Medium conveying device, control method and control program

Abstract

To provide a medium conveying device, a control method, and a control program that can better control medium feeding.SOLUTION: A medium conveying device has a mounting table on which media are placed, a feeding roller that separates and sequentially feeds the media placed on the mounting table, a conveying roller that conveys the media fed by the feed roller, a sensor that is disposed between the feeding roller and conveying roller and detects the media, a motor that drives the feeding roller, and a control part which, when feeding the first medium among the media placed on the mounting table, controls the motor to rotate the feeding roller at a constant speed during the separation period from the time when the feeding roller starts feeding the media to the time when the sensor detects the leading edge of the media, and, when feeding the second or subsequent media, controls the motor to rotate the feeding roller at a first speed and then at a second speed higher than the first speed.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present disclosure relates to a medium conveying device, a control method, and a control program, and more particularly to a medium conveying device, a control method, and a control program that separates and sequentially feeds media. [Background technology]

[0002] In media transport devices such as scanners that sequentially feed and capture multiple media while separating them, there is a demand for reducing the time required to feed the media. Meanwhile, media transport devices must temporarily stop feeding the media when there is insufficient free space in the storage device that stores captured images of the media, or when the distance between successively fed media is short. In such cases, media transport devices must be able to appropriately control the stopping and restarting of media feeding.

[0003] A sheet feeding device has been disclosed that controls the speed of the feed roller to be low when starting to feed the subsequent sheet by the feed roller after a post-registration sensor detects the arrival of the trailing edge of the preceding sheet (see Patent Document 1). This sheet feeding device controls the speed of the feed roller to be high when the leading edge of the subsequent sheet passes the nip position between the feed roller and the separation roller. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019 / 130648 Summary of the Invention

[0005] There is a need for better control of media feeding in media transport devices.

[0006] The object of the media transport device, the control method and the control program is to enable better control of the feeding of media.

[0007] A media conveying device according to one aspect of the embodiment includes a mounting table on which media is placed, a feed roller that separates and sequentially feeds the media placed on the mounting table, a transport roller that transports the media fed by the feed roller, a motor that drives the feed roller, a sensor that is positioned downstream of the feed roller in the media transport direction and detects the media, and a control unit that controls the motor to rotate the feed roller at a constant, predetermined speed when feeding the first media among the media placed on the mounting table during the separation period from when the feed roller starts feeding the media to when the sensor detects the leading edge of the media, and controls the motor to rotate the feed roller at a first speed that is higher than the predetermined speed and then at a second speed that is higher than the first speed when feeding the second or subsequent media, and when the leading edge of the media passes the transport roller, the control unit controls the motor to reduce the rotational speed of the feed roller while continuing to rotate the feed roller.

[0008] In addition, a media conveying device according to one aspect of the embodiment includes a mounting table on which media is placed, a feed roller that separates and sequentially feeds the media placed on the mounting table, a motor that drives the feed roller, a sensor that is positioned downstream of the feed roller in the media conveying direction and detects the media, and a control unit that controls the motor to rotate the feed roller at a constant predetermined speed when feeding the first media among the media placed on the mounting table during the separation period from when the feed roller starts feeding the media to when the sensor detects the leading edge of the media, and controls the motor to rotate the feed roller at a first speed that is higher than the predetermined speed and then at a second speed that is higher than the first speed when feeding the second or subsequent media, and the control unit sets the second speed when the size of the preceding media is equal to or smaller than a size threshold to a speed lower than the second speed when the size of the preceding media is larger than the size threshold.

[0009] Also, a media transport device according to one aspect of the embodiment is a media transport device having a normal mode and a thin paper transport mode, and includes a mounting table on which media are placed, a feed roller that separates and sequentially feeds the media placed on the mounting table, a transport roller that transports the media fed by the feed roller, a motor that drives the feed roller, a sensor that is disposed downstream of the feed roller in the media transport direction and detects the media, and a mechanism that rotates the feed roller at a constant predetermined speed when feeding the first medium of the media placed on the mounting table during a separation period from when the feed roller starts feeding the media until the sensor detects the leading edge of the media. and a control unit that controls the motor so that, when feeding the second or subsequent medium, the feed roller is rotated at a first speed higher than the predetermined speed and then at a second speed higher than the first speed, and the control unit sets the rotation speed of the feed roller and the rotation speed of the conveying roller so that the ratio of the surface movement speed of the feed roller to the surface movement speed of the conveying roller in the normal mode is smaller than the ratio of the surface movement speed of the feed roller to the surface movement speed of the conveying roller in the thin paper conveying mode, and the surface movement speed of the feed roller in the normal mode is greater than the surface movement speed of the feed roller in the thin paper conveying mode. In addition, a control program according to one aspect of the embodiment is a control program for a media conveying device having a mounting table on which media is placed, a feed roller that separates and sequentially feeds the media placed on the mounting table, a motor that drives the feed roller, and a sensor that is positioned downstream of the roller in the media conveying direction and detects the media, and during the separation period from when the feed roller starts feeding the media to when the sensor detects the leading edge of the media, when feeding the first media placed on the mounting table, controls the motor to rotate the feed roller at a constant, predetermined speed, and when feeding the second or subsequent media, controls the motor to rotate the feed roller at a first speed that is higher than the predetermined speed and then at a second speed that is higher than the first speed.

[0010] According to the present embodiment, the medium transport device, the control method, and the control program are able to better control the feeding of the medium.

[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] FIG. 2 is a schematic diagram for explaining a driving source. [Figure 4] FIG. 10 is a schematic diagram for explaining a third medium sensor 116 and the like. [Figure 5] FIG. 10 is a schematic diagram for explaining a third medium sensor 116 and the like. [Figure 6] 1 is a block diagram showing a schematic configuration of a medium conveying device 100. FIG. [Figure 7] FIG. 2 is a diagram showing a schematic configuration of a storage device 140 and a processing circuit 150. [Figure 8] 10 is a flowchart illustrating an example of the operation of a medium reading process. [Figure 9] 10 is a flowchart illustrating an example of the operation of a medium reading process. [Figure 10] 10 is a graph for explaining a change in the speed of a roller. [Figure 11] 10 is a graph for explaining a change in the speed of a roller. [Figure 12] 10 is a graph for explaining a change in the speed of a roller. [Figure 13] (a) and (b) are schematic diagrams for explaining the technical significance. [Figure 14] FIG. 10 is a schematic diagram for explaining the technical significance. [Figure 15] FIG. 10 is a schematic diagram for explaining another driving source. [Figure 16] 10 is a flowchart illustrating an example of a portion of the operation of another medium reading process. [Figure 17] 10 is a graph for explaining a change in the speed of a roller. [Figure 18] 10 is a flowchart illustrating an example of a portion of the operation of yet another medium reading process. [Figure 19] 10 is a graph for explaining a change in the speed of a roller. [Figure 20] 10 is a flowchart illustrating an example of the operation of yet another medium reading process. [Figure 21] 10 is a flowchart illustrating an example of the operation of yet another medium reading process. [Figure 22] 10 is a graph for explaining a change in the speed of a roller. [Figure 23] FIG. 10 is a schematic diagram for explaining yet another driving source. [Figure 24] 10 is a flowchart illustrating an example of the operation of yet another medium reading process. [Figure 25] 10 is a flowchart illustrating an example of the operation of yet another medium reading process. [Figure 26] 10 is a graph for explaining a change in the speed of a roller. [Figure 27] FIG. 10 is a schematic diagram for explaining yet another driving source. [Figure 28] FIG. 10 is a schematic diagram for explaining yet another driving source. [Figure 29] 10 is a flowchart illustrating an example of a portion of the operation of yet another medium reading process. [Figure 30] 10 is a graph for explaining a change in the speed of a roller. [Figure 31] FIG. 10 is a schematic diagram for explaining yet another driving source. [Figure 32] 10 is a flowchart illustrating an example of a portion of the operation of yet another medium reading process. [Figure 33] 10 is a graph for explaining a change in the speed of a roller. [Figure 34]10 is a flowchart illustrating an example of the operation of yet another medium reading process. [Figure 35] 10 is a flowchart illustrating an example of the operation of yet another medium reading process. [Figure 36] 10 is a graph for explaining a change in the speed of a roller. [Figure 37] 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 control 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 of the medium. The medium may be paper, cardboard, a card, a booklet, a passport, or the like. The medium conveying device 100 may also be a facsimile machine, a copier, a multifunction peripheral (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, 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 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 brake roller 113, a second media sensor 114, an ultrasonic sensor 115, a third media sensor 116, a fourth media sensor 117, a fifth media sensor 118, a transport roller 119, a first opposing roller 120, a sixth media sensor 121, an imaging device 122, a discharge roller 123, and a second opposing roller 124, etc.

[0021] The number of each of the feed roller 112, brake roller 113, transport roller 119, first opposing roller 120, discharge roller 123, and / or second opposing roller 124 is not limited to one, and may be more than one. In this case, the multiple feed rollers 112, brake roller 113, transport roller 119, first opposing roller 120, discharge roller 123, and / or second opposing roller 124 are arranged at intervals in the width direction perpendicular to the medium transport direction A1.

[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. In Figure 2, arrow A1 indicates the medium transport direction. Hereinafter, "upstream" refers to the upstream side of the medium transport direction A1, and "downstream" refers to the downstream side of the medium transport direction A1.

[0023] The first medium sensor 111 is disposed upstream of the feed roller 112 and the brake 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, and separates and feeds the media placed on the mounting table 103 in order from the bottom up. The brake roller 113 is provided in the upper housing 102, and is disposed opposite the feed roller 112, rotating in the opposite direction to the media feeding direction. Alternatively, the feed roller 112 may be provided in the upper housing 102 and the brake roller 113 in the lower housing 101, and the feed roller 112 may feed the media placed on the mounting table 103 in order from the top up.

[0025] The second media sensor 114 is an example of a second sensor and is located downstream of the feed roller 112 and upstream of the transport roller 119 to detect media transported to that position. In particular, the second media sensor 114 is located between the feed roller 112 and the fifth media sensor 118 in the media transport direction A1, near the nip region between the feed roller 112 and the brake roller 113. 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. On the other hand, 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 medium sensor 114 generates and outputs a second medium signal whose signal value changes depending on whether a medium is present or not at the position of the second medium sensor 114, based on the intensity of light received by the light receiver.

[0026] The ultrasonic sensor 115 is located downstream of the feed roller 112 and upstream of the conveying roller 119. The ultrasonic sensor 115 includes an ultrasonic transmitter 115a and an ultrasonic receiver 115b. The ultrasonic transmitter 115a and the ultrasonic receiver 115b are located near the medium conveying path, facing each other across the conveying path. The ultrasonic transmitter 115a emits ultrasonic waves. The ultrasonic receiver 115b receives the ultrasonic waves emitted by the ultrasonic transmitter 115a and transmitted through the medium, and generates and outputs an ultrasonic signal, which is an electrical signal corresponding to the received ultrasonic waves. When multiple media are conveyed in an overlapping state, the ultrasonic waves transmitted through the media are attenuated by the air gap between the overlapping media. Therefore, the medium conveying device 100 can detect double feeding of media based on the ultrasonic signal. Furthermore, the ultrasonic waves transmitted through the media are also attenuated by the media themselves, and the thicker the medium, the greater the attenuation. Therefore, the medium conveying device 100 can detect the thickness of the conveyed media based on the ultrasonic signal.

[0027] The fifth media sensor 118 is an example of a sensor and is located downstream of the feed roller 112 and upstream of the transport roller 119 to detect media transported to that position. That is, the fifth media sensor 118 is located between the feed roller 112 and the transport roller 119. The fifth media sensor 118 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 the 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. The fifth media sensor 118 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 medium is present or absent at the position of the fifth media sensor 118.

[0028] The transport roller 119 and the first opposing roller 120 are disposed downstream of the feed roller 112 and facing each other, and transport the medium fed by the feed roller 112 and the brake roller 113 to the imaging device 122. The transport roller 119 is provided in the upper housing 102, and the first opposing roller 120 is provided in the lower housing 101, below the transport roller 119.

[0029] The sixth media sensor 121 is disposed downstream of the transport rollers 119 and upstream of the imaging device 122, and detects media transported to that position. The sixth media sensor 121 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. 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 sixth media sensor 121 generates and outputs a sixth 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 sixth media sensor 121.

[0030] The imaging device 122 is an example of an imaging unit, and is disposed downstream of the transport rollers 119 to capture an image of the medium transported by the transport rollers 119. The imaging device 122 includes a first imaging device 122a and a second imaging device 122b disposed opposite each other across the medium transport path. The first imaging device 122a 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. The first imaging device 122a 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 122a 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.

[0031] Similarly, the second imaging device 122b 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 122b 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 122b 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.

[0032] Note that the medium conveying device 100 may have only one of the first and second imaging devices 122a and 122b, 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.

[0033] The discharge roller 123 and the second opposing roller 124 are disposed downstream of the imaging device 122 and facing each other, and discharge the medium that has been transported by the transport roller 119 and the first opposing roller 120 and imaged by the imaging device 122 onto the discharge tray 104. The discharge roller 123 is provided in the upper housing 102, and the second opposing roller 124 is provided in the lower housing 101, below the discharge roller 123.

[0034] The media placed on the mounting table 103 is transported between the lower guide 101a and the upper guide 102a in the media transport direction A1 by the rotation of the feed roller 112 in the direction of arrow A2 in Figure 2, i.e., the media feed direction. When transporting the media, the brake roller 113 rotates in the direction of arrow A3, i.e., the opposite direction to the media feed direction. 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 restricts the transport of media other than the separated media (preventing double feeding).

[0035] The medium is guided by lower guide 101a and upper guide 102a and fed between conveying roller 119 and first opposing roller 120. The medium is fed between first imaging device 122a and second imaging device 122b as conveying roller 119 and first opposing roller 120 rotate in the directions of arrows A4 and A5, respectively. The medium read by imaging device 122 is discharged onto discharge tray 104 as discharge roller 123 and second opposing roller 124 rotate in the directions of arrows A6 and A7, respectively.

[0036] FIG. 3 is a schematic diagram for explaining the drive sources of the feed roller 112, the brake roller 113, the transport roller 119, the first opposing roller 120, the discharge roller 123 and / or the second opposing roller .

[0037] As shown in FIG. 3, the medium conveying device 100 has a first motor 131 and a second motor 132 as drive sources for the rollers.

[0038] First motor 131 is an example of a motor, and is provided in lower housing 101. First motor 131 is connected to feed roller 112 via first transmission mechanism 131a to drive feed roller 112. First motor 131 generates a driving force for driving feed roller 112 in response to a control signal from the processing circuit. First transmission mechanism 131a includes one or more pulleys, belts, gears, etc., provided between first motor 131 and shaft 112a of feed roller 112, and transmits the driving force generated by first motor 131 to feed roller 112. In this way, first motor 131 rotates feed roller 112 to feed the medium.

[0039] The second motor 132 is provided in the upper housing 102 separately from the first motor 131, and is connected to the conveying rollers 119, the discharge rollers 123, and the brake roller 113 via a second transmission mechanism 132a to drive the conveying rollers 119, the discharge rollers 123, and the brake roller 113. The second motor 132 generates driving forces for driving the conveying rollers 119, the discharge rollers 123, and the brake roller 113 in response to control signals from the processing circuit. The second transmission mechanism 132a includes one or more pulleys, belts, gears, etc. provided between the second motor 132 and the shaft 119a of the conveying roller 119, the shaft 123a of the discharge roller 123, and the shaft 113a of the brake roller 113. In particular, one or more gears are provided between the shaft 119a of the conveyance roller 119 and / or the shaft 123a of the discharge roller 123 and the shaft 113a of the brake roller 113 to vary the rotation direction and rotation speed of each roller. The second transmission mechanism 132a transmits the driving force generated by the second motor 132 to the conveyance roller 119, the discharge roller 123, and the brake roller 113. As a result, the second motor 132 rotates the conveyance roller 119, the discharge roller 123, and the brake roller 113, causing the conveyance roller 119, the discharge roller 123, and the brake roller 113 to feed, convey, and discharge the medium. The second motor 132 is an example of a drive source for the brake roller 113.

[0040] The first opposing roller 120 is a driven roller that rotates following the conveyance roller 119, and the second opposing roller 124 is a driven roller that rotates following the discharge roller 123. The first opposing roller 120 and / or the second opposing roller 124 may be driven by a driving force from a second motor 132. In this case, one or more gears are further provided between the shaft 119a of the conveyance roller 119 and the shaft 120a of the first opposing roller 120, and / or between the shaft 123a of the discharge roller 123 and the shaft 124a of the second opposing roller 124. The second transmission mechanism 132a further transmits the driving force generated by the second motor 132 to the first opposing roller 120 and / or the second opposing roller 124.

[0041] 4 and 5 are schematic diagrams for explaining the third medium sensor 116 and the fourth medium sensor 117. Fig. 4 is a schematic diagram of the lower guide 101a of the lower housing 101 as seen from above, and Fig. 5 is a schematic diagram of the upper guide 102a of the upper housing 102 as seen from below.

[0042] 4 and 5, the third medium sensor 116 and the fourth medium sensor 117 are disposed downstream of the feed roller 112 and upstream of the transport roller 119, and detect the medium transported to that position. In particular, the third medium sensor 116 and the fourth medium sensor 117 are disposed between the second medium sensor 114 and the fifth medium sensor 118 in the medium transport direction A1. The third medium sensor 116 and the fourth medium sensor 117 may be disposed in approximately the same position as the fifth medium sensor 118 in the medium transport direction A1. The third medium sensor 116 and the fourth medium sensor 117 are also disposed side by side with a gap between them in the width direction A8, which is perpendicular to the medium transport direction.

[0043] The third medium sensor 116 includes a light emitter and a light receiver provided on one side of the medium transport path, and a light guide tube provided opposite the light emitter and light receiver across the medium transport path. The light emitter is an LED or the like and emits light toward the medium transport path. 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 third medium sensor 116 generates and outputs a third medium signal based on the intensity of the light received by the light receiver, the signal value of which changes depending on whether a medium is present or not at the position of the third medium sensor 116.

[0044] The fourth medium sensor 117 includes a light emitter and a light receiver provided on one side of the medium transport path, and a light guide tube provided opposite the light emitter and light receiver across the medium transport path. The light emitter is an LED or the like and emits light toward the medium transport path. 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 117 generates and outputs a fourth medium signal based on the intensity of the light received by the light receiver. The signal value changes depending on whether a medium is present or not at the position of the fourth medium sensor 117.

[0045] Note that a reflective member such as a mirror may be used instead of a light guide tube in second medium sensor 114, third medium sensor 116, fourth medium sensor 117, fifth medium sensor 118, and / or sixth medium sensor 121. Also, in second medium sensor 114, third medium sensor 116, fourth medium sensor 117, fifth medium sensor 118, and / or sixth medium sensor 121, the light emitter and light receiver may be disposed opposite each other across the medium transport path. Also, second medium sensor 114, third medium sensor 116, fourth medium sensor 117, fifth medium sensor 118, and / or sixth medium sensor 121 may detect the presence of a medium using a contact detection sensor or the like that passes a predetermined current when the medium is in contact or not in contact.

[0046] 4, the medium conveying device 100 also has a first electromagnetic clutch 133. The first electromagnetic clutch 133 is an example of a cutoff mechanism, and is provided on the shaft 112a of the feed roller 112, i.e., on the driving force transmission path from the first motor 131 to the feed roller 112. The first electromagnetic clutch 133 is provided so as to be able to cut off the driving force from the first motor 131 to the feed roller 112 in response to a control signal from the processing circuit.

[0047] 5, the medium conveying device 100 also has a second electromagnetic clutch 134. The second electromagnetic clutch 134 is an example of an electromagnetic clutch, and is provided on the shaft 113a of the brake roller 113, i.e., on a driving force transmission path from the second motor 132, which is the driving source of the brake roller 113, to the brake roller 113. The second electromagnetic clutch 134 is provided so that the magnitude of the torque applied to the brake roller 113 can be changed by a control signal from a processing circuit.

[0048] FIG. 6 is a block diagram showing a schematic configuration of the medium conveying device 100. As shown in FIG.

[0049] In addition to the components described above, the medium transport device 100 further includes an interface device 135, a storage device 140, a processing circuit 150, and the like.

[0050] The interface device 135 has an interface circuit conforming to a serial bus such as USB, and is electrically connected to an information processing device (not shown) (for example, a personal computer, a personal digital assistant, etc.) to transmit and receive input images and various information. Instead of the interface device 135, 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.

[0051] 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.

[0052] 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.

[0053] 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 ultrasonic sensor 115, the third medium sensor 116, the fourth medium sensor 117, the fifth medium sensor 118, the sixth medium sensor 121, the imaging device 122, the first motor 131, the second motor 132, the first electromagnetic clutch 133, the second electromagnetic clutch 134, the interface device 135, and the storage device 140, and controls each of these components. Based on the medium signals received from the sensors, the processing circuit 150 controls the driving of the first motor 131, controls the imaging of the imaging device 122, and so on, acquires an input image from the imaging device 122, and transmits the image to the information processing device via the interface device 135.

[0054] FIG. 7 is a diagram showing a schematic configuration of the storage device 140 and the processing circuit 150. As shown in FIG.

[0055] 7, the storage device 140 stores a control program 141, a determination program 142, and the like. Each of these programs is a functional module implemented by software running on a processor. The processing circuit 150 reads each program stored in the storage device 140 and operates in accordance with the read program. As a result, the processing circuit 150 functions as a control unit 151 and a determination unit 152.

[0056] 8 and 9 are flowcharts showing an example of the operation of the medium reading process of the medium conveying device 100. FIG.

[0057] 8 and 9, 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.

[0058] 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 135 (step S101).

[0059] 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.

[0060] On the other hand, when a medium is placed on the placement table 103, the control unit 151 sets the surface movement speeds of the feed roller 112, the brake roller 113, the transport roller 119, the first opposing roller 120, the discharge roller 123, and / or the second opposing roller 124 (step S103). The surface movement speed is the speed at which the surface of each roller that comes into contact with the medium moves. In other words, the surface movement speeds of the feed roller 112, the transport roller 119, the first opposing roller 120, the discharge roller 123, and / or the second opposing roller 124 are the speed at which the medium is transported by the feed roller 112, the transport roller 119, and the discharge roller 123. The surface movement speed of the brake roller 113 is the speed at which the surface of the brake roller 113 that comes into contact with the medium moves in the direction opposite to the medium feeding direction. Hereinafter, the surface movement speed of each roller may be simply referred to as "speed."

[0061] The medium conveying device 100 has three conveying modes for conveying a medium: a high-speed mode, a medium-speed mode, and a low-speed mode. The conveying mode is set by the user using the operation device 105 or the information processing device before the medium reading process is executed.

[0062] 10 to 12 are graphs for explaining the speed changes of the feed roller 112, the brake roller 113, the conveying roller 119, the first opposing roller 120, the discharge roller 123, and the second opposing roller 124. Fig. 10 shows the speed changes of each roller in high-speed mode, Fig. 11 shows the speed changes of each roller in medium-speed mode, and Fig. 12 shows the speed changes of each roller in low-speed mode.

[0063] 10 to 12, graphs G11, G21, and G31 show the speed change of the feed roller 112, graphs G12, G22, and G32 show the speed change of the brake roller 113, and graphs G13, G23, and G33 show the speed change of the conveying roller 119. The speeds of the first opposing roller 120, discharge roller 123, and second opposing roller 124 change in the same way as the speed of the conveying roller 119, so below we will explain the speed change of the conveying roller 119 as a representative. The horizontal axis of each of the graphs G11 to G13, G21 to G23, and G31 to G33 represents time, and the vertical axis represents speed.

[0064] Meanwhile, graph G14 shows the change in the signal value of fifth medium sensor 118, and graph G15 shows the change in the signal value of sixth medium sensor 121. The horizontal axis of each of graphs G14 and G15 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.

[0065] 10 to 12, time T1 indicates the start of medium feeding. As shown in FIGS. 10 to 12, when the transport mode is set to any of the high-speed mode, medium-speed mode, and low-speed mode, the control unit 151 sets the speed of the feed roller 112 to an initial speed V1 at the start of medium feeding. Furthermore, when the transport mode is set to the high-speed mode, the control unit 151 sets the speed of the brake roller 113 to an initial speed U1 and sets the speed of the transport roller 119 to an initial speed W1. The initial speed U1 of the brake roller 113 is set to a speed higher than half the initial speed V1 of the feed roller 112. Furthermore, the initial speed U1 of the brake roller 113 may be set to a speed lower than the initial speed V1 of the feed roller 112.

[0066] On the other hand, when the conveying mode is set to the medium speed mode, the control unit 151 sets the speed of the brake roller 113 to a final speed U3b, and sets the speed of the conveying roller 119 to a final speed W3b. The final speed U3b of the brake roller 113 is set to a speed lower (slower) than the final speed U3a of the brake roller 113 in the high speed mode, which will be described later. The final speed W3b of the conveying roller 119 is set to a speed lower than the final speed W3a of the conveying roller 119 in the high speed mode, which will be described later. Furthermore, when the conveying mode is set to the low speed mode, the control unit 151 sets the speed of the brake roller 113 to a final speed U3c, and sets the speed of the conveying roller 119 to a final speed W3c. The final speed U3c of the brake roller 113 is set to a speed lower than the final speed U3b of the brake roller 113 in the medium speed mode. The final speed W3c of the conveying roller 119 is set to a speed lower than the final speed W3c of the conveying roller 119 in the medium speed mode.

[0067] Next, the control unit 151 drives the first motor 131 and the second motor 132. As a result, the control unit 151 rotates the feed roller 112, the brake roller 113, the transport roller 119, the first opposing roller 120, the discharge roller 123, and / or the second opposing roller 124 to feed and transport the medium (step S104).

[0068] Control unit 151 controls first motor 131 and second motor 132 so as to rotate each roller at a set speed. As shown in FIGS. 10 to 12, each roller rotates at its set speed after a predetermined slew-up period has elapsed since the start of driving each motor at time T1. Similarly, if control unit 151 subsequently increases the speed of each roller, each roller rotates at its set speed after a predetermined slew-up period has elapsed since the start of driving each motor. Similarly, if control unit 151 reduces the speed of each roller, each roller rotates at its set speed after a predetermined slew-down period has elapsed since the start of driving each motor.

[0069] Next, control unit 151 waits until the leading edge of the transported medium passes the position of fifth medium sensor 118 (step S105). Control unit 151 periodically acquires a fifth medium signal from fifth medium sensor 118, and determines that the leading edge of the medium has passed the position of fifth medium sensor 118 when the signal value of the fifth medium signal changes from a value indicating that no medium is present to a value indicating that a medium is present.

[0070] Next, the control unit 151 changes the speed of the feed roller 112 and the brake roller 113 (step S106).

[0071] 10 to 12, time T2 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 the position of fifth medium sensor 118. As shown in FIGS. 10 to 12, the speed of feed roller 112 that is changed when the leading edge of the medium passes the position of fifth medium sensor 118 differs depending on the transport mode.

[0072] When the conveying mode is set to the high-speed mode, the control unit 151 changes the speed of the feed roller 112 to a final speed V3a. The final speed V3a of the feed roller 112 is set to a speed that is higher than the initial speed V1 of the feed roller 112 and equal to or lower than a final speed W3a of the conveying roller 119, which will be described later. The final speed V3a of the feed roller 112 may be set to the same speed as the final speed W3a of the conveying roller 119. When the conveying mode is set to the medium-speed mode, the control unit 151 changes the speed of the feed roller 112 to a final speed V3b. The final speed V3b of the feed roller 112 in the medium-speed mode is set to a speed that is higher than the initial speed V1 and lower than the final speed V3a in the high-speed mode. When the conveying mode is set to the low-speed mode, the control unit 151 changes the speed of the feed roller 112 to a final speed V3c. The final speed V3c of the feed roller 112 in the low speed mode is set to a speed higher than the initial speed V1 and lower than the final speed V3b in the medium speed mode.

[0073] Furthermore, when the conveying mode is set to the high-speed mode, the control unit 151 changes the speed of the brake roller 113 to a final speed U3a and changes the speed of the conveying roller 119 to a final speed W3a. The final speed U3a of the brake roller 113 is set to a speed higher than the initial speed U1 of the brake roller 113. The final speed W3a of the conveying roller 119 is set to a speed higher than the initial speed W1 of the conveying roller 119. On the other hand, when the conveying mode is set to the medium-speed mode, the speeds of the brake roller 113 and the conveying roller 119 are already set to the final speeds U3b and W3b, so the control unit 151 does not change the speeds of the brake roller 113 and the conveying roller 119. Similarly, when the conveying mode is set to the low-speed mode, the speeds of the brake roller 113 and the conveying roller 119 are already set to the final speeds U3c and W3c, so the control unit 151 does not change the speeds of the brake roller 113 and the conveying roller 119.

[0074] Next, control unit 151 waits until the leading edge of the transported medium passes the position of transport rollers 119 (step S107). Control unit 151 periodically acquires a sixth medium signal from sixth medium sensor 121, and when the signal value of the sixth medium signal changes from a value indicating that the medium is not present to a value indicating that the medium is present, control unit 151 determines that the leading edge of the medium has passed the position of sixth medium sensor 121. When the leading edge of the medium passes the position of sixth medium sensor 121, control unit 151 determines that the leading edge of the medium has passed the position of transport rollers 119.

[0075] Next, the control unit 151 controls the first motor 131 to stop the feeding roller 112 (step S108).

[0076] 10 to 12, time T3 indicates the time when the signal value of the sixth medium signal changes from L to H, i.e., the time when the leading edge of the medium passes the position of sixth medium sensor 121. As shown in FIGS. 10 to 12, after the leading edge of the medium passes the position of sixth medium sensor 121, control unit 151 stops feed roller 112 (changes the speed to 0). As a result, the medium is subsequently transported by transport roller 119, and feed roller 112 rotates along with the transported medium. By stopping feed roller 112, control unit 151 can prevent the medium from being pushed by feed roller 112 and bending between feed roller 112 and transport roller 119, which could cause a medium jam.

[0077] Next, the control unit 151 causes the imaging device 122 to start imaging the medium (step S109).

[0078] Next, control unit 151 waits until the trailing edge of the transported medium passes the position of fifth medium sensor 118 (step S110). Control unit 151 periodically acquires a fifth medium signal from fifth medium sensor 118, and determines that the trailing edge of the medium has passed the position of fifth medium sensor 118 when the signal value of the fifth medium signal changes from a value indicating the presence of a medium to a value indicating the absence of a medium.

[0079] 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 S111).

[0080] If any media remain on the mounting table 103, the control unit 151 sets the speed of the feeding roller 112 for feeding the subsequent media (step S112).

[0081] 10 to 12, time T4 indicates the time when the signal value of the fifth medium signal changes from H to L, i.e., the time when the trailing edge of the medium passes the position of the fifth medium sensor 118. As shown in FIGS. 10 to 12, when the trailing edge of the medium passes the position of the fifth medium sensor 118, the speed of the feed roller 112 set to feed the subsequent medium varies depending on the transport mode. When the transport mode is set to high-speed mode or medium-speed mode, the control unit 151 sets the speed of the feed roller 112 to a first intermediate speed V2a. The first intermediate speed V2a is an example of a first speed, and is set to a speed higher than the initial speed V1 and lower than the final speeds V3a and V3b. The first speed is the first speed of the feed roller 112 when feeding the second or subsequent medium. Note that the first intermediate speed V2a may be set to approximately the same speed as the final speed V3c. On the other hand, when the transport mode is set to the low-speed mode, the control unit 151 sets the speed of the feed roller 112 to the final speed V3c.

[0082] Next, the control unit 151 drives the first motor 131 to rotate the feed roller 112 and feed and transport the subsequent medium (step S113). The control unit 151 controls the first motor 131 to rotate the feed roller 112 at a set speed.

[0083] Next, control unit 151 waits until the leading edge of the following medium passes the position of second medium sensor 114 (step S114). Control unit 151 periodically acquires a second medium signal from second medium sensor 114, and determines that the leading edge of the medium has passed the position of second medium sensor 114 when the signal value of the second medium signal changes from a value indicating that no medium is present to a value indicating that a medium is present.

[0084] Next, the control unit 151 changes the speed of the feeding roller 112 (step S115).

[0085] As shown in FIGS. 10 to 12, the speed of the feed roller 112, which is changed when the leading edge of the following medium passes the position of the second medium sensor 114, varies depending on the transport mode. When the transport mode is set to the high-speed mode, the control unit 151 changes the speed of the feed roller 112 to a second intermediate speed V2b. The second intermediate speed V2b is an example of the second speed, and is set to a speed higher than the first intermediate speed V2a and lower than the final speed V3a. The second speed is the second-stage speed of the feed roller 112 when feeding the second or subsequent medium. Note that the second intermediate speed V2b may be set to approximately the same value as the final speed V3b. On the other hand, when the transport mode is set to the medium-speed mode, the control unit 151 changes the speed of the feed roller 112 to the final speed V3b. When the transport mode is set to the low-speed mode, the control unit 151 does not change the speed of the feed roller 112.

[0086] Next, control unit 151 waits until the trailing edge of the preceding medium passes the imaging position of imaging device 122 (step S116). Control unit 151 periodically acquires a sixth medium signal from sixth medium sensor 121, and determines that the trailing edge of the preceding medium has passed the position of sixth medium sensor 121 when the signal value of the sixth medium signal changes from a value indicating the presence of a medium to a value indicating the absence of a medium. Control unit 151 determines that the trailing edge of the preceding medium has passed the imaging position when a first predetermined time has elapsed since the trailing edge of the preceding medium passed the position of sixth medium sensor 121. The first predetermined time is set to a value obtained by adding a margin to the time required for the medium to move from the position of sixth medium sensor 121 to the imaging position.

[0087] Next, the control unit 151 acquires an input image from the imaging device 122, and stores the acquired input image in the storage device 140. The control unit 151 outputs the input image stored in the storage device 140 by transmitting it to the information processing device via the interface device 135, and deletes it from the storage device 140 (step S117).

[0088] Next, similar to the process in step S105, the control unit 151 waits until the leading edge of the succeeding medium passes the position of the fifth medium sensor 118 (step S118).

[0089] Next, the control unit 151 changes the speed of the feeding roller 112 (step S119).

[0090] 10 to 12, 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 following medium passes the position of fifth medium sensor 118. As shown in FIGS. 10 to 12, when the transport mode is set to high-speed mode, control unit 151 changes the speed of feed roller 112 to final speed V3a when the leading edge of the following medium passes the position of fifth medium sensor 118. On the other hand, when the transport mode is set to medium-speed mode or low-speed mode, control unit 151 does not change the speed of feed roller 112.

[0091] Next, the control unit 151 returns the process to step S107 and repeats the processes from step S107 onwards for the subsequent medium. In this case, in step S107, the control unit 151 waits until the leading edge of the subsequent medium passes the position of the conveying roller 119 (time T6 in FIG. 10), and in step S108, controls the first motor 131 to stop the feeding roller 112.

[0092] On the other hand, if there are no media remaining on the mounting table 103 in step S111, the control unit 151 waits until the rear end of the transported medium passes the imaging position of the imaging device 122 (step S120), similar to the processing in step S116.

[0093] Next, the control unit 151 acquires an input image from the imaging device 122, and outputs the acquired input image by transmitting it to the information processing device via the interface device 135 (step S121).

[0094] Next, the control unit 151 waits until the trailing edge of the transported medium passes the position of the discharge rollers 123 (step S122). The control unit 151 determines that the trailing edge of the medium has passed the position of the discharge rollers 123 when a second predetermined time has elapsed since the trailing edge of the medium passed the position of the sixth medium sensor 121. The second predetermined time is set to a value obtained by adding a margin to the time required for the medium to move from the position of the sixth medium sensor 121 to the position of the discharge rollers 123.

[0095] Next, the control unit 151 controls the second motor 132 to stop the brake roller 113, the conveying roller 119, the first opposing roller 120, the discharge roller 123 and / or the second opposing roller 124 (step S123), and ends the series of steps.

[0096] Note that in step S117, control unit 151 may execute the processes from step S118 onwards even if transmission of the input image has not been completed. In this case, in step S118, control unit 151 may temporarily stop feeding of the subsequent medium if the free space in storage device 140 is less than a predetermined amount when the leading edge of the subsequent medium passes the position of fifth medium sensor 118. Control unit 151 controls first motor 131 to stop feed roller 112 until the free space in storage device 140 becomes equal to or greater than the predetermined amount. This enables medium conveying device 100 to efficiently convey media while reliably transmitting the input image.

[0097] Furthermore, in step S118, if the distance between the trailing edge of the preceding medium and the leading edge of the following medium is short when the leading edge of the following medium passes the position of the fifth medium sensor 118, the control unit 151 may temporarily stop feeding of the following medium. For example, the control unit 151 detects the time from when the trailing edge of the preceding medium passes the position of the fifth medium sensor 118 or the sixth medium sensor 121 until the leading edge of the following medium passes the position of the fifth medium sensor 118. If the measured time is less than a third predetermined time, the control unit 151 controls the first motor 131 to stop the feed roller 112 until the third predetermined time has elapsed since the trailing edge of the preceding medium passed the position of the fifth medium sensor 118 or the sixth medium sensor 121. This enables the medium conveying device 100 to convey media efficiently while suppressing the occurrence of medium jams.

[0098] 13(a) and 13(b) are schematic diagrams for explaining the technical significance of feeding a medium in accordance with the medium reading process shown in FIGS. 8 and 9. FIG.

[0099] 13(a) and (b) are schematic side views of the feed roller 112 and the brake roller 113. Fig. 13(a) shows a state in which the first medium M1 is being fed from a state in which the medium group M is placed on the mounting table 103, and Fig. 13(b) shows a state in which the second or subsequent medium M2 is being fed from a state in which the medium group M is placed on the mounting table 103.

[0100] As shown in FIG. 13(a), when a certain number of media M are placed on the placement table 103, the leading edges of the media M are usually aligned by the user or by an alignment member (not shown). Therefore, the leading edge of the first medium M1, which is placed at the bottom, does not reach the nip area between the feed roller 112 and the brake roller 113. In this case, the weight of the media placed above the first medium M1 increases the frictional force between the media. Due to this frictional force, the media placed above the first medium M1 attempt to move downstream along with the first medium M1 being fed, and are pressed against the brake roller 113. If the speed of the feed roller 112 is too high at this time, the brake roller 113 may be lifted upward by the media placed above the first medium M1, causing the media to enter between the feed roller 112 and the brake roller 113, potentially resulting in double feeding of media.

[0101] Also, if the speed of the feed roller 112 at this time is too high, the leading edge of the first medium M1 may lift up before reaching the nip area between the feed roller 112 and the brake roller 113, which may cause the medium M1 to buckle and result in a medium jam.

[0102] As shown in steps S103 to S105 of FIG. 8, when feeding the first medium among the media placed on the mounting table 103, the control unit 151 controls the first motor 131 to rotate the feed roller 112 at a constant speed during the separation period from when the feed roller 112 starts feeding the medium until the fifth medium sensor 118 detects the leading edge of the medium. The separation period when feeding the first medium is the period from time T1 to time T2 in FIGS. 10 to 12. In particular, when feeding the first medium, the control unit 151 controls the first motor 131 to rotate the feed roller 112 at an initial speed V1 that is lower than the first intermediate speed V2a when feeding the second or subsequent media. By reducing the speed of the feed roller 112 during the separation period of the first medium, the control unit 151 can prevent the occurrence of double feeding or jamming of media.

[0103] On the other hand, as shown in FIG. 13(b), when the first medium M1 is fed, the second and subsequent media M2 are separated by the brake roller 113, and the leading edge of each medium M2 abuts against the brake roller 113. As with the case when the first medium M1 is fed, if the speed of the feed roller 112 is too high, there is a possibility that a double feed or jam of media may occur when the second and subsequent media M2 are fed. However, compared to the case when the first medium M1 is fed, there is a lower possibility that a double feed or jam may occur when the second and subsequent media M2 are fed. On the other hand, if the feed speed during the separation period of the second and subsequent media M2 is too low, it will take a long time to complete the transport of all the media. However, if the speed of the stopped feed roller 112 is suddenly increased when the second and subsequent media M2 are fed, there is a possibility that the first motor 131 will lose synchronization.

[0104] As shown in steps S112 to S115 and S118 of FIG. 9 , when the transport mode is set to the high-speed mode, the control unit 151 controls the first motor 131 to rotate the feed roller 112 at a first intermediate speed V2a and a second intermediate speed V2b, which are higher than the initial speed V1 when feeding the first medium, during the separation period when feeding the second or subsequent medium. The separation period when feeding the second or subsequent medium is the period from time T4 to time T5 in FIGS. 10 to 12 . In particular, when feeding the second or subsequent medium among the media placed on the mounting table 103, the control unit 151 controls the first motor 131 to rotate the feed roller 112 at the first intermediate speed V2a and then at the second intermediate speed V2b. In this way, the control unit 151 reduces the speed of the feed roller 112 during the separation period of the second or subsequent medium, and then gradually increases the speed to a speed higher than the speed during the separation period of the first medium. This enables the control unit 151 to reduce the processing time required for the media reading process while preventing the occurrence of double feeding or jamming of media and loss of synchronization of the first motor 131, thereby achieving both feeding performance (reduced occurrence of abnormalities) and processing performance (reduced transport time).

[0105] Figure 14 is a schematic diagram for explaining the technical significance of feeding a medium in accordance with the medium reading process shown in Figures 8 and 9. Figure 14 is a schematic diagram of lower guide 101a of lower housing 101 as seen from above.

[0106] FIG. 14 shows a state in which the leading edge of medium M3, which has been transported at an angle, is in contact with only one of the two transport rollers 119 (first opposing roller 120). If the speed of the transport roller 119 is substantially the same as the speed of the feed roller 112, medium M3 is subsequently transported downstream while maintaining its current inclination. However, if the speed of the transport roller 119 is higher than the speed of the feed roller 112, medium M3 is subsequently pulled by the transport roller 119 with which it is in contact and rotates in the direction of arrow A9. Therefore, the inclination of medium M3 increases, and medium M3 may collide with the side wall of the transport path, resulting in a medium jam. The greater the difference between the speed of the transport roller 119 and the speed of the feed roller 112, the greater the likelihood of a medium jam occurring.

[0107] As described above, when the leading edge of the medium passes the position of the fifth medium sensor 118, if there is insufficient free space in the storage device 140 or if the distance between the media is short, the control unit 151 may temporarily stop feeding of the medium. However, if the control unit 151 temporarily stops feeding of the medium, a certain amount of through-up period is required after the control unit 151 resumes feeding of the medium and before the speed of the feed roller 112 reaches the set speed. If the speed of the feed roller 112 has not increased sufficiently when the leading edge of the medium reaches the position of the transport roller 119, skew of the medium may occur. Therefore, when the control unit 151 temporarily stops feeding of the medium, it is necessary to stop the medium at a position sufficiently upstream of the transport roller 119. However, a certain amount of through-down period is required after the control unit 151 stops the first motor 131 and before the rotation of the feed roller 112 completely stops. For example, the above problem can be avoided by making the distance between the feed roller 112 and the transport roller 119 sufficiently large, but in that case, the size of the entire device increases.

[0108] As shown in steps S106 and S119 in FIGS. 8 and 9 , in high-speed mode, after the fifth medium sensor 118 detects the leading edge of the medium, the control unit 151 controls the first motor 131 to rotate the feed roller 112 at final speed V3a, which is higher than the second intermediate speed V2b. Therefore, when the leading edge of the medium passes the position of the fifth medium sensor 118, the speed of the feed roller 112 is set to second intermediate speed V2b, which is lower than final speed V3a, and the control unit 151 can completely stop the rotation of the feed roller 112 in a sufficiently short time. Note that in medium-speed mode and low-speed mode, the speed of the feed roller 112 is set to final speed V3b and final speed V3c when the leading edge of the medium passes the position of the fifth medium sensor 118. However, because final speed V3b and final speed V3c are lower than final speed V3a, the control unit 151 can completely stop the rotation of the feed roller 112 in a sufficiently short time.

[0109] Therefore, when the control unit 151 temporarily stops feeding of the medium, it can stop the medium at a position sufficiently upstream of the conveyance roller 119. As a result, when the control unit 151 resumes feeding of the medium, it can sufficiently increase the speed of the feed roller 112 before the leading edge of the medium reaches the position of the conveyance roller 119, thereby suppressing an increase in the tilt of the medium and preventing the occurrence of a medium jam.

[0110] Furthermore, as shown in steps S114 and S115 of FIG. 9 , during the separation period when feeding the second or subsequent media, when the second media sensor 114 detects the leading edge of the medium, the control unit 151 controls the first motor 131 to rotate the feed roller 112 at the second intermediate speed V2b. After the leading edge of the medium passes the position of the second media sensor 114, that is, after it passes through the nip area between the feed roller 112 and the brake roller 113, the leading edge of the medium does not collide with the brake roller 113 and lift up. Therefore, the possibility of the medium buckling and causing a media jam is low. When the second media sensor 114 detects the leading edge of the medium, the control unit 151 determines that the leading edge of the medium has passed through the nip area between the feed roller 112 and the brake roller 113, and increases the speed of the feed roller 112. This enables the control unit 151 to reduce the media feeding time while suppressing the occurrence of media jams.

[0111] In particular, by shortening the period during which the feed roller 112 rotates at the first intermediate speed V2a and lengthening the period during which it rotates at the second intermediate speed V2b, the total medium feed speed can be increased even if the second intermediate speed V2b is low. In other words, the control unit 151 can lower the second intermediate speed V2b, and when temporarily stopping the medium feeding as described above, the medium can be stopped at a position sufficiently upstream of the conveyance roller 119. Note that in steps S114 and S115 of FIG. 9 , the control unit 151 may change the speed of the feed roller 112 when a fourth predetermined time has elapsed since the start of medium feeding, rather than when the leading edge of the medium passes the position of the second medium sensor 114. The fourth predetermined time is set, based on prior experiments, to the time required from the start of medium feeding until the leading edge of the medium passes the nip area between the feed roller 112 and the brake roller 113. In this case, the second medium sensor 114 may be omitted. Also, if the second medium sensor 114 is omitted, the fifth medium sensor 118 may be placed in the position of the second medium sensor 114.

[0112] Furthermore, the control unit 151 may increase the amount of current supplied to the first motor 131 and / or the second motor 132 during the through-up period of the first motor 131 and / or the second motor 132. This reduces the possibility of each motor losing synchronization even if the speed of each motor is increased in a short period of time, and makes it possible to reduce the distance required for through-up. Furthermore, by limiting the period during which the amount of current is increased to the through-up period, the medium conveying device 100 can suppress an increase in overall power consumption.

[0113] Furthermore, as shown in FIG. 13(b), a medium that enters the nip area between the feed roller 112 and the brake roller 113 is pushed back by the brake roller 113, which rotates in the opposite direction to the medium feeding direction. The greater the ratio of the speed of the brake roller 113 to the speed of the feed roller 112, the more effectively the medium is pushed back. In particular, as shown in FIG. 13(a), when feeding of the first medium M1 begins, the leading edges of the media positioned above the first medium M1 have not yet reached the nip area between the feed roller 112 and the brake roller 113. Therefore, when feeding of the first medium M1 begins, each medium enters the nip area between the feed roller 112 and the brake roller 113 with force. Therefore, when feeding the first medium M1, the ratio of the speed of the brake roller 113 to the speed of the feed roller 112 needs to be set to a relatively large value so that the other media can be effectively returned to the upstream side.

[0114] 13(b), when the second or subsequent medium M2 is fed, the leading edge of each medium M2 is already in contact with the brake roller 113. Therefore, when feeding the second or subsequent medium M2, even if the ratio of the speed of the brake roller 113 to the speed of the feed roller 112 is set to a relatively small value, media other than the medium being fed are successfully pushed back.

[0115] As described above, the brake roller 113 is driven by the same second motor 132 as the conveyance roller 119 and discharge roller 123. This allows the medium conveyance device 100 to reduce the number of motors, thereby reducing the cost and size of the device. However, if the speed of the brake roller 113 is reduced, the speeds of the conveyance roller 119 and discharge roller 123 also decrease, resulting in reduced media processing performance.

[0116] Furthermore, the higher the speed of the brake roller 113, the greater the vibration of the brake roller 113, resulting in a loud vibration noise (so-called chatter noise). When starting to feed the second or subsequent medium, the medium is in contact with the brake roller 113 and vibration is suppressed, but when starting to feed the first medium M1, the medium is not in contact with the brake roller 113 and vibration is not suppressed. Therefore, it is desirable to reduce the speed of the brake roller 113, especially when starting to feed the first medium M1.

[0117] As shown in steps S103 and S106 of FIG. 8 , the control unit 151 sets the rotational speed of the brake roller 113 during the separation period when feeding the first medium among the media placed on the mounting table 103 to a speed lower than the rotational speed of the brake roller 113 during the separation period when feeding the second or subsequent media. This allows the control unit 151 to suppress vibration of the brake roller 113 when feeding the first medium, thereby suppressing the generation of vibration noise. During the separation period when feeding the first medium, the conveyance roller 119 has not yet conveyed the medium, so reducing the rotational speed of the brake roller 113 does not increase the medium conveyance time. Meanwhile, the control unit 151 increases the rotational speed of the brake roller 113 during the separation period when feeding the second or subsequent media, thereby enabling the rotational speed of the conveyance roller 119 to be maintained high. Therefore, the medium conveyance device 100 can improve processing performance (reduction of conveyance time) while suppressing increases in device cost and device size.

[0118] 8, when starting to feed a medium, the control unit 151 sets the speed of the feed roller 112 to a sufficiently low initial speed V1, and sets the initial speed U1 of the brake roller 113 to a speed higher than half the initial speed V1 of the feed roller 112. That is, the control unit 151 sets the rotational speed of the brake roller 113 so that the speed of the brake roller 113 during the separation period when feeding the first medium among the media placed on the mounting table 103 is higher than half the speed of the feed roller 112 during the separation period when feeding the first medium. This allows the brake roller 113 to effectively push back a medium that has entered the nip area between the feed roller 112 and the brake roller 113 when feeding a medium.

[0119] As described above in detail, the medium conveying device 100 gradually increases the rotational speed of the feed roller 112 during the period from when the medium feeding starts until the leading edge of the medium passes the feed roller 112. This allows the medium conveying device 100 to reduce the medium feeding time while appropriately controlling the stopping and restart of medium feeding in cases such as when the storage device 140 is low on free space or when the distance between successively fed media is short. Therefore, the medium conveying device 100 can better control the feeding of media.

[0120] In particular, by devising a motor control method, medium conveying device 100 is able to better control the feeding of media without using a specially configured motor or media sensor. Therefore, medium conveying device 100 better controls the feeding of media while suppressing increases in device cost and device size.

[0121] Furthermore, the medium conveying device 100 rotates the feed roller 112 at a low speed while separating the medium, and rotates the feed roller 112 at a high speed when the medium is not being separated, thereby enabling the medium to be conveyed in a short time while being separated well.

[0122] FIG. 15 is a schematic diagram for explaining the drive sources of the feed roller 112, the brake roller 113, the conveying roller 219, the first opposing roller 220, the discharge roller 223 and / or the second opposing roller 224 in a medium conveying device according to another embodiment.

[0123] 15, the medium conveying device according to this embodiment has a conveying roller 219, a first opposing roller 220, a discharge roller 223, and a second opposing roller 224 instead of the conveying roller 119, the first opposing roller 120, the discharge roller 123, and the second opposing roller 124. The medium conveying device also has a second motor 232 instead of the second motor 132.

[0124] The conveying roller 219 is provided in the lower housing 101, and the first opposing roller 220 is provided in the upper housing 102 above the conveying roller 219. The discharge roller 223 is provided in the lower housing 101, and the second opposing roller 224 is provided in the upper housing 102 above the discharge roller 223.

[0125] The second motor 232 is provided in the lower housing 101 separately from the first motor 131, and is connected to the conveying rollers 219, the discharge rollers 223, and the brake roller 113 via a second transmission mechanism 232a to drive the conveying rollers 219, the discharge rollers 223, and the brake roller 113. The second motor 232 generates driving forces for driving the conveying rollers 219, the discharge rollers 223, and the brake roller 113 in response to control signals from the processing circuit 150. The second transmission mechanism 232a includes one or more pulleys, belts, gears, etc. provided between the second motor 232 and the shaft 219a of the conveying roller 219, the shaft 223a of the discharge roller 223, and the shaft 113a of the brake roller 113. In particular, one or more gears are provided between the shaft 219a of the conveyance roller 219 and / or the shaft 223a of the discharge roller 223 and the shaft 113a of the brake roller 113 to vary the rotation direction and rotation speed of each roller. These gears are arranged outside the medium conveyance path in the width direction A8 so as to transmit driving force across the medium conveyance path. The second transmission mechanism 232a transmits driving force generated by the second motor 232 to the conveyance roller 219, discharge roller 223, and brake roller 113. As a result, the second motor 232 rotates the conveyance roller 219, discharge roller 223, and brake roller 113, causing the conveyance roller 219, discharge roller 223, and brake roller 113 to feed, convey, and discharge the medium. The second motor 232 is an example of a drive source for the brake roller 113.

[0126] The first opposing roller 220 is a driven roller that rotates following the conveyance roller 219, and the second opposing roller 224 is a driven roller that rotates following the discharge roller 223. The first opposing roller 220 and / or the second opposing roller 224 may be driven by a driving force from a second motor 232. In this case, one or more gears are further provided between the shaft 219a of the conveyance roller 219 and the shaft 220a of the first opposing roller 220, and / or between the shaft 223a of the discharge roller 223 and the shaft 224a of the second opposing roller 224. The second transmission mechanism 232a further transmits the driving force generated by the second motor 232 to the first opposing roller 220 and / or the second opposing roller 224.

[0127] As described above in detail, the medium conveying device is now able to better control the feeding of the medium even when the conveying roller 219 is provided in the lower housing 101 and the conveying roller 219 and the brake roller 113 are driven by the same second motor 232.

[0128] FIG. 16 is a flowchart showing an example of a portion of the operation of a medium reading process of a medium conveying device according to another embodiment.

[0129] The flowchart shown in Fig. 16 is executed instead of the flowchart shown in Fig. 9. The processes of steps S211 to S213 and S216 to S223 in Fig. 16 are similar to the processes of steps S111 to S113 and S116 to S123 in Fig. 9, so their explanation will be omitted and only steps S214 to S215 will be explained below.

[0130] After the control unit 151 drives the feed roller 112 in step S213, the determination unit 152 determines whether skew of the transported medium has occurred (step S214). The determination unit 152 periodically acquires a third medium signal and a fourth medium signal from the third medium sensor 116 and the fourth medium sensor 117, and determines whether skew of the medium has occurred based on the acquired third medium signal and fourth medium signal. The determination unit 152 determines that the leading edge of the medium has passed the position of the third medium sensor 116 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 determination unit 152 also determines that the leading edge of the medium has passed the position of the fourth medium sensor 117 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.

[0131] The determination unit 152 determines that medium skew has occurred if the leading edge of the medium passes one of the positions of the third medium sensor 116 and the fourth medium sensor 117, but does not pass the other position within a fifth predetermined time. The fifth predetermined time is set, based on a prior experiment, to a value between the difference in the passage time between the positions of the sensors when a medium jam does not occur and the difference in the passage time between the positions of the sensors when a medium jam occurs. On the other hand, the determination unit 152 determines that medium skew has not occurred if the leading edge of the medium passes one of the positions of the third medium sensor 116 and the fourth medium sensor 117, but passes the other position within the fifth predetermined time.

[0132] Next, the control unit 151 changes the speed of the feed roller 112 (step S215). Similar to the process of step S115, when the transport mode is set to the medium speed mode, the control unit 151 changes the speed of the feed roller 112 to the final speed V3b, and when the transport mode is set to the low speed mode, the control unit 151 does not change the speed of the feed roller 112. On the other hand, when the transport mode is set to the high speed mode, the control unit 151 changes the speed of the feed roller 112 based on the determination result of the skew of the medium.

[0133] FIG. 17 is a graph for explaining the speed change of the feed roller 112 in the high-speed mode.

[0134] In Figure 17, graph G41 shows the change in speed of the feed roller 112. The horizontal axis of graph G41 represents time, and the vertical axis represents speed. The speeds of the brake roller 113 and the conveying roller 119 change in the same way as graphs G12 and G13 shown in Figure 10. Graphs G14 and G15 show the change in the signal values ​​of the fifth medium sensor 118 and the sixth medium sensor 121, and change in the same way as graphs G14 and G15 shown in Figure 10. Times T1 to T6 represent the same times as times T1 to T6 shown in Figure 10.

[0135] When medium skew occurs, the control unit 151 changes the speed of the feed roller 112 to a second intermediate speed V2b, as shown in graph G11 in FIG. 10. On the other hand, when medium skew does not occur, the control unit 151 changes the speed of the feed roller 112 to a final speed V3a, as shown in graph G41 in FIG. 17. In this case, the final speed V3a is an example of the second speed. The final speed V3a is set to the same speed as the speed of the feed roller 112. That is, when the determination unit 152 determines that medium skew has occurred, the control unit 151 sets the second speed to the second intermediate speed V2b so that the speed of the feed roller 112 is lower than the speed of the transport roller 119. On the other hand, when the determination unit 152 does not determine that medium skew has occurred, the control unit 151 sets the second speed to the final speed V3a so that the speed of the feed roller 112 is the same as the speed of the transport roller 119.

[0136] As described above, if the storage device 140 does not have enough free space or if the distance between the media is short, the control unit 151 may temporarily stop feeding of the media. However, if the media are tilted and the speed of the transport roller 119 is higher than the speed of the feed roller 112, the tilt of the media increases, and the media may collide with the side wall of the transport path, causing a media jam. By setting the speed of the feed roller 112 to the second intermediate speed V2b when skew of the media occurs, the control unit 151 can stop the media at a position sufficiently upstream of the transport roller 119 when temporarily stopping the feeding of the media. This allows the control unit 151 to sufficiently increase the speed of the feed roller 112 by the time the leading edge of the medium reaches the position of the transport roller 119 when resuming feeding of the media, thereby preventing an increase in the tilt of the media and preventing a media jam.

[0137] On the other hand, if the medium is not skewed, even if the speed of the transport roller 119 is higher than the speed of the feed roller 112, the possibility of the medium becoming more skewed and causing a medium jam is low. If the medium is not skewed, the control unit 151 can reduce the medium feeding time by setting the speed of the feed roller 112 to the final speed V3a. Therefore, the control unit 151 can reduce the medium transport time while suppressing the occurrence of medium jams.

[0138] As described above in detail, the medium transport device is now able to better control the feeding of the medium even when changing the speed of the feed roller 112 depending on whether or not skew of the medium has occurred.

[0139] FIG. 18 is a flowchart showing an example of a portion of the operation of a medium reading process of a medium conveying device according to yet another embodiment.

[0140] The flowchart shown in Fig. 18 is executed in place of the flowchart shown in Fig. 8. The processes of steps S301 to S306 and S308 to S311 in Fig. 18 are similar to the processes of steps S101 to S106 and S107 to S110 in Fig. 8, so their explanations will be omitted and only steps S307 and S312 will be explained below.

[0141] After waiting until the leading edge of the medium passes the position of the fifth medium sensor 118 in step S305 or S118, i.e., after the leading edge of the medium passes the position of the ultrasonic sensor 115, the control unit 151 detects the thickness of the medium being transported (step S307). The control unit 151 detects the thickness of the medium based on the ultrasonic signal received from the ultrasonic sensor 115. The ultrasonic waves emitted by the ultrasonic transmitter 115a and passing through the medium are attenuated by the medium; the thicker the medium, the greater the amount of ultrasonic attenuation. The medium transport device 100 stores in advance in the storage device 140 a table that defines the relationship between the magnitude of the ultrasonic waves received by the ultrasonic receiver 115b, i.e., the signal value of the ultrasonic signal, and the thickness of the medium. The control unit 151 references the table stored in the storage device 140 and identifies the thickness of the medium corresponding to the signal value of the received ultrasonic signal.

[0142] The control unit 151 may further determine whether a multifeed of media has occurred based on the ultrasonic signal received from the ultrasonic sensor 115. When multiple media are transported overlapping one another, the ultrasonic waves that pass through the media are attenuated by the air gap between the overlapping media. Therefore, the control unit 151 can determine whether a multifeed of media has occurred based on whether the signal value of the ultrasonic signal is equal to or less than the multifeed threshold. The multifeed threshold is set to a value between the signal value of the ultrasonic signal when one sheet of paper is transported and the signal value of the ultrasonic signal when two sheets of paper are transported. If it is determined that a multifeed of media has occurred, the control unit 151 stops the first motor 131 and the second motor 132 to stop the transport and discharge of the media. The control unit 151 may also stop the medium reading process after discharging the currently transported medium. The control unit 151 may also drive each motor and control each roller to reverse the media remaining in the transport path, return them to the mounting table 103, and then re-feed (separate) them. This eliminates the need for the user to re-place the medium on the mounting table 103 and re-feed it, allowing the control unit 151 to improve user convenience. The control unit 151 may also notify the user by displaying information indicating that a duplicated medium feed has occurred on the display device 106 or by transmitting the information to the information processing device via the interface device 135.

[0143] The control unit 151 may also detect the thickness of the medium using a thickness sensor other than the ultrasonic sensor 115. The thickness sensor is located at the same position as the ultrasonic sensor 115. The thickness sensor may also be located at any position on the medium transport path. The thickness sensor is, for example, a reflected light sensor including a pair of a light emitter and a light receiver on one side of the medium transport path and a pair of a light emitter and a light receiver on the other side. The reflected light sensor detects the distance between each pair and each surface 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 reflected light sensor generates a thickness signal indicating the thickness by subtracting each detected distance from the distance between the two pairs. The medium transport device 100 pre-stores a table in the storage device 140 that defines the relationship between the signal value of the thickness signal and the thickness of the medium. The control unit 151 refers to the table stored in the storage device 140 and identifies the thickness of the medium corresponding to the signal value of the received thickness signal. Note that the thickness sensor is not limited to one that uses light, and any other sensor that can detect the thickness of the medium, such as a pressure sensor or a thickness sensor that uses a contact piece, may be used as the thickness sensor.

[0144] Meanwhile, after waiting until the trailing edge of the medium passes the position of the fifth medium sensor 118 in step S311, the control unit 151 detects the size of the medium being transported (step S312). For example, the control unit 151 detects the length of the medium in the medium transport direction A1 as the size of the medium. The control unit 151 detects the length of the medium in the medium transport direction A1 based on the fifth medium signal received from the fifth medium sensor 118. The control unit 151 calculates the length of the medium in the medium transport direction A1 as the distance moved by the feed roller 112 by driving the first motor 131 from when the fifth medium sensor 118 detects the leading edge of the medium to when it detects the trailing edge of the medium. In other words, the control unit 151 calculates the length of the medium in the medium transport direction A1 as the value obtained by multiplying the time from when the fifth medium sensor 118 detects the leading edge of the medium to when it detects the trailing edge of the medium by the medium transport speed.

[0145] The control unit 151 may detect the length of the medium in the width direction A8 as the size of the medium. In this case, the medium conveying device 100 arranges multiple fifth medium sensors 118 at intervals in the width direction A8 and stores in advance the arrangement intervals of the fifth medium sensors 118. The control unit 151 detects the length of the medium in the width direction A8 based on the distance between the outermost fifth medium sensors 118 that detect the conveyed medium.

[0146] Furthermore, when imaging of the medium is completed, the control unit 151 may detect the length of the medium in the medium transport direction A1 or the length of the medium in the width direction A8 based on the input image generated by the imaging device 122. In this case, the control unit 151 uses a known image processing technique to detect the ends (edges) of the medium from the input image, and detects the length of the medium in the medium transport direction A1 or the width direction A8 based on the distance between the top and bottom edges or the distance between the left and right edges of the medium.

[0147] When the flowchart shown in FIG. 18 is executed, in steps S115 and / or S119 of the flowchart shown in FIG. 9, the control unit 151 changes the speed of the feed roller 112 based on the length of the medium.

[0148] FIG. 19 is a graph for explaining the change in speed of the feed roller 112 in the high-speed mode.

[0149] In Figure 19, graphs G51 and G52 show an example of the change in speed of the feed roller 112. The horizontal axis of graphs G51 and G52 represents time, and the vertical axis represents speed. The speeds of the brake roller 113 and the conveying roller 119 change in the same way as graphs G12 and G13 shown in Figure 10. Graphs G14 and G15 show changes in the signal values ​​of the fifth medium sensor 118 and the sixth medium sensor 121, and change in the same way as graphs G14 and G15 shown in Figure 10. Times T1 to T6 represent the same times as times T1 to T6 shown in Figure 10.

[0150] In step S115, if the medium size is equal to or smaller than the first size threshold and greater than the second size threshold, the control unit 151 changes the speed of the feed roller 112 to a second intermediate speed V2b, as shown in graph G11 in FIG. 10. For example, the first size threshold is set to a value between A4 portrait and A3 portrait when the medium size is the length of the medium in the medium transport direction A1, and is set to a value between A4 landscape and A3 landscape when the medium size is the length of the medium in the width direction A8. The second size threshold is set to a value smaller than the first size threshold. For example, the second size threshold is set to a value between A5 portrait and A4 portrait when the medium size is the length of the medium in the medium transport direction A1, and is set to a value between A5 landscape and A4 landscape when the medium size is the length of the medium in the width direction A8. The first size threshold and the second size threshold are examples of size thresholds.

[0151] On the other hand, when the medium size is larger than the first size threshold, the control unit 151 changes the speed of the feed roller 112 to a second intermediate speed V2c, as shown in graph G51. The second intermediate speed V2c is set to a speed higher than the second intermediate speed V2b when the medium size is equal to or smaller than the first size threshold but larger than the second size threshold, and lower than the final speed V3a. Furthermore, when the medium size is equal to or smaller than the second size threshold, the control unit 151 changes the speed of the feed roller 112 to a second intermediate speed V2d, as shown in graph G52. The second intermediate speed V2d is set to a speed lower than the second intermediate speed V2b when the medium size is equal to or smaller than the first size threshold but larger than the second size threshold, and higher than the first intermediate speed V2a.

[0152] Furthermore, in step S119, when the medium size is equal to or smaller than the first size threshold and greater than the second size threshold, the control unit 151 changes the speed of the feed roller 112 to final speed V3a, as shown in graph G11 in FIG. On the other hand, when the medium size is greater than the first size threshold, the control unit 151 changes the speed of the feed roller 112 to final speed V3d, as shown in graph G51. Final speed V3d is set to a speed higher than the final speed V3a when the medium size is equal to or smaller than the first size threshold and greater than the second size threshold. Note that when the control unit 151 changes the speed of the feed roller 112 to final speed V3d, it may also change the speed of the feed roller 112 to final speed V3a before the leading edge of the following medium passes the position of the fifth medium sensor 118, as shown by dotted line D1 in graph G51. That is, the control unit 151 decelerates the speed of the feed roller 112 to the final speed V3a before the leading edge of the trailing medium passes the position of the conveyance roller 119. This allows the control unit 151 to prevent the medium from being pushed by the feed roller 112 and bending between the feed roller 112 and the conveyance roller 119, causing a medium jam. Furthermore, when the size of the medium is equal to or smaller than the second size threshold, the control unit 151 changes the speed of the feed roller 112 to the second intermediate speed V2b, as shown in graph G52.

[0153] When the size of the medium is larger than the first size threshold, the control unit 151 may change the speed of the feed roller 112 to the same speed as when the size of the medium is equal to or smaller than the first size threshold and larger than the second size threshold. Alternatively, when the size of the medium is equal to or smaller than the second size threshold, the control unit 151 may change the speed of the feed roller 112 to the same speed as when the size of the medium is equal to or smaller than the first size threshold and larger than the second size threshold.

[0154] In this way, when the size of the preceding medium is small, the control unit 151 sets the speed of the feed roller 112 after the leading edge of the following medium has passed through the nip area between the feed roller 112 and the brake roller 113 to be lower than the speed when the size of the preceding medium is large. That is, the control unit 151 sets the second speed when the size of the preceding medium is equal to or smaller than the size threshold to a speed lower than the second speed when the size of the preceding medium is larger than the size threshold.

[0155] Generally, the shorter the length of the medium, the shorter the distance between successively transported media tends to be. By setting the speed of the feed roller 112 when the preceding medium is small to be slower than the speed of the feed roller 112 when the preceding medium is large, the control unit 151 can prevent successively transported media from colliding with each other.

[0156] When the flowchart shown in FIG. 18 is executed, in steps S115 and / or S119 of the flowchart shown in FIG. 9, the control unit 151 may change the speed of the feed roller 112 based on the thickness of the medium.

[0157] In step S114, if the thickness of the medium is equal to or less than the first thickness threshold and greater than the second thickness threshold, the control unit 151 changes the speed of the feed roller 112 to a second intermediate speed V2b, as shown in graph G11 in FIG. 10. For example, the first thickness threshold is set to a value between the thickness of PPC (Plain Paper Copier) paper and the thickness of a typical business card. The second thickness threshold is set to a value smaller than the first thickness threshold. For example, the second thickness threshold is set to a value between the thickness of typical thin paper and the thickness of PPC paper. The first thickness threshold and the second thickness threshold are examples of thickness thresholds.

[0158] On the other hand, when the thickness of the medium is greater than the first thickness threshold, the control unit 151 changes the speed of the feed roller 112 to a second intermediate speed V2c as shown in graph G51. When the thickness of the medium is equal to or less than the second thickness threshold, the control unit 151 changes the speed of the feed roller 112 to a second intermediate speed V2d as shown in graph G52.

[0159] Furthermore, in step S119, if the thickness of the medium is equal to or less than the first thickness threshold and greater than the second thickness threshold, the control unit 151 changes the speed of the feed roller 112 to final speed V3a, as shown in graph G11 in Fig. 10. On the other hand, if the thickness of the medium is greater than the first thickness threshold, the control unit 151 changes the speed of the feed roller 112 to final speed V3d, as shown in graph G51. Furthermore, if the size of the medium is equal to or less than the second thickness threshold, the control unit 151 changes the speed of the feed roller 112 to second intermediate speed V2b, as shown in graph G52.

[0160] When the thickness of the medium is greater than the first thickness threshold, the control unit 151 may change the speed of the feed roller 112 to the same speed as when the thickness of the medium is equal to or less than the first thickness threshold and greater than the second thickness threshold. Alternatively, when the thickness of the medium is equal to or less than the second thickness threshold, the control unit 151 may change the speed of the feed roller 112 to the same speed as when the thickness of the medium is equal to or less than the first thickness threshold and greater than the second thickness threshold.

[0161] In this way, when the preceding medium is thin, the control unit 151 sets the speed of the feed roller 112 after the leading edge of the following medium has passed through the nip area between the feed roller 112 and the brake roller 113 to be lower than the speed when the preceding medium is thick. That is, the control unit 151 sets the second speed when the thickness of the preceding medium is equal to or less than the thickness threshold to a speed lower than the second speed when the thickness of the preceding medium is greater than the thickness threshold.

[0162] Generally, the thinner the medium, the more likely it is that the medium will jam. The control unit 151 can prevent the occurrence of medium jams by setting the speed of the feed roller 112 when the preceding medium is thin to be slower than the speed of the feed roller 112 when the preceding medium is thick.

[0163] Note that either the processing of step S307 or S311 may be omitted. Furthermore, the control unit 151 may change the speed of the feed roller 112 based on both the size and thickness of the medium. In this case, the control unit 151 decreases the speed of the feed roller 112 the shorter the preceding medium is, and decreases the speed of the feed roller 112 the thinner the preceding medium is.

[0164] As described above in detail, the media transport device is now able to better control the feeding of media, even when varying the speed of the feed roller 112 based on the size or thickness of the media.

[0165] 20 and 21 are flowcharts showing an example of the operation of a medium reading process of a medium conveying device according to yet another embodiment.

[0166] The flowcharts shown in Figures 20 and 21 are executed in place of the flowcharts shown in Figures 8 and 9. The processes of steps S401 to S407, S409 to S411, S413 to S417, and S422 to S426 in Figures 20 and 21 are similar to the processes of steps S101 to S107, S109 to S111, S114 to S118, and S119 to S123 in Figures 8 and 9, so their explanation will be omitted. Only steps S408, S412, and S418 to S421 will be explained below.

[0167] After waiting until the leading edge of the medium passes the position of the conveying roller 119 in step S407, the control unit 151 controls the first motor 131 to reduce the speed of the feed roller 112 without stopping the feed roller 112 (step S408). That is, when the leading edge of the medium passes the conveying roller 119, the control unit 151 controls the first motor 131 to reduce the rotational speed of the feed roller 112 while allowing the feed roller 112 to continue rotating.

[0168] FIG. 22 is a graph for explaining the speed change of the feed roller 112 in the high-speed mode.

[0169] In FIG. 22, graph G61 shows an example of the change in speed of the feed roller 112. The horizontal axis of graph G61 represents time, and the vertical axis represents speed. Note that the speeds of the brake roller 113 and the conveyance roller 119 change in the same way as graphs G12 and G13 shown in FIG. 10. Graphs G64 and G65 show changes in the signal values ​​of the fifth medium sensor 118 and the sixth medium sensor 121. The horizontal axis of each graph G64 and G65 represents time, and the vertical axis represents the signal value. Furthermore, times T1 to T6 represent the same times as times T1 to T6 shown in FIG. 10. However, in the examples shown in graphs G61, G64, and G65, the distance between the trailing edge of the preceding medium and the leading edge of the following medium is shorter, and the time between times T4 and T5 is shorter, compared to the examples shown in the respective graphs in FIG. 10.

[0170] As shown in graph G61, between time T3 and time T4, when the leading edge of the medium passes the conveying roller 119, the speed of the feed roller 112 decreases but does not become 0. This enables the control unit 151 to reduce the distance between successively fed media and reduce the medium conveying time while suppressing the occurrence of a jam of the medium between the feed roller 112 and the conveying roller 119.

[0171] After waiting until the rear end of the medium passes the position of fifth medium sensor 118 in step S410, if it is determined in step S411 that the medium remains on mounting table 103, control unit 151 changes the speed of feed roller 112 (step S412). As in step S112 of FIG. 9, when the transport mode is set to high-speed mode, control unit 151 sets the speed of feed roller 112 to first intermediate speed V2a.

[0172] After waiting until the leading edge of the medium passes the position of the fifth medium sensor 118 in step S417, the control unit 151 calculates the time from when the trailing edge of the leading medium passes the first position to when the leading edge of the following medium passes the second position (step S418). Hereinafter, the time from when the trailing edge of the leading medium passes the first position to when the leading edge of the following medium passes the second position may be referred to as the medium interval. The first and second positions are set to, for example, the positions of the fifth medium sensor 118. In this case, the control unit 151 calculates the medium interval as the time from when the trailing edge of the leading medium passes the position of the fifth medium sensor 118 in step S410 to when the leading edge of the following medium passes the position of the fifth medium sensor 118 in step S417. The first and second positions may be any other positions, such as the position of the second medium sensor 114. Furthermore, the first and second positions are not limited to being the same position and may be mutually different positions.

[0173] Next, the control unit 151 determines whether the calculated medium interval is equal to or less than a predetermined time (step S418). If the medium interval is greater than the predetermined time, the control unit 151 moves the process to step S422.

[0174] On the other hand, if the medium interval is equal to or shorter than the predetermined time, the control unit 151 determines the deceleration time for decelerating the feed roller 112 based on the medium interval (step S419). The deceleration time is the time from when the feed roller 112 is stopped until the feed roller 112 resumes rotation, or the time from when the feed roller 112 is decelerated until the feed roller 112 is accelerated.

[0175] The control unit 151 determines the deceleration time so that the shorter the medium interval, the longer the deceleration time, and the longer the medium interval, the shorter the deceleration time. The medium conveying device 100 stores in advance in the storage device 140 a table that defines the relationship between the medium interval and the deceleration time, and the control unit 151 refers to the table stored in the storage device 140 to identify the deceleration time that corresponds to the medium interval.

[0176] Next, the control unit 151 reduces the speed of the feeding roller 112 (step S420).

[0177] 22, when the medium interval (the time from time T4 to time T5) is short, at time T5 when the leading edge of the subsequent medium passes the position of the fifth medium sensor 118, the control unit 151 reduces the speed of the feed roller 112 to a predetermined speed. For example, as shown by the solid line L2 in graph G61, the control unit 151 changes the speed of the feed roller 112 to a speed that is at least lower than the second intermediate speed V2b, thereby decelerating the feed roller 112. Alternatively, the control unit 151 may change the speed of the feed roller 112 to 0 and stop the feed roller 112, as shown by the dotted line D2 in graph G61.

[0178] Next, the control unit 151 waits until the deceleration time determined in step S420 has elapsed (step S421).

[0179] Next, the control unit 151 changes the speed of the feeding roller 112 (step S422).

[0180] As shown in FIG. 22, similarly to the process of step S119 in FIG. 9, when the transport mode is set to the high-speed mode, the control unit 151 changes the speed of the feed roller 112 to the final speed V3a.

[0181] In this way, when the medium interval is equal to or shorter than the predetermined time, the control unit 151 temporarily stops or decelerates the feed roller 112. This allows the control unit 151 to prevent collisions between continuously fed media.

[0182] Furthermore, when the leading edge of the medium following the preceding medium passes the fifth medium sensor 118, the control unit 151 temporarily stops or decelerates the feed roller 112. Then, based on the medium interval, the control unit 151 determines the timing to temporarily stop the feed roller 112 and then resume rotation of the feed roller 112, or the timing to decelerate the feed roller 112 and then accelerate the feed roller 112. This allows the control unit 151 to appropriately set the time for decelerating the feed roller 112, and can prevent collisions between continuously fed media while preventing the medium transport time from increasing too much.

[0183] In step S408, control unit 151 may control first motor 131 to stop feed roller 112, similar to step S108 in Fig. 8. In that case, in step S412, control unit 151 sets the speed of feed roller 112 and drives first motor 131 again, similar to steps S112 and S113 in Fig. 9, thereby restarting the rotation of feed roller 112.

[0184] As described above in detail, the media transport device is now able to better control the feeding of media, even when changing the speed of the feed roller 112 based on the spacing between successively fed media.

[0185] FIG. 23 is a schematic diagram for explaining the drive sources of the feed roller 112, brake roller 113, conveying roller 119, first opposing roller 120, discharge roller 123 and / or second opposing roller 124 in a medium conveying device according to yet another embodiment.

[0186] 23, the medium conveying device according to this embodiment has a first motor 231 instead of the first motor 131. In addition, the medium conveying device has a second transmission mechanism 132b instead of the second transmission mechanism 132a of the second motor 132.

[0187] The first motor 231 is provided in the upper housing 102 and is connected to the feed roller 112 and the brake roller 113 via a first transmission mechanism 231a, and drives the feed roller 112 and the brake roller 113. The first motor 231 generates a driving force for driving the feed roller 112 and the brake roller 113 in response to a control signal from the processing circuit 150. The first transmission mechanism 231a includes one or more pulleys, belts, gears, etc., provided between the first motor 231 and the shaft 113a of the brake roller 113 and the shaft 112a of the feed roller 112. The first transmission mechanism 231a transmits the driving force generated by the first motor 231 to the feed roller 112 and the brake roller 113. In particular, one or more gears are provided between the shaft 113a of the brake roller 113 and the shaft 112a of the feed roller 112 to vary the rotation direction and rotation speed of each roller. These gears are arranged outside the medium transport path in the width direction A8 so as to transmit driving force across the medium transport path. As a result, the first motor 231 rotates the feed roller 112 and the brake roller 113 to feed the medium. The first motor 231 is an example of a drive source for the brake roller 113.

[0188] Furthermore, by providing the first motor 231 in the housing on the brake roller 113 side (upper housing 102), the driving force can be reliably transmitted to the brake roller 113 before the feed roller 112. This allows the first motor 231 to start rotating the brake roller 113 before starting rotation of the feed roller 112, making it possible to stably separate the media. Furthermore, it is preferable that the first motor 231 and the shaft 113a of the brake roller 113 are directly connected by a belt. This allows the first motor 231 to more reliably start rotating the brake roller 113 before starting rotation of the feed roller 112.

[0189] The second motor 132 is provided in the upper housing 102 separately from the first motor 231, and is connected to the transport roller 119 and the discharge roller 123 via a second transmission mechanism 132b to drive the transport roller 119 and the discharge roller 123. The second motor 132 generates a driving force for driving the transport roller 119 and the discharge roller 123 in response to a control signal from the processing circuit 150. The second transmission mechanism 132b includes one or more pulleys, belts, gears, etc., provided between the second motor 132 and the shaft 119a of the transport roller 119 and the shaft 123a of the discharge roller 123. The second transmission mechanism 132b transmits the driving force generated by the second motor 132 to the transport roller 119 and the discharge roller 123. As a result, the second motor 132 rotates the transport roller 119 and the discharge roller 123, causing the transport roller 119 and the discharge roller 123 to transport and discharge the medium.

[0190] 24 and 25 are flowcharts showing an example of the operation of a medium reading process of a medium conveying device according to yet another embodiment.

[0191] The flowcharts shown in Figures 24 and 25 are executed in place of the flowcharts shown in Figures 8 and 9. The processing of steps S501 to S507, S509 to S511, S514, S516 to S518, and S520 to S523 in Figures 24 and 25 is the same as the processing of steps S101 to S107, S109 to S111, S114, S116 to S118, and S120 to S123 in Figures 8 and 9, so description thereof will be omitted. Only steps S508, S512 to S513, S515, and S519 will be described below.

[0192] After waiting until the leading edge of the medium passes the position of the conveying roller 119 in step S507, the control unit 151 controls the first motor 231 to stop or decelerate the brake roller 113 together with the feed roller 112 (step S508). The medium conveying device 100 has a first mode that prioritizes ensuring the distance between media, and a second mode that prioritizes preventing the occurrence of double feeding of media. The first mode and the second mode are set by the user using the operation device 105 or an information processing device.

[0193] FIG. 26 is a graph for explaining the speed changes of the feed roller 112, the brake roller 113, and the transport roller 119 in the high-speed mode.

[0194] 26, graph G71 shows an example of the speed change of the feed roller 112, graph G72 shows an example of the speed change of the brake roller 113, and graph G73 shows an example of the speed change of the transport roller 119. The horizontal axis of each of graphs G71 to G73 represents time, and the vertical axis represents speed. Graphs G14 and G15 show changes in the signal values ​​of the fifth medium sensor 118 and the sixth medium sensor 121, which change in the same way as graphs G14 and G15 shown in FIG. 10. Times T1 to T6 represent times similar to times T1 to T6 shown in FIG. 10.

[0195] When the first mode is set, the control unit 151 controls the first motor 231 to stop the feed roller 112 and the brake roller 113. In this case, as shown by the solid line L3 of graph G71 and the solid line L4 of graph G72, the speeds of the feed roller 112 and the brake roller 113 become 0 between time T3 and time T4. This enables the control unit 151 to reliably prevent a medium jam from occurring between the feed roller 112 and the conveyance roller 119.

[0196] On the other hand, when the second mode is set, the control unit 151 controls the first motor 231 to continue rotating the feed roller 112 and the brake roller 113 while reducing the rotational speed of the feed roller 112 and the brake roller 113 (without stopping them). In this case, as shown by the dotted line D3 in graph G71 and the dotted line D4 in graph G72, the speeds of the feed roller 112 and the brake roller 113 do not become zero between time T3 and time T4, but are reduced. This allows the control unit 151 to prevent a reduction in separation performance caused by stopping the brake roller 113, and to prevent double feeding of media.

[0197] After waiting until the rear end of the medium passes the position of the fifth medium sensor 118 in step S510, if it is determined in step S511 that the medium remains on the loading table 103, the control unit 151 sets the speed of the feeding roller 112 to feed the subsequent medium (step S512).

[0198] When the first mode is set, the control unit 151 sets the speed of the feed roller 112 to a first intermediate speed V2a at time T4, as shown in graph G71 of Fig. 26. Also, the control unit 151 sets the speed of the brake roller 113 to a first intermediate speed U2a at time T4, as shown in graph G72. The first intermediate speed U2a is set to a speed that is higher than the initial speed U1 and lower than the final speed U3a.

[0199] Next, the control unit 151 controls the first motor 231 to rotate the feed roller 112 and the brake roller 113 at the set speed (step S513). If the first mode is set and the feed roller 112 and the brake roller 113 have been stopped, the control unit 151 restarts the rotation of the feed roller 112 and the brake roller 113 to feed and transport the subsequent medium.

[0200] On the other hand, when the second mode is set and the feed roller 112 and the brake roller 113 are not stopped, the control unit 151 changes the speeds of the feed roller 112 and the brake roller 113. The control unit 151 increases the speed of the feed roller 112 to a first intermediate speed V2a and increases the speed of the brake roller 113 to a first intermediate speed U2a.

[0201] After waiting until the leading edge of the succeeding medium passes the position of second medium sensor 114 in step S514, control unit 151 changes the speed of feed roller 112 and brake roller 113 (step S515).

[0202] 26, the control unit 151 changes the speed of the feed roller 112 to a second intermediate speed V2b. Also, as shown in graph G72, the control unit 151 changes the speed of the brake roller 113 to a second intermediate speed U2b. The second intermediate speed U2b is set to a speed higher than the first intermediate speed U2a and lower than the final speed U3a.

[0203] After waiting until the leading edge of the succeeding medium passes the position of the fifth medium sensor 118 in step S518, the control unit 151 changes the speed of the feed roller 112 and the brake roller 113 (step S519).

[0204] 26, at time T5, the control unit 151 changes the speed of the feed roller 112 to a final speed V3a. Also, as shown in graph G72, the control unit 151 changes the speed of the brake roller 113 to a final speed U3a.

[0205] In step S508, the control unit 151 may control the first electromagnetic clutch 133 to cut off the driving force from the first motor 231 to the feed roller 112 while decelerating the brake roller 113, thereby stopping the feed roller 112. That is, when the leading edge of the medium passes the conveyance roller 119, the control unit 151 controls the first electromagnetic clutch 133 to cut off the driving force from the first motor 231 to the feed roller 112 while continuing to transmit the driving force from the first motor 231 to the brake roller 113. In this case, in step S513, the control unit 151 controls the first electromagnetic clutch 133 to transmit the driving force from the first motor 231 to the feed roller 112, thereby restarting the rotation of the feed roller 112. In this way, the control unit 151 can prevent a decrease in separation performance due to stopping the brake roller 113 and prevent the distance between continuously fed media from becoming narrow.

[0206] In this embodiment, the feed roller 112 and the brake roller 113 are driven by the same first motor 231, so there is a proportional relationship between the speed of the feed roller 112 and the speed of the brake roller 113. The speed of the brake roller 113 is set to be lower than the speed of the feed roller 112 and higher than half the speed of the feed roller 112.

[0207] Furthermore, the medium transport device may operate in either the first mode or the second mode in a fixed manner.

[0208] As described above in detail, the medium transport device is now able to better control the feeding of the medium even when the feed roller 112 and the brake roller 113 are driven by the same first motor 231.

[0209] FIG. 27 is a schematic diagram for explaining the drive sources of the feed roller 112, the brake roller 113, the conveying roller 219, the first opposing roller 220, the discharge roller 223 and / or the second opposing roller 224 in a medium conveying device according to yet another embodiment.

[0210] As shown in FIG. 27 , the medium conveying device according to this embodiment has a conveying roller 219, a first opposing roller 220, a discharge roller 223, and a second opposing roller 224 instead of the conveying roller 119, the first opposing roller 120, the discharge roller 123, and the second opposing roller 124. The configurations of the conveying roller 219, the first opposing roller 220, the discharge roller 223, and the second opposing roller 224 are the same as the configurations of the conveying roller 219, the first opposing roller 220, the discharge roller 223, and the second opposing roller 224 in the medium conveying device shown in FIG. 15 . The medium conveying device also has a second motor 232 instead of the second motor 132. The configuration of the second motor 232 is the same as the configuration of the second motor 232 in the medium conveying device shown in FIG. 15 . The medium conveying device also has a first motor 231 instead of the first motor 131. The configuration of the first motor 231 is the same as the configuration of the first motor 231 in the medium conveying device shown in FIG. 23 .

[0211] That is, in the medium conveying device according to this embodiment, similar to the medium conveying device shown in FIG. 23, the first motor 231 drives the feed roller 112 and the brake roller 113, and the second motor 232 drives the conveying roller 219 and the discharge roller 223.

[0212] As described above in detail, the media conveying device is now able to better control the feeding of media even when the conveying roller 219 is provided in the lower housing 101 and the feed roller 112 and brake roller 113 are driven by the same first motor 231.

[0213] Figure 28 is a schematic diagram for explaining the drive sources of the feed roller 112, brake roller 113, conveying roller 119, first opposing roller 120, discharge roller 123 and / or second opposing roller 124 in a medium conveying device according to yet another embodiment.

[0214] 28, the medium conveying device according to this embodiment has a third motor 336 in addition to the first motor 131. Furthermore, the medium conveying device has a first transmission mechanism 131b instead of the first transmission mechanism 131a of the first motor 131, and has a second transmission mechanism 132b instead of the second transmission mechanism 132a of the second motor 132. The configuration of the second motor 132 is similar to the configuration of the second motor 132 shown in FIG.

[0215] The first motor 131 is connected to the feed roller 112 via a first transmission mechanism 131b and drives the feed roller 112. The first motor 131 generates a driving force for driving the feed roller 112 in response to a control signal from the processing circuit 150. The first transmission mechanism 131b includes one or more pulleys, belts, gears, etc., provided between the first motor 131 and the shaft 112a of the feed roller 112, and transmits the driving force generated by the first motor 131 to the feed roller 112. In this way, the first motor 131 rotates the feed roller 112 to feed the medium.

[0216] The third motor 336 is provided in the upper housing 102 separately from the first motor 131 and the second motor 132, and is connected to the brake roller 113 via a third transmission mechanism 336a to drive the brake roller 113. The third motor 336 generates a driving force for driving the brake roller 113 in response to a control signal from the processing circuit 150. The third transmission mechanism 336a includes one or more pulleys, belts, gears, etc., provided between the third motor 336 and the shaft 113a of the brake roller 113, and transmits the driving force generated by the third motor 336 to the brake roller 113. As a result, the third motor 336 rotates the brake roller 113 to feed the medium. The third motor 336 is an example of a driving source for the brake roller 113.

[0217] FIG. 29 is a flowchart showing an example of a portion of the operation of a medium reading process of a medium conveying device according to yet another embodiment.

[0218] The flowchart shown in Fig. 29 is executed in place of the flowchart shown in Fig. 9. The processes of steps S611, S614 to S615, S616, S618, S620, and S622 to S625 in Fig. 29 are the same as the processes of steps S111, S112 to S113, S116, S117, S118, and S120 to S123 in Fig. 9, and therefore will not be described. Only steps S612 to S613, S617, S619, and S621 will be described below.

[0219] After waiting until the trailing edge of the medium passes the position of the fifth medium sensor 118 in step S110, if it is determined in step S611 that the medium remains on the mounting table 103, the control unit 151 controls the second motor 132 to reduce the speed of the transport rollers 119 (step S612). That is, when the trailing edge of the medium passes the fifth medium sensor 118, the control unit 151 reduces the rotational speed of the transport rollers 119.

[0220] FIG. 30 is a graph for explaining the speed changes of the feed roller 112, the brake roller 113, and the transport roller 119 in the high-speed mode.

[0221] 30, graph G81 shows an example of the speed change of feed roller 112, graph G82 shows an example of the speed change of brake roller 113, and graph G83 shows an example of the speed change of conveyance roller 119. The horizontal axis of each of graphs G81 to G83 represents time, and the vertical axis represents speed. Graphs G14 and G15 show changes in the signal values ​​of fifth medium sensor 118 and sixth medium sensor 121, and change in the same manner as graphs G14 and G15 shown in FIG. 10. Times T1 to T6 represent the same times as times T1 to T6 shown in FIG. 10. Note that control unit 151 may reduce the rotational speed of conveyance roller 119 when the trailing edge of the medium passes second medium sensor 114 instead of fifth medium sensor 118.

[0222] As shown in graph G83, at time T4, when the trailing edge of the medium passes the fifth medium sensor 118, the control unit 151 reduces the speed of the transport roller 119. A force acts on the medium during separation by the feed roller 112 and the brake roller 113, trying to push the medium toward the upstream side. When the trailing edge of the medium separates from the feed roller 112 and the brake roller 113, this force disappears, and the transport speed of the medium tends to increase. By reducing the speed of the transport roller 119 when the trailing edge of the medium passes the feed roller 112 and the brake roller 113, the control unit 151 is able to transport the medium at a stable speed.

[0223] Next, control unit 151 waits until a sixth predetermined time has elapsed (step S613). The sixth predetermined time is set to a time that allows for a delay in feeding of the medium by feed roller 112 by the amount of delay in conveyance of the medium due to deceleration of conveyance roller 119. This allows control unit 151 to delay feeding of the medium by feed roller 112 by the amount of delay in conveyance of the medium by conveyance roller 119, making it possible to convey the medium at a stable speed. Note that the processing of step S613 may be omitted.

[0224] After waiting until the rear end of the medium passes the imaging position in step S616, the control unit 151 controls the second motor 132 to increase the speed of the conveying roller 119 (step S617). That is, when the rear end of the medium passes the imaging position of the imaging device 122, the control unit 151 increases the rotational speed of the conveying roller 119.

[0225] As shown in graph G83 of FIG. 30, the control unit 151 increases the speed of the conveyance roller 119 when the trailing edge of the medium passes the imaging position between time T4 and time T5. By changing the speed of the conveyance roller 119 after the trailing edge of the medium passes the imaging position, the control unit 151 can prevent the medium from expanding or contracting as included in the input image. Furthermore, when the trailing edge of the medium passes the conveyance roller 119 and the first opposing roller 120, the conveying force applied to the medium decreases, and the conveyance speed of the medium tends to decrease. By increasing the speed of the discharge roller 123 after the trailing edge of the medium passes the conveyance roller 119 and the first opposing roller 120, the control unit 151 can convey the medium at a stable speed.

[0226] After acquiring the input image in step S618, the control unit 151 controls the first motor 131 to increase the speed of the feed roller 112 (step S619). That is, when the rear end of the medium passes the conveyance roller 119, the control unit 151 increases the rotation speed of the feed roller 112.

[0227] 30, the control unit 151 increases the speed of the feed roller 112 to the second intermediate speed V2b after the trailing edge of the medium passes the position of the conveyance roller 119 (after the signal value of the graph G15 changes from H to L). In particular, the control unit 151 increases the speed of the feed roller 112 after increasing the speed of the conveyance roller 119. This allows the control unit 151 to prevent the medium from being pushed by the feed roller 112 and bending between the feed roller 112 and the conveyance roller 119, resulting in a jam of the medium.

[0228] As shown by dotted line D5 in graph G81, the control unit 151 may increase the speed of the feed roller 112 to a final speed V3a that is higher than the second intermediate speed V2b after the rear end of the medium passes the position of the conveyance roller 119. This allows the control unit 151 to make up for any delay in the conveyance of the medium by the conveyance roller 119 and the feed roller 112.

[0229] After waiting until the leading edge of the medium passes through fifth medium sensor 118 in step S620, control unit 151 controls first motor 131 to increase the speed of feed roller 112 (step S621).

[0230] As shown by solid line L6 in graph G81 of FIG. 30, the control unit 151 increases the speed of the feed roller 112 to final speed V3a at time T5. As shown by dotted line D6 in graph G81, the control unit 151 may also increase the speed of the feed roller 112 to final speed V3d, which is higher than final speed V3a, at time T5. This allows the control unit 151 to make up for delays in the conveyance of the medium by the conveyance roller 119 and the feed roller 112. When the control unit 151 changes the speed of the feed roller 112 to final speed V3d, the control unit 151 may also change the speed of the feed roller 112 to final speed V3a before the leading edge of the following medium passes the position of the fifth medium sensor 118, as shown by dotted line D7 in graph G81. This allows the control unit 151 to prevent the medium from being pushed by the feed roller 112 and bending between the feed roller 112 and the conveyance roller 119, resulting in a medium jam.

[0231] In this embodiment, the drive source for the feed roller 112, the drive source for the brake roller 113, and the drive sources for the transport roller 119 and the discharge roller 123 are provided separately, so the speed of each roller can be changed at an independent timing, allowing the control unit 151 to flexibly control the feeding and transport of the medium.

[0232] As shown by dotted line D8 in graph G82, the control unit 151 may temporarily stop the brake roller 113 while the trailing edge of the medium passes through the nip area between the feed roller 112 and the brake roller 113, and then resume rotation of the brake roller 113 after the medium has passed the nip area. Alternatively, as shown by dotted line D9 in graph G82, the control unit 151 may reduce the speed of the brake roller 113 while the trailing edge of the medium is passing through the nip area, and then increase the speed of the brake roller 113 to the final speed U3a after the medium has passed the nip area. When the trailing edge of the preceding medium passes through the nip area between the feed roller 112 and the brake roller 113, the load on the brake roller 113 in the medium feeding direction due to the medium is reduced, which may cause the brake roller 113 to rotate vigorously in the direction opposite to the medium feeding direction. At this time, the elastically deformed portions of the feed roller 112 and the brake roller 113 may return to their original shapes, pushing the following medium back upstream. In this case, the leading edge of the following medium may be pushed up (curled up) by the brake roller 113, which may cause a medium jam. The control unit 151 reduces the speed of the brake roller 113 when the trailing edge of the medium passes through the nip area, thereby preventing the leading edge of the following medium from curling up and causing a medium jam.

[0233] Furthermore, the control unit 151 may start the rotation of the brake roller 113 before the rotation of the feed roller 112. This allows the control unit 151 to prevent multiple media placed on the mounting table 103 from collapsing between the feed roller 112 and the brake roller 113, thereby preventing the occurrence of double feeding of media.

[0234] As described above in detail, the medium conveying device drives the feed roller 112, the brake roller 113, and the conveying roller 219 with separate motors, making it possible to better control the feeding of the medium even when the speed of the conveying roller 119 is changed.

[0235] Note that the medium conveying device may drive the brake roller 113 with either the first motor or the second motor even when changing the speed of the conveying roller 119. In this case, the control unit 151 matches the timing of changing the speed of the brake roller 113 with the timing of changing the speed of the feed roller 112 or the conveying roller 119. The control unit 151 may also change the speed of the feed roller 112 or the brake roller 113 by controlling the first electromagnetic clutch 133 or the second electromagnetic clutch 134. The medium conveying device may also have a driving force interruption mechanism such as an electromagnetic clutch between the conveying roller 119 and the second motor, and the control unit 151 may change the speed of the conveying roller 119 by controlling the driving force interruption mechanism.

[0236] FIG. 31 is a schematic diagram for explaining the drive sources of the feed roller 112, the brake roller 113, the conveying roller 219, the first opposing roller 220, the discharge roller 223 and / or the second opposing roller 224 in a medium conveying device according to yet another embodiment.

[0237] As shown in FIG. 31 , the medium conveying device according to this embodiment has a conveying roller 219, a first opposing roller 220, a discharge roller 223, and a second opposing roller 224 instead of the conveying roller 119, the first opposing roller 120, the discharge roller 123, and the second opposing roller 124. The configurations of the conveying roller 219, the first opposing roller 220, the discharge roller 223, and the second opposing roller 224 are the same as the configurations of the conveying roller 219, the first opposing roller 220, the discharge roller 223, and the second opposing roller 224 in the medium conveying device shown in FIG. 15 . The medium conveying device also has a second motor 232 instead of the second motor 132. The configuration of the second motor 232 is the same as the configuration of the second motor 232 in the medium conveying device shown in FIG. 15 . The medium conveying device also has a third motor 336 in addition to the first motor 131. The configurations of the first motor 131 and the third motor 336 are the same as the configurations of the first motor 131 and the third motor 336 in the medium conveying device shown in FIG. 28 .

[0238] That is, in the media conveying device of this embodiment, similar to the media conveying device shown in Figure 28, the first motor 131 drives the feed roller 112, the third motor 336 drives the brake roller 113, and the second motor 232 drives the conveying roller 219 and the discharge roller 223.

[0239] As described above in detail, the medium conveying device is now able to better control the feeding of the medium even when the conveying roller 219 is provided in the lower housing 101 and the feed roller 112, brake roller 113, and conveying roller 219 are driven by separate motors.

[0240] 32 is a flowchart illustrating an example of a portion of the operation of a medium reading process of a medium conveying device according to yet another embodiment. The medium conveying device according to this embodiment has the drive source shown in FIG. 28 or the drive source shown in FIG. 31.

[0241] The flowchart shown in Fig. 32 is executed in place of the flowchart shown in Fig. 9. The processes of steps S711, S714 to S716, S719 to S721, S724, and S727 to S731 in Fig. 32 are the same as the processes of steps S111, S112 to S114, S115 to S117, S118, and S119 to S123 in Fig. 9, and therefore description thereof will be omitted. Only steps S712 to S713, S717 to S718, S722 to S723, and S725 to S726 will be described below. Furthermore, when the flowchart shown in Fig. 32 is executed, steps S301 to S312 in the flowchart shown in Fig. 18 are executed in place of steps S101 to S110 in the flowchart shown in Fig. 8.

[0242] After waiting until the rear end of the medium passes the position of fifth medium sensor 118 in step S311, control unit 151 determines whether the size of the preceding medium is greater than the first size threshold and whether it is greater than the second size threshold (step S712). If the size of the preceding medium is equal to or less than the first size threshold and equal to or greater than the second size threshold, control unit 151 does not perform any particular process and proceeds to step S714.

[0243] On the other hand, if the size of the preceding medium is larger than the first size threshold or smaller than the second size threshold, the control unit 151 waits until a seventh predetermined time has elapsed (step S713). The seventh predetermined time is set, for example, to the time required for image processing when a medium larger than the first size threshold is being transported minus the time required for medium transport. Alternatively, the seventh predetermined time may be set to the maximum stop time when a medium collision occurs in a prior experiment in which media smaller than the second size threshold are continuously transported while changing the stop time of the feed roller 112. Alternatively, the seventh predetermined time may be set to a time that allows for a delay in feeding the medium by the feed roller 112 by the amount of delay in medium discharge caused by decelerating the discharge roller 123 in the process described below.

[0244] That is, when the leading edge of the medium passes the conveyance roller 119 in step S308, the control unit 151 stops the feed roller 112 in step S309. Furthermore, after the trailing edge of the medium passes the position of the fifth medium sensor 118 in step S311, the control unit 151 resumes feeding by the feed roller 112 in step S715. The control unit 151 delays the timing at which feeding by the feed roller 112 resumes when the size of the medium whose trailing edge has passed the position of the fifth medium sensor 118 is larger than the first size threshold, compared to the timing at which feeding by the feed roller 112 resumes when the size of the medium whose trailing edge has passed the position of the fifth medium sensor 118 is equal to or smaller than the first size threshold. Similarly, the control unit 151 delays the timing at which the feed roller 112 resumes feeding when the size of the medium whose trailing end has passed the position of the fifth media sensor 118 is smaller than the second size threshold, compared to the timing at which the feed roller 112 resumes feeding when the size of the medium whose trailing end has passed the position of the fifth media sensor 118 is equal to or larger than the second size threshold.

[0245] FIG. 33 is a graph for explaining the speed changes of the feed roller 112, brake roller 113, and conveyance roller 119 in high-speed mode when the size of the preceding medium is larger than the first size threshold or smaller than the second size threshold.

[0246] 33, graph G91 shows an example of the speed change of the feed roller 112, graph G92 shows an example of the speed change of the brake roller 113, and graph G93 shows an example of the speed change of the transport roller 119. The horizontal axis of each of graphs G91 to G93 represents time, and the vertical axis represents speed. Graphs G14 and G15 show changes in the signal values ​​of the fifth medium sensor 118 and the sixth medium sensor 121, which change in the same way as graphs G14 and G15 shown in FIG. 10. Times T1 to T6 represent times similar to times T1 to T6 shown in FIG. 10.

[0247] As shown in graph G91, when the size of the preceding medium is larger than the first size threshold or smaller than the second size threshold, the control unit 151 delays the timing of resuming feeding by the feed roller 112 at time T4. When a large-sized medium is being transported, the input image size increases, potentially requiring a significant amount of time for image processing. By delaying the timing of resuming feeding when a large-sized medium is being transported, the control unit 151 can smoothly transport the medium without stopping it for image processing, thereby obtaining a high-quality image. Furthermore, as described above, the shorter the length of the medium, the shorter the distance between consecutively transported media tends to be. By delaying the timing of resuming feeding when a small-sized medium is being transported, the control unit 151 can prevent collisions between consecutively transported media. Furthermore, when a large-sized medium or a small-sized medium is being transported, the control unit 151 reduces the speed of the discharge roller 123 in the process described below. In this case, the control unit 151 delays the timing of resuming feeding, thereby enabling the medium to be transported at a stable speed.

[0248] After waiting until the leading edge of the medium passes the position of second medium sensor 114 in step S716, control unit 151 determines whether the size of the preceding medium is greater than the first size threshold and whether it is smaller than the second size threshold (step S717). If the size of the preceding medium is equal to or smaller than the first size threshold and equal to or larger than the second size threshold, control unit 151 does not perform any particular process and proceeds to step S719.

[0249] On the other hand, if the size of the preceding medium is larger than the first size threshold or smaller than the second size threshold, the control unit 151 waits until a seventh predetermined time has elapsed (step S718).

[0250] As shown in graph G91 of FIG. 33, when the size of the preceding medium is larger than the first size threshold or smaller than the second size threshold, the control unit 151 delays the timing of increasing the speed of the feed roller 112 between time T4 and time T5. This allows the control unit 151 to smoothly transport the large-sized medium without stopping it for image processing, thereby obtaining a good image. The control unit 151 also prevents small-sized media from colliding with other media when being transported. The control unit 151 also allows the medium to be transported at a stable speed.

[0251] After acquiring the input image in step S721, the control unit 151 determines whether the size of the preceding medium is greater than a first size threshold and whether it is smaller than a second size threshold (step S722). If the size of the preceding medium is equal to or smaller than the first size threshold and equal to or larger than the second size threshold, the control unit 151 does not perform any particular process and proceeds to step S724.

[0252] On the other hand, if the size of the preceding medium is larger than the first size threshold or smaller than the second size threshold, the control unit 151 controls the second motor 132 to reduce the speed of the transport rollers 119 and the discharge rollers 123 (step S723).

[0253] That is, the control unit 151 sets the rotation speed of the discharge rollers 123 when the size of the medium is larger than the first size threshold to a speed lower than the rotation speed of the discharge rollers 123 when the size of the medium is equal to or smaller than the first size threshold. Also, the control unit 151 sets the rotation speed of the discharge rollers 123 when the size of the medium is smaller than the second size threshold to a speed lower than the rotation speed of the discharge rollers 123 when the size of the medium is equal to or larger than the second size threshold.

[0254] As shown in graph G93 of FIG. 33 , if the size of the preceding medium is larger than the first size threshold or smaller than the second size threshold, the control unit 151 reduces the speed of the discharge rollers 123 between times T4 and T5. When a large-sized medium is discharged, the leading edge of the medium may pass the leading edge of the discharge tray 104, and the weight of the leading edge that has passed the discharge tray 104 may cause the medium to fly out of the discharge tray 104. By reducing the speed of the discharge rollers 123 when a large-sized medium is discharged, the control unit 151 can prevent the medium from flying out of the discharge tray 104. Furthermore, when multiple media of different sizes are discharged, only the smaller-sized medium may be discharged with force, and the trailing edges of the media may not be aligned. By reducing the speed of the discharge rollers 123 when a small-sized medium is discharged, the control unit 151 can improve the alignment of the media.

[0255] After waiting until the leading edge of the medium passes the position of fifth medium sensor 118 in step S724, control unit 151 determines whether the size of the preceding medium is greater than the first size threshold and whether it is smaller than the second size threshold (step S725). If the size of the preceding medium is equal to or smaller than the first size threshold and equal to or larger than the second size threshold, control unit 151 does not perform any particular process and proceeds to step S727.

[0256] On the other hand, if the size of the preceding medium is larger than the first size threshold or smaller than the second size threshold, the control unit 151 waits until a seventh predetermined time has elapsed (step S727).

[0257] That is, after the fifth medium sensor 118 detects the leading edge of the medium in step S724, the control unit 151 increases the rotational speed of the feed roller 112 in step S727. If the size of the preceding medium is larger than the first size threshold, the control unit 151 delays the timing for increasing the rotational speed of the feed roller 112 from the timing for increasing the rotational speed of the feed roller 112 from the timing for increasing the rotational speed of the feed roller 112 from the timing for increasing the rotational speed of the feed roller 112 from the timing for increasing the rotational speed of the feed roller 112 from the size of the preceding medium equal to or smaller than the first size threshold. Similarly, the control unit 151 delays the timing for increasing the rotational speed of the feed roller 112 from ... size of the preceding medium equal to or larger than the second size threshold.

[0258] As shown in graph G91 in FIG. 33, when the size of the preceding medium is larger than the first size threshold or smaller than the second size threshold, the control unit 151 delays the timing of increasing the speed of the feed roller 112 at time T5. This allows the control unit 151 to smoothly transport the large-sized medium without stopping it for image processing, thereby enabling a good image to be obtained. The control unit 151 can also prevent small-sized media from colliding with other media when being transported. The control unit 151 can also transport the medium at a stable speed.

[0259] Note that any of the processes of steps S712-S713, S717-S718, S722-S723, or S725-S726 may be omitted. Furthermore, in steps S712, S717, S722, or S725, the control unit 151 may determine only either whether the medium size is larger than the first size threshold or whether the medium size is smaller than the second size threshold. In this case, the control unit 151 executes the process of step S713, S718, S723, or S726 regardless of whether the medium size is smaller than the second size threshold or whether the medium size is larger than the first size threshold.

[0260] Furthermore, in step S712, S717, or S725, the control unit 151 may determine whether the size of the preceding medium relative to the medium whose trailing edge has passed the position of the fifth medium sensor 118 is greater than the first size threshold and whether it is smaller than the second size threshold. That is, the control unit 151 delays the timing at which feeding by the feed roller 112 resumes when the size of the preceding medium relative to the medium whose trailing edge has passed the position of the fifth medium sensor 118 is greater than the first size threshold, compared to the timing at which feeding by the feed roller 112 resumes when the size of the preceding medium relative to the medium whose trailing edge has passed the position of the fifth medium sensor 118 is equal to or smaller than the first size threshold. Similarly, the control unit 151 delays the timing at which the feed roller 112 resumes feeding when the size of the preceding medium relative to the medium whose rear end has passed the position of the fifth media sensor 118 is smaller than the second size threshold, compared to the timing at which the feed roller 112 resumes feeding when the size of the preceding medium relative to the medium whose rear end has passed the position of the fifth media sensor 118 is equal to or larger than the second size threshold.

[0261] In these cases, the control unit 151 can smoothly transport the large-sized medium without stopping it for image processing, thereby obtaining a good image. Also, the control unit 151 can prevent small-sized media from colliding with other media when being transported.

[0262] 33, the control unit 151 may temporarily stop the brake roller 113 while the trailing edge of the medium is passing through the nip area between the feed roller 112 and the brake roller 113, and then resume rotation of the brake roller 113 after the trailing edge of the medium has passed through the nip area, as shown by the dotted line D8 in G92. Alternatively, as shown by the dotted line D9 in G92, the control unit 151 may reduce the speed of the brake roller 113 while the trailing edge of the medium is passing through the nip area, and then increase the speed of the brake roller 113 after the trailing edge of the medium has passed through the nip area, returning it to the final speed U3a. This allows the control unit 151 to prevent the leading edge of the following medium from curling up and causing a medium jam.

[0263] Furthermore, the control unit 151 may start the rotation of the brake roller 113 before the rotation of the feed roller 112. This allows the control unit 151 to prevent multiple media placed on the mounting table 103 from collapsing between the feed roller 112 and the brake roller 113, thereby preventing the occurrence of double feeding of media.

[0264] As described above in detail, the media transport device is now able to better control the feeding of media even when changing the speed of the discharge roller 123 based on the size of the media.

[0265] Note that the medium conveying device may drive the brake roller 113 with either the first motor or the second motor even when changing the speed of the discharge roller 123. In this case, the control unit 151 matches the timing of changing the speed of the brake roller 113 with the timing of changing the speed of the feed roller 112 or the discharge roller 123. The control unit 151 may also change the speed of the feed roller 112 or the brake roller 113 by controlling the first electromagnetic clutch 133 or the second electromagnetic clutch 134. The medium conveying device may also have a driving force interruption mechanism such as an electromagnetic clutch between the discharge roller 123 and the second motor, and the control unit 151 may change the speed of the conveying roller 119 by controlling the driving force interruption mechanism.

[0266] 34 and 35 are flowcharts showing an example of the operation of a medium reading process of a medium conveying device according to still another embodiment. The medium conveying device according to this embodiment has the drive source shown in FIG. 28 or the drive source shown in FIG. 31.

[0267] The flowcharts shown in Figures 34 and 35 are executed in place of the flowcharts shown in Figures 8 and 9. The processing of steps S801 to S805, S810 to S821, and S823 to S826 in Figures 34 and 35 is the same as the processing of steps S101 to S105, S107 to S118, and S120 to S123 in Figures 8 and 9, so description thereof will be omitted. Only steps S806 to S809 and S822 will be described below.

[0268] After waiting until the leading edge of the medium passes the position of the fifth medium sensor 118 in step S805, the control unit 151 controls the first motor 131 to temporarily stop the feed roller 112 or to reduce the speed of the feed roller 112 (step S806).

[0269] FIG. 36 is a graph for explaining the speed changes of the feed roller 112, the brake roller 113, and the transport roller 119 in the high-speed mode.

[0270] 36, graph G101 shows an example of the speed change of the feed roller 112, graph G102 shows an example of the speed change of the brake roller 113, and graph G103 shows an example of the speed change of the conveyance roller 119. The horizontal axis of each of graphs G101 to G103 represents time, and the vertical axis represents speed. Graphs G14 and G15 show changes in the signal values ​​of the fifth medium sensor 118 and the sixth medium sensor 121, which change in the same way as graphs G14 and G15 shown in FIG. 10. Times T1 to T6 represent times similar to times T1 to T6 shown in FIG. 10.

[0271] As shown by a solid line L10 in graph G101, at time T2, the control unit 151 stops the feed roller 112. Alternatively, as shown by a dotted line D10 in graph G101, the control unit 151 decelerates the feed roller 112 at time T2.

[0272] Next, the control unit 151 detects the thickness of the medium being conveyed in the same manner as in step S307 of FIG. 18 (step S807).

[0273] Next, the control unit 151 sets and changes the speed of the transport roller 119 based on the detected thickness of the medium (step S808). The speed of the transport roller 119 is set within a range equal to or greater than the initial speed W1 and equal to or less than the final speed W3a. In particular, the control unit 151 sets the rotation speed of the transport roller 119 so that the speed of the transport roller 119 is equal to or greater than the speed of the feed roller 112. This allows the control unit 151 to prevent the medium from being pushed by the feed roller 112 and bending between the feed roller 112 and the transport roller 119, causing a medium jam.

[0274] The speed of the transport roller 119 is set to be higher as the thickness of the medium decreases and lower as the thickness of the medium increases. Alternatively, the speed of the transport roller 119 may be set to be higher as the thickness of the medium increases and lower as the thickness of the medium decreases. The medium transport device 100 stores in advance in the storage device 140 a table that defines the relationship between the thickness of the medium and the speed of the transport roller 119. The control unit 151 references the table stored in the storage device 140 and identifies the speed that corresponds to the detected thickness.

[0275] In this way, the control unit 151 sets the speed of the conveying roller 119 based on the detected thickness of the medium. This allows the control unit 151 to convey the medium at an appropriate speed according to the thickness of the medium.

[0276] As shown in graph G103 of FIG. 36, the control unit 151 changes the speed of the conveying roller 119 to the speed set in step S808 while the feeding roller 112 is stopped or decelerated.

[0277] Next, the control unit 151 restarts the rotation of the feed roller 112 and changes the speed of the brake roller 113. Alternatively, the control unit 151 changes the speeds of the feed roller 112 and the brake roller 113 (step S809).

[0278] 36, after setting the speed of the feed roller 112 to the final speed V3a, the control unit 151 resumes rotation of the feed roller 112 or changes the speed of the feed roller 112 to increase it to the final speed V3a. Also, as shown in graph G102, the control unit 151 changes the speed of the brake roller 113 to increase it to the final speed U3a.

[0279] In this way, when the leading edge of the medium passes the fifth medium sensor 118, the control unit 151 temporarily stops or decelerates the feed roller 112, detects the thickness of the medium, and sets the rotation speed of the transport roller 119 based on the thickness of the medium. The control unit 151 then resumes the rotation of the feed roller 112 or accelerates the feed roller 112. If the thickness of the medium is detected while the medium is being fed, a detection error may occur due to shaking of the medium, etc. The control unit 151 can detect the thickness of the medium more accurately by detecting the thickness of the medium with the feed roller 112 temporarily stopped or decelerated.

[0280] On the other hand, after waiting until the leading edge of the medium passes the position of fifth medium sensor 118 in step S821, control unit 151 controls first motor 131 to temporarily stop feed roller 112 or to reduce the speed of feed roller 112 (step S822). Thereafter, the processes of steps S807 to S809 are executed, and control unit 151 detects the thickness of the next medium and sets the rotation speed of conveyance roller 119 based on the thickness of the medium, and then resumes rotation of feed roller 112 or accelerates feed roller 112.

[0281] 36, at time T5, the control unit 151 stops or decelerates the feed roller 112. Thereafter, as shown in graph G103, the control unit 151 changes the speed of the conveyance roller 119 to the speed newly set in step S808, and restarts or accelerates the rotation of the feed roller 112, as shown in graph G101.

[0282] As described above in detail, the media transport device is now able to better control the feeding of media even when changing the speed of the transport roller 119 based on the thickness of the media.

[0283] Note that even when the medium conveying device changes the speed of the conveying roller 119 based on the thickness of the medium, the brake roller 113 may be driven by either the first motor or the second motor. In this case, the control unit 151 matches the timing of changing the speed of the brake roller 113 with the timing of changing the speed of the feed roller 112 or the conveying roller 119. The control unit 151 may also change the speed of the feed roller 112 or the brake roller 113 by controlling the first electromagnetic clutch 133 or the second electromagnetic clutch 134. The medium conveying device may also have a driving force interruption mechanism, such as an electromagnetic clutch, between the conveying roller 119 and the second motor, and the control unit 151 may change the speed of the conveying roller 119 by controlling the driving force interruption mechanism.

[0284] 37 is a diagram showing a schematic configuration of a processing circuit 250 in a medium conveying device according to another embodiment. The processing circuit 250 is used in place of the processing circuit 150 of the medium conveying device 100, and executes medium reading processing and the like in place of the processing circuit 150. The processing circuit 250 includes a control circuit 251 and a determination circuit 252. Note that each of these components may be configured as an independent integrated circuit, microprocessor, firmware, or the like.

[0285] 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 135. The control circuit 251 also receives a first medium signal, a second medium signal, an ultrasonic signal, a fifth medium signal, and a sixth medium signal from the first medium sensor 111, the second medium sensor 114, the ultrasonic sensor 115, the fifth medium sensor 118, and the sixth medium sensor 121, respectively. The control circuit 251 also receives a determination result of the skew of the medium from the determination circuit 252. The control circuit 251 controls the first motor 131, the second motor 132, the third motor 336, the first electromagnetic clutch 133, and the second electromagnetic clutch 134 based on the received information, and also acquires an input image from the imaging device 122 and outputs it to the interface device 135.

[0286] The determination circuit 252 is an example of a determination unit, and has the same function as the determination unit 152. The determination circuit 252 receives a third medium signal, a fourth medium signal, and a fifth medium signal from the third medium sensor 116, the fourth medium sensor 117, and the fifth medium sensor 118, respectively. The determination circuit 252 determines whether or not medium skew has occurred based on the received signals, and outputs the determination result to the control circuit 251.

[0287] As described above in detail, the media transport device, when using the processing circuitry 250, is able to better control the feeding of the media.

[0288] Although preferred embodiments have been described above, the embodiments are not limited to these. For example, the medium conveying device 100 may have a thin paper conveying mode for conveying thin paper as a medium and a normal mode for conveying other media. In this case, the control unit 151 sets the rotation speed of the feed roller 112 so that the speed of the feed roller 112 in the normal mode is higher than the speed of the feed roller 112 in the thin paper conveying mode. This allows thin paper to be conveyed at a slower speed than other media, allowing the control unit 151 to prevent damage to the thin paper caused by conveyance.

[0289] Also, as in the above-described embodiments, the control unit 151 sets the rotational speed of the feed roller 112 and the rotational speed of the conveyance roller 119 in the normal mode and the thin paper conveyance mode so that the speed of the conveyance roller 119 is greater than the speed of the feed roller 112. This allows the control unit 151 to prevent the medium from being pushed by the feed roller 112 and bending between the feed roller 112 and the conveyance roller 119 in the normal mode and the thin paper conveyance mode, thereby preventing a medium jam from occurring. Furthermore, the control unit 151 sets the rotational speed of the feed roller 112 and the rotational speed of the conveyance roller 119 so that the ratio of the speed of the feed roller 112 to the speed of the conveyance roller 119 in the normal mode is smaller than the ratio of the speed of the feed roller 112 to the speed of the conveyance roller 119 in the thin paper conveyance mode. This brings the speed of the feed roller 112 closer to the speed of the conveyance roller 119 in the thin paper conveyance mode, allowing thin paper to be conveyed more stably.

[0290] The medium conveying device may also have a separation mode in which the medium is fed while being separated, and a non-separation mode in which the medium is fed without being separated. In this case, the control unit 151 executes the above-described medium reading processes when operating in the separation mode. On the other hand, when operating in the non-separation mode, the control unit 151 controls each motor so that the brake roller 113 rotates in the medium feeding direction or so that it rotates together with the feed roller 112. In this case, the control unit 151 controls the second electromagnetic clutch 134 to change the magnitude of the torque applied to the brake roller 113. This allows the control unit 151 to feed the medium appropriately in both the separation mode and the non-separation mode.

[0291] Furthermore, the medium transport device may not have high-speed, medium-speed, and low-speed modes, but may operate fixedly in the high-speed mode.

[0292] Furthermore, when determining whether to use fifth medium sensor 118, control unit 151 may use second medium sensor 114 instead of fifth medium sensor 118. That is, control unit 151 may execute each of the above-described processes that are executed when the leading or trailing edge of the medium passes the position of fifth medium sensor 118 when the leading or trailing edge of the medium passes the position of second medium sensor 114.

[0293] Furthermore, the size or thickness of the medium may not be detected using a sensor, but may be set by the user using the operation device 105 or an information processing device. Alternatively, the size or thickness of the medium may be identified from the medium type (paper, postcard, business card, etc.) set by the user using the operation device 105 or an information processing device. In this case, the medium conveying device stores in advance in the storage device 140 a table that defines the relationship between the medium type and the medium size or thickness. The control unit 151 refers to the table stored in the storage device 140 and identifies the size or thickness of the medium to be conveyed. The following additional notes are provided regarding the above-described embodiment. (Appendix 1) a mounting table on which the medium is placed; a feeding roller that separates and sequentially feeds the media placed on the placement table; a motor that drives the feed roller; a conveying roller that conveys the medium fed by the feeding roller; a sensor disposed between the feeding roller and the transport roller for detecting the medium; a control unit that controls the motor to rotate the feed roller at a constant speed when feeding a first medium among the media placed on the mounting table during a separation period from when the feed roller starts feeding the medium until the sensor detects the leading edge of the medium, and controls the motor to rotate the feed roller at a first speed and then at a second speed higher than the first speed when feeding a second or subsequent medium; A medium transport device comprising: (Appendix 2) The medium transport device described in Appendix 1, wherein the control unit controls the motor to continue rotating the feed roller while reducing the rotational speed of the feed roller when the leading edge of the medium passes the transport roller. (Appendix 3) 3. The medium conveying device according to claim 1, wherein the control unit reduces the rotation speed of the conveying roller when the trailing edge of the medium passes the sensor. (Appendix 4) an imaging unit disposed downstream of the transport roller in a medium transport direction and configured to capture an image of the medium transported by the transport roller; 4. The medium conveying device according to claim 1, wherein the control unit increases the rotation speed of the conveyance roller when the trailing edge of the medium passes an imaging position of the imaging unit. (Appendix 5) 5. The medium transport device according to claim 1, wherein the control unit increases the rotation speed of the feed roller when the trailing edge of the medium passes the transport roller. (Appendix 6) The control unit Detect the size of the media, A medium conveying device described in any one of Appendices 1 to 5, wherein the second speed when the size of the preceding medium is equal to or smaller than a size threshold is set to a speed lower than the second speed when the size of the preceding medium is larger than the size threshold. (Appendix 7) The control unit Detects the thickness of the media, A medium conveying device described in any one of Appendices 1 to 6, wherein the second speed when the thickness of the preceding medium is equal to or less than a thickness threshold is set to a speed lower than the second speed when the thickness of the preceding medium is greater than the thickness threshold. (Appendix 8) a discharge roller for discharging the medium conveyed by the conveyance roller; The control unit Detect the size of the media, A medium conveying device described in any one of Appendices 1 to 7, wherein the rotation speed of the discharge roller when the medium size is larger than a first size threshold is set to a speed lower than the rotation speed of the discharge roller when the medium size is equal to or smaller than the first size threshold. (Appendix 9) a discharge roller for discharging the medium conveyed by the conveyance roller; The control unit Detect the size of the media, A medium conveying device described in any one of Appendices 1 to 7, wherein the rotation speed of the discharge roller when the medium size is smaller than a second size threshold is set to a speed lower than the rotation speed of the discharge roller when the medium size is equal to or greater than the second size threshold. (Appendix 10) The control unit Detect the size of the media, increasing the rotational speed of the feed roller after the sensor detects the leading edge of the medium; A medium conveying device described in any one of Appendices 1 to 9, wherein the timing for increasing the rotational speed of the feed roller when the size of the preceding medium is larger than a first size threshold is delayed from the timing for increasing the rotational speed of the feed roller when the size of the preceding medium is equal to or smaller than the first size threshold. (Appendix 11) The control unit Detect the size of the media, stopping the feeding roller when the leading edge of the medium passes the conveying roller, and restarting feeding by the feeding roller after the trailing edge of the medium passes a predetermined position; A media conveying device as described in any one of appendices 1 to 10, wherein the timing at which the feeding roller resumes feeding when the size of the medium whose trailing end has passed the specified position or the medium preceding the medium is larger than a first size threshold is delayed from the timing at which the feeding roller resumes feeding when the size of the medium whose trailing end has passed the specified position or the medium preceding the medium is equal to or smaller than the first size threshold. (Appendix 12) The control unit Detects the thickness of the media, 12. The medium conveying device according to any one of claims 1 to 11, wherein the rotation speed of the conveying roller is set based on the thickness of the medium. (Appendix 13) The media conveying device described in Appendix 12, wherein the control unit temporarily stops or slows down the feed roller when the leading edge of the medium passes the sensor, detects the thickness of the medium, and sets the rotation speed of the conveying roller, and then resumes rotation of the feed roller or accelerates the feed roller. (Appendix 14) 14. The medium transport device according to any one of claims 1 to 13, wherein the control unit sets the rotation speed of the transport roller so that the surface movement speed of the transport roller is equal to or greater than the surface movement speed of the feed roller. (Appendix 15) the medium transport device has a normal mode and a thin paper transport mode; The control unit sets the rotational speed of the feed roller and the rotational speed of the conveying roller so that the ratio of the surface movement speed of the feed roller to the surface movement speed of the conveying roller in the normal mode is smaller than the ratio of the surface movement speed of the feed roller to the surface movement speed of the conveying roller in the thin paper conveying mode, and the surface movement speed of the feed roller in the normal mode is greater than the surface movement speed of the feed roller in the thin paper conveying mode. (Appendix 16) A medium conveying device described in any one of Appendices 1 to 15, wherein the control unit temporarily stops or slows down the feed roller if the time from when the trailing end of the preceding medium passes the first position to when the leading end of the following medium passes the second position is less than a predetermined time. (Appendix 17) A medium conveying device as described in any one of appendices 1 to 16, wherein the control unit temporarily stops or decelerates the feed roller when the leading edge of the medium following the leading medium passes the sensor, and determines the timing to resume rotation of the feed roller or the timing to accelerate the feed roller based on the time from when the trailing edge of the leading medium passes the first position to when the leading edge of the following medium passes the second position. [Explanation of symbols]

[0294] 100 medium conveying device, 103 placing table, 112 feeding roller, 113 brake roller, 114 second medium sensor, 118 fifth medium sensor, 119, 219 conveying roller, 122 imaging device, 123, 223 discharge roller, 131, 231 first motor, 132, 232 second motor, 133 first electromagnetic clutch, 134 second electromagnetic clutch, 151 control unit, 152 determination unit, 336 third motor

Claims

1. a mounting table on which the medium is placed; a feeding roller that separates and sequentially feeds the media placed on the placement table; a conveying roller that conveys the medium fed by the feeding roller; a motor that drives the feed roller; a sensor that is disposed downstream of the feed roller in the medium transport direction and detects the medium; a control unit that controls the motor to rotate the feed roller at a constant predetermined speed when feeding a first medium among the media placed on the mounting table during a separation period from when the feed roller starts feeding the medium until the sensor detects the leading edge of the medium, and controls the motor to rotate the feed roller at a first speed higher than the predetermined speed and then at a second speed higher than the first speed when feeding a second or subsequent medium, the control unit controls the motor to continue rotating the feed roller while reducing the rotation speed of the feed roller when the leading edge of the medium passes the transport roller. A medium transport device comprising:

2. a mounting table on which the medium is placed; a feeding roller that separates and sequentially feeds the media placed on the placement table; a motor that drives the feed roller; a sensor that is disposed downstream of the feed roller in the medium transport direction and detects the medium; a control unit that controls the motor to rotate the feed roller at a constant predetermined speed when feeding a first medium among the media placed on the mounting table during a separation period from when the feed roller starts feeding the medium until the sensor detects the leading edge of the medium, and controls the motor to rotate the feed roller at a first speed higher than the predetermined speed and then at a second speed higher than the first speed when feeding a second or subsequent medium, the control unit sets the second speed when the size of the preceding medium is equal to or smaller than a size threshold to a speed lower than the second speed when the size of the preceding medium is larger than the size threshold. A medium transport device characterized by:

3. A medium transport device having a normal mode and a thin paper transport mode, a mounting table on which the medium is placed; a feeding roller that separates and sequentially feeds the media placed on the placement table; a conveying roller that conveys the medium fed by the feeding roller; a motor that drives the feed roller; a sensor that is disposed downstream of the feed roller in the medium transport direction and detects the medium; a control unit that controls the motor to rotate the feed roller at a constant predetermined speed when feeding a first medium among the media placed on the mounting table during a separation period from when the feed roller starts feeding the medium until the sensor detects the leading edge of the medium, and controls the motor to rotate the feed roller at a first speed higher than the predetermined speed and then at a second speed higher than the first speed when feeding a second or subsequent medium, the control unit sets the rotation speed of the feed roller and the rotation speed of the conveying roller so that a ratio of the surface movement speed of the feed roller to the surface movement speed of the conveying roller in the normal mode is smaller than a ratio of the surface movement speed of the feed roller to the surface movement speed of the conveying roller in the thin paper conveying mode, and the surface movement speed of the feed roller in the normal mode is larger than the surface movement speed of the feed roller in the thin paper conveying mode. A medium transport device characterized by:

4. A control program for a medium transport device having a mounting table on which a medium is placed, a feed roller that separates and sequentially feeds the media placed on the mounting table, a motor that drives the feed roller, and a sensor that is disposed downstream of the feed roller in a medium transport direction and detects the medium, the program comprising: During a separation period from when the feeding roller starts feeding the medium until the sensor detects the leading edge of the medium, when feeding the first medium among the media placed on the mounting table, the motor is controlled to rotate the feeding roller at a constant predetermined speed, and when feeding the second or subsequent medium, the motor is controlled to rotate the feeding roller at a first speed higher than the predetermined speed and then at a second speed higher than the first speed. a control program for causing the medium transport device to execute the above steps;

Images