Media transport 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 conveyance device, a control method, and a control program, and more particularly, to a medium conveyance device, a control method, and a control program that separate and sequentially feed media.

Background Art

[0002] In a medium conveyance device such as a scanner that sequentially feeds and images a plurality of media while separating them, it is required to further reduce the time required for feeding the media. On the other hand, when the free capacity of the storage device that stores the images of the media imaged by the medium conveyance device is insufficient, or when the distance between the continuously fed media is short, etc., it is necessary to temporarily stop the feeding of the media. In such cases, it is required to appropriately control the stop and restart of the feeding of the media in the medium conveyance device.

[0003] When starting the feeding of a subsequent sheet by a feeding roller after the arrival of the rear end of the preceding sheet is detected by a resist post sensor, a sheet feeding device that controls the feeding roller at a low speed is disclosed (see Patent Document 1). This sheet feeding device controls the feeding roller at a high speed when the leading end of the subsequent sheet exceeds the nip position between the feeding roller and the separating roller.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] In a medium conveyance device, it is required to better control the feeding of the medium.

[0006] An object of the medium conveyance device, the control method, and the control program is to enable better control of the feeding of the medium.

[0007] A media transport device according to one aspect of the embodiment includes a mounting table for mounting a media, a feeding roller for separating and sequentially feeding the media mounted on the mounting table, and a transport roller for transporting the media fed by the feeding roller , a feeder a motor for driving the feeding roller, A sensor that is disposed downstream of the feed roller in the medium conveyance direction and detects the medium, and during the separation period from the start of feeding the medium by the feed roller until the sensor detects the leading edge of the medium, when feeding the first medium among the media placed on the placement table, the motor is controlled to rotate the feed roller at a constant predetermined speed, and when feeding the second and subsequent media, the motor is controlled 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. 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 through the conveyance roller. .

[0008] Further, a medium conveyance device according to an aspect of the embodiment includes a placement table for placing a medium, a feed roller for separating and sequentially feeding the media placed on the placement table, a motor for driving the feed roller, a sensor that is disposed downstream of the feed roller in the medium conveyance direction and detects the medium, and during the separation period from the start of feeding the medium by the feed roller until the sensor detects the leading edge of the medium, when feeding the first medium among the media placed on the placement table, the motor is controlled to rotate the feed roller at a constant predetermined speed, and when feeding the second and subsequent media, the motor is controlled 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. The control unit sets the second speed when the size of the preceding medium is less than or equal to the size threshold to a speed lower than the second speed when the size of the preceding medium is greater than the size threshold.

[0009] Also, a medium conveyance device according to an aspect of the embodiment is a medium conveyance device having a normal mode and a thin paper conveyance mode, and includes a mounting table on which a medium is placed, a feeding roller that separates and sequentially feeds the medium placed on the mounting table, a conveyance roller that conveys the medium fed by the feeding roller, a motor that drives the feeding roller, a sensor that is disposed downstream of the feeding roller in the medium conveyance direction and detects the medium, and during a separation period from the start of feeding of the medium by the feeding roller until the sensor detects the leading end 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 and subsequent media, 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. The control unit has a control unit that sets the rotational speed of the feeding roller and the rotational speed of the conveyance roller such that the ratio of the surface movement speed of the feeding roller to the surface movement speed of the conveyance roller in the normal mode is smaller than the ratio of the surface movement speed of the feeding roller to the surface movement speed of the conveyance roller in the thin paper conveyance mode, and the surface movement speed of the feeding roller in the normal mode is higher than the surface movement speed of the feeding roller in the thin paper conveyance mode. Also, a control program according to an aspect of the embodiment causes a medium conveyance device having a mounting table on which a medium is placed, a feeding roller that separates and sequentially feeds the medium placed on the mounting table, a motor that drives the feeding roller, and a sensor that is disposed downstream of the roller in the medium conveyance direction and detects the medium to execute, during a separation period from the start of feeding of the medium by the feeding roller until the sensor detects the leading end of the medium, controlling the motor to rotate the feeding roller at a constant predetermined speed when feeding the first medium among the media placed on the mounting table, and controlling the motor 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 when feeding the second and subsequent media.

[0010] According to this embodiment, the media transport device, the control method, and the control program can control the feeding of the media better.

[0011] The object and effect of the present invention will be recognized and obtained by using the components 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 intended to limit the present invention described in the claims.

Brief Description of the Drawings

[0012]

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Embodiments for Carrying Out the Invention

[0013] Hereinafter, a medium conveyance device, a control method, and a control program according to one aspect of the present disclosure will be described with reference to the drawings. However, it should be noted that the technical scope of the present invention is not limited to those embodiments, and extends to the invention described in the claims and its equivalents.

[0014] FIG. 1 is a perspective view showing a media conveyance device 100 configured as an image scanner. The media conveyance device 100 conveys and images a medium that is an original document. The medium may be paper, cardboard, a card, a booklet, a passport, or the like. The media conveyance device 100 may also be a facsimile machine, a copier, a printer multifunction peripheral (MFP), or the like. Note that the conveyed medium may not be an original document but a printing object or the like, and the media conveyance device 100 may be a printer or the like.

[0015] The media conveyance device 100 includes a lower housing 101, an upper housing 102, a placement table 103, a discharge table 104, an operation device 105, a display device 106, and the like.

[0016] The upper housing 102 is disposed at a position covering the upper surface of the media conveyance device 100 and is engaged with the lower housing 101 by a hinge so as to be openable and closable when the medium is jammed or when cleaning inside the media conveyance device 100.

[0017] The placement table 103 is engaged with the lower housing 101 and places the medium to be fed and conveyed. The discharge table 104 is engaged with the upper housing 102 and places the discharged medium. Note that the discharge table 104 may be engaged with the lower housing 101.

[0018] The operation device 105 has an input device such as a button and an interface circuit that acquires a signal from the input device, receives an input operation by a user, and outputs an operation signal corresponding to the user's input operation. The display device 106 has a display including liquid crystal, organic EL (Electro-Luminescence), or the like and an interface circuit that outputs image data to the display, and displays the image data on the display.

[0019] FIG. 2 is a diagram for explaining a conveyance path inside the media conveyance device 100.

[0020] The conveyance path inside the media conveyance device 100 includes a first media sensor 111, a feeding 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 conveyance roller 119, a first opposing roller 120, a sixth media sensor 121, an imaging device 122, a discharge roller 123, a second opposing roller 124, and the like.

[0021] Note that the number of each of the feeding roller 112, the brake roller 113, the conveyance roller 119, the first opposing roller 120, the discharge roller 123, and / or the second opposing roller 124 is not limited to one, and a plurality may be provided. In that case, the plurality of feeding rollers 112, brake rollers 113, conveyance rollers 119, first opposing rollers 120, discharge rollers 123, and / or second opposing rollers 124 are arranged side by side at intervals in the width direction orthogonal to the media conveyance direction A1.

[0022] The upper surface of the lower housing 101 forms a lower guide 101a of the media conveyance path, and the lower surface of the upper housing 102 forms an upper guide 102a of the media conveyance path. In FIG. 2, the arrow A1 indicates the media conveyance direction. Hereinafter, "upstream" refers to the upstream in the media conveyance direction A1, and "downstream" refers to the downstream in the media conveyance direction A1.

[0023] The first media sensor 111 is disposed upstream of the feeding roller 112 and the brake roller 113. The first media sensor 111 has a contact detection sensor and detects whether a media is placed on the mounting table 103. The first media sensor 111 generates and outputs a first media signal whose signal value changes between a state where a media is placed on the mounting table 103 and a state where no media is placed. Note that the first media sensor 111 is not limited to a contact detection sensor, and any other sensor capable of detecting the presence or absence of a media, such as an optical detection sensor, may be used as the first media sensor 111.

[0024] The feeding roller 112 is provided on the lower housing 101 and sequentially separates and feeds the medium placed on the mounting table 103 from below. The brake roller 113 is provided on the upper housing 102, is arranged to face the feeding roller 112, and rotates in the direction opposite to the medium feeding direction. Incidentally, the feeding roller 112 may be provided on the upper housing 102, the brake roller 113 may be provided on the lower housing 101, and the feeding roller 112 may sequentially feed the medium placed on the mounting table 103 from above.

[0025] The second medium sensor 114 is an example of the second sensor, is arranged downstream of the feeding roller 112 and upstream of the conveying roller 119, and detects the medium conveyed to that position. In particular, the second medium sensor 114 is arranged between the feeding roller 112 and the fifth medium sensor 118 in the medium conveying direction A1, in the vicinity of the nip region of the feeding roller 112 and the brake roller 113. The second medium sensor 114 includes a light emitter and a light receiver provided on one side with respect to the medium conveying path, and a light guide tube provided at a position facing the light emitter and the light receiver with the medium conveying path interposed therebetween. The light emitter is an LED (Light Emitting Diode) or the like and irradiates light toward the medium conveying path. On the other hand, the light receiver is a photodiode or the like and receives the light irradiated by the light emitter and guided by the light guide tube. When a medium exists at a position facing the second medium sensor 114, the light irradiated from the light emitter is blocked by the medium, so the light receiver does not detect the light irradiated from the light emitter. The second medium sensor 114 generates and outputs a second medium signal whose signal value changes between a state where a medium exists and a state where no medium exists at the position of the second medium sensor 114 based on the intensity of the light received by the light receiver.

[0026] The ultrasonic sensor 115 is disposed downstream of the feeding 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 disposed opposite to each other across the conveyance path in the vicinity of the conveyance path of the medium. The ultrasonic transmitter 115a transmits ultrasonic waves. On the other hand, the ultrasonic receiver 115b receives the ultrasonic waves transmitted 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 a plurality of media are conveyed overlapping each other, the ultrasonic waves transmitted through the medium are attenuated in the air layer between the overlapping media. Therefore, the medium conveying device 100 can detect the double feeding of the medium based on the ultrasonic signal. Further, the ultrasonic waves transmitted through the medium are also attenuated by the medium itself, and the greater the thickness of the medium through which the ultrasonic waves are transmitted, the greater the attenuation amount. Therefore, the medium conveying device 100 can detect the thickness of the conveyed medium based on the ultrasonic signal.

[0027] The fifth medium sensor 118 is an example of a sensor, and is disposed downstream of the feeding roller 112 and upstream of the conveying roller 119, and detects the medium conveyed to that position. That is, the fifth medium sensor 118 is disposed between the feeding roller 112 and the conveying roller 119. The fifth medium sensor 118 includes a light emitter and a light receiver provided on one side with respect to the medium conveyance path, and a light guide tube provided at a position facing the light emitter and the light receiver across the medium conveyance path. The light emitter is an LED or the like, and irradiates light toward the medium conveyance path. On the other hand, the light receiver is a photodiode or the like, and receives the light irradiated by the light emitter and guided by the light guide tube. The fifth medium sensor 118 generates and outputs a fifth medium signal whose signal value changes between a state where a medium exists and a state where no medium exists at the position of the fifth medium sensor 118 based on the intensity of the light received by the light receiver.

[0028] The conveying roller 119 and the first opposing roller 120 are arranged to face each other on the downstream side of the feeding roller 112, and convey the medium fed by the feeding roller 112 and the brake roller 113 to the imaging device 122. The conveying roller 119 is provided on the upper housing 102, and the first opposing roller 120 is provided on the lower housing 101, below the conveying roller 119.

[0029] The sixth medium sensor 121 is arranged on the downstream side of the conveying roller 119 and on the upstream side of the imaging device 122, and detects the medium conveyed to that position. The sixth medium sensor 121 includes a light emitter and a light receiver provided on one side of the medium conveyance path, and a light guide tube provided at a position facing the light emitter and the light receiver with the medium conveyance path therebetween. The light emitter is, for example, an LED, and irradiates light toward the medium conveyance path. On the other hand, the light receiver is, for example, a photodiode, and receives the light irradiated by the light emitter and guided by the light guide tube. The sixth medium sensor 121 generates and outputs a sixth medium signal whose signal value changes between a state where a medium exists and a state where no medium exists at the position of the sixth medium sensor 121 based on the intensity of the light received by the light receiver.

[0030] The imaging device 122 is an example of an imaging unit, is arranged on the downstream side of the conveying roller 119, and images the medium conveyed by the conveying roller 119. The imaging device 122 includes a first imaging device 122a and a second imaging device 122b arranged to face each other with the medium conveyance path therebetween. The first imaging device 122a has a line sensor by a CIS (Contact Image Sensor) of an equi-magnification optical system type having an imaging element by CMOS (Complementary Metal Oxide Semiconductor) 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 the electrical signal output from the imaging element and performs analog / digital (A / D) conversion. The first imaging device 122a images the surface of the conveyed medium and generates and outputs an input image according to the control from a processing circuit described later.

[0031] Similarly, the second imaging device 122b has a line sensor using a CIS of an equal magnification optical system type having an imaging element made of CMOS arranged linearly 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 an electrical signal output from the imaging element and performs analog / digital (A / D) conversion. The second imaging device 122b captures an image of the back surface of the conveyed medium in accordance with control from a processing circuit described later, generates an input image, and outputs it.

[0032] Note that the medium conveyance device 100 may arrange only one of the first imaging device 122a and the second imaging device 122b and read only one side of the medium. Also, instead of the line sensor using a CIS of an equal magnification optical system type including an imaging element made of CMOS, a line sensor using a CIS of an equal magnification optical system type including an imaging element made of a CCD (Charge Coupled Device) may be used. Further, a line sensor of a reduced optical system type including an imaging element made of CMOS or CCD may be used.

[0033] The discharge roller 123 and the second opposing roller 124 are arranged to face each other on the downstream side of the imaging device 122, discharge the medium conveyed by the conveyance roller 119 and the first opposing roller 120 and imaged by the imaging device 122 to the discharge table 104. The discharge roller 123 is provided on the upper housing 102, and the second opposing roller 124 is provided on the lower housing 101, below the discharge roller 123.

[0034] The medium placed on the placement table 103 is conveyed in the medium conveyance direction A1 between the lower guide 101a and the upper guide 102a by the feeding roller 112 rotating in the direction of arrow A2 in FIG. 2, that is, the medium feeding direction. The brake roller 113 rotates in the direction of arrow A3, that is, the direction opposite to the medium feeding direction, during medium conveyance. By the action of the feeding roller 112 and the brake roller 113, when a plurality of media are placed on the placement table 103, only the medium in contact with the feeding roller 112 among the media placed on the placement table 103 is separated. Thereby, the conveyance of media other than the separated medium is restricted (prevention of double feeding).

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

[0036] FIG. 3 is a schematic diagram for explaining the drive sources of the feed roller 112, the brake roller 113, the conveying roller 119, the first opposing roller 120, the discharge roller 123 and / or the second opposing roller 124.

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

[0038] The first motor 131 is an example of a motor, is provided in the lower housing 101, is connected to the feed roller 112 via a first transmission mechanism 131a, and drives the feed roller 112. The first motor 131 generates a driving force for driving the feed roller 112 according to a control signal from the processing circuit. The first transmission mechanism 131a includes one or a plurality of 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. Thereby, the first motor 131 rotates the 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 roller 119, the discharging roller 123, and the brake roller 113 via a second transmission mechanism 132a, and drives the conveying roller 119, the discharging roller 123, and the brake roller 113. The second motor 132 generates a driving force for driving the conveying roller 119, the discharging roller 123, and the brake roller 113 according to a control signal 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 discharging 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 conveying roller 119 and / or the shaft 123a of the discharging roller 123 and the shaft 113a of the brake roller 113 to make the rotation directions and rotation speeds of the respective rollers different. The second transmission mechanism 132a transmits the driving force generated by the second motor 132 to the conveying roller 119, the discharging roller 123, and the brake roller 113. Thereby, the second motor 132 rotates the conveying roller 119, the discharging roller 123, and the brake roller 113 to feed, convey, and discharge the medium to the conveying roller 119, the discharging roller 123, and the brake roller 113. The second motor 132 is an example of a driving source of the brake roller 113.

[0040] The first opposing roller 120 is a driven roller that rotates in a driven manner with respect to the conveying roller 119, and the second opposing roller 124 is a driven roller that rotates in a driven manner with respect to the discharging roller 123. Note that the first opposing roller 120 and / or the second opposing roller 124 may be provided so as to be driven by the driving force from the second motor 132. In that case, one or more gears are further provided between the shaft 119a of the conveying roller 119 and the shaft 120a of the first opposing roller 120, and / or between the shaft 123a of the discharging 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] FIG. 4 and FIG. 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 viewed from above, and FIG. 5 is a schematic diagram of the upper guide 102a of the upper housing 102 viewed from below.

[0042] As shown in FIGS. 4 and 5, the third medium sensor 116 and the fourth medium sensor 117 are arranged 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 arranged between the second medium sensor 114 and the fifth medium sensor 118 in the medium transport direction A1. Note that the third medium sensor 116 and the fourth medium sensor 117 may be arranged at substantially the same position as the fifth medium sensor 118 in the medium transport direction A1. Also, the third medium sensor 116 and the fourth medium sensor 117 are arranged side by side with a gap in the width direction A8 orthogonal to the medium transport direction.

[0043] The third medium sensor 116 includes a light emitter and a light receiver provided on one side with respect to the medium transport path, and a light guide tube provided at a position facing the light emitter and the light receiver with the medium transport path therebetween. The light emitter is an LED or the like and irradiates light toward the medium transport path. On the other hand, the light receiver is a photodiode or the like and receives the light irradiated by the light emitter and guided by the light guide tube. The third medium sensor 116 generates and outputs a third medium signal whose signal value changes between a state where a medium exists and a state where no medium exists at the position of the third medium sensor 116 based on the intensity of the light received by the light receiver.

[0044] The fourth media sensor 117 includes a light emitter and a light receiver provided on one side with respect to the media conveyance path, and a light guide pipe provided at a position facing the light emitter and the light receiver with the media conveyance path therebetween. The light emitter is an LED or the like, and irradiates light toward the media conveyance path. On the other hand, the light receiver is a photodiode or the like, and receives the light irradiated by the light emitter and guided by the light guide pipe. The fourth media sensor 117 generates and outputs a fourth media signal whose signal value changes between a state where a media exists and a state where no media exists at the position of the fourth media sensor 117 based on the intensity of the light received by the light receiver.

[0045] Note that in the second media sensor 114, the third media sensor 116, the fourth media sensor 117, the fifth media sensor 118, and / or the sixth media sensor 121, a reflection member such as a mirror may be used instead of the light guide pipe. Also, in the second media sensor 114, the third media sensor 116, the fourth media sensor 117, the fifth media sensor 118, and / or the sixth media sensor 121, the light emitter and the light receiver may be provided to face each other with the media conveyance path therebetween. Further, the second media sensor 114, the third media sensor 116, the fourth media sensor 117, the fifth media sensor 118, and / or the sixth media sensor 121 may detect the presence of the media by a contact detection sensor or the like that passes a predetermined current when the media is in contact or not in contact.

[0046] Also, as shown in FIG. 4, the media conveyance device 100 has a first electromagnetic clutch 133. The first electromagnetic clutch 133 is an example of a blocking mechanism, and is provided on the shaft 112a of the feed roller 112, that is, 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 block the driving force from the first motor 131 to the feed roller 112 by a control signal from the processing circuit.

[0047] Also, as shown in FIG. 5, the medium transport device 100 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, that is, on the 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 the processing circuit.

[0048] FIG. 6 is a block diagram showing a schematic configuration of the medium transport device 100.

[0049] In addition to the above-described configuration, 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, for example, and is electrically connected to an information processing device (for example, a personal computer, a mobile information terminal, etc.) (not shown) to transmit and receive an input image and various types of information. Further, instead of the interface device 135, a communication unit having an antenna for transmitting and receiving radio signals and a wireless communication interface device for transmitting and receiving signals through a wireless communication line according to a predetermined communication protocol may be used. The predetermined communication protocol is, for example, a wireless LAN (Local Area Network). The communication unit may have a wired communication interface device for transmitting and receiving signals through a wired communication line according to 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 an optical disk. Further, the storage device 140 stores computer programs, databases, tables, etc. used for various processes of the medium conveyance device 100. The computer program may be installed in 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 the storage device 140 in advance. The processing circuit is, for example, a CPU (Central Processing Unit). As the processing circuit 150, a DSP (digital signal processor), an LSI (large scale integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or the like may be used.

[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, the storage device 140, etc., and controls these respective units. The processing circuit 150 performs drive control of the first motor 131, imaging control of the imaging device 122, etc. based on each medium signal received from each sensor, acquires an input image from the imaging device 122, and transmits it 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.

[0055] As shown in FIG. 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 operating on a processor. The processing circuit 150 reads each program stored in the storage device 140 and operates according to each read program. Thereby, the processing circuit 150 functions as a control unit 151 and a determination unit 152.

[0056] FIGS. 8 and 9 are flowcharts showing examples of operations of the medium reading process of the medium conveyance device 100.

[0057] Hereinafter, an example of the operation of the medium reading process of the medium conveyance device 100 will be described with reference to the flowcharts shown in FIGS. 8 and 9. Note that the flow of the operation described below is mainly executed by the processing circuit 150 in cooperation with each element of the medium conveyance device 100 based on a program stored in the storage device 140 in advance.

[0058] First, the control unit 151 waits until an instruction to read a medium is input by the user using the operation device 105 or the information processing device, and a control signal instructing the reading of the medium is received from the operation device 105 or the interface device 135 (step S101).

[0059] Next, the control unit 151 acquires a first medium signal from the first medium sensor 111, and determines whether or not a medium is placed on the mounting table 103 based on the acquired first medium signal (step S102). If no medium is placed on the mounting table 103, the control unit 151 ends the series of steps.

[0060] On the other hand, when a medium is placed on the mounting table 103, the control unit 151 sets the surface movement speeds of the feeding roller 112, the brake roller 113, the conveying roller 119, the first opposing roller 120, the discharging 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 contacts the medium moves. That is, the surface movement speeds of the feeding roller 112, the conveying roller 119, the first opposing roller 120, the discharging roller 123, and / or the second opposing roller 124 are the conveying speeds of the medium by the feeding roller 112, the conveying roller 119, and the discharging roller 123. The surface movement speed of the brake roller 113 is the speed at which the surface of the brake roller 113 that contacts the medium moves in a direction opposite to the medium feeding direction. Hereinafter, the surface movement speed of each roller may be simply referred to as speed.

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

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

[0063] In FIGS. 10 to 12, graphs G11, G21, and G31 show the speed changes of the feeding roller 112, graphs G12, G22, and G32 show the speed changes of the brake roller 113, and graphs G13, G23, and G33 show the speed changes of the conveying roller 119. Since the speeds of the first opposing roller 120, the discharging roller 123, and the second opposing roller 124 change in the same manner as the speed of the conveying roller 119, hereinafter, the speed changes of the conveying roller 119 will be described as a representative. The horizontal axes of the graphs G11 to G13, G21 to G23, and G31 to G33 indicate time, and the vertical axes indicate speed.

[0064] On the one hand, graph G14 shows the change in the signal value of the fifth medium sensor 118, and graph G15 shows the change in the signal value of the sixth medium sensor 121. The horizontal axis of each of graphs G14 and G15 indicates time, and the vertical axis indicates the signal value. In the present embodiment, when there is no medium at the position of each sensor, the signal value of the corresponding signal becomes L, and when there is a medium at the position of each sensor, the signal value of the corresponding signal becomes H.

[0065] In FIGS. 10 to 12, time T1 indicates the start time of medium feeding. As shown in FIGS. 10 to 12, regardless of whether the conveyance mode is set to the high-speed mode, the medium-speed mode, or the low-speed mode, at the start of medium feeding, the control unit 151 sets the speed of the feeding roller 112 to the initial speed V1. Further, when the conveyance mode is set to the high-speed mode, the control unit 151 sets the speed of the brake roller 113 to the initial speed U1 and sets the speed of the conveyance roller 119 to the initial speed W1. The initial speed U1 of the brake roller 113 is set to a speed higher than 1 / 2 of the initial speed V1 of the feeding roller 112. Further, the initial speed U1 of the brake roller 113 may be set to a speed lower than the initial speed V1 of the feeding roller 112.

[0066] On the other hand, when the conveyance mode is set to the medium-speed mode, the control unit 151 sets the speed of the brake roller 113 to the final speed U3b and sets the speed of the conveyance roller 119 to the 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 described later. The final speed W3b of the conveyance roller 119 is set to a speed lower than the final speed W3a of the conveyance roller 119 in the high-speed mode described later. Further, when the conveyance mode is set to the low-speed mode, the control unit 151 sets the speed of the brake roller 113 to the final speed U3c and sets the speed of the conveyance roller 119 to the 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 conveyance roller 119 is set to a speed lower than the final speed W3c of the conveyance roller 119 in the medium-speed mode.

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

[0068] The control unit 151 controls the first motor 131 and the second motor 132 so that each roller rotates at each set speed. As shown in FIGS. 10 to 12, after a predetermined ramp-up period has elapsed since the driving of each motor was started at time T1, each roller rotates at each set speed. Similarly, hereinafter, when the control unit 151 increases the speed of each roller, after a predetermined ramp-up period has elapsed since the driving of each motor was started, each roller rotates at each set speed. Also, similarly, when the control unit 151 reduces the speed of each roller, after a predetermined ramp-down period has elapsed since the driving of each motor was started, each roller rotates at each set speed.

[0069] Next, the control unit 151 waits until the leading end of the conveyed medium passes the position of the fifth medium sensor 118 (step S105). The control unit 151 periodically acquires a fifth medium signal from the fifth medium sensor 118, and determines that the leading end of the medium has passed the position of the fifth medium sensor 118 when the signal value of the fifth medium signal changes from a value indicating the absence of the medium to a value indicating the presence of the medium.

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

[0071] In FIGS. 10 to 12, time T2 indicates the time when the signal value of the fifth medium signal changes from L to H, that is, when the leading end of the medium passes the position of the fifth medium sensor 118. As shown in FIGS. 10 to 12, the speed of the feed roller 112 changed when the leading end of the medium passes the position of the fifth medium sensor 118 differs according to the conveyance 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, the control unit 151 waits until the leading end of the conveyed medium passes the position of the conveyance roller 119 (step S107). The control unit 151 periodically acquires a sixth medium signal from the sixth medium sensor 121, and determines that the leading end of the medium has passed the position of the sixth medium sensor 121 when the signal value of the sixth medium signal changes from a value indicating the absence of the medium to a value indicating the presence of the medium. The control unit 151 determines that the leading end of the medium has passed the position of the conveyance roller 119 when the leading end of the medium has passed the position of the sixth medium sensor 121.

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

[0076] In FIGS. 10 to 12, time T3 indicates the time when the signal value of the sixth medium signal changes from L to H, that is, the time when the leading end of the medium passes the position of the sixth medium sensor 121. As shown in FIGS. 10 to 12, after the leading end of the medium has passed the position of the sixth medium sensor 121, the control unit 151 stops the feed roller 112 (changes the speed to 0). Thereby, thereafter, the medium is conveyed by the conveyance roller 119, and the feed roller 112 is rotated by the conveyed medium. By stopping the feed roller 112, the control unit 151 can suppress the medium from being pushed by the feed roller 112 and being bent between the feed roller 112 and the conveyance roller 119, thereby preventing a jam of the medium.

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

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

[0079] Next, the control unit 151 determines whether there is any medium remaining on the mounting table 103 based on the first medium signal received from the first medium sensor 111 (step S111).

[0080] If there is any medium remaining on the mounting table 103, the control unit 151 sets the speed of the feed roller 112 for feeding the subsequent medium (step S112).

[0081] In FIGS. 10 to 12, the time T4 indicates the time when the signal value of the fifth medium signal changes from H to L, that is, when the rear end of the medium passes the position of the fifth medium sensor 118. As shown in FIGS. 10 to 12, when the rear end of the medium passes the position of the fifth medium sensor 118, the speed of the feed roller 112 set for feeding the subsequent medium varies according to the conveyance mode. When the conveyance mode is set to the high-speed mode or the medium-speed mode, the control unit 151 sets the speed of the feed roller 112 to the first intermediate speed V2a. The first intermediate speed V2a is an example of the 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-stage speed of the feed roller 112 when feeding the second and subsequent media. Note that the first intermediate speed V2a may be set to a speed substantially the same as the final speed V3c. On the other hand, when the conveyance 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 rotates the feed roller 112 by driving the first motor 131 to feed and convey the subsequent medium (step S113). The control unit 151 controls the first motor 131 so that the feed roller 112 rotates at the set speed.

[0083] Next, the control unit 151 waits until the leading edge of the subsequent medium passes the position of the second medium sensor 114 (step S114). The control unit 151 periodically acquires a second medium signal from the second medium sensor 114, and determines that the leading edge of the medium has passed the position of the second medium sensor 114 when the signal value of the second medium signal changes from a value indicating the absence of the medium to a value indicating the presence of the medium.

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

[0085] As shown in FIGS. 10 to 12, the speed of the feed roller 112 changed when the leading edge of the subsequent medium passes the position of the second medium sensor 114 differs according to the conveyance mode. When the conveyance mode is set to the high-speed mode, the control unit 151 changes the speed of the feed roller 112 to the 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 and subsequent media. Note that the second intermediate speed V2b may be set to a value substantially the same as the final speed V3b. On the other hand, when the conveyance 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. Further, when the conveyance mode is set to the low-speed mode, the control unit 151 does not change the speed of the feed roller 112.

[0086] Next, the control unit 151 waits until the rear end of the preceding medium passes through the imaging position of the imaging device 122 (step S116). The control unit 151 periodically acquires a sixth medium signal from the sixth medium sensor 121, and when the signal value of the sixth medium signal changes from a value indicating the presence of the medium to a value indicating the absence of the medium, it determines that the rear end of the preceding medium has passed through the position of the sixth medium sensor 121. The control unit 151 determines that the rear end of the preceding medium has passed through the imaging position when a first predetermined time has elapsed since the rear end of the preceding medium passed through the position of the 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 the sixth medium sensor 121 to the imaging position.

[0087] Next, the control unit 151 acquires an input image from the imaging device 122, stores the acquired input image in the storage device 140, 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, the control unit 151 waits until the front end of the subsequent medium passes through the position of the fifth medium sensor 118 in the same manner as in the process of step S105 (step S118).

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

[0090] In FIGS. 10 to 12, time T5 indicates the time when the signal value of the fifth medium signal changes from L to H, that is, when the front end of the subsequent medium passes through the position of the fifth medium sensor 118. As shown in FIGS. 10 to 12, when the conveyance mode is set to the high-speed mode, when the front end of the subsequent medium passes through the position of the fifth medium sensor 118, the control unit 151 changes the speed of the feed roller 112 to the final speed V3a. On the other hand, when the conveyance mode is set to the medium-speed mode or the low-speed mode, the control unit 151 does not change the speed of the feed roller 112.

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

[0092] On the other hand, in step S111, if no medium remains on the mounting table 103, the control unit 151 waits until the trailing end of the conveyed medium passes the imaging position of the imaging device 122 in the same manner as the process of step S116 (step S120).

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

[0094] Next, the control unit 151 waits until the trailing end of the conveyed medium passes the position of the discharge roller 123 (step S122). The control unit 151 determines that the trailing end of the medium has passed the position of the discharge roller 123 when a second predetermined time has elapsed since the trailing end 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 roller 123.

[0095] Next, the control unit 151 controls the second motor 132 to stop the brake roller 113, the conveyance 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, the control unit 151 may execute the processes after step S118 even if the transmission of the input image is not completed. In that case, in step S118, when the leading end of the subsequent medium passes the position of the fifth medium sensor 118, if the free capacity of the storage device 140 is less than a predetermined amount, the control unit 151 may temporarily stop the feeding of the subsequent medium. The control unit 151 controls the first motor 131 to stop the feeding roller 112 until the free capacity of the storage device 140 becomes equal to or more than the predetermined amount. Thereby, the medium transport device 100 can efficiently transport the medium while reliably transmitting the input image.

[0097] Also, in step S118, when the leading end of the subsequent medium passes the position of the fifth medium sensor 118, if the distance between the trailing end of the preceding medium and the leading end of the subsequent medium is short, the control unit 151 may temporarily stop the feeding of the subsequent medium. For example, the control unit 151 detects the time from when the trailing end of the preceding medium passes the position of the fifth medium sensor 118 or the sixth medium sensor 121 until the leading end of the subsequent 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 feeding roller 112 from when the trailing end of the preceding medium passes the position of the fifth medium sensor 118 or the sixth medium sensor 121 until the third predetermined time elapses. Thereby, the medium transport device 100 can efficiently transport the medium while suppressing the occurrence of medium jams.

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

[0099] FIGS. 13(a) and 13(b) are schematic diagrams of the feeding roller 112 and the brake roller 113 viewed from the side. FIG. 13(a) shows a state where the first medium M1 is being fed from the state where the medium group M is placed on the mounting table 103, and FIG. 13(b) shows a state where the second and subsequent media M2 are being fed from the state where the medium group M is placed on the mounting table 103.

[0100] As shown in FIG. 13(a), when a certain amount of the media group M is placed on the placement table 103, usually, the leading ends of the media group M are aligned by the user or by an alignment member (not shown). Therefore, the leading end of the lowermost first medium M1 has not reached the nip region between the feed roller 112 and the brake roller 113. In this case, the frictional force between the media is increased by the weight of the media group placed on the first medium M1. Due to this frictional force, the media group placed on the first medium M1 attempts to move downstream together with the first medium M1 to be fed and is pressed against the brake roller 113. If the speed of the feed roller 112 at this time is too high, the brake roller 113 may be lifted upward by the media group placed on the first medium M1, and there is a possibility that the media group enters between the feed roller 112 and the brake roller 113, resulting in double feeding of the media.

[0101] Also, if the speed of the feed roller 112 at this time is too high, the leading end of the first medium M1 may lift before reaching the nip region between the feed roller 112 and the brake roller 113, and the medium M1 may buckle, resulting in media jamming.

[0102] As shown in steps S103 to S105 of FIG. 8, when feeding the first medium among the media placed on the placement 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 the start of feeding the media by the feed roller 112 until the fifth medium sensor 118 detects the leading end of the media. 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 lower than the first intermediate speed V2a when feeding the second and subsequent media. The control unit 151 can suppress the occurrence of double feeding or jamming of the media by reducing the speed of the feed roller 112 during the separation period of the first medium.

[0103] On the one hand, as shown in Fig. 13(b), when the first medium M1 is fed, the subsequent media M2 are separated by the brake roller 113, and the leading ends of the respective media M2 are in contact with the brake roller 113. Similar to the case where the first medium M1 is fed, if the speed of the feed roller 112 is too high, there is a possibility of media double feed or jam when the subsequent media M2 are fed. However, compared with the case where the first medium M1 is fed, the possibility of media double feed or jam when the subsequent media M2 are fed is low. On the other hand, if the feed speed during the separation period of the subsequent media M2 is too low, a great deal of time is required until the conveyance of all the media is completed. However, when feeding the subsequent media M2, if the speed of the stopped feed roller 112 is suddenly increased, there is a possibility of out-of-tune of the first motor 131.

[0104] As shown in steps S112 to S115 and S118 of Fig. 9, when the conveyance 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 higher than the initial speed V1 when feeding the first medium during the separation period when feeding the subsequent media. The separation period when feeding the subsequent media is the period from time T4 to time T5 in Figs. 10 to 12. In particular, when feeding the subsequent media 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 second intermediate speed V2b after rotating it at the first intermediate speed V2a. In this way, the control unit 151 gradually increases the speed of the feed roller 112 during the separation period of the subsequent media to a speed higher than the speed during the separation period of the first medium while reducing the speed. Thereby, the control unit 151 can reduce the processing time required for the media reading process while suppressing the occurrence of media double feed or jam and out-of-tune of the first motor 131, and can achieve both feeding performance (reduction of abnormal occurrence) and processing performance (reduction of conveyance time).

[0105] FIG. 14 is a schematic diagram for explaining the technical significance of feeding a medium according to the medium reading process shown in FIGS. 8 and 9. FIG. 14 is a schematic diagram of the lower guide 101a of the lower housing 101 as viewed from above.

[0106] FIG. 14 shows a state where the leading end of the tilted medium M3 is in contact with only one of the two transport rollers 119 (the first opposing rollers 120). When the speed of the transport roller 119 is substantially the same as the speed of the feed roller 112, the medium M3 is then transported downstream while maintaining the current tilt. However, when the speed of the transport roller 119 is higher than the speed of the feed roller 112, the medium M3 is then pulled by the transport roller 119 on the contacting side and rotates in the direction of arrow A9. Therefore, the tilt of the medium M3 increases, and the medium M3 may collide with the side wall of the transport path, resulting in a jam of the medium. The greater the difference between the speed of the transport roller 119 and the speed of the feed roller 112, the higher the possibility of a medium jam occurring.

[0107] As described above, when the free capacity of the storage device 140 is insufficient or the distance between the media is short when the leading end of the medium passes the position of the fifth medium sensor 118, the control unit 151 may temporarily stop feeding the medium. However, when the control unit 151 temporarily stops feeding the medium, after restarting the feeding of the medium, a certain acceleration period is required until the speed of the feed roller 112 reaches the set speed. When the leading end of the medium reaches the position of the transport roller 119 and the speed of the feed roller 112 has not increased sufficiently, skew of the medium may occur. Therefore, when the control unit 151 temporarily stops feeding the medium, it is necessary to stop the medium at a position sufficiently upstream of the transport roller 119. However, a certain deceleration period is required until the rotation of the feed roller 112 completely stops after the control unit 151 stops the first motor 131. For example, by making the distance between the feed roller 112 and the transport roller 119 sufficiently large, the above problems can be avoided, but in that case, the size of the entire apparatus increases.

[0108] As shown in steps S106 and S119 of FIGS. 8 and 9, in the high-speed mode, after the fifth medium sensor 118 detects the leading end of the medium, the control unit 151 controls the first motor 131 to rotate the feed roller 112 at a final speed V3a higher than the second intermediate speed V2b. Therefore, when the leading end of the medium passes the position of the fifth medium sensor 118, the speed of the feed roller 112 is set to the second intermediate speed V2b lower than the final speed V3a, and the control unit 151 can completely stop the rotation of the feed roller 112 in a sufficiently short time. In the medium-speed mode and the low-speed mode, when the leading end of the medium passes the position of the fifth medium sensor 118, the speeds of the feed roller 112 are set to the final speed V3b and the final speed V3c. However, since the final speed V3b and the final speed V3c are lower than the 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 the feeding of the medium, it can stop the medium at a position sufficiently upstream of the conveying roller 119. Thereby, when the control unit 151 resumes the feeding of the medium, it can sufficiently increase the speed of the feed roller 112 before the leading end of the medium reaches the position of the conveying roller 119, suppress an increase in the inclination of the medium, and suppress the occurrence of jamming of the medium.

[0110] Also, as shown in steps S114 and S115 of FIG. 9, when the control unit 151 feeds the second and subsequent media, during the separation period, when the second media sensor 114 detects the leading edge of the media, 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 media passes the position of the second media sensor 114, that is, after passing through the nip area between the feed roller 112 and the brake roller 113, the leading edge of the media will not collide with the brake roller 113 and lift up. Therefore, the possibility that the media buckles and a jam of the media occurs is low. When the second media sensor 114 detects the leading edge of the media, the control unit 151 assumes that the leading edge of the media 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. Thereby, the control unit 151 can reduce the feeding time of the media while suppressing the occurrence of a jam of the media.

[0111] In particular, since the period during which the feed roller 112 rotates at the first intermediate speed V2a becomes shorter and the period during which it rotates at the second intermediate speed V2b becomes longer, even if the second intermediate speed V2b is low, the total feeding speed of the media can be made high. That is, the control unit 151 can lower the second intermediate speed V2b, and when temporarily stopping the feeding of the media as described above, it is possible to stop the media at a position sufficiently upstream of the conveying roller 119. In steps S114 and S115 of FIG. 9, the control unit 151 may change the speed of the feed roller 112 not when the leading edge of the media passes the position of the second media sensor 114, but when a fourth predetermined time has elapsed since the start of the feeding of the media. The fourth predetermined time is set, through prior experiments, to the time required for the leading edge of the media to pass through the nip area between the feed roller 112 and the brake roller 113 since the start of the feeding of the media. In that case, the second media sensor 114 may be omitted. Also, when the second media sensor 114 is omitted, the fifth media sensor 118 may be arranged at the position of the second media sensor 114.

[0112] Further, during the ramp-up period of the first motor 131 and / or the second motor 132, the control unit 151 may increase the amount of current supplied to the first motor 131 and / or the second motor 132. Thereby, even if the speed of each motor is increased in a short period, the possibility of out-of-step of each motor is reduced, and the distance required for ramp-up can be reduced. Also, by limiting the period during which the current amount is increased to the ramp-up period, the medium conveyance device 100 can suppress an increase in the overall power consumption.

[0113] Also, as shown in FIG. 13(b), the medium that has entered the nip region between the feed roller 112 and the brake roller 113 is pushed back by the brake roller 113 that rotates in the direction opposite to the medium feed direction. The larger the ratio of the speed of the brake roller 113 to the speed of the feed roller 112, the better the medium is pushed back. In particular, as shown in FIG. 13(a), when starting to feed the first medium M1, the leading ends of the respective media arranged above the first medium M1 have not reached the nip region between the feed roller 112 and the brake roller 113. Therefore, when starting to feed the first medium M1, the respective media vigorously enter the nip region between the feed roller 112 and the brake roller 113. Thus, 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 well returned to the upstream side.

[0114] On the other hand, as shown in FIG. 13(b), when feeding the second and subsequent media M2, the leading ends of the respective media M2 are already in contact with the brake roller 113. Therefore, when feeding the second and subsequent media 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, the media other than the fed media are well pushed back.

[0115] Also, as described above, the brake roller 113 is driven by the same second motor 132 as the conveying roller 119 and the discharging roller 123. Thereby, the medium conveying device 100 can reduce the number of motors and reduce the device cost and the device size. However, when the speed of the brake roller 113 is reduced, the speeds of the conveying roller 119 and the discharging roller 123 are also reduced, and the processing performance of the medium is reduced.

[0116] Also, the higher the speed of the brake roller 113, the greater the vibration of the brake roller 113, and a large-volume vibration sound (so-called rattling sound) is generated. When starting the feeding of the second and subsequent media, the medium is in contact with the brake roller 113, and the vibration is suppressed. However, when starting the feeding of the first medium M1, the medium is not in contact with the brake roller 113, and the vibration is not suppressed. Therefore, it is particularly desirable to reduce the speed of the brake roller 113 when starting the feeding of 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 and subsequent media. Thereby, the control unit 151 can suppress the vibration of the brake roller 113 when feeding the first medium and suppress the generation of vibration sound. During the separation period when feeding the first medium, the conveying roller 119 has not yet conveyed the medium, and even if the rotational speed of the brake roller 113 is reduced, the conveying time of the medium does not increase. On the other hand, the control unit 151 can maintain the rotational speed of the conveying roller 119 at a high level by increasing the rotational speed of the brake roller 113 during the separation period when feeding the second and subsequent media. Therefore, the medium conveying device 100 can improve the processing performance (reduction of conveying time) while suppressing an increase in device cost and device size.

[0118] Also, as shown in step S103 of FIG. 8, at the start of media feeding, the control unit 151 sets the speed of the feeding 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 of the initial speed V1 of the feeding 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 media among the media placed on the mounting table 103 is higher than half of the speed of the feeding roller 112 during the separation period when feeding the first media. Thereby, the brake roller 113 can satisfactorily push back the media that has entered the nip area between the feeding roller 112 and the brake roller 113 during media feeding.

[0119] As described in detail above, during the period from the start of media feeding until the leading end of the media passes through the feeding roller 112, the media conveyance device 100 gradually increases the rotational speed of the feeding roller 112. Thereby, the media conveyance device 100 can appropriately control the stop and restart of media feeding when the free capacity of the storage device 140 is insufficient, or when the distance between continuously fed media is short, while reducing the media feeding time. Therefore, the media conveyance device 100 can control media feeding better.

[0120] In particular, the media conveyance device 100 can control media feeding better without using a motor with a special configuration or a media sensor by devising a motor control method. Therefore, the media conveyance device 100 controls media feeding better while suppressing an increase in device cost and device size.

[0121] Also, the media conveyance device 100 rotates the feeding roller 112 at a low speed during media separation and rotates the feeding roller 112 at a high speed when the media is not being separated, thereby enabling the media to be separated well and conveyed in a short time.

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

[0123] As shown in FIG. 15, the media transport device according to this embodiment has a transport roller 219, a first opposing roller 220, a discharge roller 223, and a second opposing roller 224 instead of the transport roller 119, the first opposing roller 120, the discharge roller 123, and the second opposing roller 124. Further, the media transport device has a second motor 232 instead of the second motor 132.

[0124] The transport roller 219 is provided on the lower housing 101, and the first opposing roller 220 is provided on the upper housing 102 above the transport roller 219. The discharge roller 223 is provided on the lower housing 101, and the second opposing roller 224 is provided on 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 roller 219, the discharge roller 223, and the brake roller 113 via the second transmission mechanism 232a to drive the conveying roller 219, the discharge roller 223, and the brake roller 113. The second motor 232 generates a driving force for driving the conveying roller 219, the discharge roller 223, and the brake roller 113 according to a control signal 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 for making the rotation directions and rotation speeds of the respective rollers different are provided between the shaft 219a of the conveying roller 219 and / or the shaft 223a of the discharge roller 223 and the shaft 113a of the brake roller 113. These gears are arranged outside the media conveyance path in the width direction A8 so as to transmit the driving force across the media conveyance path. The second transmission mechanism 232a transmits the driving force generated by the second motor 232 to the conveying roller 219, the discharge roller 223, and the brake roller 113. Thereby, the second motor 232 rotates the conveying roller 219, the discharge roller 223, and the brake roller 113 to feed, convey, and discharge the media to and from the conveying roller 219, the discharge roller 223, and the brake roller 113. The second motor 232 is an example of a driving 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. Note that the first opposing roller 220 and / or the second opposing roller 224 may be provided to be driven by the driving force from the second motor 232. In that 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 in detail above, when the medium conveyance device is provided with the conveyance roller 219 in the lower housing 101 and the conveyance roller 219 and the brake roller 113 are driven by the same second motor 232, it becomes possible to control the feeding of the medium better.

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

[0129] The flowchart shown in FIG. 16 is executed instead of the flowchart shown in FIG. 9. Since the processes of steps S211 to S213, S216 to S223 in FIG. 16 are the same as the processes of steps S111 to S113, S116 to S123 in FIG. 9, the description thereof is omitted, and hereinafter, only steps S214 to S215 will be described.

[0130] After the control unit 151 drives the feed roller 112 in step S213, the determination unit 152 determines whether skew of the conveyed 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 end 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 the absence of the medium to a value indicating the presence of the medium. Further, the determination unit 152 determines that the leading end 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 the absence of the medium to a value indicating the presence of the medium.

[0131] If the leading end of the medium does not pass the other position within the fifth predetermined time after passing one of the positions of the third medium sensor 116 and the fourth medium sensor 117, the determination unit 152 determines that skew of the medium has occurred. The fifth predetermined time is set to a value between the difference in passing times of the positions of the respective sensors when no jam of the medium occurs and the difference in passing times of the positions of the respective sensors when a jam of the medium occurs, based on prior experiments. On the other hand, if the leading end of the medium passes the other position within the fifth predetermined time after passing one of the positions of the third medium sensor 116 and the fourth medium sensor 117, the determination unit 152 determines that no skew of the medium has occurred.

[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 conveyance 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 conveyance 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 conveyance 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 FIG. 17, the graph G41 shows the speed change of the feed roller 112. The horizontal axis of the graph G41 indicates time, and the vertical axis indicates speed. Note that the speeds of the brake roller 113 and the conveyance roller 119 change in the same manner as the graphs G12 and G13 shown in FIG. 10. The graphs G14 and G15 show the changes in the signal values of the fifth medium sensor 118 and the sixth medium sensor 121, and change in the same manner as the graphs G14 and G15 shown in FIG. 10. Also, the times T1 to T6 indicate the same times as the times T1 to T6 shown in FIG. 10.

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

[0136] As described above, when the free capacity of the storage device 140 is insufficient or the distance between the media is short, the control unit 151 may temporarily stop feeding the media. However, when the media is tilted and the speed of the conveyance roller 119 is higher than the speed of the feed roller 112, the tilt of the media may increase, and the media may collide with the side wall of the conveyance path, resulting in media jamming. When the skew of the media occurs, the control unit 151 sets the speed of the feed roller 112 to the second intermediate speed V2b, so that when the feeding of the media is temporarily stopped, the media can be stopped at a position sufficiently upstream of the conveyance roller 119. As a result, when the control unit 151 resumes feeding the media, it is possible to sufficiently increase the speed of the feed roller 112 before the leading end of the media reaches the position of the conveyance roller 119, suppressing an increase in the tilt of the media and suppressing the occurrence of media jamming.

[0137] On the other hand, when the media is not tilted, even if the speed of the conveyance roller 119 is higher than the speed of the feed roller 112, the likelihood of an increase in the tilt of the media and media jamming is low. When no skew of the media occurs, the control unit 151 can reduce the media feeding time by setting the speed of the feed roller 112 to the final speed V3a. Therefore, the control unit 151 can reduce the media conveyance time while suppressing the occurrence of media jamming.

[0138] As described in detail above, even when the media conveyance device changes the speed of the feed roller 112 depending on whether skew of the media has occurred, it is possible to better control the feeding of the media.

[0139] FIG. 18 is a flowchart showing an example of a part of the operation of the media reading process of a media conveyance device according to still another embodiment.

[0140] The flowchart shown in FIG. 18 is executed instead of the flowchart shown in FIG. 8. Since the processes of steps S301 to S306 and S308 to S311 in FIG. 18 are the same as the processes of steps S101 to S106 and S107 to S110 in FIG. 8, the description thereof will be omitted, and hereinafter, only steps S307 and S312 will be described.

[0141] After waiting until the leading end of the medium passes the position of the fifth medium sensor 118 in step S305 or S118, that is, after the leading end of the medium has passed the position of the ultrasonic sensor 115, the control unit 151 detects the thickness of the conveyed medium (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 wave transmitted by the ultrasonic transmitter 115a and passing through the medium is attenuated by the medium, and the greater the thickness of the medium, the greater the attenuation amount of the ultrasonic wave. The medium conveying device 100 stores in advance in the storage device 140 a table defining the relationship between the magnitude of the ultrasonic wave received by the ultrasonic receiver 115b, that is, the signal value of the ultrasonic signal, and the thickness of the medium. The control unit 151 refers to the table stored in the storage device 140 and specifies the thickness of the medium corresponding to the signal value of the received ultrasonic signal.

[0142] Note that the control unit 151 may further determine whether or not double feeding of the medium has occurred based on the ultrasonic signal received from the ultrasonic sensor 115. When a plurality of media are conveyed overlapping each other, the ultrasonic wave that penetrates the media is attenuated in the air layer between the overlapping media. Therefore, the control unit 151 can determine whether or not double feeding of the medium has occurred based on whether or not the signal value of the ultrasonic signal is equal to or less than the double feed threshold value. The double feed threshold value is set to a value between the signal value of the ultrasonic signal when a single sheet of paper is conveyed and the signal value of the ultrasonic signal when two sheets of paper are conveyed. When it is determined that double feeding of the medium has occurred, the control unit 151 stops the first motor 131 and the second motor 132 to stop the conveyance and discharge of the medium. Note that the control unit 151 may stop the medium reading process after discharging the medium currently being conveyed. Further, the control unit 151 may control each roller so as to drive each motor, reverse-feed the medium remaining in the conveyance path, temporarily return it to the mounting table 103, and then re-feed (separate) it. Thereby, the user does not need to re-mount and re-feed the medium on the mounting table 103, and the control unit 151 can improve the convenience for the user. Further, the control unit 151 may notify the user by displaying information indicating that double feeding of the medium has occurred on the display device 106 or transmitting it to the information processing device via the interface device 135.

[0143] Further, the control unit 151 may detect the thickness of the medium using a thickness sensor other than the ultrasonic sensor 115. The thickness sensor is disposed at the position where the ultrasonic sensor 115 is disposed. Note that the thickness sensor may be disposed at any position on the medium conveyance path. The thickness sensor is, for example, a reflection light sensor including a pair of a light emitter and a light receiver provided on one side with respect to the medium conveyance path and a pair of a light emitter and a light receiver provided on the other side. The reflection light sensor detects the distance from each pair to each surface of the medium from the time from when one pair irradiates light on one surface of the medium until the reflected light is received and the time from when the other pair irradiates light on the other surface of the medium until the reflected light is received. The reflection light sensor generates a thickness signal indicating the subtraction value obtained by subtracting the detected distances from the distance between the two pairs as the thickness. The medium conveyance device 100 stores in advance in the storage device 140 a table defining 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 specifies 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 using light, and as the thickness sensor, any other sensor capable of detecting the thickness of the medium, such as a pressure sensor or a thickness sensor using a contact piece, may be used.

[0144] On the other hand, in step S311, after waiting until the rear end of the medium passes the position of the fifth medium sensor 118, the control unit 151 detects the size of the conveyed medium (step S312). The control unit 151 detects, for example, the length of the medium in the medium conveyance direction A1 as the size of the medium. The control unit 151 detects the length of the medium in the medium conveyance direction A1 based on the fifth medium signal received from the fifth medium sensor 118. The control unit 151 calculates, as the length of the medium in the medium conveyance direction A1, the distance by which the first motor 131 is driven to move the medium by the feed roller 112 during the period from when the fifth medium sensor 118 detects the front end of the medium until it detects the rear end of the medium. That is, the control unit 151 calculates, as the length of the medium in the medium conveyance direction A1, the value obtained by multiplying the conveyance speed of the medium by the time from when the fifth medium sensor 118 detects the front end of the medium until it detects the rear end of the medium.

[0145] Note that 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 conveyance device 100 arranges a number of fifth medium sensors 118 at intervals in the width direction A8, and stores in advance the arrangement intervals of the respective 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 have detected the conveyed medium.

[0146] Further, when the imaging of the medium is completed, the control unit 151 may detect the length of the medium in the medium conveyance 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 known image processing techniques to detect the edge of the medium from the input image, and based on the distance between the upper and lower ends or the left and right ends of the medium, detects the length of the medium in the medium conveyance direction A1 or the width direction A8.

[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 speed change of the feed roller 112 in the high-speed mode.

[0149] In FIG. 19, graphs G51 and G52 show an example of the speed change of the feed roller 112. The horizontal axis of graphs G51 and G52 indicates time, and the vertical axis indicates speed. Note that the speeds of the brake roller 113 and the conveyance roller 119 change in the same manner as graphs G12 and G13 shown in FIG. 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 manner as graphs G14 and G15 shown in FIG. 10. Also, times T1 to T6 indicate the same times as times T1 to T6 shown in FIG. 10.

[0150] In step S115, when the size of the medium is equal to or less 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 the second intermediate speed V2b as shown in the graph G11 of FIG. 10. For example, when the first size threshold is the length of the medium in the medium conveyance direction A1, it is set to a value between the A4 vertical size and the A3 vertical size, and when the size of the medium is the length of the medium in the width direction A8, it is set to a value between the A4 horizontal size and the A3 horizontal size. The second size threshold is set to a value smaller than the first size threshold. For example, when the second size threshold is the length of the medium in the medium conveyance direction A1, it is set to a value between the A5 vertical size and the A4 vertical size, and when the size of the medium is the length of the medium in the width direction A8, it is set to a value between the A5 horizontal size and the A4 horizontal size. The first size threshold and the second size threshold are examples of size thresholds.

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

[0152] Also, in step S119, when the size of the medium is equal to or less 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 the final speed V3a as shown in the graph G11 in FIG. 10. On the other hand, when the size of the medium is greater than the first size threshold, the control unit 151 changes the speed of the feed roller 112 to the final speed V3d as shown in the graph G51. The final speed V3d is set to a speed higher than the final speed V3a when the size of the medium is equal to or less 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 the final speed V3d, as shown by the dotted line D1 in the graph G51, the control unit 151 may change the speed of the feed roller 112 to the final speed V3a before the leading edge of the subsequent medium passes through the position of the fifth medium sensor 118. 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 subsequent medium passes through the position of the transport roller 119. Thereby, the control unit 151 can suppress the medium from being pushed by the feed roller 112 and being bent between the feed roller 112 and the transport roller 119, and prevent the occurrence of a jam of the medium. Further, when the size of the medium is equal to or less 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 the graph G52.

[0153] Note that when the size of the medium is greater 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 less than the first size threshold and greater than the second size threshold. Alternatively, when the size of the medium is equal to or less 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 less than the first size threshold and greater than the second size threshold.

[0154] In this way, when the size of the preceding medium is small, the control unit 151 reduces the speed of the feed roller 112 after the leading end of the subsequent medium has passed through the nip area between the feed roller 112 and the brake roller 113 to a speed lower than that 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 less than the size threshold to a speed lower than the second speed when the size of the preceding medium is greater than the size threshold.

[0155] Generally, the shorter the length of the medium, the shorter the distance between the continuously conveyed media tends to be. By reducing the speed of the feed roller 112 when the size of the preceding medium is small to a speed lower than that when the size of the preceding medium is large, the control unit 151 can prevent the continuously conveyed media from colliding with each other.

[0156] When the flowchart shown in FIG. 18 is executed, in step 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, when 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 the second intermediate speed V2b as shown in the 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 general 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 general 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 the second intermediate speed V2c as shown in the graph G51. Also, 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 the second intermediate speed V2d as shown in the graph G52.

[0159] Also, in step S119, when 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 the final speed V3a as shown in the graph G11 in FIG. 10. 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 the final speed V3d as shown in the graph G51. Further, when 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 the second intermediate speed V2b as shown in the graph G52.

[0160] Note that 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 makes the speed of the feed roller 112 after the leading end of the subsequent medium has passed through the nip region between the feed roller 112 and the brake roller 113 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 be 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 a jam of the medium will occur. By making the speed of the feed roller 112 when the preceding medium is thin lower than the speed of the feed roller 112 when the preceding medium is thick, the control unit 151 can suppress the occurrence of a jam of the medium.

[0163] Note that either one of the processes in steps S307 and S311 may be omitted. Further, the control unit 151 may change the speed of the feed roller 112 based on both the size and thickness of the medium. In that case, the control unit 151 decreases the speed of the feed roller 112 as the preceding medium is shorter, and decreases the speed of the feed roller 112 as the preceding medium is thinner.

[0164] As described in detail above, even when the medium conveyance device changes the speed of the feed roller 112 based on the size or thickness of the medium, it has become possible to better control the feeding of the medium.

[0165] FIGS. 20 and 21 are flowcharts showing examples of operations of the medium reading process of the medium conveyance device according to still other embodiments.

[0166] The flowcharts shown in FIGS. 20 and 21 are executed instead of the flowcharts shown in FIGS. 8 and 9. Since the processes in steps S401 to S407, S409 to S411, S413 to S417, and S422 to S426 in FIGS. 20 and 21 are the same as the processes in steps S101 to S107, S109 to S111, S114 to S118, and S119 to S123 in FIGS. 8 and 9, the description thereof is omitted. Hereinafter, only steps S408, S412, and S418 to S421 will be described.

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

[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 speed change of the feed roller 112. The horizontal axis of graph G61 indicates time, and the vertical axis indicates speed. Note that the speeds of the brake roller 113 and the conveying roller 119 change in the same manner as graphs G12 and G13 shown in FIG. 10. Graphs G64 and G65 show the changes in the signal values of the fifth medium sensor 118 and the sixth medium sensor 121. The horizontal axis of each of graphs G64 and G65 indicates time, and the vertical axis indicates the signal value. Also, times T1 to T6 indicate the same times as times T1 to T6 shown in FIG. 10. However, in the examples shown in graphs G61, G64, and G65, compared with the examples shown in each graph of FIG. 10, the distance between the rear end of the preceding medium and the front end of the subsequent medium is short, and the time between time T4 and time T5 is short.

[0170] As shown in graph G61, between time T3 and time T4, when the front end of the medium passes through the conveying roller 119, the speed of the feed roller 112 is reduced but not zero. Thereby, the control unit 151 can suppress the occurrence of jamming of the medium between the feed roller 112 and the conveying roller 119, shorten the distance between the continuously fed media, and reduce the conveyance time of the medium.

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

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

[0173] Next, the control unit 151 determines whether or not 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 proceeds to step S422.

[0174] On the other hand, if the medium interval is equal to or less than the predetermined time, the control unit 151 determines a 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 temporarily stopped until the rotation of the feed roller 112 is restarted, 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 such that the shorter the medium interval, the longer the deceleration time, and the longer the medium interval, the shorter the deceleration time. The medium conveyance device 100 stores in advance in the storage device 140 a table defining 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 and specifies the deceleration time corresponding to the medium interval.

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

[0177] As shown in the graph G61 of FIG. 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 feeding roller 112 to a predetermined speed. For example, as shown by the solid line L2 in the graph G61, the control unit 151 changes the speed of the feeding roller 112 to a speed lower than at least the second intermediate speed V2b and decelerates the feeding roller 112. Note that the control unit 151 may change the speed of the feeding roller 112 to 0 and stop the feeding roller 112 as shown by the dotted line D2 in the 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, when the transport mode is set to the high-speed mode, the control unit 151 changes the speed of the feeding roller 112 to the final speed V3a in the same manner as the process of step S119 in FIG. 9.

[0181] In this way, when the medium interval is equal to or less than a predetermined time, the control unit 151 temporarily stops or decelerates the feeding roller 112. Thereby, the control unit 151 can suppress the occurrence of collisions between continuously fed media.

[0182] Further, when the tip of the subsequent medium passes through the fifth medium sensor 118 in the preceding medium, 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 resume the rotation of the feed roller 112 after temporarily stopping the feed roller 112, or the timing to accelerate the feed roller 112 after decelerating the feed roller 112. Thereby, the control unit 151 appropriately sets the time for decelerating the feed roller 112, and can suppress the occurrence of collisions of the continuously fed media while suppressing an excessive increase in the conveyance time of the media.

[0183] In step S408, the control unit 151 may control the first motor 131 to stop the feed roller 112 in the same manner as in step S108 of FIG. 8. In that case, in step S412, the control unit 151 sets the speed of the feed roller 112 and redrives the first motor 131 in the same manner as in steps S112 and S113 of FIG. 9 to resume the rotation of the feed roller 112.

[0184] As described in detail above, even when the medium conveyance device changes the speed of the feed roller 112 based on the interval between the continuously fed media, it has become possible to better control the feeding of the media.

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

[0186] As shown in FIG. 23, the medium conveyance device according to the present embodiment has a first motor 231 instead of the first motor 131. Further, the medium conveyance 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 on 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 brake roller 113 together with the feed roller 112. The first motor 231 generates a driving force for driving the feed roller 112 and the brake roller 113 according 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, between the shaft 113a of the brake roller 113 and the shaft 112a of the feed roller 112, one or more gears are provided for making the rotation directions and rotation speeds of the respective rollers different. These gears are arranged outside the media conveyance path in the width direction A8 so as to transmit the driving force across the media conveyance path. Thereby, the first motor 231 rotates the feed roller 112 and the brake roller 113 to feed the media. The first motor 231 is an example of a driving source for the brake roller 113.

[0188] Further, since the first motor 231 is provided on the housing on the brake roller 113 side (upper housing 102), the driving force can be surely transmitted to the brake roller 113 before the feed roller 112. Thereby, the first motor 231 can start the rotation of the brake roller 113 before starting the rotation of the feed roller 112, and the media can be stably separated. Also, the first motor 231 and the shaft 113a of the brake roller 113 are preferably directly connected by a belt. Thereby, the first motor 231 can more surely start the rotation of the brake roller 113 before starting the 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 conveyance roller 119 and the discharge roller 123 via a second transmission mechanism 132b, and drives the conveyance roller 119 and the discharge roller 123. The second motor 132 generates a driving force for driving the conveyance roller 119 and the discharge roller 123 according 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 conveyance 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 conveyance roller 119 and the discharge roller 123. Thereby, the second motor 132 rotates the conveyance roller 119 and the discharge roller 123 to convey and discharge the medium to the conveyance roller 119 and the discharge roller 123.

[0190] FIG. 24 and FIG. 25 are flowcharts showing examples of operations of the medium reading process of the medium conveyance device according to still other embodiments.

[0191] The flowcharts shown in FIGS. 24 and 25 are executed instead of the flowcharts shown in FIGS. 8 and 9. Since the processes of steps S501 to S507, S509 to S511, S514, S516 to S518, and S520 to S523 in FIGS. 24 and 25 are the same as the processes of steps S101 to S107, S109 to S111, S114, S116 to S118, and S120 to S123 in FIGS. 8 and 9, the description thereof will be omitted. Hereinafter, only steps S508, S512 to S513, S515, and S519 will be described.

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

[0194] In FIG. 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 conveyance roller 119. The horizontal axis of each of the graphs G71 to G73 indicates time, and the vertical axis indicates speed. Graphs G14 and G15 show the changes in the signal values of the fifth medium sensor 118 and the sixth medium sensor 121, and change in the same manner as the graphs G14 and G15 shown in FIG. 10. Also, times T1 to T6 indicate the same times as the times T1 to T6 shown in FIG. 10.

[0195] When set to the first mode, the control unit 151 controls the first motor 231 so as to stop the feed roller 112 and the brake roller 113. In this case, as shown by the solid line L3 in graph G71 and the solid line L4 in graph G72, between time T3 and time T4, the speeds of the feed roller 112 and the brake roller 113 become 0. Thereby, the control unit 151 can surely suppress the occurrence of a jam of the medium between the feed roller 112 and the conveyance roller 119.

[0196] On the other hand, when set to the second mode, the control unit 151 controls the first motor 231 so as to continue rotating the feed roller 112 and the brake roller 113 while reducing (without stopping) the rotational speeds of the feed roller 112 and the brake roller 113. In this case, as shown by the dotted line D3 in graph G71 and the dotted line D4 in graph G72, between time T3 and time T4, the speeds of the feed roller 112 and the brake roller 113 do not become 0 but are reduced. Thereby, the control unit 151 can suppress the reduction in the separation performance due to stopping the brake roller 113 and can suppress the occurrence of double feeding of the medium.

[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 there is still medium remaining on the placement table 103, the control unit 151 sets the speed of the feed roller 112 for feeding the subsequent medium (step S512).

[0198] When set to the first mode, as shown in graph G71 of FIG. 26, at time T4, the control unit 151 sets the speed of the feed roller 112 to the first intermediate speed V2a. Also, as shown in graph G72, at time T4, the control unit 151 sets the speed of the brake roller 113 to the first intermediate speed U2a. The first intermediate speed U2a is set to a speed 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 speeds (step S513). When set to the first mode and the feed roller 112 and the brake roller 113 are stopped, the control unit 151 resumes the rotation of the feed roller 112 and the brake roller 113 to feed and convey the subsequent medium.

[0200] On the other hand, when set to the second mode 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 the first intermediate speed V2a and increases the speed of the brake roller 113 to the first intermediate speed U2a.

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

[0202] As shown in graph G71 of FIG. 26, the control unit 151 changes the speed of the feed roller 112 to the second intermediate speed V2b. Also, as shown in graph G72, the control unit 151 changes the speed of the brake roller 113 to the 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 subsequent medium passes the position of the fifth medium sensor 118 in step S518, the control unit 151 changes the speeds of the feed roller 112 and the brake roller 113 (step S519).

[0204] As shown in graph G71 of FIG. 26, at time T5, the control unit 151 changes the speed of the feed roller 112 to the final speed V3a. Also, as shown in graph G72, the control unit 151 changes the speed of the brake roller 113 to the 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 conveying 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 continuously transmitting the driving force from the first motor 231 to the brake roller 113. In that 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. Thereby, the control unit 151 can suppress the reduction of the separation performance due to stopping the brake roller 113 and suppress the narrowing of the distance between the continuously fed media.

[0206] In this embodiment, since the feeding roller 112 and the brake roller 113 are driven by the same first motor 231, the speed of the feeding roller 112 and the speed of the brake roller 113 have a proportional relationship. Note that the speed of the brake roller 113 is set to be lower than the speed of the feeding roller 112 and higher than 1 / 2 of the speed of the feeding roller 112.

[0207] Also, the medium conveyance device may operate fixedly in either one of the first mode and the second mode.

[0208] As described in detail above, even when the medium conveyance device drives the feeding roller 112 and the brake roller 113 with the same first motor 231, it is possible to better control the feeding of the medium.

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

[0210] As shown in FIG. 27, the medium conveyance device according to this embodiment has a conveyance roller 219, a first opposing roller 220, a discharge roller 223, and a second opposing roller 224 instead of the conveyance roller 119, the first opposing roller 120, the discharge roller 123, and the second opposing roller 124. The configurations of the conveyance 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 conveyance roller 219, the first opposing roller 220, the discharge roller 223, and the second opposing roller 224 in the medium conveyance device shown in FIG. 15. Also, the medium conveyance device 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 conveyance device shown in FIG. 15. Also, the medium conveyance device 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 conveyance device shown in FIG. 23.

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

[0212] As described in detail above, even when the medium conveyance device drives the feed roller 112 and the brake roller 113 with the same first motor 231 while providing the conveyance roller 219 in the lower housing 101, it is possible to better control the feeding of the medium.

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

[0214] As shown in FIG. 28, the medium conveyance device according to the present embodiment has a third motor 336 in addition to the first motor 131. Further, the medium conveyance device has a first transmission mechanism 131b instead of the first transmission mechanism 131a of the first motor 131, and 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 the same as the configuration of the second motor 132 shown in FIG. 23.

[0215] The first motor 131 is connected to the feed roller 112 via the first transmission mechanism 131b and drives the feed roller 112. The first motor 131 generates a driving force for driving the feed roller 112 according 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. Thereby, the first motor 131 rotates the feed roller 112 to feed the medium.

[0216] The third motor 336 is provided on 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 according to a control signal from the processing circuit 150. The third transmission mechanism 336a includes one or a plurality of 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. Thereby, the third motor 336 rotates the brake roller 113 to feed the medium. The third motor 336 is an example of a driving source of the brake roller 113.

[0217] FIG. 29 is a flowchart showing an example of a part of the operation of the medium reading process of the medium conveyance device according to still another embodiment.

[0218] The flowchart shown in FIG. 29 is executed instead of the flowchart shown in FIG. 9. Since the processes of steps S611, S614 to S615, S616, S618, S620, S622 to S625 in FIG. 29 are the same as the processes of steps S111, S112 to S113, S116, S117, S118, S120 to S123 in FIG. 9, the description thereof will be omitted. Hereinafter, only steps S612 to S613, S617, S619, and S621 will be described.

[0219] After waiting until the rear end of the medium passes the position of the fifth medium sensor 118 in step S110, when it is determined in step S611 that there is still a medium on the mounting table 103, the control unit 151 controls the second motor 132 to reduce the speed of the conveying roller 119 (step S612). That is, when the rear end of the medium passes the fifth medium sensor 118, the control unit 151 reduces the rotational speed of the conveying roller 119.

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

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

[0222] As shown in graph G83, the control unit 151 reduces the speed of the conveyance roller 119 at time T4 when the rear end of the medium passes through the fifth medium sensor 118. A force that tries to hold the medium upstream acts on the medium being separated by the feed roller 112 and the brake roller 113. When the rear end of the medium separates from the feed roller 112 and the brake roller 113, this force disappears, so the conveyance speed of the medium tends to increase. The control unit 151 can convey the medium at a stable speed by reducing the speed of the conveyance roller 119 when the rear end of the medium passes through the feed roller 112 and the brake roller 113.

[0223] Next, the control unit 151 waits until the sixth predetermined time elapses (step S613). The sixth predetermined time is set to a time that can delay the feeding of the medium by the feed roller 112 by the amount by which the conveyance of the medium by the conveyance roller 119 is delayed by decelerating the conveyance roller 119. Thereby, the control unit 151 can delay the feeding of the medium by the feed roller 112 by the amount by which the conveyance of the medium by the conveyance roller 119 is delayed, and can convey the medium at a stable speed. Note that the process 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 conveyance 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 conveyance roller 119.

[0225] As shown in graph G83 of FIG. 30, between time T4 and time T5, when the rear end of the medium passes the imaging position, the control unit 151 increases the speed of the conveyance roller 119. By changing the speed of the conveyance roller 119 after the rear end of the medium has passed the imaging position, the control unit 151 can suppress the occurrence of stretching or shrinking of the medium included in the input image. Further, when the rear end of the medium passes through the conveyance roller 119 and the first opposing roller 120, the conveyance force applied to the medium decreases, and the conveyance speed of the medium tends to decrease. After the rear end of the medium has passed through the conveyance roller 119 and the first opposing roller 120, the control unit 151 can convey the medium at a stable speed by increasing the speed of the discharge roller 123.

[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 through the conveyance roller 119, the control unit 151 increases the rotational speed of the feed roller 112.

[0227] As shown by the solid line L5 in graph G81 of FIG. 30, after the rear end of the medium has passed the position of the conveyance roller 119 (after the signal value of graph G15 has changed from H to L), the control unit 151 increases the speed of the feed roller 112 to the second intermediate speed V2b. In particular, after increasing the speed of the conveyance roller 119, the control unit 151 increases the speed of the feed roller 112. Thereby, the control unit 151 can suppress the medium from being pushed by the feed roller 112 and bending between the feed roller 112 and the conveyance roller 119, and prevent paper jams of the medium.

[0228] Note that, as shown by the dotted line D5 in the graph G81, after the rear end of the medium has passed the position of the conveyance roller 119, the control unit 151 may increase the speed of the feed roller 112 to the final speed V3a that is higher than the second intermediate speed V2b. Thereby, the control unit 151 can recover the delay in the conveyance of the medium by the conveyance roller 119 and the feed roller 112.

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

[0230] As shown by the solid line L6 in the graph G81 of FIG. 30, the control unit 151 increases the speed of the feed roller 112 to the final speed V3a at time T5. Note that, as shown by the dotted line D6 in the graph G81, the control unit 151 may increase the speed of the feed roller 112 to the final speed V3d that is higher than the final speed V3a at time T5. Thereby, the control unit 151 can recover the delay in the conveyance of the medium by the conveyance roller 119 and the feed roller 112. Note that when the control unit 151 changes the speed of the feed roller 112 to the final speed V3d, as shown by the dotted line D7 in the graph G81, before the leading end of the subsequent medium passes the position of the fifth medium sensor 118, the control unit 151 may change the speed of the feed roller 112 to the final speed V3a. Thereby, the control unit 151 can suppress the medium from being pushed by the feed roller 112 and being bent between the feed roller 112 and the conveyance roller 119, and prevent the occurrence of a jam of the medium.

[0231] In the present embodiment, since the drive source of the feed roller 112, the drive source of the brake roller 113, and the drive sources of the conveyance roller 119 and the discharge roller 123 are provided separately, the speeds of the respective rollers can be changed at independent timings. Therefore, the control unit 151 can flexibly control the feeding and conveyance of the medium.

[0232] Note that, as shown by the dotted line D8 in graph G82, the control unit 151 may temporarily stop the brake roller 113 while the rear end of the medium is passing through the nip area between the feed roller 112 and the brake roller 113, and resume the rotation of the brake roller 113 after the medium has passed through the nip area. Alternatively, as shown by the dotted line D9 in graph G82, the control unit 151 may reduce the speed of the brake roller 113 while the rear end of the medium is passing through the nip area, and increase the speed of the brake roller 113 after the medium has passed through the nip area to return to the final speed U3a. When the rear end of the preceding medium passes through the nip area between the feed roller 112 and the brake roller 113, the load in the medium feed direction applied to the brake roller 113 by the medium is reduced, and the brake roller 113 may rotate vigorously in the direction opposite to the medium feed direction. Also, at that time, the elastically deformed portions of the feed roller 112 and the brake roller 113 return to their original shapes, and there is a possibility that the subsequent medium is pushed back upstream. In that case, the leading end of the subsequent medium may be pushed up (rolled up) by the brake roller 113, and a jam of the medium may occur. The control unit 151 can suppress the leading end of the subsequent medium from being rolled up and the occurrence of a jam of the medium by reducing the speed of the brake roller 113 when the rear end of the medium passes through the nip area.

[0233] Also, the control unit 151 may start the rotation of the brake roller 113 earlier than the rotation of the feed roller 112. Thereby, the control unit 151 can suppress a plurality of media placed on the mounting table 103 from avalanching between the feed roller 112 and the brake roller 113, and can suppress the occurrence of double feeding of the media.

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

[0235] Note that even when changing the speed of the media conveyance device's conveyance roller 119, the brake roller 113 may be driven by either the first motor or the second motor. In that case, the control unit 151 matches the timing of changing the speed of the brake roller 113 to the timing of changing the speed of the feed roller 112 or the conveyance roller 119. Further, the control unit 151 may 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. Also, the media conveyance device has a driving force interruption mechanism such as an electromagnetic clutch between the conveyance roller 119 and the second motor, and the control unit 151 may change the speed of the conveyance 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 conveyance roller 219, the first opposing roller 220, the discharge roller 223, and / or the second opposing roller 224 in a media conveyance device according to still another embodiment.

[0237] As shown in FIG. 31, the media conveyance device according to the present embodiment has a conveyance roller 219, a first opposing roller 220, a discharge roller 223, and a second opposing roller 224 instead of the conveyance roller 119, the first opposing roller 120, the discharge roller 123, and the second opposing roller 124. The configurations of the conveyance 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 conveyance roller 219, the first opposing roller 220, the discharge roller 223, and the second opposing roller 224 in the media conveyance device shown in FIG. 15. Also, the media conveyance device 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 media conveyance device shown in FIG. 15. Further, the media conveyance device 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 media conveyance device shown in FIG. 28.

[0238] That is, in the medium conveyance device according to the present embodiment, similarly to the medium conveyance device shown in FIG. 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 conveyance roller 219 and the discharge roller 223.

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

[0240] FIG. 32 is a flowchart showing an example of a part of the operation of the medium reading process of the medium conveyance device according to still another embodiment. The medium conveyance device according to the present 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 instead of the flowchart shown in FIG. 9. Since the processes in steps S711, S714 to S716, S719 to S721, S724, and S727 to S731 in FIG. 32 are the same as the processes in steps S111, S112 to S114, S115 to S117, S118, and S119 to S123 in FIG. 9, the description thereof is omitted. Hereinafter, only steps S712 to S713, S717 to S718, S722 to S723, and S725 to S726 will be described. Further, when the flowchart shown in FIG. 32 is executed, instead of steps S101 to S110 of the flowchart shown in FIG. 8, steps S301 to S312 of the flowchart shown in FIG. 18 are executed.

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

[0243] On the other hand, 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 waits until the seventh predetermined time elapses (step S713). The seventh predetermined time is set, for example, to the time obtained by subtracting the time required for medium conveyance from the time required for image processing when a medium larger than the first size threshold is conveyed. Alternatively, the seventh predetermined time may be set to the maximum value of the stop time when a collision of the medium occurs in a prior experiment in which a medium smaller than the second size threshold is continuously conveyed while changing the stop time of the feed roller 112. Alternatively, the seventh predetermined time may be set to a time during which the feeding of the medium by the feed roller 112 can be delayed by an amount corresponding to the delay in discharging the medium by decelerating the discharge roller 123 in the process described later.

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

[0245] FIG. 33 is a graph for explaining the speed changes of the feed roller 112, the brake roller 113, and the conveyance roller 119 in the 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] In FIG. 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 conveyance roller 119. The horizontal axis of each of the graphs G91 to G93 indicates time, and the vertical axis indicates speed. Graphs G14 and G15 show the changes in the signal values of the fifth medium sensor 118 and the sixth medium sensor 121, and change in the same manner as the graphs G14 and G15 shown in FIG. 10. Also, times T1 to T6 indicate the same times as the 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 restart timing of the feeding by the feed roller 112 at time T4. When a medium with a large size is conveyed, the size of the input image becomes large, and it may take a long time for image processing. By delaying the restart timing of the feeding when a medium with a large size is conveyed, the control unit 151 can smoothly convey the medium without stopping it for image processing and obtain a good image. Also, as described above, generally, the shorter the length of the medium, the shorter the distance between the continuously conveyed media tends to be. By delaying the restart timing of the feeding when a medium with a small size is conveyed, the control unit 151 can suppress the continuously conveyed media from colliding with each other. Also, when a medium with a large size or a small size is conveyed, the control unit 151 reduces the speed of the discharge roller 123 in the process described later. In that case, by delaying the restart timing of the feeding, the control unit 151 can convey the medium at a stable speed.

[0248] After waiting until the leading edge of the medium passes the position of the second medium sensor 114 in step S716, the control unit 151 determines whether the size of the preceding medium is greater than the first size threshold and whether it is less than the second size threshold (step S717). If the size of the preceding medium is less than or equal to the first size threshold and greater than or equal to the second size threshold, the control unit 151 proceeds to step S719 without performing any special processing.

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

[0250] As shown in the graph G91 of FIG. 33, when the size of the preceding medium is greater than the first size threshold or less 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. As a result, the control unit 151 can smoothly convey a medium with a large size without stopping it for image processing and obtain a good image. Also, the control unit 151 can prevent a medium with a small size from colliding with other media when being conveyed. Further, the control unit 151 can convey the medium 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 the first size threshold and whether it is less than the second size threshold (step S722). If the size of the preceding medium is less than or equal to the first size threshold and greater than or equal to the second size threshold, the control unit 151 proceeds to step S724 without performing any special processing.

[0252] On the other hand, if the size of the preceding medium is greater than the first size threshold or less than the second size threshold, the control unit 151 controls the second motor 132 to reduce the speeds of the conveyance roller 119 and the discharge roller 123 (step S723).

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

[0254] As shown in the graph G93 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 reduces the speed of the discharge roller 123 between time T4 and time T5. When a medium with a large size is discharged, the leading end of the medium may exceed the leading end of the discharge table 104, and due to the weight of the leading end exceeding the discharge table 104, the medium may jump out of the discharge table 104. By reducing the speed of the discharge roller 123 when a medium with a large size is discharged, the control unit 151 can prevent the medium from jumping out of the discharge table 104. Further, when a plurality of media with different sizes are discharged, only the medium with a small size may be discharged vigorously, and the trailing ends of the media may not be aligned. By reducing the speed of the discharge roller 123 when a medium with a small size is discharged, the control unit 151 can improve the alignment of the media.

[0255] After waiting until the leading end of the medium passes the position of the fifth medium sensor 118 in step S724, the control unit 151 determines whether the size of the preceding medium is larger than the first size threshold and whether it is smaller than the second size threshold (step S725). When 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 proceeds to step S727 without performing any particular processing.

[0256] On the other hand, 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 waits until the seventh predetermined time elapses (step S727).

[0257] That is, after the fifth medium sensor 118 detects the tip of the medium in step S724, the control unit 151 increases the rotation speed of the feeding roller 112 in step S727. The control unit 151 delays the timing at which the rotation speed of the feeding roller 112 is increased when the size of the preceding medium is greater than the first size threshold value compared to the timing at which the rotation speed of the feeding roller 112 is increased when the size of the preceding medium is less than or equal to the first size threshold value. Similarly, the control unit 151 delays the timing at which the rotation speed of the feeding roller 112 is increased when the size of the preceding medium is smaller than the second size threshold value compared to the timing at which the rotation speed of the feeding roller 112 is increased when the size of the preceding medium is greater than or equal to the second size threshold value.

[0258] As shown in the graph G91 of FIG. 33, when the size of the preceding medium is greater than the first size threshold value or smaller than the second size threshold value, the control unit 151 delays the timing at which the speed of the feeding roller 112 is increased at time T5. Thereby, the control unit 151 can smoothly convey a medium having a large size without stopping it for image processing and acquire a good image. In addition, the control unit 151 can prevent a medium having a small size from colliding with other media when being conveyed. In addition, the control unit 151 can convey the medium at a stable speed.

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

[0260] Also, in step S712, S717, or S725, the control unit 151 may determine whether the size of the medium preceding the medium whose rear end 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 restart timing of the feeding by the feeding roller 112 when the size of the medium preceding the medium whose rear end has passed the position of the fifth medium sensor 118 is greater than the first size threshold, compared to the restart timing of the feeding by the feeding roller 112 when the size of the medium preceding the medium whose rear end has passed the position of the fifth medium sensor 118 is equal to or less than the first size threshold. Similarly, the control unit 151 delays the restart timing of the feeding by the feeding roller 112 when the size of the medium preceding the medium whose rear end has passed the position of the fifth medium sensor 118 is smaller than the second size threshold, compared to the restart timing of the feeding by the feeding roller 112 when the size of the medium preceding the medium whose rear end has passed the position of the fifth medium sensor 118 is equal to or greater than the second size threshold.

[0261] In these cases as well, the control unit 151 can smoothly convey the medium with a large size without stopping it for image processing and obtain a good image. Also, the control unit 151 can prevent the medium with a small size from colliding with other media when being conveyed.

[0262] Note that, as shown by the dotted line D8 of G92 in FIG. 33, the control unit 151 may once stop the brake roller 113 while the rear end of the medium is passing through the nip region between the feeding roller 112 and the brake roller 113, and then restart the rotation of the brake roller 113 after the rear end has passed through that nip region. Or, as shown by the dotted line D9 of G92, the control unit 151 may reduce the speed of the brake roller 113 while the rear end of the medium is passing through that nip region, and then increase the speed of the brake roller 113 after the rear end has passed through that nip region to return to the final speed U3a. Thereby, the control unit 151 can prevent the leading end of the subsequent medium from curling up and prevent the occurrence of media jams.

[0263] Further, the control unit 151 may start the rotation of the brake roller 113 before the rotation of the feed roller 112. Thereby, the control unit 151 can suppress a plurality of media placed on the mounting table 103 from avalanching between the feed roller 112 and the brake roller 113, and can suppress the occurrence of double feeding of the media.

[0264] As described in detail above, even when the medium conveyance device changes the speed of the discharge roller 123 based on the size of the medium, it has become possible to better control the feeding of the medium.

[0265] Note that even when the medium conveyance device changes the speed of the discharge roller 123, the brake roller 113 may be driven by either the first motor or the second motor. In that 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. Further, the control unit 151 may 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. Further, the medium conveyance device has 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 conveyance roller 119 by controlling the driving force interruption mechanism.

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

[0267] The flowcharts shown in FIGS. 34 and 35 are executed instead of the flowcharts shown in FIGS. 8 and 9. Since the processes of steps S801 to S805, S810 to S821, and S823 to S826 in FIGS. 34 and 35 are the same as the processes of steps S101 to S105, S107 to SS118, and S120 to S123 in FIGS. 8 and 9, the description thereof is omitted. Hereinafter, only steps S806 to S809 and S822 will be described.

[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 conveyance roller 119 in the high-speed mode.

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

[0271] As shown by the solid line L10 in the graph G101, the control unit 151 stops the feed roller 112 at time T2. Or, as shown by the dotted line D10 in the 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 conveyed medium in the same manner as the process of step S307 in FIG. 18 (step S807).

[0273] Next, the control unit 151 sets and changes the speed of the conveyance roller 119 based on the detected thickness of the medium (step S808). The speed of the conveyance roller 119 is set within a range that is equal to or higher than the initial speed W1 and equal to or lower than the final speed W3a. In particular, the control unit 151 sets the rotational speed of the conveyance roller 119 such that the speed of the conveyance roller 119 is equal to or higher than the speed of the feed roller 112. Thereby, the control unit 151 can suppress the medium from being pushed by the feed roller 112 and bending between the feed roller 112 and the conveyance roller 119, and prevent a jam of the medium from occurring.

[0274] Also, the speed of the conveyance roller 119 is set such that the smaller the thickness of the medium, the higher the speed, and the larger the thickness of the medium, the lower the speed. Note that the speed of the conveyance roller 119 may be set such that the larger the thickness of the medium, the higher the speed, and the smaller the thickness of the medium, the lower the speed. The medium conveyance device 100 stores in advance in the storage device 140 a table defining the relationship between the thickness of the medium and the speed of the conveyance roller 119. The control unit 151 refers to the table stored in the storage device 140 and specifies the speed corresponding to the detected thickness.

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

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

[0277] Next, the control unit 151 resumes 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] As shown in the graph G101 of FIG. 36, after setting the speed of the feed roller 112 to the final speed V3a, the control unit 151 resumes the 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 the 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 end of the medium passes through 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 conveyance roller 119 based on the thickness of the medium. After that, the control unit 151 resumes the rotation of the feed roller 112 or accelerates the feed roller 112. When the thickness of the medium is detected during the feeding of the medium, a detection error may occur due to shaking of the medium or the like. The control unit 151 can detect the thickness of the medium with higher accuracy by detecting the thickness of the medium while the feed roller 112 is temporarily stopped or decelerated.

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

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

[0282] As described in detail above, even when the medium conveyance device changes the speed of the conveyance roller 119 based on the thickness of the medium, it has become possible to better control the feeding of the medium.

[0283] In addition, even when the medium conveyance device changes the speed of the conveyance 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 that 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 conveyance roller 119. Also, the control unit 151 may 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. Further, the medium conveyance device has a driving force interruption mechanism such as an electromagnetic clutch between the conveyance roller 119 and the second motor, and the control unit 151 may change the speed of the conveyance roller 119 by controlling the driving force interruption mechanism.

[0284] FIG. 37 is a diagram showing a schematic configuration of a processing circuit 250 in a medium conveyance device according to another embodiment. The processing circuit 250 is used in place of the processing circuit 150 of the medium conveyance 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, a determination circuit 252, and the like. Note that each of these units may be configured by 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. Further, the control circuit 251 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. Also, the control circuit 251 receives the 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 respective information, 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 functions 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 the skew of the medium has occurred based on the received respective signals, and outputs the determination result to the control circuit 251.

[0287] As described in detail above, even when the processing circuit 250 is used, the medium conveyance device can control the feeding of the medium better.

[0288] Although the preferred embodiments have been described above, the embodiments are not limited to these. For example, the medium conveyance device 100 may have a thin paper conveyance mode for conveying thin paper as the medium and a normal mode for conveying other media. In that case, the control unit 151 sets the rotational 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 conveyance mode. Thereby, since the thin paper is conveyed at a lower speed than other media, the control unit 151 can suppress damage to the thin paper caused by conveyance.

[0289] Also, similar to each of the above-described embodiments, the control unit 151 sets the rotational speed of the feeding roller 112 and the rotational speed of the conveying roller 119 such that the speed of the conveying roller 119 is greater than the speed of the feeding roller 112 in the normal mode and the thin paper conveying mode. Thereby, the control unit 151 can suppress the medium from being pushed by the feeding roller 112 and being bent between the feeding roller 112 and the conveying roller 119, and the occurrence of medium jams in the normal mode and the thin paper conveying mode. Further, the control unit 151 sets the rotational speed of the feeding roller 112 and the rotational speed of the conveying roller 119 such that the ratio of the speed of the feeding roller 112 to the speed of the conveying roller 119 in the normal mode is smaller than the ratio of the speed of the feeding roller 112 to the speed of the conveying roller 119 in the thin paper conveying mode. Thereby, in the thin paper conveying mode, the speed of the feeding roller 112 approaches the speed of the conveying roller 119, and the thin paper is conveyed more stably.

[0290] Also, the medium conveying device may have a separation mode for feeding while separating the medium and a non-separation mode for feeding without separating the medium. In that case, when operating in the separation mode, the control unit 151 executes each of the above-described medium reading processes. 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 rotates along with the feeding roller 112. In that case, the control unit 151 controls the second electromagnetic clutch 134 to change the magnitude of the torque applied to the brake roller 113. Thereby, the control unit 151 can appropriately feed the medium in both the separation mode and the non-separation mode.

[0291] Also, the medium conveying device may not have a high-speed mode, a medium-speed mode, and a low-speed mode, and may fixedly operate in the high-speed mode.

[0292] Also, in the determination of using the fifth medium sensor 118, the control unit 151 may use the second medium sensor 114 instead of the fifth medium sensor 118. That is, in each of the above-described processes, the control unit 151 may execute each process that is executed when the leading end or the trailing end of the medium passes through the position of the fifth medium sensor 118 when the leading end or the trailing end of the medium passes through the position of the second medium sensor 114.

[0293] Further, 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 the information processing device. Alternatively, the size or thickness of the medium may be specified from the medium type (such as paper, postcard, business card, etc.) set by the user using the operation device 105 or the information processing device. In that case, the medium conveyance device stores in advance in the storage device 140 a table defining the relationship between the medium type and the size or thickness of the medium. The control unit 151 refers to the table stored in the storage device 140 to specify the size or thickness of the medium to be conveyed. Regarding the above-described embodiments, the following additional remarks are disclosed. (Supplementary Note 1) A mounting table for mounting a medium; A feeding roller that separates and sequentially feeds the medium placed on the mounting table; A motor that drives the feeding roller; A conveying roller that conveys the medium fed by the feeding roller; A sensor that is disposed between the feeding roller and the conveying roller and detects the medium; During the separation period from the start of feeding the medium by the feeding roller until the sensor detects the leading end 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 speed, and when feeding the second and subsequent media, the motor is controlled to rotate the feeding roller at a first speed and then at a second speed higher than the first speed; A medium conveyance device, characterized by comprising the above. (Supplementary Note 2) The control unit controls the motor to continue rotating the feeding roller while reducing the rotation speed of the feeding roller when the leading end of the medium passes through the conveying roller, according to the medium conveying device described in Supplementary Note 1. (Supplementary Note 3) The control unit reduces the rotation speed of the conveying roller when the trailing end of the medium passes through the sensor, according to the medium conveying device described in any one of Supplementary Notes 1 to 2. (Supplementary Note 4) Further includes an imaging unit that is disposed downstream of the conveying roller in the medium conveying direction and images the medium conveyed by the conveying roller. The control unit increases the rotation speed of the conveying roller when the trailing end of the medium passes through the imaging position of the imaging unit, according to the medium conveying device described in any one of Supplementary Notes 1 to 3. (Supplementary Note 5) The control unit increases the rotation speed of the feeding roller when the trailing end of the medium passes through the conveying roller, according to the medium conveying device described in any one of Supplementary Notes 1 to 4. (Supplementary Note 6) The control unit detects the size of the medium, sets the second speed when the size of the preceding medium is less than or equal to the size threshold to a lower speed than the second speed when the size of the preceding medium is greater than the size threshold, according to the medium conveying device described in any one of Supplementary Notes 1 to 5. (Supplementary Note 7) The control unit detects the thickness of the medium, sets the second speed when the thickness of the preceding medium is less than or equal to the thickness threshold to a lower speed than the second speed when the thickness of the preceding medium is greater than the thickness threshold, according to the medium conveying device described in any one of Supplementary Notes 1 to 6. (Supplementary Note 8) Further includes a discharge roller that discharges the medium conveyed by the conveying roller. The control unit detects the size of the medium, The medium conveyance device according to any one of Appendices 1 to 7, wherein when the size of the medium is larger than a first size threshold value, the rotation speed of the discharge roller is set to a speed lower than the rotation speed of the discharge roller when the size of the medium is equal to or less than the first size threshold value. (Appendix 9) further comprising a discharge roller that discharges the medium conveyed by the conveyance roller, the control unit, detects the size of the medium, The medium conveyance device according to any one of Appendices 1 to 7, wherein when the size of the medium is smaller than a second size threshold value, the rotation speed of the discharge roller is set to a speed lower than the rotation speed of the discharge roller when the size of the medium is equal to or greater than the second size threshold value. (Appendix 10) the control unit, detects the size of the medium, after the sensor detects the leading end of the medium, increases the rotation speed of the feed roller, The medium conveyance device according to any one of Appendices 1 to 9, wherein the timing for increasing the rotation speed of the feed roller when the size of the preceding medium is larger than a first size threshold value is delayed compared to the timing for increasing the rotation speed of the feed roller when the size of the preceding medium is equal to or less than the first size threshold value. (Appendix 11) the control unit, detects the size of the medium, stops the feed roller when the leading end of the medium passes through the conveyance roller, and resumes feeding by the feed roller after the trailing end of the medium passes through a predetermined position, The medium conveyance device according to any one of Appendices 1 to 10, wherein the timing for resuming feeding by the feed roller when the trailing end of the medium that has passed through the predetermined position or the size of the medium preceding the medium is larger than a first size threshold value is delayed compared to the timing for resuming feeding by the feed roller when the trailing end of the medium that has passed through the predetermined position or the size of the medium preceding the medium is equal to or less than the first size threshold value. (Appendix 12) the control unit, detects the thickness of the medium, The medium conveying device according to any one of appendices 1 to 11, which sets the rotational speed of the conveying roller based on the thickness of the medium. (Appendix 13) When the leading end of the medium passes through the sensor, the control unit temporarily stops or decelerates the feeding roller, detects the thickness of the medium, and sets the rotational speed of the conveying roller, and then resumes the rotation of the feeding roller or accelerates the feeding roller. The medium conveying device according to appendix 12. (Appendix 14) The medium conveying device according to any one of appendices 1 to 13, wherein the control unit sets the rotational speed of the conveying roller so that the surface moving speed of the conveying roller is equal to or higher than the surface moving speed of the feeding roller. (Appendix 15) The medium conveying device has a normal mode and a thin paper conveying mode. The control unit sets the rotational speed of the feeding roller and the rotational speed of the conveying roller so that the ratio of the surface moving speed of the feeding roller to the surface moving speed of the conveying roller in the normal mode is smaller than the ratio of the surface moving speed of the feeding roller to the surface moving speed of the conveying roller in the thin paper conveying mode, and the surface moving speed of the feeding roller in the normal mode is larger than the surface moving speed of the feeding roller in the thin paper conveying mode. The medium conveying device according to appendix 14. (Appendix 16) When the time from when the trailing end of the preceding medium passes through the first position to when the leading end of the subsequent medium passes through the second position is equal to or less than a predetermined time, the control unit temporarily stops or decelerates the feeding roller. The medium conveying device according to any one of appendices 1 to 15. (Appendix 17) When the leading end of the subsequent medium passes through the sensor following the preceding medium, the control unit temporarily stops or decelerates the feeding roller, and determines the timing to resume the rotation of the feeding roller or the timing to accelerate the feeding roller based on the time from when the trailing end of the preceding medium passes through the first position to when the leading end of the subsequent medium passes through the second position. The medium conveying device according to any one of appendices 1 to 16.

Explanation of reference numerals

[0294] 100 Media conveying device, 103 Mounting table, 112 Feeding roller, 113 Brake roller, 114 Second media sensor, 118 Fifth media 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 placement table for placing a medium, A feeding roller that separates the media placed on the placement table and feeds them sequentially, A conveying roller that conveys the media fed by the feeding roller, A motor that drives the feeding roller, A sensor that is arranged downstream of the feeding roller in the medium conveyance direction and detects the medium, During the separation period from the start of feeding the medium by the feeding roller until the sensor detects the leading edge of the medium, when feeding the first medium among the media placed on the placement table, the motor is controlled to rotate the feeding roller at a constant predetermined speed, and when feeding the second and subsequent media, 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, and a control unit, When the leading edge of the medium passes through the conveying roller, the control unit controls the motor to continue rotating the feeding roller while reducing the rotation speed of the feeding roller, A medium conveyance device characterized by comprising the above.

2. A placement table for placing a medium, A feeding roller that separates the media placed on the placement table and feeds them sequentially, A motor that drives the feeding roller, A sensor that is arranged downstream of the feeding roller in the medium conveyance direction and detects the medium, During the separation period from the start of feeding the medium by the feeding roller until the sensor detects the leading edge of the medium, when feeding the first medium among the media placed on the placement table, the motor is controlled to rotate the feeding roller at a constant predetermined speed, and when feeding the second and subsequent media, 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, and a control unit, The control unit sets the second speed when the size of the preceding medium is less than or equal to the size threshold to a speed lower than the second speed when the size of the preceding medium is greater than the size threshold, A medium conveyance device characterized by the above.

3. A medium conveyance device having a normal mode and a thin paper conveyance mode, A placement table for placing a medium, A feeding roller that separates the media placed on the placement table and feeds them sequentially, A conveying roller that conveys the media fed by the feeding roller, A motor that drives the feeding 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 media conveying device having a mounting table for placing media thereon, a feed roller for separating and sequentially feeding the media placed on the mounting table, a motor for driving the feed roller, and a sensor for detecting the media, disposed downstream of the feed roller in the media conveying direction, 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