Image forming system and printing method

Abstract

To detect a sheet size or a sheet shape with high accuracy.SOLUTION: An image forming system includes: a reading unit 50 including a reading sensor 51 that optically reads a sheet conveyed through a conveyance path 341; and a control unit that controls the reading unit 50. The reading unit 50 is able to execute a plurality of reading modes including at least a first reading mode and a second reading mode different from the first reading mode, and reads the sheet in any one of the reading modes selected according to a print setting. The control unit varies an image formation timing of forming an image on the sheet by an image forming unit between when switching of the reading modes is performed and when the switching of the reading modes is not performed.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an image forming system and a printing method. [Background technology]

[0002] There is a technology in which an image forming device detects the size of a sheet of paper and corrects an image according to the detected size (for example, Patent Document 1). In the image forming device disclosed in Patent Document 1, the size measuring unit is positioned sufficiently upstream of the image forming unit, so that the image position correction set based on the measurement result of the size measuring unit is reflected in the detected sheet of paper.

[0003] Furthermore, in Patent Document 1, a contact image sensor (CIS) that measures the paper width as a size measurement unit detects the positions of the side edges of the paper (the positions of the right edge and the left edge in the conveying direction) to measure the paper width (paragraph 0013). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-238544 A Summary of the Invention [Problem to be solved by the invention]

[0005] In image forming devices, various types of paper are used, for example, dark colored paper other than white paper may be used. In the above-mentioned image forming device, the positions of both side edges of the paper are detected by the CIS, but with colored paper, there is a risk that the edges cannot be detected accurately because sufficient contrast cannot be obtained at the edge positions.

[0006] The present invention has been made in consideration of the above circumstances, and has an object to detect the paper size or shape with high accuracy at an appropriate timing. [Means for solving the problem]

[0007] The above object of the present invention can be achieved by the following means.

[0008] (1) a paper feed section that feeds paper; a conveying section that conveys paper along a conveying path; a reading unit including a reading sensor that optically reads the paper conveyed through the conveying path; an image forming unit that is located downstream of the reading unit in the conveying path and that forms an image on the conveyed paper; A control unit, the reading unit is capable of executing a plurality of reading modes including at least a first reading mode and a second reading mode different from the first reading mode, and reads the paper in one of the reading modes selected in accordance with a print setting; The control unit causes the image forming unit to form an image on the paper at different timings depending on whether the reading mode is switched or not.

[0009] (2) The image forming system according to (1) above, wherein the reading unit executes the reading mode according to the color of the paper to be read.

[0010] (3) The reading unit includes a background unit disposed opposite the reading sensor across the transport path, the background unit having a plurality of background surfaces of different colors that become the background of the paper when reading; The image forming system according to (1) or (2), wherein the switching of the reading mode is switching of the background surface.

[0011] (4) The image forming system according to (3) above, wherein the reading unit switches the background surface depending on the color of the paper to be read.

[0012] (5) the paper feed unit includes a plurality of paper feed trays for storing paper; The image forming system according to (1) or (2) above, wherein a different reading mode is selected depending on switching of the paper feed tray into which the paper to be read is fed.

[0013] (6) The image forming system described in (1) or (2) above, wherein the control unit delays the timing of image formation on the paper to be read by the image forming unit in the second reading mode based on the switching time required to switch from the first reading mode to the second reading mode.

[0014] (7) The paper feed unit includes a plurality of paper feed trays for storing paper, A different reading mode is selected in response to switching of the paper feed tray into which the paper to be read is fed, The image forming system described in (6) above, wherein when transporting multiple sheets of paper continuously, and the previous and next sheets are fed from different paper feed trays, the control unit compares the delay time in the timing at which the paper is transported to the reading area of ​​the reading unit due to the change in paper feed tray with the switching time required to switch the reading mode, and if the delay time is longer than the switching time, does not delay the timing of image formation on the next sheet of paper.

[0015] (8) When multiple sheets of paper are fed continuously, the distance between the previous and next sheets is set differently depending on the paper size. The control unit compares the paper interval time corresponding to the paper interval with the switching time required to switch the reading mode, and if the paper interval time is longer than the switching time, does not delay the timing of image formation on the next paper.The image forming system described in (6) above.

[0016] (9) In the image forming system described in (6) above, when multiple sheets of paper are transported continuously, if a stabilization process is performed in the image forming unit between the previous sheet and the next sheet of paper, the control unit does not perform a process to delay the timing of image formation on the next sheet of paper in response to the switching of the reading mode, but switches the reading mode during the period in which the stabilization process is being performed.

[0017] (10) The image forming system according to (1) or (2), wherein the control unit selects a reading mode to be executed based on print settings of a print job.

[0018] (11) The image forming system described in (1) or (2) above, wherein when multiple sheets of paper are transported continuously, if the previous sheet of paper is read in the first reading mode, and the next sheet of paper can be read in both the first reading mode and the second reading mode, the control unit reads the next sheet of paper in the same first reading mode as the previous sheet of paper.

[0019] (12) In the image forming system described in (1) or (2) above, when multiple sheets of paper are transported continuously, if the previous sheet is not being read, the control unit starts switching the reading mode for the next sheet of paper while the previous sheet is transporting through the reading area of ​​the reading unit.

[0020] (13) a correction value calculation unit that calculates a paper position correction value based on read data obtained by reading the paper with the reading unit; The image forming system described in (1) or (2) above is provided with a print control unit that adjusts the image forming position on at least one of the first and second sides of the read paper based on the paper position correction value calculated by the correction value calculation unit.

[0021] (14) a paper feed unit that feeds paper; a conveying section that conveys paper along a conveying path; a reading unit including a reading sensor that optically reads the paper conveyed through the conveying path; an image forming unit that forms an image on the transported paper downstream of the reading unit in the transport path, the image forming system including: The reading unit is capable of executing a plurality of reading modes including at least a first reading mode and a second reading mode different from the first reading mode, and a step (a) of selecting one of the reading modes in accordance with a print setting; (b) reading the paper in the selected reading mode; (c) causing the image forming unit to form an image on the paper at different timings depending on whether the reading mode is switched or not; and (d) forming an image on the paper at the image formation timing.

[0022] (15) The printing method according to (14) above, wherein in the step (a), the reading mode is selected according to the color of the paper to be read. Effect of the Invention

[0023] The image forming system according to the present invention includes a reading unit having a reading sensor that optically reads paper conveyed along a conveying path, an image forming unit that forms an image on the conveyed paper downstream of the reading unit on the conveying path, and a control unit, the reading unit is capable of executing a plurality of reading modes including at least a first reading mode and a second reading mode different from the first reading mode, and reads the paper in one of the reading modes selected according to print settings, and the control unit causes the image forming unit to form an image on the paper at different timings depending on whether the reading mode is switched or not. In this way, the paper size or shape can be detected accurately at the appropriate timing. [Brief description of the drawings]

[0024] [Figure 1] 1 is a diagram showing a schematic configuration of an image forming apparatus including a reading device according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a block diagram showing a hardware configuration of the image forming system. [Diagram 3] 2 is a schematic diagram showing a main configuration of a reading unit in the first embodiment. FIG. [Figure 4] FIG. 2 is a schematic diagram showing a main configuration of a reading unit. [Diagram 5]13 is a table for explaining the use conditions of each surface of the background portion. [Figure 6] 13 is a table for explaining the use conditions of each surface of the background portion. [Figure 7] 6 is a flowchart showing a background plane switching process and a printing process in the first embodiment. [Figure 8] 8 is a subroutine flowchart showing the process of step S120 in FIG. 7. [Figure 9] 2 is an example of a print job. [Figure 10] 11 is an example of a table showing a switching time required to switch from a reading mode for a previous sheet to a reading mode for a next sheet. [Figure 11] 13 is a table for explaining the use conditions of each surface of the background part in the second embodiment. [Figure 12] 13 is a table for explaining the use conditions of each surface of the background part in the second embodiment. [Figure 13] 8 is a subroutine flowchart showing the process of step S120 of FIG. 7 in the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, an embodiment of the present invention will be described with reference to the attached drawings. However, the scope of the present invention is not limited to the disclosed embodiment. In the description of the drawings, the same elements are given the same reference numerals, and duplicated description will be omitted. Also, the dimensional ratios of the drawings are exaggerated for convenience of description, and may differ from the actual ratios. In the drawings, the up-down direction (vertical direction) is the Z direction, the front and back directions of the image forming system or the reading device are the Y direction, and the direction perpendicular to these Y and Z directions is the X direction. The X direction is also called the paper transport direction. The Y direction is also called the width direction. In this embodiment, the paper includes printing paper (hereinafter simply called paper) and various films.

[0026] Fig. 1 is a diagram showing a schematic configuration of an image forming system 1000 including a reading device 30 according to this embodiment. Fig. 2 is a block diagram showing a hardware configuration of the image forming system 1000. As shown in Fig. 1, the image forming system 1000 includes an image forming device 10, a paper feeder 20, a reading device 30, and a post-processing device 40, which are mechanically and electrically connected to each other.

[0027] (Image forming apparatus 10) The image forming apparatus 10 forms an image on a sheet 90 that is fed from a sheet feeding device 20 on the upstream side and sent via a reading device 30. The image forming apparatus 10 also forms an image on a sheet 90 that is fed from a sheet feeding section of the image forming apparatus 10 itself.

[0028] The image forming apparatus 10 includes a control unit 11, a storage unit 12, an image forming unit 13, a conveying unit 14, a paper feeding unit 15, an operation panel 18, a communication unit 19, etc. These are connected to each other via signal lines such as a bus for exchanging signals. Note that in Fig. 2, the signal lines connecting some of the components of the image forming apparatus 10, such as the storage unit 12 and the operation panel 18, are omitted (the connection to the control unit 31 of the reading device 30 described below, etc. is also omitted).

[0029] (Control unit 11) The control unit 11 is composed of a CPU, a ROM, a RAM, etc., and executes various processes by executing programs stored in the ROM or in a storage unit 12 described below, and controls each unit of the device and performs various arithmetic processes according to the programs. The control unit 11 functions as a print control unit 111, a reading device control unit 112, an other device control unit 113, and a correction value calculation unit 114. The functions of these sub-control units 111 to 114 will be described later.

[0030] (Storage unit 12) The storage unit 12 is composed of an auxiliary storage unit such as a hard disk that stores various programs and various data in advance. The storage unit 12 also stores information on the paper stored in each paper feed tray (trays 155, 255, 256, etc., described later) in association with the paper feed tray. The paper information includes information on the brand, size (paper width, paper length), paper color, basis weight, and paper type (gloss coated paper, matte coated paper, plain paper, high-quality paper, rough paper, etc.). The storage unit 12 may also store a paper brand, a determination model (determination model algorithm) used to determine the control parameters, and a paper profile. The storage unit 12 also stores a switching time required to switch the background unit 56, a paper interval time (paper interval) associated with switching to a paper feed tray (paper feed trays 255, 256, etc., described later), and a paper interval time (paper interval) for each paper size. Here, the paper interval time refers to the interval (measured in conveying time) from the rear end of the previous paper 90 to the front end of the next paper 90. Also, the memory unit 12 has set therein conditions for executing a stabilization process of the image forming unit 13. For example, the stabilization process is executed when a predetermined event occurs, such as the main body being turned on, or every predetermined number of prints (for example, every 1,000 sheets).

[0031] (Image forming unit 13) The image forming unit 13 forms an image, for example, by an electrophotographic method. The image forming unit 13 includes writing units (laser exposure units) corresponding to the basic colors of Y (yellow), M (magenta), C (cyan), and K (black), a photosensitive drum, and a developing unit that contains a two-component developer consisting of toner and carrier of each color. The image forming unit 13 further includes an intermediate transfer belt, a secondary transfer unit, and a fixing unit. The toner images formed on the photosensitive drum by the developing units of each color are superimposed on the intermediate transfer belt, and are transferred to the paper 90 conveyed in the secondary transfer unit. The toner image on the paper 90 is fixed onto the paper 90 by being heated and pressed in the fixing unit downstream.

[0032] A density sensor that optically detects the density of the toner patch formed on the intermediate transfer belt is disposed in the image forming unit 13. In the stabilization process, a plurality of patch images with different colors and gradations (densities) are printed on the intermediate transfer belt based on the evaluation chart data stored in the storage unit 12, the reflection density of these images is detected by the density sensor, and the image forming conditions are adjusted based on the obtained data.

[0033] (Transport section 14, Paper feed section 15) The transport unit 14 includes transport paths 141, 142, etc. The paper feed unit 15 includes a plurality of paper feed trays 155. The transport path 141 includes a plurality of transport roller pairs provided along the transport path, and a drive motor (not shown) that drives these transport roller pairs. The paper feed unit 15 includes a feed roller that feeds the topmost sheet of paper 90 stacked and placed in the paper feed tray 155, and sends the sheets 90 in the paper feed tray one by one to the downstream transport path. A transport path 341 of the reading device 30 is connected to the upstream side of the transport path 141.

[0034] The conveying section 14 conveys the paper 90 fed from the paper feed tray 155 or the like. The paper 90 conveyed along the conveying path 141 has an image formed on it by the image forming section 13, and is then discharged onto the paper output tray 41 via the subsequent post-processing device 40. When performing double-sided printing in which an image is also formed on the back side (second side) of the paper 90, the paper 90 with an image formed on one side is conveyed to a conveying path 142 for double-sided image formation located at the bottom of the device main body. The paper 90 conveyed to this conveying path 142 is turned over on a switchback path, and then merges with the conveying path 141 for one side, where an image is again formed on the other side of the paper 90 by the image forming section 13.

[0035] (Operation panel 18, etc.) Operation panel 18 includes a touch panel, numeric keypad, start button, stop button, etc. Operation panel 18 displays the status of image forming apparatus 10 or image forming system 1000, and is used for inputting various settings and instructions from the user. The user can set the type of paper loaded in paper feed trays 155, 255, etc., and paper color information through the setting screen of operation panel 18 (see FIG. 6 described later). In addition, the user can set the following through the setting screen of operation panel 18 or the setting screen of a print setting application running on a PC (personal computer) communicatively connected to image forming system 1000 (hereinafter referred to as operation panel, etc.). (1) Paper size to be used as print settings, (2) Paper color information, and (3) Setting of paper image position correction, such as enable / disable, etc. In the following, the paper size and color information of the paper are also referred to as paper attribute information.

[0036] The communication unit 19 is an interface for communicating with a PC or other devices 20, 30, etc.

[0037] (Sub-control units 111 to 114) When a print job is input, the print control unit 111 executes the print job based on the print job setting information of the input print job. The print job is input based on instructions sent from the operation panel 18 or an external terminal such as a network-connected PC operated by a user.

[0038] The print control unit 111 controls the transport unit 14 (including drive motors for transport paths 141, 142, the fixing unit, etc.) and the paper feed unit 15 to control the feeding and transporting of the paper 90. The print control unit 111 also instructs the reading device control unit 112 to read the paper 90 before image formation (read instruction) according to the print job setting (enablement of image position correction). The print control unit 111 also calculates the time required to switch the background surface (see FIG. 4 described later) between the reading modes (hereinafter referred to as "switching time"). This switching time may be calculated according to the positional relationship (rotation amount of 90 degrees or 270 degrees) between the current background surface (background surface 1, 2, paper passing surface) and the background surface to be switched and the moving speed (rotation speed). Also, a table describing the previous and next background surfaces and their switching times stored in advance in the storage unit 12 may be referenced (for example, see FIG. 10 described later). Alternatively, the switching time may be obtained by inquiring of the control unit 31 of the reading device 30 via the reading device control unit 112.

[0039] In addition, the print control unit 111 compares the switching time with the current paper interval, and if the switching time is longer than the paper interval, controls the image forming unit 13 and / or the paper feeding unit 255, etc. to extend the image formation timing or the paper interval.

[0040] In addition, the print control unit 111 controls the image forming unit 13, controls the image formation timing according to the image formation conditions and the paper position based on the paper position correction value calculated by the correction value calculation unit 114 described below, and adjusts the vertical and horizontal magnification (hereinafter referred to as position correction control).

[0041] As described below, the position correction control is performed on at least either the first surface (front side) or the second surface (back side) depending on the placement position of at least the reading unit 50. The placement condition of the reading unit 50 varies depending on the conveying path length or conveying speed of the reading device 30 itself, or if another device is connected between the reading device 30 and the image forming apparatus 10. (1) Possible placement conditions for both the first and second sides For example, if the placement condition of the reading unit 50 is such that it is sufficiently upstream of the image forming unit 13 (similar to, for example, JP 2014-238544 A) and the placement position allows for image correction timing, position correction control is performed on the paper 90 on which reading has been performed. Specifically, if the reading unit 50 is disposed in a positional relationship such that (b) comes after (a) below, position correction control is performed when forming an image on the first and / or second side of the paper 90 that has been read: (a) the timing at which preparation for image formation reflecting position correction control is completed from image data (hereinafter referred to as read data) obtained by reading the paper 90 by the reading unit 50 of the reading device 30, and (b) the timing at which image formation on the paper 90 begins. (2) Placement conditions possible only on the second side Furthermore, if the placement condition of the reading device 30 is such that the image correction timing is not possible, image formation is performed that reflects position correction control when forming an image on the second side (reverse side) of the read paper 90 during double-sided image formation in order to align the image registration on the front and back sides.

[0042] The reading device control unit 112 controls the reading device 30 in response to an execution instruction request (reading instruction) from the print control unit 111. In response to the execution instruction request, the reading device 30 executes measurement of paper characteristics using the reading unit 50 and various other sensors included in the reading device 30. Furthermore, when the reading device 30 reads the paper 90, the reading device control unit 112 acquires the read data generated by the reading device 30.

[0043] The other device control unit 113 controls the sheet feeding device 20 and the post-processing device 40. Specifically, the other device control unit 113 communicates with the sheet feeding device 20 to transmit and receive information on the sheet feeding tray to be used, the timing of sheet transport, etc. Specifically, the other device control unit 113 transmits to the post-processing device 40 the timing of sheet transport, setting information for post-processing of the sheets to be transported, etc.

[0044] The correction value calculation unit 114 acquires read data obtained by reading the paper 90 before image formation from the reading device control unit 112, and detects the length and shape characteristics of each side (length and width) of the paper 90 from the acquired read data (hereinafter, the detected characteristics are also simply referred to as "paper size"). The correction value calculation unit 114 calculates an image position correction value from the difference between the detected paper size and the paper size in the print settings. The calculated image position correction value is sent to the print control unit 111. As described above, the print control unit 11 performs position correction control to match the paper position according to this image position correction value.

[0045] (Paper feeder 20) 1 and 2, sheet feeding device 20 includes a conveying unit 24 and a sheet feeding unit 25. In addition to conveying unit 24 and sheet feeding unit 25, sheet feeding device 20 also includes a control unit, a storage unit, and a communication unit (none of which are shown), which are connected to each other via signal lines such as a bus for exchanging signals.

[0046] The paper feed unit 25 includes a plurality of paper feed trays 255 and a manual feed tray 256. The paper feed trays 255 are automatically numbered from tray 1 to tray n based on a predetermined rule. The transport unit 24 and the paper feed unit 25 have the same functions as the transport unit 14 and the paper feed unit 15, and feed paper 90 placed on the paper feed tray 255 or the like one sheet at a time and transport it to the transport path 241. The transport path 241 is connected to the subsequent transport path 341. The paper 90 fed from the paper feed tray 245 or the like and transported on the transport path 241 is transported to the downstream reading device 30, where the paper characteristics such as the paper size are measured, and an image is formed on the paper by the image forming device 10 further downstream.

[0047] (Post-processing device 40) The post-processing device 40 performs post-processing on the paper 90 sent from the image forming device 10 and discharges the paper 90 according to the settings of the print job. The post-processing device 40 includes paper output trays 41 and 42, a post-processing unit 43, and a conveying path 441. The post-processing device 40 also includes a control unit, a storage unit, a conveying unit, and a communication unit (none of which are shown), which are connected to each other via signal lines such as a bus for exchanging signals. The paper output trays 41 and 42 are selected according to the settings of the print job. The conveying path 441 is connected to the conveying path 141 on the upstream side. The post-processing unit 43 performs at least one of post-processing, including stapling, punching, cutting, folding, and bookbinding, on the paper 90 on which an image has been formed.

[0048] (Reader 30) Next, the reading device 30 will be described. As shown in Fig. 2, the reading device 30 includes a control unit 31, a storage unit 32, a conveying unit 34, a communication unit 39, a reading unit 50, etc. The control unit 31, the storage unit 32, the conveying unit 34, and the communication unit 39 each have the same hardware configuration as the control unit 11, the storage unit 12, the conveying unit 14, and the communication unit 19 of the image forming apparatus 10 described above, and therefore the description thereof will be omitted.

[0049] (Reading unit 50) The outline of the reading unit 50 will be described below with reference to FIG. 3 to FIG. 6. FIG. 3 and FIG. 4 are schematic diagrams showing the main configuration of the reading unit 50. FIG. 3(a) is a top view, and FIG. 3(b) is a side view. The reading unit 50 includes a reading sensor 51, a background unit 56, and a switching mechanism 57. The reading sensor 51 is a one-dimensional line sensor having a plurality of photoelectric conversion elements arranged in the Y direction, and reads a one-dimensional image. The reading sensor 51 also has optical elements such as light-emitting elements and lens arrays arranged along the row of the photoelectric conversion elements. During reading, the light-emitting elements irradiate uniform light in the extension direction of the row toward the paper 90 on the conveying path 341. The reading unit 50 reads the paper 90, and read data corresponding to one sheet of paper is generated.

[0050] The background portion 56 has a polygonal prism shape with its axis extending in the Y direction. In the example shown in FIG. 4 etc., the background portion 56 has a quadrangular prism shape with four faces 561 to 564. The switching mechanism 57 is composed of a drive source and a rotation mechanism such as gears, and switches the background face facing the reading sensor 51 by controlling the rotation position of the background portion 56. For example, the switching mechanism 57 has a servo motor or a stepping motor, and rotates the background portion 56 around the rotation axis in the clockwise direction in FIG. 4 by a predetermined angle (an integer multiple of 90 degrees) and stops it at that position.

[0051] 3(b) and 4, the background portion 56 is disposed facing the reading sensor 51 across the transport path 341. The background portion 56 is disposed in a cut-out portion of a lower guide plate that constitutes the transport path 341. The background portion 56 has four surfaces 561 to 564, and the surface that faces the reading sensor 51 is switched by a switching mechanism 57.

[0052] The configuration of the background section 56 is not limited to the example shown in FIG. 4 and may be other configurations. For example, four faces are arranged in the X direction on a plate-like background section 56. Then, the background section 56 is slid a predetermined amount back and forth in the X direction by the switching mechanism 57 to switch the face facing the reading sensor 51. As another example, the background section 56 may be configured as a device that can electrically switch the density of the display surface, such as electronic paper. In this case, the density (brightness) of the face facing the reading sensor 51 is switched by electrical control.

[0053] 3(a), the reading area of ​​the reading sensor 51 in the Y direction ranges from y0 to y100, which is wider than the maximum paper width of the paper 90 that can be transported in the image forming system 1000. In addition, in the Y direction, the center c1 of the transport of the paper 90 and the center c1 of the reading area of ​​the reading sensor 51 are aligned.

[0054] (Background surface 1, 2, paper passing surface, etc.) 5 and 6 are tables for explaining the use conditions of the surfaces 561 to 564 of the background portion 56. These tables are stored in advance in the storage unit 12 or the storage unit 32. Background surfaces 1 and 2 (surfaces 561 and 562) are surfaces that are used when the reading setting in the reading unit 50 is valid. In the following, reading using background surface 1 may be referred to as reading mode 1, and reading using background surface 2 may be referred to as reading mode 2 (one of reading modes 1 and 2 corresponds to the first reading mode, and the other corresponds to the second reading mode).

[0055] Surface 561 is black or a color whose brightness is equal to or less than a predetermined value (for example, L* in the CIELAB color space is equal to or less than 20). Surface 561 is a first background surface (hereinafter also referred to as "background surface 1") that becomes the background of paper 90 when read by reading sensor 51. As shown in Figs. 5 and 6, background surface 1 is used when the color information of paper 90 to be read is included in the first group and is a light color whose brightness difference with surface 561 is greater than or equal to a predetermined value.

[0056] Surface 562 is white or a color whose luminosity is equal to or greater than a predetermined value (for example, L* in the CIELAB color space is equal to or greater than 70). Surface 562 is a second background surface (hereinafter also referred to as "background surface 2") that becomes the background of paper 90 when read by reading sensor 51. As shown in Figs. 5 and 6, background surface 2 is used when the color information of paper 90 to be read is included in the second group and is a dark color whose luminosity difference with surface 562 is greater than or equal to a predetermined value.

[0057] The surface 563 is a calibration surface used for calibration of the reading sensor 51, which is performed periodically at a predetermined timing of the reading sensor 51. For example, the surface 563 is configured to have a white color within a specified range, and is used for adjusting the white balance and white level.

[0058] Surface 564 is used when reading is not performed (reading setting is invalid) and functions as a paper passing surface that covers the cutout portion of the lower guide plate of conveying path 341 when paper is passed.

[0059] (Background surface switching and printing) Next, with reference to FIGS. 7 and 8, image formation timing control accompanying background screen switching processing executed by the image forming system 1000 according to the first embodiment and printing processing will be described. FIG.

[0060] FIG. 7 is a flowchart showing the background surface switching process executed by the reading device 30 and the printing process executed by the image forming system 1000. FIG. 8 is a subroutine flowchart showing the process of step S12 in FIG. 7. FIG. 9 is an example of a print job to be executed, where the table in FIG. 9(a) shows a job list, and FIG. 9(b) is a table showing detailed information of job 1 in the job list. The print jobs in the job list are performed consecutively in order starting from job 1. In each job, the image forming system 1000 continuously transports multiple sheets of paper 90 according to the print settings, continuously reads images (according to the image position correction settings), and continuously forms images.

[0061] (Step S110) The print control unit 111 of the control unit 11 reads the top print job in the print job reservation list. In the example shown in Fig. 9, the top job 1 is read. The print job includes print settings and print data (original image data). As shown in Fig. 9, the print settings include at least the paper color (paper attribute information) for each page, and enable / disable settings for image position correction for each print job or each page.

[0062] (Step S115) The print control unit 111 acquires the page settings from the print settings of the currently executed print job.

[0063] (Step S120) The print control unit 111 performs a process of selecting a reading mode based on the print settings or page settings. This process will be described with reference to the subroutine flowchart of FIG.

[0064] (Step S121) The print control unit 111 refers to the print settings or page settings and determines whether image position correction is enabled. If it is set to disabled, the print control unit 111 proceeds to step S122, and if it is set to enabled, the print control unit 111 proceeds to step S123. In the example of job 1 in FIG. 9, image position correction is set to "enabled."

[0065] (Step S122) The print control unit 111 selects a mode other than the reading mode. In this case, the passing side (side 564) is selected.

[0066] (Step S123) The print control unit 111 acquires the paper color (paper information) in the print settings, and also refers to the table in Fig. 6 to determine whether this paper color is group 1 (light color) or group 2 (dark color). If it is group 1, the print control unit 111 advances the process to step S124, and if it is not group 1 (if it is group 2), the process advances to step S125.

[0067] (Step S124) The print control unit 111 selects reading mode 1. In this case, background surface 1 (black) (surface 561) is selected. For example, in the example of job 1 in FIG. 9B, in subjob 1-2, pages 3 to 33 are white paper color (group 1), so background surface 1 (black) is selected.

[0068] (Step S125) The print control unit 111 selects reading mode 2. In this case, background surface 2 (white) (surface 562) is selected. For example, in the example of job 1 in FIG. 9(b), since pages 34 and 35 in subjob 1-3 have a gray paper color (group 2), background surface 2 (white) is selected, which corresponds to reading mode 2 selected in response to switching from paper feed tray 1 to paper feed tray 4. With this, the print control unit 111 ends the processing in FIG. 8 and returns to the processing from step S130 in FIG. 7 onward.

[0069] (Step S130) The print control unit 111 acquires setting information of the current reading mode (background surface) from the reading device control unit 112, and determines whether the current reading mode is different from the reading mode selected in step S120 and whether the reading mode will be switched. If the reading mode is the same between the previous and next consecutive sheets, the print control unit 111 advances the process to step S150, and if the reading mode will be switched, the process advances to step S135.

[0070] (Step S135) The print control unit 111 calculates the switching time of the background surface between the reading modes. FIG. 10 is an example of a table showing the switching time required to switch from the reading mode of the previous paper to the reading mode of the next paper. The switching time from reading mode 1 to reading mode 2 is time 1 (for example, 0.5 sec). The switching time from reading mode 2 to reading mode 1 is time 3 (for example, 1.0 sec), which is longer than time 1. Also, when the previous paper is in a mode other than the reading mode (paper passing side), the switching time is substantially zero because the reading mode of the next paper can be switched to while the previous paper (one or several sheets) is being transported (passing) through the reading unit 50 (particularly the reading area).

[0071] (Step S140) The print control unit 111 controls the control unit 31 through the reading device control unit 112 to switch to the reading mode (background side) selected in step S120. For example, if a mode other than the reading mode (paper passing side) is selected in step S122, the mode is switched to the paper passing side, and if reading mode 1 (background side 1) is selected in step S124, the mode is switched to background side 1.

[0072] (Step S145) The print control unit 111 waits for image formation preparation during the switching time required to switch the reading mode. That is, the print control unit 111 delays the image formation timing during the switching time. The delay delays the feed timing of the paper (next paper) and also delays the image formation start timing (write timing) of this paper 90.

[0073] Incidentally, the print control unit 111 does not have to delay the image formation timing exceptionally in the following cases. (1) When the switching time is less than the paper interval time. The paper interval is set differently depending on the paper size. For example, it is short for A4, A3, and letter, and long for other sizes. It is even longer for non-standard size paper (non-JIS standard). Therefore, when the paper interval time according to the paper size is longer than the switching time, the process (wait) of step S145 is not necessary. (2) When switching time < feed tray change time. When using different feed trays for the previous and next sheets, a delay occurs that lengthens the time between sheets before and after the feed tray change due to the positional relationship of the feed tray being changed (feed tray change time). The distance to a specific position on the transport path (e.g., image formation position, registration roller position, etc.) differs depending on the feed tray. For example, consider the following (2a) and (2b). (2a) When switching to a later paper feed tray after detecting that the previous paper feed tray has run out of paper. (2b) When the distance to the paper feed tray after switching is longer than that of the previous paper feed tray (i.e., when switching to a paper feed tray located further upstream). In this case, the difference in the transport distance between the two paper feed trays will result in a longer distance between the last sheet from the paper feed tray before the switch and the first sheet from the paper feed tray after the switch (the changeover time will be longer). (3) When image stabilization processing is performed between the previous sheet and the next sheet, in this case, the time required for the image stabilization processing is sufficiently longer than the switching time, and therefore the processing (waiting) of step S145 is not required.

[0074] (Step S150) The print control unit 111 reads out the print data of the specified page based on the print settings, and transmits an instruction to the image forming unit 13 to prepare for image formation on the next sheet 90 .

[0075] (Step S160) The print control unit 111 transmits an instruction to the paper feed unit 25 of the paper feed device 20, via the other device control unit 113, to start feeding the next paper 90 from the paper feed tray 255 specified according to the print settings. The paper feed unit 25 feeds the paper 90 from the specified paper feed tray 255 and conveys it along the conveyance path 241. For example, in the case of the example of subjob 1-2 of job 1 in FIG. 9, the paper 90 is fed from tray 1.

[0076] (Step S170) The print control unit 111 refers to the print settings and determines whether image position correction is enabled. If it is set to disabled, the print control unit 111 proceeds to step S220, and if it is set to enabled, the print control unit 111 proceeds to step S180. In the example of job 1 in FIG. 9, image position correction is set to "enabled."

[0077] (Step S180) The print control unit 111 instructs the reading device 30 to read the paper 90 before image formation through the reading device control unit 112. The reading unit 50 reads the designated paper 90 in accordance with the timing at which the paper 90 is transported to the reading area of ​​the transport path 341, and generates read data (image data).

[0078] (Step S210) The reading device control unit 112 acquires the read data generated by the reading in step 21 from the reading device 30 and temporarily stores it in the storage unit 12. Then, the reading device control unit 112 notifies the correction value calculation unit 114 of this. The correction value calculation unit 114 recognizes the end of the paper 90 from the read data and recognizes the lengths and shapes of the four sides of the paper 90. In this case, when reading in step S180, the background surface that serves as the background of the paper 90 when reading and that is arranged opposite the reading sensor 51 (reading sensor) is set to a background surface of a color that has a high contrast with the paper color of the paper 90. Therefore, the correction value calculation unit 114 can accurately recognize the end of the paper 90 from the read data.

[0079] The correction value calculation unit 114 recognizes the paper size from the recognized lengths or shapes of the four sides, and calculates an image position correction value from the difference between the recognized paper size and the paper size in the print settings.

[0080] The correction value calculation unit 114 notifies the print control unit 111 of the calculated image position correction value through the reading device control unit 112. In job 1 shown in Fig. 9, the print control unit 111 uses it as a correction value for the image formation position on the back side (second surface) to match the image registration on the front and back sides (first and second surfaces). The print control unit 111 notifies the image forming unit 13 of the image formation position correction value and sets it.

[0081] (Step S220) The print control unit 111 transmits an instruction to form an image on the next sheet of paper 90 to the image forming unit 13. The image forming unit 13 forms an image on the sheet of paper using the instructed print data. When forming this image, the image position of at least one of the first surface and the second surface is finely adjusted based on the image position correction value.

[0082] (Step S230) The print control unit 111 checks the print settings, and if there is a next page in the print job being executed, returns the process to step S150 and repeats the subsequent processes. On the other hand, if there is no next page, the process proceeds to step S240.

[0083] (Step S240) The print control unit 111 checks the print job reservation list, and if there is a next print job, returns the process to step S110 and repeats the subsequent processes. On the other hand, if there is no next print job, the operation of the device is stopped and the process is terminated (END).

[0084] In this way, the image forming system according to the present embodiment includes a reading unit equipped with a reading sensor that optically reads paper conveyed along a conveying path, the reading unit is capable of executing a plurality of reading modes including at least a first reading mode and a second reading mode different from the first reading mode, and reads the paper in one of the reading modes selected according to print settings, and the control unit causes the image forming unit to form an image on the paper at different timings depending on whether the reading mode is switched or not. With this configuration, reading is performed at an appropriate timing, and the edge position can be accurately detected based on the obtained read data, which in turn allows the paper shape to be detected with high precision.

[0085] Second embodiment Next, an image forming system 1000 according to the second embodiment will be described with reference to Figs. 11 to 13. Figs. 11 and 12 are tables for explaining the conditions of use of each surface of the background part in the second embodiment. In the first embodiment, the paper is classified into two types, groups 1 and 2, according to the color of the paper (see Fig. 6). In the second embodiment, the paper is further classified into three types, including group 3 of intermediate colors, as shown in Fig. 12. Also, as shown in Fig. 11, with intermediate-colored paper in group 3, a certain degree of contrast (brightness difference) can be ensured with respect to both background surfaces 1 and 2, so that sufficient reading accuracy can be ensured regardless of whether background surface 1 or 2 is used for reading.

[0086] Fig. 13 is a subroutine flowchart showing the process of step S120 in Fig. 7 in the second embodiment. The other processes in Fig. 7 other than the processes shown in Fig. 13 are the same as those in the first embodiment, and therefore description thereof will be omitted.

[0087] (Step S301) The process here is the same as step S121 in Fig. 8. The print control unit 111 refers to the print settings or page settings, determines whether image position correction is enabled or disabled, and proceeds to step S303 if enabled, or proceeds to step S302 if disabled.

[0088] (Step S302) The print control unit 111 selects a mode other than the reading mode. In this case, the passing side (side 564) is selected.

[0089] (Step S303) The print control unit 111 acquires the paper color (paper information) in the print settings, and also refers to the table in Fig. 11 to determine whether this paper color is group 1 (light color), group 2 (dark color), or group 3 (medium color). If it is group 1, the print control unit 111 advances the process to step S304, if it is group 2, the process advances to step S305, and if it is group 3, the process advances to step S306.

[0090] (Step S304) The print control unit 111 selects the reading mode 1. In this case, the background plane 1 (black) (plane 561) is selected.

[0091] (Step S305) The print control unit 111 selects the reading mode 2. In this case, the background surface 2 (white) (surface 562) is selected.

[0092] (Step S306) The print control unit 111 determines whether the current paper (i.e., the previous paper) is in reading mode 1 or 2, and whether the current setting is set to background surface 1 or 2. If the previous paper is in reading mode 1 or reading mode 2, the print control unit 111 advances the process to step S307, and if the previous paper is set to a mode other than reading mode (i.e., the paper passing side), the print control unit 111 advances the process to step S304. In step S304, reading mode 1 (background surface 1) is selected. Note that the process here may also proceed to step S305. In this selection, the print control unit 111 may select the mode with the shorter switching time. For example, since the current setting is the paper passing side and switching to background surface 1 takes a shorter switching time (the rotation angle is small at 90 degrees), the print control unit 1 selects reading mode 1 using background surface 1.

[0093] (Step S307) The print control unit 111 selects the same reading mode as the reading mode set for the previous sheet of paper, i.e., the reading mode is not changed from that of the previous sheet of paper.

[0094] In this way, in the second embodiment, when consecutive sheets are conveyed, if the sheet information of the next sheet is the third group (intermediate color) and can be read in both the first and second reading modes, the next sheet is read in the same first reading mode as the previous sheet. This prevents the reading mode from being switched between the previous sheet and the next sheet, and prevents changes in the image formation timing, thereby improving productivity.

[0095] The above-described configuration of the reading device 30 and the image forming system 1000 equipped with the same are merely the main configurations described in the description of the features of the above embodiment, and are not limited to the above configurations and may be modified in various ways within the scope of the claims. Furthermore, configurations equipped in general image forming devices are not excluded.

[0096] 7 and 12, a case where a single print job uses paper of a common color and size is described as an example, but this is not limited to this. For example, if a single print job is a job that uses a mixture of colored paper, the processing from step S120 onward may be performed for each page or for each page where the color of paper changes.

[0097] Also, the color information of the paper is set by the user via the operation panel 18 or the like in the above example, but is not limited to this. As another example, a detection sensor that detects color or density (brightness) may be disposed in the paper feed unit 25 or the transport path 241, 341 from the paper feed tray 255 to the reading unit 50, and the control unit 11 may select the background surface based on the detection value of this detection sensor.

[0098] In addition, the means and methods for performing various processes in the reading device 30 and the image forming system 1000 according to the above-mentioned embodiment can be realized by either a dedicated hardware circuit or a programmed computer. The above-mentioned program may be provided by a computer-readable recording medium such as a USB memory or a DVD (Digital Versatile Disc)-ROM, or may be provided online via a network such as the Internet. In this case, the program recorded in the computer-readable recording medium is usually transferred to and stored in a storage unit such as a hard disk. In addition, the above-mentioned program may be provided as a standalone application software, or may be incorporated into the software of the device as one of its functions. [Explanation of symbols]

[0099] 1000 Image forming system 10 Image forming device 11 Control section 111 Printing control unit 112 Reading device control unit 113 Other device control section 114 Correction value calculation unit 12 Storage section 13 Image forming section 20 Paper feeder 24 Conveyor 25 Paper feed section 30 Reading device 31 Control Unit 32 Storage section 34 Conveyor 341 Transport Path 39 Communications Department 40 Aftertreatment device. 50, 501 Reading unit 51 Reading sensor 56 Background part 561 Background surface 1 562 Background surface 2 563 Calibration Surface 564 Paper passing side 57 Switching Mechanism

Claims

1. a paper feed section that feeds paper; a conveying section that conveys paper along a conveying path; a reading unit including a reading sensor that optically reads the paper conveyed through the conveying path; an image forming unit that is located downstream of the reading unit in the conveying path and that forms an image on the conveyed paper; A control unit, the reading unit is capable of executing a plurality of reading modes including at least a first reading mode and a second reading mode different from the first reading mode, and reads the paper in any one of the reading modes selected in accordance with a print setting; The control unit causes the image forming unit to form an image on the paper at different timings depending on whether the reading mode is switched or not.

2. The image forming system according to claim 1 , wherein the reading section executes the reading mode according to a color of a paper to be read.

3. the reading unit includes a background unit disposed opposite the reading sensor across the transport path, the background unit having a plurality of background surfaces of different colors that become the background of the paper when reading; 3. The image forming system according to claim 1, wherein the switching of the reading mode is a switching of the background surface.

4. The image forming system according to claim 3 , wherein the reading section switches the background surface depending on a color of the paper to be read.

5. the paper feed unit includes a plurality of paper feed trays for storing paper; 3. The image forming system according to claim 1, wherein a different reading mode is selected in response to switching of the paper feed tray into which the paper to be read is fed.

6. 3. The image forming system of claim 1, wherein the control unit delays the timing of image formation on the paper to be read by the image forming unit in the second reading mode based on a switching time required to switch from the first reading mode to the second reading mode.

7. the paper feed unit includes a plurality of paper feed trays for storing paper; A different reading mode is selected in response to switching of the paper feed tray into which the paper to be read is fed, 7. The image forming system of claim 6, wherein when multiple sheets of paper are transported continuously and the previous and next sheets are fed from different paper feed trays, the control unit compares the delay time in the timing at which the paper is transported to the reading area of ​​the reading unit due to the change in paper feed tray with the switching time required to switch the reading mode, and if the delay time is longer than the switching time, does not delay the timing of image formation on the next sheet of paper.

8. When multiple sheets of paper are fed continuously, the distance between the previous and next sheets is set differently depending on the paper size.

7. The image forming system of claim 6, wherein the control unit compares a paper interval time corresponding to the paper interval with a switching time required to switch the reading mode, and if the paper interval time is longer than the switching time, does not delay the timing of image formation on the next paper.

9. The image forming system of claim 6, wherein when a stabilization process is performed in the image forming unit between a previous sheet and a next sheet when multiple sheets of paper are transported continuously, the control unit does not perform a process to delay the timing of image formation on the next sheet of paper in response to the switching of the reading mode, but switches the reading mode during the period when the stabilization process is being performed.

10. 3. The image forming system according to claim 1, wherein the control unit selects a reading mode to be executed based on a print setting of a print job.

11. The image forming system of claim 1 or claim 2, wherein when multiple sheets of paper are transported continuously, if the previous sheet is read in the first reading mode, and the next sheet can be read in both the first reading mode and the second reading mode, the control unit reads the next sheet in the same first reading mode as the previous sheet.

12. The image forming system of claim 1 or claim 2, wherein when multiple sheets of paper are transported continuously, if the previous sheet is not being read, the control unit starts switching the reading mode for the next sheet of paper while the previous sheet is transporting through the reading area of ​​the reading unit.

13. a correction value calculation unit that calculates a paper position correction value based on read data obtained by reading the paper with the reading unit; The image forming system of claim 1 or claim 2, further comprising a print control unit that adjusts the image forming position on at least one of the first side and the second side of the read paper based on the paper position correction value calculated by the correction value calculation unit.

14. a paper feed section that feeds paper; a conveying section that conveys paper along a conveying path; a reading unit including a reading sensor that optically reads the paper conveyed through the conveying path; an image forming unit that forms an image on the transported paper downstream of the reading unit in the transport path, the image forming system including: The reading unit is capable of executing a plurality of reading modes including at least a first reading mode and a second reading mode different from the first reading mode, and a step (a) of selecting one of the reading modes in accordance with a print setting; (b) reading the paper in the selected reading mode; (c) causing the image forming unit to form an image on the paper at different timings depending on whether the reading mode is switched or not; and (d) forming an image on the paper at the image formation timing.

15. 15. The printing method according to claim 14, wherein in said step (a), the reading mode is selected according to the color of the paper to be read.

Images