Recording-medium carrying device, image forming apparatus, post-processor, and method and program for controlling transportation

Abstract

To correctly detect a position of a recording medium carried on a transport pathway.SOLUTION: An MFP comprises a timing roller that carries a recording medium in a transport direction along a transport pathway, a CIS 201 that has a plurality of detecting elements having a detection area directed in a first direction, the plurality of detecting elements being arrayed in a second direction intersecting with the transport and first directions, and a detecting unit 200 that allows the CIS 201 and the recording medium to relatively move in the second direction.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a recording medium transport device, an image forming device, a post-processing device, a transport control method, and a transport control program, and relates to a recording medium transport device that transports a recording medium along a transport path, an image forming device or post-processing device that is equipped with the recording medium transport device, a transport control method executed by the recording medium transport device, and a transport control program that causes a computer to execute the recording medium transport control method. [Background technology]

[0002] An image forming apparatus, typified by an MFP (Multi Function Peripheral), forms an image on a recording medium that is transported thereto. A post-processing device performs post-processing, such as punching holes, on the recording medium transported from the MFP. The transport path along which the recording medium is transported can transport recording media of multiple sizes with different lengths in a direction perpendicular to the transport direction of the recording medium. As a result, the position of the recording medium transported along the transport path may not be fixed in the direction perpendicular to the transport direction. For this reason, a technology is known that provides a sensor to detect deviation of the recording medium while it is being transported along the transport path, and detects the position of the recording medium along the transport path.

[0003] However, paper dust may adhere to the sensor that detects the misalignment, which may result in the sensor mistaking the paper dust for the recording medium. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-096385 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a recording medium transport device that can accurately detect the position of a recording medium transported along a transport path.

[0006] Another object of the present invention is to provide an image forming apparatus capable of forming an image at an appropriate position on a recording medium.

[0007] A further object of the present invention is to provide a post-processing device that can process a recording medium at an appropriate position.

[0008] It is still another object of the present invention to provide a transport control method that can accurately detect the position of a recording medium transported along a transport path.

[0009] It is still another object of the present invention to provide a transport control program that can accurately detect the position of a recording medium transported along a transport path. [Means for solving the problem]

[0010] According to one aspect of the present invention, a recording medium transport device includes a transport unit that transports a recording medium in a transport direction along a transport path, a sensor having a plurality of detection elements having detection areas facing a first direction, the plurality of detection elements being arranged in a second direction that intersects the transport direction and the first direction, and a movement control unit that moves the sensor and the recording medium relative to each other in the second direction.

[0011] According to another aspect of the present invention, an image forming apparatus includes the above-mentioned recording medium conveying device and an image forming unit that forms an image on the recording medium conveyed by the conveying unit, and the image forming unit determines the position of the image to be formed on the recording medium based on the medium position.

[0012] According to yet another aspect of the present invention, a post-processing device includes the above-mentioned recording medium conveying device and a post-processing unit that processes the recording medium conveyed by the conveying unit, and the post-processing unit determines a position for processing the recording medium based on the medium position.

[0013] According to yet another aspect of the present invention, a transport control method is a transport control method executed by a recording medium transport device, the recording medium transport device comprising: a transport unit that transports a recording medium in a transport direction along a transport path; a sensor in which a plurality of detection elements having detection areas extending in a first direction are arranged in a second direction that intersects the transport direction and the first direction; and a movement control unit that moves the sensor and the recording medium relatively in the second direction, and includes a specific element detection step that detects a specific element from among the plurality of detection elements that has an output different from other detection elements; and a relative position determination step that determines the relative position of the sensor and the recording medium in response to the detection of the specific element.

[0014] According to yet another aspect of the present invention, a transport control program is a transport control program executed by a computer that controls a recording medium transport device, the recording medium transport device comprising: a transport unit that transports a recording medium in a transport direction along a transport path; a sensor in which a plurality of detection elements having detection areas extending in a first direction are arranged in a second direction that intersects the transport direction and the first direction; and a movement control unit that moves the sensor and the recording medium relatively in the second direction, and causes the computer to execute a specific element detection step that detects a specific element from among the plurality of detection elements that has an output different from other detection elements; and a relative position determination step that determines the relative position of the sensor and the recording medium in response to the detection of the specific element. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a first perspective view showing the appearance of an MFP according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view schematically illustrating an example of the internal configuration of an MFP. [Figure 3] FIG. 2 is a diagram illustrating an example of a detailed configuration of a detection mechanism. [Figure 4] FIG. 10 is a diagram illustrating movement of a CIS. [Figure 5] FIG. 2 is a block diagram showing an outline of the hardware configuration of an MFP. [Figure 6]FIG. 2 is a diagram illustrating an example of functions of a CPU included in the MFP. [Figure 7] 10 is a flowchart illustrating an example of the flow of a transport control process. [Figure 8] FIG. 4 is a diagram illustrating an example of a timing roller moving mechanism. [Figure 9] FIG. 10 is a diagram illustrating movement of a timing roller. [Figure 10] FIG. 2 is an enlarged view showing the internal configuration of the post-processing device. [Figure 11] FIG. 2 is a first cross-sectional view showing an enlarged view of a punch unit and its vicinity. [Figure 12] FIG. 2 is a second cross-sectional view showing an enlarged view of the restricting member and its vicinity. [Figure 13] FIG. 10 is a third cross-sectional view showing an enlarged view of the restricting member and its vicinity. [Figure 14] FIG. 4 is a fourth cross-sectional view showing an enlarged view of the restricting member and its vicinity. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same components are designated by the same reference numerals. The names and functions of these components are also the same. Therefore, detailed description thereof will not be repeated.

[0017] FIG. 1 is a first perspective view showing the appearance of an MFP according to one embodiment of the present invention. Referring to FIG. 1, MFP (Multi Function Peripheral) 1 is an example of an image forming apparatus. Here, an X direction, a Y direction, and a Z direction are defined, which intersect perpendicularly with each other. The X direction and the Y direction are parallel to the horizontal plane. Within the Y direction, the direction from the rear to the front of MFP 1 (the direction from the positive side to the negative side in the Y direction) is referred to as the front direction, and the horizontal direction from the front to the rear (the direction from the negative side to the positive side in the Y direction) is referred to as the rear direction.

[0018] 2 is a cross-sectional view showing an example of the internal configuration of an MFP. Referring to FIGS. 1 and 2, MFP 1 includes a document reading unit 2 that reads a document, an image forming unit 3 that forms an image on a sheet based on image data, a paper feed unit 4 that supplies paper to image forming unit 3, and a post-processing device 100 that performs post-processing on the paper on which the image has been formed.

[0019] The document reading unit 2 exposes the image of a document set on a document glass 11 with an exposure lamp 13 attached to a slider 12 that moves below the document glass. Light reflected from the document is guided to a lens 16 by a mirror 14 and two reflecting mirrors 15 and 15A, and forms an image on a CCD (Charge Coupled Devices) sensor 18.

[0020] The reflected light that forms an image on the CCD sensor 18 is converted into image data as an electrical signal within the CCD sensor 18. The image data is converted into printing data in cyan (C), magenta (M), yellow (Y), and black (K) and output to the image forming unit 3.

[0021] The image forming unit 3 includes image forming units 20Y, 20M, 20C, and 20K for yellow, magenta, cyan, and black, respectively. Here, "Y," "M," "C," and "K" represent yellow, magenta, cyan, and black, respectively. An image is formed by driving at least one of the image forming units 20Y, 20M, 20C, and 20K. A full-color image is formed when all of the image forming units 20Y, 20M, 20C, and 20K are driven. Print data for yellow, magenta, cyan, and black is input to the image forming units 20Y, 20M, 20C, and 20K, respectively. The image forming units 20Y, 20M, 20C, and 20K differ only in the color of the toner they use. Therefore, the image forming unit 20Y for forming a yellow image will be described here.

[0022] The image forming unit 20Y includes an exposure device 21Y, a photosensitive drum 23Y, a charging roller 22Y, a developing unit 24Y, and a primary transfer roller 25Y. Around the photosensitive drum 23Y, the charging roller 22Y, the exposure device 21Y, the developing unit 24Y, the primary transfer roller 25Y, and the drum cleaning blade 27Y are arranged in this order along the rotational direction of the photosensitive drum 23Y. Yellow printing data is input to the exposure device 21Y. The photosensitive drum 23Y is an image carrier. The charging roller 22Y uniformly charges the surface of the photosensitive drum 23Y. The primary transfer roller 25Y transfers the toner image formed on the photosensitive drum 23Y onto an intermediate transfer belt 30, which is also an image carrier, by the action of an electric field.

[0023] After being charged by the charging roller 22Y, the photoreceptor drum 23Y is irradiated with laser light emitted by the exposure device 21Y. The exposure device 21Y exposes the image-corresponding portion of the surface of the photoreceptor drum 23Y. This forms an electrostatic latent image on the photoreceptor drum 23Y. Next, the developing device 24Y develops the electrostatic latent image formed on the photoreceptor drum 23Y with charged toner. Specifically, toner is placed on the electrostatic latent image formed on the photoreceptor drum 23Y by the action of electric field force, thereby forming a toner image on the photoreceptor drum 23Y. The toner image formed on the photoreceptor drum 23Y is transferred onto the intermediate transfer belt 30, which is an image carrier, by the action of electric field force using the primary transfer roller 25Y. Any toner remaining on the photoreceptor drum 23Y that has not been transferred is removed from the photoreceptor drum 23Y by the drum cleaning blade 27Y.

[0024] The intermediate transfer belt 30 is suspended tightly by a drive roller 33 and a driven roller 34. When the drive roller 33 rotates counterclockwise in FIG. 2, the intermediate transfer belt 30 rotates counterclockwise in the drawing at a predetermined speed. As the intermediate transfer belt 30 rotates, the driven roller 34 rotates counterclockwise.

[0025] As a result, the image forming units 20Y, 20M, 20C, and 20K sequentially transfer toner images onto the intermediate transfer belt 30. The timing at which each of the image forming units 20Y, 20M, 20C, and 20K transfers a toner image onto the intermediate transfer belt 30 is adjusted based on the detection of the reference marks on the intermediate transfer belt 30. As a result, yellow, magenta, cyan, and black toner images are superimposed on the intermediate transfer belt 30.

[0026] The toner image formed on the intermediate transfer belt 30 is transferred to paper by the action of electric field force by the secondary transfer roller 26, which is a transfer member. The paper is transported by timing roller 31 to a nip portion where the intermediate transfer belt 30 and secondary transfer roller 26 come into contact. The paper with the transferred toner image is transported to fixing roller 32, where it is heated and pressed. This melts the toner and fixes it to the paper. The paper is then transported to post-processing device 100.

[0027] When forming a full-color image, the MFP 1 drives all of the image forming units 20Y, 20M, 20C, and 20K. When forming a monochrome image, the MFP 1 drives only one of the image forming units 20Y, 20M, 20C, and 20K. It is also possible to form an image by combining two or more of the image forming units 20Y, 20M, 20C, and 20K. Here, we will explain an example in which the MFP 1 employs a tandem system equipped with image forming units 20Y, 20M, 20C, and 20K that form four color toners on paper. However, the MFP 1 may also form images using a four-cycle system in which four color toners are transferred sequentially onto paper using a single photosensitive drum.

[0028] Paper feed cassettes 35 and 35A are loaded with paper sheets of different sizes. The paper sheets stored in paper feed cassettes 35 and 35A are supplied to transport path 39 by take-out rollers 36 and 36A attached to paper feed cassettes 35 and 35A, respectively, and sent to timing rollers 31 by paper feed rollers 37. A detection unit 200 is disposed upstream of timing rollers 31 in the transport direction. Detection unit 200 detects the position of the paper sheets in the width direction, which is perpendicular to the transport direction of the paper sheets.

[0029] Image forming units 20Y, 20M, 20C, and 20K adjust the position of the toner image formed on intermediate transfer belt 30 based on the widthwise position of the paper detected by detection unit 200. As a result, the toner image is formed at a position corresponding to the widthwise position of the paper, so that even if the paper being transported along transport path 39 shifts widthwise within transport path 39, the toner image is transferred to the appropriate position on the paper at the nip portion.

[0030] The post-processing device 100 receives the paper on which an image has been formed from the image forming unit 3. The post-processing device 100 includes a punch unit 101, which performs a punching process to form punch holes in the paper, and outputs the punched paper to a paper output tray 138.

[0031] FIG. 3 is a diagram illustrating an example of the detailed configuration of the detection unit. FIG. 3 is a diagram illustrating the detection unit 200 as viewed from the negative side toward the positive side in the X direction. Referring to FIG. 3, the detection unit 200 includes a CIS (Contact Image Sensor) 201, a motor 203, a position sensor 205, and a cleaning unit 207. The transport direction in which the paper P is transported is from the negative side toward the positive side in the Z direction. The CIS 201 includes a plurality of photoelectric conversion elements 202 each having a detection area facing the positive side in the X direction. The plurality of photoelectric conversion elements 202 are arranged in a direction parallel to the Y direction. The CIS 201 includes an elongated light source extending in the Y direction. The CIS 201 is a reflective sensor that irradiates light from the light source toward the positive side in the X direction and receives light reflected by an object with the photoelectric conversion element 202. The length of the detection area in the X direction is predetermined. Note that a transmissive sensor may be used instead of the CIS 201. The output of each of the photoelectric conversion elements 202 included in the CIS 201 differs depending on whether or not a sheet of paper P is present in the detection area.

[0032] The CIS 201 is connected to the housing of the MFP 1 in a state where it can move in a direction parallel to the Y direction. For example, the CIS 201 is connected to a guide rail parallel to the Y direction provided on the housing of the MFP 1 in a state where it can slide. The CIS 201 is connected to the motor 203 by a rack-and-pinion mechanism. Therefore, when the motor 203 operates, the CIS 201 moves in a direction parallel to the Y direction. The motor 203 is a stepping motor. Therefore, the amount of movement of the CIS 201 is controlled by controlling the rotation angle of the motor 203. Furthermore, the position of the CIS 201 in the Y direction is determined from the rotation angle of the motor 203.

[0033] The position sensor 205 is a photoelectric sensor that detects the CIS 201 when it is positioned at its home position. The home position of the CIS 201 is a predetermined position. The position of the CIS 201 in the Y direction relative to the home position is determined from the angle by which the motor 203 has rotated from the point in time when the position sensor 205 detects the CIS 201.

[0034] The position of the CIS 201 in the Y direction is determined so that some of the multiple photoelectric conversion elements 202 overlap with the paper P in the X direction, and other parts do not overlap with the paper P in the X direction. The length of the paper P in the Y direction varies depending on the type of paper. The type of paper P transported along the transport path 39 is predetermined, and therefore the range through which the edge of the paper P in the Y direction passes is also predetermined. It is desirable that the paper is always transported at the same position along the transport path 39 in the Y direction. However, depending on the type of paper P and the behavior of the paper P when taken out by the take-out rollers 36, the paper is not necessarily transported at the same position, but it is known that it will be within a predetermined range. Hereinafter, the range through which the edge of the paper P in the Y direction passes will be referred to as the allowable range.

[0035] Distance L1 indicates the distance that CIS 201 has moved from the home position. Distance L1 is the position of CIS 201 when the multiple photoelectric conversion elements 202 overlap with the allowable range in the Y direction. As a result, the boundary between a first group of multiple photoelectric conversion elements 202 that detects paper P and a second group that does not detect paper P is detected as the edge of paper P in the Y direction. Distance L2 indicates the distance from the edge of CIS 201 to the photoelectric conversion element 202 located at the boundary.

[0036] The CIS 201 is disposed at a position where the distance to the paper P being transported on the transport path 39 is equal to or less than a predetermined distance. The CIS 201 may come into contact with the paper P. As a result, paper dust may adhere to the CIS 201. The output value of the photoelectric conversion element 202 located at the portion where paper dust is attached is closer to the output value when paper P is present than the output value when paper P is not present in the detection area, because paper dust is present in the detection area. As a result, the position of the portion where paper dust is attached may be erroneously detected as the edge of paper P in the Y direction.

[0037] The cleaning unit 207 cleans the surface of the CIS 201 on which the multiple photoelectric conversion elements 202 are arranged. The cleaning unit 207 includes a brush and a brush movement mechanism. The brush is configured, for example, by wrapping a cloth made of looped polyester fibers around a metal shaft. The brush movement mechanism holds the brush and moves it parallel to the Y direction with the tip of the brush in contact with the surface on which the multiple photoelectric conversion elements 202 of the CIS 201 are arranged. This allows the brush to remove paper dust and other particles adhering to the detection areas of the multiple photoelectric conversion elements 202 of the CIS 201.

[0038] FIG. 4 is a diagram illustrating the movement of the CIS. Note that the motor 203 and the cleaning unit 207 are omitted from FIG. 4. The upper part of FIG. 4 shows a state in which paper dust D is attached to a position of the CIS 201 near a portion corresponding to the edge of the paper P in the Y direction. The portion of the CIS 201 where the paper dust D is attached is close to the position of the edge of the paper P in the Y direction. The output value of the photoelectric conversion element 202 in the portion where the paper dust D is attached is closer to the output value of the photoelectric conversion element 202 in the portion that overlaps with the paper P in the X direction than the output value of the photoelectric conversion element 202 in the portion that does not overlap with the paper P in the X direction. Therefore, from the output values ​​of the multiple photoelectric conversion elements 202 in the CIS 201, the position of the portion of the CIS 201 where the paper dust D is attached is erroneously detected as the edge of the paper P in the Y direction.

[0039] In the present embodiment, the MFP 1 moves the CIS 201 to a position where the photoelectric conversion elements 202 in the portion of the CIS 201 to which paper dust D is attached do not overlap in the X direction with the Y-direction edge of the paper P. Specifically, as shown in the lower part of FIG. 4 , the CIS 201 is moved by a distance L3 to a position where the photoelectric conversion elements 202 in the portion of the CIS 201 that overlaps with the paper dust D overlap with the paper P in the X direction. As a result, the output value of the photoelectric conversion elements 202 in the portion of the CIS 201 that overlaps with the paper dust D becomes the same as the output value of the photoelectric conversion elements 202 among the other multiple photoelectric conversion elements 202 that are positioned to overlap with the paper P in the X direction. Therefore, the boundary between a first group of the multiple photoelectric conversion elements 202 that detects the paper P and a second group that does not detect the paper P is detected as the edge of the paper P in the Y direction.

[0040] 5 is a block diagram showing an outline of the hardware configuration of an MFP 1. Referring to FIG. 5, MFP 1 includes a main circuit 50, a document reading unit 2, an image forming unit 3, a paper feed unit 4, an operation panel 5 as a user interface, and a detection unit 200.

[0041] Main circuit 50 includes a CPU (Central Processing Unit) 51 that controls the entire MFP 1, a communication interface (I / F) unit 52, a ROM (Read Only Memory) 53, a RAM (Random Access Memory) 54, a hard disk drive (HDD) 55 as a large-capacity storage device, a facsimile unit 56, and an external storage device 58. CPU 51 is connected to document reading unit 2, image forming unit 3, paper feed unit 4, operation panel 5, and detection unit 200, and controls the entire MFP 1.

[0042] The ROM 53 stores the program executed by the CPU 51 or data required to execute the program. The RAM 54 is used as a work area when the CPU 51 executes the program. The RAM 54 also temporarily stores image data continuously sent from the document reading unit 2.

[0043] The operation panel 5 is provided on the top of the MFP 1. The operation panel 5 includes a display unit and an operation unit. The display unit is, for example, a liquid crystal display (LCD) that displays an instruction menu for the user, information about acquired image data, etc. Note that instead of the LCD, any device that displays images, such as an organic electroluminescence (EL) display, can be used. The operation unit includes a touch panel and a hard key unit. The touch panel is provided with its detection surface superimposed on the upper or lower surface of the display unit. The hard key unit includes a plurality of hard keys.

[0044] The communication I / F unit 52 is an interface for connecting the MFP 1 to a network. The communication I / F unit 52 communicates with other computers connected to the network using a communication protocol such as TCP (Transmission Control Protocol) or FTP (File Transfer Protocol). The network to which the communication I / F unit 52 is connected is a local area network (LAN), and the connection type may be wired or wireless. The network is not limited to a LAN, and may be a wide area network (WAN), a public switched telephone network (PSTN), the Internet, or the like.

[0045] Facsimile unit 56 is connected to the public switched telephone network (PSTN) and transmits facsimile data to the PSTN or receives facsimile data from the PSTN. Facsimile unit 56 stores the received facsimile data in HDD 55, converts it into print data that can be printed by image forming unit 3, and outputs it to image forming unit 3. As a result, image forming unit 3 forms an image of the facsimile data received by facsimile unit 56 on paper. Facsimile unit 56 also converts the data stored in HDD 55 into facsimile data and transmits it to a facsimile device connected to the PSTN.

[0046] The external storage device 58 is controlled by the CPU 51, and is equipped with a CD-ROM (Compact Disk Read Only Memory) 59 or a semiconductor memory. In this embodiment, an example will be described in which the CPU 51 executes a program stored in the ROM 53. The CPU 51 may control the external storage device 58 to read a program to be executed by the CPU 51 from the CD-ROM 59, store the read program in the RAM 54, and execute the program.

[0047] The recording medium for storing the program executed by the CPU 51 is not limited to the CD-ROM 59, but may be a flexible disk, a cassette tape, an optical disk, a semiconductor memory, or the like. Optical disks include magnetic optical discs (MOs), mini discs (MDs), and digital versatile discs (DVDs). Semiconductor memories include IC cards, optical cards, mask ROMs, and erasable programmable ROMs (EPROMs). Furthermore, the CPU 51 may load a program stored in the HDD 55 into the RAM 54 and execute it. Programs stored in the HDD 55 include programs downloaded by the CPU 51 from a computer connected to the network and programs written to the HDD 55 by a computer connected to the network. The program referred to here includes not only programs directly executable by the CPU 51, but also source programs, compressed programs, encrypted programs, and the like.

[0048] Fig. 6 is a diagram showing an example of functions of a CPU included in the MFP. The functions shown in Fig. 6 are realized by CPU 51 as CPU 51 executes a transport control program stored in ROM 53, HDD 55, or CD-ROM 59. Referring to Fig. 6, CPU 51 included in MFP 1 includes a transport control unit 61, a transport position notification unit 63, a sensor control unit 65, a movement control unit 67, a transport position detection unit 69, and a cleaning control unit 71.

[0049] The transport control unit 61 controls the paper feed unit 4 to transport the paper P along the transport path. In response to the CPU 51 accepting a print job, the transport control unit 61 determines the type of paper P to be transported. The print job is input to the MFP 1. When a user operates the operation panel 5 to specify image data and set printing conditions, the CPU 51 generates a print job. The image data includes image data output by the document reading unit 2 after reading a document and image data stored in the HDD 55. Furthermore, when a user operates a personal computer (PC) to specify image data and set printing conditions, the PC generates a print job. The PC transmits the print job to the MFP 1. When the communication I / F unit 52 receives a print job from the PC, the CPU 51 accepts the print job. The printing conditions include the type of paper P to be used for image formation. The paper type includes the paper size.

[0050] The transport control unit 61 transports the paper P stored in one of the paper feed cassettes 35, 35A, and 35C that stores the type of paper P specified by the printing conditions. In this case, the size of the paper P in a direction perpendicular to the transport direction is determined from the direction of the paper P stored in the cassette. The direction perpendicular to the transport direction of the transported paper P is called the width direction. In this embodiment, the width direction is the direction parallel to the Y direction. The transport control unit 61 outputs the width size of the paper P to the sensor control unit 65.

[0051] The transport control unit 61 controls the drive motor that operates the timing roller 31, and adjusts the timing at which the timing roller 31 starts transporting the paper P. The transport control unit 61 outputs the timing at which the transport of the paper P starts to the sensor control unit 65.

[0052] The sensor control unit 65 controls the CIS 201. The sensor control unit 65 operates the CIS 201 and acquires the output values ​​of each of the multiple photoelectric conversion elements 202 that the CIS 201 has. The timing to start conveying the paper P is input to the sensor control unit 65 from the conveyance control unit 61. The sensor control unit 65 operates the CIS 201 a predetermined time after the timing rollers 31 start conveying the paper P. The predetermined time is equal to or longer than the time it takes for the paper P to travel from the timing rollers 31 to reach the CIS 201. The sensor control unit 65 outputs the output values ​​output by each of the multiple photoelectric conversion elements 202 to the conveyance position detection unit 69.

[0053] The sensor control unit 65 includes a specific element detection unit 73. The specific element detection unit 73 detects, as a specific element, a photoelectric conversion element 202 among the multiple photoelectric conversion elements 202 that has paper dust D or the like attached to its detection area. Specifically, the specific element detection unit 73 operates the CIS 201 during a period when no paper P is present in the detection area of ​​the multiple photoelectric conversion elements 202. The period when no paper P is present in the detection area of ​​the multiple photoelectric conversion elements 202 is determined based on the timing of starting conveyance of the paper P input from the conveyance control unit 61. From the size of the paper P, the period from when the timing roller 31 starts conveying the paper P until the paper P passes through the CIS 201 can be calculated.

[0054] The specified element detection unit 73 compares the output values ​​output by each of the multiple photoelectric conversion elements 202, and determines as the specified element a photoelectric conversion element 202 that corresponds to an output value different from that of the other photoelectric conversion elements 202. It is clear that the number of photoelectric conversion elements 202 to which paper dust D adheres is smaller than the number of photoelectric conversion elements 202 to which paper dust D does not adhere. Therefore, the photoelectric conversion element 202 that corresponds to an output value that differs from the average output value by more than a predetermined value is determined as the specified element.

[0055] Furthermore, the output value of the photoelectric conversion element 202 when no paper P is present in the detection area of ​​the photoelectric conversion element 202 and the output value of the photoelectric conversion element 202 when paper P is present in the detection area of ​​the photoelectric conversion element 202 may be stored in advance. In this case, the specified element detection unit 73 determines, as the specified element, the photoelectric conversion element 202 corresponding to the output value that is closest to the pre-stored output value from among the multiple photoelectric conversion elements 202. The specified element detection unit 73 outputs identification information that identifies the specified element to the movement control unit 67.

[0056] The movement control unit 67 controls the motor 203 to move the CIS 201. The movement control unit 67 includes a relative position determination unit 75. The relative position determination unit 75 determines the relative position between the CIS 201 and the paper P. The position of the paper P is the position of the end in the Y direction when the paper P is transported along the transport path 39. Furthermore, when the paper P is transported along the transport path 39, the end in the Y direction passes through an allowable range in the Y direction. This allowable range is determined in advance based on the type and width size of the paper P. Therefore, the relative position determination unit 75 determines the position of the paper P to be the end of the allowable range that is farthest from the position sensor 205. The movement control unit 67 determines the position of the CIS 201 at a position where the specific element overlaps in the X direction with the paper P transported along the transport path. Specifically, the position of the CIS 201 is determined so that the specific element is located on the positive side of the Y direction relative to the position of the paper P.

[0057] 4, the position of the CIS 201 is a position moved a distance L1 from the home position. The position of the specific element, in other words, the portion of the CIS 201 where paper dust D is attached, is a position distance L4 away from the end of the CIS 201. A distance L3 by which the CIS 201 is moved is calculated so that distance L4 is greater than distance L2. Note that this example shows a case in which the paper P passes through the end of the allowable range defined in the Y direction that is farthest from the position sensor 205 when the paper P is transported.

[0058] 6, when the position of the CIS 201 is determined by the relative position determination unit 75, the movement control unit 67 moves the CIS 201 to the determined position. The movement control unit 67 outputs the position after the CIS 201 is moved as the sensor position to the transfer position detection unit 69. In the example shown in the lower part of FIG. 4, the sensor position is a value obtained by adding a distance L3 to a distance L1 from the home position.

[0059] If the movement control unit 67 cannot move the CIS 201 to the position of the CIS 201 determined by the relative position determination unit 75, the movement control unit 67 moves the CIS 201 to the home position and outputs a cleaning instruction to the cleaning control unit 71.

[0060] In response to the input of a cleaning instruction, the cleaning control unit 71 controls the cleaning unit 207 to clean the surface of the CIS 201 on which the plurality of photoelectric conversion elements 202 are formed.

[0061] The transport position detection unit 69 detects the position of the Y-direction edge of the paper P transported along the transport path 39 as the medium position. The transport position detection unit 69 receives the transport position from the movement control unit 67 and the output values ​​of each of the multiple photoelectric conversion elements 202 from the sensor control unit 65. Based on the output values ​​of each of the multiple photoelectric conversion elements 202, the transport position detection unit 69 determines the boundary between a first group of photoelectric conversion elements 202 that overlaps with the paper P in the X direction and a second group of photoelectric conversion elements 202 that does not overlap with the paper P in the X direction. The transport position detection unit 69 determines the distance from the edge of the CIS 201 to the boundary position. The transport position detection unit 69 determines the medium position from the transport position of the CIS 201 and the distance from the edge of the CIS 201 to the boundary position. The transport position detection unit 69 outputs the medium position to the transport position notification unit 63.

[0062] The transport position notification unit 63 notifies the image forming unit 3 of the medium position. The image forming unit 3, which receives the medium position, controls the image forming units 20Y, 20M, 20C, and 20K to adjust the Y-direction position of the toner image formed on the intermediate transfer belt 30. If the medium position is deviated from the reference position, the image forming unit 3 moves the position where the toner image is formed in a direction that offsets the deviation. This adjusts the widthwise position of the image formed on the paper P.

[0063] 7 is a flowchart showing an example of the flow of the transport control process. The transport control process is performed by CPU 51 as CPU 51 executes a transport control program stored in ROM 53, HDD 55, or CD-ROM 59. Referring to FIG. 7, CPU 51 included in MFP 1 determines whether a print job has been accepted (step S01). CPU 51 remains in a standby state until a print job is accepted (NO in step S01), and if a print job has been accepted (YES in step S01), the process proceeds to step S02. CPU 51 accepts a print job when communication I / F unit 52 receives a print job from a PC, or when a user operates operation panel 5 to input a print instruction.

[0064] In step S02, variable n is incremented by 1, and the process proceeds to step S03. Variable n is information that identifies one or more pages included in the image data. The image data is included in the print job. The initial value of variable n is 0. In step S03, page n is selected for processing, and the process proceeds to step S04.

[0065] In step S04, the paper position is determined. The paper position is a position that is predetermined with respect to the widthwise size of the paper P transported along the transport path 39. Specifically, based on the printing conditions included in the print job, the CPU 51 identifies one of the paper feed cassettes 35, 35A, and 35C that stores the type of paper P specified by the printing conditions. Furthermore, the CPU 51 determines the widthwise size of the paper P when the paper P is transported from the direction of the paper P stored in the identified cassette. The width direction of the paper P is a direction perpendicular to the transport direction and parallel to the Y direction. The CPU 51 determines the Y-direction position where the edge of the paper P transported along the transport path passes, based on the widthwise size of the paper. The Y-direction edge of the paper P transported along the transport path is transported within an allowable range in the Y direction. The Y-direction position where the edge of the paper P transported along the transport path 39 passes is the farthest position from the position sensor 205 within the allowable range. The farthest position from the position sensor 205 within the allowable range is the upper limit on the positive side of the Y direction.

[0066] In step S05, the specified element is detected, and the process proceeds to step S06. The CPU 51 operates the CIS 201 to acquire the output values ​​of each of the photoelectric conversion elements 202. Then, the CPU 51 detects, as the specified element, a photoelectric conversion element 202 whose output value differs from the output values ​​of the other photoelectric conversion elements 202. For example, the CPU 51 determines, as the specified element, a photoelectric conversion element 202 whose output value differs from the average of the output value by a predetermined value or more. As a result, the photoelectric conversion element 202 in which paper dust D has adhered to the detection area is detected as the specified element. The CIS 201 is operated in a state before the paper P is conveyed, in other words, in a state in which the CIS 201 and the paper P do not overlap in the X direction. Therefore, the output value of the specified element in which paper dust D has adhered to the detection area differs from the output value of a photoelectric conversion element 202 in which paper dust D has not adhered to the detection area.

[0067] In step S06, it is determined whether a specific element has been detected. If a specific element has been detected, the process proceeds to step S07; otherwise, the process proceeds to step S11. In step S07, a relative position is determined. The relative position is the relative position between the CIS 201 and the paper P. The position of the paper P has been determined in step S04. Therefore, the CPU 51 determines the position of the CIS 201 based on the specific element determined in step S06. Specifically, when the CIS 201 and the paper P transported on the transport path 39 overlap in the X direction, the CPU 51 determines the position of the CIS 201 to a position where the specific element overlaps the paper P in the X direction. In the example shown in FIG. 4, the CPU 51 calculates a distance L4 from the end of the CIS 201 on the home position side to the specific element. Then, the CPU 51 acquires the current distance L1 that the CIS 201 has moved from the home position. The position where the sum of distance L4 and distance L1 is greater than distance L5 between the current home position of CIS 201 and the position of paper P is determined as the position to which CIS 201 should be moved. In this case, L3 is calculated as the distance to move CIS 201 from the position at distance L1 from the home position.

[0068] In step S08, it is determined whether the position of CIS 201 determined in step S07 is within the movable range. If CIS 201 is within the movable range, the process proceeds to step S10; otherwise, the process proceeds to step S09. In step S09, CIS 201 is cleaned, and the process proceeds to step S11. CPU 51 drives cleaning unit 207 to clean the surface of CIS 201 on which multiple photoelectric conversion elements 202 are arranged. In step S10, CIS 201 is moved to the position determined in step S07, and the process proceeds to step S11.

[0069] In step S11, the CPU 51 controls the paper feed unit 4 to transport the paper P. As a result, the paper P is transported along the transport path 39, and the paper P and the CIS 201 overlap in the X direction. In step S12, the CPU 51 operates the CIS 201, and the process proceeds to step S13. Then, in step S13, the medium position is detected, and the process proceeds to step S14. The CPU 51 acquires output values ​​of each of the multiple photoelectric conversion elements 202. The multiple photoelectric conversion elements 202 include a first set consisting of multiple elements that overlap with the paper P in the X direction, and a second set consisting of multiple elements that do not overlap with the paper P in the X direction. The output values ​​of the multiple photoelectric conversion elements 202 included in the first set fall within a predetermined range. The output values ​​of the multiple photoelectric conversion elements 202 included in the second set fall within a predetermined range. Therefore, the position of the boundary between the plurality of photoelectric conversion elements 202 included in the first set and the set of the plurality of photoelectric conversion elements 202 included in the second set is detected as the transport position. The transport position is the position of the edge of the paper P in the Y direction.

[0070] In step S14, the medium position is notified, and the process proceeds to step S15. CPU 51 outputs the medium position to image forming unit 3. In image forming unit 3, image forming units 20Y, 20M, 20C, and 20K adjust the positions of the toner images formed on intermediate transfer belt 30 based on the medium position. As a result, the toner image is formed at a position corresponding to paper P located at the medium position, so that even if paper P is shifted in the width direction, the toner image is transferred to the appropriate position on paper P at the nip portion.

[0071] In step S15, it is determined whether or not there is a page to be imaged next. If there is a page to be imaged next, the process returns to step S02; if not, the process ends.

[0072] <First Modification> In the above-described embodiment, the MFP 1 moves the CIS 201 to determine the relative position between the paper P and the CIS 201. Instead of moving the CIS 201, or in addition to moving the CIS 201, the MFP 1 may move the paper P in the Y direction.

[0073] Fig. 8 is a diagram showing an example of a timing roller moving mechanism. Fig. 8 is a diagram showing timing roller 31 viewed from the negative side toward the positive side in the X direction. Referring to Fig. 8, the timing roller moving mechanism includes swing motor 213 and rack 215. Timing roller 31 is held by main roller shaft 214. Main roller shaft 214 is held in the housing of MFP1 in a state where it can rotate relative to the housing of MFP1 and move in the Y direction. Two bearings 216 are rotatably connected to main roller shaft 214 on the outer sides of both ends of timing roller 31, respectively.

[0074] Sub-roller 31A is held by sub-roller shaft 214A. Both ends of sub-roller shaft 214A are held by two bearings 216 so that it can rotate but cannot move in the Y direction. The two bearings 216 hold main roller shaft 214 and sub-roller shaft 214A in a parallel state. This maintains a predetermined distance between timing roller 31 and sub-roller 31A. The two bearings 216 are restricted from rotating around the axis of main roller shaft 214 by restricting members provided on the housing of MFP1. This maintains a constant positional relationship between main roller shaft 214 and sub-roller shaft 214A around the rotation axis.

[0075] The main roller shaft 214 is connected to the drive motor 211 via a drive gear 212. Therefore, when the drive motor 211 operates, the main roller shaft 214 rotates. The rotation of the main roller shaft 214 causes the timing roller 31 to rotate. The timing roller 31 and the sub-roller 31A are in contact with each other, and frictional force generated at the contact area causes the sub-roller 31A to rotate with the rotation of the timing roller 31. Therefore, when the paper P enters between the timing roller 31 and the sub-roller 31A, the paper P is conveyed while being gripped by the timing roller 31 and the sub-roller 31A.

[0076] The rack 215 is connected to the main roller shaft 214 between two flanges provided on the main roller shaft 214 in a state in which it can rotate relative to the main roller shaft 214 but cannot move in the Y direction. The rack 215 has a plurality of teeth of the same shape formed at equal intervals.

[0077] A pinion gear is connected to the swing motor 213. The pinion gear engages with multiple teeth of the rack 215. Therefore, when the swing motor 213 operates, the main roller shaft 214 moves parallel to the Y direction. As the main roller shaft 214 moves in the Y direction, the timing roller 31 and the sub roller 31A move in the Y direction. Therefore, when the swing motor 213 operates while the timing roller 31 and the sub roller 31A are gripping the paper P, the paper P moves in the Y direction as the timing roller 31 and the sub roller 31A move in the Y direction. It is preferable to stop the drive motor 211 while the swing motor 213 is operating. In this case, the timing roller 31 and the sub roller 31A stop rotating and grip the paper P, so the paper P can be moved in the Y direction while being securely gripped.

[0078] FIG. 9 is a diagram illustrating the movement of the timing roller. Note that drive motor 211 and cleaning unit 207 are omitted from FIG. 9. The upper part of FIG. 9 shows a state in which paper dust D is attached to a position of CIS 201 near a portion corresponding to the edge of paper P in the Y direction. The portion of CIS 201 to which paper dust D is attached is close to the edge of paper P in the Y direction. The output value of photoelectric conversion element 202 in the portion to which paper dust D is attached is closer to the output value of photoelectric conversion element 202 in the portion that overlaps with paper P in the X direction than the output value of photoelectric conversion element 202 in the portion that does not overlap with paper P in the X direction. Therefore, from the output values ​​of the multiple photoelectric conversion elements 202 in CIS 201, the position of the portion of CIS 201 to which paper dust D is attached is erroneously detected as the edge of paper P in the Y direction.

[0079] The MFP1 in the first modified example moves the sheet P to a position where the photoelectric conversion elements 202 in the portion of the CIS 201 that overlaps with the paper dust D do not overlap the edge of the sheet P in the Y direction in the X direction. Specifically, as shown in the lower part of FIG. 9 , the timing roller 31 is moved by a distance L6 to move the sheet P to a position where the photoelectric conversion elements 202 in the portion of the CIS 201 that overlaps with the paper dust D overlap with the sheet P in the X direction. As a result, the output value of the photoelectric conversion elements 202 in the portion of the CIS 201 that overlaps with the paper dust D becomes the same as the output value of the photoelectric conversion elements 202 in the portion of the other multiple photoelectric conversion elements 202 that overlap with the sheet P in the X direction. Therefore, the boundary between the first group of the multiple photoelectric conversion elements 202 that detects the sheet P and the second group that does not detect the sheet P is detected as the edge of the sheet P in the Y direction.

[0080] <Second Modification> In the above embodiment, the MFP 1 adjusts the position where an image is formed on the sheet P. The MFP 1 in the second modified example adjusts the position of post-processing of the sheet P in the post-processing device 100.

[0081] 10 is an enlarged view showing the internal configuration of post-processing device 100. Referring to FIG. 10, post-processing device 100 includes punch unit 101, upper guide plate 131, lower guide plate 132, forward / reverse roller pair 136, discharge roller pair 137, detection unit 200A, and discharge tray 138.

[0082] The punch unit 101 includes an inlet 102 for receiving paper on which an image has been formed from the image forming unit 3, and an outlet 103 for discharging the paper.

[0083] The upper guide plate 131 and the lower guide plate 132 face each other in the vertical direction and are arranged with a predetermined gap between them. A part of the transport path along which the paper is transported is formed between the upper guide plate 131 and the lower guide plate 132. The transport path formed between the upper guide plate 131 and the lower guide plate 132 runs from the discharge outlet 103 of the punch unit 101 to a pair of discharge rollers 137. A pair of forward and reverse rollers 136 is arranged in the transport path formed between the upper guide plate 131 and the lower guide plate 132 at a position a predetermined distance away from the discharge outlet 103.

[0084] The forward / reverse roller pair 136 includes two cylindrical rollers. The two rollers are arranged side by side with their respective rotational symmetry axes parallel to each other and are arranged to be rotatable around their respective rotational symmetry axes. The rotation axis of one of the two rollers is biased toward the rotation axis of the other roller. The rotational force of a motor is transmitted to the forward / reverse roller pair 136, causing it to rotate around its rotation axis. The two rollers rotate in opposite directions. The rotational force of the motor may be transmitted to each of the two rollers, or the rotational force of the motor may be transmitted to either one of the rollers.

[0085] A motor that transmits a rotational force to the forward / reverse roller pair 136 rotates the forward / reverse roller pair 136 in either a forward or reverse direction. When the forward / reverse roller pair 136 rotates forward, the forward / reverse roller pair 136 transports the paper in a direction from the punch unit 101 toward the discharge roller pair 137. When the forward / reverse roller pair 136 rotates reversely, the forward / reverse roller pair 136 transports the paper in a direction from the discharge roller pair 137 toward the punch unit 101.

[0086] The discharge roller pair 137 includes two cylindrical rollers. The two rollers are arranged side by side with their respective rotational symmetry axes parallel to each other and are arranged to be rotatable around their respective rotational symmetry axes. The rotational axis of one of the two rollers is biased toward the rotational axis of the other roller. The rotational force of a motor is transmitted to the discharge roller pair 137, causing it to rotate around its rotational axis. The two rollers rotate in opposite directions. The rotational force of the motor may be transmitted to each of the two rollers, or to just one of them.

[0087] Detector 200A is disposed between forward / reverse roller pair 136 and discharge roller pair 137 in the conveyance path formed between upper guide plate 131 and lower guide plate 132. The configuration of detector 200A is the same as that of detector 200 described above, and therefore description thereof will not be repeated here.

[0088] A sheet discharged from the image forming unit 3 enters the punch unit 101 from the receiving port 102, enters a conveyance path formed between an upper guide plate 131 and a lower guide plate 132 via the discharge port 103, and reaches the forward / reverse roller pair 136. The sheet that reaches the forward / reverse roller pair 136 is conveyed by the forward / reverse roller pair 136. While the sheet P passes through the detection unit 200A, the detection unit 200A detects the position of the edge of the sheet P in the Y direction. The forward / reverse roller pair 136 rotates forward and then reversely, thereby positioning the sheet in the punch unit 101 and punching holes therein. Before the sheet is positioned by the punch unit 101, the position at which the punch unit 101 punches holes is adjusted based on the position of the edge of the sheet P in the Y direction detected by the detection unit 200A.

[0089] Thereafter, the forward / reverse roller pair 136 rotates forward, causing the sheet to reach the discharge roller pair 137. The sheet conveyed by the discharge roller pair 137 is discharged onto the paper discharge tray 138.

[0090] Fig. 11 is a first cross-sectional view showing an enlarged view of the punch unit and its vicinity. Referring to Fig. 11, the punch unit 101 includes an upper guide plate 131, a lower guide plate 132, a regulating member 110, a punch mechanism 140, and a dust storage unit 145 arranged below the punch mechanism 140. A plurality of regulating members 110 are arranged side by side in the Y direction. The dust storage unit 145 is a box in the shape of a rectangular parallelepiped with an open top. The dust storage unit 145 stores the dust generated when the punch mechanism 140 punches a hole in a sheet of paper, which falls from the punch mechanism 140.

[0091] The punch mechanism 140 is a processing unit that punches a sheet and includes an upper punch member 149 and an opposing plate 132a. The upper punch member 149 and the opposing plate 132a are disposed opposite each other across the sheet conveyance path. The upper punch member 149 is disposed above the conveyance path, and the opposing plate 132a is disposed below the conveyance path. The upper punch member 149 includes multiple cylindrical punch shafts 141 with punch blades formed at their tips, a cam plate 143 with a cam groove formed therein, and a drive mechanism that moves the cam plate 143. Each of the multiple punch shafts 141 is installed so that its axis is parallel to one direction and it can move back and forth in a direction parallel to the one direction. In this embodiment, the one direction is the vertical direction, and four punch shafts 141 are installed. All four punch shafts 141 have the same configuration. A sliding member extending perpendicular to the axis is coupled to the punch shaft 141. The sliding member has a cylindrical shape, and the axis of rotational symmetry of the sliding member is perpendicular to the axis of the punch shaft 141.

[0092] The cam plate 143 is a flat plate having a reference surface parallel to the axis of the punch shaft 141, and is formed with a cam groove perpendicular to the reference surface. A sliding member is inserted into the cam groove formed in the cam plate 143. A drive mechanism causes the cam plate 143 to reciprocate in a horizontal direction parallel to the axis of the punch shaft 141, causing the sliding member coupled to the punch shaft 141 to slide within the cam groove. This causes the punch shaft 141 to reciprocate in a direction parallel to the axis. In this embodiment, the punch shaft 141 is a movable part whose axis reciprocates in a direction parallel to the vertical direction. As the punch shaft 141 descends, the opposing plate 132a ascends and supports the sheet, and the punch shaft 141 penetrates through a through-hole 142 formed in the opposing plate 132a, thereby perforating the sheet.

[0093] The upper guide plate 131 and the lower guide plate 132 face each other in the vertical direction and are arranged with a predetermined gap between them. A part of the transport path along which the paper is transported is formed between the upper guide plate 131 and the lower guide plate 132. The upper guide plate 131 and the lower guide plate 132 extend from the receiving opening 102 of the punch unit 101 to the discharge opening 103. An opening is formed in the upper guide plate 131 at a position facing the punch shaft 141, allowing the punch shaft 141 to enter.

[0094] The multiple regulating members 110 are arranged side by side in the Y direction at a predetermined distance apart, closer to the receiving port 102 than the punch shaft 141 in a side view. The regulating members 110 have bearings 112, and are attached rotatably around the rotation shaft 123 by connecting the bearings 112 to the rotation shaft 123. The rotation shaft 123 is fixed to the frame of the punch unit 101 so as to be parallel to the Y direction.

[0095] Figure 12 is a second cross-sectional view showing an enlarged view of the regulating member and its vicinity. Figure 12 shows regulating member 110 in the second position. Referring to Figure 12, when regulating member 110 is in the second position, a gap through which paper P can pass is formed between upper guide plate 131 and locking surface 117 of regulating member 110. As a result, paper P is transported in the direction of arrow a1 to forward / reverse roller pair 136.

[0096] 13 is a third enlarged cross-sectional view of the regulating member and its vicinity. Referring to FIG. 13, when the rear end of the paper sheet P passes through regulating member 110, regulating member 110 no longer receives force from the paper sheet P, so it rotates in the direction of arrow a3 under its own weight and returns to the first position.

[0097] After the sheet P passes through the regulating member 110, the forward / reverse roller pair 136 rotates in the opposite direction, transporting the sheet in the direction indicated by the arrow a2 until the sheet abuts against the contact surface 113. When the regulating member 110 is in the first position, the regulating member 110 blocks the transport path. Therefore, the leading edge of the sheet is guided by the upper guide plate 131 or the lower guide plate 132 and abuts against the contact surface 113. This positions the sheet P. Since the distance between the contact surface 113 and the punch shaft 141 in the X direction is predetermined, the sheet P is positioned relative to the punch shaft 141. In this state, the punch shaft 141 descends.

[0098] Fig. 14 is a fourth cross-sectional view showing an enlarged view of the regulating member and its vicinity. Referring to Fig. 14, while opposing plate 132a is raised to support the paper sheet, punch shaft 141 descends, penetrating paper sheet P and through-hole 142 formed in opposing plate 132a. This perforates paper sheet P, and cutting chips fall downward.

[0099] In MFP1 in the second modified example, detection unit 200A is disposed between forward / reverse roller pair 136 and discharge roller pair 137 in a transport path formed between upper guide plate 131 and lower guide plate 132 of post-processing device 100. Sheet P, on which an image has been formed by image forming unit 3, enters post-processing device 100 from receiving port 102, reaches forward / reverse roller pair 136, and is transported by forward / reverse roller pair 136 toward discharge roller pair 137. At this time, while sheet P passes detection unit 200A, detection unit 200A detects the position of the edge of sheet P in the Y direction. As forward / reverse roller pair 136 rotates in the reverse direction while gripping sheet P, sheet P is transported toward punch unit 101. As punch unit 101 moves in the Y direction during this time, the position at which punch unit 101 punches holes in sheet P is adjusted. Then, with sheet P positioned by restriction member 110, punch unit 101 forms holes. In this way, before the paper sheet P is positioned by the punch unit 101, the position at which the punch unit 101 punches a hole is adjusted based on the medium position in the Y direction of the edge of the paper sheet P detected by the detection section 200A.

[0100] In the second modified example, as in the above-described embodiment, the detection unit 200A detects the specific element when no paper P is present in the detection area. Then, the CIS 201 is moved to a position where the detection area of ​​the specific element overlaps with the paper P. Therefore, even if paper dust D adheres to the CIS 201, the detection unit 200A can accurately detect the position of the edge in the Y direction of the paper P being transported along the transport path.

[0101] In the second modified example, the punch mechanism 140 has been described as an example of post-processing, but the post-processing is not limited to this. The post-processing may include, for example, a stapling process in which staples are driven into the paper P, a bending process in which the paper P is folded, etc.

[0102] <Third Modification> The MFP1 in the second modified example moves the CIS 201 to determine the relative position between the sheet P and the CIS 201 in the post-processing device 100. As in the first modified example, the MFP1 may move the sheet P in the Y direction instead of or in addition to moving the CIS 201.

[0103] <Fourth Modification> In the embodiment described above, when a print job includes multiple pages, the CPU 51 causes the conveyance control unit 61 to continuously convey multiple sheets of paper P. The conveyance control unit 61 conveys two sheets of paper P with a predetermined interval between them. The specific element detection unit 73 detects the specific element between the time when the previous sheet of paper P being continuously conveyed passes through the CIS 201 and the time when the next sheet of paper P reaches the CIS 201.

[0104] When a print job includes multiple pages, the CPU 51 may cause the specific element detection unit 73 to detect the specific element before the paper P of the first page reaches the CIS 201. In this case, it is not necessary to detect the specific element before the paper P of the second or subsequent pages passes the CIS 201. In this case, the specific element detected before the paper P of the first page reaches the CIS 201 is considered valid for the paper P of the second or subsequent pages.

[0105] <Fifth Modification> The timing for CIS201 to detect the edge of paper P may be after movement control unit 67 controls motor 203 to move CIS201. The specific element detection unit 73 detects the position of the specific element before paper P passes through the detection area of ​​CIS201, and movement control unit 67 moves CIS201. Even if paper P passes through the detection area of ​​CIS201 while movement control unit 67 is moving CIS201, CIS201 can detect the edge of paper P as long as paper P is present in the detection area after movement control unit 67 has moved CIS201.

[0106] <Summary of implementation form> (Item 1) A conveying unit that conveys a recording medium in a conveying direction along a conveying path; a sensor including a plurality of detection elements each having a detection area facing a first direction, the plurality of detection elements being arranged in a second direction intersecting the conveying direction and the first direction; a movement control unit that moves the sensor and the recording medium relative to each other in the second direction;

[0107] According to this aspect, a sensor having a plurality of detection elements with detection areas facing a first direction intersecting the transport direction and a recording medium are moved relative to each other in a second direction. The plurality of detection elements are arranged in a second direction intersecting both the transport direction and the first direction. Therefore, any of the plurality of detection elements of the sensor can be made to correspond to an end, in the second direction, of the recording medium transported along the transport path in the transport direction. Therefore, a detection element other than a detection element that has become unable to detect the recording medium in its detection area due to the adhesion of paper dust or the like can be used to detect the end of the recording medium in the second direction. As a result, a recording medium transport device can be provided that can accurately detect the position of the recording medium transported along the transport path.

[0108] (Item 2) A specific element detection unit that detects a specific element based on the outputs of the plurality of detection elements when the recording medium is not present in the plurality of detection areas, and detects a detection element whose output is different from other detection elements as the specific element. Item 2. The recording medium conveying device according to item 1, further comprising a relative position determining unit that determines a relative position between the sensor and the recording medium in response to detection of the specific element.

[0109] According to this aspect, a specific element whose output differs from that of the other detection elements when no recording medium is present in the detection area is detected, and the relative position of the sensor and the recording medium is determined in response to the detection of the specific element. Therefore, it is possible to detect the edge of the recording medium in the second direction using a detection element other than a detection element that has become unable to detect the recording medium in the detection area due to paper dust or the like adhering thereto.

[0110] (Item 3) The recording medium transport device according to Item 2, wherein the relative position determination unit determines the relative position as a position where the specific element overlaps with the recording medium transported on the transport path in the first direction.

[0111] According to this aspect, the position where the specific element overlaps in the first direction with the recording medium transported along the transport path is determined as the relative position. The output of the specific element is similar to the output of a detection element among the multiple detection elements that overlaps with the recording medium in the first direction, and is different from the output of a detection element among the multiple detection elements that does not overlap with the recording medium in the first direction. Because the specific element overlaps with the recording medium transported along the transport path in the first direction, the specific element can be included in a set of detection elements among the detection elements that overlap with the recording medium in the first direction. Therefore, the other multiple detection elements among the multiple detection elements other than the specific element can be separated into a set of detection elements that overlap with the recording medium in the first direction and a set of detection elements that do not overlap with the recording medium in the first direction. The boundary between the two sets can then be detected as the edge of the recording medium in the second direction.

[0112] (Item 4) A recording medium conveying device as described in Item 2 or 3, wherein when the specific element detection unit detects multiple specific elements, the relative position determination unit determines the relative position to be the position where all of the multiple specific elements overlap in the first direction with the recording medium being conveyed along the conveying path.

[0113] According to this aspect, the relative position is determined to be the position where all of the plurality of specific elements overlap in the first direction with the recording medium transported along the transport path. A detection element located between the plurality of specific elements is positioned to overlap in the first direction with the recording medium. Therefore, among the plurality of detection elements, a plurality of detection elements other than the plurality of specific elements and the detection elements located between the plurality of specific elements can be separated into a set of detection elements that overlap in the first direction with the recording medium and a set of detection elements that do not overlap in the first direction with the recording medium. The boundary between the two sets can then be detected as the edge of the recording medium in the second direction.

[0114] (Item 5) A cleaning unit that cleans the plurality of detection elements; 5. The recording medium conveying device according to any one of items 2 to 4, further comprising a cleaning control unit that causes the cleaning unit to clean the plurality of detection elements when the movement control unit is unable to move the sensor and the recording medium relative to the relative position determined by the relative position determination unit.

[0115] According to this aspect, when the sensor and the recording medium cannot be moved to the determined relative position, the plurality of detection elements are cleaned, thereby reducing the number of cleaning operations.

[0116] (Item 6) A recording medium transport device described in any of Items 2 to 5, wherein when multiple recording media are transported continuously by the transport unit, the relative position determination unit determines the relative position before each of the multiple recording media enters the detection area, or before the first recording medium enters the detection area.

[0117] According to this aspect, the relative positions of the plurality of consecutive recording media are determined before each of the consecutive recording media enters the detection area, allowing for accurate detection of the specific element. Therefore, the edge of each of the consecutive recording media in the second direction can be detected. Furthermore, if the lengths of the consecutively transported consecutive recording media in the second direction are the same, the positions of the edges of the consecutively transported consecutive recording media in the second direction will be similar. Therefore, by detecting the edge of the first of the consecutive recording media in the second direction, the number of times the sensor and the recording media need to be moved relative to each other can be reduced.

[0118] (Item 7) A recording medium transport device according to any one of items 2 to 6, further comprising a transport position detection unit that detects the media position in the second direction of the recording medium being transported along the transport path based on the output of the sensor after the movement control unit has completed movement of the sensor and the recording medium to the relative position.

[0119] According to this aspect, the position of the recording medium in the second direction being transported along the transport path is detected based on the output of the sensor after the movement of the sensor and the recording medium to the relative position is completed, so that the edge of the recording medium in the second direction can be accurately detected.

[0120] (Item 8) The recording medium transport device according to item 7, an image forming unit that forms an image on the recording medium conveyed by the conveying unit, The image forming device, wherein the image forming unit determines a position of an image to be formed on the recording medium based on the medium position.

[0121] According to this aspect, the position of the image to be formed on the recording medium is determined based on the medium position, so that an image forming device can be provided that is capable of forming an image at an appropriate position on the recording medium.

[0122] (Item 9) The recording medium transport device according to item 7, a post-processing unit that processes the recording medium transported by the transport unit, The post-processing device is configured to determine a position for processing the recording medium based on the medium position.

[0123] According to this aspect, the position for processing the recording medium is determined based on the medium position, so that it is possible to provide a post-processing device that can process the recording medium at an appropriate position.

[0124] (Item 10) A transport control method executed in a recording medium transport device, comprising: The recording medium transport device includes a transport unit that transports the recording medium in a transport direction along a transport path; a sensor in which a plurality of detection elements each having a detection area extending in a first direction are arranged in a second direction intersecting the transport direction and the first direction; a movement control unit that moves the sensor and the recording medium relative to each other in the second direction, a specific element detection step of detecting a specific element from among the plurality of detection elements, the specific element having an output different from that of the other detection elements; a relative position determining step of determining a relative position between the sensor and the recording medium in response to detection of the specific element.

[0125] According to this aspect, it is possible to provide a transport control method that is capable of accurately detecting the position of a recording medium transported along a transport path.

[0126] (Item 11) A transport control program executed by a computer that controls a recording medium transport device, The recording medium transport device includes a transport unit that transports the recording medium in a transport direction along a transport path; a sensor in which a plurality of detection elements each having a detection area extending in a first direction are arranged in a second direction intersecting the transport direction and the first direction; a movement control unit that moves the sensor and the recording medium relative to each other in the second direction, a specific element detection step of detecting a specific element from among the plurality of detection elements, the specific element having an output different from that of the other detection elements; a relative position determining step of determining a relative position between the sensor and the recording medium in response to detection of the specific element.

[0127] According to this aspect, it is possible to provide a transport control program that can accurately detect the position of a recording medium transported along a transport path.

[0128] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0129] 1 MFP, 2 document reading unit, 3 image forming unit, 4 paper feed unit, 5 operation panel, 20Y, 20M, 20C, 20K image forming units, 30 intermediate transfer belt, 31 timing roller, 31A sub-roller, 35, 35A, 35C paper feed cassette, 36, 36A take-out roller, 37 paper feed roller, 39 transport path, 50 main circuit, 51 CPU, 52 communication I / F unit, 53 ROM, 54 RAM, 55 HDD, 56 facsimile unit, 58 external storage device, 59 CD-ROM, 61 transport control unit, 63 transport position notification unit, 65 sensor control unit, 67 movement control unit, 69 transport position detection unit, 71 cleaning control unit, 73 specific element detection unit, 75 relative position determination unit, 100 post-processing unit, 101 punch unit, 200, 200A Detecting unit, 202 photoelectric conversion element, 203 motor, 205 position sensor, 207 cleaning unit, 211 drive motor, 212 drive gear, 213 swing motor, 214 main roller shaft, 214A sub-roller shaft, 215 rack, 216 bearing unit, D paper dust, P paper.

Claims

1. a conveying unit that conveys the recording medium in a conveying direction along a conveying path; a sensor including a plurality of detection elements each having a detection area facing a first direction, the plurality of detection elements being arranged in a second direction intersecting the conveying direction and the first direction; a movement control unit that moves the sensor and the recording medium relative to each other in the second direction;

2. a specific element detection unit that detects a detection element whose output is different from other detection elements as a specific element based on outputs of the plurality of detection elements when the recording medium is not present in the plurality of detection areas; 2. The recording medium transport device according to claim 1, further comprising a relative position determination unit that determines a relative position between the sensor and the recording medium in response to detection of the specific element.

3. The recording medium transport device according to claim 2 , wherein the relative position determination unit determines the relative position as a position where the specific element overlaps with the recording medium transported on the transport path in the first direction.

4. The recording medium conveying device of claim 2, wherein when the specific element detection unit detects multiple specific elements, the relative position determination unit determines the relative position to be a position where all of the multiple specific elements overlap in the first direction with the recording medium being conveyed along the conveying path.

5. a cleaning unit that cleans the plurality of detection elements; 3. The recording medium transport device of claim 2, further comprising a cleaning control unit that causes the cleaning unit to clean the plurality of detection elements when the movement control unit is unable to move the sensor and the recording medium relative to the relative position determined by the relative position determination unit.

6. 3. The recording medium transport device according to claim 2, wherein the relative position determination unit determines the relative position before each of the recording media enters the detection area, or before the first recording medium enters the detection area, when the recording media are transported continuously by the transport unit.

7. A recording medium transport device as described in any one of claims 2 to 6, further comprising a transport position detection unit that detects the medium position in the second direction of the recording medium being transported along the transport path based on the output of the sensor after the movement control unit has completed movement of the sensor and the recording medium to the relative position.

8. a recording medium transport device according to claim 7; an image forming unit that forms an image on the recording medium conveyed by the conveying unit, The image forming device, wherein the image forming unit determines a position of an image to be formed on the recording medium based on the medium position.

9. a recording medium transport device according to claim 7; a post-processing unit that processes the recording medium transported by the transport unit, The post-processing device, wherein the post-processing unit determines a position for processing the recording medium based on the medium position.

10. A transport control method executed in a recording medium transport device, comprising: The recording medium transport device includes a transport unit that transports the recording medium in a transport direction along a transport path; a sensor in which a plurality of detection elements each having a detection area extending in a first direction are arranged in a second direction intersecting the conveying direction and the first direction; a movement control unit that moves the sensor and the recording medium relative to each other in the second direction, a specific element detecting step of detecting a specific element from among the plurality of detecting elements, the specific element having an output different from that of the other detecting elements; a relative position determining step of determining a relative position between the sensor and the recording medium in response to detection of the specific element.

11. A transport control program executed by a computer that controls a recording medium transport device, The recording medium transport device includes a transport unit that transports the recording medium in a transport direction along a transport path; a sensor in which a plurality of detection elements each having a detection area extending in a first direction are arranged in a second direction intersecting the conveying direction and the first direction; a movement control unit that moves the sensor and the recording medium relative to each other in the second direction, a specific element detecting step of detecting a specific element from among the plurality of detecting elements, the specific element having an output different from that of the other detecting elements; a relative position determining step of determining a relative position between the sensor and the recording medium in response to detection of the specific element.

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