Medium conveying device, control method, and control program

Abstract

To provide a medium conveyance device, a control method and a control program capable of accurately determining whether or not conveyance abnormality of a medium has occurred.SOLUTION: A medium conveyance device has: a conveyance unit for conveying a medium; an overlap detection sensor; an overlap detection unit for detecting an overlap detection place where overlapping can be regarded as occurring on the medium based on a detection output of the overlap detection sensor concerning a medium to be conveyed by the conveyance unit; a calculation unit for calculating an overlap detection length in which overlap detection places are continuous based on a detection result of the overlap detection unit; a double feed determination unit for determining whether or not the double feed has occurred based on the overlap detection length; and a control unit for executing processing of the abnormality caused by the double feed based on a determination result of the double feed determination unit. When a distance between one overlap detection place and another overlap detected place is within a predetermined distance in calculation of the overlap detection length, the calculation unit determines that the one overlap detection place and the other overlap detection place are continuous.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 multi-feed detection device has been disclosed that calculates an index representing variation from the collection of signal intensities of ultrasonic signals received at multiple points on a sheet being transported, and determines that the sheets are being multi-fed if this index is greater than a predetermined set value (threshold value) (see Patent Document 1).

[0004] Also disclosed is a sheet feeding device having a transmitting means for transmitting a signal toward a sheet conveyed by a conveying means and a receiving means for receiving the signal transmitted through the sheet and outputting an output signal according to the intensity of the received signal (see Patent Document 2). When sheets loaded on a stacking means are of a specific type, this sheet feeding device detects multi-feeding of sheets conveyed by the conveying means according to predetermined values ​​and variation widths of multiple output signals acquired for one sheet. Furthermore, a multi-feed detection device has been disclosed that prevents false detection of documents with attachments by prohibiting multi-feed detection if the length for determining multi-feeding for each document is shorter than a predetermined length (see Patent Document 3). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-147659 [Patent Document 2] Japanese Patent Application Publication No. 2018-95424 [Patent Document 3] Japanese Patent Application Publication No. 07-291485 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; performing overlap detection on the media transported by the transport unit; Based on the overlap detection sensor and the detection output of the overlap detection sensor , overlap are consecutive Overlap length A calculation unit that calculates Overlap length a multifeed determination unit that determines whether or not a multifeed has occurred based on the If it is determined that a double feed has occurred, a control unit that executes abnormality processing, The overlap detection sensor detects multiple feeds at multiple locations within the media. The calculation unit Overlap length In calculating First overlapping point and Second overlapping point The distance between is less than case , the first overlapping point and Second overlapping point is judged to be continuous with The first overlapping portion and the second overlapping portion are portions where the output of the overlap detection sensor indicates an overlap, and the predetermined distance is set to a value greater than the distance between adjacent positions among the multiple positions where overlap detection is performed. .

[0009] A control method according to one aspect of the present invention includes: performing overlap detection on the media transported by the transport unit; Overlap detection sensor ,of A method for controlling a medium transport device comprising: Detection output of overlap detection sensor Based on , overlap are consecutive Overlap length Calculate Overlap length and determining whether a multifeed has occurred based on the If it is determined that a double feed has occurred, performing an abnormality process; The overlap detection sensor detects multiple feeds at multiple positions within the media and measures the overlap length. In calculating First overlapping point and Second overlapping pointThe distance between is less than case , the first overlapping point and Second overlapping point is judged to be continuous with The first overlapping portion and the second overlapping portion are portions where the output of the overlap detection sensor indicates an overlap, and the predetermined distance is set to a value greater than the distance between adjacent positions among the multiple positions where overlap detection is performed. .

[0010] A control program according to one aspect of the present invention includes: a conveying unit that conveys a medium; performing overlap detection on the media transported by the transport unit; Overlap detection sensor ,of A control program for a medium conveying device having: Detection output of overlap detection sensor Based on , overlap are consecutive Overlap length Calculate Overlap length and determining whether a multifeed has occurred based on the If it is determined that a double feed has occurred, causing the medium conveying device to execute abnormality processing; The overlap detection sensor detects multiple feeds at multiple positions within the media and measures the overlap length. In calculating First overlapping point and Second overlapping point The distance between is less than case , the first overlapping point and Second overlapping point is judged to be continuous with The first overlapping portion and the second overlapping portion are portions where the output of the overlap detection sensor indicates an overlap, and the predetermined distance is set to a value greater than the distance between adjacent positions among the multiple positions where overlap detection is performed. . [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 a first 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] 10A shows a graph illustrating the relationship between the signal value of an ultrasonic signal and the position on the medium, and FIG. 10B is a graph for explaining the overlap detection length. [Figure 8] (A) is a schematic diagram for explaining the overlap detection length along the medium transport direction A1, (B) is a schematic diagram for explaining the overlap detection length along the width direction A2, and (C) is a schematic diagram for explaining the distance between each area in the medium that was facing the ultrasonic sensor 115 when the ultrasonic signal was acquired. [Figure 9] 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 a first 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 is paper, a card, a booklet, or the like. Examples of paper include thin paper, PPC (Plain Paper Copier) paper, and thick paper. Examples of booklets include passports and bankbooks. The medium also includes media with labels (stickers) or small pieces of paper (photographs, clippings, postage stamps, revenue stamps, etc.) affixed 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 is engaged 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 108a and a second side guide 108b are provided on the mounting surface 103a.

[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 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, 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 sensor.

[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).

[0029] Similarly, the second imaging device 118b is disposed downstream in the medium conveyance direction A1 relative to the first conveyance roller 116 and the second conveyance roller 117. The second imaging device 118b has a CIS line sensor of a 1:1 optical system type having CMOS image sensors linearly arranged in the main scanning direction. The line sensor is an example of an image sensor that images the 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 the area facing the line sensor on the back side of the conveyed medium at regular intervals, sequentially generating and outputting line images.

[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] FIG. 3 is a schematic diagram of the lower guide 107a viewed from above with the upper housing 102 open. As shown in FIG. 3, a plurality of ultrasonic sensors 115 are arranged along the width direction A2, which is perpendicular to the conveyance direction in which the medium is conveyed. In the example shown in FIG. 3, 20 ultrasonic sensors 115 are arranged at equal intervals between both ends of the width direction A2. This allows the medium conveyance device 100 to detect overlapping of media at multiple positions in the width direction A2. The number of ultrasonic sensors 115 is not limited to 20, and may be 1 to 19 or 21 or more.

[0035] The medium sensor 114 is disposed between the ultrasonic receiver 115b and the feed roller 112 in the medium transport direction A1.

[0036] FIG. 4 is a block diagram showing a schematic configuration of the medium conveying device 100. As shown in FIG.

[0037] 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.

[0038] 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.

[0039] 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).

[0040] 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.

[0041] The storage device 140 stores data such as the positions of the ultrasonic sensors 115 on the medium transport path.

[0042] 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.

[0043] 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 a double feed has occurred based on the ultrasonic signal output by the ultrasonic sensor 115, and performs abnormal processing due to the double feed based on the determination result.

[0044] FIG. 5 is a diagram showing a schematic configuration of the storage device 140 and the processing circuit 150. As shown in FIG.

[0045] 5, the storage device 140 stores a control program 141, an image generation program 142, an overlap detection program 143, a calculation program 144, a multifeed determination program 145, 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, an image generation unit 152, an overlap detection unit 153, a calculation unit 154, and a multifeed determination unit 155.

[0046] FIG. 6 is a flowchart showing an example of the operation of the medium reading process of the medium conveying device 100.

[0047] 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 media are fed without separation. The operation flow shown in FIG. 6 is executed when the feeding mode is set to the separation mode.

[0048] 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).

[0049] 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).

[0050] 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.

[0051] 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).

[0052] Next, overlap detection unit 153 acquires ultrasonic signals from each ultrasonic sensor 115 and stores the signal values ​​of the ultrasonic signals in storage device 140 (step S104). Overlap detection unit 153 acquires ultrasonic signals from each ultrasonic sensor 115 each time motor 131 is driven a predetermined amount. Setting the predetermined amount to a small value enables medium conveyance device 100 to improve the accuracy of detecting double feeds, while setting the predetermined amount to a large value enables the processing load of the medium reading process to be reduced. Overlap detection unit 153 identifies the current position of each ultrasonic sensor 115 on the medium being conveyed, based on the drive amount of motor 131 from the start of medium feeding to the present and the positions of each ultrasonic sensor 115 stored in storage device 140. The position in the medium transport direction A1 is calculated from the transport amount of the motor 131 and the arrangement positions of each ultrasonic sensor 115 in the medium transport direction A1, and the position in the width direction A2 is calculated from the position in the width direction A2 of each ultrasonic sensor 115 that output each ultrasonic signal. The overlap detection unit 153 associates the signal value of the ultrasonic signal with the identified position within the medium and stores it in the storage device 140. Note that the overlap detection unit 153 may also identify the position currently facing each ultrasonic sensor 115 within the medium being transported based on the drive amount by which the motor 131 has been driven since the leading edge of the document passed the medium sensor 114 up to the present time and the arrangement positions of each ultrasonic sensor 115 stored in the storage device 140.

[0053] Next, the control unit 151 determines whether the entire medium has passed the imaging position of the imaging device 118 (step S105). The control unit 151 determines whether the rear end of the medium has passed the position of the medium sensor 114, for example, based on a second medium signal received from the medium sensor 114. The control unit 151 periodically acquires the second medium signal from the medium sensor 114, and determines that the rear end of the medium has passed the position of the medium 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 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 medium 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 feeding of the medium began. If the entire medium has not yet passed the imaging position (step S105—No), the control unit 151 returns to step S104.

[0054] On the other hand, if the entire medium has passed the imaging position (step S105-Yes), the overlap detection unit 153 reads the signal values ​​of each ultrasonic signal from the storage device 140 and detects an overlap detection point on the medium based on the signal values ​​of the read ultrasonic signals (step S106). The overlap detection point is a point where it can be assumed that an overlap has occurred on the medium.

[0055] The overlap detection unit 153 detects overlap detection points for the medium being transported by the transport unit based on the detection output of the ultrasonic sensor 115. The overlap detection unit 153 detects overlap detection points by comparing the transmission intensity detected by the ultrasonic sensor 115 with an overlap threshold. The overlap detection unit 153 detects each position within the medium stored in association with an ultrasonic signal whose signal value is less than the overlap threshold as an overlap detection point. On the other hand, the overlap detection unit 153 determines that no overlap has occurred for each position within the medium stored in association with an ultrasonic signal whose signal value is equal to or greater than the overlap threshold. The overlap threshold is set to a value between the signal value of the ultrasonic signal when a single piece of medium is being transported and the signal value of the ultrasonic signal when an overlapping of media has occurred. This allows the overlap detection unit 153 to accurately identify the position where an overlap has occurred within the medium.

[0056] Furthermore, the overlap detection unit 153 detects overlap detection points based on the ultrasonic signals acquired each time the motor 131 is driven by a predetermined amount. That is, the overlap detection unit 153 detects whether or not an overlap detection point exists at a predetermined cycle. This allows the overlap detection unit 153 to accurately detect multi-feeding of media while suppressing an increase in the processing load of the medium reading process.

[0057] FIG. 7A shows a graph showing the relationship between the signal value of the ultrasonic signal and the position on the medium.

[0058] The vertical axis of Figure 7(A) represents the signal value of the ultrasonic signal, and the horizontal axis represents the position in the transport direction A1 of the medium. The graph shown in Figure 7(A) shows the signal value of the ultrasonic signal output when thin paper is transported in a double-fed state. As shown in Figure 7(A), the intensity of the ultrasonic wave that passes through the thin paper varies due to unevenness in the fibers within the thin paper. Similarly, when regular paper such as PPC paper is transported in a double-fed state, the intensity of the ultrasonic wave that passes through the two sheets of paper also varies due to variations in the distance (air thickness) between the two sheets of paper. As a result, there is a mixture of areas within the medium that are detected as overlap detection points and areas that are not detected as overlap detection points.

[0059] Next, the calculation unit 154 calculates the overlap detection length based on the detection result of the overlap detection unit 153 (step S107).

[0060] The calculation unit 154 calculates the overlap detection length along the medium conveyance direction A1. That is, for each position on the medium facing each ultrasonic sensor 115 in the width direction A2, the calculation unit 154 calculates the length of contiguous overlap detection points in the medium conveyance direction A1 as the overlap detection length. However, even if there is a position between two overlap detection points in the medium conveyance direction A1 where it is determined that no overlap occurs, the calculation unit 154 considers the two overlap detection points to be contiguous if the distance between the two overlap detection points is equal to or less than a reference distance. That is, the calculation unit 154 determines that one overlap detection point and another overlap detection point are contiguous if the distance between the two overlap detection points is within the reference distance. The reference distance is set appropriately based on the thickness or hardness of the medium (thin paper) supported by the medium conveyance device 100. The reference distance is set to the maximum length of a region in which no overlapping of media is detected consecutively in a preliminary experiment in which two sheets of thin paper are transported overlapping each other to detect overlapping detection points, for example.

[0061] FIG. 7B is a graph for explaining the overlap detection length.

[0062] FIG. 7B is a graph similar to that shown in FIG. 7A. In the example shown in FIG. 7B, overlap detection locations are continuous in the first region W1, the second region W2, the third region W3, and the fourth region W4. Between the first region W1 and the second region W2, between the second region W2 and the third region W3, and between the third region W3 and the fourth region W4, there are regions determined to be no overlap (regions having lengths of 20 mm, 6 mm, and 4 mm, respectively). For example, when the reference distance Lth is set to 25 mm, the first region W1, the second region W2, the third region W3, and the fourth region W4 are considered to be continuous, and the length of region W5 (61 mm) from the leading edge of the first region W1 to the trailing edge of the fourth region W4 is calculated as the overlap detection length.

[0063] Next, multifeed determination unit 155 determines whether the overlap detection length calculated by calculation unit 154 is equal to or greater than a length threshold (step S108). The length threshold is set to a value (e.g., 20 mm) between the size of a sticker, such as a photograph or stamp, that is typically affixed to a resume and the size of the smallest size medium supported by medium conveying device 100. This allows multifeed determination unit 155 to appropriately determine whether a medium with a sticker affixed is being conveyed or whether a multifeed of media has occurred.

[0064] If at least one of the overlap detection lengths calculated by the calculation unit 154 is equal to or greater than the length threshold (step S108-Yes), the multifeed determination unit 155 determines that a multifeed of media has occurred (step S109).

[0065] 7A and 7B, the maximum length of overlap detection points that are actually continuous in the medium transport direction A1 is 12 mm in area W3. Therefore, if the length threshold in the medium transport direction A1 is 20 mm, and overlap detection points whose intervals are equal to or less than the reference distance are not considered to be continuous, it is determined that no double feeding of media has occurred.

[0066] Meanwhile, the calculation unit 154 determines that the first region W1, the second region W2, the third region W3, and the fourth region W4 are continuous, and calculates the length of region W5 (61 mm) from the leading edge of the first region W1 to the trailing edge of the fourth region W4 as the overlap detection length. Therefore, the overlap detection length is equal to or greater than the length threshold, and it is determined that a double feed of media has occurred. In this way, the medium conveying device 100 can correctly determine that a double feed of media has occurred, even when a double feed of media occurs in which the intensity of the transmitted ultrasonic waves varies from position to position.

[0067] If it is determined that a multifeed of media has occurred, the control unit 151 stops the motor 131 and stops the feeding and transport of the media as an abnormality process due to the multifeed (step S110). By stopping the feeding and transport of the media when a multifeed of media has occurred, the control unit 151 can prevent damage to the media. Furthermore, as an abnormality process due to the multifeed, the control unit 151 displays a message that a multifeed has occurred on the display device 106 or sends a message to the information processing device via the interface device 132 to notify the user of a warning. In this way, the control unit 151 executes abnormality process due to the multifeed based on the determination result of the multifeed determination unit 155.

[0068] 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 S111).

[0069] Next, the control unit 151 changes the feeding mode from the separation mode to the non-separation mode (step S112). 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 (medium feeding direction or medium conveying direction), respectively. In the non-separation mode, the control unit 151 also turns off the separation function of the medium being fed by cutting off the driving force from the motor 131 to the brake roller 113. Note that the control unit 151 may also 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.

[0070] 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 S113). 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.

[0071] 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 S108 and S110 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.

[0072] On the other hand, if all of the overlap detection lengths calculated by the calculation unit 154 are less than the length threshold (step S108-No), the multifeed determination unit 155 determines that multifeeding of media has not occurred (step S114).

[0073] In this way, the multifeed determination unit 155 determines whether a multifeed of media has occurred based on the overlap detection lengths calculated by the calculation unit 154. In particular, the multifeed determination unit 155 determines whether a multifeed of media has occurred if the maximum value of each overlap detection length calculated by the calculation unit 154 is equal to or greater than the length threshold, and determines whether a multifeed of media has not occurred if the maximum value is less than the length threshold. Note that the multifeed determination unit 155 may also determine whether a multifeed of media has occurred based on a statistical value other than the maximum value of each overlap detection length. The statistical value other than the maximum value may be, for example, an average value, a minimum value, or a median. The multifeed determination unit 155 may determine whether a multifeed of media has occurred if the statistical value of each overlap detection length is equal to or greater than the length threshold, and determine whether a multifeed of media has not occurred if the statistical value is less than the length threshold. In other words, when multiple overlap detection lengths are calculated, the multifeed determination unit 155 determines whether a multifeed of media has occurred based on the average value, maximum value, minimum value, or median of the multiple overlap detection lengths. This allows the multifeed determiner 155 to determine with higher accuracy whether or not a multifeed has occurred.

[0074] Next, the image generation unit 152 reads out each line image generated during medium transport from the storage device 140, 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 S115).

[0075] 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 S116). 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 S116.

[0076] 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 S117), and ends the series of steps.

[0077] It should be noted that, if the processing of steps S111 to S113 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.

[0078] Furthermore, the processing circuit 150 may execute the processes of steps S106 to S113 at predetermined intervals (each time the motor 131 is driven by a predetermined amount) rather than after the entire medium has passed the imaging position of the imaging device 118. In this case, the multifeed determination unit 155 determines that multifeeding of media has not occurred if the overlap length is less than the length threshold until the entire medium has passed the imaging position of the imaging device 118.

[0079] In addition, in step S107, the calculation unit 154 may calculate the overlap detection length along the width direction A2 perpendicular to the medium transport direction, or along both the medium transport direction A1 and the width direction A2 perpendicular to the medium transport direction.

[0080] When calculating the overlap detection length along the width direction A2, the calculation unit 154 calculates the overlap detection length as the length of contiguous overlap detection points in the width direction A2 for each position on the medium that was facing each ultrasonic sensor 115 when the ultrasonic signal was acquired in the medium transport direction A1. However, even if there is a position between two overlap detection points in the width direction A2 where it is determined that no overlap occurs, the calculation unit 154 considers the two overlap detection points to be contiguous if the distance between the two overlap detection points is equal to or less than a reference distance. In other words, the calculation unit 154 determines that one overlap detection point and another overlap detection point are contiguous if the distance between the two overlap detection points is within the reference distance. Note that the reference distance used to calculate the overlap detection length along the width direction A2 may be set to a value different from the reference distance used to calculate the overlap detection length along the medium transport direction A1.

[0081] In this case, in step S108, the multifeed determination unit 155 determines whether a multifeed of media has occurred by determining whether the overlap detection length along the width direction A2 is equal to or greater than a length threshold. Note that the length threshold used to compare the overlap detection length along the width direction A2 may be set to a value different from the length threshold used to compare the overlap detection length along the medium transport direction A1.

[0082] Alternatively, the multifeed determination unit 155 determines whether a multifeed of media has occurred by determining whether the overlap detection length along the medium transport direction A1 and the overlap detection length along the width direction A2 are equal to or greater than a length threshold. In this case, the multifeed determination unit 155 determines that a multifeed of media has occurred if either the overlap detection length along the medium transport direction A1 or the overlap detection length along the width direction A2 is equal to or greater than the length threshold, and determines that a multifeed of media has not occurred if both are less than the length threshold. Alternatively, the multifeed determination unit 155 may determine that a multifeed of media has occurred if both the overlap detection length along the medium transport direction A1 and the overlap detection length along the width direction A2 are equal to or greater than the length threshold, and determine that a multifeed of media has not occurred if either is less than the length threshold. By using the overlap detection lengths along both the medium transport direction A1 and the width direction A2, the multifeed determination unit 155 can more accurately determine whether a multifeed of media has occurred.

[0083] Also in this case, the multifeed determination unit 155 may determine whether a multifeed of media has occurred based on whether a statistical value such as the average value, maximum value, minimum value, or median value of each overlap detection length is equal to or greater than a length threshold value.

[0084] Fig. 8(A) is a schematic diagram illustrating the overlap detection length along the medium transport direction A1, Fig. 8(B) is a schematic diagram illustrating the overlap detection length along the width direction A2, and Fig. 8(C) is a schematic diagram illustrating the distance between each area in the medium that was facing the ultrasonic sensor 115 when the ultrasonic signal was acquired.

[0085] 8(A) and 8(B) show medium 300 conveyed by medium conveying device 100. The area of ​​medium 300 facing ultrasonic sensor 115 when the ultrasonic signal was acquired is represented by a circle, with overlap detection locations represented by black circles and areas where it was determined that no overlap occurred represented by white circles. In the example shown in FIGS. 8(A) and 8(B), as shown in FIG. 8(C), ultrasonic sensors 115 are arranged at intervals ΔX in width direction A2, and ultrasonic signals are acquired at intervals ΔY in medium conveyance direction A1.

[0086] In the examples shown in Figures 8(A) and 8(B), the maximum number of consecutive overlap detection points adjacent to each other in the medium transport direction A1 is 4, and the length is 3ΔY. Also, the maximum number of consecutive overlap detection points adjacent to each other in the width direction A2 is 4, and the length is 3ΔX. Therefore, if the length threshold in the medium transport direction A1 is 4ΔY and the length threshold in the width direction A2 is 4ΔX, it is determined that no double feeding of media has occurred unless overlap detection points whose spacing is less than the reference distance are considered to be consecutive.

[0087] On the other hand, if the reference distance in the medium conveyance direction A1 is 3ΔY and the reference distance in the width direction A2 is 3ΔX, the overlap detection length in the medium conveyance direction A1 is 11ΔY and the overlap detection length in the width direction A2 is 6ΔX. Therefore, it is determined that a double feed of media has occurred. In this way, the medium conveyance device 100 can correctly determine that a double feed of media has occurred even when a double feed of media occurs in which the intensity of the ultrasonic waves transmitted varies from position to position.

[0088] As described above in detail, the medium conveying device 100 of this embodiment determines whether a double feed has occurred based on the overlap detection length over which the overlap detection points are continuous. This enables the medium conveying device 100 to more accurately determine whether a double feed of media has occurred.

[0089] Generally, a medium conveying device may erroneously determine that a multifeed has occurred when a medium with a small adhesive attached is conveyed. By determining whether a multifeed of media has occurred based on the length of an overlapping area within the medium, the medium conveying device 100 can prevent erroneous determinations that a multifeed has occurred when a medium with a small adhesive attached is conveyed. Furthermore, if the distance between multiple overlap detection points is within a predetermined distance, the medium conveying device 100 determines that the multiple overlap detection points are contiguous, thereby enabling highly accurate detection of a multifeed of media in which the intensity of the ultrasonic waves transmitted varies from position to position. In particular, the medium conveying device 100 can calculate the length of an overlapping area within the medium through a simple calculation, thereby reducing the processing load and memory usage of the medium reading process.

[0090] 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.

[0091] 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.

[0092] 6, the overlap detection unit 153 acquires thickness signals from each thickness sensor instead of ultrasonic signals, and stores the signals in association with positions within the medium in the storage device 140. In addition, in step S106, the overlap detection unit 153 reads the signal values ​​of each thickness signal from the storage device 140, and detects, as overlap detection points, each position within the medium that is stored in association with a thickness signal whose signal value is equal to or greater than the overlap threshold.

[0093] 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.

[0094] 9 is a diagram showing a schematic configuration of another processing circuit 250. The processing circuit 250 is used in place of the processing circuit 150 of the medium conveying device 100, and performs the medium reading process, overlap detection process, overlap detection length calculation process, multifeed determination process, and control process in place of the processing circuit 150. The processing circuit 250 has a control circuit 251, an image generation circuit 252, an overlap detection circuit 253, a calculation circuit 254, a multifeed determination circuit 255, etc. Note that each of these components may be configured as an independent integrated circuit, microprocessor, firmware, etc.

[0095] 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 reads out a medium image from the storage device 140. The control circuit 251 outputs a control signal to the motor 131 so as to control the feeding and transport of the medium in accordance with the received or read out information. The control circuit 251 also reads out the result of the determination of a multi-feed from the storage device 140, and executes abnormality processing due to the multi-feed based on the read out determination result.

[0096] 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.

[0097] The overlap detection circuit 253 is an example of an overlap detection unit, and has the same function as the overlap detection unit 153. The overlap detection circuit 253 detects overlap detection points based on ultrasonic signals from the ultrasonic sensor 115, and stores the detection results in the storage device 140.

[0098] The calculation circuit 254 is an example of a calculation unit, and has the same function as the calculation unit 154. The calculation circuit 254 reads out the detection results of the overlap detection points from the storage device 140, calculates the overlap detection length based on the read detection results, and stores the calculated overlap detection length in the storage device 140.

[0099] The multifeed determination circuit 255 is an example of a multifeed determination unit, and has the same function as the multifeed determination unit 155. The multifeed determination circuit 255 reads the overlap detection length from the storage device 140, determines whether or not a multifeed has occurred based on the overlap detection length, and stores the determination result in the storage device 140.

[0100] 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]

[0101] 100 medium conveying device, 103 loading 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 generation unit, 153 overlap detection unit, 154 calculation unit, 155 double feed determination unit

Claims

1. a transport unit that transports the medium; an overlap detection sensor that detects an overlap of the medium transported by the transport unit; a calculation unit that calculates an overlap length of the continuous overlap based on the detection output of the overlap detection sensor; a multifeed determination unit that determines whether or not a multifeed has occurred based on the overlap length; a control unit that executes abnormality processing when it is determined that a double feed has occurred; and the overlap detection sensor performs multi-feed detection at a plurality of positions within the medium; When calculating the overlap length, the calculation unit determines that the first overlapping portion and the second overlapping portion are continuous when a distance between the first overlapping portion and the second overlapping portion is less than a predetermined distance, and the first overlapping portion and the second overlapping portion are portions where an output of the overlap detection sensor indicates an overlap; the predetermined distance is set to a value greater than the distance between adjacent positions among the plurality of positions at which overlap detection is performed; A medium transport device characterized by:

2. The medium transport device of claim 1 , wherein the calculation unit calculates the overlap length along the medium transport direction, along a direction perpendicular to the medium transport direction, or along both the medium transport direction and a direction perpendicular to the medium transport direction.

3. the overlap detection sensor is an ultrasonic sensor that detects the transmission intensity of ultrasonic waves transmitted through a medium; 3. The medium transport device according to claim 1, further comprising an overlap detection unit that compares the transmission intensity detected by the ultrasonic sensor with a predetermined threshold value to determine whether the output of the overlap detection sensor indicates an overlap.

4. The medium transport device according to claim 1 , further comprising an overlap detection unit that determines whether or not the overlapping portion exists at a predetermined interval.

5. 5. The medium transport device according to claim 1, wherein a plurality of the overlap detection sensors are arranged along a direction perpendicular to a transport direction in which the medium is transported.

6. A method for controlling a medium transport device having a transport unit that transports a medium and an overlap detection sensor that performs overlap detection on the medium transported by the transport unit, comprising: calculating an overlap length of the continuous overlap based on the detection output of the overlap detection sensor; determining whether or not a double feed has occurred based on the overlap length; When it is determined that a double feed has occurred, an abnormality process is executed, In calculating the overlap length, if a distance between a first overlapping portion and a second overlapping portion is less than a predetermined distance, the first overlapping portion and the second overlapping portion are determined to be continuous, and the first overlapping portion and the second overlapping portion are portions where an output of the overlap detection sensor indicates an overlap; the predetermined distance is set to a value greater than the distance between adjacent positions among the plurality of positions at which overlap detection is performed; A method for controlling a medium transport device.

7. A control program for a medium conveying device having a conveying unit that conveys a medium and an overlap detection sensor that performs overlap detection on the medium conveyed by the conveying unit, the program comprising: calculating an overlap length of the continuous overlap based on the detection output of the overlap detection sensor; determining whether or not a double feed has occurred based on the overlap length; When it is determined that a double feed has occurred, the medium conveying device is caused to execute an abnormality process; In calculating the overlap length, if a distance between a first overlapping portion and a second overlapping portion is less than a predetermined distance, the first overlapping portion and the second overlapping portion are determined to be continuous, and the first overlapping portion and the second overlapping portion are portions where an output of the overlap detection sensor indicates an overlap; the predetermined distance is set to a value greater than the distance between adjacent positions among the plurality of positions at which overlap detection is performed; A control program for a medium transport device.

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