Medium feeding device, medium feeding method and control program

Abstract

To provide a medium feeding device, a medium feeding method and a control program which can feed a medium more properly.SOLUTION: A medium feeding device comprises: a first sensor arranged closer to an upstream side than a feeding roller and a separating roller, in a medium conveying direction; a second sensor arranged closer to a downstream side than the feeding roller and the separating roller, in the medium conveying direction; a third sensor that detects rotation of the separating roller; and a control part that controls a motor so that the separating roller is held until the second sensor detects a tip of the medium after feeding of the medium is started, controls the motor so that the motor generates driving force until the first sensor detects a rear end of the medium after the second sensor detects the tip of the medium, and controls the motor so that the motor generates driving force, while stopping the feeding roller, when the third sensor detects rotation in the opposite direction of the medium feeding direction of the separating roller during feeding of the medium.SELECTED DRAWING: Figure 7

Description

[Technical field]

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

[0002] A medium feeding device such as a scanner feeds and captures a plurality of media while separating the media one by one. When a duplicated medium feed occurs in such a medium feeding device, the user must remove the media from the housing and reset the media on the placement table. In the medium feeding device, it is desirable to reduce the possibility of duplicated media feed occurring in order to improve user convenience.

[0003] A paper feeding device is disclosed that detects the rotational speed of a retard roller, and controls the paper feeding means to continue feeding the recording material if the rotational speed is equal to or greater than a first value, and to stop the paper feeding operation if the rotational speed is less than the first value (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-105602 A Summary of the Invention [Problem to be solved by the invention]

[0005] There is a demand for a media feeding device that can more appropriately feed media.

[0006] An object of the present invention is to provide a medium feeding device, a medium feeding method, and a control program that are capable of more appropriately feeding a medium. [Means for solving the problem]

[0007] A medium feeding device according to one aspect of the present invention has a feed roller for feeding a medium, a separation roller arranged opposite the feed roller, a motor for generating a driving force to rotate the separation roller in a direction opposite to the medium feeding direction, a first sensor arranged upstream of the feed roller and the separation roller in the medium transport direction, a second sensor arranged downstream of the feed roller and the separation roller in the medium transport direction, a third sensor for detecting rotation of the separation roller, and a control unit for feeding the medium by rotating the feed roller in the medium feeding direction, wherein the control unit controls the motor to hold the separation roller from when medium feeding begins until the second sensor detects the leading edge of the medium, and controls the motor to generate a driving force from when the second sensor detects the leading edge of the medium until the first sensor detects the trailing end of the medium, and when the third sensor detects rotation of the separation roller in the direction opposite to the medium feeding direction during medium feeding, controls the motor to stop the feed roller and generate a driving force.

[0008] A medium feeding method according to one aspect of the present invention feeds a medium by rotating a feed roller in a medium feeding direction, controls a motor to hold the separation roller from when medium feeding begins until a second sensor located downstream of the feed roller and a separation roller located opposite the feed roller in the media transport direction detects the leading edge of the medium, and controls the motor to generate a driving force to rotate the separation roller in the opposite direction to the medium feeding direction from when the second sensor detects the leading edge of the medium until a first sensor located upstream of the feed roller and separation roller in the media transport direction detects the rear end of the medium, and controls the motor to generate a driving force while stopping the feed roller when a third sensor detects rotation of the separation roller in the opposite direction to the media feeding direction during medium feeding.

[0009] A control program according to one aspect of the present invention is a control program for a medium feeding device having a feed roller that feeds a medium, a separation roller arranged opposite the feed roller, a motor that generates a driving force to rotate the separation roller in a direction opposite to the medium feeding direction, a first sensor arranged upstream of the feed roller and the separation roller in the medium transport direction, a second sensor arranged downstream of the feed roller and the separation roller in the medium transport direction, and a third sensor that detects rotation of the separation roller, and causes the medium feeding device to feed the medium by rotating the feed roller in the medium feeding direction, control the motor to hold the separation roller from when medium feeding begins until the second sensor detects the leading edge of the medium, and control the motor to generate a driving force from when the second sensor detects the leading edge of the medium until the first sensor detects the trailing end of the medium, and if the third sensor detects rotation of the separation roller in the direction opposite to the medium feeding direction during medium feeding, control the motor to generate a driving force while stopping the feed roller. Effect of the Invention

[0010] According to the present invention, the medium feeding device, the medium feeding method, and the control program are capable of feeding the medium more appropriately. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view showing a medium feeding device 100. [Diagram 2] 2 is a diagram for explaining a transport path inside the medium feeding device 100. FIG. [Diagram 3] 1A and 1B are schematic diagrams for explaining a first arm 131 and a second arm 132. FIG. [Figure 4] 2 is a schematic diagram for explaining a pick roller 113. FIG. [Diagram 5] 1 is a block diagram showing a schematic configuration of a medium feeding device 100. FIG. [Figure 6] FIG. 2 is a diagram showing a schematic configuration of a storage device 150 and a processing circuit 160. [Figure 7]10 is a flowchart illustrating an example of the operation of a medium reading process. [Figure 8] 10 is a flowchart illustrating an example of the operation of a medium reading process. [Figure 9] 1A to 1C are schematic diagrams illustrating the feeding of a medium. [Figure 10] 1A to 1C are schematic diagrams illustrating the feeding of a medium. [Figure 11] 13 is a flowchart illustrating an example of an operation of a skew determination process. [Figure 12] 13 is a flowchart showing an example of an operation of a pasting determination process. [Figure 13] FIG. 13 is a diagram showing a schematic configuration of a processing circuit 260 according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, a medium feeding device, a medium feeding method, and a control program according to one aspect of the present invention 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 the embodiments, but extends to the inventions described in the claims and their equivalents.

[0013] 1 is a perspective view showing a medium feeding device 100 configured as an image scanner. The medium feeding device 100 conveys a medium, which is an original, and captures an image. The medium is paper, cardboard, card, or the like. The medium feeding device 100 may be a facsimile, a copier, a printer multifunction peripheral (MFP), or the like.

[0014] 1, arrow A1 indicates the substantially vertical direction (height direction), arrow A2 indicates the medium transport direction, arrow A3 indicates the medium discharge direction, and arrow A4 indicates the width direction perpendicular to the medium transport direction A2 or the medium discharge direction A3. In the following, upstream refers to the upstream of the medium transport direction A2 or the medium discharge direction A3, and downstream refers to the downstream of the medium transport direction A2 or the medium discharge direction A3.

[0015] The medium feeding device 100 includes a first housing 101, a second housing 102, a placement table 103, a discharge table 104, an operation device 105, a display device 106, and the like.

[0016] The second housing 102 is disposed inside the first housing 101 and rotatably engaged with the first housing 101 by a hinge so that the second housing 102 can be opened and closed when a medium is jammed or when the inside of the medium feeding device 100 is cleaned.

[0017] The placement table 103 engages with the first housing 101 so that the medium to be transported can be placed thereon. The placement table 103 is provided on the side surface of the first housing 101 on the medium supply side so as to be movable in the height direction A1. The placement table 103 is disposed at the bottom end position so that the medium can be easily placed thereon when the medium is not being transported, and when the medium is being transported, the uppermost medium placed on the placement table 103 rises to a position where it comes into contact with a pick roller, which will be described later.

[0018] The discharge stage 104 is formed on the second housing 102. The discharge stage 104 places the media discharged from the discharge ports of the first housing 101 and the second housing 102 thereon.

[0019] The operation device 105 has an input device such as a button and an interface circuit for acquiring a signal from the input device, accepts an input operation by a user, and outputs an operation signal according to the user's input operation. The display device 106 has a display including a liquid crystal, an organic EL (Electro-Luminescence), or the like, and an interface circuit for outputting image data to the display, and displays the image data on the display. The display device 106 may be a liquid crystal display with a touch panel function. In that case, the operation device 105 has an interface circuit for acquiring an input signal from the touch panel.

[0020] FIG. 2 is a diagram for explaining the transport path inside the medium feeding device 100. As shown in FIG.

[0021] The transport path inside the medium feeding device 100 has a first media sensor 111, a first encoder 112, a pick roller 113, a feed roller 114, a separation roller 115, a second encoder 116, a second media sensor 117, a third media sensor 118, a first skew sensor 119, a second skew sensor 120, an ultrasonic sensor 121, first to sixth transport rollers 122a-f, first to sixth driven rollers 123a-f, a fourth media sensor 124, and an imaging device 125, etc.

[0022] The number of each of the pick roller 113, the feed roller 114, the separation roller 115, the first to sixth conveyor rollers 122a-f, and / or the first to sixth driven rollers 123a-f is not limited to one, and may be more than one. In this case, the multiple feed rollers 114, the separation roller 115, the first to sixth conveyor rollers 122a-f, and / or the first to sixth driven rollers 123a-f are arranged at intervals in the width direction A4.

[0023] The second housing 102 is disposed opposite the first housing 101 across the medium transport path. The surface of the first housing 101 facing the second housing 102 forms a first guide 101a of the medium transport path, and the surface of the second housing 102 facing the first housing 101 forms a second guide 102a of the medium transport path.

[0024] The first medium sensor 111 is disposed on the mounting table 103, that is, upstream of the feed roller 114 and the separation roller 115, and detects the state of the medium on the mounting table 103. The first medium sensor 111 determines whether or not a medium is placed on the mounting table 103 by using a contact detection sensor that passes a predetermined current when the medium is in contact or not in contact. The first medium sensor 111 generates and outputs a first medium signal whose signal value changes depending on whether the medium is placed on the mounting table 103 or not. Note that the first medium sensor 111 is not limited to a contact detection sensor, and any other sensor capable of detecting the presence or absence of a medium, such as a light detection sensor, may be used as the first medium sensor 111.

[0025] The first encoder 112 is an example of a first sensor. The first encoder 112 is disposed in the second housing 102 upstream of the feed roller 114 and the separation roller 115 in the medium conveying direction A2, and detects the movement of the medium in contact with the first encoder 112 to detect the rear end of the medium being fed. In particular, the first encoder 112 is disposed upstream of the pick roller 113 in the medium conveying direction A2, particularly in the vicinity of the pick roller 113. The first encoder 112 has a disk in which a large number of slits (light transmission holes) are formed and which is provided to rotate according to the medium being fed, and a light emitter and a light receiver which are provided to face each other across the disk. The light emitter is an LED (Light Emitting Diode) or the like, and emits light toward the disk (light receiver). The light receiver is a photodiode or the like, and receives the light emitted by the light emitter via the disk. The light receiver detects the number of times that the state changes from a state in which there is a slit between the light emitter and the light receiver to a state in which there is no slit and the light is blocked by the disk within a predetermined period. The light receiver detects the movement distance of the medium being fed by multiplying the detected number of changes by the distance that the outer circumferential surface of the first encoder 112 moves when the disk rotates by the distance between two adjacent slits. The first encoder 112 generates and outputs a distance signal indicating the detected movement distance. When the rear end of the medium being fed passes the position of the first encoder 112, the movement distance of the medium changes from a value greater than 0 to 0, so that the first encoder 112 can detect the rear end of the medium from the movement distance of the medium. Note that the first encoder 112 is not limited to an optical encoder, and may be any encoder such as a mechanical encoder, a magnetic encoder, or an electromagnetic induction encoder.

[0026] Pick roller 113 is disposed in second housing 102, upstream of feed roller 114 and separation roller 115 in media transport direction A2. Pick roller 113 comes into contact with the uppermost medium among the media placed on mounting table 103, which has been raised to approximately the same height as the media transport path, and transports the medium downstream. A one-way clutch is provided between pick roller 113 and a motor that imparts a driving force to pick roller 113, so as to restrict rotation of pick roller 113 in the opposite direction to media feed direction A11.

[0027] The feed roller 114 is provided in the second housing 102 downstream of the pick roller 113, and feeds the medium placed on the placement table 103 and fed by the pick roller 113 further downstream. When a plurality of feed rollers 114 are provided, each feed roller 114 is provided so as to rotate independently by a separate motor. The feed rollers 114 may also be provided so as to rotate integrally by a common motor. A one-way clutch is provided between the feed roller 114 and the motor that applies a driving force to the feed roller 114 so as to restrict the rotation of the feed roller 114 in the direction opposite to the medium feeding direction A12.

[0028] The separation roller 115 is disposed in the first housing 101 facing the feed roller 114. The separation roller 115 is a so-called brake roller or retard roller, and is provided so as to be rotatable or stoppable in the direction A13 opposite to the medium feeding direction. The feed roller 114 and the separation roller 115 function as a separation unit that separates the medium, and separates the medium and feeds it one by one. The feed roller 114 is disposed above the separation roller 115, and the medium feeding device 100 feeds the medium by a so-called top-down method. Note that the feed roller 114 may be disposed below the separation roller 115, and the medium feeding device 100 may feed the medium by a so-called bottom-up method.

[0029] A torque limiter that specifies the limit value of the torque applied to the separation roller 115 is provided between the separation roller 115 and the motor that applies a driving force to the separation roller 115. The limit value of the torque limiter is set to a value such that the rotational force via the torque limiter is cut off when there is one medium, and the rotational force via the torque limiter is transmitted when there are multiple media. As a result, when only one medium is transported, the separation roller 115 does not rotate according to the driving force from the motor, but follows the feed roller 114. On the other hand, when multiple media are transported, the separation roller 115 rotates in the opposite direction A13 to the medium feeding direction, and separates the medium in contact with the feed roller 114 from the other media, thereby preventing double feeding. At this time, the outer circumferential surface of the separation roller 115 may apply a force in the opposite direction A13 to the medium feeding direction to the medium while it is stopped without rotating in the opposite direction A13 to the medium feeding direction.

[0030] The separation roller 115 is supported by the first housing 101 by an arm 115a. The separation roller 115 is attached to one end of the arm 115a, and the other end of the arm 115a is attached to the first housing 101. The arm 115a is provided to the first housing 101 so as to be rotatable (swingable). A biasing force is applied to the arm 115a by a biasing member (not shown) such as a spring member or a rubber member in the upward direction, that is, in the direction in which the separation roller 115 moves toward the feed roller 114 side. In addition, a rotational force for rotating (swinging) is applied to the arm 115a by a driving force from a motor (not shown). The medium feeding device 100 adjusts the pressing force with which the separation roller 115 presses the feed roller 114 by rotating (swinging) the arm 115a.

[0031] The second encoder 116 is an example of a third sensor. The second encoder 116 is provided on the shaft, which is the rotation axis of the separation roller 115, in the second housing 102, and detects the rotation of the separation roller 115. The second encoder 116 has a disk in which a large number of slits (light transmission holes) are formed and which is provided to rotate according to the rotation of the separation roller 115, and a light emitter and a light receiver which are provided to face each other across the disk. The light emitter is an LED or the like, and emits light toward the disk (light receiver). The light receiver is a photodiode or the like, and receives the light emitted by the light emitter through the disk. The light receiver detects the number of changes in a predetermined period from a state in which there is a slit between the light emitter and the light receiver to a state in which there is no slit and the light is blocked by the disk. The light receiver detects the movement distance of the outer circumferential surface of the separation roller 115 by multiplying the detected number of changes by the distance that the outer circumferential surface of the separation roller 115 moves when the disk rotates by the distance between two adjacent slits. In addition, a fixed slit is provided between the light emitter and the light receiver to make the output signal (pulse) two-phase, and the light receiver detects the rotation direction of the disk based on the rising timing of the output signal of each phase. The second encoder 116 generates and outputs a rotation signal indicating the detected moving distance and the rotation direction of the disk (stop / forward / reverse). Note that the second encoder 116 is not limited to an optical encoder, and may be any encoder such as a mechanical encoder, a magnetic encoder, or an electromagnetic induction encoder.

[0032] The second medium sensor 117 is an example of a second sensor. The second medium sensor 117 is disposed downstream of the feed roller 114 and the separation roller 115 and upstream of the first conveying roller 122a and the first driven roller 123a in the medium conveying direction A2, and detects the medium conveyed to the arrangement position. In particular, the second medium sensor 117 is disposed near the feed roller 114 and the separation roller 115. The second medium sensor 117 includes a light emitter and a light receiver provided on one side of the medium conveying path, and a light guide tube provided at a position facing the light emitter and the light receiver across the medium conveying path. The light emitter is an LED or the like, and emits light toward the medium conveying path. On the other hand, the light receiver is a photodiode or the like, and receives the light emitted by the light emitter and guided by the light guide tube. The second medium sensor 117 generates and outputs a second medium signal whose signal value changes depending on whether a medium is present or not at the position of the second medium sensor 117, based on the intensity of light received by the optical receiver.

[0033] The third medium sensor 118 is an example of a fourth sensor. The third medium sensor 118 is disposed downstream of the feed roller 114 and the separation roller 115 and upstream of the first conveyor roller 122a and the first driven roller 123a in the medium conveying direction A2, and detects the medium conveyed to the arrangement position. That is, the third medium sensor 118 is disposed between the feed roller 114 and the separation roller 115 and the first conveyor roller 122a and the first driven roller 123a in the medium conveying direction A2. In particular, the third medium sensor 118 is disposed downstream of the second medium sensor 117 in the medium conveying direction A2. The third medium sensor 118 includes a light emitter and a light receiver provided on one side of the medium conveying path, and a light guide tube provided at a position facing the light emitter and the light receiver across the medium conveying path. The light emitter is an LED 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. The third medium sensor 118 generates and outputs a third medium signal whose signal value changes depending on whether a medium is present or not at the position of the third medium sensor 118, based on the intensity of the light received by the light receiver.

[0034] The first skew sensor 119 and the second skew sensor 120 are disposed downstream of the feed roller 114 and the separation roller 115 and upstream of the first transport roller 122a and the first driven roller 123a in the medium transport direction A2, and detect the medium transported to their positions. In particular, the first skew sensor 119 and the second skew sensor 120 are disposed downstream of the third medium sensor 118 in the medium transport direction A2. The first skew sensor 119 and the second skew sensor 120 may be disposed upstream of the third medium sensor 118 in the medium transport direction A2. The first skew sensor 119 and the second skew sensor 120 are disposed at the same position in the medium transport direction A2 and arranged side by side with an interval in the width direction A4.

[0035] The first skew sensor 119 includes a light emitter and a light receiver provided on one side of the media transport path, and a light guide tube provided at a position facing the light emitter and the light receiver across the media transport path. The light emitter is an LED or the like, and emits light toward the media transport path. Meanwhile, the light receiver is a photodiode or the like, and receives the light emitted by the light emitter and guided by the light guide tube. The first skew sensor 119 generates and outputs a first skew signal, the signal value of which changes depending on whether a medium is present or not at the position of the first skew sensor 119, based on the intensity of the light received by the light receiver.

[0036] The second skew sensor 120 includes a light emitter and a light receiver provided on one side of the media transport path, and a light guide tube provided at a position facing the light emitter and the light receiver across the media transport path. The light emitter is an LED or the like, and emits light toward the media transport path. Meanwhile, the light receiver is a photodiode or the like, and receives the light emitted by the light emitter and guided by the light guide tube. The second skew sensor 120 generates and outputs a second skew signal whose signal value changes depending on whether a medium is present or not at the position of the second skew sensor 120, based on the intensity of the light received by the light receiver.

[0037] The ultrasonic sensor 121 is disposed downstream of the feed roller 114 and the separation roller 115 and upstream of the first conveyor roller 122a and the first driven roller 123a. The ultrasonic sensor 121 may be disposed downstream of the first conveyor roller 122a and the first driven roller 123a. The ultrasonic sensor 121 includes an ultrasonic transmitter 121a and an ultrasonic receiver 121b disposed in the vicinity of the medium conveying path and facing each other across the medium conveying path. The ultrasonic transmitter 121a emits ultrasonic waves. Meanwhile, the ultrasonic receiver 121b receives ultrasonic waves emitted by the ultrasonic transmitter 121a and passing through the medium, and generates and outputs an ultrasonic signal, which is an electrical signal corresponding to the received ultrasonic waves. The ultrasonic signal indicates the magnitude of the ultrasonic waves passing through the medium being fed.

[0038] The first to sixth conveying rollers 122a-f and the first to sixth driven rollers 123a-f are arranged facing each other downstream of the feed roller 114 and the separation roller 115 in the medium conveying direction A2. The first to sixth conveying rollers 122a-f and the first to sixth driven rollers 123a-f convey the medium fed by the feed roller 114 and the separation roller 115 downstream. The sixth conveying roller 122f and the sixth driven roller 123f discharge the medium to the discharge tray 104.

[0039] The fourth medium sensor 124 is disposed downstream of the first transport roller 122a and the first driven roller 123a and upstream of the second transport roller 122b and the second driven roller 123b in the medium transport direction A2, and detects the medium transported to the arrangement position. The fourth medium sensor 124 may be disposed downstream of the second transport roller 122b and the second driven roller 123b in the medium transport direction A2 and upstream of the imaging device 125. The fourth medium sensor 124 includes a light emitter and a light receiver provided on one side of the medium transport path, and a light guide tube provided at a position facing the light emitter and the light receiver across the medium transport path. The light emitter is an LED or the like, and emits light toward the medium transport path. On the other hand, the light receiver is a photodiode or the like, and receives the light emitted by the light emitter and guided by the light guide tube. The fourth medium sensor 124 generates and outputs a fourth medium signal whose signal value changes depending on whether a medium is present or not at the position of the fourth medium sensor 124, based on the intensity of light received by the optical receiver.

[0040] A reflective member such as a mirror may be used instead of a light guide in second medium sensor 117, third medium sensor 118, first skew sensor 119, second skew sensor 120 and / or fourth medium sensor 124. In each sensor, the light emitter and the light receiver may be disposed opposite each other with the medium transport path in between. Each sensor may detect the presence of the medium using a contact detection sensor or the like that passes a predetermined current when the medium is in contact or when the medium is not in contact.

[0041] The imaging device 125 is disposed downstream of the first and second transport rollers 122a-b in the medium transport direction A2, and captures images of the medium transported by the first and second transport rollers 122a-b and the first and second driven rollers 123a-b. The imaging device 125 includes a first imaging device 125a and a second imaging device 125b disposed opposite each other across the medium transport path. The first imaging device 125a is provided in the second housing 102, and the second imaging device 125b is provided in the first housing 101.

[0042] The first imaging device 125a has a line sensor using a CIS (Contact Image Sensor) of a life-size optical system type having imaging elements using CMOS (Complementary Metal Oxide Semiconductor) linearly arranged in the main scanning direction. The first imaging device 125a also has a lens that forms an image on the imaging elements, and an A / D converter that amplifies and analog-to-digital (A / D) converts the electrical signal output from the imaging elements. The first imaging device 125a captures an image of the surface of the medium being transported, generates an input image, and outputs it.

[0043] Similarly, the second imaging device 125b has a line sensor using a CIS of a life-size optical system type having CMOS imaging elements arranged in a line in the main scanning direction. The second imaging device 125b also has a lens that forms an image on the imaging element, and an A / D converter that amplifies and analog-to-digital (A / D) converts the electrical signal output from the imaging element. The second imaging device 125b captures the back side of the medium being transported to generate an input image and output it.

[0044] The medium feeding device 100 may have only one of the first imaging device 125a and the second imaging device 125b arranged to read only one side of the medium. Also, instead of a CIS line sensor of an equal magnification optical system type having a CMOS imaging element, a CIS line sensor of an equal magnification optical system type having a CCD (Charge Coupled Device) imaging element may be used. Also, a reduction optical system type line sensor having a CMOS or CCD imaging element may be used.

[0045] The medium placed on the placement table 103 is transported between the first guide 101a and the second guide 102a in the medium transport direction A2 by the rotation of the pick roller 113 and the feed roller 114 in the medium feed direction A11 and A12, respectively. The medium feeding device 100 has a separation mode in which the medium is separated while being fed, and a non-separation mode in which the medium is not separated while being fed. The feeding mode is set by the user using the operation device 105 or an information processing device that is communicatively connected to the medium feeding device 100. When the feeding mode is set to the separation mode, the separation roller 115 rotates or stops in the direction of the arrow A13, i.e., in the opposite direction to the medium feeding direction. This restricts the feeding of media other than the separated medium (prevention of double feeding). On the other hand, when the feeding mode is set to the non-separation mode, the separation roller 115 rotates in the opposite direction to the arrow A13, i.e., in the medium feeding direction.

[0046] While being guided by first guide 101a and second guide 102a, first and second transport rollers 122a-b rotate in the directions of arrows A14-15, thereby sending the medium to an imaging position of imaging device 125, and the medium is imaged by imaging device 125. Furthermore, the medium is discharged onto discharge tray 104 by third to sixth transport rollers 122c-f rotating in the directions of arrows A16-19, respectively.

[0047] 3(A) and (B) are schematic diagrams for explaining the first arm 131 and the second arm 132. Fig. 3(A) shows a schematic diagram of the periphery of the separation roller 115 of the first housing 101 seen from above with the second housing 102 open, and Fig. 3(B) shows a schematic diagram of the periphery of the feed roller 114 and the separation roller 115 seen from the side.

[0048] 3A and 3B, the medium feeding device 100 has a first arm 131 and a second arm 132. In the example shown in Fig. 3A and 3B, the separation rollers 115 are arranged at intervals in the width direction A4 perpendicular to the medium transport direction. In this case, the feed rollers 114 are also arranged at intervals in the width direction A4 perpendicular to the medium transport direction so as to face each separation roller 115.

[0049] The first arm 131 is a plate-like member extending along the medium transport direction A2, and is provided on the first housing 101 so as to be swingable (rotatable) in the height direction A1 around the upstream end 131a. The first arm 131 is disposed between the separation rollers 115 in the width direction A4 perpendicular to the medium transport direction. The first arm 131 has a first protrusion 131b. The first protrusion 131b is provided so as to be swingable so as to protrude from the first guide 101a, i.e., from the guide surface of the medium, and is disposed upstream of the nip portion N between the feed roller 114 and the separation roller 115 in the medium transport direction A2 in a state protruding from the first guide 101a.

[0050] The second arm 132 is a plate-like member extending along the medium conveying direction A2, and is provided in the first housing 101 so as to be swingable (rotatable) in the height direction A1 around the upstream end 132a. The second arm 132 is disposed between the separation rollers 115 in the width direction A4 perpendicular to the medium conveying direction. A gap is provided in the center of the second arm 132 in the width direction A4, and the first arm 131 is disposed in the center (gap) of the second arm 132 in the width direction A4. The second arm 132 has a second protrusion 132b. The second protrusion 132b is provided so as to be swingable so as to protrude from the first guide 101a, i.e., from the guide surface of the medium, and is disposed so as to overlap the nip portion N of the feed roller 114 and the separation roller 115 in the medium conveying direction A2 when protruding from the first guide 101a. That is, the second protrusion 132b is disposed downstream of the first protrusion 131b in the medium transport direction A2.

[0051] When the medium is returned from the downstream side to the upstream side, the medium is subjected to a pressing force from the pick roller 113 and the feed roller 114. This may cause the medium to buckle between the pick roller 113 and the feed roller 114, and may cause the separation roller 115 to slip, resulting in a medium jam. In response to this, the first protrusion 131b and the second protrusion 132b push up the center of the medium being fed in the width direction A4. This causes the medium being fed to bend in a wavy manner in the width direction A4, enabling the medium feeding device 100 to stiffen the medium and improve the rigidity of the medium moving along the medium transport direction A2.

[0052] Therefore, even when a thin paper having a low stiffness is returned from the downstream side to the upstream side, the medium feeding device 100 can suppress the occurrence of buckling of the medium and the occurrence of jamming of the medium. Also, even when a medium made of multiple sheets of paper such as an envelope or copy paper is returned from the downstream side to the upstream side, the medium has a rigidity that can withstand the separation force of the separation roller 115, so the medium feeding device 100 can suppress the occurrence of jamming of the medium. In particular, the medium feeding device 100 stiffens the medium in two stages using the first protrusion 131b and the second protrusion 132b that are arranged at different positions from each other in the medium conveying direction A2. As a result, the medium has a higher rigidity, so the medium feeding device 100 can suppress the occurrence of buckling or jamming of the medium.

[0053] FIG. 4 is a schematic diagram for explaining the pick roller 113. As shown in FIG.

[0054] As shown in FIG. 4, the medium feeding device 100 has an arm 133 that supports the pick roller 113. The arm 133 is provided in the second housing 102 so as to extend along the medium conveying direction A2 and be rotatable (swingable) about a downstream end 133a. The pick roller 113 is attached to an upstream end 133b of the arm 133. A biasing member 133c is attached to the upper part of the arm 133. The biasing member 133c is a spring member such as a torsion coil spring or a rubber member, and applies a downward biasing force to the arm 133. Note that the biasing member 133c may be omitted, and only a downward force due to its own weight may be applied to the arm 133. By biasing the arm 133 downward, the pick roller 113 can appropriately convey the medium while pressing the medium placed on the placement table 103 downward.

[0055] Further, a driving force from a motor (not shown) is applied to arm 133 to rotate (rotate) it upward. By rotating (swinging) arm 133, medium feeding device 100 can move pick roller 113 between a first position where pick roller 113 abuts against the medium placed on placement table 103 and a second position where pick roller 113 is separated from the medium placed on placement table 103. In this manner, pick roller 113 is provided to be movable between the first position and the second position.

[0056] FIG. 5 is a block diagram showing a schematic configuration of the medium feeding device 100. As shown in FIG.

[0057] In addition to the above-mentioned components, the medium feeding device 100 further includes a first motor 141, a second motor 142, a third motor 143, an interface device 144, a storage device 150, a processing circuit 160, and the like.

[0058] The first motor 141 includes one or more motors, and generates a driving force for rotating the feed roller 114 in the medium feed direction A12 in response to a control signal from the processing circuit 160, causing the feed roller 114 to feed the medium. When multiple feed rollers 114 are provided, a separate motor is provided for each feed roller 114 so that each feed roller 114 rotates independently. Note that the feed rollers 114 may be provided so as to rotate together with a common motor.

[0059] The second motor 142 is an example of a motor. The second motor 142 includes one or more motors, and generates a driving force for rotating the separation roller 115 in the direction A13 opposite to the medium feeding direction in response to a control signal from the processing circuit 160, causing the separation roller 115 to separate the medium.

[0060] The third motor 143 includes one or more motors, and rotates the pick roller 113 and the first to sixth transport rollers 122a-f to transport the medium in response to a control signal from the processing circuit 160. The first to sixth driven rollers 123a-f may be provided so as to rotate according to the driving force of the third motor 143, rather than being driven by the first to sixth transport rollers 122a-f. The third motor 143 also moves the placement table 103, oscillates the separation roller 115, or moves the pick roller 113 in response to a control signal from the processing circuit 160.

[0061] The interface device 144 has an interface circuit conforming to a serial bus such as USB, and is electrically connected to an information processing device (not shown, for example, a personal computer, a portable information terminal, etc.) to transmit and receive input images and various information. Also, instead of the interface device 144, a communication unit having an antenna for transmitting and receiving wireless signals and a wireless communication interface circuit for transmitting and receiving signals through a wireless communication line in accordance with a predetermined communication protocol may be used. The predetermined communication protocol is, for example, a wireless LAN (Local Area Network). The communication unit may have a wired communication interface circuit for transmitting and receiving signals through a wired communication line in accordance with a communication protocol such as a wired LAN.

[0062] The storage device 150 includes a memory device such as a random access memory (RAM) or a read only memory (ROM), a fixed disk device such as a hard disk, or a portable storage device such as a flexible disk or an optical disk. The storage device 150 also stores computer programs, databases, tables, and the like used for various processes of the medium feeding device 100. The computer programs may be installed in the storage device 150 from a computer-readable portable recording medium using a known setup program or the like. The portable recording medium is, for example, a compact disc read only memory (CD-ROM), a digital versatile disc read only memory (DVD-ROM), or the like.

[0063] The processing circuit 160 operates based on a program previously stored in the storage device 150. The processing circuit is, for example, a CPU (Central Processing Unit). The processing circuit 160 may be, for example, a DSP (digital signal processor), an LSI (large scale integration), an ASIC (Application Specific Integrated Circuit), or an FPGA (Field-Programmable Gate Array).

[0064] The processing circuit 160 is connected to the operation device 105, the display device 106, the first medium sensor 111, the first encoder 112, the second encoder 116, the second medium sensor 117, the third medium sensor 118, the first skew sensor 119, the second skew sensor 120, the ultrasonic sensor 121, the fourth medium sensor 124, the imaging device 125, the first motor 141, the second motor 142, the third motor 143, the interface device 144, the storage device 150, and the like, and controls each of these parts. The processing circuit 160 performs drive control of the first motor 141, the second motor 142, and the third motor 143, image capture control of the imaging device 125, and the like, based on signals received from each sensor. The processing circuit 160 acquires an input image from the imaging device 125, and transmits it to the information processing device via the interface device 144.

[0065] FIG. 6 is a diagram showing a schematic configuration of the storage device 150 and the processing circuit 160. As shown in FIG.

[0066] 6, the storage device 150 stores a control program 151, a skew determination program 152, an attachment determination program 153, and the like. Each of these programs is a functional module implemented by software that runs on a processor. The processing circuit 160 reads each program stored in the storage device 150 and operates according to the read program. In this way, the processing circuit 160 functions as a control unit 161, a skew determination unit 162, and an attachment determination unit 163.

[0067] 7 and 8 are flowcharts showing an example of the operation of the medium reading process of the medium feeding device 100. FIG.

[0068] An example of the operation of the medium reading process of the medium feeding device 100 will be described below with reference to the flowcharts shown in Figures 7 and 8. The flow of the operation described below is executed mainly by the processing circuit 160 in cooperation with each element of the medium feeding device 100 based on a program previously stored in the storage device 150. This flowchart describes the case where the feeding mode is set to the separation mode.

[0069] First, the control unit 161 waits until a user inputs an instruction to read a medium using the operation device 105 or an information processing device, and an operation signal instructing the user to read a medium is received from the operation device 105 or the interface device 144 (step S101).

[0070] Next, control unit 161 acquires a medium signal from first medium sensor 111, and determines whether or not a medium is placed on placement table 103 based on the acquired medium signal (step S102). If no medium is placed on placement table 103, control unit 161 ends the series of steps.

[0071] On the other hand, when a medium is placed on the placement table 103, the control unit 161 sets the skew flag to OFF (step S103). The skew flag is set to OFF every time a medium is fed, and is set to ON when it is determined in a skew determination process described below that a medium skew has occurred and the medium skew is corrected.

[0072] Next, the control unit 161 drives the third motor 143 to move the placement table 103 to a position where the medium can be fed, and places the pick roller 113 at the first position. The control unit 161 drives the third motor 143 to rotate the pick roller 113 in the medium feeding direction A11, and drives the first motor 141 to rotate the feed roller 114 in the medium feeding direction A12, thereby feeding the medium placed on the placement table 103. The control unit 161 drives the third motor 143 to rotate the first to sixth conveying rollers 122a to f, thereby conveying the medium placed on the placement table 103. Furthermore, the control unit 161 controls the second motor 142 to hold the separation roller 115 (step S104). The control unit 161 controls the second motor 142 to hold the separation roller 115 (to hold the stopped state) while energizing it.

[0073] If the separation roller 115 rotates in the opposite direction A13 to the medium feeding direction immediately after the start of feeding the medium, the medium waiting in the separation section is pushed out in the medium conveying direction A2 by the pick roller 113 and the feed roller 114 and pushed back by the separation roller 115. As a result, the medium waiting in the separation section vibrates as it repeatedly moves forward and backward, and the leading edge of the medium rises, making it easy for the medium to buckle or jam. In addition, a downward force is applied to the separation roller 115 by the pick roller 113 and the feed roller 114 through the medium waiting in the separation section. When a force to rotate in the opposite direction A13 to the medium feeding direction is applied to the separation roller 115, which is supported by the arm 115a so as to be swingable in the opposite direction A13 to the medium feeding direction, a downward moment acts on the separation roller 115, and the force pressing the separation roller 115 downward increases. This downward pushing force and the upward urging force from the urging member via arm 115a cause separation roller 115 to vibrate in height direction A1, making it easier for media to be fed in multiples (sloshing to the downstream side of the separation section).To address this, medium feeding device 100 holds separation roller 115 immediately after starting to feed the media, thereby preventing media jams and multiple feeds from occurring.

[0074] 9(A)-(C) and 10(A)-(C) are schematic diagrams for explaining the feeding of media placed on the placement table 103 with their leading edges not aligned. Figures 9(A)-(C) and 10(A)-(C) show an example in which multiple media are placed on the placement table 103 such that the leading edge of medium M2, which is placed below medium M1, is located downstream from the leading edge of medium M1, which is placed on the uppermost side.

[0075] Fig. 9(A) shows the state of each roller immediately after the start of feeding the medium. As shown in Fig. 9(A), immediately after the start of feeding the medium, the pick roller 113 and the feed roller 114 rotate in the medium feeding directions A11 and A12, respectively, and the separation roller 115 is held. Note that, as shown in Fig. 9(A), if multiple media have not yet reached the separation section, the separation roller 115 rotates in the medium feeding direction A13' following the feed roller 114 due to the action of a torque limiter provided in the separation roller 115. On the other hand, if the media have reached the separation section, the separation roller 115 is held under the control of the second motor 142.

[0076] Next, control unit 161 waits until second medium sensor 117 detects the leading edge of the medium (step S105). Control unit 161 periodically acquires a second medium signal from second medium sensor 117, and determines that second medium sensor 117 has detected the leading edge of the medium when the signal value of the second medium signal changes from a value indicating that no medium is present to a value indicating that a medium is present.

[0077] Next, the control unit 161 generates a driving force to rotate the separation roller 115 in the opposite direction A13 to the medium feeding direction, and controls the second motor 142 to rotate the separation roller 115 in the opposite direction A13 to the medium feeding direction (step S106). Hereinafter, the driving force to rotate the separation roller 115 in the opposite direction A13 to the medium feeding direction may be referred to as a separation driving force.

[0078] 9B shows a state in which the leading edge of the medium M2 arranged on the lower side has passed through the separation section. As shown in FIGS. 9A and 9B, the medium M2 arranged on the lower side, not the medium M1 to be fed, comes into contact with the feed roller 114, and the medium M2 is fed downstream by the feed roller 114. When the leading edge of the medium M2 passes through the separation section and the second medium sensor 117 detects the leading edge of the medium M2, a force is applied to the separation roller 115 to rotate in the direction A13 opposite to the medium feeding direction. However, due to the action of a torque limiter provided on the separation roller 115, the driving force from the second motor 142 is cut off, and the separation roller 115 rotates in the medium feeding direction A13' following the feed roller 114 without rotating according to the driving force from the second motor 142.

[0079] Next, the control unit 161 determines whether the separation roller 115 rotates in the direction A13 opposite to the medium feeding direction (step S107). The control unit 161 periodically receives a rotation signal from the second encoder 116. The control unit 161 determines whether the separation roller 115 rotates in the direction A13 opposite to the medium feeding direction based on the rotation direction indicated by the signal value of the received rotation signal.

[0080] The control unit 161 may further determine that the separation roller 115 is rotating in the opposite direction A13 to the medium feeding direction only when the movement distance indicated by the signal value of the received rotation signal, i.e., the movement distance of the outer circumferential surface of the separation roller 115, is equal to or greater than a predetermined distance. In this case, the control unit 161 determines that the separation roller 115 is rotating in the opposite direction A13 to the medium feeding direction only when the total movement distance when the signal value of the rotation signal indicates that the separation roller 115 is rotating in the opposite direction A13 to the medium feeding direction is equal to or greater than a predetermined distance. This makes it possible for the control unit 161 to suppress erroneous determination that a double feed of media has occurred when the separation roller 115 rotates in the opposite direction A13 to the medium feeding direction with a slight slip.

[0081] Fig. 9(C) shows a state in which the feeding of the medium continues from the state shown in Fig. 9(B). As shown in Fig. 9(C), when the medium M2 arranged on the lower side passes through the separation section first, the medium M1 arranged on the upper side (and the medium arranged between the medium M1 and the medium M2) is fed by the pick roller 113 and the feed roller 114 and passes through the separation section. When the medium M1 arranged on the upper side passes through the separation section, a plurality of media are present between the feed roller 114 and the separation roller 115, and the separation driving force from the second motor 142 is transmitted to the separation roller 115, and the separation roller 115 rotates in the direction A13 opposite to the medium feeding direction. As a result, the medium M2 in contact with the separation roller 115 is pushed back to the upstream side.

[0082] When the separation roller 115 rotates in the direction A13 opposite to the medium feeding direction, the control unit 161 determines that a double feed of media has occurred (step S108).

[0083] Next, the control unit 161 determines whether the skew flag is set to ON (step S109). If the skew flag is set to ON, the control unit 161 proceeds to step S115 without executing the processes of steps S110 to S112. That is, when the second encoder 116 detects the rotation of the separation roller 115 in the direction A13 opposite to the medium feeding direction during medium feeding, if medium skew occurs and the medium skew is being corrected, the control unit 161 does not stop the feeding roller 114. In this way, if medium skew occurs, the control unit 161 performs correction of the medium skew with priority. This allows the control unit 161 to prevent the medium from jamming due to the medium being conveyed at an angle and to prevent the medium from being chipped in the input image.

[0084] On the other hand, when the skew flag is set to OFF, the control unit 161 controls the first motor 141 to stop the feeding roller 114. The control unit 161 also controls the second motor 142 to generate a separation driving force and rotate the separation roller 115 in the direction A13 opposite to the medium feeding direction. The control unit 161 also controls the third motor 143 to stop the feeding of the medium by the pick roller 113 (step S110). For example, the control unit 161 stops the feeding of the medium by the pick roller 113 by controlling the third motor 143 to stop the rotation of the pick roller 113. Note that the control unit 161 may stop the feeding of the medium by the pick roller 113 by controlling the third motor 143 to move the pick roller 113 from the first position to the second position. In this case, the pick roller 113 is separated from the medium and does not hinder the movement of the medium to the upstream side, so that the medium feeding device 100 can return the medium to the upstream side more satisfactorily. In particular, when the medium being fed is thin paper, medium feeding device 100 can prevent the occurrence of medium jams and can prevent the occurrence of damage to the medium.

[0085] In this way, when the second encoder 116 detects rotation of the separation roller 115 in the direction A13 opposite to the medium feeding direction during medium feeding, the control unit 161 controls the second motor 142 to generate a separation driving force while stopping the feeding roller 114. Also, when the second encoder 116 detects rotation of the separation roller 115 in the direction A13 opposite to the medium feeding direction during medium feeding, the control unit 161 further stops the pick roller 113. Alternatively, when the second encoder 116 detects rotation of the separation roller 115 in the direction A13 opposite to the medium feeding direction during medium feeding, the control unit 161 further places the pick roller 113 at the second position.

[0086] Fig. 10(A) shows a state in which the pick roller 113 and the feed roller 114 are stopped from the state shown in Fig. 9(C). As shown in Fig. 10(A), stopping the pick roller 113 and the feed roller 114 stops the progress of the medium M1 arranged on the upper side. Meanwhile, the separation roller 115 rotates in the direction A13 opposite to the medium feeding direction, so that the medium in contact with the separation roller 115 is returned toward the upstream side. That is, first, the medium M2 in contact with the separation roller 115 is returned to the upstream side, and after the leading edge of the medium M2 returns to the upstream side from the separation section, the medium arranged above the medium M2 is sequentially returned to the upstream side.

[0087] If the medium is returned without stopping the pick roller 113 and the feed roller 114, when a large number of media are fed downstream of the separation section, some of the media may be fed to the position of the first conveyor roller 122a before all of the media are returned. If a medium is sandwiched between the first conveyor roller 122a and the first driven roller 123a, the medium will not return to the upstream side. The medium feeding device 100 can reliably prevent the occurrence of double feeding of media by stopping the pick roller 113 and the feed roller 114 until media other than the one to be fed are returned upstream of the separation section.

[0088] Note that the control unit 161 may stop the pick roller 113 or place it in the second position before the second encoder 116 detects the rotation of the separation roller 115 in the direction A13 opposite to the medium feeding direction during medium feeding. Even in this case, the medium feeding device 100 can reliably prevent the occurrence of double feeding of media.

[0089] Next, the control unit 161 waits until the second encoder 116 detects the stop of the separation roller 115 or until a predetermined time has elapsed since the feeding roller 114 was stopped (step S111). The predetermined time is determined in advance through a prior experiment as a time (e.g., 10 seconds) for the separation roller 115 to rotate an amount of rotation necessary for the separation roller 115 to return the maximum number of media that the medium feeding device 100 can feed due to overlapping to the upstream side of the separation unit.

[0090] Fig. 10(B) shows a state in which media other than the medium to be fed have returned upstream of the separation section from the state shown in Fig. 10(A). When all media other than medium M1 arranged on the upper side have returned upstream of the separation section as shown in Fig. 10(B), only medium M1 remains between feed roller 114 and separation roller 115. Due to the action of a torque limiter provided in separation roller 115, the driving force from second motor 142 is cut off, and separation roller 115 is stopped by stopped feed roller 114 without rotating according to the driving force from second motor 142.

[0091] Next, the control unit 161 drives the first motor 141 to rotate the feed roller 114 again in the medium feed direction A12, thereby causing the medium placed on the placement table 103 to be fed again (step S112).

[0092] Fig. 10(C) shows a state in which the feed roller 114 has been rotated again from the state shown in Fig. 10(B). As shown in Fig. 10(C), by rotating the feed roller 114 again, the medium M1 arranged on the upper side is fed again toward the downstream side, and the other media are kept in the separation section by the separation roller 115.

[0093] In this way, when the second encoder 116 detects that the separation roller 115 has stopped after the feed roller 114 has been stopped, the control unit 161 re-rotates the feed roller 114. By using the second encoder 116 to monitor the rotation of the separation roller 115, the control unit 161 can instantly and reliably detect that a medium other than the medium to be fed has returned upstream of the separation unit. This allows the control unit 161 to prevent the medium from being returned too far, causing a medium jam, and to shorten the total time required for the medium reading process.

[0094] Furthermore, when a predetermined time has elapsed after stopping the feed roller 114, the control unit 161 re-rotates the feed roller 114. By monitoring whether a predetermined time has elapsed since stopping the feed roller 114, the control unit 161 can appropriately continue the medium transport process even when wear on the surface of the separation roller 115 progresses and the separation roller 115 slips and is no longer able to return the medium to the upstream side.

[0095] Note that the control unit 161 re-rotates the feed roller 114 but does not re-rotate the pick roller 113. When the feeding of the medium to be fed is completed and feeding of the next medium is started, the control unit 161 re-rotates the pick roller 113 in step S104. This allows the control unit 161 to reduce the conveying force applied to the medium when re-feeding the medium, thereby preventing the re-occurrence of double feeding of the medium. Alternatively, the control unit 161 re-rotates the feed roller 114 but does not reposition the pick roller 113 to the first position. When the feeding of the medium to be fed is completed and feeding of the next medium is started, the control unit 161 re-positions the pick roller 113 to the first position in step S104. This allows the control unit 161 to reduce the frictional force applied between the media when re-feeding the medium, thereby preventing the re-occurrence of double feeding of the media.

[0096] Next, the control unit 161 proceeds to step S115 without returning the process to step S107. That is, when the second encoder 116 detects again the rotation of the separation roller 115 in the direction A13 opposite to the medium feeding direction after the control unit 161 resumes the rotation of the feed roller 114, the control unit 161 does not stop the feed roller 114. This allows the medium feeding device 100 to repeatedly move the medium forward and backward between the downstream side and the upstream side of the separation unit, thereby preventing the medium from jamming and / or being damaged.

[0097] On the other hand, if separation roller 115 has not rotated in the direction A13 opposite the medium feeding direction in step S107, control unit 161 determines whether third medium sensor 118 has detected the leading edge of the medium (step S113). Control unit 161 periodically acquires a third medium signal from third medium sensor 118, and determines that third medium sensor 118 has detected the leading edge of the medium when the signal value of the third medium signal changes from a value indicating a state in which no medium is present to a value indicating a state in which a medium is present. If third medium sensor 118 has not yet detected the leading edge of the medium, control unit 161 returns the process to step S107 and repeats the processes from step S107 onwards.

[0098] On the other hand, if the third medium sensor 118 detects the leading edge of the medium, the control unit 161 determines that a double feed of the medium has not occurred (step S114). In this case, the control unit 161 moves the process to step S115 without executing the processes of steps S110 to S112 thereafter. That is, the control unit 161 stops the feed roller 114 when the second encoder 116 detects the rotation of the separation roller 115 in the direction A13 opposite to the medium feeding direction during the medium feeding only during the period from when the second medium sensor 117 detects the leading edge of the medium until the third medium sensor 118 detects the leading edge of the medium. As a result, the control unit 161 does not return the medium to the upstream side after the medium is sandwiched between the first conveyor roller 122a and the first driven roller 123a, and therefore it is possible to prevent damage to the medium caused by forcibly returning the medium.

[0099] Next, control unit 161 waits until fourth medium sensor 124 detects the leading edge of the medium (step S115). Control unit 161 periodically acquires a fourth medium signal from fourth medium sensor 124, and determines that fourth medium sensor 124 has detected the leading edge of the medium when the signal value of the fourth medium signal changes from a value indicating that no medium is present to a value indicating that a medium is present.

[0100] Next, the control unit 161 controls the first motor 141 to stop the feed roller 114 (step S116). Thereafter, the medium is transported by the first transport roller 122a and the first driven roller 123a. By stopping the feed roller 114 after the medium has passed the position of the first transport roller 122a, the control unit 161 can prevent the medium from being pushed out by the feed roller 114 and bending, or from being pulled by the feed roller 114 and being damaged.

[0101] Next, the control unit 161 waits until the first encoder 112 detects the rear end of the medium (step S117). The control unit 161 periodically acquires a distance signal from the first encoder 112, and determines that the first encoder 112 has detected the rear end of the medium when the signal value of the distance signal changes from a value indicating that the medium is moving to a value indicating that the medium is not moving.

[0102] Next, the control unit 161 controls the second motor 142 to hold the separation roller 115 (step S118).

[0103] As described in steps S104 to S106, the control unit 161 controls the second motor 142 to hold the separation roller 115 from the start of feeding the medium until the second medium sensor 117 detects the leading edge of the medium. The control unit 161 also controls the second motor 142 to generate a driving force to rotate the separation roller 115 in the direction A13 opposite to the medium feeding direction from the time the second medium sensor 117 detects the leading edge of the medium until the first encoder 112 detects the trailing edge of the medium. This allows the control unit 161 to effectively separate the medium during feeding of the medium while suppressing the occurrence of a jam and a double feed of the medium immediately after the start of feeding of the medium. Note that the control unit 161 may control the second motor 142 to hold the separation roller 115 at any timing after the timing when the first encoder 112 detects the trailing edge of the medium, such as the timing when the second medium sensor 117 detects the trailing edge of the medium.

[0104] Next, the control unit 161 acquires an input image from the imaging device 125, and outputs the acquired input image by transmitting it to the information processing device via the interface device 144 (step S119). The control unit 161 causes the imaging device 125 to start imaging before the leading edge of the medium reaches the imaging position of the imaging device 125, such as at the timing when the fourth medium sensor 124 detects the leading edge of the medium. The control unit 161 also causes the imaging device 125 to end imaging after the trailing edge of the medium passes the imaging position of the imaging device 125, such as at the timing when a second predetermined time has elapsed since the fourth medium sensor 124 detected the trailing edge of the medium, and acquires the input image from the imaging device 125. The second predetermined time is set to a time taken for the medium to move from the fourth medium sensor 124 to the imaging position plus a margin.

[0105] Next, control unit 161 determines whether or not a medium remains on mounting table 103 based on the medium signal received from first medium sensor 111 (step S120). If a medium remains on mounting table 103, control unit 161 returns the process to step S103, and repeats the processes from step S103 onwards.

[0106] On the other hand, if there are no media remaining on the placement table 103, the control unit 161 controls the third motor 143 to stop the first to sixth transport rollers 122a to f (step S121), and ends the series of steps.

[0107] When the feeding mode is set to the non-separation mode, the processes of steps S103, S105 to S114, and S120 are omitted. In that case, in steps S104 and S118, the control unit 161 controls the separation roller 115 to rotate in response to the feeding roller 114, rather than holding the separation roller 115.

[0108] It should be noted that the process of step S109 or steps S115 to S116 may be omitted.

[0109] The control unit 161 may also receive a setting from the user as to whether or not to stop the feed roller 114 when a double feed of media occurs. In this case, the control unit 161 receives the setting input by the user using the operation unit 105 or the information processing device from the operation unit 105 or the interface unit 144. Even if the separation roller 115 rotates in the direction A13 opposite to the medium feeding direction in step S107, if the setting is made such that the feed roller 114 is not stopped when a double feed occurs, the control unit 161 does not stop the feed roller 114. When feeding media that are difficult to separate because of a high coefficient of friction, media bound with a pad, media with a sticker attached, etc., the user can set the feed roller 114 not to stop when a double feed of media occurs. This allows the medium feeding device 100 to suppress damage to the media caused by forcibly separating media that are difficult to separate or media that should not be separated.

[0110] The control unit 161 may also detect the setting state of the media on the placement table 103 and determine whether or not to stop the feed roller 114 when a double feed occurs based on the detected setting state. In this case, for example, an imaging device capable of imaging the leading edge (downstream edge) of the media placed on the placement table 103 is provided above the placement table 103. The control unit 161 detects the magnitude of misalignment of the leading edges of the media placed on the placement table 103 using a known image processing technique. If the detected magnitude of misalignment is equal to or less than a predetermined value (e.g., 30 mm), the control unit 161 stops the feed roller 114 when a double feed occurs. On the other hand, if the detected magnitude of misalignment is greater than the predetermined value, the control unit 161 does not stop the feed roller 114 when a double feed occurs, but notifies the user of the warning by sending information indicating a warning to the information processing device via the interface device 144. The medium feeding device 100 does not separate media that require a long time to separate, and instead asks the user to reset the media, thereby shortening the total time required for the medium reading process.

[0111] Furthermore, when it is detected in step S107 that the separation roller 115 is rotating in the direction A13 opposite to the medium feeding direction, the control unit 161 may change the pressure with which the separation roller 115 presses the feed roller 114. For example, the control unit 161 controls the third motor 143 to increase the pressure with which the separation roller 115 presses the feed roller 114. This allows the control unit 161 to increase the frictional force generated between the medium fed due to double feeding and the separation roller 115, thereby enabling the medium to be returned to the upstream side more effectively.

[0112] Furthermore, in step S112, when re-rotating the feed roller 114 to re-feed the medium, the control unit 161 may change the pressure with which the separation roller 115 presses the feed roller 114. For example, the control unit 161 controls the third motor 143 to reduce the pressure with which the separation roller 115 presses the feed roller 114. This allows the control unit 161 to increase the force with which the feed roller 114 and the separation roller 115 separate the media, thereby preventing the reoccurrence of double feeding of media.

[0113] Furthermore, in step S112, when re-rotating the feed roller 114 to re-feed the medium, the control unit 161 may change the circumferential speed of the feed roller 114. For example, the control unit 161 controls the first motor 141 to lower (slow) the circumferential speed of the feed roller 114. This enables the control unit 161 to increase the medium separation performance of the feed roller 114 and suppress the reoccurrence of double feeding of media.

[0114] FIG. 11 is a flowchart showing an example of the operation of the skew determination process of the medium feeding device 100.

[0115] An example of the operation of the skew determination process of the medium feeding device 100 will be described below with reference to the flowchart shown in Fig. 11. The flow of the operation described below is executed mainly by the processing circuit 160 in cooperation with each element of the medium feeding device 100 based on a program previously stored in the storage device 150. The flow of the operation shown in Fig. 11 is executed periodically during medium transport.

[0116] First, skew determining unit 162 receives a first skew signal and a second skew signal from first skew sensor 119 and second skew sensor 120, respectively, and stores each signal value of each received skew signal in storage device 150 (step S201).

[0117] Next, the skew determination unit 162 determines whether the skew condition is satisfied (step S202). The skew determination unit 162 determines whether the leading edge of the medium has reached the positions of the first skew sensor 119 and the second skew sensor 120. The skew determination unit 162 determines that the leading edge of the medium has reached the position of the first skew sensor 119 when the signal value of the first skew signal changes from a value indicating that the medium is not present to a value indicating that the medium is present. The skew determination unit 162 also determines that the leading edge of the medium has reached the position of the second skew sensor 120 when the signal value of the second skew signal changes from a value indicating that the medium is not present to a value indicating that the medium is present. The skew determination unit 162 determines that the skew condition is satisfied when the leading edge of the medium has reached one of the positions of the first skew sensor 119 and the second skew sensor 120 and has not reached the other position within a third predetermined time. The third specified time is set, for example, to the average, median, minimum or maximum value of the difference in the time at which the medium passes through each skew sensor when a medium jam occurs or a portion of the medium is missing in the input image, based on a prior experiment in which the medium is transported at an angle.

[0118] If the skew condition is not satisfied, the skew determining unit 162 determines that the medium skew has not occurred (step S203) and ends the series of steps. On the other hand, if the skew condition is satisfied, the skew determining unit 162 determines that the medium skew has occurred (step S204).

[0119] Next, the control unit 161 controls the multiple feed rollers 114 to correct the skew of the medium when the skew of the medium occurs (step S205). The control unit 161 corrects the skew of the medium by making the circumferential speeds of the feed rollers 114 different from one another. The control unit 161 changes the circumferential speed of each feed roller 114 so that the circumferential speed of the feed roller 114 arranged on the side where the progress of the medium is delayed in the width direction A4 is faster (higher) than the circumferential speed of the feed roller 114 arranged on the side where the progress of the medium is leading. The control unit 161 speeds up (increases) the circumferential speed of the feed roller 114 arranged on the side where the progress of the medium is lagging and / or slows down (decreases) the circumferential speed of the feed roller 114 arranged on the leading side.

[0120] Next, the skew determining unit 162 sets the skew flag to ON (step S206), and ends the series of steps.

[0121] 7, when the skew flag is set to ON, even if reverse rotation of the separation roller 115 (multiple feeding of media) occurs, the control unit 161 does not stop the feed roller 114. Therefore, the control unit 161 can appropriately correct the skew of the media.

[0122] FIG. 12 is a flowchart showing an example of the operation of the attachment determination process of the medium feeding device 100.

[0123] An example of the operation of the attachment determination process of the medium feeding device 100 will be described below with reference to the flowchart shown in Fig. 12. The flow of the operation described below is executed mainly by the processing circuit 160 in cooperation with each element of the medium feeding device 100 based on a program previously stored in the storage device 150. The flow of the operation shown in Fig. 12 is executed periodically during medium transport.

[0124] First, the attachment determination unit 163 acquires an ultrasonic signal from the ultrasonic sensor 121 (step S301). Next, the attachment determination unit 163 determines whether or not the signal value of the acquired ultrasonic signal is equal to or greater than an overlap threshold (step S302). The overlap threshold is set to a value between the signal value of the ultrasonic signal when one sheet of paper is being conveyed and the signal value of the ultrasonic signal when overlapped paper feed occurs.

[0125] When the signal value of the ultrasonic signal is equal to or greater than the overlap threshold, the attachment determination unit 163 does not execute any particular process and ends the series of steps. On the other hand, when the signal value of the ultrasonic signal is less than the overlap threshold, the attachment determination unit 163 determines that a sticker such as a sticky note or a label (seal) is attached to the medium (step S303). Next, the attachment determination unit 163 notifies the user by transmitting information indicating that a sticker is attached to the medium via the interface device 144 to the information processing device (step S304), and ends the series of steps. On the other hand, when the signal value of the ultrasonic signal does not become less than the overlap threshold before the rear end of the medium passes the ultrasonic sensor 121, the attachment determination unit 163 determines that no sticker is attached to the medium.

[0126] In this way, the attachment determination unit 163 determines whether or not a sticker is attached to the medium based on the ultrasonic signal. As described above, when a double feed of media occurs, the separation roller 115 rotates in the direction A13 opposite to the medium feeding direction, and the control unit 161 eliminates the double feed of media. Therefore, when an overlap of media is detected by the ultrasonic sensor 121 arranged downstream of the separation unit, the medium feeding device 100 can determine that a sticker is attached to the medium, rather than that a double feed of media has occurred.

[0127] As described above in detail, medium feeding device 100 holds separation roller 115 from when feeding of the medium starts until the leading edge of the medium passes through the separation section. Medium feeding device 100 reverses separation roller 115 after the leading edge of the medium passes through the separation section, and stops feeding roller 114 if multiple feeding of media occurs. This allows medium feeding device 100 to effectively separate media during feeding of the media while suppressing the occurrence of media jams and multiple feeding immediately after starting feeding of the media. Therefore, medium feeding device 100 is able to more appropriately feed media.

[0128] In particular, even if the leading edges of media set together on the mounting table 103 by a user are not aligned, the medium feeding device 100 can effectively separate the media while feeding the media, while preventing the occurrence of media jams and double feeding immediately after starting to feed the media. The user no longer needs to carefully align the media when setting multiple media together on the mounting table 103, and the medium feeding device 100 can improve user convenience.

[0129] Furthermore, when a duplicated medium feed occurs, the medium feeding device 100 does not reverse the pick roller 113 and the feed roller 114 to return all the media together, but returns the media one by one by the separation roller 115 without reversing the pick roller 113 and the feed roller 114. When the duplicated media are returned together with the leading ends not aligned, the leading ends of the returned media remain not aligned, so there is a high possibility that duplicated media will occur again when re-feeding. On the other hand, when the duplicated media are returned one by one with the leading ends not aligned, the leading ends of the returned media are aligned in front of the separation section, so there is a low possibility that duplicated media will occur again when re-feeding. When a duplicated medium feed occurs, the medium feeding device 100 returns the media one by one by the separation roller 115, so that duplicated media will not occur again when re-feeding.

[0130] Furthermore, when a double feed of media occurs, medium feeding device 100 does not reverse pick roller 113 and feed roller 114, so there is no need to disable the one-way clutch that limits the reverse rotation of pick roller 113 and feed roller 114. Therefore, medium feeding device 100 can simplify the control by control unit 161 for returning the media when a double feed of media occurs, and can suppress an increase in development costs for medium feeding device 100. Furthermore, medium feeding device 100 can suppress the occurrence of slight movement of pick roller 113 or feed roller 114 caused by disabling the one-way clutch, and as a result, can suppress the occurrence of media jams.

[0131] Furthermore, medium feeding device 100 does not use an ultrasonic sensor or a thickness sensor, but rather uses second encoder 116 that detects the rotation of separation roller 115 to determine whether or not a double feed of media has occurred. Therefore, even when a medium with an adhesive attached is fed, medium feeding device 100 does not erroneously determine that a double feed of media has occurred, and can accurately determine whether or not a double feed of media has occurred.

[0132] FIG. 13 is a diagram showing a schematic configuration of a processing circuit 260 of a medium feeding device according to another embodiment.

[0133] The processing circuit 260 is used in place of the processing circuit 160 of the medium feeding device 100, and executes the medium reading process and the like in place of the processing circuit 160. The processing circuit 260 has a control circuit 261, a skew determination circuit 262, an attachment determination circuit 263, and the like. Each of these components may be composed of an independent integrated circuit, microprocessor, firmware, and the like.

[0134] The control circuit 261 is an example of a control unit, and has the same functions as the control unit 161. The control circuit 261 receives an operation signal from the operation device 105 or the interface device 144. The control circuit 261 also receives a first medium signal, a second medium signal, a third medium signal, and a fourth medium signal from the first medium sensor 111, the second medium sensor 117, the third medium sensor 118, and the fourth medium sensor 124, respectively. The control circuit 261 also receives a distance signal and a rotation signal from the first encoder 112 and the second encoder 116, respectively. The control circuit 261 also reads out the skew determination result from the storage device 150. The control circuit 261 controls the first motor 141, the second motor 142, and the third motor 143 based on each received signal and / or each read information. The control circuit 261 also obtains an input image from the imaging device 125, and outputs it to the interface device 144.

[0135] The skew determination circuit 262 is an example of a skew determination section, and has the same function as the skew determination section 162. The skew determination circuit 262 receives a first skew signal and a second skew signal from the first skew sensor 119 and the second skew sensor 120, respectively. The skew determination circuit 262 determines whether or not a skew of the medium has occurred based on the received signals, and stores the determination result in the storage device 150.

[0136] The attachment determination circuit 263 is an example of an attachment determination section, and has the same function as the attachment determination section 163. The attachment determination circuit 263 receives an ultrasonic signal from the ultrasonic sensor 121. The attachment determination circuit 263 determines whether or not a sticker is attached to the medium based on the received ultrasonic signal, and outputs a warning to the interface device 144 according to the determination result.

[0137] As described above in detail, the medium feeding device is now able to more appropriately feed the medium even when the processing circuit 260 is used.

[0138] Although the preferred embodiments have been described above, the embodiments are not limited thereto. For example, the medium feeding device 100 may use another sensor instead of the second encoder 116 to detect the double feeding of the medium in the separation section. For example, the medium feeding device 100 detects the double feeding of the medium in the separation section using an ultrasonic sensor. In this case, an ultrasonic sensor similar to the ultrasonic sensor 121 is disposed at a position overlapping the nip portion of the feeding roller 114 and the separation roller 115 as viewed from the width direction A4. In step S107, the control unit 161 receives an ultrasonic signal from the ultrasonic sensor, and determines that the double feeding of the medium has occurred when the signal value of the received ultrasonic signal is less than the overlap threshold value.

[0139] Alternatively, the medium feeding device 100 may detect the double feeding of the medium in the separation unit based on the amount of current flowing through the second motor 142. In this case, a DC (Direct Current) motor is used as the second motor 142. Although the DC motor is low-cost and allows easy speed adjustment, the rotation speed of the DC motor varies depending on external factors such as load fluctuation. The lower the rotation speed of the motor, the greater the torque of the motor, and the greater the torque of the motor, the greater the amount of current flowing through the motor. In step S107, the control unit 161 receives the amount of current flowing through the second motor 142 from the second motor 142, and determines that the double feeding of the medium has occurred if the received amount of current is equal to or greater than the current threshold. The current threshold is set to the average, median, minimum, or maximum amount of current flowing through the DC motor when reverse rotation of the DC motor occurs, based on a prior experiment.

[0140] Alternatively, the medium feeding device 100 may use an optical sensor to detect the double feeding of the medium in the separation section. In this case, the optical sensor is arranged so as to image from below the area of ​​the medium being fed that overlaps with the nip portion of the feeding roller 114 and the separation roller 115 when viewed from the width direction A4. The optical sensor has a light emitter and a light receiver provided on the same side of the medium transport path, and detects the movement of the medium in the medium transport direction A2 and the width direction A4. The light emitter is an LED or the like, and emits light toward the transport path. The light receiver captures an image according to the light received at regular intervals, and detects a common portion between the latest image and the image immediately before. The light receiver calculates the movement direction and movement speed of the transported medium based on the change in position of the detected common portion in the image, and generates and outputs a movement signal indicating the calculated movement direction and movement speed. The regular period is, for example, a period corresponding to 100 operating pulses of the second motor 142. In step S107, the control unit 161 receives a movement signal from the optical sensor, and if the signal value of the received movement signal indicates that the medium is moving from the downstream side to the upstream side, it determines that a double feed of the medium is occurring.

[0141] Similarly, the medium feeding device 100 may use another sensor instead of the first encoder 112 to determine whether the trailing end of the medium has passed the position of the pick roller 113. For example, the medium feeding device 100 uses an optical sensor to determine whether the trailing end of the preceding medium has passed the position of the pick roller 113. In this case, the optical sensor is disposed so as to capture an image from above of an area of ​​the medium placed on the placement table 103 that overlaps with the nip portion of the pick roller 113 as viewed from the width direction A4. In step S117, the control unit 161 receives a movement signal from the optical sensor, and determines that the trailing end of the medium has passed the position of the pick roller 113 if the signal value of the received movement signal does not indicate that the medium is moving from the upstream side to the downstream side.

[0142] Furthermore, when the medium feeding device 100 uses the second encoder 116 to detect a double feed of media, the second encoder 116 may be used to execute functions other than determining whether a double feed of media has occurred. For example, when the medium feeding device 100 is started, the control unit 161 acquires a rotation signal from the second encoder 116 while controlling the second motor 142 to rotate the separation roller 115. If the signal value of the rotation signal indicates that the separation roller 115 is not rotating, the control unit 161 determines that the separation roller 115 has failed to be attached or has been forgotten to be attached, or that a malfunction has occurred in the separation roller 115 or the second encoder 116. Furthermore, when the medium feeding device 100 is started, the control unit 161 acquires a rotation signal from the second encoder 116 while controlling the first motor 141 to rotate the feed roller 114. When the signal value of the rotation signal indicates that the separation roller 115 is not rotating, the control unit 161 determines that the surface of the feed roller 114 or the separation roller 115 is dirty and that the frictional force between the feed roller 114 and the separation roller 115 is reduced. In these cases, the control unit 161 notifies the user of the warning by transmitting information indicating the warning to the information processing device via the interface device 144.

[0143] The control unit 161 may also determine whether the following medium has reached the separation unit when the preceding medium to be fed has passed through the separation unit based on the rotation signal from the second encoder 116. If the following medium has not reached the separation unit while the preceding medium is passing through the separation unit, the separation roller 115 rotates in the medium feeding direction following the feeding roller 114. On the other hand, if the following medium has reached the separation unit while the preceding medium is passing through the separation unit, the separation roller 115 is stopped or rotating in the opposite direction A13 to the medium feeding direction. Therefore, when the signal value of the rotation signal indicates that the separation roller 115 is rotating in the medium feeding direction, the control unit 161 determines that the following medium has not reached the separation unit. On the other hand, when the signal value of the rotation signal indicates that the separation roller 115 is stopped or rotating in the opposite direction A13 to the medium feeding direction, the control unit 161 determines that the following medium has reached the separation unit. When the control unit 161 determines that the following medium has reached the separation unit when the preceding medium to be fed has passed the separation unit, it delays, for example, the timing of feeding by the feeding roller 114 and the pick roller 113. In this way, the control unit 161 can sufficiently increase the distance between the two media fed in succession to prevent collisions between the media or image defects in the input image. [Explanation of symbols]

[0144] 100 medium feeding device, 103 placement table, 112 first encoder, 113 pick roller, 114 feeding roller, 115 separation roller, 116 second encoder, 117 second medium sensor, 118 third medium sensor, 122a first conveying roller, 131b first protrusion, 132b second protrusion, 142 second motor, 161 control unit, 162 skew determination unit

Claims

1. A feeding roller for feeding a medium, A separating roller disposed opposite to the feeding roller, A motor that generates a driving force for rotating the separating roller in a direction opposite to the medium feeding direction, A first sensor disposed upstream of the feeding roller and the separating roller in the medium conveyance direction, A second sensor disposed downstream of the feeding roller and the separating roller in the medium conveyance direction, A third sensor for detecting the rotation of the separating roller, A control unit for feeding the medium by rotating the feeding roller in the medium feeding direction, and having, The control unit, Controls the motor so as to hold the separating roller until the second sensor detects the leading end of the medium after starting the feeding of the medium, and controls the motor so as to generate the driving force from when the second sensor detects the leading end of the medium until the first sensor detects the trailing end of the medium, When the third sensor detects the rotation of the separating roller in the direction opposite to the medium feeding direction during the feeding of the medium, controls the motor to generate the driving force while stopping the feeding roller, A medium feeding device characterized by the above.

2. The control unit rotates the feeding roller again when the third sensor detects the stop of the separating roller after stopping the feeding roller. The medium feeding device according to Claim 1.

3. The control unit rotates the feeding roller again when a predetermined time has elapsed after stopping the feeding roller. The medium feeding device according to Claim 1 or 2.

4. When the third sensor redetects the rotation of the separating roller in the direction opposite to the medium feeding direction after restarting the rotation of the feeding roller, the control unit does not stop the feeding roller. The medium feeding device according to Claim 1 or 2.

5. Further includes a pick-up roller disposed upstream of the feeding roller and the separating roller in the medium conveyance direction, When the third sensor detects the rotation of the separating roller in the direction opposite to the medium feeding direction during the feeding of the medium, the control unit further stops the pick-up roller. The medium feeding device according to Claim 1 or 2.

6. A mounting table, A pick-up roller is further provided, which is disposed upstream of the feed roller and the separation roller in the medium conveyance direction, and is movable between a first position in contact with the medium placed on the mounting table and a second position spaced apart from the medium placed on the mounting table. The control unit further arranges the pick-up roller at the second position when the third sensor detects rotation of the separation roller in a direction opposite to the medium feed direction during feeding of the medium, according to claim 1 or 2 of the medium feeding device.

7. A conveyance roller disposed downstream of the feed roller and the separation roller in the medium conveyance direction, A fourth sensor disposed between the feed roller and the separation roller and the conveyance roller, is further provided. The control unit stops the feed roller when the third sensor detects rotation of the separation roller in a direction opposite to the medium feed direction during feeding of the medium, only during the period from when the second sensor detects the leading end of the medium to when the fourth sensor detects the leading end of the medium, according to claim 1 or 2 of the medium feeding device.

8. A plurality of the separation rollers are arranged at intervals in a direction orthogonal to the medium conveyance direction, A first protrusion portion disposed between the plurality of separation rollers in a direction orthogonal to the medium conveyance direction and swingably provided so as to protrude from the guide surface of the medium, A second protrusion portion disposed between the plurality of separation rollers in a direction orthogonal to the medium conveyance direction and downstream of the first protrusion portion in the medium conveyance direction, and swingably provided so as to protrude from the guide surface of the medium, is further provided, according to claim 1 or 2 of the medium feeding device.

9. A plurality of the feed rollers are arranged at intervals in a direction orthogonal to the medium conveyance direction, A skew determination unit for determining whether skew of the medium has occurred is further provided, The control unit, When skew of the medium has occurred, controls the plurality of feed rollers to correct the skew of the medium, When correcting the skew of the medium when the third sensor detects rotation of the separation roller in a direction opposite to the medium feed direction during feeding of the medium, does not stop the feed roller, according to claim 1 or 2 of the medium feeding device.

10. The medium is fed by rotating the feed roller in the medium feed direction. Control the motor so as to hold the separation roller until a second sensor disposed downstream of the feed roller and the separation roller disposed opposite to the feed roller in the medium conveyance direction detects the leading edge of the medium after starting the feeding of the medium, and control the motor so as to generate a driving force for rotating the separation roller in the direction opposite to the medium feeding direction from when the second sensor detects the leading edge of the medium until a first sensor disposed upstream of the feed roller and the separation roller in the medium conveyance direction detects the trailing edge of the medium. When a third sensor detects rotation of the separation roller in the direction opposite to the medium feeding direction during the feeding of the medium, control the motor so as to generate the driving force while stopping the feed roller. A medium feeding method characterized by the above. [

11. ] A control program for a medium feeding device having a feed roller for feeding a medium, a separation roller disposed opposite to the feed roller, a motor for generating a driving force for rotating the separation roller in the direction opposite to the medium feeding direction, a first sensor disposed upstream of the feed roller and the separation roller in the medium conveyance direction, a second sensor disposed downstream of the feed roller and the separation roller in the medium conveyance direction, and a third sensor for detecting rotation of the separation roller, Feed the medium by rotating the feed roller in the medium feeding direction. Control the motor so as to hold the separation roller until the second sensor detects the leading edge of the medium after starting the feeding of the medium, and control the motor so as to generate the driving force from when the second sensor detects the leading edge of the medium until the first sensor detects the trailing edge of the medium. When the third sensor detects rotation of the separation roller in the direction opposite to the medium feeding direction during the feeding of the medium, control the motor so as to generate the driving force while stopping the feed roller. A control program characterized by causing the medium feeding device to execute the above. [

12. ] A feed roller for feeding a medium, A separation roller disposed opposite to the feed roller, A motor for generating a driving force for rotating the separation roller in the direction opposite to the medium feeding direction, A rotation detection sensor for detecting rotation of the separation roller, A control unit for feeding the medium by rotating the feed roller in the medium feeding direction, and The control unit Start feeding the medium and then hold the separation roller, and then control the motor to generate the driving force. When the rotation detection sensor detects the rotation of the separation roller in the direction opposite to the medium feeding direction during the feeding of the medium, control the motor to generate the driving force while stopping the feeding roller. A medium feeding device characterized by the above.

13. Feed the medium by rotating the feeding roller in the medium feeding direction. Start feeding the medium and then hold the separation roller arranged opposite to the feeding roller, and then control the motor to generate a driving force for rotating the separation roller in the direction opposite to the medium feeding direction. When the rotation detection sensor detects the rotation of the separation roller in the direction opposite to the medium feeding direction during the feeding of the medium, control the motor to generate the driving force while stopping the feeding roller. A medium feeding method characterized by the above.

14. A control program for a medium feeding device having a feeding roller for feeding the medium, a separation roller arranged opposite to the feeding roller, a motor for generating a driving force for rotating the separation roller in the direction opposite to the medium feeding direction, and a rotation detection sensor for detecting the rotation of the separation roller. Feed the medium by rotating the feeding roller in the medium feeding direction. Start feeding the medium and then hold the separation roller, and then control the motor to generate the driving force. When the rotation detection sensor detects the rotation of the separation roller in the direction opposite to the medium feeding direction during the feeding of the medium, control the motor to generate the driving force while stopping the feeding roller. A control program characterized by causing the above to be executed by the medium feeding device.

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