration. After calibration of the downstream reading unit 500, the calibration control unit 800 sets the calibration status of the downstream reading unit 500 to "calibrated," sets the calibration validity period B, and then proceeds to step S1030 shown in Figure 5.

[0095] Here, the calibration process described above will be explained with reference to the reserved job list shown in Figure 3.

[0096] As described above, calibration of the upstream reading unit 400 and the downstream reading unit 500 is reserved for the reserved job list shown in Figure 3. Therefore, the calibration control unit 800 will perform calibration of the upstream reading unit 400 and the downstream reading unit 500 simultaneously in the calibration processing method described above.

[0097] In this case, as described above, calibration of the upstream reading unit 400 and the downstream reading unit 500 will be carried out so that the calibration period for the upstream reading unit 400 and the calibration period for the downstream reading unit 500 overlap. Therefore, the calibration period can be shortened compared to when the calibration of the upstream reading unit 400 and the downstream reading unit 500 is carried out at different times. In addition, since the job will be printed after the calibration of the upstream reading unit 400 and the downstream reading unit 500 is completed, the frequency of calibration between jobs can be reduced, enabling continuous execution of jobs and suppressing a decrease in printing productivity.

[0098] On the other hand, if there is a job with the position correction mode enabled and no job with the image correction mode enabled in the reserved job list, the calibration control unit 800 reserves calibration of the upstream reading unit 400 as described above. Therefore, the calibration control unit 800 performs calibration of the upstream reading unit 400 in the calibration processing method described above.

[0099] Furthermore, if there are no jobs with position correction mode enabled and there are jobs with image correction mode enabled in the reserved job list, the calibration control unit 800 reserves calibration of the downstream reading unit 500 as described above. Therefore, the calibration control unit 800 performs calibration of the downstream reading unit 500 in the calibration processing method described above.

[0100] Once the job has finished printing, the next step is to determine the proofing validity period.

[0101] [Method for determining the validity period of calibration] The determination of the calibration validity period will be explained below with reference to Figure 8. Figure 8 is a flowchart that explains the subroutine in step S1040, which determines the calibration validity period, in the flowchart shown in Figure 5.

[0102] (Step S4010) The calibration control unit 800 checks whether the upstream reading unit 400 will be used in the next job. If the upstream reading unit 400 will be used in the next job (YES), the calibration control unit 800 proceeds to step S4020; if the upstream reading unit 400 will not be used in the next job (NO), it proceeds to step S4110. Since the upstream reading unit 400 will not be used in the next job, the calibration control unit 800 proceeds to step S4110.

[0103] (Step S4020) The calibration control unit 800 checks whether the calibration validity period A has elapsed since the last calibration of the upstream reading unit 400. If the calibration validity period A of the upstream reading unit 400 has elapsed (YES), the calibration control unit 800 proceeds to step S4030; if the calibration validity period A of the upstream reading unit 400 has not elapsed (NO), it proceeds to step S4110.

[0104] (Step S4030) The calibration control unit 800 checks whether the downstream reading unit 500 will be used in the next job. If the calibration control unit 800 will use the downstream reading unit 500 in the next job (YES), it proceeds to step S4040; if it will not use the downstream reading unit 500 in the next job (NO), it proceeds to step S4050.

[0105] (Step S4040) The calibration control unit 800 checks whether the calibration validity period B of the downstream reading unit 500 is valid until the next job is completed. For example, the calibration control unit 800 obtains the processing time of the next job from the control unit 200, calculates the completion time of the next job, and compares this completion time with the time elapsed since the previous calibration of the downstream reading unit 500 within the calibration validity period B. In this way, the calibration control unit 800 checks whether the calibration validity period B of the downstream reading unit 500 is valid until the next job is completed.

[0106] The calibration control unit 800 proceeds to step S4050 if the calibration validity period B of the downstream reading unit 500 is valid until the completion of the next job (YES), and proceeds to step S4060 if the calibration validity period B of the downstream reading unit 500 is not valid until the completion of the next job (NO).

[0107] (Step S4050) The calibration control unit 800 reserves the calibration of the upstream reading unit 400 to be performed before the next job (before it starts). For example, the calibration control unit 800 reserves the calibration of the upstream reading unit 400 in the data table to be performed before the next job. Since the downstream reading unit 500 will not be used in the next job, the calibration control unit 800 reserves the calibration of the upstream reading unit 400.

[0108] (Step S4060) The calibration control unit 800 reserves the calibration of the upstream reading unit 400 and the downstream reading unit 500 to be performed before the next job. For example, the calibration control unit 800 reserves the calibration of the upstream reading unit 400 and the downstream reading unit 500 in the data table to be performed before the next job.

[0109] In other words, the calibration control unit 800 reserves calibration for both the upstream reading unit 400 and the downstream reading unit 500 if the calibration validity period B of the downstream reading unit 500 will expire before the next job is completed, when calibration of the upstream reading unit 400 is required.

[0110] (Step S4110) The calibration control unit 800 checks whether the downstream reading unit 500 will be used in the next job. If the downstream reading unit 500 will be used in the next job (YES), the calibration control unit 800 proceeds to step S4120; if the downstream reading unit 500 will not be used in the next job (NO), it proceeds to step S1050 shown in Figure 5. Since the downstream reading unit 500 will not be used in the next job, the calibration control unit 800 proceeds to step S1050 shown in Figure 5.

[0111] (Step S4120) The calibration control unit 800 checks whether the calibration validity period B has elapsed since the last calibration of the downstream reading unit 500. If the calibration validity period B of the downstream reading unit 500 has elapsed (YES), the calibration control unit 800 proceeds to step S4130. If the calibration validity period B of the downstream reading unit 500 has not elapsed (NO), the calibration control unit 800 proceeds to step S1050 shown in Figure 5.

[0112] (Step S4130) The calibration control unit 800 checks whether the upstream reading unit 400 will be used in the next job. If the calibration control unit 800 will use the upstream reading unit 400 in the next job (YES), it proceeds to step S4140; if it will not use the upstream reading unit 400 in the next job (NO), it proceeds to step S4150.

[0113] (Step S4140) The calibration control unit 800 checks whether the calibration validity period A of the upstream reading unit 400 is valid until the next job is completed. For example, the calibration control unit 800 obtains the processing time of the next job from the control unit 200, calculates the completion time of the next job, and compares this completion time with the time elapsed since the previous calibration of the upstream reading unit 400 within the calibration validity period A. In this way, the calibration control unit 800 checks whether the calibration validity period A of the upstream reading unit 400 is valid until the next job is completed. If the calibration control unit 800 confirms that the calibration validity period A of the upstream reading unit 400 is valid until the next job is completed (YES), it proceeds to step S4150; if the calibration validity period A of the upstream reading unit 400 is not valid until the next job is completed (NO), it proceeds to step S4160.

[0114] (Step S4150) The calibration control unit 800 reserves the calibration of the downstream reading unit 500 to be performed before the next job. For example, the calibration control unit 800 reserves the calibration of the downstream reading unit 500 in the data table to be performed before the next job. Since the upstream reading unit 400 will not be used in the next job, the calibration control unit 800 reserves the calibration of the downstream reading unit 500. The process then proceeds to step S1050 shown in Figure 5.

[0115] (Step S4160) The calibration control unit 800 reserves the calibration of the upstream reading unit 400 and the downstream reading unit 500 to be performed before the next job. For example, the calibration control unit 800 reserves the calibration of the upstream reading unit 400 and the downstream reading unit 500 in the data table to be performed before the next job. Then, the process proceeds to step S1050 shown in Figure 5.

[0116] In other words, the calibration control unit 800 reserves calibration for both the upstream reading unit 400 and the downstream reading unit 500 if the calibration validity period A of the upstream reading unit 400 expires before the completion of the next job when calibration of the downstream reading unit 500 is required.

[0117] Here, we will explain the method for determining the calibration validity period as described above, referring to the reserved job list shown in Figure 3.

[0118] Referring to the reserved job list shown in Figure 3, job ID=5 will print 100 copies x 200 pages = 20,000 sheets of A3 size paper. Therefore, depending on the timing of the previous proofreading of the upstream reading unit 400 and the downstream reading unit 500, it is possible that the validity period of at least one of the proofreading units may expire during printing.

[0119] In this case, if the upstream reading unit 400 is in use after the completion of job ID=4, and the calibration validity period A has elapsed since the last calibration of the upstream reading unit 400, then calibration of the upstream reading unit 400 is required. Furthermore, if the downstream reading unit 500 is in use, and the calibration validity period B of the downstream reading unit 500 will expire before the completion of the next job, then calibration of both the upstream reading unit 400 and the downstream reading unit 500 will be scheduled (see steps S4010 to S4060 above).

[0120] Furthermore, if the downstream reading unit 500 is in use after the completion of job ID=4, and the calibration validity period B has elapsed since the last calibration of the downstream reading unit 500, calibration of the downstream reading unit 500 is required. If the upstream reading unit 400 is in use, and the calibration validity period A of the upstream reading unit 400 will expire before the completion of the next job, calibration of both the upstream reading unit 400 and the downstream reading unit 500 will be scheduled (see steps S4110 to S4160 above).

[0121] As described above, when calibration of both the upstream reading unit 400 and the downstream reading unit 500 is scheduled, the calibration control unit 800 will simultaneously perform calibration of the upstream reading unit 400 and the downstream reading unit 500 in step S1020 shown in Figure 5, before the next job.

[0122] In this case, as described above, calibration of the upstream reading unit 400 and the downstream reading unit 500 will be carried out so that the calibration period for the upstream reading unit 400 and the calibration period for the downstream reading unit 500 overlap. Therefore, the calibration period can be shortened compared to when the calibration of the upstream reading unit 400 and the downstream reading unit 500 is carried out at different times. In addition, since the job will be printed after the calibration of the upstream reading unit 400 and the downstream reading unit 500 is completed, the frequency of calibration between jobs can be reduced, enabling continuous execution of jobs and suppressing a decrease in printing productivity.

[0123] Once the calibration validity period has been determined, it is checked whether there are any new jobs to be accepted (see step S1050 in Figure 5). If there are new jobs to be accepted, the process for adding the new jobs is performed.

[0124] [How to add a new job] The process for adding a new job will be explained below with reference to Figure 9. Figure 9 is a flowchart illustrating the subroutine in step S1060, which performs the process of adding a new job, as shown in the flowchart in Figure 5.

[0125] (Step S5010) The calibration control unit 800 adds the new job sent from the control unit 200 to its reserved job list. This adds the job settings for the new job to the reserved job list of the calibration control unit 800.

[0126] (Step S5020) The calibration control unit 800 checks whether the new job uses the upstream reading unit 400. For example, the calibration control unit 800 checks whether the new job uses the upstream reading unit 400 by checking whether the position correction mode is enabled in the job settings of the new job. If the new job uses the upstream reading unit 400 (YES), the calibration control unit 800 proceeds to step S5030, and if the new job does not use the upstream reading unit 400 (NO), it proceeds to step S5120.

[0127] (Step S5030) The calibration control unit 800 checks whether the upstream reading unit 400 has been calibrated. For example, the calibration control unit 800 checks whether the upstream reading unit 400 has been calibrated by referring to the data table. If the upstream reading unit 400 has been calibrated (YES), the calibration control unit 800 proceeds to step S5120; if the upstream reading unit 400 has not been calibrated (NO), it proceeds to step S5040.

[0128] (Step S5040) The calibration control unit 800 checks whether there is a calibration reservation for the downstream reading unit 500. For example, the calibration control unit 800 checks whether there is a calibration reservation for the downstream reading unit 500 by referring to the data table. If there is a calibration reservation for the downstream reading unit 500 (YES), the calibration control unit 800 proceeds to step S5050; if there is no calibration reservation for the downstream reading unit 500 (NO), it proceeds to step S5060.

[0129] (Step S5050) The calibration control unit 800 reserves the calibration of the upstream reading unit 400 and the downstream reading unit 500 to be performed before the start of a new job. Specifically, the calibration control unit 800 reserves the calibration of the upstream reading unit 400 to coincide with the timing of the calibration of the downstream reading unit 500, which is already reserved (scheduled to be performed before the start of a new job). For example, the calibration control unit 800 reserves the calibration of the upstream reading unit 400 in the data table so that its calibration timing matches the timing of the calibration of the downstream reading unit 500, which is already reserved. Then, the process proceeds to step S5120.

[0130] In other words, if the upstream reading unit 400 used by a new job is not yet calibrated, and there is a calibration reservation for the downstream reading unit 500, the calibration control unit 800 will add a calibration reservation for the upstream reading unit 400.

[0131] (Step S5060) The calibration control unit 800 checks whether there is a plan to perform image stabilization processing for a period longer than the calibration period of the upstream reading unit 400. For example, the calibration control unit 800 obtains the planned image stabilization processing schedule and processing time of the image forming unit 20 from the control unit 200. Then, the calibration control unit 800 determines whether the obtained processing time is longer than or equal to the calibration period of the upstream reading unit 400, thereby confirming whether there is a plan to perform image stabilization processing for a period longer than the calibration period of the upstream reading unit 400.

[0132] If the calibration control unit 800 plans to perform image stabilization processing for a period longer than the calibration period of the upstream reading unit 400 (YES), it proceeds to step S5070; otherwise, it proceeds to step S5080.

[0133] In this case, the calibration control unit 800 acquires the scheduled execution date and processing time for the image stabilization process of the image forming unit 20. However, if there is a process where the paper feeding interval is longer than the calibration period of the upstream reading unit 400, the calibration control unit 800 may acquire the scheduled execution date and processing time for that process. The calibration control unit 800 can then determine whether the acquired processing time is longer than or equal to the calibration period of the upstream reading unit 400 to confirm whether there is a scheduled execution date for a process longer than the calibration period of the upstream reading unit 400.

[0134] (Step S5070) The calibration control unit 800 reserves the calibration of the upstream reading unit 400 to be performed during image stabilization. For example, the calibration control unit 800 reserves the calibration of the upstream reading unit 400 in the data table to be performed during image stabilization. Then, the process proceeds to step S5120.

[0135] (Step S5080) The calibration control unit 800 reserves the calibration of the upstream reading unit 400 to be performed immediately before the start of a new job. For example, the calibration control unit 800 reserves the calibration of the upstream reading unit 400 in the data table to be performed immediately before the start of a new job. Then, the process proceeds to step S5120.

[0136] (Step S5120) The calibration control unit 800 checks whether the new job uses the downstream reading unit 500. For example, the calibration control unit 800 checks whether the new job uses the downstream reading unit 500 by checking whether the image correction mode is enabled in the job settings of the new job. If the new job uses the downstream reading unit 500 (YES), the calibration control unit 800 proceeds to step S5130, and if the new job does not use the downstream reading unit 500 (NO), it proceeds to step S1070 shown in Figure 5.

[0137] (Step S5130) The calibration control unit 800 checks whether the downstream reading unit 500 has been calibrated. For example, the calibration control unit 800 checks whether the downstream reading unit 500 has been calibrated by referring to the data table. If the downstream reading unit 500 has been calibrated (YES), the calibration control unit 800 proceeds to step S1070 shown in Figure 5, and if the downstream reading unit 500 has not been calibrated (NO), it proceeds to step S5140.

[0138] (Step S5140) The calibration control unit 800 checks whether there is a calibration reservation for the upstream reading unit 400. For example, the calibration control unit 800 checks whether there is a calibration reservation for the upstream reading unit 400 by referring to the data table. If there is a calibration reservation for the upstream reading unit 400 (YES), the calibration control unit 800 proceeds to step S5150; if there is no calibration reservation for the upstream reading unit 400 (NO), it proceeds to step S5160.

[0139] (Step S5150) The calibration control unit 800 reserves the calibration of the upstream reading unit 400 and the downstream reading unit 500 to be performed before the start of a new job. Specifically, the calibration control unit 800 reserves the calibration of the downstream reading unit 500 to coincide with the timing of the calibration of the upstream reading unit 400, which is already reserved (scheduled to be performed before the start of a new job). For example, the calibration control unit 800 reserves the calibration of the downstream reading unit 500 in the data table so that its calibration timing matches the timing of the calibration of the upstream reading unit 400, which is already reserved. The process then proceeds to step S1070 shown in Figure 5.

[0140] In other words, if the downstream reading unit 500 used by a new job has not been calibrated, and there is a calibration reservation for the upstream reading unit 400, the calibration control unit 800 will add a calibration reservation for the downstream reading unit 500.

[0141] (Step S5160) The calibration control unit 800 checks whether there is a plan to perform image stabilization processing for a period longer than the calibration period of the downstream reading unit 500. For example, the calibration control unit 800 obtains the planned image stabilization processing schedule and processing time of the image forming unit 20 from the control unit 200. Then, the calibration control unit 800 determines whether the obtained processing time is longer than or equal to the calibration period of the downstream reading unit 500, thereby confirming whether there is a plan to perform image stabilization processing for a period longer than the calibration period of the downstream reading unit 500.

[0142] If the calibration control unit 800 plans to perform image stabilization processing for a period longer than the calibration period of the downstream reading unit 500 (YES), it proceeds to step S5170; otherwise, it proceeds to step S5180.

[0143] In this case, the calibration control unit 800 acquires the scheduled execution date and processing time for the image stabilization process of the image forming unit 20. However, if there is a process where the paper feeding interval is longer than the calibration period of the downstream reading unit 500, the calibration control unit 800 may acquire the scheduled execution date and processing time for that process. The calibration control unit 800 can then determine whether the acquired processing time is longer than or equal to the calibration period of the downstream reading unit 500 to confirm whether there is a scheduled execution date for a process longer than the calibration period of the downstream reading unit 500.

[0144] (Step S5170) The calibration control unit 800 reserves the calibration of the downstream reading unit 500 to be performed during image stabilization. For example, the calibration control unit 800 reserves the calibration of the downstream reading unit 500 in the data table to be performed during image stabilization. Then, the process proceeds to step S1070 shown in Figure 5.

[0145] (Step S5180) The calibration control unit 800 reserves the calibration of the downstream reading unit 500 to be performed immediately before the start of a new job. For example, the calibration control unit 800 reserves the calibration of the downstream reading unit 500 in the data table to be performed immediately before the start of a new job. Then, the process proceeds to step S1070 shown in Figure 5.

[0146] As described above, when adding a new job, it is necessary to calibrate the upstream reading unit 400. If there is a calibration reservation for the downstream reading unit 500, an additional calibration reservation for the upstream reading unit 400 is made to reserve calibration for both the upstream reading unit 400 and the downstream reading unit 500. Similarly, when adding a new job, it is necessary to calibrate the downstream reading unit 500. If there is a calibration reservation for the upstream reading unit 400, an additional calibration reservation for the downstream reading unit 500 is made to reserve calibration for both the upstream reading unit 400 and the downstream reading unit 500.

[0147] In this case, the calibration control unit 800 will simultaneously perform calibration of the upstream reading unit 400 and the downstream reading unit 500 in step S1020 shown in Figure 5 before the start of a new job.

[0148] In this case, as described above, calibration of the upstream reading unit 400 and the downstream reading unit 500 will be carried out so that the calibration period for the upstream reading unit 400 and the calibration period for the downstream reading unit 500 overlap. Therefore, the calibration period can be shortened compared to when the calibration of the upstream reading unit 400 and the downstream reading unit 500 is carried out at different times. In addition, since the job will be printed after the calibration of the upstream reading unit 400 and the downstream reading unit 500 is completed, the frequency of calibration between jobs can be reduced, enabling continuous execution of jobs and suppressing a decrease in printing productivity.

[0149] As described above, in this embodiment, the image forming apparatus 1 includes a control unit 200 that controls the calibration of the upstream reading unit 400 and the downstream reading unit 500, respectively. When calibrations for the upstream reading unit 400 and the downstream reading unit 500 are scheduled or will be scheduled at different timings, the control unit 200 performs calibration of the upstream reading unit 400 and the downstream reading unit 500 simultaneously when performing one of the calibrations. Specifically, the control unit 200 performs calibration of the upstream reading unit 400 and the downstream reading unit 500 simultaneously so that the calibration period for the upstream reading unit 400 and the calibration period for the downstream reading unit 500 overlap.

[0150] In this embodiment of the image forming apparatus 1, calibration of the upstream reading unit 400 and the downstream reading unit 500 is performed so that the calibration period of the upstream reading unit 400 and the calibration period of the downstream reading unit 500 overlap. Therefore, the frequency of calibration between jobs can be suppressed, continuous execution of jobs can be enabled, and a decrease in printing productivity can be suppressed.

[0151] The embodiments described above are merely examples of how the present invention can be implemented, and the technical scope of the present invention should not be interpreted as being limited by these embodiments. In other words, the present invention can be implemented in various forms without departing from its gist or its main features.

[0152] For example, in the above embodiment, an image forming apparatus 1 having two measuring units (upstream reading unit 400 and downstream reading unit 500) was illustrated, but the present invention is also applicable to an image forming apparatus having three or more measuring units. In this case, when the control unit 200 performs calibration of one of the multiple measuring units, it should perform calibration of each of the multiple measuring units such that the calibration period for that one measuring unit overlaps with the calibration period for the other measuring units.

[0153] Furthermore, in the above embodiment, the image forming apparatus 1 has a correction unit 700 and a calibration control unit 800, but the control unit 200 may be configured to perform the functions of the correction unit 700 and the calibration control unit 800. [Explanation of Symbols]

[0154] 1. Image forming apparatus 10 Image Processing Unit 20 Image forming unit 30 Fixing section 40 Paper transport section 100 Image forming apparatus main unit 200 Control Unit 300 Paper feed section 400 Upstream Reading Unit 410 Sensor 420 Calibration Department 500 Downstream reading unit 510 Sensor 520 Proofreading Department 600 Paper output section 700 Correction Unit 800 Calibration Control Unit

Claims

1. In an image forming apparatus that executes multiple jobs, each with its own set of instructions for forming an image on a recording medium, A plurality of measuring units that measure information related to the recording medium, A control unit that controls the calibration of each of the aforementioned multiple measuring units, Equipped with, With regard to the calibration of the plurality of measuring units, if the timing of the calibration already reserved or newly reserved by the control unit differs for each of the plurality of measuring units, the control unit performs the calibration of one of the plurality of measuring units such that the calibration period from the start to the end of the calibration for that one measuring unit and the calibration period from the start to the end of the calibration for the other measuring units overlap in at least part. Image forming apparatus.

2. The first of the plurality of measuring units measures information about the recording medium before image formation, The second measurement unit among the plurality of measurement units measures information about the recording medium after image formation. The image forming apparatus according to claim 1.

3. The control unit, In the first measurement unit, once the first validity period has elapsed since the previous calibration, the next calibration is scheduled. In the second measurement unit, once the second validity period has elapsed since the previous calibration, the next calibration is scheduled. The image forming apparatus according to claim 2.

4. When either the first or second validity period has elapsed, the control unit performs calibration of the first measurement unit and the second measurement unit, respectively, such that the calibration period of the first measurement unit and the calibration period of the second measurement unit overlap in at least part. The image forming apparatus according to claim 3.

5. The control unit, If the validity period of the other of the first or second validity period expires before a job using a measuring unit is completed, the calibration of the first and second measuring units shall be performed before the start of the job so that the calibration periods of the first and second measuring units overlap in at least part. The image forming apparatus according to claim 4.

6. The control unit, A first correction mode calculates a first correction value for the image forming unit based on the measurement results of the first measurement unit, A second correction mode is used to calculate a second correction value in the image forming unit based on the measurement results of the second measurement unit. It has, If, in multiple jobs, there is one or more jobs that perform the first correction mode and one or more jobs that perform the second correction mode, the first measurement unit and the second measurement unit are calibrated before the start of the first job. The image forming apparatus according to claim 3.

7. The control unit, If a job added during the execution of the aforementioned multiple jobs performs either the first correction mode or the second correction mode, and the calibration of one of the measurement units corresponding to the correction mode performed by the added job has not yet been performed, and the validity period of the other measurement unit has elapsed by the time the added job starts, then the calibration of the first measurement unit and the second measurement unit shall be performed by the time the added job starts, such that the calibration period of the first measurement unit and the calibration period of the second measurement unit overlap in at least part. The image forming apparatus according to claim 6.

8. The control unit, If the calibration of the other measuring unit is not performed before the start of the added job, the calibration of the other measuring unit will be performed immediately before the start of the added job. The image forming apparatus according to claim 7.

9. The control unit, If a job added during the execution of the aforementioned multiple jobs performs at least one of the first correction mode and the second correction mode, and the calibration of the measurement unit corresponding to the correction mode performed by the added job has not been performed, and the paper feeding interval for feeding the recording medium to the image forming unit is longer than or equal to the calibration period of the measurement unit, then the calibration of the measurement unit is performed during the paper feeding interval. The image forming apparatus according to claim 6.

10. The first measuring unit includes one of a CCD, CIS, or spectrophotometer. The second measuring unit includes one of the following: CCD, CIS, or spectrophotometer. The image forming apparatus according to claim 2.

11. A calibration method for an image forming apparatus, in which, when executing multiple jobs in which instructions for forming an image on a recording medium are set, calibration is performed on multiple measuring units that measure information about the recording medium, In the image forming apparatus, if the timing of calibration for the plurality of measuring units already reserved or newly reserved by the image forming apparatus differs for each of the plurality of measuring units, when calibration is performed for one of the plurality of measuring units, the calibration of the plurality of measuring units is performed such that the calibration period from the start to the end of calibration for that one measuring unit and the calibration period from the start to the end of calibration for the other measuring units overlap in at least part. Calibration method.

12. A calibration program that performs calibration of multiple measuring units that measure information about the recording medium, when executing multiple jobs, each of which has set instructions for forming an image on the recording medium, On the computer, A process for reserving the calibration for the plurality of measuring units, If the timing of the calibration that is already reserved or newly reserved by the reservation process differs among the multiple measurement units, when performing calibration on one of the multiple measurement units, the calibration process for the multiple measurement units is performed such that the calibration period from the start to the end of the calibration on that one measurement unit and the calibration period from the start to the end of the calibration on the other measurement units overlap in at least part. To execute Calibration program.

Images