Medium conveying device, medium conveying method, and control program

Abstract

Provided is a medium conveyance device capable of better executing alignment of the leading end of a medium by a conveyance roller. The medium conveyance device has: a feed roller for feeding the medium; a separation roller disposed opposing the feed roller; the conveyance roller, which is disposed downstream of the feed roller in the direction of medium conveyance, conveys the medium by rotating in a first direction, and executes alignment of the leading end of the medium by stopping or rotating in a second direction opposite to the first direction; and a setting unit for setting a torque to be applied to the separation roller. The setting unit sets the torque to be applied to the separation roller after the conveyance roller starts the alignment of the leading end of the medium to a value smaller than the torque to be applied to the separation roller before the conveyance roller starts the alignment of the leading end of the medium.

Description

[Technical Field]

[0001] The present disclosure relates to a medium transport device, a medium transport method, and a control program, and more particularly to a medium transport device, a medium transport method, and a control program that aligns the leading edge of a medium. [Background technology]

[0002] In media transport devices such as scanners that transport media and capture images, a function has been developed to align the leading edge of the media by rotating the transport rollers that transport the media in the direction that returns the media for a predetermined period of time in order to correct the tilt of the transported media.

[0003] An ADF unit has been disclosed that separates fed documents by applying transport resistance to the separating roller and then transports them to a document reading position (see Patent Document 1). This ADF unit is provided with a load torque generating mechanism that applies a load torque to the separating roller as transport resistance and is configured to be able to change the magnitude of the load torque. The ADF unit changes the load torque generated by the load torque generating mechanism from a first value at the start of paper feeding to a smaller second value after the leading edge of the fed document passes through a registration nip downstream of the separating roller and before it reaches the document reading position. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-180894 Summary of the Invention

[0005] In a media transport device, there is a demand for better alignment of the leading edge of the media by the transport roller.

[0006] A medium conveying device, a medium conveying method, and a control program according to the embodiments aim to more effectively align the leading edge of a medium using a conveyance roller.

[0007] A medium transport device according to one aspect of the embodiment includes a feed roller that feeds a medium, a separation roller that is disposed opposite the feed roller, and a transport roller that is disposed downstream of the feed roller in the medium transport direction, that rotates in a first direction to transport the medium, and that stops or rotates in a second direction opposite to the first direction to align the leading edge of the medium. a motor that generates a driving force for rotating the separation roller and whose torque setting is changeable; a setting unit that sets the torque applied to the separation roller, and after the conveyance roller starts aligning the leading edge of the medium, of motor torque before the transport roller begins to align the leading edge of the media. of motor Set to a value smaller than the torque.

[0008] A medium transport method according to one aspect of the embodiment includes feeding a medium using a feed roller, transporting the medium by rotating in a first direction using a transport roller disposed downstream of the feed roller in the medium transport direction, and aligning the leading edge of the medium by stopping or rotating in a second direction opposite to the first direction, and setting a torque to be applied to a separation roller disposed opposite the feed roller, wherein, in the setting, after the transport roller starts aligning the leading edge of the medium, A motor that generates a driving force for rotating the separation roller and whose torque setting can be changed. torque before the transport roller begins to align the leading edge of the media. of motor Set to a value smaller than the torque.

[0009] A control program according to one aspect of the embodiment includes a feed roller that feeds a medium, a separation roller that is disposed opposite the feed roller, and a transport roller that is disposed downstream of the feed roller in the medium transport direction, that rotates in a first direction to transport the medium, and that stops or rotates in a second direction opposite to the first direction to align the leading edge of the medium. a motor that generates a driving force for rotating the separation roller and whose torque setting is changeable; a control program for a medium conveying device, the control program causing the medium conveying device to set a torque to be applied to a separation roller, and in the setting, after the conveying roller starts aligning the leading edge of the medium, of motor torque before the transport roller begins to align the leading edge of the media. of motor Set to a value smaller than the torque.

[0010] According to this embodiment, the medium transport device, the medium transport method, and the control program are able to more effectively align the leading edge of the medium by the transport roller.

[0011] The objects and advantages of the invention will be realized and obtained by means of the elements and combinations particularly pointed out in the claims. Both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention as claimed. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a perspective view showing a medium conveying device 100 according to an embodiment. [Figure 2] 2 is a diagram for explaining a transport path inside the medium transport device 100. FIG. [Figure 3] 1 is a block diagram showing a schematic configuration of a medium conveying device 100. FIG. [Figure 4] FIG. 2 is a diagram showing a schematic configuration of a storage device 140 and a processing circuit 150. [Figure 5] 10 is a flowchart illustrating an example of the operation of a medium reading process. [Figure 6] 10 is a flowchart illustrating an example of the operation of a medium reading process. [Figure 7] 10 is a graph for explaining a change in speed of the first conveyor roller 116 and the like. [Figure 8] 10A and 10B are schematic diagrams for explaining alignment of the leading edge of a medium. [Figure 9] 10 is a flowchart showing another example of a part of the operation of the medium reading process. [Figure 10] FIG. 10 is a diagram showing a schematic configuration of another processing circuit 250. DETAILED DESCRIPTION OF THE INVENTION

[0013] A medium conveying device, a medium conveying method, and a control program according to one aspect of the present disclosure 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, 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 configured as an image scanner. The medium conveying device 100 conveys a medium, which is an original document, and captures an image. The medium may be paper, thin paper, thick paper, a card, a booklet, or the like. The medium conveying device 100 may also be a facsimile, a copier, a multifunction printer (MFP), or the like. Note that the medium being conveyed may not be an original document, but may be a print target, or the like, and the medium conveying device 100 may also 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, and a display device 106. In Fig. 1, arrow A1 indicates the medium conveying direction, arrow A2 indicates the width direction perpendicular to the medium conveying direction, and arrow A3 indicates the height direction perpendicular to the medium conveying path. In the following, "upstream" refers to the upstream side of the medium conveying direction A1, and "downstream" refers to the downstream side of the medium conveying direction A1.

[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 placement stage 103 engages with the lower housing 101 and places media to be fed and transported on it. The ejection stage 104 engages with the upper housing 102 and places ejected media on it. Note that the ejection stage 104 may also engage with the lower housing 101.

[0018] 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.

[0019] FIG. 2 is a diagram for explaining the transport path inside the medium transport device 100. As shown in FIG.

[0020] The transport path inside the media transport device 100 includes a first media sensor 111, a feed roller 112, a separation roller 113, a second media sensor 114, a third media sensor 115, a first transport roller 116, a first driven roller 117, a fourth media sensor 118, an imaging device 119, a fifth media sensor 120, a second transport roller 121, and a second driven roller 122, etc.

[0021] The number of each of the feed roller 112, separation roller 113, first conveyance roller 116, first driven roller 117, second conveyance roller 121, and / or second driven roller 122 is not limited to one, and may be more than one. In this case, the multiple feed rollers 112, separation rollers 113, first conveyance roller 116, first driven roller 117, second conveyance roller 121, and / or second driven roller 122 are arranged at intervals in the width direction A2, which is perpendicular to the medium conveyance direction.

[0022] The top surface of the lower housing 101 forms a lower guide 101a of the medium transport path, and the bottom surface of the upper housing 102 forms an upper guide 102a of the medium transport path.

[0023] The first medium sensor 111 is disposed upstream of the feed roller 112 and the separation roller 113. The first medium sensor 111 has a contact detection sensor and detects whether or not a medium is placed on the placement table 103. The first medium 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. Note that the first medium sensor 111 is not limited to a contact detection sensor, and any other sensor capable of detecting the presence or absence of a medium, such as an optical detection sensor, may be used as the first medium sensor 111.

[0024] The feed roller 112 is provided in the lower housing 101. The feed roller 112 is provided rotatably in a medium feed direction A4, and separates and feeds the media placed on the mounting table 103 sequentially from the bottom. The separation roller 113 is a so-called brake roller or retard roller, and is provided in the upper housing 102 and disposed opposite to the feed roller 112. The separation roller 113 is provided rotatably or stoppably in a direction A5 opposite the medium feed direction. Alternatively, the feed roller 112 may be provided in the upper housing 102 and the separation roller 113 in the lower housing 101, and the feed roller 112 may feed the media placed on the mounting table 103 sequentially from the top.

[0025] The second media sensor 114 is located downstream of the feed roller 112 and upstream of the first transport roller 116, particularly near the feed roller 112, and detects media transported to that position. The second media sensor 114 includes a light emitter and a light receiver located on one side of the media transport path, and a light guide located opposite the light emitter and light receiver across the media transport path. The light emitter is an LED (Light Emitting Diode) or the like and emits light toward the media transport path. The light receiver is a photodiode or the like and receives light emitted by the light emitter and guided by the light guide. When a medium is present in a position opposite the second media sensor 114, the light emitted from the light emitter is blocked by the medium, and the light receiver does not detect the light emitted from the light emitter. The second media sensor 114 generates and outputs a second media signal whose signal value changes depending on whether a medium is present or not at the second media sensor 114, based on the intensity of the light received by the light receiver.

[0026] A reflective member such as a mirror may be used instead of the light guide tube. The light emitter and the light receiver may be disposed opposite each other across the medium transport path. The second medium sensor 114 may detect the presence of the medium using a contact detection sensor that passes a predetermined current when the medium is in contact or when the medium is not in contact.

[0027] The third media sensor 115 is located downstream of the second media sensor 114 and upstream of the first transport roller 116, particularly near the first transport roller 116, and detects media transported to that position. The third media sensor 115 includes a light emitter and a light receiver located on one side of the media transport path, and a light guide located opposite the light emitter and light receiver across the media transport path. The light emitter is an LED or the like and emits light toward the media transport path. The light receiver is a photodiode or the like and receives light emitted by the light emitter and guided by the light guide. When a medium is present in a position opposite the third media sensor 115, the light emitted from the light emitter is blocked by the medium, and the light receiver does not detect the light emitted from the light emitter. The third media sensor 115 generates and outputs a third media signal whose signal value changes depending on whether a medium is present or not at the third media sensor 115, based on the intensity of the light received by the light receiver.

[0028] A reflective member such as a mirror may be used instead of the light guide tube. The light emitter and the light receiver may be disposed opposite each other across the medium transport path. Third medium sensor 115 may detect the presence of a medium using a contact detection sensor that passes a predetermined current when the medium is in contact or when the medium is not in contact.

[0029] The first conveying roller 116 and the first driven roller 117 are disposed facing each other downstream of the feeding roller 112 and the separation roller 113 in the medium conveying direction A1. The first conveying roller 116 is provided in the upper housing 102, and conveys the medium fed by the feeding roller 112 and the separation roller 113 to the imaging device 119. Note that the first conveying roller 116 may be provided in the lower housing 101, and the first driven roller 117 may be provided in the upper housing 102.

[0030] The first conveyance roller 116 is an example of a conveyance roller. The first conveyance roller 116 conveys the fed medium downstream by rotating in a forward direction A6, which applies a force to the medium toward the downstream side. On the other hand, the first conveyance roller 116 stops the advance of the leading edge of the fed medium and aligns the leading edge of the medium by stopping or rotating in a reverse direction A7, which applies a force to the medium toward the upstream side. In other words, the first conveyance roller 116 functions as a registration roller that corrects the tilt of the leading edge of the fed medium by stopping or rotating in the reverse direction A7. The forward direction A6 is an example of a first direction, and the reverse direction A7 is an example of a second direction opposite to the first direction. When the first conveyance roller 116 rotates in the forward direction A6, the first driven roller 117 rotates in the forward direction A8, driven by the first conveyance roller 116. On the other hand, when the first conveyor roller 116 rotates in the reverse direction A7, the first driven roller 117 rotates in the reverse direction A9, following the first conveyor roller 116.

[0031] The fourth medium sensor 118 is disposed downstream of the first transport roller 116 and upstream of the imaging device 119, and detects media transported to that position. The fourth medium sensor 118 includes a light emitter and a light receiver provided on one side of the media transport path, and a light guide tube provided opposite the light emitter and light receiver across the media transport path. The light emitter is an LED or the like, and emits light toward the media transport path. Meanwhile, the light receiver is a photodiode or the like, and receives the light emitted by the light emitter and guided by the light guide tube. The fourth medium sensor 118 generates and outputs a fourth medium signal, the signal value of which changes depending on whether a medium is present or absent at the position of the fourth medium sensor 118, based on the intensity of the light received by the light receiver.

[0032] A reflective member such as a mirror may be used instead of the light guide tube. The light emitter and the light receiver may be disposed opposite each other across the medium transport path. The fourth medium sensor 118 may detect the presence of a medium using a contact detection sensor that passes a predetermined current when the medium is in contact or when the medium is not in contact.

[0033] The imaging device 119 is an example of an imaging section, and is arranged downstream of the first transport roller 116 and upstream of the second transport roller 121 in the medium transport direction A1, and captures images of the medium transported by the first transport roller 116 and the first driven roller 117. The imaging device 119 includes a first imaging device 119a and a second imaging device 119b arranged opposite each other across the medium transport path.

[0034] The first imaging device 119a 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 arranged linearly in the main scanning direction. The first imaging device 119a also has 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 119a captures an image of the surface of the transported medium under control of a processing circuit (described later), generates an input image, and outputs it.

[0035] Similarly, the second imaging device 119b has a CIS line sensor with a life-size optical system having CMOS imaging elements linearly arranged in the main scanning direction. The second imaging device 119b also has 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 119b captures an image of the back side of the transported medium under control of a processing circuit (described later), generating an input image, and outputting it.

[0036] Note that medium conveying device 100 may have only one of first imaging device 119a and second imaging device 119b disposed, 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.

[0037] The fifth media sensor 120 is disposed downstream of the imaging device 119 and upstream of the second transport roller 121, and detects media transported to that position. The fifth media sensor 120 includes a light emitter and a light receiver provided on one side of the media transport path, and a light guide tube provided opposite the light emitter and light receiver across the media transport path. The light emitter is an LED or the like, and emits light toward the media transport path. Meanwhile, the light receiver is a photodiode or the like, and receives the light emitted by the light emitter and guided by the light guide tube. The fifth media sensor 120 generates and outputs a fifth media signal based on the intensity of the light received by the light receiver. The signal value changes depending on whether a media is present or absent at the position of the fifth media sensor 120.

[0038] A reflective member such as a mirror may be used instead of the light guide tube. The light emitter and the light receiver may be disposed opposite each other across the medium transport path. The fifth medium sensor 120 may detect the presence of a medium using a contact detection sensor that passes a predetermined current when the medium is in contact or when the medium is not in contact.

[0039] The second conveying roller 121 and the second driven roller 122 are arranged facing each other in the medium conveying direction A1, downstream from the imaging device 119, i.e., downstream from the first conveying roller 116 and the first driven roller 117. The second conveying roller 121 is provided in the upper housing 102, and conveys the medium conveyed by the first conveying roller 116 and the first driven roller 117 further downstream and discharges it onto the discharge tray 104. Note that the second conveying roller 121 may be provided in the lower housing 101, and the second driven roller 122 may be provided in the upper housing 102.

[0040] The media placed on the mounting table 103 are transported between the lower guide 101a and the upper guide 102a in the media transport direction A1 as the feed roller 112 rotates in the media feed direction A4. The medium transport device 100 has two feeding modes: a separation mode in which the media are separated while being fed, and a non-separation mode in which the media are fed without being separated. The feed mode is set by the user using the operation device 105 or an information processing device that is communicatively connected to the medium transport device 100. When the feeding mode is set to the separation mode, the separation roller 113 rotates in the direction A5 opposite the media feed direction or stops. When multiple media are placed on the mounting table 103, the feed roller 112 and the separation roller 113 function to separate only the media that are in contact with the feed roller 112 from the media placed on the mounting table 103. This restricts the transport of media other than the separated media (preventing double feeding). On the other hand, when the feeding mode is set to the non-separation mode, the separation roller 113 rotates in the medium feeding direction (the opposite direction to the arrow A5).

[0041] The medium is guided by the lower guide 101a and the upper guide 102a and fed into the nip between the first conveyor roller 116 and the first driven roller 117. The first conveyor roller 116 and the first driven roller 117 rotate in the reverse directions A7 and A9, respectively, for a certain period of time, causing the leading edge of the medium to be held in the nip between the first conveyor roller 116 and the first driven roller 117. During this time, the medium is pushed out by the feed roller 112, and the leading edge of the medium is aligned. The first conveyor roller 116 and the first driven roller 117 then rotate in the forward directions A6 and A8, respectively, causing the medium to be fed between the first image capture device 119a and the second image capture device 119b. The medium scanned by the image capture device 119 is then ejected onto the ejection tray 104 by the second conveyor roller 121 and the second driven roller 122 rotating in the directions of arrows A10 and A11, respectively.

[0042] As shown in FIG. 2, the medium conveying device 100 also has a first motor 131, a second motor 132, and a third motor 133 as drive sources for the rollers.

[0043] The first motor 131 is provided in the lower housing 101, and is connected to the feed roller 112 via a first transmission mechanism 131a to drive the feed roller 112. The first motor 131 generates a driving force for rotating the feed roller 112 in response to a control signal from the processing circuit, thereby feeding the medium. The first motor 131 may be disposed in the upper housing 102.

[0044] The first transmission mechanism 131a includes one or more pulleys, belts, gears, etc. arranged between the first motor 131 and the shaft 112a, which is the rotation axis of the feed roller 112, and transmits the driving force generated by the first motor 131 to the feed roller 112.

[0045] The second motor 132 is an example of a motor. The second motor 132 is provided in the upper housing 102 separately from the first motor 131, and is connected to the separation roller 113 via a second transmission mechanism 132a to drive the separation roller 113. The second motor 132 generates a driving force for rotating the separation roller 113 in response to a control signal from the processing circuit, causing the separation roller 113 to separate, feed, and transport the medium. The second motor 132 may be provided in the lower housing 101. The second motor 132 is, for example, a DC motor such as a brushed DC (Direct Current) motor. Note that the second motor 132 may also be another DC motor such as a brushless DC motor, or a stepping motor. The second motor 132 is provided so that the torque setting can be changed according to the supplied power.

[0046] The greater the amount of current supplied to the DC motor or stepping motor, i.e., the greater the amount of power supplied to the DC motor or stepping motor, the greater the torque of the DC motor or stepping motor. Conversely, the smaller the amount of current supplied to the DC motor or stepping motor, i.e., the smaller the amount of power supplied to the DC motor or stepping motor, the smaller the torque of the DC motor or stepping motor. Therefore, the medium conveying device 100 can change the torque of the second motor 132 by changing the amount of power supplied to the second motor 132. The medium conveying device 100 can increase the torque of the second motor 132 by increasing the amount of power supplied to the second motor 132, thereby increasing the torque applied to the separation roller 113 (the load component applied by the separation roller 113 to the medium). On the other hand, the medium conveying device 100 can decrease the torque of the second motor 132 by decreasing the amount of power supplied to the second motor 132, thereby decreasing the torque applied to the separation roller 113 (the load component applied by the separation roller 113 to the medium).

[0047] The second transmission mechanism 132a includes one or more pulleys, belts, gears, etc., provided between the second motor 132 and the shaft 113a which is the rotation axis of the separation roller 113. The second transmission mechanism 132a transmits the driving force generated by the second motor 132 to the separation roller 113.

[0048] The medium conveying device 100 further includes a torque limiter 113b. The torque limiter 113b is provided between the second motor 132 and the separation roller 113. In the example shown in FIG. 2, the torque limiter 113b is disposed on the shaft 113a, which is the rotation axis of the separation roller 113. The torque limiter 113b defines a limit value for the torque applied to the separation roller 113. The limit value of the torque limiter 113b is set to a value such that the rotational force via the torque limiter 113b is cut off when there is one medium, and such that the rotational force via the torque limiter 113b is transmitted when there are multiple media. As a result, when only one medium is being conveyed, the separation roller 113 does not rotate according to the driving force from the second motor 132, but instead rotates in accordance with the feed roller 112. On the other hand, when multiple media are being transported, the separation roller 113 rotates in the direction A5 opposite the medium feeding direction to separate the medium in contact with the feeding roller 112 from other media, preventing double feeding. At this time, the outer circumferential surface of the separation roller 113 may apply a force to the media in the direction A5 opposite the medium feeding direction while remaining stationary and not rotating in the direction A5 opposite the medium feeding direction.

[0049] The third motor 133 is provided in the upper housing 102 separately from the first motor 131 and the second motor 132. The third motor 133 is connected to the first transport roller 116 and the second transport roller 121 via a third transmission mechanism 133a, and drives the first transport roller 116 and the second transport roller 121. The third motor 133 generates a driving force for rotating the first transport roller 116 and the second transport roller 121 in response to a control signal from the processing circuit, causing the first transport roller 116 and the second transport roller 121 to transport and discharge the medium. The third motor 133 may be disposed in the lower housing 101.

[0050] The third transmission mechanism 133a includes one or more pulleys, belts, gears, etc., provided between the third motor 133 and the shaft 116a, which is the rotation shaft of the first conveyor roller 116, and the shaft 121a, which is the rotation shaft of the second conveyor roller 121. The third transmission mechanism 133a transmits the driving force generated by the third motor 133 to the first conveyor roller 116 and the second conveyor roller 121.

[0051] In this way, in the medium conveying device 100, the third motor 133 is used in common as the motor for driving the first conveying roller 116 and the motor for driving the second conveying roller 121. This allows the medium conveying device 100 to reduce the number of motors, thereby reducing the cost, size, and weight of the device.

[0052] The first driven roller 117 is a driven roller that rotates following the first conveyor roller 116, and the second driven roller 122 is a driven roller that rotates following the second conveyor roller 121. The first driven roller 117 and / or the second driven roller 122 may be driven by a driving force from a third motor 133. In this case, one or more gears are further provided between the shaft 116a of the first conveyor roller 116 and the shaft 117a that is the rotation axis of the first driven roller 117 and / or between the shaft 121a of the second conveyor roller 121 and the shaft 122a that is the rotation axis of the second driven roller 122. The third transmission mechanism 133a further transmits the driving force generated by the third motor 133 to the first driven roller 117 and / or the second driven roller 122.

[0053] FIG. 3 is a block diagram showing a schematic configuration of the medium conveying device 100. As shown in FIG.

[0054] In addition to the components described above, the medium transport device 100 further includes an interface device 134, a storage device 140, a processing circuit 150, and the like.

[0055] The interface device 134 has an interface circuit conforming to a serial bus such as USB, and is electrically connected to an information processing device (not shown) (e.g., a personal computer, a portable information terminal, etc.) to transmit and receive input images and various information. Alternatively, instead of the interface device 134, 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 may be used. The predetermined communication protocol is, for example, a wireless LAN (Local Area Network). The communication unit may have a wired communication interface device for transmitting and receiving signals via a wired communication line in accordance with a communication protocol such as a wired LAN.

[0056] 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 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.

[0057] The processing circuit 150 operates based on a program stored in advance in the storage device 140. The processing circuit 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.

[0058] The processing circuit 150 is connected to the operation device 105, the display device 106, the first medium sensor 111, the second medium sensor 114, the third medium sensor 115, the fourth medium sensor 118, the imaging device 119, the fifth medium sensor 120, the first motor 131, the second motor 132, the third motor 133, the interface device 134, the storage device 140, and the like, and controls each of these components. The processing circuit 150 controls the drive of each motor and the imaging of the imaging device 119 based on each medium signal received from each medium sensor. The processing circuit 150 acquires an input image from the imaging device 119 and transmits it to the information processing device via the interface device 134. The processing circuit 150 also sets the torque to be applied to the separation roller 113 based on each medium signal received from each medium sensor.

[0059] FIG. 4 is a diagram showing a schematic configuration of the storage device 140 and the processing circuit 150. As shown in FIG.

[0060] 4, the storage device 140 stores a control program 141, a setting program 142, and the like. Each of these programs is a functional module implemented by software running on a processor. The processing circuitry 150 reads each program stored in the storage device 140 and operates in accordance with the read program. As a result, the processing circuitry 150 functions as a control unit 151 and a setting unit 152.

[0061] 5 and 6 are flowcharts showing an example of the operation of the medium reading process of the medium conveying device 100. FIG.

[0062] 5 and 6, an example of the operation of the medium reading process of the medium conveying device 100 will be described. Note that 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 stored in advance in the storage device 140.

[0063] First, the control unit 151 waits until the user inputs an instruction to read a medium using the operation device 105 or the information processing device, and an operation signal instructing the reading of a medium is received from the operation device 105 or the interface device 134 (step S101).

[0064] Next, control unit 151 acquires a first medium signal from first medium sensor 111, and determines whether or not a medium is placed on mounting table 103 based on the acquired first medium signal (step S102). If no medium is placed on mounting table 103, control unit 151 ends the series of steps.

[0065] On the other hand, if a medium is placed on the placement table 103, the setting unit 152 sets the torque of the second motor 132 to a first torque value (step S103). The setting unit 152 sets the amount of power (current) supplied to the second motor 132 to the amount of power (current) corresponding to the first torque value, thereby setting the torque of the second motor 132 to the first torque value. The first torque value is set to a value greater than the limit value of the torque limiter 113b. Because the torque of the second motor 132 exceeds the limit value of the torque limiter 113b, the torque applied to the separation roller 113 is limited to the limit value of the torque limiter 113b. In other words, the setting unit 152 sets the torque applied to the separation roller 113 to the limit value of the torque limiter 113b, and sets the load component applied by the separation roller 113 to the limit value of the torque limiter 113b.

[0066] Next, the control unit 151 drives the first motor 131 and the second motor 132 to rotate the feed roller 112 and the separation roller 113 and feed the medium (step S104). The control unit 151 rotates the feed roller 112 in the medium feed direction A4, and rotates the separation roller 113 in a direction A5 opposite to the medium feed direction.

[0067] FIG. 7 is a graph for explaining the speed changes of the feed roller 112, the separation roller 113, and the first conveyor roller 116. In FIG.

[0068] 7, graph G11 shows the change in speed of the feed roller 112, graph G12 shows the change in speed of the separation roller 113, and graph G13 shows the change in speed of the first conveyor roller 116. The speeds of the first driven roller 117, second conveyor roller 121, and second driven roller 122 change in the same way as the speed of the first conveyor roller 116, so below we will explain the change in speed of the first conveyor roller 116 as a representative. The horizontal axis of each of graphs G11 to G13 represents time, and the vertical axis represents speed. The speed of each roller is the moving speed of the surface of each roller (the speed at which the medium is conveyed by each roller).

[0069] Meanwhile, graph G14 shows the change in the signal value of the second medium sensor 114, graph G15 shows the change in the signal value of the third medium sensor 115, graph G16 shows the change in the signal value of the fourth medium sensor 118, and graph G17 shows the change in the signal value of the fifth medium sensor 120. The horizontal axis of each of graphs G14, G15, G16, and G17 represents time, and the vertical axis represents the signal value. In this embodiment, when no medium is present at each sensor, the signal value of the corresponding signal is L, and when a medium is present at each sensor, the signal value of the corresponding signal is H.

[0070] In FIG. 7, time T1 indicates the start of medium feeding. As shown in FIG. 7, when medium feeding starts, the control unit 151 sets the speed of the feed roller 112 to an initial speed V1. The initial speed V1 is set to a speed that is sufficiently lower than the intermediate speed V2 and final speed V3, which will be described later. By setting the speed of the feed roller 112 at the start of medium feeding to a sufficiently low speed, the control unit 151 can reliably separate the media and prevent the occurrence of double feeding of media. Meanwhile, the control unit 151 sets the speed of the separation roller 113 to a speed U. Thereafter, the speed of the separation roller 113 does not change from speed U. In addition, the control unit 151 sets the speed of the first conveyor roller 116 to 0, and does not rotate the first conveyor roller 116.

[0071] 7, after a predetermined through-up period has elapsed since the start of driving each motor at time T1, each roller rotates at the set speed. Similarly, if control unit 151 subsequently changes the speed of each roller, each roller rotates at the set speed after a predetermined through-up period or through-down period has elapsed since the speed of each roller was changed.

[0072] Next, the control unit 151 waits until the leading edge of the fed medium passes the nip portion between the feed roller 112 and the separation roller 113 (step S105). Hereinafter, the nip portion between the feed roller 112 and the separation roller 113 may be referred to as the separation portion. The control unit 151 periodically acquires a second medium signal from the second medium sensor 114, and determines that the leading edge of the medium has passed the position of the second medium sensor 114 when the signal value of the second medium signal changes from a value indicating that the medium is not present to a value indicating that the medium is present. The control unit 151 determines that the leading edge of the medium has passed the separation portion when the leading edge of the medium has passed the position of the second medium sensor 114. Note that the control unit 151 may also determine that the leading edge of the medium has passed the separation portion when a predetermined time has elapsed since the start of feeding of the medium.

[0073] Next, the control unit 151 changes the speed of the feeding roller 112 (step S106).

[0074] 7, time T2 indicates the time when the signal value of the second medium signal changes from L to H, i.e., the time when the leading edge of the medium passes through the separation section. As shown in FIG. 7, at time T2, the control unit 151 changes the speed of the feed roller 112 from the initial speed V1 to the intermediate speed V2. The intermediate speed V2 is set to a speed that is higher than the initial speed V1 and lower than the final speed V3, which will be described later. By increasing the speed of the feed roller 112 when the leading edge of the medium passes through the separation section, the control unit 151 can shorten the time from when the leading edge of the medium passes through the separation section until it reaches the position of the first conveyor roller 116, and can shorten the processing time for the medium reading process.

[0075] Next, the control unit 151 controls the third motor 133 to stop the first conveyor roller 116 (step S107).

[0076] As shown in FIG. 7, the control unit 151 stops the first conveyor roller 116 (changes the speed to 0) at time T2 when the leading edge of the medium passes through the separation unit. However, when the leading edge of the first medium to be fed among the media placed on the mounting table 103 passes through the separation unit, the first conveyor roller 116 is not yet rotating. Therefore, when the first medium is fed, the processing of step S107 may be omitted. The control unit 151 aligns the leading edge of the medium by stopping or reversely rotating the first conveyor roller 116 when the leading edge of the medium reaches the position of the first conveyor roller 116 in the processing described below. By stopping the first conveyor roller 116 when the leading edge of the medium passes through the separation unit, taking the through-down period into consideration, the control unit 151 can reliably stop the leading edge of the medium when it reaches the position of the first conveyor roller 116.

[0077] Next, the control unit 151 waits until the leading edge of the fed medium reaches the nip portion between the first conveyor roller 116 and the first driven roller 117 (step S108). Hereinafter, the nip portion between the first conveyor roller 116 and the first driven roller 117 may be referred to as the conveyance portion. The control unit 151 periodically acquires a third medium signal from the third medium sensor 115, and determines that the leading edge of the medium has passed the position of the third medium sensor 115 when the signal value of the third medium signal changes from a value indicating that the medium is not present to a value indicating that the medium is present. The control unit 151 determines that the leading edge of the medium has reached the front of the conveyance portion when the leading edge of the medium has passed the position of the third medium sensor 115. Note that the control unit 151 may also determine that the leading edge of the medium has reached the front of the conveyance portion when a predetermined time has elapsed since feeding of the medium began.

[0078] Next, the setting unit 152 sets the torque of the second motor 132 to a second torque value (step S109). The setting unit 152 sets the amount of power (current) supplied to the second motor 132 to the amount of power (current) corresponding to the second torque value, thereby setting the torque of the second motor 132 to the second torque value. The second torque value is set to a value smaller than the limit value of the torque limiter 113b. Because the torque of the second motor 132 is smaller than the limit value of the torque limiter 113b, a torque of the second torque value is applied to the separation roller 113 by the second motor 132. In other words, the setting unit 152 sets the torque applied to the separation roller 113 to the second torque value, and sets the load component applied by the separation roller 113 to the second torque value.

[0079] Next, the control unit 151 changes the speed of the feeding roller 112 (step S110).

[0080] 7, time T3 indicates the time when the signal value of the third medium signal changes from L to H, i.e., the time when the leading edge of the medium reaches the front of the conveying section. As shown in FIG. 7, the control unit 151 changes the speed of the feed roller 112 from the intermediate speed V2 to the final speed V3. The final speed V3 is set to a speed higher than the initial speed V1 and the intermediate speed V2. By increasing the speed of the feed roller 112 when the leading edge of the medium reaches the front of the conveying section, the control unit 151 can more strongly abut the leading edge of the medium against the first conveying roller 116 and / or the first driven roller 117, thereby more effectively aligning the leading edge of the medium.

[0081] Next, the control unit 151 controls the third motor 133 so as to stop the first conveyor roller 116 or rotate it in the reverse direction A7 (step S111).

[0082] As shown in FIG. 7, at time T3 when the leading edge of the medium reaches the front of the conveyance unit, the control unit 151 rotates the first conveyance roller 116 in the reverse direction A7 (changes the speed to a negative value). At this time, the first driven roller 117 rotates in the reverse direction A9, driven by the first conveyance roller 116. In the example shown in FIG. 7, the control unit 151 rotates the first conveyance roller 116 in the reverse direction A7 at time T3, but the control unit 151 may also stop the first conveyance roller 116 (changes the speed to 0). In that case, the first driven roller 117 stops, driven by the first conveyance roller 116.

[0083] Next, the control unit 151 waits until a predetermined time has elapsed, and then causes the first conveyor roller 116 to align the leading edge of the medium (step S112). The predetermined time is set to the maximum or average value of the time required for the medium to be stopped by the first conveyor roller 116 and the first driven roller 117 and for the tilt of the medium to be corrected (eliminated) in an experiment in which various types of medium were fed at various tilt angles.

[0084] FIG. 8 is a schematic diagram for explaining alignment of the leading edge of the medium.

[0085] In the example shown in FIG. 8, multiple media M1 to M4 are collectively placed on the placement table 103. As shown in FIG. 8, of the media M1 to M4 placed on the placement table 103, only the medium M1 in contact with the feed roller 112 is separated and fed, and reaches the nip portion between the first conveyor roller 116 and the first driven roller 117. At this time, the first conveyor roller 116 and the first driven roller 117 stop or rotate in the reverse directions A7 and A9, and the advance of the leading edge of the medium M1 is blocked by the first conveyor roller 116 and the first driven roller 117. Meanwhile, the feed roller 112 continues to push the medium M1 downstream, and the medium M1 is pushed downstream while bending upward. As a result, when the medium M1 is fed at an angle with respect to the width direction A2, the leading edge of the medium M1 is positioned along the width direction A2 at the nip portion between the first conveyor roller 116 and the first driven roller 117. Therefore, the control unit 151 can correct the skew of the medium by stopping the first transport roller 116 or rotating it in the reverse direction A7 for a predetermined time.

[0086] As described above, in step S103, the setting unit 152 sets the torque applied to the separation roller 113 when medium feeding starts to the limit value of the torque limiter 113b. Meanwhile, in step S109, the setting unit 152 sets the torque applied to the separation roller 113 when aligning the leading edge of the medium to a second torque value that is smaller than the limit value of the torque limiter 113b. That is, the setting unit 152 sets the torque applied to the separation roller 113 after the first conveyor roller 116 starts aligning the leading edge of the medium to a value that is smaller than the torque applied to the separation roller 113 before the first conveyor roller 116 starts aligning the leading edge of the medium.

[0087] As a result, the separation roller 113 can impart a sufficiently large load component to the media placed on the mounting table 103 at the start of medium feeding, allowing the media to be separated well. On the other hand, the separation roller 113 reduces the load component that it imparts to media that have completed separation and whose leading edges are being aligned, thereby reducing the force with which the media are held between the feed roller 112 and the separation roller 113. As a result, the media whose leading edges are being aligned can move more easily in the nip portion between the feed roller 112 and the separation roller 113, allowing the control unit 151 to more efficiently correct skew in the media.

[0088] In particular, the setting unit 152 sets the torque of the second motor 132 before the first conveyor roller 116 starts aligning the leading edge of the medium to a first torque value that is greater than the limit value of the torque limiter 113b. On the other hand, the setting unit 152 sets the torque of the second motor 132 after the first conveyor roller 116 starts aligning the leading edge of the medium to a second torque value that is less than the limit value of the torque limiter 113b. This allows the setting unit 152 to reliably set the torque applied to the separation roller 113 at the start of medium feeding, i.e., during medium separation, to the torque value required to separate the medium, thereby enabling the medium to be separated satisfactorily.

[0089] Next, the control unit 151 controls the third motor 133 to rotate the first conveyor roller 116 in the forward direction A6 (step S113).

[0090] As shown in FIG. 7, the control unit 151 rotates the first conveyor roller 116 in the forward direction A6 (changes the speed to a positive value) when a predetermined time P1 has elapsed since time T3 when the leading edge of the medium reaches the front of the conveyance unit. At this time, the first driven roller 117 rotates in the forward direction A8, driven by the first conveyor roller 116. The control unit 151 sets the speed of the first conveyor roller 116 to speed W. The speed W of the first conveyor roller 116 is set to a speed higher than the final speed V3 of the feed roller 112. This allows the control unit 151 to quickly eliminate any sagging of the medium that occurs while the first conveyor roller 116 is aligning the leading edge of the medium. The speed W of the first conveyor roller 116 may be set to a speed equal to or lower than the final speed V3 of the feed roller 112.

[0091] Next, the control unit 151 waits until the leading edge of the fed medium passes the conveyance unit (step S114). The control unit 151 periodically acquires a fourth medium signal from the fourth medium sensor 118, and determines that the leading edge of the medium has passed the position of the fourth medium sensor 118 when the signal value of the fourth medium signal changes from a value indicating that the medium is not present to a value indicating that the medium is present. The control unit 151 determines that the leading edge of the medium has passed the position of the fourth medium sensor 118 when the leading edge of the medium has passed the position of the fourth medium sensor 118. Note that the control unit 151 may also determine that the leading edge of the medium has passed the conveyance unit when a predetermined time has elapsed since the first conveyance roller 116 was rotated in the forward direction A6.

[0092] Next, the control unit 151 causes the imaging device 119 to start imaging the medium (step S115).

[0093] 7, time T4 indicates the time when the signal value of the fourth medium signal changes from L to H, i.e., the time when the leading edge of the medium passes the transport section. By causing imaging device 119 to start capturing an image of the medium when the leading edge of the medium passes the transport section, control unit 151 can cause imaging device 119 to start capturing an image of the medium just before the medium reaches the imaging position of imaging device 119. Therefore, control unit 151 can suppress an increase in the area in which the background appears in the input image, and suppress an increase in the data amount of the input image.

[0094] Next, the control unit 151 waits until the leading edge of the conveyed medium passes through the nip portion between the second conveyance roller 121 and the second driven roller 122 (step S116). Hereinafter, the nip portion between the second conveyance roller 121 and the second driven roller 122 may be referred to as the discharge portion. The control unit 151 periodically acquires a fifth medium signal from the fifth medium sensor 120, and determines that the leading edge of the medium has passed through the discharge portion when the signal value of the fifth medium signal changes from a value indicating that the medium is not present to a value indicating that the medium is present. Note that the control unit 151 may also determine that the leading edge of the medium has passed through the discharge portion when a predetermined time has elapsed since the first conveyance roller 116 was rotated in the forward direction A6.

[0095] Next, the setting unit 152 sets the torque of the second motor 132 to the first torque value (step S117). That is, similar to the processing of step S103, the setting unit 152 sets the torque applied to the separation roller 113 to the limit value of the torque limiter 113b, and sets the load component applied by the separation roller 113 to the limit value of the torque limiter 113b.

[0096] 7, time T5 indicates the time when the signal value of the fifth medium signal changes from L to H, i.e., the time when the leading edge of the medium passes through the discharge section. When the leading edge of the medium passes through the discharge section, i.e., when the medium being conveyed is securely sandwiched between the second conveying roller 121 and the second driven roller 122, the setting unit 152 returns the torque applied to the separation roller 113 to the limit value of the torque limiter 113b. This resets the torque applied to the separation roller 113 to a torque value appropriate for separating the media, and the medium conveying device 100 can prevent double feeding of media.

[0097] In this way, the setting unit 152 sets the torque applied to the separation roller 113 during the period P2 from time T3 when the leading edge of the medium arrives in front of the conveying unit to time T5 when the leading edge of the medium passes the discharge unit to a value smaller than the torque applied to the separation roller 113 during periods other than period P2. In other words, the setting unit 152 sets the torque applied to the separation roller 113 from when the first conveying roller 116 starts aligning the leading edge of the medium until the leading edge of the medium passes the position of the second conveying roller 121 to a value smaller than the torque applied to the separation roller 113 before the first conveying roller 116 starts aligning the leading edge of the medium.

[0098] As described above, the first conveyor roller 116 aligns the leading edge of the medium, causing the medium to bend upward. If the torque applied to the separation roller 113 is increased when the medium is in a bent-up state, a large load is placed on the medium, which may cause wrinkles. The setting unit 152 increases (returns) the torque applied to the separation roller 113 after the leading edge of the medium passes the position of the second conveyor roller 121. By increasing the torque applied to the separation roller 113 when the medium is no longer bent, the setting unit 152 can prevent wrinkles from occurring in the medium. Furthermore, by increasing the torque applied to the separation roller 113 when the medium is sandwiched between the first conveyor roller 116 and the second conveyor roller 121 and is stable, the setting unit 152 can reduce the effect of the load on the medium and prevent wrinkles from occurring in the medium.

[0099] Next, the control unit 151 controls the first motor 131 to stop the feeding roller 112 (step S118).

[0100] 7, the control unit 151 stops the feed roller 112 (changes the speed to 0) at time T5 when the leading edge of the medium passes the discharge unit. As a result, the medium is subsequently transported by the first transport roller 116 and the second transport roller 121, and the feed roller 112 rotates along with the transported medium. By stopping the feed roller 112, the control unit 151 can prevent the medium from being pushed by the feed roller 112 and bending between the feed roller 112 and the first transport roller 116, which can cause a medium jam.

[0101] Next, control unit 151 determines whether or not a medium remains on mounting table 103 based on the first medium signal received from first medium sensor 111 (step S119).

[0102] If a medium remains on the mounting table 103, the control unit 151 waits until the trailing end of the transported medium passes the separation unit (step S120). The control unit 151 periodically acquires a second medium signal from the second medium sensor 114, and determines that the trailing end of the medium has passed the position of the second medium 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 trailing end of the medium has passed the separation unit when the trailing end of the medium has passed the position of the second medium sensor 114. Note that the control unit 151 may also determine that the trailing end of the medium has passed the separation unit when a predetermined time has elapsed since the start of feeding the medium.

[0103] Next, the control unit 151 drives the first motor 131 to rotate the feed roller 112 and feed the subsequent medium (step S121). Similar to the process of step S104, the control unit 151 sets the speed of the feed roller 112 to the initial speed V1 and rotates the feed roller 112 in the medium feed direction A4.

[0104] 7, time T6 indicates the time when the signal value of the second medium signal changes from H to L, i.e., the time when the trailing edge of the medium passes through the separation unit. When the trailing edge of the preceding medium passes through the separation unit, the control unit 151 rotates the feed roller 112 again to start feeding the following medium.

[0105] Next, control unit 151 waits until the trailing edge of the transported medium passes the imaging position of imaging device 119 (step S122). Control unit 151 periodically acquires a fifth medium signal from fifth medium sensor 120, and determines that the trailing edge of the medium has passed the position of fifth medium sensor 120 when the signal value of the fifth medium signal changes from a value indicating the presence of the medium to a value indicating the absence of the medium. Control unit 151 determines that the trailing edge of the medium has passed the imaging position when the trailing edge of the medium has passed the position of fifth medium sensor 120. Note that control unit 151 may also determine that the trailing edge of the medium has passed the imaging position when a predetermined time has elapsed since feeding of the medium began.

[0106] Next, the control unit 151 acquires an input image from the imaging device 119, and outputs the acquired input image by transmitting it to the information processing device via the interface device 134 (step S123).

[0107] 7, time T7 indicates the time when the signal value of the fifth medium signal changes from H to L, i.e., the time when the rear end of the medium passes the imaging position. The control unit 151 acquires an input image from the imaging device 119 when the rear end of the preceding medium passes the imaging position.

[0108] Next, the control unit 151 returns the process to step S105 and repeats the processes from step S105 onwards for the subsequent medium. In this case, in step S107, the control unit 151 controls the third motor 133 to stop the first conveying roller 116 when the leading edge of the subsequent medium passes through the separation unit.

[0109] On the other hand, if there are no media remaining on the mounting table 103 in step S119, the control unit 151 waits until the rear end of the transported medium passes the imaging position of the imaging device 119, similar to the processing in step S122 (step S124).

[0110] Next, the control unit 151 acquires an input image from the imaging device 119, and outputs the acquired input image by transmitting it to the information processing device via the interface device 134 (step S125).

[0111] Next, the control unit 151 waits until the trailing edge of the transported medium passes the discharge section (step S126). The control unit 151 determines that the trailing edge of the medium has passed the discharge section when a certain period of time has passed since the trailing edge of the medium passed the position of the fifth medium sensor 120. The certain period of time is set to the time required for the medium to move from the position of the fifth medium sensor 120 to the downstream end of the discharge section. Note that the control unit 151 may also determine that the trailing edge of the medium has passed the discharge section when a predetermined period of time has passed since feeding of the medium began.

[0112] Next, the control unit 151 controls the second motor 132 and the third motor 133 to stop the separation roller 113, the first conveying roller 116, the first driven roller 117, the second conveying roller 121 and / or the second driven roller 122 (step S127). With the above, the control unit 151 ends the series of steps.

[0113] As described above in detail, the medium conveying device 100 reduces the torque applied to the separation roller 113 while the first conveying roller 116, which is disposed downstream of the separation roller 113, is aligning the leading edge of the medium. This allows the medium conveying device 100 to more effectively align the leading edge of the medium with the first conveying roller 116.

[0114] Therefore, the medium conveying device 100 can suppress the occurrence of skew in the medium, and can reduce the occurrence of medium jams or medium defects in the input image.

[0115] FIG. 9 is a flowchart showing another example of part of the operation of the medium reading process.

[0116] The flowchart shown in Fig. 9 is executed in place of the flowchart shown in Fig. 6. The processes of steps S214, S216 to S217, and S218 to S227 in Fig. 9 are similar to the processes of steps S114, S115 to S116, and S118 to S127 in Fig. 6, so their explanations will be omitted and only step S215 will be explained below.

[0117] After waiting until the leading edge of the fed medium passes the conveying section in step S214, the setting unit 152 sets the torque of the second motor 132 to a first torque value (step S215). That is, similar to the processing in step S117, the setting unit 152 sets the torque applied to the separation roller 113 to the limit value of the torque limiter 113b, and sets the load component applied by the separation roller 113 to the limit value of the torque limiter 113b. Before causing the imaging device 119 to start imaging the medium in step S216, the setting unit 152 sets the torque of the second motor 132 to the first torque value.

[0118] 7, the setting unit 152 returns the torque applied to the separation roller 113 to the limit value of the torque limiter 113b at time T4 when the leading edge of the medium passes the conveying unit, that is, immediately before the medium being conveyed is imaged by the imaging device 119. This resets the torque applied to the separation roller 113 to a torque value suitable for separating the medium, and the medium conveying device 100 can prevent double feeding of media.

[0119] In this way, the setting unit 152 sets the torque applied to the separation roller 113 during the period P3, from time T3 when the leading edge of the medium arrives in front of the conveying unit to time T4 when the leading edge of the medium passes through the conveying unit, to a value smaller than the torque applied to the separation roller 113 during periods other than period P3. That is, the setting unit 152 sets the torque applied to the separation roller 113 from when the first conveying roller 116 starts aligning the leading edge of the medium until the leading edge of the medium reaches the imaging position of the imaging device 119 to a value smaller than the torque applied to the separation roller 113 before the first conveying roller 116 starts aligning the leading edge of the medium. This allows the medium conveying device 100 to successfully align the leading edges of the medium while preventing double feeding of the medium without changing the load component applied to the medium during imaging of the medium. Therefore, the medium conveying device 100 can prevent medium blur (vibration) from occurring in the input image.

[0120] As described above in detail, the medium conveying device 100 is now able to more effectively align the leading edge of the medium using the first conveying roller 116, even when the torque applied to the separation roller 113 is changed before imaging the medium.

[0121] 10 is a diagram showing a schematic configuration of a processing circuit 250 in a medium conveying device according to yet another embodiment. The processing circuit 250 is used in place of the processing circuit 150, and executes medium reading processing and the like in place of the processing circuit 150. The processing circuit 250 includes a control circuit 251, a setting circuit 252, and the like. Note that each of these components may be configured as an independent integrated circuit, microprocessor, firmware, and the like.

[0122] 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 or the interface device 134. The control circuit 251 also receives a first medium signal, a second medium signal, a third medium signal, a fourth medium signal, and a fifth medium signal from the first medium sensor 111, the second medium sensor 114, the third medium sensor 115, the fourth medium sensor 118, and the fifth medium sensor 120, respectively. The control circuit 251 controls the first motor 131, the second motor 132, and the third motor 133 based on the received signals, and also acquires an input image from the imaging device 119 and outputs it to the interface device 134.

[0123] Setting circuit 252 is an example of a setting unit, and has the same function as setting unit 152. Setting circuit 252 receives a third medium signal, a fourth medium signal, and / or a fifth medium signal from third medium sensor 115, fourth medium sensor 118, and / or fifth medium sensor 120, respectively, and sets the torque of second motor 132 based on each received signal.

[0124] As described above in detail, the medium conveying device is now able to more effectively align the leading edge of the medium by the first conveying roller 116, even when using the processing circuit 250.

[0125] Although preferred embodiments have been described above, the embodiments are not limited thereto. For example, the torque limiter 113b may be omitted from the medium conveying device. In this case, in step S103 of FIG. 5, step S117 of FIG. 6, or step S215 of FIG. 9, the first torque value is set to the same value as the limit value of the torque limiter 113b. That is, the first torque value is set to a value such that, when multiple media are conveyed, the separation roller 113 rotates in the direction A5 opposite the medium feeding direction, and when only one medium is conveyed, the separation roller 113 follows the feed roller 112. In this case, the medium conveying device can effectively align the leading edges of the media while suppressing the occurrence of multiple media feeding. Furthermore, by omitting the torque limiter 113b, the medium conveying device can reduce device costs.

[0126] Alternatively, an electromagnetic clutch may be used in place of torque limiter 113b in the medium conveying device. Instead of changing the amount of power (current) supplied to second motor 132, setting unit 152 controls the electromagnetic clutch to change the torque applied to separation roller 113. In this case, second motor 132 does not need to be provided with a torque setting that can be changed. In this case, too, the medium conveying device can successfully align the leading edges of the media while suppressing the occurrence of double feeding of media.

[0127] In the medium conveying device, the first conveying roller 116 and the second conveying roller 121 may be driven by separate motors. [Explanation of symbols]

[0128] 100 medium conveying device, 112 feeding roller, 113 separation roller, 113b torque limiter, 116 first conveying roller, 119 imaging device, 121 second conveying roller, 132 second motor, 152 setting unit

Claims

1. a feeding roller for feeding the medium; a separation roller disposed opposite the feed roller; a conveyance roller disposed downstream of the feed roller in a medium conveyance direction, rotating in a first direction to convey the medium, and stopping or rotating in a second direction opposite to the first direction to align the leading edge of the medium; a motor that generates a driving force for rotating the separation roller and whose torque setting is changeable; a setting unit that sets the torque applied to the separation roller, the setting unit sets the torque of the motor after the conveyance roller starts aligning the leading edge of the medium to a value smaller than the torque of the motor before the conveyance roller starts aligning the leading edge of the medium. A medium transport device characterized by:

2. The device further includes a torque limiter provided between the motor and the separation roller, the torque limiter defining a limit value of the torque applied to the separation roller; 2. The medium transport device according to claim 1, wherein the setting unit sets the torque of the motor to a value greater than the limit value before the transport roller starts to align the leading edge of the medium, and sets the torque of the motor to a value less than the limit value after the transport roller starts to align the leading edge of the medium.

3. a second transport roller disposed downstream of the transport roller in the medium transport direction; 3. The medium transport device of claim 1, wherein the setting unit sets the torque applied to the separation roller from the time the transport roller starts to align the leading edge of the medium until the leading edge of the medium passes the position of the second transport roller to a value smaller than the torque applied to the separation roller before the transport roller starts to align the leading edge of the medium.

4. The image pickup unit is further disposed downstream of the conveyance roller in the medium conveyance direction, 3. The medium conveying device according to claim 1, wherein the setting unit sets the torque applied to the separation roller from the time the conveying roller starts to align the leading edge of the medium until the leading edge of the medium reaches the imaging position of the imaging unit to a value smaller than the torque applied to the separation roller before the conveying roller starts to align the leading edge of the medium.

5. A feed roller feeds the medium. a conveying roller disposed downstream of the feeding roller in the medium conveying direction rotates in a first direction to convey the medium, and stops or rotates in a second direction opposite to the first direction to align the leading edge of the medium; setting a torque applied to a separation roller disposed opposite the feed roller, In the setting, the torque of the motor that generates a driving force for rotating the separation roller after the conveying roller starts to align the leading edge of the medium and whose torque setting is changeable is set to a value smaller than the torque of the motor before the conveying roller starts to align the leading edge of the medium. A medium transport method comprising:

6. A control program for a medium transport device having a feed roller that feeds a medium, a separation roller that is arranged opposite the feed roller, a transport roller that is arranged downstream of the feed roller in a medium transport direction, that rotates in a first direction to transport the medium, and that stops or rotates in a second direction opposite to the first direction to align the leading edge of the medium, and a motor that generates a driving force to rotate the separation roller and has a variable torque setting, causing the medium transport device to set a torque applied to the separation roller; In the setting, the torque of the motor after the conveyance roller starts to align the leading edge of the medium is set to a value smaller than the torque of the motor before the conveyance roller starts to align the leading edge of the medium. A control program comprising:

Images