Image forming apparatus, control method thereof, and program

Abstract

To provide an image forming apparatus capable of suppressing a decrease in productivity due to switching of paper feed trays due to a paper shortage or the like, and outputting printed matter with the print position appropriately corrected. [Solution] The system comprises a paper feed unit 10 having multiple switchable paper feed trays 12 and feeding paper from one selected from the multiple paper feed trays 12, a reading unit 40 that reads the dimensions of the recording medium fed from the paper feed unit 10 before image formation and outputs the read value, an image correction unit 34 that uses the read value to calculate a correction value for the position of the image to be formed on the recording medium, an image forming unit 20 that forms the image on the recording medium based on the correction value, and a recording medium management unit 32 that links recording medium information including a read reference value to the paper feed tray 12 and manages it, and the recording medium management unit 32 selects the paper feed tray 12 that matches a specified item of the recording medium information as the switching destination, and the image correction unit 34 calculates the correction value based on the amount of change in the read value relative to the read reference value.

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus, a control method thereof, and a program. [Background technology]

[0002] Some image forming devices have a function to keep the position of the image to be formed on the paper (hereinafter also referred to as "print position") constant, and adjust the print position each time the paper feed unit or paper feed tray is switched. For example, Cited Document 1 describes an image forming device that prompts the user to adjust the print position when switching paper feed trays due to a paper shortage or the like. The print position refers to the position of the image relative to, for example, the edge of the paper. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-66815 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the print position is adjusted when the paper feed tray is switched, the printed matter designated by the user cannot be output until the adjustment is completed, which may result in a decrease in productivity. The present invention has been made to solve such problems, and aims to provide an image forming device that can suppress the decline in productivity that occurs when switching paper feed trays due to running out of paper, etc., and can output printed materials with the printing position appropriately corrected. [Means for solving the problem]

[0005] In order to solve the above problems, an image forming apparatus, a control method thereof, and a program according to the present invention have the following configurations (1) to (10). (1) An image forming apparatus comprising: a paper feed unit having a plurality of switchable paper feed trays and feeding paper from one selected from the plurality of paper feed trays; a reading unit reading the dimensions of a recording medium fed from the paper feed unit before image formation and outputting a read value; an image correction unit using the read value to calculate a correction value for the position of an image to be formed on the recording medium; an image forming unit forming an image on the recording medium based on the correction value; and a recording medium management unit linking recording medium information, which is information about the recording medium including a read reference value registered as a standard for the read value, to the paper feed tray and managing it; wherein the recording medium management unit selects a paper feed tray from the plurality of paper feed trays that matches a predetermined item of the recording medium information as a switching destination, and the image correction unit calculates the correction value based on the amount of change in the read value relative to the read reference value.

[0006] (2) In the image forming apparatus described in (1), if a reading reference value is not registered in the recording medium information of the paper feed tray to which the switch is made, the image correction unit calculates the correction value using the reading reference value of the paper feed tray before the switch. (3) In an image forming apparatus as described in (1), when the difference in the reading reference value between the paper feed tray to which the switch is made and the paper feed tray before the switch is greater than or equal to a predetermined threshold, the reading unit reads the recording medium fed from the paper feed tray to which the switch is made and outputs the reading value, and the recording medium management unit updates the reading reference value of the paper feed tray to which the switch is made with the output reading value.

[0007] (4) An image forming apparatus as described in (3), wherein the paper feed unit predicts a shortage of the recording medium in the job before starting the image formation job and pre-selects a paper feed tray to switch to, and the recording medium management unit updates the reading reference value before starting the job. (5) In an image forming apparatus as described in (1), if the elapsed time since registration of the reading reference value of the paper feed tray to which the switch is made is greater than or equal to a predetermined time, the reading unit reads the recording medium fed from the paper feed tray to which the switch is made and outputs the reading value, and the recording medium management unit updates the reading reference value of the paper feed tray to which the switch is made with the output reading value.

[0008] (6) An image forming apparatus as described in (5), wherein the paper feed unit predicts a shortage of the recording medium in the job before starting the image formation job and pre-selects a paper feed tray to switch to, and the recording medium management unit updates the reading reference value before starting the job. (7) An image forming apparatus as described in (1), in which, before the start of an image forming job, a paper feed tray to which the image forming job will be switched is selected in advance by predicting a shortage of the recording medium in the job, and if the reading reference value is not registered in the recording medium information of the paper feed tray to which the image forming job will be switched, the reading unit reads the recording medium fed from the paper feed tray to which the image forming job will be switched and outputs the reading value, and the recording medium management unit registers the output reading value as the reading reference value of the paper feed tray to which the image forming job will be switched before the start of the job. (8) The image forming apparatus according to any one of (1) to (7), wherein the predetermined items of the recording medium information are the type, basis weight, and size of the recording medium.

[0009] (9) A control method including the steps of: a paper feed unit selecting one of a plurality of switchable paper feed trays and feeding paper; a reading unit reading the dimensions of the fed recording medium before image formation and outputting the read value; a recording medium management unit linking recording medium information, which is information about the recording medium including a read reference value registered as a standard for the read value, to the paper feed tray and managing it; in switching the paper feed tray, selecting the paper feed tray that matches a predetermined item of the recording medium information as the switching destination; and an image forming unit correcting the position of the image on the recording medium based on the amount of change in the read value relative to the read reference value and forming the image.

[0010] (10) A program for causing a computer to execute the following steps: selecting one of a plurality of switchable paper feed trays and feeding paper; reading the dimensions of the recording medium to be fed before image formation and outputting the read value; linking and managing recording medium information, which is information about the recording medium including a read reference value to be registered as a standard for the read value, to the paper feed tray; selecting, when switching the paper feed tray, the paper feed tray that matches a predetermined item of the recording medium information; and correcting the position of the image on the recording medium based on the amount of change in the read value relative to the read reference value to form the image. [Effects of the Invention]

[0011] According to the present invention, it is possible to suppress a decrease in productivity that would otherwise occur if the paper feed tray had to be switched due to a paper shortage or the like, and to output printed material with the print position appropriately corrected. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a side view schematically illustrating an image forming apparatus according to an embodiment. [Figure 2] FIG. 1 is a block diagram illustrating a hardware configuration of an image forming apparatus according to an embodiment. [Figure 3] 10 is a table illustrating an example of a job list for image formation. [Figure 4] FIG. 2 is a block diagram illustrating a part of the functional configuration of a central control unit according to the embodiment. [Figure 5] 10 is a table illustrating examples of items and values ​​of recording medium information (paper information). [Figure 6] 1 is a flowchart illustrating a processing flow in the image forming apparatus according to the first and second embodiments. [Figure 7] 10 is a flowchart illustrating a process flow of paper feed tray switching in the first embodiment. [Figure 8] 10 is a flowchart illustrating a process flow of paper feed tray switching in the second embodiment. [Figure 9] 10 is a flowchart illustrating a reference value registration process. [Figure 10] 10 is a flowchart illustrating a processing flow in an image forming apparatus according to a third embodiment. [Figure 11] 10 is a flowchart illustrating a process flow of a reference value registration advance confirmation. DETAILED DESCRIPTION OF THE INVENTION

[0013] Embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments.

[0014] [First embodiment] An image forming apparatus 1 according to a first embodiment will be described with reference to FIGS. 1 to 7. The image forming apparatus 1 is an apparatus that forms an image on a recording medium (hereinafter also referred to as "paper") such as paper or overhead projector (OHP) sheets using electrophotography, and is, for example, a printer, copier, or multifunction peripheral. As illustrated in FIG. 1, the image forming apparatus 1 includes a paper feed unit 10, an image forming unit 20, a paper discharge unit 70, a reading unit 40, and a display unit 60. The recording medium (paper) is transported along a transport path 14 from the paper feed unit 10 on the upstream side to the paper discharge unit 70 on the downstream side, and an image is formed in the image forming unit 20. A central control unit 50, an auxiliary storage device 53, and a communication interface 54 that control the image forming apparatus 1 are disposed in the image forming unit 20. Each component of the image forming apparatus 1 will be described below.

[0015] (Paper feed section) The paper feed unit 10 is a device that stores and supplies paper. The paper feed unit 10 has multiple switchable paper feed trays, and feeds paper from one selected from the multiple paper feed trays. Here, the paper feed unit 10 has seven paper feed trays 12A to 12G, and can store paper in a classified manner. The number of paper feed trays 12 is not particularly limited. Note that the image forming apparatus 1 may be provided with multiple paper feed units 10. The paper feed unit 10 feeds paper from one selected paper feed tray 12. The paper feed tray 12 can be freely switched when paper runs out, paper needs to be changed, or when the user specifies otherwise. A paper out state occurs when the selected paper feed tray 12 runs out of paper.

[0016] (Image forming section) Image forming section 20 is a device that forms an image on a recording medium based on a position correction value calculated by image correction section 34, which will be described later. Image forming section 20 has image forming units 21 that form a toner image, a primary transfer section 25 that transfers the image to a belt-like intermediate transfer body 24, a secondary transfer section 26 that further transfers the toner image from intermediate transfer body 24 to a recording medium (paper), and a fixing section 27 that fixes the toner image transferred to the paper. Here, image forming section 20 has four image forming units 21 corresponding to four colors: yellow (Y), magenta (M), cyan (C), and black (K).

[0017] The image forming unit 21 is a device that forms a toner image on the photosensitive drum 22. The image forming unit 21 has the photosensitive drum 22 on which an electrostatic latent image is formed, and a developing unit 23 that converts the electrostatic latent image into a toner image using a developer containing toner. In addition to the developing unit 23, the image forming unit 21 also has a charging unit that charges the photosensitive drum 22, an exposure unit that exposes the photosensitive drum 22 to light to form an electrostatic latent image, a cleaning unit that collects remaining toner from the photosensitive drum 22, etc. At primary transfer unit 25, toner images of the respective colors Y, M, C, and K are transferred onto intermediate transfer body 24 so as to be superimposed on each other. At secondary transfer unit 26, the color toner images are transferred onto paper by being pressed against the paper. At fixing unit 27, the toner images are fixed to the paper by, for example, heat and pressure bonding between heating roller 27A and pressure roller 27B.

[0018] (Reading unit) The reading unit 40 is a device that reads the dimensions of a recording medium (paper). The reading unit 40 is disposed between the paper feed unit 10 and the image forming unit 20, and reads the dimensions of the paper before image formation and outputs the read values. The read values ​​are the vertical and horizontal dimensions of the paper, and are expressed in units of length (mm) and number of pixels (dots). Paper varies in size from one sheet to another, even within the same production lot, and this is called cutting variation. The image forming apparatus 1 can correct this cutting variation to form an image. The reading unit 40 reads the dimensions of the paper by capturing an image of the paper being transported on the transport path 14 with a sensor 45. The sensor 45 has, for example, an imaging element of the CCD (Charge Coupled Device) type that optically reduces and reads the image of the object to be read, or a CIS (Contact Image Sensor) type that reads at 1x magnification.

[0019] (Display) The display unit 60 is an input / output device that displays information such as the operating status of the image forming apparatus 1 and accepts operations and inputs from the user. The display unit 60 functions as an interface for the user. The display unit 60 has, for example, a touch panel screen. The display unit 60 receives information for displaying the operating status from the central control unit 50, and can display on the screen when an out-of-paper condition occurs to notify the user. The user can also input information such as the selection or switching of the paper feed tray 12, the number of sheets to print, and paper information (described later) from the display unit 60.

[0020] (Paper ejection section) The paper discharge unit 70 is a device that discharges paper sent from the image forming unit 20. The paper discharge unit 70 is arranged downstream of the image forming unit 20, and can store paper after image formation in a paper discharge tray 72. The paper discharge unit 70 may have multiple paper discharge trays 72. Although not shown, the image forming apparatus 1 is provided with a conveying device that conveys the paper along the conveying path 14. The conveying device may have a mechanism that turns over the paper that has passed through the fixing unit 27 and returns it upstream of the secondary transfer unit 26.

[0021] (Central Control Unit) The central control unit 50 is a device that controls the image forming apparatus 1. As illustrated in Fig. 2, the central control unit 50 has a central processing unit (CPU) 51 and a main memory device 52, and performs information processing related to the control of the image forming apparatus 1. The main memory device 52 is a ROM or RAM. The central control unit 50 is mutually connected to an auxiliary memory device 53 such as a hard disk, a communication interface 54 that connects to the Internet or a local area network (LAN), and other devices of the image forming apparatus 1 via a bus 55. The central control unit 50 receives image source data that is the source data for image formation, generates image formation data, and transmits it to the image forming unit 20 to execute image formation. It also receives job information such as the number of pages and paper size, generates an image formation job (hereinafter simply referred to as a "job"), and controls paper feeding / discharging and paper transport.

[0022] An example of a job list listing the generated jobs is shown in Figure 3. Each row in Figure 3 represents one job, and five jobs have been generated in this example. Each job is assigned a number (job number) in the order in which it was generated, and is managed by job number. When processing of job number 1 is completed, jobs are processed one by one in the order of the job list, with job number 2 being processed next, and so on. "Number of pages" is the number of pages of image formation data. "Single-sided / Double-sided" specifies whether the image is formed on one side or both sides of the paper. "Size" is the size of the paper, as indicated by standards such as A3 or A4. "Paper type" is the type of recording medium, such as plain paper or coated paper, depending on the material and surface treatment. "Basis weight" is the number of grams of paper per square meter, and is expressed in g / m 2 The unit of measurement used is gsm. Basis weight is a value that indicates the thickness of the paper if the paper type is the same.

[0023] "Tray designation" refers to the designated paper feed tray 12. For example, when a user wants to use a specific paper, the user can designate the paper feed tray 12 that contains that paper. Tray designation is performed by specifying one of the paper feed trays 12, such as "Tray 1." When tray designation is "automatic," the central control unit 50 selects the paper feed tray 12 according to the paper size, paper type, basis weight, and other conditions preset by the user. For example, tray 1 can correspond to paper feed tray 12A in FIG. 1, and tray 2 can correspond to paper feed tray 12B. "Cutting variation correction" allows the user to designate whether or not to perform cutting variation correction during image formation. "ON" specifies that cutting variation correction is performed, and "OFF" specifies that cutting variation correction is not performed. 4 is a block diagram illustrating a portion of the functional configuration of the central control unit 50. The central control unit 50 has a control unit 30, a recording medium management unit (paper management unit) 32, and an image correction unit 34, and the control unit 30 is connected to the reading unit 40, the paper feed unit 10, the display unit 60, and the image forming unit 20.

[0024] (Control unit) The control unit 30 is a means for controlling other devices, etc. The control unit 30 acquires data from other devices, etc., makes decisions based on predetermined conditions, sends signals instructing operations, and causes the image forming apparatus 1 to function. Note that Fig. 4 illustrates some of the connections between the control unit 30 and other devices, such as those related to adjusting the print position and switching the paper feed unit, and does not illustrate the rest. The control unit 30 instructs the reading unit 40 to read the paper and obtains the read value.

[0025] The control unit 30 specifies the paper feed tray to be selected and instructs the paper feed unit 10 to switch. Then, the control unit 30 obtains information from the paper feed unit 10, such as whether the selected paper feed tray has run out of paper and the number of sheets of paper remaining in each paper feed tray. The control unit 30 sends and displays to the display unit 60 display information such as when the paper feed tray is out of paper and the operating status of the image forming apparatus 1. The control unit 30 also receives input of paper information and designation of a paper feed tray from the user via the display unit 60.

[0026] The control unit 30 controls the image formation of the image forming unit 20. In addition to signals for this control, the control unit 30 transmits image formation data, which is data on the image to be formed, and correction values ​​for correcting cutting variations, to the image forming unit 20. In this way, the image forming unit 20 corrects the position at which the image is formed on the recording medium. The control unit 30 exchanges paper information with the paper management unit 32, instructs the paper management unit 32 to register or update the paper information, and selects the paper feed tray to switch to. The control unit 30 also sends the read value to the paper management unit 32 and instructs the paper management unit 32 to register or update the read reference value. The control unit 30 sends the read reference value and the read value to the image correction unit 34, instructs the image correction unit 34 to calculate a correction value, and acquires the calculated correction value.

[0027] (Recording Media Management Department (Paper Management Department)) The recording medium management unit (paper management unit) 32 is a means for managing recording medium information (paper information), which is information about the recording media (paper) stored in the paper feed tray. The paper management unit 32 manages the paper information by linking it to the paper feed tray. This allows image formation to be performed in accordance with the characteristics of the paper, even when the paper feed tray is switched. Paper information can be input from the outside via a communication interface, and can also be input from the display unit 60. 5, paper information 16 has items 17 that are information about paper, and here, five items 17 are set and values ​​are registered: "size," "paper type," "basis weight," "reading reference value," and "reading reference registration date." The number and contents of items 17 can be set by the user.

[0028] "Size," "Paper type," and "Basis weight" are the same as in the job list. "Reading reference value" is a value registered as the reference value for the reading value. The reading reference value is the vertical and horizontal dimensions of the paper, just like the reading value, and is expressed in units of length (mm) or number of pixels (dots). The reading reference value serves as the reference for the printing position when correcting for cutting variations, and is used to calculate the correction value in the image correction unit 34. The image forming device 1 has a reading reference value set in the paper information item. This allows the reading reference value to be managed in association with the paper feed tray, and the accuracy of trimming variation correction can be maintained even when the paper feed tray is switched. The "reading reference registration date" is an item that displays the date on which the reading reference value was registered. Note that the date and time can also be displayed, including the time when the reading reference value was registered.

[0029] The paper management unit 32 manages the set of values ​​in item 17 by linking them to paper feed trays. Also, to the left of item 17 is a "paper profile" column. A paper profile is a name that can be given to a set of values ​​in item 17, and paper information can be identified by the paper profile. It is also possible to apply the same paper profile to multiple paper feed trays. In other words, the same paper information can be applied to different paper feed trays and managed collectively by the paper profile. For example, for Tray 1, the following values ​​are registered for the items (Size, Paper Type, Basis Weight, Scan Reference Value, Scan Reference Registration Date): (A4, Plain Paper, 60gsm, 1170dot x 825dot, 2024 / 6 / 14). No paper profile is registered. For Tray 2, the following values ​​are registered with a paper profile called "Book 1": (A3, Fine Paper, 80gsm, 2348dot x 1661dot, 2024 / 5 / 25). The same paper information for the paper profile "Book 1" is also registered for Tray 7, and the same paper profile "Book 1" is applied to both paper trays.

[0030] If a paper tray runs out during a job, the paper feed tray is switched based on the paper information. In this switching, the paper management unit 32 selects, as the destination paper feed tray, one of multiple paper trays that matches certain items of the paper information. The certain items are, for example, three items: size, paper type, and basis weight, and this is also true for other embodiments. This makes it possible to obtain reading reference values ​​from the paper information of the destination paper feed tray, allowing image formation to continue with the print position appropriately corrected without causing a decrease in productivity. The certain items can be set in advance by the user. A reading reference value is used in the cutting variation correction. The paper management unit 32 sends the reading reference value registered in the paper information of the paper feed tray to the control unit 30. On the other hand, in a job with cutting variation correction, if a value is not registered in the reading reference value of the paper information of the paper feed tray to the switching destination, that is, if the reading reference value of the switching destination is not registered, the reading reference value cannot be sent.

[0031] In the example of FIG. 5, the reading reference value and the reading reference registration date are not registered for the paper profile "Book 2." For example, when switching from Tray 2 for "Book 1" to Tray 6 for "Book 2," the reading reference value is not registered in the paper information for the destination paper tray. In this way, when the reading reference value for the destination tray is not registered, the paper management unit 32 can register the reading reference value before the switch in the paper information for the destination tray and send it to the control unit 30. In other words, the reading reference value before the switch, "2348 dots x 1661 dots," is sent as the reading reference value for "Book 2." This allows the image forming device 1 to continue correcting cutting variations without interrupting image formation. The paper feed tray is also switched when changing the type of paper, and can also be switched by a user operation.

[0032] (Image correction section) The image correction unit 34 is a means for calculating a correction value for the position of an image to be formed on a recording medium (paper) using the read values ​​read by the reading unit 40. The image correction unit 34 calculates a correction value for the position of the image on the paper using the read values. The position of the image on the paper can be specified, for example, by the distance from the edge of the paper. If there is variation in the cutting of the paper, it is preferable that the image is formed at a position that is a constant distance from the edge of the paper. The user can freely set the distance from which edge of the paper the image should be formed.

[0033] The correction value is calculated based on the amount of change in the read value relative to the read reference value. The read reference value is a value obtained from paper information in the paper feed tray. The read value is a value read by the reading unit 40 for each sheet of paper. The read reference value and the read value are transmitted from the control unit 30. The correction value is the amount of adjustment for the printing position in the vertical and horizontal directions on the surface of the paper. Cutting variation correction is performed by translating the image so that the distance Δ from the edge of the paper to the image does not change, without enlarging or reducing the image. The edge of the paper that is used as the reference for the printing position is specified by the user. The image correction unit 34 compares the read reference value with the read value, and if the read value is smaller than the read reference value, it decreases the distance Δ by, for example, δ1. If the read value is larger, it increases the distance Δ by, for example, δ2. These δ1 and δ2 are the correction values.

[0034] Image forming apparatus 1 configured as described above calculates a correction value based on the amount of change in the read value relative to the read reference value, correcting for trimming variations for each sheet of paper, and can form images. It then selects a paper feed tray that matches certain items of paper information as the destination, and the paper information includes a read reference value that is registered as a reference for the read value and is managed in association with the paper feed tray. This makes it possible to obtain the read reference value from the paper information of the destination paper feed tray, enabling printed materials to be output with the print position appropriately corrected without reducing productivity.

[0035] In addition, if the reading reference value for the paper feed tray to which the switch is made is not registered, the value registered in the paper information before the switch is used, thereby continuing to correct cutting variations and performing image formation, and prioritizing productivity in image formation. If trimming variation correction is not performed, the print position can be set based on the standard values ​​of the dimensions defined by the paper size. Also, if trimming variation correction is performed and the reading reference value is not registered for the paper feed tray to be switched to, the user can set it so that cutting variation correction is not performed and image formation continues.

[0036] [Second embodiment] Next, an image forming apparatus according to the second embodiment will be described. In the first embodiment, if a paper shortage occurs during a job and a reading reference value is registered in the paper information of the paper feed tray to which the job is switched, image formation continues as is. In contrast, in the second embodiment, even if a reading reference value is registered in the paper information of the paper feed tray to which the job is switched, the reading reference value is updated if the registration date is old or if there is a large difference from the reading reference value before the switch. Other than this, the second embodiment is the same as the first embodiment. If the paper runs out during a job, the paper management unit 32 selects a paper feed tray that matches a predetermined item of the paper information, and the control unit 30 instructs the paper feed tray to be switched. If the reading reference value is not registered in the paper information of the switched-to paper tray, the reading reference value of the paper information before the switch is registered in the paper information of the switched-to paper tray, as in the first embodiment.

[0037] On the other hand, if a reading reference value is registered in the paper information of the switching destination, the control unit 30 calculates the difference between the reading reference value before switching and the reading reference value after switching. If the difference is equal to or greater than a predetermined threshold, the control unit 30 executes "reference value registration." Reference value registration is a process in which, at the instruction of the control unit 30, the reading unit 40 reads paper fed from the paper feed tray of the switching destination and outputs the reading value, and the paper management unit 32 registers the output reading value as a reading reference value. The reading reference value of the switching destination is updated by the reference value registration. Furthermore, if the time that has passed since the registration of the read reference value of the switching destination is equal to or greater than a predetermined time, the reference value registration is also executed and the read reference value of the switching destination is updated. That is, the read reference value is updated when either the difference between the read reference values ​​is equal to or greater than a predetermined threshold value, or the time that has passed since the registration of the read reference value is equal to or greater than a predetermined time.

[0038] The predetermined threshold value is, for example, 1% of the reading reference value before switching. The predetermined time is, for example, 30 days. Both can be freely set by the user. Even if the reading reference value is registered, if the registration date is old or if there is a large difference from the reading reference value before switching, the correction value may not be calculated correctly. If image formation continues without the correction value being calculated correctly, the quality expected by the user will not be achieved, and productivity will be greatly reduced if the job has to be re-executed, etc.

[0039] In the image forming apparatus according to the second embodiment, when switching between paper feed trays, even if a reading reference value is registered in the paper information of the destination tray, if the difference between the reading reference value before switching and the reading reference value after switching is equal to or greater than a predetermined threshold, or if the elapsed time since registration is equal to or greater than a predetermined time, the reading unit reads the paper fed from the destination paper feed tray and outputs the reading value, and the paper management unit updates the reading reference value of the destination tray with the output reading value. This maintains the accuracy of cutting variation correction and prevents a decrease in productivity. It is assumed here that the job is started with the correct value registered as the reading reference value before switching. The user can instruct the reading reference value to be updated before starting the job or by interrupting the job.

[0040] [Third embodiment] Next, an image forming apparatus according to a third embodiment will be described. In the first embodiment, if a paper shortage occurs and a reading reference value is not registered in the paper information of the destination tray, the reading reference value before switching is used. In contrast, in the third embodiment, before starting a job, it is checked whether there is a paper shortage and a paper feed tray to switch to is selected in advance. Then, if a reading reference value is not registered in the paper information of the destination tray, a reading reference value is registered (reference value registration) for the paper feed tray to switch to. Other than this, the system is the same as the first embodiment. Before starting an image formation job, the control unit 30 acquires the number of remaining sheets in the selected paper feed tray from the paper feed unit 10 and compares it with the number of sheets set for the job. If the number of remaining sheets in the selected paper feed tray is less than the number of sheets in the job, the control unit 30 instructs the paper management unit 32 to preselect a paper feed tray to switch to.

[0041] The paper management unit 32 selects a paper feed tray that matches a predetermined item of the paper information, and notifies the control unit 30 whether or not a read reference value is registered in the paper information of the selected paper feed tray. If the reading reference value has not been registered, the control unit 30 instructs "registration of reference value" to the paper information of the paper feed tray to which the switch is made.

[0042] Reference value registration is a process in which paper is fed from the target paper feed tray, the reading unit 40 reads the dimensions and outputs the read value, and the paper management unit 32 registers the read value as the reading reference value for the target paper feed tray. Note that if a paper profile is applied to the target paper feed tray, the read value will be registered as the reading reference value for the paper profile. Therefore, if the same paper profile is applied to multiple paper feed trays, the new reading reference value will be reflected in those paper feed trays as well. The control unit 30 registers the reference value before starting a job, and then starts the job. If the paper feed tray runs out of paper, the control unit 30 switches to the paper feed tray that was previously selected and continues image formation.

[0043] The image forming apparatus according to the third embodiment predicts whether a paper feed tray will run out of paper before a job starts and registers the reference value. Therefore, even if the paper feed tray runs out of paper after the job starts, the image forming apparatus can continue to correct cutting variations using the read reference value of the destination without interrupting image formation, thereby improving productivity. In addition, it can reduce the need for users to interrupt jobs after the job starts. The first to third embodiments can be combined with two or more of these. For example, the reference value registration before the start of a job in the third embodiment can be performed in the second embodiment, and the read reference value can be updated in advance before the start of a job.

[0044] [Processing of image forming device] Next, the flow of processing performed by the image forming apparatus according to the embodiment will be described. Here, an example of the flow of processing for forming an image on paper (hereinafter also referred to as "printing processing") will be described for each of the first to third embodiments.

[0045] (Printing process of the first embodiment) The printing process S1 in the image forming apparatus 1 according to the first embodiment will be described below. Fig. 6 is a flowchart illustrating the flow of the printing processes S1 and S2. <Step S1010: Get job> First, the control unit 30 acquires the first job from the job list. <Step S1020 Paper tray selection> The control unit 30 acquires page settings from the job and selects a paper feed tray based on the page settings. The page settings refer to information necessary for forming an image on paper, such as paper size and tray designation.

[0046] <Step S1030 Paper out?> Control unit 30 acquires the amount of paper remaining (number of remaining sheets of paper) in the selected paper feed tray from paper feed unit 10. If there is paper remaining, the process proceeds to step S1070. If there is no paper remaining, the process proceeds to step S1040A. <Step S1040A: Switch paper tray> The control unit 30 instructs the paper feed unit 10 to "switch paper feed tray." In the first embodiment, "switch paper feed tray" is step S1040A, and will be described separately with reference to FIG. 7. If a paper feed tray such as "Tray 1" is specified in the "Tray Designation" of the job, the control unit 30 suspends the printing process and displays an out-of-paper message on the display unit 60. It is desirable that the control unit 30 then confirms with the user whether to replenish the paper feed tray with paper or switch to another paper feed tray before executing "switch paper feed tray."

[0047] <Step S1050 Is there a destination paper tray?> The control unit 30 checks whether a destination paper feed tray has been selected. If a paper feed tray has been selected (Yes), the process proceeds to step S1070. If not (No), the process proceeds to step S1060. <Step S1060 Printing Interruption> The control unit 30 displays on the display unit 60 that paper needs to be replenished, and suspends processing until the paper feed tray is replenished with paper and the paper feed unit 10 detects that there is still paper remaining.

[0048] <Step S1070 Paper Feed> The control unit 30 instructs the paper feed unit 10 to feed paper from the selected paper feed tray. <Step S1080: Cutting variation correction enabled?> The control unit 30 refers to the job and checks whether the cutting variation correction is enabled. If it is enabled (Yes), the process proceeds to step S1090, and if it is disabled (No), the process proceeds to step S1140.

[0049] <Step S1090 Is the reference value registered?> The control unit 30 queries the paper management unit 32 to confirm whether a reading reference value is registered for the selected paper feed tray. The paper management unit 32 manages paper information, which is information about the paper to be fed, by linking it to the paper feed tray. If a reading reference value is registered (Yes), the process proceeds to step S1110. If it is not registered (No), cutting variation correction is not performed, and the process proceeds to step S1140. <Step S1110: Read Reference Value> The control unit 30 acquires the reading reference value of the selected paper feed tray from the paper management unit 32 .

[0050] <Step S1120: Reading Paper Before Image Formation> The control unit 30 instructs the reading unit 40 to read the paper fed for image formation. The reading unit 40 responds to the control unit 30 with the reading result as a read value. <Step S1130: Calculate and set print position correction value> The control unit 30 notifies the read reference value and the read value to the image correction unit 34. The image correction unit 34 calculates the amount of change in the read value (the dimensions of the fed paper) from the read reference value and the read value, and calculates a correction value. The control unit 30 notifies the image forming unit 20 of the correction value and instructs it to correct the print position.

[0051] <Step S1140 Image Formation> The control unit 30 instructs the image forming unit 20 to form an image of the current page on a sheet of paper. If there is an instruction to correct for cutting variations, the image forming unit 20 changes the print position based on the correction value. <Step S1150 Next page available?> The control unit 30 refers to the job and determines whether there is a next page. If there is a next page (Yes), the process proceeds to step S1020. If there is no next page (No), the process proceeds to step S1160.

[0052] <Step S1160: Next job available?> The control unit 30 refers to the job list and determines whether there is a next job. If there is a next job (Yes), the process proceeds to step S1010. If there is no next job (No), the process proceeds to step S1170. <Step S1170 Printing End> The control unit 30 instructs the image forming unit 20 to end printing, and the printing process S1 in FIG. 6 ends.

[0053] (Paper feed tray switching in the first embodiment) The paper feed tray switching process (step S1040A) in the printing process S1 will now be described with reference to a flowchart of FIG. <Step S2010: Get paper information> The paper management unit 32 acquires paper information. This acquisition may be performed in order, for example, from the first row the first time, the second row the second time, and so on, in the table of FIG.

[0054] <Step S2020 Paper information match?> The paper management unit 32 determines whether the acquired paper information matches the paper information of the paper feed tray before switching. It is desirable to select a paper feed tray that matches paper characteristics such as paper type and basis weight as much as possible in addition to paper size, so that the user can obtain the desired output. Here, a match is determined if the values ​​of specified items match. The specified items are the three items of "size," "paper type," and "basis weight." The specified items can be set by the user. If it matches the one before the switch (Yes), the process proceeds to step S2030. If it does not match (No), the process proceeds to step S2070.

[0055] <Step S2030 Paper tray selection> The paper management unit 32 selects the paper feed tray associated with the paper information that is determined to match as the destination to switch to. <Step S2040 Is the reference value registered?> The paper management unit 32 determines whether a reading reference value is registered in the acquired paper information. If it is registered (Yes), the process ends, and if it is not registered (No), the process proceeds to step S2050. <Step S2050: Obtaining the reference value of the tray before switching> The paper management unit 32 acquires the reading reference value of the paper feed tray before switching.

[0056] <Step S2060: Register as post-switch reference value> The paper management unit 32 registers the acquired reading reference value of the previous paper feed tray as the reading reference value of the next paper feed tray, and ends the process. For example, if the tray 2 in FIG. 5 runs out of paper while job No. 1 in FIG. 3 is being executed, tray 6 is selected and the reading reference value of tray 2 is registered in tray 6. <Step S2070: Are there other paper trays?> The paper management unit 32 checks whether there is another paper feed tray. If there is another paper feed tray (Yes), the process proceeds to step S2010. If there is no other paper feed tray (No), the process ends.

[0057] (Printing process of the second embodiment) The printing process S2 in the image forming apparatus according to the second embodiment will be described. The printing process S2 is different from the printing process S1 in the paper feed tray switching process, and the rest is common. Therefore, the paper feed tray switching process (step S1040B) in the printing process S2 will be described, and other descriptions will be omitted. Further, the process of step S1040B is different from step S1040A when <S2040 Is reference value registered?> is Yes, and the rest is common. Therefore, that case will be described. FIG. 8 is a flowchart illustrating the flow of the paper feed tray switching process in the printing process S2.

[0058] <Step S2040 Is reference value registered?> The paper management unit 32 determines whether a reading reference value is registered in the acquired paper information. If registered (Yes), the process transitions to step S2062. If not registered (No), the process transitions to step S2050. <Step S2062 Is reference value registration date before threshold?> The paper management unit 32 determines whether a predetermined time (for example, 30 days) or more has elapsed since the registration date of the reading reference value of the switching destination paper feed tray. If a predetermined time or more has elapsed (Yes), the process transitions to step S2063. If less than the predetermined time (No), the process transitions to step S2064.

[0059] Since the paper may expand or contract due to changes in environmental conditions (temperature, humidity), or the paper may not be from the same manufacturing lot, it is desirable to discard the reading reference value with an old registration date. For example, if the current date is 2024 / 6 / 17 and switching from tray 1 to tray 5 in FIG. 5 during the execution of job No4 in FIG. 3, the registration date of the reading reference value of tray 5 is 2024 / 4 / 30, which is more than 30 days ago. Therefore, the reading reference value of tray 5 is discarded and updated in the next step S2063.

[0060] <Step S2063 Reference value registration> The control unit 30 executes "reference value registration" for the switching destination paper feed tray, and then ends the process. "Reference value registration" will be separately described with reference to FIG. 9. <Step S2064: Is the reference value difference greater than or equal to the threshold?> The paper management unit 32 determines whether the difference between the read reference values ​​before switching and after switching is a predetermined value (for example, 1%) or more. If it is the predetermined value or more, the process proceeds to step S2063. If it is less than the predetermined value, the process ends.

[0061] If the difference in the reading reference values ​​is large, it is highly likely that the environmental conditions (temperature, humidity) or paper type are different, so it is desirable to discard the reading reference values. For example, if switching from tray 3 to tray 4 in Fig. 5 while job No. 3 in Fig. 3 is being executed, there is a difference of 1% or more in the paper length or width values ​​of the reading reference values ​​for both, so the reading reference value for tray 4 is discarded and updated in the next step S2063. 8, step S2062 and step S2064 may be interchanged. That is, if the answer is Yes in step S2040, the process may proceed to step S2064 first, and if the answer is No in step S2064, the process may proceed to step S2062.

[0062] (Registered standard value) The reference value registration process (step S2063) in the paper feed tray switching process (step S1040B) of the print process S2 will be described below. Fig. 9 is a flowchart illustrating the reference value registration process. <Step S3010: Obtain the reference value registration tray> The control unit 30 acquires the paper feed tray (reference value registration tray) selected as the target for reference value registration. Note that reference value registration may also be executed in response to an instruction from the user via the display unit 60 or the like.

[0063] <Step S3020 Paper Feed> The control unit 30 instructs the paper feed unit 10 to feed paper from the paper feed tray. <Step S3030: Reading Paper Before Image Formation (Generating Reading Reference Values)> The control unit 30 instructs the reading unit 40 to read the fed paper. The reading unit 40 responds to the control unit 30 with the reading result as a read value. For example, the read value is output as the number of pixels in the vertical and horizontal directions of the paper read by a CIS or CCD sensor.

[0064] <Step S3040: Register reading reference value> The control unit 30 notifies the paper management unit 32 of the read value and instructs it to register it as the read reference value for the paper feed tray. At this time, if a paper profile is applied to the paper feed tray, the paper management unit 32 also updates the read reference value of the paper profile. As a result, if the same paper profile is applied to multiple paper feed trays, the new read reference value is reflected in those paper feed trays as well. For example, when a reference value is registered for tray 2 in Figure 5, the paper management unit 32 also updates the reading reference value for tray 7, to which the same paper profile is applied, via the applied paper profile ``For books 1.''

[0065] <Step S3050 Are there other reference value registration trays?> The control unit 30 checks whether there are any other paper feed trays selected as targets for reference value registration. If there are (Yes), the process proceeds to step S3010, and if there are not (No), the process ends.

[0066] (Printing process of the third embodiment) The printing process S3 in the image forming apparatus according to the third embodiment will be described. The printing process S3 differs from the printing process S1 in that a "reference value registration pre-check" is performed after <Step S1010 Job Acquisition>, but the rest is the same. Therefore, only the "reference value registration pre-check" process (Step S1015) will be described, and other explanations will be omitted. Figure 10 is a flowchart illustrating the flow of the printing process S3. <Step S4010: Calculate the number of sheets consumed> The control unit 30 calculates the number of sheets of paper to be consumed from the number of pages of the current job.

[0067] <Step S4020 Paper low?> The control unit 30 acquires the amount of remaining paper from the paper feed unit 10 and compares it with the number of sheets consumed to determine whether there is a shortage. If there is a shortage (Yes), the process proceeds to step S4030, and if there is not a shortage (No), the process ends. Note that if the "tray designation" for the job is automatic, the process proceeds to step S4030 and there is no problem in proceeding with the selection of the paper feed tray to switch to. However, if a paper feed tray is designated in the "tray designation," it is desirable for the control unit 30 to proceed with the process by confirming with the user whether or not to switch the paper feed tray. <Step S4030: Obtain paper information> The control unit 30 instructs the paper management unit 32 to select a tray to switch to when the paper runs out. The paper management unit 32 acquires paper information.

[0068] <Step S4040 Paper information match?> The paper management unit 32 determines whether the paper information acquired from the paper in the switched-to tray matches the paper information of the paper tray before switching. If they match (Yes), the process proceeds to step S4050. If they do not match (No), the process proceeds to step S4070. Here, as in <Step S2020 Paper Information Match?>, it is determined that there is a match when certain items (for example, the three items of "size," "paper type," and "basis weight") match. <Step S4050 Is the reference value registered?> The paper management unit 32 determines whether a reading reference value is registered in the acquired paper settings. If it is registered (Yes), the process ends. If it is not registered (No), the process proceeds to step S4060.

[0069] <Step S4060: Register reference value> The paper management unit 32 executes "reference value registration" for the destination paper feed tray. This "reference value registration" process is the same as <Step S2063 Reference Value Registration> described in the second embodiment. <Step S4070: Are there other paper trays?> The paper management unit 32 checks whether there are other paper feed trays. If there are other paper feed trays (Yes), the process proceeds to step S4030. If there are not (No), the process ends. If a new paper feed tray whose paper information matches the paper information before the switch is not found, the printing process is suspended in <Step S1060 Printing Suspended> until paper is replenished.

[0070] [Control method] The control method according to the embodiment is a method for controlling an image forming apparatus that includes the hardware configuration of the image forming apparatus 1 according to the first embodiment, for example. The control method according to the embodiment includes the steps of a paper feed unit selecting one of a plurality of switchable paper feed trays and feeding paper; a reading unit reading the dimensions of the fed recording medium before image formation and outputting the reading value; a recording medium management unit linking recording medium information, which is information about the recording medium including a reading reference value registered as a standard for the reading value, to the paper feed tray and managing it; when switching the paper feed tray, selecting a paper feed tray that matches a specified item of the recording medium information as the switching destination; and a step of an image forming unit correcting the position of the image on the recording medium based on the amount of change in the reading value relative to the reading reference value and forming the image.

[0071] In the control method according to the embodiment, if the reading reference value is not registered in the paper information of the paper feed tray to which the switch is made, the reading reference value before the switch can be used. In the control method according to the embodiment, even if a reading reference value is registered in the paper information of the paper feed tray to which the switch is made, if the difference between the reading reference value before the switch and the reading reference value after the switch is greater than a predetermined threshold, or if the elapsed time since registration of the reading reference value of the paper feed tray to which the switch is made is greater than a predetermined time, it is also preferable to read the paper fed from the paper feed tray to which the switch is made and output the reading value, and update the reading reference value of the paper feed tray to which the switch is made with that reading value. It is also preferable to predict a paper shortage for the job before starting an image formation job and select a destination paper feed tray in advance, and if a reading reference value is not registered in the paper information of the destination paper feed tray, read the paper fed from the destination paper feed tray, output the reading value, and register the output reading value as the destination reading reference value before starting the job.

[0072] [program] The program according to the embodiment is a program that can be executed by a CPU of an image forming apparatus having the hardware configuration of the image forming apparatus 1 according to the first embodiment, for example, to control the image forming apparatus. The program according to the embodiment causes a computer to execute the following steps: selecting one of a plurality of switchable paper feed trays and feeding paper; reading the dimensions of the fed recording medium before image formation and outputting the reading value; linking and managing recording medium information, which is information about the recording medium including a reading reference value that is registered as a standard for the reading value, to the paper feed tray; selecting, when switching between paper feed trays, a paper feed tray that matches a specified item of the recording medium information; and correcting the position of the image on the recording medium based on the amount of change in the reading value relative to the reading reference value to form the image.

[0073] In the program according to the embodiment, if the reading reference value is not registered in the paper information of the paper feed tray to which the switch is made, the reading reference value before the switch can be used. Even if a reading reference value is registered in the paper information of the paper feed tray to which the switch is made, if the difference between the reading reference value before the switch and the reading reference value after the switch is greater than a predetermined threshold, or if the elapsed time since registration of the reading reference value of the paper feed tray to which the switch is made is greater than a predetermined time, it is also preferable that the program of the embodiment reads the paper fed from the paper feed tray to which the switch is made, outputs the reading value, and updates the reading reference value of the paper feed tray to which the switch is made with that reading value. It is also preferable to predict a paper shortage for the job before starting an image formation job and select a destination paper feed tray in advance, and if a reading reference value is not registered in the paper information of the destination paper feed tray, read the paper fed from the destination paper feed tray, output the reading value, and register the output reading value as the destination reading reference value before starting the job.

[0074] The image forming apparatus may be controlled by a computer that has loaded a program according to the embodiment. The program according to the embodiment can be obtained through an electric communication line and can be recorded on a computer-readable recording medium. [Explanation of symbols]

[0075] 1. Image forming device 10 Paper feed section 12 Paper tray 14 Transport path 20 Image forming unit 30 Control Unit 32 Recording Media Management Department (Paper Management Department) 34 Image correction section 40 Reading unit 45 sensors 50 Central Control Unit 60 Display section 70 Paper output section 72 Paper output tray

Claims

1. a paper feed unit having a plurality of switchable paper feed trays, and feeding paper from one paper feed tray selected from the plurality of paper feed trays; a reading unit that reads the dimensions of the recording medium fed from the paper feed unit before an image is formed thereon and outputs a read value; an image correction unit that calculates a correction value for the position of an image to be formed on the recording medium using the read value; an image forming unit that forms an image on a recording medium based on the correction value; a recording medium management unit that manages recording medium information, which is information about a recording medium including a read reference value that is registered as a reference for the read value, by linking it to the paper feed tray; the recording medium management unit selects, as a switching destination, a paper feed tray among the plurality of paper feed trays that matches a predetermined item of the recording medium information; The image correction unit calculates the correction value based on a change amount of the read value relative to the read reference value.

2. If the reading reference value is not registered in the recording medium information of the switched paper tray, 2. The image forming apparatus according to claim 1, wherein the image correction unit calculates the correction value using a read reference value of the paper feed tray before switching.

3. If the difference in the reading reference value between the paper feed tray to be switched and the paper feed tray before the switch is equal to or greater than a predetermined threshold value, the reading unit reads the recording medium fed from the switched-to paper feed tray and outputs the read value; 2. The image forming apparatus according to claim 1, wherein the recording medium management unit updates the read reference value of the switching destination with the output read value.

4. the paper feed unit predicts a shortage of the recording medium in the job before starting the image formation job and selects in advance a paper feed tray to be switched to; The image forming apparatus according to claim 3 , wherein the recording medium management unit updates the reading reference value before the job starts.

5. Regarding the reading reference value of the paper tray to be switched to, if the elapsed time since registration is more than the specified time, the reading unit reads the recording medium fed from the switched-to paper feed tray and outputs the read value; 2. The image forming apparatus according to claim 1, wherein the recording medium management unit updates the read reference value of the switching destination with the output read value.

6. the paper feed unit predicts a shortage of the recording medium in the job before starting the image formation job and selects in advance a paper feed tray to be switched to; The image forming apparatus according to claim 5 , wherein the recording medium management unit updates the reading reference value before the job starts.

7. before starting an image forming job, predicting a shortage of the recording medium in the job and selecting a paper feed tray to be switched to in advance; If the reading reference value is not registered in the recording medium information of the paper feed tray to which the paper is to be switched, the reading unit reads the recording medium fed from the switched-to paper feed tray and outputs the read value; 2. The image forming apparatus according to claim 1, wherein the recording medium management unit registers the output read value as the read reference value of the switch destination before the job is started.

8. 8. The image forming apparatus according to claim 1, wherein the predetermined items of the recording medium information are the type, basis weight, and size of the recording medium.

9. a step in which a paper feeding unit selects one of a plurality of switchable paper feeding trays and feeds paper; a reading unit reading dimensions of a recording medium before image formation and outputting a read value; a step in which a recording medium management unit manages recording medium information, which is information about the recording medium including a read reference value registered as a reference for the read value, by linking the recording medium information to the paper feed tray; a step of selecting, as a switching destination, the paper feed tray that matches a predetermined item of the recording medium information in the paper feed tray switching; an image forming unit correcting a position of an image on the recording medium based on a change amount of the read value relative to the read reference value, and forming an image; A control method comprising:

10. On the computer, A procedure for selecting one of multiple switchable paper feed trays to feed paper; a step of reading the dimensions of the recording medium before image formation and outputting the read values; a step of managing recording medium information, which is information about the recording medium including a read reference value to be registered as a reference for the read value, by linking it to the paper feed tray; a step of selecting, as a switching destination, the paper feed tray that matches a predetermined item of the recording medium information when switching the paper feed tray; a step of correcting the position of the image on the recording medium based on the amount of change in the read value relative to the read reference value, and forming the image; A program to execute.

Images