Medium conveying device, control method, and control program

Abstract

To provide a medium conveyance device, control method and control program which can more accurately determine whether or not multi-feeding of media has occurred.SOLUTION: A medium conveyance device comprises: a conveyance unit which conveys a medium; a width detection unit which detects a width in a direction orthogonal to a conveyance direction of the medium conveyed by the conveyance unit; an overlap detection unit which detects an overlap of the media conveyed by the conveyance unit; and a control unit which determines whether or not to execute processing against abnormality caused by multi-feeding, on the basis of the width of the medium obtained on the basis of the detection result of the width detection unit and a detection result of the overlap detection unit. The control unit determines an overlap detection width being a width range where the media are inferred to overlap each other in the direction orthogonal to the conveyance direction of the medium on the basis of the detection result of the overlap detection unit, and executes the processing against the abnormality when the width of the medium is equal to the overlap detection width.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a medium transport device, a control method, and a control program, and more particularly to a medium transport device, a control method, and a control program that determine whether or not a double feed of media has occurred. [Background technology]

[0002] Generally, media transport devices such as scanners have the ability to detect whether a double feed, in which multiple media are transported overlapping each other, has occurred, and automatically stop transporting the media when a double feed occurs.

[0003] For example, a document feeder has been disclosed in which a multi-feed detection sensor, which detects multi-feeding of documents when documents are transported overlapping each other, moves back and forth in a direction perpendicular to the document transport direction, and determines whether a document has been multi-fed based on a multi-feed detection signal detected by the multi-feed detection sensor (see Patent Document 1). This document feeder determines that a document has been multi-fed when it detects a multi-feed detection signal in a width direction perpendicular to the document transport direction that is equal to or greater than a predetermined value.

[0004] Also disclosed is a medium transport device that includes a first sensor located at one end of a transport path for the medium, which detects the passage of the medium and double feed, and a second sensor located at the other end of the transport path, which detects the passage of the medium and double feed (see Patent Document 2). This medium transport device determines whether or not double feed of the medium is occurring based on the detection results of the first and second sensors. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-281777 [Patent Document 2] Japanese Patent Application Publication No. 2019-193219 Summary of the Invention [Problem to be solved by the invention]

[0006] It is desirable for a medium transport device to be able to more accurately determine whether or not a double feed of media has occurred.

[0007] An object of the present invention is to provide a medium transport device, a control method, and a control program that can more accurately determine whether or not a multi-feed of media has occurred. [Means for solving the problem]

[0008] A medium transport device according to one aspect of the present invention includes a transport unit that transports a medium, a width detection unit that detects the width of the medium transported by the transport unit in a direction perpendicular to the transport direction, an overlap detection sensor that detects a detection value corresponding to an overlap of the medium transported by the transport unit, and a detection result of the width detection unit. Achievement and a control unit that executes abnormal processing due to double feeding based on the detection result of the overlap detection sensor, If the width of the medium is larger than the overlap width in the direction perpendicular to the medium transport direction and the overlap length in the medium transport direction is longer than a predetermined length, an abnormality process is executed; The width of the medium Overlap Width Bigger and overlap length but Predetermined length twist If it's short , no abnormality processing is performed. In addition, a medium conveying device according to one aspect of the present invention includes a conveying unit that conveys a medium, a width detection unit that detects the width of the medium conveyed by the conveying unit in a direction perpendicular to the conveying direction, an overlap detection sensor that detects a detection value corresponding to the overlap of the medium conveyed by the conveying unit, and a control unit that executes abnormality processing due to double feeding based on the detection results of the width detection unit and the detection results of the overlap detection sensor, wherein the control unit executes abnormality processing when the width of the medium is greater than the overlap width in the direction perpendicular to the conveying direction of the medium and the detection value indicates that two media are overlapping without being attached, and does not execute abnormality processing when the width of the medium is greater than the overlap width and the detection value indicates that a sticker is attached to the medium.

[0009] A control method according to one aspect of the present invention is a control method for a medium transport device having a transport unit that transports a medium, a width detection unit that detects the width of the medium transported by the transport unit in a direction perpendicular to the transport direction, and an overlap detection sensor that detects a detection value corresponding to an overlap of the medium transported by the transport unit, the control method comprising: Achievement Based on the detection result of the overlap detection sensor, the system executes abnormal processing due to the double feed. If the width of the medium is larger than the overlap width in the direction perpendicular to the medium transport direction and the overlap length in the medium transport direction is longer than a predetermined length, an abnormality process is executed; The width of the medium Overlap Width Bigger and overlap length but Predetermined length twist If it's short , no abnormality processing is performed. Furthermore, a control method according to one aspect of the present invention is a control method for a medium transport device having a transport unit that transports media, a width detection unit for detecting the width of the media transported by the transport unit in a direction perpendicular to the transport direction, and an overlap detection sensor that detects a detection value corresponding to the overlap of the media transported by the transport unit, and executes abnormal processing due to double feeding based on the detection results of the width detection unit and the detection results of the overlap detection sensor, and in executing the abnormal processing, if the width of the media is greater than the overlap width in the direction perpendicular to the transport direction of the media and the detection value indicates that two media are overlapping without being attached, executes abnormal processing, and if the width of the media is greater than the overlap width and the detection value indicates that a sticker is attached to the media, does not execute abnormal processing.

[0010] A control program according to one aspect of the present invention is a control program for a medium transport device having a transport unit that transports a medium, a width detection unit that detects a width of the medium transported by the transport unit in a direction perpendicular to the transport direction, and an overlap detection sensor that detects a detection value corresponding to an overlap of the medium transported by the transport unit, Achievement and causing the medium conveying device to execute abnormal processing due to the double feeding based on the detection result of the overlap detection sensor, and If the width of the medium is larger than the overlap width in the direction perpendicular to the medium transport direction and the overlap length in the medium transport direction is longer than a predetermined length, an abnormality process is executed; The width of the medium Overlap Width Bigger and overlap length but Predetermined length twist If it's short , no abnormality processing is performed. Furthermore, a control program according to one aspect of the present invention is a control program for a medium transporting device having a transporting unit that transports a medium, a width detection unit that detects the width of the medium transported by the transporting unit in a direction perpendicular to the transport direction, and an overlap detection sensor that detects a detection value corresponding to the overlap of the medium transported by the transporting unit, and causes the medium transporting device to execute abnormal processing due to double feeding based on the detection results of the width detection unit and the detection results of the overlap detection sensor, and in executing the abnormal processing, if the width of the medium is greater than the overlap width in the direction perpendicular to the transport direction of the medium and the detection value indicates that two media are overlapping without being attached, the abnormal processing is executed, and if the width of the medium is greater than the overlap width and the detection value indicates that a sticker is attached to the medium, the abnormal processing is not executed. [Effects of the Invention]

[0011] According to the present invention, the medium conveying device, the control method, and the control program are capable of determining with higher accuracy whether or not a multifeed of media has occurred. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a perspective view showing a medium conveying device 100 according to an embodiment. [Figure 2] 2 is a diagram for explaining a transport path inside the medium transport device 100. FIG. [Figure 3] FIG. 10 is a schematic diagram for explaining the arrangement of ultrasonic sensors 115 and the like. [Figure 4] 1 is a block diagram showing a schematic configuration of a medium conveying device 100. FIG. [Figure 5] FIG. 2 is a diagram showing a schematic configuration of a storage device 140 and a processing circuit 150. [Figure 6] 10 is a flowchart illustrating an example of the operation of a medium reading process. [Figure 7] (A) shows an example of a medium image, and (B) is an example of a graph showing the luminance value of each pixel in a specific line image within the medium image. [Figure 8] 10A to 10D are diagrams illustrating how to calculate the overlap detection width. [Figure 9] 10 is a flowchart illustrating an example of the operation of an overlap determination process. [Figure 10] 10A and 10B are schematic diagrams for explaining the technical significance of determining whether or not a multifeed of media has occurred based on the overlap detection width. [Figure 11] 10A and 10B are schematic diagrams for explaining other means for detecting the width of the medium. [Figure 12] FIG. 10 is a schematic diagram for explaining still another means for detecting the width of the medium. [Figure 13] FIG. 10 is a diagram showing a schematic configuration of another processing circuit 250. DETAILED DESCRIPTION OF THE INVENTION

[0013] A medium transport device according to one aspect of the present invention will be described below with reference to the drawings. However, please note that the technical scope of the present invention is not limited to the embodiments described therein, but extends to the inventions set forth in the claims and their equivalents.

[0014] FIG. 1 is a perspective view showing a medium conveying device 100 according to an embodiment configured as an image scanner. The medium conveying device 100 conveys and captures an image of a medium, which is an original document. The medium may be paper, a card, a booklet, or the like. Examples of paper include thin paper or thick paper. Examples of booklets include passports or bankbooks. The medium may also include media with labels (stickers) or small pieces of paper (photographs, clippings, postage stamps, revenue stamps, etc.) attached thereto. The medium conveying device 100 may be a facsimile, a copier, a multifunction printer (MFP), or the like. Note that the conveyed medium may not be an original document but may be a print target or the like, and the medium conveying device 100 may be a printer or the like.

[0015] The medium conveying device 100 includes a lower housing 101, an upper housing 102, a loading table 103, an ejection table 104, an operation device 105, a display device 106, and the like.

[0016] The upper housing 102 is disposed in a position that covers the top surface of the medium conveying device 100, and is engaged with the lower housing 101 by a hinge so that it can be opened and closed when a medium becomes jammed or when cleaning the inside of the medium conveying device 100, for example.

[0017] The top surface of lower housing 101 forms lower guide 107a of the medium transport path, and the bottom surface of upper housing 102 forms upper guide 107b of the medium transport path. In Figure 1, arrow A1 indicates the medium transport direction. Hereinafter, "upstream" refers to the upstream side of medium transport direction A1, and "downstream" refers to the downstream side of medium transport direction A1.

[0018] The mounting table 103 engages with the lower housing 101 so that the medium to be transported can be placed thereon. The mounting table 103 has a mounting surface 103a on which the medium is placed. A first side guide 109a and a second side guide 109b are provided on the mounting surface 103a. The first side guide 109a and the second side guide 109b regulate the position of the medium in the width direction A2. Hereinafter, the first and second side guides 109a, 109b may be collectively referred to as side guides 109. Each side guide 109a, 109b is provided so as to be movable in the width direction A2, which is perpendicular to the medium transport direction of the mounting table 103. Each side guide 109a, 109b has a predetermined height in the height direction A3 and regulates the width direction of the medium placed on the mounting table 103. The first side guide 109a and the second side guide 109b are movably provided so as to be disposed in positions symmetrical with respect to the center position on the mounting table 103 in the width direction A2 perpendicular to the medium transport direction. Alternatively, one of the first side guide 109a and the second side guide 109b may be fixed to a position on one end side of the mounting table 103 in the width direction A2 perpendicular to the medium transport direction, and the other may be movably provided according to the width of the medium.

[0019] The ejection platform 104 is engaged with the lower housing 101 so as to be able to hold the ejected media.

[0020] The operation device 105 has input devices such as buttons and an interface circuit for acquiring signals from the input devices, accepts input operations by a user, and outputs operation signals in response to the user's input operations. The display device 106 has a display such as a liquid crystal display, an organic EL (Electro-Luminescence) display, or the like, and an interface circuit for outputting image data to the display, and displays the image data on the display.

[0021] FIG. 2 is a diagram for explaining the transport path inside the medium transport device 100. As shown in FIG.

[0022] The transport path inside the medium transport device 100 includes a contact sensor 111, a feed roller 112, a brake roller 113, a medium sensor 114, an ultrasonic transmitter 115a, an ultrasonic receiver 115b, a first transport roller 116, a second transport roller 117, a first image capture device 118a, a second image capture device 118b, a third transport roller 119, and a fourth transport roller 120. The feed roller 112, the brake roller 113, the first transport roller 116, and the second transport roller 117 are examples of a transport unit that transports the medium. Note that the number of each roller is not limited to one, and there may be multiple rollers. Hereinafter, the first image capture device 118a and the second image capture device 118b may be collectively referred to as the image capture device 118.

[0023] The contact sensor 111 is disposed upstream of the feed roller 112 and the brake roller 113. The contact sensor 111 detects contact with the medium, thereby detecting whether or not a medium is placed on the placement table 103. The contact sensor 111 generates and outputs a first medium signal whose signal value changes depending on whether or not a medium is placed on the placement table 103.

[0024] The feed roller 112 is provided in the lower housing 101 and feeds the media placed on the placement table 103 from the bottom up. The brake roller 113 is provided in the upper housing 102 and is disposed opposite the feed roller 112.

[0025] The media sensor 114 is located downstream of the feed roller 112 and the brake roller 113 and upstream of the first conveyor roller 116 and the second conveyor roller 117. In particular, the media sensor 114 is located between the feed roller 112 and the ultrasonic transmitter 115a and the ultrasonic receiver 115b in the media conveyance direction A1. The media sensor 114 detects whether a medium is present at that position. The media sensor 114 includes a light emitter and a light receiver provided on one side of the media conveyance path, and a reflecting member (not shown) such as a mirror provided opposite the light emitter and the light receiver across the conveyance path. The light emitter emits light toward the conveyance path. Meanwhile, the light receiver receives light emitted by the light emitter and reflected by the reflecting member, and generates and outputs a second media signal, which is an electrical signal corresponding to the intensity of the received light. When a medium is present at the position of the medium sensor 114, the light emitted by the light emitter is blocked by the medium, and therefore the signal value of the second medium signal changes depending on whether or not a medium is present at the position of the medium sensor 114. The light emitter and the light receiver may be positioned opposite each other across the transport path, and the reflecting member may be omitted.

[0026] The ultrasonic transmitter 115a and the ultrasonic receiver 115b are disposed downstream in the medium conveying direction A1 relative to the feed roller 112 and the brake roller 113 and upstream in the medium conveying direction A1 relative to the first conveying roller 116 and the second conveying roller 117. The ultrasonic transmitter 115a and the ultrasonic receiver 115b are disposed near the medium conveying path, facing each other across the conveying path. The ultrasonic transmitter 115a is capable of outputting ultrasonic waves. Meanwhile, the ultrasonic receiver 115b receives ultrasonic waves emitted by the ultrasonic transmitter 115a that have passed through the medium, and generates and outputs an ultrasonic signal, which is an electrical signal corresponding to the received ultrasonic waves. Hereinafter, the ultrasonic transmitter 115a and the ultrasonic receiver 115b may be collectively referred to as the ultrasonic sensor 115. The ultrasonic sensor 115 detects the transmission intensity of ultrasonic waves that have passed through the medium. The ultrasonic sensor 115 is an example of an overlap detector, and detects an overlap of the media being transported by the transport unit in a detection area, which is an area on the media passing over the ultrasonic receiver 115b.

[0027] The first conveying roller 116 and the second conveying roller 117 are disposed downstream of the feed roller 112 and the brake roller 113 in the medium conveying direction A1 and upstream of the imaging device 118 in the medium conveying direction A1.

[0028] The first imaging device 118a is disposed downstream of the first conveyance roller 116 and the second conveyance roller 117 in the medium conveyance direction A1. The first imaging device 118a has a line sensor based on a CIS (Contact Image Sensor) of a 1:1 optical system type having CMOS (Complementary Metal Oxide Semiconductor) imaging elements linearly arranged in the main scanning direction. Here, the main scanning direction is a direction perpendicular to the medium conveyance direction. The line sensor is an example of an imaging sensor that images the medium. The first imaging device 118a also has a light source that irradiates light toward the conveyed medium, a lens that forms an image on the imaging element, and an A / D converter that amplifies and analog-to-digital (A / D) converts the electrical signal output from the imaging element. The first imaging device 118a captures an area of ​​the surface of the conveyed medium facing the line sensor at regular intervals, sequentially generating and outputting line images. That is, the line image has one pixel in the vertical direction (sub-scanning direction) and multiple pixels in the horizontal direction (main scanning direction). The first imaging device 118a is an example of a width detection unit, and is used to detect the width of the medium conveyed by the conveyance unit in a width direction A2 perpendicular to the conveyance direction.

[0029] Similarly, the second imaging device 118b is disposed downstream of the first conveyance roller 116 and the second conveyance roller 117 in the medium conveyance direction A1. The second imaging device 118b has a CIS line sensor with a 1x magnification optical system having CMOS image sensors linearly arranged in the main scanning direction. The line sensor is an example of an image sensor that captures an image of a medium. The second imaging device 118b also has a light source that irradiates light onto the conveyed medium, a lens that forms an image on the image sensor, and an A / D converter that amplifies and analog-to-digital (A / D) converts the electrical signal output from the image sensor. The second imaging device 118b captures an image of an area facing the line sensor on the back side of the conveyed medium at regular intervals, sequentially generating and outputting line images. The second imaging device 118b is an example of a width detection unit and is used to detect the width of the medium conveyed by the conveyance unit in the width direction A2, which is perpendicular to the conveyance direction.

[0030] Note that the medium conveying device 100 may have only one of the first and second imaging devices 118a and 118b, and may read only one side of the medium. Also, instead of a CIS line sensor with an equal-magnification optical system and a CMOS imaging element, a CIS line sensor with an equal-magnification optical system and a CCD (Charge Coupled Device) imaging element may be used. Also, a reduction optical system type line sensor with a CMOS or CCD imaging element may be used.

[0031] The media placed on the mounting table 103 is transported between the lower guide 107a and the upper guide 107b in the media transport direction A1 by the rotation of the feed roller 112 in the direction of arrow A4 in FIG. 2. The brake roller 113 rotates in the direction of arrow A5 when transporting the media. When multiple media are placed on the mounting table 103, the feed roller 112 and the brake roller 113 function to separate only the media placed on the mounting table 103 that are in contact with the feed roller 112. This operates to restrict the transport of media other than the separated media (preventing double feeding). The feed roller 112 and the brake roller 113 are an example of a feeding unit that separates and feeds the media placed on the mounting table 103.

[0032] The medium is guided by lower guide 107a and upper guide 107b and fed between first conveyor roller 116 and second conveyor roller 117. The medium is fed between first image capture device 118a and second image capture device 118b as first conveyor roller 116 and second conveyor roller 117 rotate in the directions of arrows A6 and A7, respectively. After being scanned by image capture device 118, the medium is ejected onto ejection tray 104 as third conveyor roller 119 and fourth conveyor roller 120 rotate in the directions of arrows A8 and A9, respectively.

[0033] FIG. 3 is a schematic diagram for explaining the arrangement of the ultrasonic sensors 115 and the like.

[0034] 3 is a schematic diagram of the lower guide 107a viewed from above with the upper housing 102 open. In the example shown in FIG. 3, four ultrasonic sensors 115 are arranged side by side at intervals in the width direction A2. In particular, the ultrasonic sensors 115 are arranged at equal intervals in the width direction A2. Of the four ultrasonic sensors 115, the outermost ultrasonic sensors 115 are arranged at both ends of the lower guide 107a in the width direction A2, and are thereby able to detect overlapping of media at both ends in the width direction A2. Note that the number of ultrasonic sensors 115 is not limited to four, and may be three or less or five or more.

[0035] FIG. 4 is a block diagram showing a schematic configuration of the medium conveying device 100. As shown in FIG.

[0036] In addition to the above-described components, the medium conveying device 100 further includes a motor 131, an interface device 132, a storage device 140, a processing circuit 150, and the like.

[0037] The motor 131 includes one or more motors, and rotates the feed roller 112, the brake roller 113, and the first to fourth transport rollers 116, 117, 119, and 120 in response to a control signal from the processing circuit 150 to transport the medium.

[0038] The interface device 132 has an interface circuit conforming to a serial bus such as USB, and is electrically connected to an information processing device (not shown) to transmit and receive a medium image generated based on the line image and various information. Alternatively, the interface device 132 may be replaced by a communication unit having an antenna for transmitting and receiving wireless signals and a wireless communication interface device for transmitting and receiving signals via a wireless communication line in accordance with a predetermined communication protocol. The predetermined communication protocol is, for example, a wireless LAN (Local Area Network).

[0039] The storage device 140 includes a memory device such as a RAM (Random Access Memory) or a ROM (Read Only Memory), a fixed disk device such as a hard disk, or a portable storage device such as a flexible disk or optical disk. The storage device 140 also stores computer programs, databases, tables, and the like used for various processes of the medium conveying device 100. The computer programs may be installed into the storage device 140 from a computer-readable, non-transitory portable recording medium using a known setup program or the like. The portable recording medium is, for example, a CD-ROM (Compact Disc Read Only Memory), a DVD-ROM (Digital Versatile Disc Read Only Memory), or the like.

[0040] The storage device 140 stores data such as the dimensions and positions of the ultrasonic sensors 115 on the medium transport path, and the position of the image capture device 118.

[0041] The processing circuit 150 operates based on a program stored in advance in the storage device 140. The processing circuit 150 is, for example, a CPU (Central Processing Unit). The processing circuit 150 may be a DSP (Digital Signal Processor), an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or the like.

[0042] The processing circuit 150 is connected to the operation device 105, display device 106, contact sensor 111, medium sensor 114, ultrasonic sensor 115, imaging device 118, motor 131, interface device 132, storage device 140, etc., and controls each of these components. The processing circuit 150 performs drive control of the motor 131, image capture control of the imaging device 118, etc., generates a medium image, and transmits it to the information processing device via the interface device 132. The processing circuit 150 also determines whether or not to perform abnormality processing due to double feeding, based on the width of the medium calculated based on the detection result of the imaging device 118 and the detection result of the ultrasonic sensor 115.

[0043] FIG. 5 is a diagram showing a schematic configuration of the storage device 140 and the processing circuit 150. As shown in FIG.

[0044] 5, the storage device 140 stores a control program 141, an image generation program 142, etc. Each of these programs is a functional module implemented by software running on a processor. The processing circuitry 150 reads each program stored in the storage device 140 and operates in accordance with the read program. As a result, the processing circuitry 150 functions as a control unit 151 and an image generation unit 152.

[0045] FIG. 6 is a flowchart showing an example of the operation of the medium reading process of the medium conveying device 100.

[0046] An example of the operation of the medium reading process of the medium conveying device 100 will be described below with reference to the flowchart shown in FIG. 6. The operation flow described below is executed mainly by the processing circuit 150 in cooperation with each element of the medium conveying device 100 based on a program previously stored in the storage device 140. The operation flow shown in FIG. 6 is executed periodically. The medium conveying device 100 has two feeding modes for feeding media: a separation mode in which multiple media are separated and fed, and a non-separation mode in which the media are fed without being separated. The operation flow shown in FIG. 6 is executed when the feeding mode is set to the separation mode.

[0047] First, the control unit 151 waits until a user inputs an instruction to read a medium using the operation device 105 and an operation signal instructing to read a medium is received from the operation device 105 (step S101).

[0048] Next, the control unit 151 acquires a first medium signal from the contact sensor 111, and determines whether or not a medium is placed on the placement table 103 based on the acquired first medium signal (step S102).

[0049] If no medium is placed on the placement table 103, the control unit 151 returns the process to step S101 and waits until a new operation signal is received from the operation device 105.

[0050] On the other hand, when a medium is placed on the placement table 103, the control unit 151 drives the motor 131 to rotate the feed roller 112, the brake roller 113, and the first to fourth transport rollers 116, 117, 119, and 120 to transport the medium (step S103). In the separation mode, the control unit 151 drives the motor 131 to rotate the feed roller 112 and the first to fourth transport rollers 116, 117, 119, and 120 in the directions of arrows A4, A6, A7, A8, and A9 (the medium feed direction or medium transport direction), respectively. The control unit 151 also drives the motor 131 to rotate the brake roller 113 in the direction of arrow A5 (the direction opposite to the medium feed direction).

[0051] Next, the control unit 151 detects the width of the medium (step S104). The control unit 151 acquires a line image from the imaging device 118, and identifies the positions of the edges of the medium based on the acquired line image.

[0052] The control unit 151 extracts edge pixels from the line image. The control unit 151 calculates the absolute value of the difference in gradation values ​​between the pixels horizontally adjacent to each pixel in the line image (hereinafter referred to as the adjacent difference value), and if the adjacent difference value exceeds a threshold value Th1, extracts the pixel as an edge pixel. The gradation value is a luminance value or an RGB value. This threshold value Th1 can be set to, for example, a difference in luminance values ​​(e.g., 20) that allows a person to visually distinguish the difference in luminance on the image. The control unit 151 detects the edge pixel located on the leftmost side in the line image as the left-end edge pixel, and detects the edge pixel located on the rightmost side as the right-end edge pixel.

[0053] The control unit 151 may extract edge pixels by calculating the average value of the gradation values ​​of multiple pixels that include each pixel and are adjacent to the pixel on the side where the pixel is located, and then extracting edge pixels based on the absolute value of the difference between the two average luminance values. The control unit 151 may also calculate the absolute value of the difference between the gradation values ​​of two pixels that are a predetermined distance away from each pixel in the line image as an adjacent difference value. The control unit 151 may also detect edge pixels by comparing the gradation value of each pixel in the line image with a threshold value. For example, if the gradation value of a specific pixel is less than the threshold value and the gradation value of a pixel adjacent to the specific pixel or a pixel a predetermined distance away from the specific pixel is greater than or equal to the threshold value, the control unit 151 detects the specific pixel as an edge pixel.

[0054] The control unit 151 refers to the placement position of the imaging device 118 stored in the storage device 140, and identifies the positions on the medium transport path that correspond to the positions of the left-end edge pixel and the right-end edge pixel extracted in the line image as the positions of the edges of the transported medium. The control unit 151 detects the distance between the positions of the left-end edge pixel and the right-end edge pixel as the width of the medium.

[0055] Fig. 7(A) shows an example of a medium image, and Fig. 7(B) is an example of a graph showing the luminance value of each pixel in a specific line image within the medium image.

[0056] In Figure 7(B), the horizontal axis indicates the position of a pixel in the line image, and the vertical axis indicates the brightness value of each pixel. As shown in Figures 7(A) and 7(B), the brightness value changes at the boundary between the medium and the background in the line image. In the example shown in Figures 7(A) and 7(B), the pixels corresponding to the left edge position M1 and the right edge position M2 of the medium are extracted as the left edge pixel and the right edge pixel.

[0057] Next, the control unit 151 determines whether or not it has been determined in the overlap determination process that an overlap of media has occurred (step S105). In the overlap determination process, the control unit 151 determines whether or not an overlap of media has occurred for each ultrasonic sensor 115. Details of the overlap determination process will be described later. If it has been determined in the overlap determination process that an overlap of media has not occurred (step S105-No), the control unit 151 proceeds to step S116.

[0058] On the other hand, if it is determined that an overlap of the media has occurred in the overlap determination process (step S105-Yes), the control unit 151 calculates the overlap detection width (step S106). The overlap detection width is the width where the media are estimated to overlap in the direction A2 perpendicular to the medium transport direction.

[0059] When the ultrasonic sensor 115 that determines that a medium overlap has occurred in the overlap determination process, i.e., when the number of ultrasonic sensors 115 that detected a medium overlap is one, the control unit 151 calculates the dimension of the ultrasonic receiver 115b as the overlap detection width. On the other hand, when the number of ultrasonic sensors 115 that detected a medium overlap is multiple, the control unit 151 identifies the ultrasonic sensor 115 that is located on the outermost side in the width direction A2 (closest to each side wall of the medium conveyance path) among the ultrasonic sensors 115 that detected the medium overlap. The control unit 151 reads the placement positions of the identified ultrasonic sensors 115 from the storage device 140 and calculates the distance between the read placement positions as the overlap detection width. In this way, the control unit 151 calculates the overlap detection width based on the detection results of the ultrasonic sensors 115. In particular, the control unit 151 calculates the overlap detection width based on the detection results and placement positions of the multiple ultrasonic sensors 115. This allows the control unit 151 to calculate the overlap detection width with high accuracy.

[0060] 8(A) to 8(D) are schematic diagrams for explaining the overlap detection width.

[0061] 8A shows an example in which the number of ultrasonic sensors that detects an overlap of media is one (the leftmost ultrasonic sensor 115). In this case, the dimension of the ultrasonic receiver 115b is calculated as the overlap detection width W2.

[0062] 8(B) shows an example in which two ultrasonic sensors detect an overlap of media (the leftmost ultrasonic sensor 115 and the second ultrasonic sensor 115 from the left). In this case, the distance between the leftmost ultrasonic sensor 115 and the second ultrasonic sensor 115 from the left is calculated as the overlap detection width W2. This detection width W2 may include the dimensions of the ultrasonic receivers 115b on both ends.

[0063] 8(C) shows an example in which three ultrasonic sensors detect an overlap of media (the leftmost ultrasonic sensor 115, the second ultrasonic sensor 115 from the left, and the third ultrasonic sensor 115 from the left). In this case, the distance between the leftmost ultrasonic sensor 115 and the third ultrasonic sensor 115 from the left is calculated as the overlap detection width W2. This detection width W2 may include the dimensions of the ultrasonic receivers 115b on both ends.

[0064] 8(D) shows an example in which the number of ultrasonic sensors that detected the overlap of the media is four. In this case, the distance between the leftmost ultrasonic sensor 115 and the rightmost ultrasonic sensor 115 is calculated as the overlap detection width W2. This detection width W2 may include the dimensions of the ultrasonic receivers 115b on both ends.

[0065] Next, the control unit 151 determines whether the width of the medium detected in step S104 is equal to the overlap detection width calculated in step S106 (step S107). The term "the width of the medium and the overlap detection width are equal" not only means that the width of the medium and the overlap detection width are the same, but also means that the difference between the width of the medium and the overlap detection width is equal to or less than a predetermined difference. The predetermined difference is the sum of the size of the transmission area through which ultrasonic waves pass through the medium in the ultrasonic sensors 115 and the detection accuracy of the width of the medium, i.e., the distance between two adjacent ultrasonic sensors 115. The control unit 151 determines whether the width of the medium and the overlap detection width are equal by taking into account the detection accuracy of the width of the medium and / or the detection accuracy of the overlap detection width. For example, the control unit 151 determines that the width of the medium and the overlap detection width are equal if the following formula is satisfied:

[0066] W2-α≦W1≦W2+α (1)

[0067] Here, W1 is the width of the medium, and W2 is the overlap detection width. α is a positive number that is set appropriately based on the detection accuracy of the medium width and the overlap detection width. For example, α is set to the sum of the size of the transmission area through which ultrasonic waves pass through the medium in the ultrasonic sensor 115 and the distance between two adjacent ultrasonic sensors 115.

[0068] If the width of the medium and the overlap detection width are equal (step S107-Yes), the control unit 151 determines that a multi-feed of media has occurred (step S108).

[0069] Next, as an abnormality process due to the double feed, the control unit 151 stops the motor 131 to stop the feeding and transport of the media (step S109). When a double feed of media has occurred, the control unit 151 can prevent damage to the media by stopping the feeding and transport of the media. Furthermore, as an abnormality process, the control unit 151 displays a message that a double feed has occurred on the display device 106 or transmits the message to the information processing device via the interface device 132, and notifies the user of a warning.

[0070] In this way, the control unit 151 determines whether or not to perform abnormality processing due to double feeding based on the width of the medium determined based on the detection result of the imaging device 118 and the detection result of the ultrasonic sensor 115. In particular, the control unit 151 performs abnormality processing when the width of the medium and the overlap detection width are equal.

[0071] Next, the control unit 151 drives the motor 131 to rotate the feed roller 112 and the first to fourth transport rollers 116, 117, 119, and 120 in the directions opposite to the arrows A4, A6, A7, A8, and A9 (medium feed direction or medium transport direction), respectively. The control unit 151 also drives the motor 131 to rotate the brake roller 113 in the direction of the arrow A5 (the direction opposite to the medium feed direction). As a result, the control unit 151 reverses the medium and returns it to the mounting table 103 (step S110).

[0072] Next, the control unit 151 changes the feeding mode from the separation mode to the non-separation mode (step S111). In the non-separation mode, the control unit 151 rotates the feeding roller 112 and the first to fourth conveying rollers 116, 117, 119, and 120 in the directions of arrows A4, A6, A7, A8, and A9 (the medium feeding direction or the medium conveying direction), respectively. In the non-separation mode, the control unit 151 cuts off the driving force from the motor 131 to the brake roller 113, thereby turning off the separation function of the medium being fed. Note that the control unit 151 may turn off the separation function of the medium being fed by rotating the brake roller 113 in the medium feeding direction (the opposite direction of arrow A5) or by reducing the separating force of the brake roller 113. Note that in step S111, instead of turning off the separation function, the control unit 151 may control the driving force to the brake roller 113 to reduce or increase the separating force.

[0073] Next, the control unit 151 drives the motor 131 again to rotate the feed roller 112 and the first to fourth transport rollers 116, 117, 119, 120 again in the medium feed direction or medium transport direction, thereby re-feeding and re-transporting the medium (step S112). Next, the control unit 151 moves the process to step S104. At this time, the brake roller 113 is driven by the feed roller 112 or is rotated in the medium feed direction by the motor 131, and does not separate the medium.

[0074] In this way, as an abnormality process, the control unit 151 stops feeding of the medium, returns the medium to the mounting table 103, and controls the feed roller 112 and the brake roller 113 so that the medium is fed again without being separated. This eliminates the need for the user to turn off the medium separation function and feed the medium again, allowing the control unit 151 to improve user convenience. Note that the processes of steps S113 and S115 may be omitted, and the control unit 151 may simply change the feeding mode while stopping the feeding and transport of the medium. In this case, the user does not need to change the feeding mode, allowing the control unit 151 to improve user convenience.

[0075] On the other hand, if the width of the medium and the overlap detection width are not equal (step S107-No), the control unit 151 determines that the width of the medium is larger than the overlap detection width (step S113).

[0076] Next, the control unit 151 calculates the overlap detection length (step S114) based on the detection results of each ultrasonic sensor 115. The overlap detection length is the length by which the medium is estimated to overlap along the medium transport direction A1.

[0077] For each ultrasonic sensor 115 that detected a medium overlap in the overlap determination process, the control unit 151 calculates the period during which the ultrasonic signal output from each ultrasonic sensor 115 continuously showed a value less than the overlap threshold value (described below). The control unit 151 calculates a multiplication value by multiplying the calculated period by the amount of medium feed per unit time by the feed roller 112. The control unit 151 selects the maximum value of the calculated values ​​for each ultrasonic sensor 115 as the overlap detection length. In this way, the control unit 151 determines the overlap detection length based on the detection results of the ultrasonic sensors 115. In particular, the control unit 151 determines the overlap detection length based on the detection results of at least one of the multiple ultrasonic sensors 115. This allows the control unit 151 to determine the overlap detection length with high accuracy.

[0078] Next, the control unit 151 determines whether the overlap detection length is equal to or greater than a length threshold (step S115). The length threshold is set to, for example, a value obtained by adding a margin to the size of a photo, a stamp, or other attachment typically affixed to a resume.

[0079] If the overlap detection length is equal to or greater than the length threshold (step S115-Yes), the control unit 151 determines that a medium transport abnormality has occurred (step S108). Next, the control unit 151 executes abnormality processing due to double feeding (steps S109-S112), as in the case where the medium width and the overlap detection width are equal, and proceeds to step S104.

[0080] On the other hand, if the overlap detection length is smaller than the length threshold (step S115-No), the control unit 151 determines whether the entire medium has passed the imaging position of the imaging device 118 (step S116). The control unit 151 determines whether the trailing edge of the medium has passed the position of the media sensor 114, for example, based on the second medium signal received from the media sensor 114. The control unit 151 periodically acquires the second medium signal from the media sensor 114, and determines that the trailing edge of the medium has passed the position of the media sensor 114 when the signal value of the second medium signal changes from a value indicating the presence of the medium to a value indicating the absence of the medium. The control unit 151 determines that the trailing edge of the medium has passed the imaging position of the imaging device 118 and that the entire medium has been imaged when a predetermined time has elapsed since the trailing edge of the medium passed the position of the media sensor 114. Note that the control unit 151 may also determine that the entire transported medium has been imaged when a predetermined time has elapsed since the start of feeding the medium. If the entire medium has not yet passed the imaging position, the control unit 151 returns the process to step S104.

[0081] On the other hand, if the entire medium has passed the imaging position, the control unit 151 determines that a multi-feed of media has not occurred (step S117).

[0082] That is, the control unit 151 does not execute abnormality processing due to a multi-feed when the width of the medium is greater than the overlap detection width and the overlap detection length is less than the length threshold. This prevents the control unit 151 from erroneously determining that a multi-feed has occurred and stopping the feeding of the medium when a medium with a sticker attached is being transported. Therefore, the medium transport device 100 can prevent the user from having to reset the medium and re-feed it, improving user convenience. On the other hand, when a small medium is transported overlapping a large medium, the control unit 151 can determine that a multi-feed has occurred and execute appropriate abnormality processing.

[0083] In steps S114 and S115, the control unit 151 may determine whether the signal value of the ultrasonic signal is equal to or greater than a second overlap threshold, instead of or in addition to determining whether the overlap detection length is equal to or greater than the length threshold. The second overlap threshold is set to a value smaller than the overlap threshold. In particular, the second overlap threshold is set to a value between the signal value of the ultrasonic signal when two media are overlapping without being attached and the signal value of the ultrasonic signal when a sticker is attached to the medium. When a sticker is attached to the medium, there is no air gap between the medium and the sticker, so the amount of ultrasonic attenuation is smaller than when two media are overlapping without being attached. When the width of the medium is greater than the overlap detection width and the signal value of the ultrasonic signal is equal to or greater than the second overlap threshold, the control unit 151 determines that media with a sticker attached are being transported and does not perform abnormality processing due to double feeding. This allows the control unit 151 to accurately determine whether a medium with a sticker attached is being transported or whether a small medium is being transported overlapping a large medium.

[0084] Note that the processing of steps S114 to S115 may be omitted, and the control unit 151 may determine that a multifeed of media has not occurred and not execute abnormality processing due to a multifeed when the width of the medium is greater than the overlap detection width. In this case, too, the control unit 151 can prevent the control unit 151 from erroneously determining that a multifeed has occurred and stopping the feeding of the medium when a medium with a sticker attached is transported. The control unit 151 may also receive a setting from the user using the operation device 105 as to whether or not to execute the processing of steps S114 to S115. The user can set the processing of steps S114 to S115 to be omitted when there is a low possibility that media of different sizes will be mixed. This reduces the processing load of the medium reading processing, while preventing the control unit 151 from erroneously determining that a multifeed has occurred and stopping the feeding of the medium when a medium with a sticker attached is transported.

[0085] Next, the image generation unit 152 acquires each line image generated during medium transport from the imaging device 118, synthesizes all the acquired line images to generate a medium image, and transmits it to the information processing device via the interface device 132 (step S118).

[0086] Next, control unit 151 determines whether or not a medium remains on mounting table 103 based on the first medium signal acquired from contact sensor 111 (step S119). If a medium remains on mounting table 103, control unit 151 returns the process to step S104 and repeats the processes of steps S104 to S119.

[0087] On the other hand, if there are no media remaining on the mounting table 103, the control unit 151 stops the motor 131 to stop the transport of the media (step S120), and ends the series of steps.

[0088] It should be noted that, if the processing of steps S110 to S112 is omitted and the control unit 151 stops feeding and transporting the medium, the series of steps may be ended without feeding the medium again.

[0089] FIG. 9 is a flowchart showing an example of the operation of the overlap determination process.

[0090] An example of the operation of the validity determination process of medium conveying device 100 will be described below with reference to the flowchart shown in Fig. 9. The operation flow described below is executed mainly by processing circuit 150 in cooperation with each element of medium conveying device 100 based on a program stored in advance in storage device 140. The operation flow shown in Fig. 9 is executed periodically during medium conveyance.

[0091] First, the control unit 151 acquires an ultrasonic signal from each ultrasonic sensor 115 (step S201).

[0092] Next, the control unit 151 determines whether the signal value of each acquired ultrasonic signal is less than the overlap threshold (step S202). The overlap threshold is set to a value between the signal value of the ultrasonic signal when one sheet of media is being conveyed and the signal value of the ultrasonic signal when media overlap.

[0093] If the signal values ​​of all the ultrasonic signals are equal to or greater than the overlap threshold, the control unit 151 determines that no overlap of the media has occurred (step S203) and ends the series of steps. On the other hand, if the signal value of any of the ultrasonic signals is less than the overlap threshold, the control unit 151 determines that an overlap of the media has occurred (step S204) and ends the series of steps.

[0094] In this way, the multifeed determiner 154 determines whether or not overlapping of media has occurred based on the ultrasonic signal.

[0095] 10A and 10B are schematic diagrams for explaining the technical significance of determining whether or not a multifeed of media has occurred based on the overlap detection width.

[0096] In the example shown in Figure 10(A), media 300A and media 300B having a width W3 approximately equal to the distance W4 between the ultrasonic sensors 115 arranged at both ends are transported, and the rear end of media 300A overlaps with the front end of media 300B.

[0097] In this case, the overlap of media is detected by all ultrasonic sensors 115, and the distance W4 between the ultrasonic sensors 115 arranged at both ends is calculated as the overlap detection width. Because the distance W4 between the ultrasonic sensors 115 arranged at both ends is approximately equal to the width W3 of the medium 300A, it is determined that a double feed of media has occurred.

[0098] After the leading edge of the fed medium is successfully separated by the feed roller 112 and the brake roller 113, the frictional force between the fed medium and the medium in contact with it may become greater than the separating force of the feed roller 112 and the brake roller 113, potentially resulting in double feeding. In this case, as shown in FIG. 10(A), double feeding may not occur at the leading edge of the fed medium 300A, but medium 300B, which is in contact with medium 300A at the trailing edge of medium 300A, may be transported overlapping. Because the overlap length between medium 300A and medium 300B in the medium transport direction A1 may be approximately the same as the adhesive, it is difficult to determine whether a medium with an adhesive attached is being transported or a double feeding of media has occurred based solely on the overlap detection length. Because the medium transport device 100 determines whether a double feeding of media has occurred based on the overlap detection width in the width direction A2, it can accurately determine whether a medium with an adhesive attached is being transported or a double feeding of media has occurred.

[0099] Furthermore, when the width of the medium and the overlap detection width are equal, the medium conveying device 100 determines that a double feed of media has occurred without determining the overlap detection length in the medium conveying direction A1. This allows the medium conveying device 100 to immediately perform abnormality processing when a double feed of media has occurred.

[0100] In the example shown in Figure 10(B), a medium 300C having a width W5 approximately equal to the distance W6 between two adjacent ultrasonic sensors 115 is being transported, and having attached thereto a sticker 300D having a width approximately equal to the distance W6 between two adjacent ultrasonic sensors 115.

[0101] In this case, the overlapping of media is detected only by the two ultrasonic sensors 115 facing the adhesive 300D, and the distance W6 between the two ultrasonic sensors 115 is calculated as the overlap detection width. Because the width W5 of the medium 300C is greater than the calculated distance W6 and the length of the overlapping of the media along the medium conveyance direction A1 is less than the length threshold, it is determined that no multi-feed of media has occurred. In this way, the medium conveying device 100 can appropriately detect the occurrence of a multi-feed of media while suppressing erroneous determination that a multi-feed of media has occurred when media with adhesives attached are conveyed. Furthermore, if the length of the overlapping of the media along the medium conveyance direction A1 is equal to or greater than the length threshold, it is determined that a multi-feed of media has occurred. Therefore, the medium conveying device 100 can appropriately detect the occurrence of a multi-feed of media when media of different sizes are conveyed overlapping each other.

[0102] As described above in detail, when an overlap of media occurs and the overlap detection width matches the width of the media, medium conveying device 100 executes abnormality processing due to double feed. This allows medium conveying device 100 to prevent erroneous determination of double feed and more accurately determine whether double feed of media has occurred.

[0103] In the above-described embodiment, abnormality processing is performed after the position of the edge of the medium is detected. However, abnormality processing may also be performed after the medium image is generated by combining line images captured by the imaging device 118. In this case, the processes of steps S104 to S115 are performed after the medium image is generated in step S118. Furthermore, the determination unit 153 periodically acquires ultrasonic signals and stores the signal values ​​of the ultrasonic signals in the storage device 140 for each position on the medium in the medium conveyance direction A1. When the medium image is generated, the control unit 151 calculates the width of the medium for each horizontal line in the medium image and determines whether or not a medium overlap has occurred. If an overlap has occurred, the control unit 151 calculates the overlap detection width, and if the overlap detection width and the medium width match, determines that a medium double feed has occurred. On the other hand, if the overlap detection width and the medium width do not match, the control unit 151 determines whether or not the overlap detection length is equal to or greater than a length threshold, and if the overlap detection length is equal to or greater than the length threshold, determines that a medium double feed has occurred.

[0104] Furthermore, in the above-described embodiment, an ultrasonic sensor that outputs ultrasonic transmission information was used as the overlap detector. However, a thickness sensor that detects thickness information of the medium may also be used as the overlap detector. The thickness sensor is disposed at the location where each ultrasonic sensor 115 is disposed. The thickness sensor includes a light emitter and a light receiver disposed near the medium transport path, facing each other across the transport path. The light emitter emits light (infrared light or visible light) toward the light receiver. Meanwhile, the light receiver receives the light emitted by the light emitter and generates and outputs a thickness signal, which is an electrical signal corresponding to the intensity of the received light. When a medium is present at the thickness sensor, the light emitted by the light emitter is attenuated by the medium, and the greater the thickness of the medium, the greater the amount of attenuation. For example, the thickness sensor generates a thickness signal such that the signal value increases as the medium becomes thicker.

[0105] The thickness sensor may be a reflective light sensor, a pressure sensor, or a mechanical sensor. The reflective light sensor includes a pair of a light emitter and a light receiver provided on one side of the medium transport path and a pair of a light emitter and a light receiver provided on the other side. The reflective light sensor detects the distance between each pair and each side of the medium based on the time between one pair irradiating one side of the medium with light and receiving the reflected light, and the time between the other pair irradiating the other side of the medium with light and receiving the reflected light. The reflective light sensor subtracts each detected distance from the distance between the two pairs and generates a thickness signal indicating the subtracted value as thickness information. The pressure sensor detects pressure, which changes depending on the thickness of the medium, and generates a thickness signal indicating the detected pressure as thickness information. The mechanical sensor detects the amount of movement of a roller in contact with the medium and generates a thickness signal indicating the detected amount of movement as thickness information.

[0106] When a thickness sensor is used as the overlap detection unit, in the overlap determination process, the control unit 151 acquires a thickness signal from the thickness sensor instead of an ultrasonic signal, and determines whether an overlap of media has occurred based on whether the signal value of the acquired thickness signal is equal to or greater than the overlap threshold. Also, in step S106 of FIG. 6, the control unit 151 calculates the overlap detection width based on the detection result of the thickness sensor that detected the overlap. Furthermore, in step S114, the control unit 151 calculates the overlap detection length based on the period during which the thickness signal continuously indicates a value equal to or greater than the overlap threshold.

[0107] Furthermore, in the above-described embodiment, the feed roller 112 was positioned below the brake roller 113 to feed the media placed on the mounting table 103 in order from the bottom up, but the feed roller may also be positioned above the brake roller so that the media placed on the mounting table is fed in order from the top up.

[0108] In the above-described embodiment, an imaging device is used as the width detector, but the width detector is not limited to this.

[0109] FIG. 11 is a schematic diagram for explaining another means for detecting the width of the medium.

[0110] 11, the width detection unit includes a distance measurement sensor 108 for detecting the positions of first side guide 109a and second side guide 109b that regulate the widthwise position of the medium, and control unit 151 identifies the position of the edge of the medium based on the detection result of distance measurement sensor 108. While the following describes detecting the position of second side guide 109b using distance measurement sensor 108, this description also applies appropriately to detecting the position of first side guide 109a using distance measurement sensor 108.

[0111] The distance measuring sensor 108 is disposed in the medium conveying direction A1, i.e., at a predetermined position on the edge of the conveying path in the width direction A2, so as to overlap with the second side guide 109b. The distance measuring sensor 108 measures the distance from the predetermined position to the second side guide 109b. The distance measuring sensor 108 measures the distance to an object located opposite the second side guide 109b based on the time difference between emitting infrared light and receiving the reflected infrared light. The distance measuring sensor 108 includes a light emitter 108a and a light receiver 108b. The light emitter 108a emits light (infrared light) toward the center in the width direction A2, i.e., toward the second side guide 109b. The light receiver 108b receives the light emitted by the light emitter 108a and reflected by the second side guide 109b. The light receiver 108b generates and outputs a detection signal, which is an electrical signal corresponding to the time between when the light emitter 108a emits light and when the light receiver 108b receives the light. That is, the detection signal is a signal corresponding to the distance from a predetermined position where distance sensor 108 is disposed to second side guide 109b. Control unit 151 determines the distance between distance sensor 108 and second side guide 109b based on the position where distance sensor 108 is disposed and the detection signal. Control unit 151 then identifies the position of the edge of the medium on the second side guide 109b side based on the position where distance sensor 108 is disposed, the distance between distance sensor 108 and second side guide 109b, and the thickness of second side guide 109b. Similarly, distance sensor 108 identifies the position of the edge of the medium on the first side guide 109a side.

[0112] The control unit 151 determines the width of the medium based on the position of the edge of the medium on the first side guide 109a side and the position of the edge of the medium on the second side guide 109b side.

[0113] Note that distance measuring sensor 108 may include a transmitter that emits ultrasonic waves and a receiver that receives ultrasonic waves instead of light emitter 108a and light receiver 108b, and measure the distance to second side guide 109b from the time difference between emitting ultrasonic waves and receiving the reflected ultrasonic waves. In this case, distance measuring sensor 108 generates, as a detection signal, an electrical signal corresponding to the time between the transmitter emitting ultrasonic waves and the receiver receiving the ultrasonic waves. Alternatively, distance measuring sensor 108 may include a transmitter that emits audible sounds and a receiver that receives audible sounds, and measure the distance to second side guide 109b from the time difference between emitting audible sounds and receiving the reflected audible sounds. In this case, distance measuring sensor 108 generates, as a detection signal, an electrical signal corresponding to the time between the transmitter emitting audible sounds and the receiver receiving the audible sounds.

[0114] Alternatively, a conductor such as metal may be attached to the second side guide 109b, and an inductive proximity sensor including a coil may be used as the distance measuring sensor 108, which detects magnetic loss due to eddy currents generated on the surface of the conductor. In this case, the distance measuring sensor 108 generates an electrical signal corresponding to the magnitude of impedance in the coil as the detection signal. Alternatively, a metal or dielectric may be attached to the second side guide 109b, and a capacitive proximity sensor may be used as the distance measuring sensor 108, which detects changes in capacitance between the second side guide 109b and the distance measuring sensor 108. In this case, the distance measuring sensor 108 generates an electrical signal corresponding to the magnitude of capacitance between the second side guide 109b and the distance measuring sensor 108 as the detection signal.

[0115] Alternatively, a magnet may be attached to the second side guide 109b, and a magnetic sensor may be used as the distance measuring sensor 108 to detect the magnitude of the magnetic field between the second side guide 109b and the distance measuring sensor 108. In this case, the distance measuring sensor 108 generates an electric signal corresponding to the magnitude of the magnetic field between the second side guide 109b and the distance measuring sensor 108 as a detection signal.

[0116] Alternatively, a sensor including an optical rotary encoder and detecting the amount of movement of second side guide 109b from its initial position (predetermined position) may be used as distance sensor 108. The rotary encoder has a disk with multiple slits formed therein and arranged to rotate in accordance with the movement of second side guide 109b, and a light emitter and a light receiver arranged opposite each other across the disk. In this case, distance sensor 108 generates an electrical signal as a detection signal corresponding to the number of times the state changes between a state where there are slits between the light emitter and the light receiver and a state where there are no slits and the light is blocked by the disk.

[0117] Alternatively, a sensor including an optical linear encoder and detecting the amount of movement of second side guide 109b from its initial position (predetermined position) may be used as distance measuring sensor 108. The optical linear encoder has a glass scale on which a grating is formed, and a light emitter and a light receiver that face each other across the glass scale and move in accordance with the movement of second side guide 109b. In this case, distance measuring sensor 108 generates an electrical signal as a detection signal corresponding to the number of times the light intensity of the light receiver changes.

[0118] Alternatively, a sensor including a magnetic linear encoder and detecting the amount of movement of second side guide 109b from its initial position (predetermined position) may be used as distance measuring sensor 108. The magnetic linear encoder has a magnetic scale on which a predetermined magnetic pattern is formed, and a magnetic detection head that faces the magnetic scale and moves in accordance with the movement of second side guide 109b. In this case, distance measuring sensor 108 generates an electric signal as a detection signal corresponding to the number of magnetic changes detected by the magnetic detection head.

[0119] Alternatively, a sensor including a sliding resistor and detecting the voltage generated by the sliding resistor may be used as distance measuring sensor 108. The sliding resistor has a resistor that extends in width direction A2 and has a constant voltage applied from terminals at both ends, and a contact (slider) that is disposed so as to move in accordance with the movement of second side guide 109b while abutting against the resistor. In this case, second side guide 109b generates an electric signal as a detection signal corresponding to the magnitude of the voltage applied from one end of the resistor to the slider.

[0120] FIG. 12 is a schematic diagram for explaining yet another means for detecting the width of the medium.

[0121] In the example shown in FIG. 12, the width detection unit includes a plurality of medium sensors 214, and the control unit 151 determines the width of the medium based on the detection results of the plurality of medium sensors 214.

[0122] Each media sensor 214 has a configuration similar to that of the media sensor 114. The media sensors 214 are arranged side by side at intervals in the width direction A2. In particular, each media sensor 214 is arranged so as to overlap with each ultrasonic sensor 115 in the width direction A2, that is, so as to overlap with each ultrasonic sensor 115 when viewed from the medium transport direction A1. The control unit 151 calculates the width of the medium as the distance between the media sensors 214 that have detected the medium and that are arranged on the outermost sides in the width direction A2 (closest to each side wall of the medium transport path).

[0123] Furthermore, the medium conveying device 100 may calculate the width of the medium by arranging multiple medium sensors 114 in a line in the width direction perpendicular to the medium conveyance direction.

[0124] The control unit 151 may calculate the width of the medium based on the ultrasonic signals from the ultrasonic sensors 115. In this case, the control unit 151 determines that a medium is present at a position opposite an ultrasonic sensor 115 whose signal value is less than the medium threshold. The medium threshold is set to a value between the signal value of the ultrasonic signal when no medium is present and the signal value of the ultrasonic signal when a single medium is being transported. The control unit 151 calculates the width of the medium as the distance between the ultrasonic sensors 115 that detected the medium and are located on the outermost sides in the width direction A2 (closest to each sidewall of the medium transport path).

[0125] 13 is a diagram showing a schematic configuration of a processing circuit 250 in a medium conveying device according to another embodiment. The processing circuit 250 is used in place of the processing circuit 150 of the medium conveying device 100, and performs control processing including medium reading processing and various calculations and determinations in place of the processing circuit 150. The processing circuit 250 includes a control circuit 251, an image generation circuit 252, and the like. Note that each of these components may be configured as an independent integrated circuit, microprocessor, firmware, or the like.

[0126] The control circuit 251 is an example of a control unit, and has the same functions as the control unit 151. The control circuit 251 receives an operation signal from the operation device 105, a first medium signal from the contact sensor 111, and a second medium signal from the medium sensor 114, and outputs a control signal to the motor 131 so as to control the feeding and transport of the medium in accordance with each of the received signals. The control circuit 251 also receives an ultrasonic signal from the ultrasonic sensor 115, reads out a line image from the storage device 140, and performs abnormal processing due to double feeding based on the medium width determined based on the line image and the ultrasonic signal.

[0127] The image generation circuit 252 is an example of an image generation unit, and has the same function as the image generation unit 152. The image generation circuit 252 receives a line image from the imaging device 118 and stores it in the storage device 140, and also generates a medium image and transmits it to the information processing device via the interface device 132.

[0128] As described above in detail, even when the processing circuit 250 is used, the medium conveying device is able to more accurately determine whether or not a multifeed of media has occurred. [Explanation of symbols]

[0129] 100 medium conveying device, 103 placing table, 111 contact sensor, 112 feeding roller, 113 brake roller, 114 medium sensor, 115 ultrasonic sensor, 116 first conveying roller, 117 second conveying roller, 118 imaging device, 151 control unit, 152 image generating unit, 153 determination unit

Claims

1. a transport unit that transports the medium; a width detection unit for detecting a width of the medium conveyed by the conveyance unit in a direction perpendicular to the conveyance direction; an overlap detection sensor that detects a detection value corresponding to an overlap of the media conveyed by the conveyance unit; a control unit that executes abnormality processing due to double feeding based on the detection result of the width detection unit and the detection result of the overlap detection sensor, the control unit executes the abnormality processing when the width of the medium is larger than the overlap width in a direction perpendicular to the medium transport direction and the overlap length in the medium transport direction is longer than a predetermined length, and does not execute the abnormality processing when the width of the medium is larger than the overlap width and the overlap length is shorter than the predetermined length. A medium transport device characterized by:

2. a transport unit that transports the medium; a width detection unit for detecting a width of the medium conveyed by the conveyance unit in a direction perpendicular to the conveyance direction; an overlap detection sensor that detects a detection value corresponding to an overlap of the media conveyed by the conveyance unit; a control unit that executes abnormality processing due to double feeding based on the detection result of the width detection unit and the detection result of the overlap detection sensor, the control unit executes the abnormality processing when the width of the medium is larger than the overlap width in a direction perpendicular to the medium transport direction and the detection value indicates that two media are overlapping without being pasted, and does not execute the abnormality processing when the width of the medium is larger than the overlap width and the detection value indicates that a sticker is pasted on the medium. A medium transport device characterized by:

3. the overlap detection sensor includes a plurality of detection sensors, The medium transport device according to claim 1 , wherein the control unit determines the overlap width based on the detection results of the plurality of detection sensors and their arrangement positions.

4. The medium transport device according to claim 1 , wherein the control unit determines the overlap length based on a detection result from the overlap detection sensor.

5. the overlap detection sensor includes a plurality of detection sensors, the control unit calculates the overlap width based on the detection results of the plurality of detection sensors and the arrangement positions; The medium transport device according to claim 4 , wherein the control unit determines the overlap length based on a detection result from at least one of the plurality of detection sensors.

6. 5. The medium transport device according to claim 3, wherein the detection sensor is an ultrasonic sensor that detects the intensity of ultrasonic waves transmitted through the medium.

7. A method for controlling a medium transport device having a transport unit that transports a medium, a width detection unit that detects a width of the medium transported by the transport unit in a direction perpendicular to a transport direction, and an overlap detection sensor that detects a detection value corresponding to an overlap of the medium transported by the transport unit, Executes an abnormality process due to double feeding based on the detection result of the width detection unit and the detection result of the overlap detection sensor, In executing the abnormality processing, if the width of the medium is larger than the overlap width in a direction perpendicular to the medium transport direction and the overlap length in the medium transport direction is longer than a predetermined length, the abnormality processing is executed, and if the width of the medium is larger than the overlap width and the overlap length is shorter than the predetermined length, the abnormality processing is not executed. A method for controlling a medium transport device.

8. A method for controlling a medium transport device having a transport unit that transports a medium, a width detection unit that detects a width of the medium transported by the transport unit in a direction perpendicular to a transport direction, and an overlap detection sensor that detects a detection value corresponding to an overlap of the medium transported by the transport unit, Executes an abnormality process due to double feeding based on the detection result of the width detection unit and the detection result of the overlap detection sensor, In executing the abnormality processing, if the width of the medium is larger than the overlap width in a direction perpendicular to the medium transport direction and the detection value indicates that two media are overlapping without being pasted, the abnormality processing is executed, and if the width of the medium is larger than the overlap width and the detection value indicates that a sticker is pasted on the medium, the abnormality processing is not executed. A method for controlling a medium transport device.

9. A control program for a medium transport device having a transport unit that transports a medium, a width detection unit that detects a width of the medium transported by the transport unit in a direction perpendicular to the transport direction, and an overlap detection sensor that detects a detection value corresponding to an overlap of the medium transported by the transport unit, causing the medium transport device to execute abnormality processing due to double feeding based on the detection result of the width detection unit and the detection result of the overlap detection sensor; In executing the abnormality processing, if the width of the medium is larger than the overlap width in a direction perpendicular to the medium transport direction and the overlap length in the medium transport direction is longer than a predetermined length, the abnormality processing is executed, and if the width of the medium is larger than the overlap width and the overlap length is shorter than the predetermined length, the abnormality processing is not executed. A control program for a medium transport device.

10. A control program for a medium transport device having a transport unit that transports a medium, a width detection unit that detects a width of the medium transported by the transport unit in a direction perpendicular to the transport direction, and an overlap detection sensor that detects a detection value corresponding to an overlap of the medium transported by the transport unit, causing the medium transport device to execute abnormality processing due to double feeding based on the detection result of the width detection unit and the detection result of the overlap detection sensor; In executing the abnormality processing, if the width of the medium is larger than the overlap width in a direction perpendicular to the medium transport direction and the detection value indicates that two media are overlapping without being pasted, the abnormality processing is executed, and if the width of the medium is larger than the overlap width and the detection value indicates that a sticker is pasted on the medium, the abnormality processing is not executed. A control program for a medium transport device.

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