Image forming apparatus and control method for image forming apparatus

Abstract

To provide an image forming device and a method of controlling an image forming device, which allow for reducing wastepaper generated by blank feeding of a recording medium so as to prevent productivity reduction.SOLUTION: An image forming device provided herein comprises a transport unit 32 for transporting rolled paper sheets 12, an image forming unit 30 configured to form a test image 200 on the rolled paper sheet 12 transported by the transport unit 32, and an image reading unit 41 configured to read the test image 200 formed on the rolled paper sheet 12, and is configured to generate a transport variation profile of the rolled paper sheets 12 based on a result of reading of the test image 200 by the image reading unit 41 and perform image adjustment of a document image 100 to be printed according to the generated transport variation profile.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] One of the challenges facing image forming devices, such as those that print document images on roll paper, is how to deal with fluctuations in the roll paper during transport, particularly misalignment in a direction perpendicular to the paper feed direction (transport direction), known as lateral misalignment. To address this challenge, a skew detection device has been proposed that prints a lateral misalignment detection pattern on the roll paper, reads the lateral misalignment detection pattern with a skew detection sensor to detect the amount of lateral misalignment, and corrects the lateral misalignment based on the detected amount of lateral misalignment (see, for example, Patent Document 1).

[0003] However, the conventional technology described in Patent Document 1 had the problem that if the roll paper fluctuated significantly and the lateral misalignment detection pattern was printed outside the reading area of ​​the skew detection sensor, the lateral misalignment could not be corrected. For this reason, the amount of lateral misalignment must be within the reading area of ​​the skew detection sensor.

[0004] In addition, an image forming device has been proposed in which adjustment images such as registration marks for position adjustment and patches for gradation adjustment are printed on roll paper, and these adjustment images are read by an image reading unit (e.g., an in-line sensor) capable of reading the entire printed image, and corrections are made to the original image to be printed based on the reading results (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 05-043128 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-168216 Summary of the Invention [Problem to be solved by the invention]

[0006] In the case of the conventional technology described in Patent Document 2 above, the entire printed image can be read by an image reading unit (e.g., an inline sensor), so there are no restrictions on reading the adjustment image as in the case of the conventional technology described in Patent Document 1.

[0007] However, in the case of the conventional technology described in Patent Document 2, due to its configuration, the printed image is read by a downstream image reading unit (e.g., an inline sensor) and correction is made to the original image to be printed. Therefore, if the transport state of the roll paper is unstable, the amount of lateral misalignment of the printed area does not match the amount of lateral misalignment that is read, and appropriate correction cannot be made, which is a problem.

[0008] To prevent the above-mentioned problems from occurring, roll paper is fed empty until the transport state stabilizes, and printing begins once the transport state has stabilized. Because the fluctuations in the roll paper at the start of transport are particularly large and unstable, empty feeding is performed each time printing of an original image begins. As a result, the paper that is fed empty becomes waste paper, and productivity is reduced by the time it is fed empty.

[0009] Note that, here, the above-mentioned problem has been explained using the example of an image forming device that prints original images on roll paper, but this problem is not limited to image forming devices that print original images on roll paper, but also applies to image forming devices that print original images on sheet-fed machines or long paper.

[0010] The present invention has been made in consideration of the above circumstances, and aims to provide an image forming apparatus and a control method for an image forming apparatus that can reduce paper waste caused by empty feeding of recording media and prevent a decrease in productivity. [Means for solving the problem]

[0011] In order to achieve the above object, the image forming apparatus of the present invention comprises a conveying unit that conveys a recording medium, an image forming unit that forms a test image on the recording medium conveyed by the conveying unit, an image reading unit that reads the test image formed on the recording medium, and a profile creation unit that creates a conveyance fluctuation profile of the recording medium based on the reading results of the test image by the image reading unit, and the image forming unit performs image adjustment of the original image to be printed based on the conveyance fluctuation profile created by the profile creation unit. The recording medium is roll paper, and the profile creation unit creates a transport fluctuation profile when the device is turned on, when the roll paper is replaced, or when a cutting and pasting process is performed.

[0012] In addition, the control method for an image forming apparatus of the present invention is an image forming apparatus that includes a conveying unit that conveys a recording medium, an image forming unit that forms a test image on the recording medium conveyed by the conveying unit, and an image reading unit that reads the test image formed on the recording medium, and creates a conveying fluctuation profile for the recording medium based on the reading results of the test image by the image reading unit, and performs image adjustment of the original image to be printed based on the created conveying fluctuation profile. The recording medium is roll paper, and a transport fluctuation profile is created when the device is turned on, when the roll paper is replaced, or when cutting and pasting processing is performed. [Effects of the Invention]

[0013] According to the present invention, it is possible to reduce paper waste caused by empty feeding of the recording medium and prevent a decrease in productivity. Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic diagram illustrating an example of the system configuration of an image forming apparatus according to a first embodiment of the present invention. [Figure 2] 2 is a block diagram showing an example of the configuration of a control system of an image forming unit in the image forming apparatus according to the first embodiment of the present invention. FIG. [Figure 3] 10A and 10B are diagrams showing how printing of an original image starts after a certain amount of idle feeding has been performed and lateral misalignment during roll paper transport has been resolved. [Figure 4]5 is a flowchart showing an example of a procedure for creating a transport fluctuation profile in the first embodiment of the present invention. [Figure 5] 10A and 10B are diagrams showing a test image printed on roll paper and fluctuations in paper transport. [Figure 6] 6 is a flowchart showing an example of the procedure of image adjustment processing of an original image based on a conveyance fluctuation profile in the first embodiment of the present invention. [Figure 7] 3A to 3C are diagrams for explaining the operation and effect of the first embodiment of the present invention. [Figure 8] 10 is a flowchart showing an example of a procedure for creating a transport fluctuation profile in a second embodiment of the present invention. [Figure 9] 10 is a flowchart showing an example of a procedure for setting a print start position of an original image based on a transport fluctuation profile according to a second embodiment of the present invention. [Figure 10] 10A and 10B are diagrams for explaining the operation and effect of the second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, a mode for carrying out the present invention (hereinafter referred to as an "embodiment") will be described in detail with reference to the drawings. The present invention is not limited to the embodiment, and various numerical values ​​in the embodiment are merely examples. In the following description and in each drawing, the same elements or elements having the same functions will be designated by the same reference numerals, and redundant description will be omitted.

[0016] First Embodiment The printing method (image forming method) of the image forming apparatus according to the first embodiment of the present invention may be an electrophotographic method in which an image is created by irradiating a charged photosensitive drum with light and then transferred to a recording medium, or an inkjet method in which heat and pressure are applied to ink and the ink is sprayed from a nozzle onto a recording medium for printing.

[0017] In the following, an image forming apparatus according to the first embodiment will be described using an example in which the printing method is an electrophotographic method.

[0018] Fig. 1 is a schematic diagram showing an example of the system configuration of an image forming apparatus according to a first embodiment of the present invention. As shown in Fig. 1, the image forming apparatus 1 according to the first embodiment is an image forming apparatus that uses roll paper as a recording medium (recording paper), and includes a paper feed unit 10, a paper feed adjustment unit 20, an image forming unit 30, a paper processing unit 40, a paper discharge adjustment unit 50, a processing unit 60, and a paper discharge unit 70.

[0019] The paper feed unit 10 has a holder 11 to which roll paper 12, which is continuous paper wound in a roll, is detachably attached. During image formation processing, the paper feed unit 10 feeds the roll paper 12 from the holder 11 and feeds the fed roll paper 12 to the image forming unit 30 via a paper feed adjustment unit 20 using multiple transport rollers.

[0020] The paper feed adjustment unit 20 is located downstream of the paper feed unit 10 in the paper transport direction D1. To absorb the speed difference between the transport speed of the roll paper 12 in the paper feed unit 10 and the transport speed of the roll paper 12 in the subsequent image forming unit 30, the paper feed adjustment unit 20 transports the roll paper 12 in a slackened state to the image forming unit 30. The paper feed adjustment unit 20 has a sensor 21 that detects slack in the roll paper 12, and adjusts the slack in the roll paper 12 based on the detection result of the sensor 21.

[0021] The image forming section 30 is installed downstream of the paper feed adjustment section 20 in the paper conveying direction D1. The image forming section 30 includes a control section 31, a conveying section 32, an image forming unit section 33, a fixing section 34, a paper discharge conveying section 35, and an operation display section 36. Details of each component of the image forming section 30 will be described later.

[0022] The paper processing unit 40 is located downstream of the image forming unit 30 in the paper transport direction D1. The paper processing unit 40 functions as a relay device, transporting the roll paper 12 discharged from the image forming unit 30 to the paper discharge adjustment unit 50. The paper processing unit 40 has an image reading unit 41 on its transport path. The image reading unit 41 reads a test image (described below) formed on the roll paper 12 and feeds back the reading results to, for example, the control unit 31 of the image forming unit 30. The image reading unit 41 can be, for example, a line sensor in which photoelectric conversion elements are arranged in a line, or an image sensor in which photoelectric conversion elements are arranged in a matrix.

[0023] The paper discharge adjustment unit 50 is located downstream of the paper processing unit 40 in the paper transport direction D1. To absorb the difference in speed between the transport speed of the roll paper 12 in the paper processing unit 40 and the transport speed of the roll paper 12 in the subsequent processing unit 60, the paper discharge adjustment unit 50 transports the roll paper 12 in a slack state to the processing unit 60. The paper discharge adjustment unit 50 has a sensor 51 that detects slack in the roll paper 12, and adjusts the slack in the roll paper 12 based on the detection result of the sensor 51.

[0024] The processing unit 60 is located downstream of the paper discharge adjustment unit 50 in the paper transport direction D1. The processing unit 60 has a cutting unit 61, and performs processes such as cutting and pasting. Here, the cutting and pasting process is a process in which the print condition of the image formed on the transported roll paper 12 is checked, and if an image defect (printing defect) is detected, the printed image portion is cut and the roll paper 12 is spliced ​​together.

[0025] If the roll paper 12 is a label sticker, the processing unit 60 further performs a process to cut the sticker portion so that it follows the outline (outer frame) of the image formed on the label sticker being conveyed. This process allows only the label (seal member) on which the image is printed to be peeled off from the label sticker.

[0026] The paper discharge section 70 is located downstream of the processing section 60 in the paper transport direction D1. The paper discharge section 70 has a holder 71 for winding up the roll paper 12 to which the labels that will ultimately become the product have been affixed, and a holder 72 for winding up the roll paper 12 in the waste removal area other than the labels.

[0027] [Image forming unit configuration example] In the image forming section 30, which includes the components of a control section 31, a conveying section 32, an image forming unit section 33, a fixing section 34, a paper discharge conveying section 35, and an operation display section 36, the control section 31 controls the components to perform an image forming operation to form an original image and a test image used when correcting the original image on the roll paper 12. Details of the control section 31 will be described later.

[0028] The transport section 32 is composed of a transport roller and a motor that rotates the transport roller, and transports the roll paper 12 supplied from the paper feed adjustment section 20 to the image forming unit section 33 by rotating the transport roller.

[0029] The image forming unit section 33 has four image forming units for forming toner images of the respective colors, Y (yellow), M (magenta), C (cyan), and K (black), on the photosensitive drums 331Y, 331M, 331C, and 331K, which are image carriers. The image forming unit section 33 further has an intermediate transfer belt 332 and a transfer roller 333. The toner images of the respective colors transferred to the photosensitive drums 331Y, 331M, 331C, and 331K are transferred in order onto the intermediate transfer belt 332 in a superimposed state (primary transfer). As a result, a color image in which the toner images of the respective colors are superimposed is formed on the intermediate transfer belt 332.

[0030] The intermediate transfer belt 332 is endless and is stretched over multiple rollers. Driven by a drive motor (not shown), the intermediate transfer belt 332 rotates clockwise, which is the opposite direction to the rotation of the photosensitive drums 331Y, 331M, 331C, and 331K. A primary transfer unit is provided on the intermediate transfer belt 332 at a position facing the photosensitive drums 331Y, 331M, 331C, and 331K. The primary transfer unit transfers the toner images formed on the photosensitive drums 331Y, 331M, 331C, and 331K to the intermediate transfer belt 332 by applying a voltage of the opposite polarity to the toner to the intermediate transfer belt 332.

[0031] The toner image transferred onto the intermediate transfer belt 332 is then transferred onto the roll paper 12 by the transfer roller 333 (secondary transfer). In this example, when correcting an image, in addition to the toner image, a test image used when correcting the original image is transferred onto the roll paper 12.

[0032] The fixing unit 34 has a fixing roller 34a, which is a heat source, and a pressure roller 34b, and fixes the toner image on the roll paper 12 by applying heat and pressure to the toner image on the roll paper 12 transported by the transfer roller 333.

[0033] The paper discharge transport unit 35 is composed of a paper discharge roller and a motor that rotates and drives the paper discharge roller, and by rotating the paper discharge roller, transports the roll paper 12 that has been fixed in the fixing unit 34 to the paper processing unit 40.

[0034] The operation display unit 36 ​​has a touch panel that combines a display unit and an input unit, and operation keys provided around the touch panel, including a start key, a numeric keypad, etc. The operation display unit 36 ​​displays an operation screen, etc., and accepts image formation condition information regarding the type of correction, image placement, etc., input by touch operation on the operation screen or operation of the operation keys.

[0035] [Configuration of the control system for the image forming unit] Fig. 2 is a block diagram showing an example of the configuration of a control system of the image forming section 30 in the image forming apparatus 1 according to the first embodiment. As shown in Fig. 2, the image forming section 30 includes the above-mentioned control section 31, conveyance section 32, image forming unit section 33, fixing section 34, paper discharge conveyance section 35, and operation display section 36, as well as an image processing section 37, an HDD (Hard Disk Drive) 38 which is an example of a storage section, and a communication section 39.

[0036] The control unit 31 is configured to have, for example, a CPU (Central Processing Unit) 311, a ROM (Read Only Memory) 312 for storing programs executed by the CPU 311, and a RAM (Random Access Memory) 313 used as a work area for the CPU 311. Note that, as the ROM 312, an electrically erasable programmable ROM is usually used.

[0037] The control unit 31 is connected to each of the conveying unit 32, the image forming unit 33, the fixing unit 34, the paper discharge conveying unit 35, the operation display unit 36, the image processing unit 37, the HDD 38, and the communication unit 39 via a system bus 400, and controls the entire image forming unit 30. The control unit 31 further controls each unit of the paper feed unit 10 and the paper discharge unit 70 via the communication unit 39.

[0038] An external device, for example, a PC (personal computer) 300, is connected to the image forming unit 30. Image data is transmitted from the PC 300 to the image forming unit 30. The image data transmitted from the PC 300 is sent to an image processing unit 37, where image processing is performed.

[0039] Under the control of the control unit 31, the image processing unit 37 performs various types of correction processing, such as shading correction, image density correction, and color registration correction, as well as image processing, such as image compression, on the received image data as needed.

[0040] Under the control of the control unit 31, the image forming unit 33 receives image data that has been image-processed by the image processing unit 37, and forms an image on the roll paper 12 based on the image data.

[0041] In the image forming apparatus 1 configured as described above, the user can perform operations such as inputting the type (paper grade) of the roll paper 12 on the operation display unit .

[0042] The communication unit 39 is a communication interface for connecting to a network to which the components of the image forming apparatus 1 are connected. For example, the image forming unit 30 performs serial communication with the paper feed unit 10 and the paper discharge unit 70 via the communication unit 39.

[0043] [About fluctuations in roll paper during transport] One of the challenges facing the image forming apparatus 1 configured as described above, that is, the image forming apparatus 1 that uses roll paper 12 as the recording medium (recording paper), is how to deal with fluctuations in the roll paper 12 during transport. Examples of fluctuations in the roll paper 12 during transport include horizontal misalignment, which is fluctuation in a direction perpendicular to the paper feed direction (transport direction), fluctuations in vertical and horizontal magnification when forming (printing) an original image, and fluctuations in a direction oblique to the transport direction. Fluctuations in the oblique direction result in image distortion.

[0044] Conventionally, to print an original image without being affected by fluctuations in the roll paper 12 during transport, such as lateral misalignment, the roll paper 12 is fed empty by a predetermined amount, and printing of the original image begins once the transport state has stabilized, that is, once fluctuations in the roll paper 12 have settled. Here, empty feeding refers to transporting the roll paper 12 without printing an original image. Figure 3 shows how printing of the original image 100 begins after a certain amount of empty feeding has been performed and lateral misalignment during roll paper transport has settled.

[0045] In this way, if a certain amount of empty feed is performed and printing of the original image 100 is started after the lateral misalignment of the roll paper 12 during transport has settled down, the amount of roll paper 12 that has been empty fed becomes waste paper, and the productivity of the image forming device 1 will be reduced by the amount of the empty feed period.

[0046] Therefore, in the image forming apparatus 1 and its control method according to the first embodiment of the present invention, a test image is formed on the roll paper 12 being transported by the transport unit 32, the test image is read by the image reading unit 41, and a transport fluctuation profile of the roll paper 12 is created based on the reading results. Here, the test image is a test pattern for detecting transport fluctuations of the roll paper 12, and is a position adjustment image used to correct the original image 100 when printing the original image 100. The transport fluctuation profile also represents the history of transport fluctuations of the roll paper 12.

[0047] The reading results of the image reading unit 41 can be configured to be fed back to the control unit 31 in the image forming unit 30, for example. In this configuration, the control unit 31 has the function of a profile creation unit that creates a transport fluctuation profile for the roll paper 12, and creates the transport fluctuation profile for the roll paper 12 based on the reading results of the test image fed back from the image reading unit 41. This also applies to the second embodiment described below.

[0048] The transport fluctuation profile of the roll paper 12 created based on the reading results of the test image is reflected in the image adjustment of the original image 100 when the original image 100 is printed on the roll paper 12. Specifically, under the control of the control unit 31, the image forming unit 30 that prints the original image 100 on the roll paper 12 performs image adjustment (correction) of the original image 100 to be printed, for example, correction of the image formation position of the original image 100, based on the created transport fluctuation profile.

[0049] The following describes specific examples of the process of creating a conveyance fluctuation profile and the process of image adjustment in the image forming apparatus 1 and the control method thereof according to the first embodiment of the present invention. In the following, the process of creating a conveyance fluctuation profile and the process of image adjustment of the original image 100 are assumed to be executed under the control of the control unit 31.

[0050] (Creating a transport fluctuation profile) The conveyance fluctuation profile is created when the image forming apparatus 1 is turned on, when the roll paper 12 is replaced, or when a cutting and pasting process is performed in the processing unit 60. This also applies to the second embodiment described later.

[0051] 4 is a flowchart showing an example of the procedure for creating a conveyance fluctuation profile in the first embodiment of the present invention. Here, an example will be described in which the conveyance fluctuation profile creation process is performed when the device power is turned on. Also, an example will be described in which the fluctuation of the roll paper 12 during transport is a lateral deviation (fluctuation in a direction perpendicular to the paper feed direction).

[0052] When the device power is turned on, the control unit 31 drives the conveying unit 32 to start conveying the roll paper 12 (step S11), and then drives the image forming unit 33 to print a test image 200, i.e., a test pattern for detecting conveyance fluctuations of the roll paper 12, on the roll paper 12 (step S12).

[0053] Figure 5 shows a test image 200 printed on roll paper 12 and the state of paper transport fluctuations. The test image 200 shown here as an example of a position adjustment image is, for example, a register mark consisting of a cross pattern. As shown in Figure 5, paper transport fluctuations (here, lateral deviations) occur for a certain period of time after the start of transport of the roll paper 12, and this paper transport fluctuation is created as a transport fluctuation profile of the roll paper 12 using the following processing procedure.

[0054] Under the control of the control unit 31, the test image 200 printed on the roll paper 12 by the image forming unit 33 is read by the image reading unit 41 in the paper processing unit 40 at the subsequent stage.

[0055] The control unit 31 acquires the reading result of the test image 200 read by the image reading unit 41 (step S13), and then detects the coordinates of the register marks (cross pattern) of the test image from the reading result of the test image 200 (step S14).

[0056] Next, the control unit 31 detects the amount of lateral deviation of the roll paper 12 from the difference between the coordinates of the registration marks detected in step S14 and the reference coordinates (step S15), and then stores the detected amount of lateral deviation as coordinate data in RAM 313 (see Figure 2), which is an example of a memory unit (step S16).

[0057] Next, the control unit 31 determines whether the operation to detect the amount of lateral misalignment has been performed n times (n is an integer greater than or equal to 2) (step S17). If it has not been performed n times (NO in S17), the control unit 31 returns to step S11 and executes the above-mentioned series of processes until it has been performed n times. By repeating this series of processes, the series of processes from starting transport of the roll paper 12 → printing a test image → detecting the amount of lateral misalignment is executed multiple times (n times). The more times this is executed, the more accurate the transport fluctuation profile that will be created later can be.

[0058] When the above-described series of processes has been performed n times (YES in S17), the control unit 31 creates a transport fluctuation profile of the roll paper 12 from the standard deviation of the coordinate data repeatedly acquired and stored in RAM 313, and stores and retains the profile in HDD 38 (see Figure 2), which is an example of a storage unit (step S18).

[0059] As described above, in the image forming apparatus 1 and control method thereof according to the first embodiment, when the transport unit 32 starts transporting the roll paper 12, the image reading unit 41 reads the test image formed on the roll paper 12, and a process is performed to create a transport fluctuation profile for the roll paper 12 based on the read results. In this example, the transport fluctuation profile is a lateral deviation profile that plots fluctuations in the amount of lateral deviation that occurs over time in the transport direction of the roll paper 12, and is created based on the history of multiple (n) lateral deviations. This also applies to the second embodiment described below.

[0060] (Image adjustment processing of original image) Next, a process of performing image adjustment of the original image 100 based on the conveyance fluctuation profile created as described above will be described. Fig. 6 is a flowchart showing an example of the procedure of image adjustment processing of the original image 100 based on the conveyance fluctuation profile in the first embodiment of the present invention.

[0061] The control unit 31 first acquires a transport fluctuation profile from the HDD 38 (see FIG. 2), which is an example of a storage unit (step S21), and then performs image adjustment of the original image 100 based on this acquired transport fluctuation profile (step S22). In the process of creating the transport fluctuation profile described above, a transport fluctuation profile is created for when the fluctuation of the roll paper 12 during transport is a lateral deviation. Therefore, in the image adjustment of the original image 100 in step S22, a process of adjusting (correcting) the image formation position of the original image 100 in a direction perpendicular to the paper feed direction is performed so as to cancel the lateral deviation.

[0062] When the image adjustment of the original image 100 is completed, the control unit 31 drives the conveying unit 32 to start conveying the roll paper 12 (step S23), and then drives the image forming unit 33 to start printing (image formation) the original image 100 after the image adjustment (i.e., after adjusting the image formation position) onto the roll paper 12 (step S24).

[0063] As described above, the image adjustment process for the original image 100 in the image forming apparatus 1 and its control method according to the first embodiment adjusts the image of the original image 100 based on the transport fluctuation profile of the paper transport fluctuation, so that the original image 100 can be printed from the start of transport of the roll paper 12. This eliminates the need to feed the roll paper 12 empty until the transport state stabilizes, as shown in Fig. 7, and therefore reduces paper waste caused by empty feeding and prevents a decline in productivity.

[0064] Second Embodiment The printing method (image forming method) of the image forming apparatus according to the second embodiment of the present invention may be an electrophotographic method or an inkjet method, as with the image forming apparatus according to the first embodiment. Note that the system configuration of the image forming apparatus according to the second embodiment is the same as that of the image forming apparatus according to the first embodiment, and therefore detailed description thereof will be omitted.

[0065] In the second embodiment of the present invention, as in the first embodiment, with the aim of reducing paper waste caused by empty feeding and suppressing declines in productivity, a transport fluctuation profile for roll paper 12 is created at the start of transport based on the results of reading a test image formed on roll paper 12. When original image 100 is printed on roll paper 12, this transport fluctuation profile is reflected in the print start position of original image 100. Specifically, under the control of control unit 31, image forming unit 30, which prints original image 100 on roll paper 12, sets the print start position of original image 100 based on the transport fluctuation profile.

[0066] The following describes specific examples of the process of creating a transport fluctuation profile and the process of setting a print start position for the original image 100 in the image forming apparatus 1 and its control method according to the second embodiment of the present invention. In the following, it is assumed that the process of creating a transport fluctuation profile and the process of setting a print start position for the original image 100 are executed under the control of the control unit 31.

[0067] (Creating a transport fluctuation profile) 8 is a flowchart showing an example of the procedure for creating a conveyance fluctuation profile in the second embodiment of the present invention. Here, we will explain an example in which the conveyance fluctuation profile creation process is performed when the device power is turned on. We will also explain an example in which the fluctuation of the roll paper 12 during conveyance is a lateral deviation. These points are the same as in the first embodiment.

[0068] When the device power is turned on, the control unit 31 drives the conveying unit 32 to start conveying the roll paper 12 (step S31), and then drives the image forming unit 33 to print a test image 200, i.e., a test pattern for detecting conveyance fluctuations of the roll paper 12, on the roll paper 12 (step S32).

[0069] Under the control of the control unit 31, the test image 200 printed on the roll paper 12 by the image forming unit 33 is read by the image reading unit 41 in the paper processing unit 40 at the subsequent stage.

[0070] The control unit 31 acquires the reading result of the test image 200 read by the image reading unit 41 (step S33), and then detects the coordinates of the register marks (cross pattern) of the test image from the reading result of the test image 200 (step S34).

[0071] Next, the control unit 31 detects the amount of lateral deviation of the roll paper 12 from the difference between the coordinates of the registration marks detected in step S34 and the reference coordinates (step S35), and then stores the detected amount of lateral deviation as coordinate data in RAM 313 (see Figure 2), which is an example of a memory unit (step S36).

[0072] Next, the control unit 31 determines whether the operation to detect the amount of lateral misalignment has been performed n times (n is an integer greater than or equal to 2) (step S37), and if it has not been performed n times (NO in S37), the control unit 31 returns to step S31 and executes the above-mentioned series of processes until it has been performed n times. By repeating this series of processes, the series of processes starting the transport of the roll paper 12 → printing a test image → detecting fluctuations in the amount of lateral misalignment is executed multiple times (n times).

[0073] When the above-described series of processes has been performed n times (YES in S37), the control unit 31 creates a transport fluctuation profile of the roll paper 12 from the standard deviation of the coordinate data repeatedly acquired and stored in RAM 313, and stores and retains the profile in HDD 38 (see Figure 2), which is an example of a storage unit (step S38).

[0074] As described above, in the image forming apparatus 1 and its control method according to the second embodiment, when the transport unit 32 starts transporting the roll paper 12, the image reading unit 41 reads the test image formed on the roll paper 12, and a process is performed to create a transport fluctuation profile for the roll paper 12 based on the read results. In this example, the transport fluctuation profile is a lateral deviation profile, and is created based on the history of multiple (n) lateral deviations.

[0075] (Print start position setting process for document image) Next, a process for setting the print start position of the original image 100 based on the transport fluctuation profile created as described above will be described. Fig. 9 is a flowchart showing an example of the procedure for setting the print start position of the original image 100 based on the transport fluctuation profile in the second embodiment of the present invention.

[0076] The control unit 31 first acquires a transport fluctuation profile from the HDD 38 (see FIG. 2), which is an example of a storage unit (step S41), and then, based on this acquired transport fluctuation profile, estimates the position (i.e., the position in the paper transport direction) where the transport fluctuation of the roll paper 12 stabilizes (contains) (step S42). If the transport fluctuation of the roll paper 12 is lateral deviation, the position where the transport fluctuation stabilizes can be estimated as the point at which the amount of lateral deviation remains below a predetermined value for a predetermined period of time. The predetermined value and the predetermined period can be set arbitrarily.

[0077] Once the position where the transport fluctuation stabilizes has been estimated, the control unit 31 drives the transport unit 32 to start transporting the roll paper 12 (step S43), and then determines whether the transport position of the roll paper 12 is the position where the transport fluctuation estimated in step S42 stabilizes (step S44). If it determines that the roll paper 12 has not been transported to the position where the transport fluctuation stabilizes (NO in S44), the control unit 31 returns to step S43 and continues transporting the roll paper 12. As a result, the roll paper 12 is fed empty to the position where the transport fluctuation stabilizes.

[0078] If it is determined that the roll paper 12 has been transported to a position where the transport fluctuation has stabilized (YES in S44), the control unit 31 starts printing the original image (step S45). As a result, after the roll paper 12 has been fed empty to a position where the transport fluctuation has stabilized, printing of the original image starts from the position where the transport fluctuation has stabilized.

[0079] As described above, according to the process for setting the print start position of the original image 100 in the image forming apparatus 1 and its control method of the second embodiment, the position where the transport fluctuation of the roll paper 12 stabilizes (contains) can be estimated based on the transport fluctuation profile of the paper transport fluctuation, and the original image 100 can be printed from that position.

[0080] As a result, as shown in Figure 10, although blank feeding is required up to the printing start position, by estimating the position where the transport fluctuation of the roll paper 12 stabilizes, the amount of blank feeding can be minimized, thereby reducing paper waste caused by blank feeding. Furthermore, in the example shown in Figure 10, the productivity of the image forming apparatus 1 can be increased by three original images compared to the example shown in Figure 3, in which a predetermined fixed amount of blank feeding is performed. Furthermore, by avoiding the fluctuation region at the start of transport of the roll paper 12 and allowing the original image to be printed with the transport of the roll paper 12 more stable, higher quality printed images can be formed.

[0081] <Application examples and modifications> It should be noted that the present invention is not limited to the above-described embodiments, and various other applications and modifications are possible without departing from the spirit of the present invention as set forth in the claims. For example, the above-described embodiments have described in detail and specifically the configurations of the image forming apparatus and the control method thereof in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all of the described configurations.

[0082] Furthermore, in each of the above-described embodiments, the control unit 31 in the image forming unit 30 has the function of a profile creation unit and is configured to create a transport fluctuation profile for the roll paper 12, but this configuration is not limited to this. That is, the profile creation unit can be provided independently as a single functional unit, or the function of the profile creation unit can be given to a control unit in another functional unit in the image forming unit 30.

[0083] Furthermore, in each of the above-described embodiments, the present invention has been described using an image forming apparatus that prints an original image on roll paper as an example, but the present invention is not limited to application to image forming apparatuses that print original images on roll paper, and can also be applied to image forming apparatuses that print original images on sheet-fed machines or long sheets of paper. [Explanation of symbols]

[0084] 10...paper feed section, 12...roll paper, 20...paper feed adjustment section, 30...image forming section, 31...control section, 32...conveyance section, 33...image forming unit section, 34...fixing section, 35...paper discharge conveyance section, 36...operation display section, 37...image processing section, 38...HDD (Hard Disk Drive), 39...communication section, 40...paper processing section, 41...image reading section, 50...paper discharge adjustment section, 60...processing processing section, 70...paper discharge section, 100...original image, 200...test image (test pattern)

Claims

1. a conveying unit that conveys the recording medium; an image forming unit that forms a test image on the recording medium conveyed by the conveying unit; an image reading unit that reads the test image formed on the recording medium; a profile creation unit that creates a conveyance fluctuation profile of the recording medium based on the result of reading the test image by the image reading unit; Equipped with the image forming unit performs image adjustment of the document image to be printed based on the transport fluctuation profile created by the profile creation unit, the recording medium is roll paper, The profile creation unit creates the transport fluctuation profile when the device is powered on, when the roll paper is replaced, or when a cutting and pasting process is performed. Image forming device.

2. The image forming unit starts printing the original image, the image of which has been adjusted based on the transport fluctuation profile, from the time when transport of the original image begins. The image forming apparatus according to claim 1 .

3. The profile creation unit creates the transport fluctuation profile based on the result of reading the test image by the image reading unit at the start of transport of the recording medium.

3. The image forming apparatus according to claim 1.

4. The profile creation unit creates a conveyance fluctuation profile based on fluctuations during conveyance of the recording medium. The image forming apparatus according to claim 3 .

5. The fluctuation during transport of the recording medium is a fluctuation in a direction perpendicular to the transport direction during transport of the recording medium. The image forming apparatus according to claim 4 .

6. The fluctuation during conveyance of the recording medium is a vertical / horizontal magnification fluctuation during formation of the original image. The image forming apparatus according to claim 4 .

7. The fluctuation during transport of the recording medium is a fluctuation in a direction oblique to the transport direction during transport of the recording medium. The image forming apparatus according to claim 4 .

8. a conveying unit that conveys the recording medium; an image forming unit that forms a test image on the recording medium conveyed by the conveying unit; an image reading unit that reads the test image formed on the recording medium; A control method for an image forming apparatus comprising: creating a transport fluctuation profile of the recording medium based on the result of reading the test image by the image reading unit; performing image adjustment of the document image to be printed based on the created transport fluctuation profile; the recording medium is roll paper, The transport fluctuation profile is created when the device power is turned on, when the roll paper is replaced, or when cutting and pasting is performed. A control method for an image forming apparatus.

Images