Medium conveyance 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 conveying device, a control method, and a control program, and more particularly to a medium conveying device, a control method, and a control program that determine whether or not a duplicate feed of media has occurred. [Background technology]

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

[0003] For example, a document feeder has been disclosed that moves a multi-feed detection sensor, which detects multi-feeding of documents when documents are transported overlapping each other, back and forth in a direction perpendicular to the document transport direction, and determines whether a document has been multi-feeded 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-feeded 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 is provided with a first sensor that is arranged at one end of a medium transport path and detects the passage and double feeding of the medium, and a second sensor that is arranged at the other end of the transport path and detects the passage and double feeding of the medium (see Patent Document 2). This medium transport device determines whether or not the medium is being double-fed based on the detection results of the first and second sensors. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2007-281777 A [Patent Document 2] JP 2019-193219 A Summary of the Invention [Problem to be solved by the invention]

[0006] It is desirable for a medium conveying device to be able to determine with greater accuracy whether or not a double feed of media has occurred.

[0007] An object of the present invention is to provide a medium conveying device, a control method, and a control program that are capable of determining with greater accuracy whether or not a multifeed of media has occurred. [Means for solving the problem]

[0008] A medium transporting device according to one aspect of the present invention has a transporting unit that transports a medium, a width detection unit for detecting the width of the medium transported by the transporting unit in a direction perpendicular to the transport direction, an overlap detection unit that detects overlap of the medium transported by the transporting unit, and a control unit that 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 width detection unit and the detection result of the overlap detection unit, and the control unit determines the overlap detection width, which is the width at which the medium is presumed to overlap in a direction perpendicular to the transport direction of the medium, based on the detection result of the overlap detection unit, and performs abnormality processing if the width of the medium and the overlap detection width are equal.

[0009] Furthermore, a control method according to one aspect of the present invention is a control method for a medium transporting device having a transporting unit that transports a medium, a width detection unit for detecting the width of the medium transported by the transporting unit in a direction perpendicular to the transport direction, and an overlap detection unit that detects overlap of the medium transported by the transporting unit, in which a determination is made as to 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 width detection unit and the detection result of the overlap detection unit, and in the determination, an overlap detection width, which is the width at which the medium is presumed to overlap in a direction perpendicular to the transport direction of the medium, is determined based on the detection result of the overlap detection unit, and abnormality processing is performed if the width of the medium and the overlap detection width are equal.

[0010] 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 for detecting the width of the medium transported by the transporting unit in a direction perpendicular to the transport direction, and an overlap detection unit that detects overlap of the medium transported by the transporting unit, and causes the medium transporting device to determine whether or not to perform abnormality processing due to double feeding based on the width of the medium obtained based on the detection result of the width detection unit and the detection result of the overlap detection unit, and in the determination, an overlap detection width, which is the width at which the medium is presumed to overlap in a direction perpendicular to the transport direction of the medium, is obtained based on the detection result of the overlap detection unit, and abnormality processing is performed if the width of the medium and the overlap detection width are equal. Effect 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 duplicated medium feed has occurred. [Brief description of the drawings]

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

[0013] Hereinafter, a medium conveying device according to one aspect of the present invention will be described with reference to the drawings. However, it should be noted that the technical scope of the present invention is not limited to the embodiment, but extends to the inventions described 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 a medium, which is an original, and captures an image. The medium is paper, a card, a booklet, or the like. The paper includes thin paper or thick paper, and the booklet includes a passport or a bankbook. The medium also includes a medium to which a label (seal) or a small piece of paper (photograph, clipping, postage stamp, revenue stamp, etc.) is attached. The medium conveying device 100 may be a facsimile, a copier, a multifunction printer (MFP, Multifunction Peripheral), or the like. Note that the medium to be conveyed may not be an original but may be a print target, 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 placement table 103, a discharge 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 engages with the lower housing 101 by a hinge so that it can be opened and closed when the medium is jammed or when the inside of the medium conveying device 100 is cleaned.

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

[0018] The placement table 103 engages with the lower housing 101 so that the medium to be transported can be placed thereon. The placement table 103 has a placement surface 103a on which the medium is placed. A first side guide 109a and a second side guide 109b are provided on the placement 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 of the side guides 109a, 109b is provided so as to be movable in the width direction A2 perpendicular to the medium transport direction of the placement table 103. Each of the side guides 109a, 109b has a predetermined height in the height direction A3 and regulates the width direction of the medium placed on the placement table 103. The first side guide 109a and the second side guide 109b are movably provided so as to be disposed at 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 medium.

[0020] The operation device 105 has an input device such as a button and an interface circuit for acquiring a signal from the input device, accepts an input operation by a user, and outputs an operation signal according to the input operation by the user. The display device 106 has a display including a liquid crystal, an organic EL (Electro-Luminescence), 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 a 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 imaging device 118a, a second imaging 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 an example of a transport unit that transports the medium. Note that the number of each roller is not limited to one, and each roller may be multiple. In the following, the first imaging device 118a and the second imaging device 118b may be collectively referred to as the imaging 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 whether or not a medium is placed on the placement table 103 by contacting and detecting the medium. 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 medium sensor 114 is disposed 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 medium sensor 114 is disposed between the feed roller 112 and the ultrasonic transmitter 115a and the ultrasonic receiver 115b in the medium conveying direction A1. The medium sensor 114 detects whether or not a medium is present at that position. The medium sensor 114 includes a light emitter and a light receiver provided on one side of the medium conveying path, and a reflecting member (not shown) such as a mirror provided at a position facing the light emitter and the light receiver across the conveying path. The light emitter irradiates light toward the conveying path. On the other hand, the light receiver receives the light irradiated by the light emitter and reflected by the reflecting member, and generates and outputs a second medium signal, which is an electrical signal according to the intensity of the received light. When a medium is present at the position of the medium sensor 114, the light irradiated 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 are provided in positions facing 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 of the feed roller 112 and the brake roller 113 in the medium conveying direction A1 and upstream of the first conveying roller 116 and the second conveying roller 117 in the medium conveying direction A1. The ultrasonic transmitter 115a and the ultrasonic receiver 115b are disposed near the medium conveying path and facing each other across the conveying path. The ultrasonic transmitter 115a can output ultrasonic waves. Meanwhile, the ultrasonic receiver 115b receives ultrasonic waves transmitted by the ultrasonic transmitter 115a and passing 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 transmitted through the medium. The ultrasonic sensor 115 is an example of an overlap detection unit, and detects an overlap of the medium transported by the transport unit in a detection area, which is an area on the medium passing over the ultrasonic receiver 115b.

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

[0028] The first imaging device 118a is disposed downstream of the first conveying roller 116 and the second conveying roller 117 in the medium conveying direction A1. The first imaging device 118a has a line sensor using a CIS (Contact Image Sensor) of a life-size optical system type having imaging elements using CMOS (Complementary Metal Oxide Semiconductor) linearly arranged in the main scanning direction. Here, the main scanning direction is a direction perpendicular to the medium conveying direction. The line sensor is an example of an imaging sensor that captures an image of a medium. The first imaging device 118a also has a light source that irradiates light toward the medium being conveyed, 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 image of an area facing the line sensor on the surface of the medium being conveyed at regular intervals, sequentially generates line images, and outputs the line images. That is, the number of pixels in the vertical direction (sub-scanning direction) of the line image is one, and the number of pixels in the horizontal direction (main scanning direction) is multiple. The first imaging device 118a is an example of a width detection section, and is used to detect the width of the medium conveyed by the conveying section in a width direction A2 perpendicular to the conveying direction.

[0029] Similarly, the second imaging device 118b is disposed downstream in the medium conveying direction A1 with respect to the first conveying roller 116 and the second conveying roller 117. The second imaging device 118b has a line sensor using a CIS of a 1:1 optical system type having imaging elements using CMOS arranged in a line in the main scanning direction. The line sensor is an example of an imaging sensor that images a medium. The second imaging device 118b also has a light source that irradiates light toward the medium being conveyed, 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 second imaging device 118b captures an area facing the line sensor on the back side of the medium being conveyed at regular intervals, sequentially generates line images, and outputs them. 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 conveying unit in the width direction A2 perpendicular to the conveying direction.

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

[0031] The medium placed on the mounting table 103 is transported between the lower guide 107a and the upper guide 107b in the medium transport direction A1 by the rotation of the feed roller 112 in the direction of the arrow A4 in FIG. 2. The brake roller 113 rotates in the direction of the arrow A5 when transporting the medium. When multiple media are placed on the mounting table 103, the feed roller 112 and the brake roller 113 work 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 feed section that separates and feeds the media placed on the mounting table 103.

[0032] The medium is fed between the first conveyor roller 116 and the second conveyor roller 117 while being guided by the lower guide 107a and the upper guide 107b. The medium is fed between the first imaging device 118a and the second imaging device 118b as the first conveyor roller 116 and the second conveyor roller 117 rotate in the directions of the arrows A6 and A7, respectively. The medium read by the imaging device 118 is discharged onto the discharge tray 104 as the third conveyor roller 119 and the fourth conveyor roller 120 rotate in the directions of the 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 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 capable of detecting overlapping of the 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 components described above, 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 a line image and various information. Also, instead of the interface device 132, a communication unit having an antenna for transmitting and receiving wireless signals and a wireless communication interface device for transmitting and receiving signals through a wireless communication line according to a predetermined communication protocol may be used. 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 random access memory (RAM) or a read only memory (ROM), a fixed disk device such as a hard disk, or a portable storage device such as a flexible disk or an 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 in 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 compact disc read only memory (CD-ROM), a digital versatile disc read only memory (DVD-ROM), 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 previously stored in the storage device 140. The processing circuit 150 is, for example, a CPU (Central Processing Unit). As the processing circuit 150, 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 may be used.

[0042] The processing circuit 150 is connected to the operation device 105, the display device 106, the contact sensor 111, the medium sensor 114, the ultrasonic sensor 115, the imaging device 118, the motor 131, the interface device 132, the 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 execute abnormality processing due to multiple 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.

[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 that runs on a processor. The processing circuitry 150 reads each program stored in the storage device 140 and operates according to the read program. In this way, 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 flow of the operation 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 flow of the operation shown in FIG. 6 is executed periodically. The medium conveying device 100 has, as a feeding mode for feeding the medium, 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 flow of the operation 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, control unit 151 acquires a first medium signal from contact sensor 111, and determines whether or not a medium is placed on 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 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 (opposite 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 position of the edge 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 adjacent to each pixel in the horizontal direction in the line image (hereinafter referred to as adjacent difference value), and extracts the pixel as an edge pixel if the adjacent difference value exceeds a threshold value Th1. The gradation value is a luminance value or an RGB value. This threshold value Th1 can be set to, for example, a luminance value difference (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 edge pixel, and detects the edge pixel located on the rightmost side as the right edge pixel.

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

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

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

[0057] Next, the control unit 151 determines whether or not it is determined that an overlap of media has occurred in the overlap determination process (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 is determined that an overlap of media has not occurred in the overlap determination process (step S105-No), the control unit 151 transitions the process to step S116.

[0058] On the other hand, if it is determined that the medium overlaps 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 medium is estimated to overlap in the direction A2 perpendicular to the medium transport direction.

[0059] When the number of ultrasonic sensors 115 that have been determined to have a medium overlap in the overlap determination process, i.e., the number of ultrasonic sensors 115 that have detected the 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 have detected the 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 conveying path) among the ultrasonic sensors 115 that have detected the medium overlap. The control unit 151 reads out the arrangement positions of the identified ultrasonic sensors 115 from the storage device 140, and calculates the distance between the read arrangement positions as the overlap detection width. In this way, the control unit 151 determines the overlap detection width based on the detection results of the ultrasonic sensors 115. In particular, the control unit 151 determines the overlap detection width based on the detection results and arrangement positions of the multiple ultrasonic sensors 115. This allows the control unit 151 to determine 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 the number of ultrasonic sensors that detect an overlap of media is two (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 at both ends.

[0063] 8(C) shows an example in which the number of ultrasonic sensors that detect an overlap of media is three (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 at both ends.

[0064] 8(D) shows an example in which the number of ultrasonic sensors that detect 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 at 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" includes not only that the width of the medium and the overlap detection width are the same, but also 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 sensor 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 to each other in consideration of 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 to each other when the width of the medium and the overlap detection width satisfy the following formula:

[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, and is set appropriately based on the detection accuracy of the width of the medium and the detection accuracy of the overlap detection width. For example, α is set to the sum of the size of the transmission area in the ultrasonic sensor 115 through which ultrasonic waves pass through the medium and the interval 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 multifeed 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 transporting of the media (step S109). When a double feed of media occurs, the control unit 151 can prevent the media from being damaged by stopping the feeding and transporting of the media. Furthermore, as an abnormality process, the control unit 151 displays a message indicating 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 execute 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. In particular, the control unit 151 executes 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, 120 in the directions opposite to the arrows A4, A6, A7, A8, 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 placement 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 the arrows A4, A6, A7, A8, and A9 (medium feeding direction or 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 to turn off the separation function of the medium to be fed. The control unit 151 may turn off the separation function of the medium to be fed by rotating the brake roller 113 in the medium feeding direction (opposite direction of the arrow A5) or by reducing the separating force of the brake roller 113. 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 to re-feed and re-transport the medium (step S112). Next, the control unit 151 shifts the process to step S104. At this time, the brake roller 113 is driven by the feed roller 112 or 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, and then controls the feeding roller 112 and the brake roller 113 to return the medium to the mounting table 103 and re-feed the medium without separating it. This eliminates the need for the user to turn off the medium separation function and re-feed the medium, 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 execute only a change in the feeding mode while stopping the feeding and transport of the medium. In that 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 from each ultrasonic sensor 115. The overlap detection length is the length by which the medium is estimated to overlap along the transport direction A1 of the medium.

[0077] The control unit 151 calculates, for each ultrasonic sensor 115 that detected an overlap of media in the overlap determination process, the period during which the ultrasonic signal output from each ultrasonic sensor 115 continuously indicated a value less than an overlap threshold value, which will be described later. The control unit 151 calculates a multiplication value by the calculated period and the amount of media feed per unit time of the feed roller 112. The control unit 151 selects the maximum value of the calculation values ​​calculated 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 result by the ultrasonic sensor 115. In particular, the control unit 151 determines the overlap detection length based on the detection result by 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 a value obtained by adding a margin to the size of a photo or a postage 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 in the same manner as when the width of the medium and the overlap detection width are equal (steps S109 to S112), and transitions the processing 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). For example, the control unit 151 determines whether the rear end of the medium has passed the position of the media sensor 114 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 rear end 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 that the medium is present to a value indicating that the medium is not present. The control unit 151 determines that the rear end 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 rear end of the medium passed the position of the media sensor 114. Note that the control unit 151 may determine that the entire transported medium has been imaged when a predetermined time has elapsed since the feeding of the medium began. 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 double feed of media has not occurred (step S117).

[0082] That is, when the width of the medium is larger than the overlap detection width and the overlap detection length is smaller than the length threshold, the control unit 151 does not execute abnormality processing due to double feeding. This makes it possible for the control unit 151 to suppress the control unit 151 from erroneously determining that a double feeding has occurred and stopping the feeding of the medium when a medium with a sticker attached is conveyed. Therefore, the medium conveying device 100 can suppress the user from having to reset the medium and re-feed it, thereby improving user convenience. On the other hand, when a small medium is conveyed overlapping with a large medium, the control unit 151 can determine that a double feeding has occurred and appropriately execute abnormality processing.

[0083] In addition, in steps S114 to 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 the two media are not attached and overlap, 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 layer between the medium and the sticker, so the attenuation of the ultrasonic wave is smaller than when the two media are not attached and overlap. When the width of the medium is larger 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 a medium to which a sticker is attached is being transported, and does not execute abnormality processing due to multiple feeding. This allows the control unit 151 to accurately determine whether a medium with a sticker affixed thereto is being transported, or whether a small medium is being transported overlapping a large medium.

[0084] The processing of steps S114 to S115 may be omitted, and the control unit 151 may determine that a multi-feed of media has not occurred and not execute abnormality processing due to a multi-feed when the width of the medium is greater than the overlap detection width. In this case, too, the control unit 151 can suppress the control unit 151 from erroneously determining that a multi-feed has occurred and stopping the feeding of the medium when a medium to which a sticker has been 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. When there is a low possibility that media of different sizes will be mixed, the user can set to omit the processing of steps S114 to S115. This allows the control unit 151 to reduce the processing load of the medium reading processing and suppress the control unit 151 from erroneously determining that a multi-feed has occurred and stopping the feeding of the medium when a medium to which a sticker has been 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 mounting table 103, control unit 151 stops 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 processes of steps S110 to S112 are 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 the medium conveying device 100 will be described below with reference to the flowchart shown in Fig. 9. The flow of the operation 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 flow of the operation shown in Fig. 9 is executed periodically during medium conveyance.

[0091] First, the control unit 151 acquires ultrasonic signals 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 an 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 transported and the signal value of the ultrasonic signal when media overlap occurs.

[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 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 media has occurred (step S204) and ends the series of steps.

[0094] In this manner, the double feed 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 FIG. 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 leading end of media 300B.

[0097] In this case, the overlap of media is detected by all of the ultrasonic sensors 115, and the distance W4 between the ultrasonic sensors 115 arranged at both ends is calculated as the overlap detection width. Since 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 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 the fed medium becomes greater than the separation force by the feed roller 112 and the brake roller 113, and double feeding may occur. In this case, as shown in FIG. 10(A), double feeding may not occur at the leading edge of the fed medium 300A, and the medium 300B that contacts the medium 300A at the trailing edge of the medium 300A may be transported overlapping. Since the length of overlap between the medium 300A and the 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 the medium has occurred based only on the overlap detection length. The medium transport device 100 determines whether a double feeding of the medium has occurred based on the overlap detection width in the width direction A2, and therefore can accurately determine whether a medium with an adhesive attached is being transported or a double feeding of the medium 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. Therefore, the medium conveying device 100 can immediately execute abnormality processing when a double feed of media has occurred.

[0100] In the example shown in FIG. 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 an adhesive 300D affixed thereto, the width W5 approximately equal to the distance W6 between two adjacent ultrasonic sensors 115.

[0101] In this case, the overlap of the media is detected only by the two ultrasonic sensors 115 facing the sticker 300D, and the distance W6 between the two ultrasonic sensors 115 is calculated as the overlap detection width. Since the width W5 of the medium 300C is greater than the calculated distance W6 and the length of the overlap of the media along the media conveying direction A1 is smaller than the length threshold, it is determined that no double feed of the media has occurred. In this way, the medium conveying device 100 can appropriately detect the occurrence of double feed of the media while suppressing erroneous determination that a double feed of the media has occurred when a medium to which a sticker has been attached is conveyed. In addition, when the length of the overlap of the media along the media conveying direction A1 is equal to or greater than the length threshold, it is determined that a double feed of the media has occurred. Therefore, the medium conveying device 100 can appropriately detect the occurrence of double feed of the 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, the medium conveying device 100 executes abnormality processing due to double feeding. This makes it possible for the medium conveying device 100 to prevent erroneous determination of double feeding, and to more accurately determine whether or not double feeding of media has occurred.

[0103] In the above-described embodiment, the abnormality process is performed after the detection of the position of the edge of the medium, but the abnormality process may be performed after the generation of the medium image by combining the line images photographed 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. In addition, the determination unit 153 periodically acquires an ultrasonic signal, and stores the signal value of the ultrasonic signal in the storage device 140 for each position in the medium transport direction A1 in the medium. When the medium image is generated, the control unit 151 obtains the width of the medium for each horizontal line in the medium image and determines whether or not overlapping of the medium occurs. If overlapping occurs, the control unit 151 obtains the overlap detection width, and if the overlap detection width and the width of the medium match, determines that double feeding of the medium has occurred. On the other hand, if the overlap detection width and the width of the medium do not match, the control unit 151 determines whether or not the overlap detection length is equal to or greater than the length threshold, and if the overlap detection length is equal to or greater than the length threshold, determines that double feeding of the medium has occurred.

[0104] In the above-described embodiment, an ultrasonic sensor that outputs ultrasonic transmission information is used as the overlap detector, but a thickness sensor that detects thickness information of the medium may be used as the overlap detector. The thickness sensor is disposed at a position where each ultrasonic sensor 115 is disposed. The thickness sensor includes a light emitter and a light receiver disposed near the medium transport path and facing each other across the transport path. The light emitter irradiates light (infrared light or visible light) toward the light receiver. Meanwhile, the light receiver receives the light irradiated by the light emitter, and generates and outputs a thickness signal, which is an electrical signal according to the intensity of the received light. When a medium is present at the position of the thickness sensor, the light irradiated 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 becomes greater as the thickness of the medium increases.

[0105] In addition, a reflected light sensor, a pressure sensor, or a mechanical sensor may be used as the thickness sensor. The reflected 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 reflected light sensor detects the distance between each pair and each side of the medium from the time from when one pair irradiates one side of the medium with light to when it receives the reflected light, and the time from when the other pair irradiates the other side of the medium with light to when it receives the reflected light. The reflected light sensor generates a thickness signal indicating a subtraction value obtained by subtracting each detected distance from the distance between the two pairs as thickness information. The pressure sensor detects pressure that changes according to 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 detector, 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] In addition, 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 sequence 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 sequence from the top up.

[0108] In the above-described embodiment, an imaging device is used as the width detection unit, but the width detection unit 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 specifies the position of the edge of the medium based on the detection result of distance measurement sensor 108. Below, detection of the position of second side guide 109b using distance measurement sensor 108 will be described, but this description also applies appropriately to detection of 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., in a predetermined position on the end side of the conveying path in the width direction A2 so as to overlap with the second side guide 109b, and 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 at the opposite position from 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 side in the width direction A2, i.e., toward the second side guide 109b. On the other hand, the light receiver 108b receives the light irradiated by the light emitter 108a and reflected by the second side guide 109b, and generates and outputs a detection signal, which is an electrical signal corresponding to the time from when the light emitter 108a irradiates light to when the light receiver 108b receives the light. That is, the detection signal is a signal according to the distance from a predetermined position where the distance sensor 108 is disposed to the second side guide 109b. The control unit 151 obtains the distance between the distance sensor 108 and the second side guide 109b based on the position where the distance sensor 108 is disposed and the detection signal. Then, the control unit 151 identifies the position of the edge of the medium on the second side guide 109b side based on the position where the distance sensor 108 is disposed, the distance between the distance sensor 108 and the second side guide 109b, and the thickness of the second side guide 109b. Similarly, the 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] The distance measuring sensor 108 may include a transmitter that emits ultrasonic waves and a receiver that receives ultrasonic waves instead of the light emitter 108a and the light receiver 108b, and may measure the distance to the second side guide 109b from the time difference between when the ultrasonic waves are emitted and when the reflected ultrasonic waves are received. In this case, the distance measuring sensor 108 generates an electric signal as a detection signal according to the time between when the transmitter emits ultrasonic waves and when the receiver receives the ultrasonic waves. Alternatively, the distance measuring sensor 108 may include a transmitter that emits audible sounds and a receiver that receives audible sounds, and may measure the distance to the second side guide 109b from the time difference between when the audible sounds are emitted and when the reflected audible sounds are received. In this case, the distance measuring sensor 108 generates an electric signal as a detection signal according to the time between when the transmitter emits audible sounds and when the receiver receives the audible sounds.

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

[0115] Also, a magnet may be attached to the second side guide 109b, and a magnetic sensor that detects the magnitude of the earth field (magnetic field) between the second side guide 109b and the distance measuring sensor 108 may be used as the distance measuring sensor 108. In this case, the distance measuring sensor 108 generates an electric signal according 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 measuring sensor 108. The rotary encoder has a disk in which many slits are formed and which is arranged to rotate in accordance with the movement of second side guide 109b, and a light emitter and a light receiver which are arranged to face each other across the disk. In this case, distance measuring sensor 108 generates an electric signal as a detection signal according to the number of times that a state in which there is a slit between the light emitter and the light receiver and a state in which there is no slit and they are blocked by the disk.

[0117] Further, 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 lattice scale 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 corresponding to the number of times the amount of light changes in the light receiver as a detection signal.

[0118] Further, a sensor including a magnetic linear encoder and detecting the amount of movement of the second side guide 109b from its initial position (predetermined position) may be used as the 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 the second side guide 109b. In this case, the distance measuring sensor 108 generates an electric signal as a detection signal according to the number of magnetic changes detected by the magnetic detection head.

[0119] Further, a sensor including a sliding resistor and detecting the voltage generated by the sliding resistor may be used as the distance measuring sensor 108. The sliding resistor has a resistor extending in the width direction A2 and having a constant voltage applied from terminals at both ends, and a contact (slider) provided to move in accordance with the movement of the second side guide 109b while abutting against the resistor. In this case, the second side guide 109b generates an electric signal as a detection signal according 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 still another means for detecting the width of the medium.

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

[0122] Each media sensor 214 has a similar configuration to 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 media transport direction A1. The control unit 151 calculates 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 media transport path) as the width of the medium.

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

[0124] The control unit 151 may calculate the width of the medium based on the ultrasonic signal from the ultrasonic sensor 115. In this case, the control unit 151 determines that the medium is present at a position facing the ultrasonic sensor 115 whose signal value of the ultrasonic signal 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 sheet of medium is being transported. The control unit 151 calculates the width of the medium as the distance between the ultrasonic sensors 115 that have detected the medium and that are located on the outermost sides in the width direction A2 (closest to each side wall 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 executes control processing including a medium reading process and various calculations and determinations in place of the processing circuit 150. The processing circuit 250 has a control circuit 251, an image generating circuit 252, and the like. Each of these components may be composed of an independent integrated circuit, microprocessor, firmware, and 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 executes abnormality processing due to double feeding based on the width of the medium 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 placement table, 111 contact sensor, 112 feed 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 unit that detects an overlap of the medium transported by the transport unit; a control unit that determines whether or not to execute abnormality processing due to double feeding based on the width of the medium obtained based on the detection result of the width detection unit and the detection result of the overlap detection unit, The control unit is determining an overlap detection width, which is a width in which the medium is assumed to overlap in a direction perpendicular to the medium transport direction, based on a detection result of the overlap detection unit, and executing the abnormality process when the width of the medium and the overlap detection width are equal; When the width of the medium is larger than the overlap detection width, if an overlap detection length, which is a length that is estimated to be an overlap of the medium in the transport direction of the medium, is equal to or larger than a threshold value, the abnormality processing is executed, and when the overlap detection length is smaller than the threshold value, the abnormality processing is not executed. A medium transport device comprising:

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

3. The medium conveying device according to claim 1 , wherein the control unit determines the overlap detection length based on a detection result by the overlap detection unit.

4. The overlap detection unit includes a plurality of detection sensors, the control unit determines the overlap detection width based on detection results by the plurality of detection sensors and arrangement positions; The medium conveying device according to claim 3 , wherein the control unit determines the overlap detection length based on a detection result by at least one of the plurality of detection sensors.

5. 5. The medium conveying device according to claim 2, wherein the detection sensor is an ultrasonic sensor that detects a transmission intensity of ultrasonic waves transmitted through the medium.

6. 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 unit that detects an overlap of the medium transported by the transport unit, comprising: determining whether or not to execute abnormality processing due to double feeding based on the width of the medium obtained based on the detection result of the width detection unit and the detection result of the overlap detection unit; In the above judgment, determining an overlap detection width, which is a width in which the medium is assumed to overlap in a direction perpendicular to the medium transport direction, based on a detection result of the overlap detection unit, and executing the abnormality process when the width of the medium and the overlap detection width are equal; When the width of the medium is larger than the overlap detection width, if an overlap detection length, which is a length that is estimated to be an overlap of the medium in the transport direction of the medium, is equal to or larger than a threshold value, the abnormality processing is executed, and when the overlap detection length is smaller than the threshold value, the abnormality processing is not executed. A method for controlling a medium transport device comprising:

7. A control program for a medium conveying device having a conveying unit that conveys a medium, a width detection unit that detects a width of the medium conveyed by the conveying unit in a direction perpendicular to a conveying direction, and an overlap detection unit that detects an overlap of the medium conveyed by the conveying unit, causing the medium transport device to determine whether or not to execute abnormality processing due to double feeding based on the width of the medium obtained based on the detection result of the width detection unit and the detection result of the overlap detection unit; In the above judgment, determining an overlap detection width, which is a width in which the medium is assumed to overlap in a direction perpendicular to the medium transport direction, based on a detection result of the overlap detection unit, and executing the abnormality process when the width of the medium and the overlap detection width are equal; When the width of the medium is larger than the overlap detection width, if an overlap detection length, which is a length that is estimated to be an overlap of the medium in the transport direction of the medium, is equal to or larger than a threshold value, the abnormality processing is executed, and when the overlap detection length is smaller than the threshold value, the abnormality processing is not executed. A control program for a medium conveying device.

Images