Medium conveyance apparatus, medium conveyance method and control program

Abstract

To provide a medium conveyance apparatus, a medium conveyance method and a control program which can feed a medium in a more timely manner.SOLUTION: A medium conveyance apparatus comprises: a feed roller for feeding a medium; a pair of conveyance rollers which are arranged downstream of the feed roller in a medium conveyance direction; a detection unit which is arranged downstream of the pair of conveyance rollers in the medium conveyance direction; and a control unit, when a tip of a medium passes through the detection unit, and then it is conveyed in a prescribed amount, which starts the feed of the next medium.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a medium conveyance device, a control method, and a control program.

Background Art

[0002] Generally, a medium conveyance device such as a scanner that sequentially feeds and conveys a plurality of media starts feeding the next medium before the reading and conveyance of each medium are completed so that the reading and conveyance of the plurality of media can be completed in a shorter time.

[0003] An automatic paper feeding device that estimates the maximum paper length from the detection state of a paper length sensor disposed on a paper tray unit to detect the paper length is disclosed (see Patent Document 1). This automatic paper feeding device starts the paper feeding operation for the next paper when it is determined that the rear end of the paper has passed the position of the paper feeding roller that feeds the paper based on the estimated maximum paper length.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a medium conveyance device, it is required to feed the medium at a more appropriate timing.

[0006] An object of the present invention is to provide a medium conveyance device, a medium conveyance method, and a control program capable of feeding a medium at a more appropriate timing.

Means for Solving the Problems

[0007] A media conveyance device according to an aspect of the present invention includes a feeding roller that feeds a media, a pair of conveyance rollers disposed downstream of the feeding roller in the media conveyance direction, a detection unit disposed downstream of the pair of conveyance rollers in the media conveyance direction, and a control unit that starts feeding the next media when the leading end of the media has passed through the detection unit and the media has been conveyed a predetermined amount.

[0008] A media conveyance method according to an aspect of the present invention feeds a media by a feeding roller, and starts feeding the next media when the leading end of the media has passed through a detection unit disposed downstream of a pair of conveyance rollers disposed downstream of the feeding roller in the media conveyance direction and the media has been conveyed a predetermined amount.

[0009] A control program according to an aspect of the present invention is a control program for a media conveyance device including a feeding roller that feeds a media, a pair of conveyance rollers disposed downstream of the feeding roller in the media conveyance direction, and a detection unit disposed downstream of the pair of conveyance rollers in the media conveyance direction, and causes the media conveyance device to start feeding the next media when the leading end of the media has passed through the detection unit and the media has been conveyed a predetermined amount.

Advantages of the Invention

[0010] According to the present invention, the media conveyance device, the media conveyance method, and the control program can feed the media at a more appropriate timing.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Embodiments for Carrying Out the Invention

[0012] Hereinafter, a medium conveyance device, a medium conveyance method, and a control program according to one aspect of the present invention will be described with reference to the drawings. However, note 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.

[0013] FIG. 1 is a perspective view showing a medium conveyance device configured as an image scanner.

[0014] The medium conveyance device 100 conveys and images a medium that is a document. The medium is paper, cardboard, card, booklet, passport, or the like. The medium conveyance device 100 may be a facsimile machine, a copier, a printer multifunction peripheral (MFP), or the like. Note that the medium to be conveyed may not be a document but a printing object or the like, and the medium conveyance device 100 may be a printer or the like.

[0015] In FIG. 1, arrow A1 indicates the medium conveyance direction, and arrow A2 indicates the width direction orthogonal to the medium conveyance direction. Hereinafter, "upstream" refers to the upstream in the medium conveyance direction A1, and "downstream" refers to the downstream in the medium conveyance direction A1.

[0016] The medium 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.

[0017] The upper housing 102 is disposed at a position covering the upper surface of the medium conveyance device 100 and is engaged with the lower housing 101 by a hinge so as to be openable and closable during media jamming, cleaning inside the medium conveyance device 100, etc.

[0018] 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. The discharge table 104 may be provided so as to be engaged with the lower housing 101.

[0019] 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 the 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), etc. and an interface circuit that outputs image data to the display, and displays the image data on the display.

[0020] FIG. 2 is a diagram for explaining the conveyance path inside the medium conveyance device.

[0021] The conveyance path inside the medium conveyance device 100 includes a placement sensor 111, a feed roller 112, a separation roller 113, a first conveyance roller 114, a second conveyance roller 115, a medium sensor 116, an imaging device 117, a third conveyance roller 118, a fourth conveyance roller 119, and the like.

[0022] The first conveying roller 114 and the second conveying roller 115, or the third conveying roller 118 and the fourth conveying roller 119 are an example of a pair of conveying rollers. The number of each of the feeding roller 112, the separating roller 113, the first conveying roller 114, the second conveying roller 115, the third conveying roller 118 and / or the fourth conveying roller 119 is not limited to one, and may be plural. In that case, the plurality of feeding rollers 112, separating rollers 113, first conveying rollers 114, second conveying rollers 115, third conveying rollers 118 and / or fourth conveying rollers 119 are arranged side by side at intervals in the width direction A2.

[0023] The medium conveying device 100 has a so-called straight path. The upper surface of the lower housing 101 forms a lower guide 101a of the medium conveying path, and the lower surface of the upper housing 102 forms an upper guide 102a of the medium conveying path.

[0024] The placement sensor 111 is arranged upstream of the feeding roller 112 and the separating roller 113, and detects whether a medium is placed on the placement table 103. The placement sensor 111 is a contact detection sensor including an arm movably provided by contacting the medium, and a light emitter and a light receiver provided to face each other with the arm therebetween. The light emitter is an LED (Light Emitting Diode) or the like, and irradiates light toward the light receiver. On the other hand, the light receiver is a photodiode or the like, and receives the light irradiated by the light emitter. The arm blocks the light irradiated from the light emitter to the light receiver in either a state of being in contact with the medium or a state of not being in contact with the medium, and does not block the light irradiated from the light emitter to the light receiver in the other state. The placement sensor 111 generates and outputs a placement signal whose signal value changes between a state where the arm is in contact with the medium and a state where the arm is not in contact with the medium. That is, the signal value of the placement signal changes between a state where a medium is placed on the placement table 103 and a state where it is not placed.

[0025] As the placement sensor 111, any sensor capable of detecting the presence or absence of a medium, such as an optical detection sensor including a light emitter that irradiates light toward the placement table 103 or from the placement table 103, and a light receiver that detects the light irradiated by the light emitter and reflected by the medium placed on the placement table 103, may be used.

[0026] The feed roller 112 is provided on the lower housing 101 and sequentially separates and feeds the medium placed on the placement table 103 from below. The separation roller 113 is a so-called brake roller or retard roller, is provided on the upper housing 102, and is arranged to face the feed roller 112. The separation roller 113 is provided so as to be rotatable or stoppable in the direction A4 opposite to the medium feed direction. Note that a separation pad may be used instead of the separation roller 113. The feed roller 112 and the separation roller 113 function as a separation unit for separating the medium.

[0027] The first conveyance roller 114 and the second conveyance roller 115 are arranged opposite to each other on the downstream side of the feed roller 112 in the medium conveyance direction A1 and convey the medium fed by the feed roller 112 and the separation roller 113 to the imaging device 117.

[0028] The medium sensor 116 is an example of a detection unit and detects the medium conveyed to its arrangement position. The medium sensor 116 is arranged on the downstream side of the first conveyance roller 114 and the second conveyance roller 115 and on the upstream side of the imaging device 117 in the medium conveyance direction A1. Note that the medium sensor 116 may be arranged on the downstream side of the imaging device 117 and on the upstream side of the third conveyance roller 118 and the fourth conveyance roller 119 in the medium conveyance direction A1. Further, the medium sensor 116 may be arranged on the downstream side of the third conveyance roller 118 and the fourth conveyance roller 119 in the medium conveyance direction A1.

[0029] The media sensor 116 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, for example, an LED, and irradiates light toward the media conveyance path. On the other hand, the light receiver is, for example, a photodiode, and detects (receives) the light irradiated by the light emitter and guided by the light guide pipe. When a media exists at a position facing at least one of the light emitter and the light receiver, the light irradiated from the light emitter is blocked by the media, so the light receiver does not detect the light irradiated from the light emitter. The media sensor 116 generates and outputs a media signal whose signal value changes between a state where a media exists and a state where a media does not exist at the position of the media sensor 116 based on the intensity of the light received by the light receiver.

[0030] As described above, the media sensor 116 is a light detection sensor that irradiates light toward the media conveyance path and detects the received light. Generally, in a contact detection sensor including an arm or the like that contacts the media, the arm may wear due to contact with the media. By using a light detection sensor as the media sensor 116, the media conveyance device 100 can achieve a longer service life of components compared to the case of using a contact detection sensor. Further, in a contact detection sensor, chattering may occur when the arm contacts the media. By using a light detection sensor as the media sensor 116, the media conveyance device 100 can detect the media earlier and more stably compared to the case of using a contact detection sensor.

[0031] Note that in the media sensor 116, a reflection member such as a mirror may be used instead of the light guide pipe. Also, in the media sensor 116, the light emitter and the light receiver may be provided to face each other with the media conveyance path therebetween.

[0032] Further, the media sensor 116 may detect the presence of the media by an ultrasonic sensor including an ultrasonic transmitter and an ultrasonic receiver that are arranged to face each other across the conveyance path near the conveyance path of the media. The ultrasonic transmitter outputs (transmits) ultrasonic waves. The ultrasonic receiver receives the ultrasonic waves output (transmitted) from the ultrasonic transmitter and passing through the media, and generates and outputs a media signal according to the intensity or phase of the received ultrasonic waves. In that case, the media conveyance device 100 may detect the presence or absence of the media and detect double feeding of the media using the ultrasonic sensor. By using the ultrasonic sensor as the detection unit, the media conveyance device 100 can appropriately determine the timing to start feeding the media without using a dedicated sensor for determining the timing to start feeding the media.

[0033] Further, the media sensor 116 may detect the presence of the media by a contact detection sensor including an arm movably provided by contacting the media and a light emitter and a light receiver provided to face each other across the arm. By using the contact detection sensor as the detection unit, the media conveyance device 100 can detect the media with high accuracy without being affected by dirt (such as paper dust, roller wear powder, and dust) around the light emitter or the light receiver.

[0034] Further, the media sensor 116 may detect the presence of the media by an encoder including a disk formed with a number of slits (light transmission holes) and provided to rotate according to the fed media, and a light emitter and a light receiver provided to face each other across the disk. The light emitter is an LED or the like and irradiates light toward the disk (light receiver). The light receiver is a photodiode or the like and receives the light irradiated by the light emitter through the disk. The light receiver generates a media signal indicating whether or not it changes between a state where a slit exists between the light emitter and the light receiver and a state where the disk blocks the light without a slit within a predetermined period. By using the contact detection sensor as the detection unit, the media conveyance device 100 can detect the media with high accuracy without being affected by dirt (such as paper dust, roller wear powder, and dust) around the light emitter or the light receiver.

[0035] The imaging device 117 is arranged on the downstream side of the first conveyance roller 114 and the second conveyance roller 115, and images the medium conveyed by the first conveyance roller 114 and the second conveyance roller 115. The imaging device 117 includes a first imaging device 117a and a second imaging device 117b that are arranged to face each other across the medium conveyance path.

[0036] The first imaging device 117a has a line sensor (imaging sensor) of a CIS (Contact Image Sensor) of an equal magnification optical system type having an imaging element made of CMOS (Complementary Metal Oxide Semiconductor) linearly arranged in the main scanning direction. The first imaging device 117a 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 117a images the surface of the conveyed medium according to the control from the processing circuit described later. The first imaging device 117a sequentially generates and outputs line images obtained by imaging the region facing the line sensor of the conveyed medium at regular intervals.

[0037] Similarly, the second imaging device 117b has a line sensor (imaging sensor) of a CIS of an equal magnification optical system type having an imaging element made of CMOS linearly arranged in the main scanning direction. The second imaging device 117b 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 second imaging device 117b images the back surface of the conveyed medium according to the control from the processing circuit described later. The second imaging device 117b sequentially generates and outputs line images obtained by imaging the region facing the line sensor of the conveyed medium at regular intervals.

[0038] Note that the medium conveyance device 100 may be arranged with only one of the first imaging device 117a and the second imaging device 117b to read only one side of the medium. Further, instead of the line sensor of the 1:1 optical system type CIS including an imaging element using a CMOS, a line sensor (imaging sensor) of the 1:1 optical system type CIS including an imaging element using a CCD (Charge Coupled Device) may be used. Further, a line sensor (imaging sensor) of the reduced optical system type including an imaging element using a CMOS or a CCD may be used.

[0039] The third conveyance roller 118 and the fourth conveyance roller 119 are arranged to face each other on the downstream side of the imaging device 117, convey the medium conveyed by the first conveyance roller 114 and the second conveyance roller 115 and imaged by the imaging device 117, and discharge it to the discharge table 104.

[0040] 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 A3 in FIG. 2, that is, the medium feeding direction. The medium conveyance device 100 has, as a feeding mode, a separation mode of feeding the medium while separating it and a non-separation mode of feeding the medium without separating it. The feeding mode is set by the user using the operation device 105 or an information processing device communicatively connected to the medium conveyance device 100. When the feeding mode is set to the separation mode, the separation roller 113 rotates or stops in the direction of arrow A4, that is, the direction opposite to the medium feeding direction, during the conveyance of the medium. Thereby, the conveyance of the medium other than the separated medium is restricted (prevention of double feeding). On the other hand, when the feeding mode is set to the non-separation mode, the separation roller 113 rotates in the direction opposite to arrow A4, that is, in the medium feeding direction.

[0041] The medium is fed between the first conveying roller 114 and the second conveying roller 115 while being guided by the lower guide 101a and the upper guide 102a. The medium is fed between the first imaging device 117a and the second imaging device 117b by the first conveying roller 114 and the second conveying roller 115 rotating in the directions of arrow A5 and arrow A6 respectively. The medium read by the imaging device 117 is discharged onto the discharge table 104 by the third conveying roller 118 and the fourth conveying roller 119 rotating in the directions of arrow A7 and arrow A8 respectively.

[0042] Figure 3 is a block diagram showing a schematic configuration of the medium conveying device.

[0043] In addition to the above-described configuration, the medium conveying device 100 further includes a motor 131, an interface device 132, a storage device 140, a processing circuit 150, and the like.

[0044] The motor 131 includes one or a plurality of motors, and rotates the feed roller 112, the separation roller 113, the first conveying roller 114, the second conveying roller 115, the third conveying roller 118, and / or the fourth conveying roller 119 according to a control signal from the processing circuit 150 to convey the medium. The motor 131 may include separate motors that independently rotate the feed roller 112, the separation roller 113, the first conveying roller 114, the second conveying roller 115, the third conveying roller 118, and / or the fourth conveying roller 119. Note that either one of the first conveying roller 114 and the second conveying roller 115 may be a driven roller that rotates following the other roller. Also, either one of the third conveying roller 118 and the fourth conveying roller 119 may be a driven roller that rotates following the other roller.

[0045] The interface device 132 has an interface circuit conforming to a serial bus such as USB, etc., and is electrically connected to an information processing device (e.g., a personal computer, a mobile information terminal, etc.) not shown in the figure to transmit and receive an input image and various kinds of information. Further, instead of the interface device 132, a communication unit having an antenna for transmitting and receiving wireless signals and a wireless communication interface device for transmitting and receiving signals through a wireless communication line according to a predetermined communication protocol may be used. The predetermined communication protocol is, for example, a wireless LAN (Local Area Network). 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, etc.

[0046] The storage device 140 has a memory device such as a RAM (Random Access Memory), a ROM (Read Only Memory), etc., a fixed disk device such as a hard disk, or a portable storage device such as a flexible disk, an optical disk, etc. Further, various computer programs, databases, tables, etc. used for various processes of the medium conveyance device 100 are stored in the storage device 140. The computer program may be installed in the storage device 140 from a computer-readable portable recording medium using a known setup program, etc. The portable recording medium is, for example, a CD-ROM (compact disc read only memory), a DVD-ROM (digital versatile disc read only memory), etc. Further, the computer program may be distributed from a server, etc. and installed in the storage device 140.

[0047] The processing circuit 150 operates based on a program stored in advance in the storage device 140. The processing circuit is, for example, a CPU (Central Processing Unit). As the processing circuit 150, a DSP (digital signal processor), LSI (large scale integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), etc. may be used.

[0048] The processing circuit 150 is connected to an operation device 105, a display device 106, a placement sensor 111, a media sensor 116, an imaging device 117, a motor 131, an interface device 132, a storage device 140, etc., and controls these respective parts. The processing circuit 150 performs drive control of the motor 131, imaging control of the imaging device 117, etc. based on each signal received from each sensor, acquires an input image from the imaging device 117, and transmits it to an information processing device via the interface device 132.

[0049] FIG. 4 is a diagram showing a schematic configuration of a storage device and a processing circuit.

[0050] As shown in FIG. 4, a control program 141, a length detection program 142, a reception program 143, etc. are stored in the storage device 140. These respective programs are functional modules 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, a length detection unit 152, and a reception unit 153.

[0051] FIG. 5 is a flowchart showing an example of the operation of the media conveyance process of the media conveyance device.

[0052] Next, while referring to the flowchart shown in FIG. 5, an example of the operation of the media conveyance process of the media conveyance device 100 will be described. Note that the operation flow described below is mainly executed by the processing circuit 150 in cooperation with each element of the media conveyance device 100 based on a program stored in the storage device 140 in advance.

[0053] 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 it receives an operation signal instructing the reading of the medium from the operation device 105 or the interface device 132 (step S101).

[0054] Next, the control unit 151 acquires a placement signal from the placement sensor 111, and based on the acquired placement signal, determines whether a medium is placed on the placement table 103 (step S102). If no medium is placed on the placement table 103, the control unit 151 ends the series of steps.

[0055] On the other hand, if a medium is placed on the placement table 103, the control unit 151 drives the motor 131 to rotate the feed roller 112, the separation roller 113, the first conveyance roller 114, the second conveyance roller 115, the third conveyance roller 118, and / or the fourth conveyance roller 119 to feed and convey the medium (step S103).

[0056] Next, the control unit 151 waits until the leading end of the medium passes through the medium sensor 116 (step S104). The control unit 151 periodically acquires a medium signal from the medium sensor 116, and determines that the leading end of the medium has passed through the medium sensor 116 when the signal value of the medium signal changes from a value indicating the absence of the medium to a value indicating the presence of the medium.

[0057] When the leading edge of the medium passes through the medium sensor 116, the control unit 151 determines that the leading edge of the medium has passed the positions of the first conveyance roller 114 and the second conveyance roller 115, and controls the motor 131 to stop the feeding roller 112 (step S105). Thereafter, the medium is conveyed by the first conveyance roller 114, the second conveyance roller 115, the third conveyance roller 118, and / or the fourth conveyance roller 119. By stopping the feeding roller 112, the medium conveyance device 100 can suppress the occurrence of medium jamming due to the medium being pushed by the feeding roller 112 and the medium being bent, and the occurrence of double feeding of the medium due to the next medium being fed by the feeding roller 112.

[0058] Next, the control unit 151 determines whether the size flag is set to the large size or the non-large size (step S106). The size flag is set to the non-large size at the start of the medium conveyance process. Also, in the process described later, the size flag is set to the large size when it is determined that the length of the fed medium is greater than the threshold value, and is set to the non-large size when it is determined that the length of the fed medium is less than or equal to the threshold value. The threshold value is set, for example, to the size of the medium (e.g., A4 size) estimated to be the most frequently conveyed in the medium conveyance device 100. That is, the large size is set to a size larger than the size of the medium (e.g., A4 size) estimated to be the most frequently conveyed in the medium conveyance device 100. The size flag may be set by comparing the paper length detected by a known means such as a paper length sensor that detects the paper length arranged on the mounting table 103 with the threshold value. The size flag may also be set based on an input from a user who specifies the paper type using the operation device 105 or the information processing device.

[0059] When the size flag is set to a non-large size, the control unit 151 determines whether or not a predetermined amount of the medium has been conveyed after the leading end of the medium has passed through the medium sensor 116 (step S107). The predetermined amount is set, for example, to the driving amount of the motor that drives the feed roller 112 for moving the medium by the first distance. The predetermined amount may be set to the rotation amount of the feed roller 112 for moving the medium by the first distance. The predetermined amount may be set to the driving time of the motor that drives the feed roller 112 for moving the medium by the first distance. The control unit 151 determines that the medium has been conveyed by the predetermined amount when the motor is driven by the amount corresponding to the conveyance of the predetermined amount of the medium after determining in step S104 that the leading end of the medium has passed through the medium sensor 116.

[0060] FIG. 6(A) is a schematic diagram for explaining the first distance.

[0061] As shown in FIG. 6(A), the first distance D1 is the distance obtained by subtracting the second distance D2 from the length L1 of the medium M1 of a specific size in the medium conveyance direction A1. The second distance D2 is the distance from the arrangement position P1 of the medium sensor 116 to a specific position P2 between the feed roller 112 and the separation roller 113 and between the first conveyance roller 114 and the second conveyance roller 115. The specific size is set, for example, to the size of the medium (e.g., A4 portrait size) that is estimated to be the most frequently conveyed in the medium conveyance device 100. That is, when the leading end of the medium M1 has passed through the medium sensor 116 and the medium M1 has moved by the first distance D1, the trailing end of the medium M1 has passed through the feed roller 112 and the separation roller 113 (separation unit).

[0062] When the leading end of the medium has passed through the medium sensor 116 and the medium has been conveyed by a predetermined amount, the control unit 151 starts feeding the next medium in the processes described below. As a result, the medium conveying device 100 can suppress the occurrence of double feeding of the medium by starting the feeding of the next medium M2 before the trailing end of the fed medium M1 passes through the feeding roller 112 and the separating roller 113 (separating unit). Further, the medium conveying device 100 can start feeding the next medium M2 without waiting for the trailing end of the medium M1 to pass through the medium sensor 116, and can feed a plurality of media in a short time.

[0063] When the control unit 151 determines that the medium has been conveyed by a predetermined amount after the leading end of the medium has passed through the medium sensor 116, the process proceeds to step S111.

[0064] On the other hand, when the control unit 151 determines that the medium has not yet been conveyed by a predetermined amount after the leading end of the medium has passed through the medium sensor 116, the control unit 151 determines whether the trailing end of the medium has passed through the medium sensor 116 (step S108). The control unit 151 periodically acquires a medium signal from the medium sensor 116, and determines that the trailing end of the medium has passed through the medium sensor 116 when the signal value of the medium signal changes from a value indicating the presence of the medium to a value indicating the absence of the medium.

[0065] FIG. 6(B) is a schematic diagram for explaining the situation where the trailing end of the medium passes through the medium sensor before the medium is conveyed by a predetermined amount after the leading end of the medium has passed through the medium sensor.

[0066] As shown in FIG. 6(B), when the trailing end of the medium M3 has passed through the medium sensor 116 before the medium M3 moves by the first distance D1 after the leading end of the medium M3 has passed through the medium sensor 116, it is estimated that the length L2 of the medium M3 is smaller than the first distance D1.

[0067] Before the trailing end of the medium passes through the medium sensor 116 after the leading end of the medium has passed through the medium sensor 116 and before the medium is conveyed by a predetermined amount, when the trailing end of the medium passes through the medium sensor 116, the control unit 151 starts feeding the next medium in the subsequent process. Thereby, the medium conveying device 100 can start feeding the next medium M4 before the small-sized medium M3 is conveyed by a predetermined amount while suppressing the occurrence of double feeding of the medium, and can feed a plurality of small-sized media in a short time.

[0068] If the control unit 151 determines that the trailing end of the medium has not yet passed through the medium sensor 116, the process returns to step S107, and the processes of steps S107 to S108 are repeated.

[0069] On the other hand, when the control unit 151 determines that the trailing end of the medium has passed through the medium sensor 116, it reduces the predetermined amount (step S109) and transfers the process to step S111. The control unit 151 reduces the predetermined amount to an amount that moves the small-sized medium by a third distance (the driving amount of the motor, the rotation amount of the feeding roller 112, or the rotation time of the feeding roller 112).

[0070] The third distance is the distance obtained by subtracting the second distance D2 from the length L2 of the small-sized medium M3 in the medium conveying direction A1. The length L2 is set to the moving (conveying) distance of the medium from when the leading end of the medium passes through the medium sensor 116 until the trailing end of the medium passes through the medium sensor 116. The length L2 may be set to a predetermined length. In that case, the length L2 is set to a size smaller than the size of the medium estimated to be conveyed most frequently in the medium conveying device 100 (for example, the A5 vertical size).

[0071] When the tip of the small-sized medium M3 passes through the medium sensor 116 and then the medium M3 moves by a third distance, the rear end of the medium M3 has passed through the positions of the feed roller 112 and the separation roller 113 (separation unit). It is highly likely that the types of media placed and fed together on the mounting table 103 by the user are the same. If the currently fed medium is a small-sized medium, it is highly likely that the next fed medium is also a small-sized medium. When the currently fed medium is a small-sized medium, the control unit 151 reduces the predetermined amount used for the next fed medium to an amount corresponding to the small size. Thereby, the medium conveyance device 100 can start feeding the next medium before the rear end of the small-sized medium passes through the medium sensor 116 while suppressing the occurrence of double feeding of the medium, and can feed a plurality of small-sized media in a shorter time.

[0072] Note that, for two or more predetermined numbers of continuously fed media, the control unit 151 may reduce the predetermined amount when the rear end of each medium passes through the medium sensor 116 after the tip of each medium passes through the medium sensor 116 and before each medium is conveyed by a predetermined amount. In this case, for a single medium, the control unit 151 does not reduce the predetermined amount even if the rear end of the medium passes through the medium sensor 116 after the tip of the medium passes through the medium sensor 116 and before the medium is conveyed by a predetermined amount. Thereby, the medium conveyance device 100 can be prevented from erroneously reducing the predetermined amount even when the size of the medium is not a small size. Also, thereby, the medium conveyance device 100 can be prevented from erroneously reducing the predetermined amount according to the small-sized medium when media of different sizes are mixed and conveyed on the mounting table 103.

[0073] On the other hand, in step S106, when the size flag is set to the large size, the control unit 151 waits until the rear end of the medium passes through the medium sensor 116 (step S110). The control unit 151 determines whether or not the rear end of the medium has passed through the medium sensor 116 in the same manner as the process of step S108. When the rear end of the medium passes through the medium sensor 116, the control unit 151 shifts the process to step S111.

[0074] FIG. 7 is a schematic diagram for explaining a large-sized medium.

[0075] As shown in FIG. 7, when the size of the medium M5 is large, even if the medium M5 moves a first distance D1 after its leading end passes through the medium sensor 116, the trailing end of the medium M5 may not pass through the feed roller 112 and the separation roller 113 (separation unit). Even when the feeding of the next medium M6 is started in this state, due to the action of the separation roller 113, the medium M6 is separated from the medium M5 and is not fed downstream of the feed roller 112 and the separation roller 113 (separation unit). However, when the frictional force between the separation roller 113 and the medium M6 decreases due to deterioration of the surface of the separation roller 113 or the like, the medium M6 may be fed downstream of the feed roller 112 and the separation roller 113 (separation unit), resulting in double feeding of the medium. When a large-sized medium is fed, the medium conveyance device 100 can more reliably suppress the occurrence of double feeding of the medium by not starting the feeding of the next medium until the trailing end of the medium passes through the medium sensor 116.

[0076] Next, the control unit 151 acquires a placement signal from the placement sensor 111, and determines whether there is a medium remaining on the placement table 103 based on the acquired placement signal (step S111).

[0077] If there is a medium remaining on the placement table 103, the control unit 151 re-drives the motor 131 to re-rotate the feed roller 112 to feed the next medium (step S112). Then, the control unit 151 returns the process to step S106 and repeats the processes after step S106.

[0078] In this way, the control unit 151 starts the feeding of the next medium when the leading end of the medium passes through the medium sensor 116 and the medium is conveyed a predetermined amount. Thereby, the medium conveyance device 100 can feed a plurality of media in a short time while suppressing the occurrence of double feeding of the medium.

[0079] Further, when the rear end of the medium passes through the medium sensor 116 after the leading end of the medium has passed through the medium sensor 116 and before the medium is conveyed by a predetermined amount, the control unit 151 starts feeding the next medium. Thereby, the medium conveying device 100 can feed a plurality of small-sized media in a short time while suppressing the occurrence of double feeding of the media.

[0080] Also, when a large-sized medium is fed, when the rear end of the medium passes through the medium sensor 116, the control unit 151 starts feeding the next medium. Thereby, the medium conveying device 100 can suppress the occurrence of double feeding of the media.

[0081] On the other hand, in step S111, when no medium remains on the mounting table 103, the control unit 151 waits until the rear end of the medium passes through the third conveying roller 118 and the fourth conveying roller 119 (step S113). The control unit 151 determines whether the rear end of the medium has passed through the medium sensor 116 in the same manner as in the process of step S108. When the first hour has elapsed after the rear end of the medium has passed through the medium sensor 116, the control unit 151 determines that the rear end of the medium has passed through the third conveying roller 118 and the fourth conveying roller 119. The first hour is set to the time required for the medium to move the distance between the medium sensor 116 and the third conveying roller 118 and the fourth conveying roller 119.

[0082] Next, the control unit 151 stops the motor 131, stops the separation roller 113, the first conveying roller 114, the second conveying roller 115, the third conveying roller 118 and / or the fourth conveying roller 119 (step S114), and ends a series of steps.

[0083] Note that the processes of steps S108 to S109 may be omitted, and the control unit 151 does not have to start feeding the next medium until the medium is conveyed by a predetermined amount after the leading end of the medium has passed through the medium sensor 116, regardless of whether the rear end of the medium has passed through the medium sensor 116.

[0084] Further, the process of step S109 may be omitted, and even if the rear end of the medium passes the medium sensor 116 after the front end of the medium has passed the medium sensor 116 and before the medium is conveyed by a predetermined amount, the control unit 151 does not have to change the predetermined amount.

[0085] Further, the processes of steps S106 and S110 may be omitted, and the control unit 151 may start feeding the next medium when the medium has been conveyed by a predetermined amount after the front end of the medium has passed the medium sensor 116 even for a large-sized medium. In that case, the control unit 151 may change the predetermined amount according to the length of the medium detected by a known means such as a paper length sensor that detects the paper length arranged on the mounting table 103. Alternatively, the control unit 151 may change the predetermined amount according to the length of the medium set based on an input from a user who designates the paper type using the operation device 105 or the information processing device. Alternatively, the control unit 151 may change the predetermined amount according to the length of the medium detected in step S204 for the medium fed immediately before. Alternatively, the control unit 151 may change the predetermined amount according to a statistical value (average value, median value, maximum value, minimum value, etc.) of the lengths of the media detected in step S204 for two or more predetermined numbers of media fed immediately before.

[0086] Further, in step S207, when the length of the medium detected by the length detection unit 152 for two or more predetermined numbers of continuously fed media is greater than the threshold value, the control unit 151 may set the size flag to the large size.

[0087] FIG. 8 is a flowchart showing an example of the operation of the imaging process of the medium conveyance device.

[0088] Hereinafter, an example of the operation of the imaging process of the medium conveyance device 100 will be described with reference to the flowchart shown in FIG. 8. Note that the operation flow 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. The imaging process is executed in parallel with the medium conveyance process every time a new medium is fed in the medium conveyance process of FIG. 5.

[0089] First, the control unit 151 waits until the leading end of the medium reaches the imaging start position (step S201). The control unit 151 determines, for example, in the same manner as the process of step S104 in FIG. 5, whether the leading end of the medium has passed through the medium sensor 116, and when the leading end of the medium has passed through the medium sensor 116, determines that the leading end of the medium has reached the imaging start position. The control unit 151 may determine that the leading end of the medium has reached the imaging start position when a predetermined time has elapsed since the start of feeding the medium. Alternatively, the control unit 151 may determine that the leading end of the medium has reached the imaging start position when the medium has been conveyed by a predetermined amount after the leading end of the medium has passed through the medium sensor 116.

[0090] Next, the control unit 151 causes the imaging device 117 to start imaging the medium (step S202). Thereafter, each time the imaging device 117 outputs a line image, the control unit 151 acquires the line image output from the imaging device 117 and stores it in the storage device 140.

[0091] Next, the length detection unit 152 waits until the trailing end of the medium passes through the medium sensor 116 (step S203). The length detection unit 152 determines whether the trailing end of the medium has passed through the medium sensor 116 in the same manner as the process of step S108 in FIG. 5.

[0092] Next, the length detection unit 152 detects the length of the medium (step S204). The length detection unit 152 calculates the elapsed time from when it is determined that the leading end of the medium has passed the medium sensor 116 in step S104 of FIG. 5 until the trailing end of the medium passes the medium sensor 116. The length detection unit 152 detects, as the length of the medium, a value obtained by multiplying the calculated elapsed time by the conveyance speed of the medium. The length detection unit 152 may detect the length of the medium based on the drive amount of the motor for driving the feed roller 112 during the calculated elapsed time. In that case, the medium conveyance device 100 stores in advance in the storage device 140 a relational expression between the drive amount of the motor and the moving distance of the medium, and the length detection unit 152 refers to the relational expression and calculates, as the length of the medium, the moving distance of the medium corresponding to the drive amount of the motor.

[0093] Next, the control unit 151 determines whether the length of the medium detected by the length detection unit 152 is greater than a threshold value (step S205). The threshold value is set, for example, to a size obtained by adding the distance from the specific position P2 to the feed roller 112 and the separation roller 113 (separation unit) to the above-described specific size (for example, A4 portrait size).

[0094] If the length of the medium detected by the length detection unit 152 is equal to or less than the threshold value, the control unit 151 sets the size flag to a non-large size (step S206). In this case, in the medium conveyance process of FIG. 5, when the next medium is fed, it is determined in step S106 that the size flag is set to a non-large size, and the processes of steps S107 to S109 are executed.

[0095] On the other hand, when the length of the medium detected by the length detection unit 152 is greater than the threshold value, the control unit 151 sets the size flag to the large size (step S207). In this case, in the medium conveyance process of FIG. 5, when the next medium is fed, it is determined in step S106 that the size flag is set to the large size, and the process of step S110 is executed. That is, when the length of the medium detected by the length detection unit 152 is greater than the threshold value, the control unit 151 starts feeding the next medium when the trailing end of the next medium passes the medium sensor 116. Thereby, the control unit 151 can suppress starting the feeding of the next medium before the trailing end of the medium passes through the feeding roller 112 and the separation roller 113 (separation unit), and can suppress the occurrence of double feeding of the medium.

[0096] Next, the control unit 151 waits until the trailing end of the medium passes the imaging position of the imaging device 117 (step S208). The control unit 151 determines whether or not the trailing end of the medium has passed the medium sensor 116 in the same manner as the process of step S108 in FIG. 5. The control unit 151 determines that the trailing end of the medium has passed the imaging position of the imaging device 117 when the second time has elapsed since the trailing end of the medium passed the medium sensor 116. The second time is set to the time required for the medium to move the distance between the medium sensor 116 and the imaging position of the imaging device 117.

[0097] Next, the control unit 151 ends the imaging by the imaging device 117 (step S209).

[0098] Next, the control unit 151 combines the line images output from the imaging device 117 and stored in the storage device 140 to generate an input image. The control unit 151 outputs the generated input image by transmitting it to the information processing device via the interface device 132 (step S210), and ends a series of steps.

[0099] Note that, instead of the medium sensor 116, the imaging device 117 may be used as the detection unit, and the control unit 151 may determine the start timing of the feeding of the medium based on the line image instead of the medium signal. In that case, in the medium conveyance device 100, the medium sensor 116 may be omitted.

[0100] In this case, in step S201 of FIG. 8, the control unit 151 determines that the leading end of the medium has reached the imaging start position when the third hour has elapsed since the start of the feeding of the medium. The third hour is set to the time required for the leading end of the medium to pass through the nip portion of the feeding roller 112 and the separation roller 113 (separation unit). The third hour may be set to 0, and the control unit 151 may determine that the leading end of the medium has reached the imaging start position when the feeding of the medium is started.

[0101] Also, in step S104 of FIG. 5, the control unit 151 waits until the leading end of the medium passes through the imaging position of the imaging device 117. The control unit 151 sequentially acquires line images from the medium sensor 116 and detects the leading end of the medium using known image processing techniques. For example, the control unit 151 extracts edge pixels in each line image whose difference in gradation value (luminance value, color value, etc.) from adjacent pixels is equal to or greater than a predetermined gradation threshold. The control unit 151 determines that the leading end of the medium has passed through the imaging device 117 when edge pixels are first extracted in any of the sequentially acquired line images. Also, in step S107 of FIG. 5, the second distance is set to the distance from the imaging position of the imaging device 117 to the specific position P2.

[0102] Also, in step S108 of FIG. 5, the control unit 151 determines whether or not the rear end of the medium has passed through the imaging device 117 (imaging position). The control unit 151 sequentially acquires line images from the imaging device 117 and detects the rear end of the medium using known image processing techniques. For example, the control unit 151 extracts edge pixels within each line image in the same manner as the process of step S104. The control unit 151 determines that the rear end of the medium has passed through the imaging device 117 when edge pixels are extracted in any line image and no edge pixels are extracted in the line images acquired thereafter. Similarly, in step S110 of FIG. 5, the control unit 151 determines whether or not the rear end of the medium has passed through the imaging device 117 and waits until the rear end of the medium passes through the imaging device 117.

[0103] Also, in step S113 of FIG. 5, the control unit 151 determines that the rear end of the medium has passed through the third transport roller 118 and the fourth transport roller 119 when the fourth hour has elapsed since the rear end of the medium passed through the imaging device 117. The fourth hour is set to the time required for the medium to move the distance between the imaging device 117 (imaging position) and the third transport roller 118 and the fourth transport roller 119.

[0104] Also, in step S203 of FIG. 8, the length detection unit 152 determines whether or not the rear end of the medium has passed through the imaging device 117 and waits until the rear end of the medium passes through the imaging device 117. In step S204, the length detection unit 152 detects, as the length of the medium, a value obtained by multiplying the elapsed time from when the front end of the medium passes through the imaging device 117 until the rear end of the medium passes through the imaging device 117 by the transport speed of the medium. The length detection unit 152 may detect the length of the medium based on the drive amount of the motor for driving the feed roller 112 during that elapsed time. Further, the length detection unit 152 may detect the front end and the rear end of the medium from each line image using known image processing techniques and detect the length of the medium based on the number of lines and the resolution between the line images in which the front end and the rear end of the medium are detected. Also, in step S203, since waiting until the rear end of the medium passes through the imaging device 117, the process of step S208 is omitted.

[0105] Also, the number of media sensors 116 is not limited to one, and a plurality may be used. For example, the media conveyance device 100 may have a plurality of media sensors 116 arranged at intervals in the width direction A2, and each media sensor 116 may be used to detect the skew of the media. In that case, the control unit 151 determines whether the leading edge of the media has passed each media sensor 116 based on the media signals acquired from each media sensor 116, and stores the time when the leading edge of the media has passed each media sensor 116 in the storage device 140. The control unit 151 calculates the inclination of the media based on the difference in the times when the leading edge of the media has passed each media sensor 116, the conveyance speed of the media, and the distance between each media sensor 116. When the calculated inclination of the media is greater than a preset inclination threshold value, the control unit 151 determines that skew of the media has occurred.

[0106] Also, the control unit 151 may change the timing at which the feeding of the next media is started according to the inclination of the media. For example, the control unit 151 makes the timing at which the feeding of the next media is started when skew of the media has occurred later than the timing at which the feeding of the next media is started when no skew of the media has occurred. Thereby, the media conveyance device 100 can suppress the occurrence of media jams in which the leading edge of the newly fed media collides with the trailing edge of the previously fed media in an inclined state. Further, the control unit 151 may make the timing at which the feeding of the next media is started later as the inclination of the media is greater. Thereby, the media conveyance device 100 can more effectively suppress the occurrence of media jams in which the leading edge of the newly fed media collides with the trailing edge of the previously fed media in an inclined state.

[0107] Also, a predetermined amount for comparing with the conveyance amount of the fed medium and / or a threshold value for comparing with the length of the fed medium may be set by the user. In that case, in step S101 of FIG. 5, the reception unit 153 receives the setting of the predetermined amount and / or the threshold value by the user. The reception unit 153 receives, for example, a profile set by the user using the information processing apparatus together with an operation signal for instructing the reading of the medium, before an instruction for reading the medium is input by the user. The profile is setting information for defining the operations for the medium conveyance device 100 to convey and / or image the medium. The profile includes a predetermined amount and / or a threshold value in addition to the feeding mode, the resolution of the image, the color, etc. The reception unit 153 may receive the predetermined amount and / or the threshold value specified by the user using the operation device 105 from the operation device 105. Thereby, the medium conveyance device 100 can set, for each user, parameters for determining the start timing of the feeding of the medium according to the type of the medium to be read, the use of the image obtained by imaging the medium, etc.

[0108] Also, instead of the predetermined amount, the reception unit 153 may receive a setting such as the medium size (standard sizes such as A5 portrait size, A4 portrait size, etc.) or the medium length. In that case, the reception unit 153 calculates the first distance D1 based on the set medium size or medium length, and calculates a predetermined amount from the calculated first distance D1.

[0109] As described in detail above, when the leading end of the medium passes through the medium sensor 116 disposed downstream of the first conveyance roller 114 and the second conveyance roller 115 and then the medium is conveyed by a predetermined amount, the medium conveyance device 100 starts the feeding of the next medium. Thereby, the medium conveyance device 100 can start the feeding of the next medium at an appropriate timing while suppressing the occurrence of double feeding of the medium, and can feed the medium at a more appropriate timing.

[0110] In particular, the media conveyance device 100 determines the timing to start feeding the media by using the media sensor 116 or the imaging device 117 itself, which is used to specify the imaging timing by the imaging device 117. Thereby, the media conveyance device 100 can appropriately determine the timing to start feeding the media without using a dedicated sensor for determining the timing to start feeding the media. Therefore, the media conveyance device 100 can improve the processing performance of the media conveyance process while suppressing an increase in device cost and power consumption.

[0111] Also, the media conveyance device 100 can improve the processing performance of the media conveyance process by shortening the interval between the fed media without increasing (speeding up) the conveyance speed of the media. Therefore, the media conveyance device 100 can improve the processing performance of the media conveyance process while suppressing an increase in power consumption by the motor 131.

[0112] FIG. 9 is a diagram for explaining a conveyance path inside a media conveyance device according to another embodiment.

[0113] The media conveyance device 200 shown in FIG. 9 has the same configuration and functions as the media conveyance device 100. However, the media conveyance device 200 further has a second media sensor 220 in addition to each part that the media conveyance device 100 has.

[0114] The second media sensor 220 is an example of a second detection unit, and detects the media conveyed to its arrangement position. The second media sensor 220 is arranged between the feed roller 112 and the separation roller 113 (separation unit) and the first conveyance roller 114 and the second conveyance roller 115 in the media conveyance direction A1.

[0115] The second medium sensor 220 includes a light emitter and a light receiver provided on one side with respect to the medium conveyance path, and a light guide pipe provided at a position facing the light emitter and the light receiver with the medium conveyance path interposed therebetween. 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 detects (receives) the light irradiated by the light emitter and guided by the light guide pipe. When a medium exists at a position facing at least one of the light emitter and the light receiver, 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 220 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 220 based on the intensity of the light received by the light receiver.

[0116] Thus, the second medium sensor 220 is a light detection sensor that irradiates light toward the medium conveyance path and detects the received light. Note that in the second medium sensor 220, a reflection member such as a mirror may be used instead of the light guide pipe. Also, in the second medium sensor 220, the light emitter and the light receiver may be provided to face each other with the medium conveyance path interposed therebetween. Further, the second medium sensor 220 may detect the presence of a medium by an ultrasonic sensor, a contact detection sensor, an encoder, or the like.

[0117] When the medium conveyance process of FIG. 5 is executed by the medium conveyance device 200, in step S108, the control unit 151 determines whether or not the rear end of the medium has passed the second medium sensor 220. The control unit 151 periodically acquires the second medium signal from the second medium sensor 220, and determines that the rear end of the medium has passed the second medium sensor 220 when the signal value of the second medium signal changes from a value indicating the presence of a medium to a value indicating the absence of a medium.

[0118] FIG. 10 is a schematic diagram for explaining the situation where the rear end of a medium passes the second medium sensor before the medium is conveyed by a predetermined amount after the front end of the medium passes the medium sensor.

[0119] As shown in FIG. 10, in the medium conveyance direction A1, the second medium sensor 220 is disposed downstream of the feed roller 112 and the separation roller 113 (separation unit) and upstream of the medium sensor 116. Therefore, when the rear end of the small-sized medium M3 passes through the second medium sensor 220, the rear end of the medium M3 has already passed through the feed roller 112 and the separation roller 113 (separation unit). Also, the rear end of the small-sized medium M3 passes through the second medium sensor 220 before passing through the medium sensor 116.

[0120] When the rear end of the medium passes through the second medium sensor 220 before the medium is conveyed by a predetermined amount after the front end of the medium passes through the medium sensor 116, the control unit 151 starts feeding the next medium in step S112. Thereby, the medium conveyance device 200 can start feeding the next medium M4 before the rear end of the small-sized medium M3 passes through the medium sensor 116 while suppressing the occurrence of double feeding of the medium, and can feed a plurality of small-sized media in a shorter time.

[0121] Also, when the medium conveyance process of FIG. 5 is executed by the medium conveyance device 200, in step S110, the control unit 151 waits until the rear end of the medium passes through the second medium sensor 220. The control unit 151 determines whether or not the rear end of the medium has passed through the second medium sensor 220 in the same manner as the process of step S108.

[0122] That is, when the length of the medium detected by the length detection unit 152 is greater than the threshold value, the control unit 151 starts feeding the next next medium when the rear end of the next medium passes through the second medium sensor 220. When a large-sized medium is fed, the medium conveyance device 200 can more reliably suppress the occurrence of double feeding of the medium by not starting to feed the next medium until the rear end of the medium passes through the second medium sensor 220. Further, the medium conveyance device 200 can start feeding the next medium M4 before the rear end of the large-sized medium passes through the medium sensor 116, and can feed a plurality of large-sized media in a shorter time.

[0123] Also, when the imaging process of FIG. 8 is executed by the medium conveyance device 200, in step S204, the length detection unit 152 may detect the length of the medium based on the second medium signal from the second medium sensor 220. In that case, in step S203, the length detection unit 152 waits until the rear end of the medium passes the second medium sensor 220. The length detection unit 152 periodically acquires the second medium signal from the second medium sensor 220, and 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, it determines that the front end of the medium has passed the second medium sensor 220. The length detection unit 152 calculates the elapsed time from when the front end of the medium passes the second medium sensor 220 until the rear end of the medium passes the second medium sensor 220. The length detection unit 152 detects, as the length of the medium, a value obtained by multiplying the calculated elapsed time by the conveyance speed of the medium. The length detection unit 152 may also detect the length of the medium based on the drive amount of the motor for driving the feed roller 112 during the calculated elapsed time.

[0124] As described in detail above, even when the medium conveyance device 200 uses the second medium sensor 220, it is possible to suppress the occurrence of double feeding of the medium and start feeding the next medium at an appropriate timing, and it has become possible to feed the medium at a more appropriate timing.

[0125] FIG. 11 is a diagram for explaining the conveyance path inside the medium conveyance device according to still another embodiment.

[0126] The medium conveyance device 300 shown in FIG. 11 has the same configuration and functions as the medium conveyance device 100. However, the medium conveyance device 300 has an imaging device 317 instead of the imaging device 117 that the medium conveyance device 100 has. Also, the medium sensor 116 may be omitted in the medium conveyance device 300.

[0127] The imaging device 317 is an example of a detection unit and a second detection unit. The imaging device 317 includes a first imaging device 317a and a second imaging device 317b, and images a medium. The first imaging device 317a and the second imaging device 317b each have the same configuration and function as the first imaging device 117a and the second imaging device 117b. However, the first imaging device 317a and the second imaging device 317b are arranged at mutually different positions in the medium conveyance direction A1, that is, so as not to face each other. The first imaging device 317a is arranged upstream of the first conveyance roller 114 and the second conveyance roller 115, and the second imaging device 317b is arranged downstream of the first conveyance roller 114 and the second conveyance roller 115. Note that the first imaging device 317a may be arranged downstream of the first conveyance roller 114 and the second conveyance roller 115, and the second imaging device 317b may be arranged upstream of the first conveyance roller 114 and the second conveyance roller 115. Also, the first imaging device 317a and the second imaging device 317b may be arranged at mutually different positions downstream of the first conveyance roller 114 and the second conveyance roller 115 in the medium conveyance direction A1.

[0128] When the medium conveyance process of FIG. 5 and the imaging process of FIG. 8 are executed by the medium conveyance device 300, in step S201 of FIG. 8, the control unit 151 determines that the leading end of the medium has reached the imaging start position when the third hour has elapsed since the start of feeding the medium.

[0129] Also, in step S104 of FIG. 5, the control unit 151 waits until the leading end of the medium passes through the imaging position of the imaging device arranged downstream among the first imaging device 317a and the second imaging device 317b. The control unit 151 sequentially acquires line images from the imaging device, and detects the leading end of the medium using a known image processing technique. Also, in step S107 of FIG. 5, the second distance is set to the distance from the imaging position of the imaging device arranged downstream to the specific position P2.

[0130] Also, in step S108 of FIG. 5, the control unit 151 determines whether or not the rear end of the medium has passed through the imaging position of the imaging device arranged on the upstream side among the first imaging device 317a and the second imaging device 317b. The control unit 151 sequentially acquires line images from the imaging device and detects the rear end of the medium using known image processing techniques. Similarly, in step S110 of FIG. 5, the control unit 151 determines whether or not the rear end of the medium has passed through the imaging device arranged on the upstream side, and waits until the rear end of the medium passes through the imaging device.

[0131] Also, in step S113 of FIG. 5, when the fifth time has elapsed after the rear end of the medium has passed through any one of the first imaging device 317a and the second imaging device 317b, the control unit 151 determines that the rear end of the medium has passed through the third conveying roller 118 and the fourth conveying roller 119. The fifth time is set to the time required for the medium to move the distance between the imaging position of the imaging device and the third conveying roller 118 and the fourth conveying roller 119.

[0132] Also, in step S203 of FIG. 8, the length detection unit 152 determines whether or not the rear end of the medium has passed through any one of the first imaging device 317a and the second imaging device 317b, and waits until the rear end of the medium passes through the imaging device. In step S204, the length detection unit 152 calculates the elapsed time from when the front end of the medium passes through the imaging device until the rear end of the medium passes through the imaging device. The length detection unit 152 detects, as the length of the medium, a value obtained by multiplying the calculated elapsed time by the conveyance speed of the medium. The length detection unit 152 may detect the length of the medium based on the driving amount of the motor for driving the feeding roller 112 during the calculated elapsed time.

[0133] Also, in step S208, the control unit 151 determines whether or not the rear end of the medium has passed through the imaging device arranged on the downstream side among the first imaging device 317a and the second imaging device 317b, and waits until the rear end of the medium passes through the imaging device.

[0134] Note that the medium sensor 116 may be used as the detection unit, and the imaging device 317 may be used as the second detection unit. In that case, in step S104 of FIG. 5, the control unit 151 waits until the leading end of the medium passes through the medium sensor 116. In step S108, the control unit 151 determines whether or not the trailing end of the medium has passed through the imaging position of the imaging device arranged on the upstream side among the first imaging device 317a and the second imaging device 317b. Further, the medium conveyance device 300 may include the second medium sensor 220 described above, the imaging device 317 may be used as the detection unit, and the second medium sensor 220 may be used as the second detection unit. In that case, in step S104 of FIG. 5, the control unit 151 waits until the leading end of the medium passes through the imaging position of the imaging device arranged on the downstream side among the first imaging device 317a and the second imaging device 317b. In step S108, the control unit 151 determines whether or not the trailing end of the medium has passed through the second medium sensor 220. In these cases, one of the first imaging device 317a and the second imaging device 317b may be omitted.

[0135] As described in detail above, when using the imaging device 317, the medium conveyance device 300 can start feeding the next medium at an appropriate timing while suppressing the occurrence of double feeding of the medium, and can feed the medium at a more appropriate timing.

[0136] In particular, similar to the media transport device 200, the media transport device 300 can start feeding the next media before the rear end of a small-sized media passes through an imaging device with the rear end of the small-sized media arranged on the downstream side, and can feed a plurality of small-sized media in a shorter time. Also, similar to the media transport device 200, the media transport device 300 can start feeding the next media before the rear end of a large-sized media passes through an imaging device with the rear end of the large-sized media arranged on the downstream side, and can feed a plurality of large-sized media in a shorter time. Further, similar to the media transport device 100, the media transport device 300 can appropriately determine the timing to start feeding the media without using a special sensor for determining the timing to start feeding the media. Therefore, the media transport device 300 can improve the processing performance of the media transport process while suppressing an increase in device cost and power consumption.

[0137] FIG. 12 is a diagram for explaining a transport path inside a media transport device according to still another embodiment.

[0138] The media transport device 400 shown in FIG. 12 has the same configuration and functions as the media transport device 100. However, the media transport device 400 has an imaging device 417 instead of the imaging device 117 that the media transport device 100 has. The imaging device 417 includes a first imaging device 417a and a second imaging device 417b. The configurations and functions of the first imaging device 417a and the second imaging device 417b are the same as those of the first imaging device 117a and the second imaging device 117b. However, the first imaging device 417a and the second imaging device 417b are arranged at different positions in the media transport direction A1, that is, not facing each other. In the media transport direction A1, a transport roller pair different from the first transport roller 114, the second transport roller 115, the third transport roller 118, and the fourth transport roller 119 may be arranged between the first imaging device 417a and the second imaging device 417b.

[0139] As described in detail above, even when using the imaging device 417, the media transport device 400 can start feeding the next media at an appropriate timing while suppressing the occurrence of media refeeding, and can feed the media at a more appropriate timing.

[0140] FIG. 13 is a diagram showing a schematic configuration of a processing circuit in a media transport device according to still another embodiment.

[0141] The processing circuit 550 is used instead of the processing circuit 150 of the media transport device 100, and executes media transport processing, imaging processing, etc. instead of the processing circuit 150. The processing circuit 550 includes a control circuit 551, a length detection circuit 552, a reception circuit 553, etc. Note that each of these units may be configured by an independent integrated circuit, microprocessor, firmware, etc.

[0142] The control circuit 551 is an example of a control unit and has the same functions as the control unit 151. The control circuit 551 receives an operation signal from the operation device 105 or the interface device 132, a placement signal from the placement sensor 111, a media signal from the media sensor 116, and a second media signal from the second media sensor 220. Also, the control circuit 551 receives the length of the media from the length detection circuit 552, and a predetermined amount and a threshold value from the reception circuit 553. The control circuit 551 controls the motor 131 based on each received piece of information, acquires a line image from the imaging devices 117, 317, or 417 to generate an input image, and outputs it to the interface device 132.

[0143] The length detection circuit 552 is an example of a length detection unit and has the same functions as the length detection unit 152. The length detection circuit 552 receives a media signal from the media sensor 116 and a second media signal from the second media sensor 220. The length detection circuit 552 detects the length of the media based on each received signal and outputs it to the control circuit 551.

[0144] The reception circuit 553 is an example of a reception unit and has the same functions as the reception unit 153. The reception circuit 553 receives a predetermined amount and a threshold value set by the user from the operation device 105 or the interface device 132 and outputs them to the control circuit 551.

[0145] As described in detail above, even when the processing circuit 550 is used, the medium conveyance device can start feeding the next medium at an appropriate timing while suppressing the occurrence of double feeding of the medium, and can feed the medium at a more appropriate timing.

[0146] As described above, the preferred embodiments have been explained, but the embodiments are not limited to these. For example, the medium conveyance device may have a so-called U-turn path, feed and convey the media placed on the mounting table in order from above, and discharge them to the discharge table. In that case, the feed roller is disposed above the separation roller and opposed to the separation roller. Also in this case, the medium conveyance device can start feeding the next medium at an appropriate timing while suppressing the occurrence of double feeding of the medium, and can feed the medium at a more appropriate timing.

Explanation of Reference Numerals

[0147] 100 Medium conveyance device, 112 Feed roller, 113 Separation roller, 114 First conveyance roller, 115 Second conveyance roller, 116 Medium sensor, 117 Imaging device, 118 Third conveyance roller, 119 Fourth conveyance roller, 151 Control unit, 152 Length detection unit, 153 Reception unit, 220 Second medium sensor

Claims

1. A feeding roller for feeding a medium, A pair of conveying rollers arranged downstream of the feeding roller in the medium conveying direction, A detection unit arranged downstream of the pair of conveying rollers in the medium conveying direction, A control unit that starts feeding the next medium when the leading end of the medium passes through the detection unit and then the medium is conveyed by a predetermined amount, A medium conveying device, characterized by comprising the above components.

2. The control unit starts feeding the next medium when the trailing end of the medium passes through the detection unit before the medium is conveyed by the predetermined amount after the leading end of the medium passes through the detection unit. The medium conveying device according to Claim 1.

3. Further comprising a second detection unit arranged between the feeding roller and the pair of conveying rollers, The control unit starts feeding the next medium when the trailing end of the medium passes through the second detection unit before the medium is conveyed by the predetermined amount after the leading end of the medium passes through the detection unit. The medium conveying device according to Claim 1.

4. Further comprising a length detection unit for detecting the length of the medium, When the detected length of the medium is greater than a threshold value, the control unit starts feeding the next medium when the trailing end of the next medium passes through the detection unit. The medium conveying device according to Claim 1.

5. A second detection unit arranged between the feeding roller and the pair of conveying rollers for detecting the medium, And a length detection unit for detecting the length of the medium, When the detected length of the medium is greater than a threshold value, the control unit starts feeding the next medium when the trailing end of the next medium passes through the second detection unit. The medium conveying device according to Claim 1.

6. The detection unit is a light detection sensor that irradiates light toward the medium conveying path and detects the received light. The medium conveying device according to Claim 1 or 2.

7. The detection unit is an imaging device for imaging the medium. The medium conveying device according to Claim 1 or 2.

8. Further comprising a reception unit for receiving the setting of the predetermined amount by the user. The medium conveying device according to Claim 1 or 2.

9. Further comprising a reception unit for receiving the setting of the threshold value by the user. The medium conveying device according to Claim 4 or 5.

10. Feed the medium by a feeding roller, When the leading end of the medium passes through a detection unit arranged downstream of a pair of conveying rollers arranged downstream of the feeding roller in the medium conveying direction and then the medium is conveyed by a predetermined amount, start feeding the next medium. A medium conveyance method characterized by the following.

11. A control program for a medium conveyance device, comprising: a feed roller that feeds a medium; a pair of conveyance rollers disposed downstream of the feed roller in the medium conveyance direction; and a detection unit disposed downstream of the pair of conveyance rollers in the medium conveyance direction, wherein when the leading end of the medium passes through the detection unit and the medium is conveyed by a predetermined amount, feeding of the next medium is started. A control program characterized by causing the medium conveyance device to execute the above.

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