Media transport device, control method, and control program

Abstract

To provide a media transport device, a control method, and a control program that can appropriately determine whether the inclination angle of a medium being transported changes.SOLUTION: A media transport device includes a transport roller, a first sensor disposed at the center of a medium transport path in a direction orthogonal to the medium transport direction, a second sensor disposed downstream of the first sensor in the medium transport direction and at the center of the medium transport path in a direction orthogonal to the medium transport direction, and a third sensor disposed downstream of the second sensor in the medium transport direction and on one side of the medium transport path in a direction orthogonal to the medium transport direction, and a determination portion that determines whether the inclination angle of the medium being transported has changed on the basis of a time from when the first sensor detects the medium until when the second sensor detects the medium when the first sensor detects the medium first, the third sensor detects the medium second, and the second sensor detects the medium third.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] In media transport devices such as scanners that capture images of media while transporting it, the inclination angle of the media may change during transport, resulting in the entire media not being captured, or the media may collide with the side wall of the transport path, causing a media jam (paper jam).

[0003] An image reading device is disclosed that includes a first detection unit, a second detection unit, and a third detection unit, and stops conveyance of a medium based on the detection results of the first detection unit, the second detection unit, and the third detection unit (see Patent Document 1). The first detection unit is located between a first position, which is a nip position between the feed roller and the separation roller, and a second position, which is a nip position between the pair of conveying rollers, in the medium conveying direction, and is provided so as to be located on both sides of the feed roller and the pair of conveying rollers in the medium width direction. The second detection unit is located between the first detection unit and the second position in the medium conveying direction, and is provided so as to be located on both sides of the feed roller and the pair of conveying rollers in the medium width direction. The third detection unit is located between the pair of second detection units in the medium width direction, downstream of the first position in the medium conveying direction, and upstream of the pair of second detection units. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-029816 A Summary of the Invention [Problem to be solved by the invention]

[0005] In a media transport device, it is required to appropriately determine whether the inclination angle of the medium is changing during transport in order to prevent the entire medium from being imaged or the medium from colliding with the side wall of the transport path and causing a media jam (paper jam).

[0006] An object of the present invention is to provide a medium transport device, a control method, and a control program that are capable of appropriately determining whether the tilt angle of a medium is changing during transport. [Means for solving the problem]

[0007] A media transport device according to one aspect of the present invention comprises a transport roller for transporting a medium, a first sensor arranged in the center of the media transport path in a direction perpendicular to the media transport direction, a second sensor arranged downstream of the first sensor in the media transport direction and in the center of the media transport path in a direction perpendicular to the media transport direction, a third sensor arranged downstream of the second sensor in the media transport direction and on one side of the media transport path in the direction perpendicular to the media transport direction, and a determination unit that determines whether the inclination angle of the medium being transported has changed based on the time from when the first sensor detects the medium to when the second sensor detects the medium when the first sensor detects the medium first, the third sensor detects the medium second, and the second sensor detects the medium third.

[0008] A media transport device according to one aspect of the present invention comprises a transport roller for transporting a medium, a first sensor arranged in the center of a media transport path in a direction perpendicular to the media transport direction, a second sensor arranged downstream of the first sensor in the media transport direction and on one side of the media transport path in a direction perpendicular to the media transport direction, a third sensor arranged downstream of the second sensor in the media transport direction and on one side of the media transport path in a direction perpendicular to the media transport direction, and a determination unit that determines whether the inclination angle of the medium being transported has changed based on the time from when one of the first and second sensors detects the medium first to when the third sensor detects the medium when one of the first and second sensors detects the medium second, and the third sensor detects the medium third.

[0009] A media transport device according to one aspect of the present invention comprises a transport roller for transporting a medium, a central sensor arranged in the center of the media transport path in a direction perpendicular to the media transport direction, a side sensor arranged downstream of the central sensor in the media transport direction and on one side of the media transport path in a direction perpendicular to the media transport direction, and a determination unit for determining whether the inclination angle of the medium during transport has changed, wherein at least one of the central sensor and the side sensor includes two sensors arranged at different positions from each other in the media transport direction, and the determination unit determines whether the inclination angle of the medium during transport has changed based on which sensor detected the medium first, the sensor detected the medium second, and the sensor detected the medium third, and the time from when the sensor that first detected the medium detected the medium to when the sensor that third detected the medium detected the medium.

[0010] A control method according to one aspect of the present invention is a control method for a media transport device having a transport roller for transporting a medium, a first sensor arranged in the center of the media transport path in a direction perpendicular to the media transport direction, a second sensor arranged downstream of the first sensor in the media transport direction and in the center of the media transport path in a direction perpendicular to the media transport direction, and a third sensor arranged downstream of the second sensor in the media transport direction and on one side of the media transport path in the direction perpendicular to the media transport direction, wherein when the first sensor detects the medium first, the third sensor detects the medium second, and the second sensor detects the medium third, a determination is made as to whether the inclination angle of the medium being transported has changed based on the time from when the first sensor detects the medium to when the second sensor detects the medium.

[0011] A control method according to one aspect of the present invention is a control method for a media transport device having a transport roller that transports a medium, a first sensor arranged in the center of the media transport path in a direction perpendicular to the media transport direction, a second sensor arranged downstream of the first sensor in the media transport direction and on one side of the media transport path in a direction perpendicular to the media transport direction, and a third sensor arranged downstream of the second sensor in the media transport direction and on one side of the media transport path in the direction perpendicular to the media transport direction, wherein when one of the first and second sensors detects the medium first, the other of the first and second sensors detects the medium second, and the third sensor detects the medium third, it is determined whether the inclination angle of the medium being transported has changed based on the time from when one sensor detects the medium to when the third sensor detects the medium.

[0012] A control method according to one aspect of the present invention is a control method for a media transport device having a transport roller that transports a medium, a central sensor arranged in the center of the media transport path in a direction perpendicular to the media transport direction, and a side sensor arranged downstream of the central sensor in the media transport direction and on one side of the media transport path in a direction perpendicular to the media transport direction, where at least one of the central sensor and the side sensor includes two sensors arranged at different positions from each other in the media transport direction, and determines whether the inclination angle of the medium during transport is changing based on which sensor first detects the medium, the sensor second detects the medium, and the sensor third detects the medium, and the time from when the sensor first detects the medium to when the sensor third detects the medium.

[0013] A control program according to one aspect of the present invention is a control program for a media transport device having a transport roller for transporting a medium, a first sensor arranged in the center of the media transport path in a direction perpendicular to the media transport direction, a second sensor arranged downstream of the first sensor in the media transport direction and in the center of the media transport path in a direction perpendicular to the media transport direction, and a third sensor arranged downstream of the second sensor in the media transport direction and on one side of the media transport path in the direction perpendicular to the media transport direction, and when the first sensor detects the medium first, the third sensor detects the medium second, and the second sensor detects the medium third, the control program causes the media transport device to determine whether the inclination angle of the medium being transported has changed based on the time from when the first sensor detects the medium to when the second sensor detects the medium.

[0014] A control program according to one aspect of the present invention is a control program for a media transport device having a transport roller for transporting a medium, a first sensor arranged in the center of the media transport path in a direction perpendicular to the media transport direction, a second sensor arranged downstream of the first sensor in the media transport direction and on one side of the media transport path in a direction perpendicular to the media transport direction, and a third sensor arranged downstream of the second sensor in the media transport direction and on one side of the media transport path in a direction perpendicular to the media transport direction, and causes the media transport device to determine whether the inclination angle of the medium being transported has changed based on the time from when one sensor detects the medium to when the third sensor detects the medium when one of the first and second sensors detects the medium first, the other of the first and second sensors detects the medium second, and the third sensor detects the medium third.

[0015] A control program according to one aspect of the present invention is a control program for a media transport device having a transport roller for transporting a medium, a central sensor arranged in the center of the media transport path in a direction perpendicular to the media transport direction, and a side sensor arranged downstream of the central sensor in the media transport direction and on one side of the media transport path in a direction perpendicular to the media transport direction, wherein at least one of the central sensor and the side sensor includes two sensors arranged at different positions from each other in the media transport direction, and causes the media transport device to determine whether the inclination angle of the medium during transport has changed based on which sensor detected the medium first, which sensor detected the medium second, and which sensor detected the medium third, and the time from when the sensor that first detected the medium detected the medium to when the sensor that third detected the medium detected the medium. Effect of the Invention

[0016] According to the present invention, the medium transport device, the control method, and the control program are capable of appropriately determining whether the skew angle of the medium is changing during transport. [Brief description of the drawings]

[0017] [Figure 1] 1 is a perspective view showing a medium conveying device 100 according to an embodiment. [Diagram 2] 2 is a diagram for explaining a transport path inside the medium transport device 100. FIG. [Diagram 3] FIG. 2 is a schematic diagram for explaining each sensor. [Figure 4] 1 is a block diagram showing a schematic configuration of a medium conveying device 100. FIG. [Diagram 5] FIG. 13 illustrates an example of a data structure of a cumulative skew condition table. [Figure 6] 1A and 1B are schematic diagrams for explaining cumulative skew. [Figure 7] FIG. 13 illustrates an example of a data structure of an abnormal skew condition table. [Figure 8] 13A and 13B are schematic diagrams for explaining anomalous skew. [Figure 9] FIG. 2 is a diagram showing a schematic configuration of a storage device 140 and a processing circuit 150. [Figure 10] 10 is a flowchart illustrating an example of the operation of a medium reading process. [Figure 11] 10 is a flowchart illustrating an example of the operation of a medium reading process. [Figure 12] 13A and 13B are schematic diagrams showing a state in which the edge of the medium passes the position of the outside-area sensor 115. FIG. [Figure 13] FIG. 13A is a diagram showing an example of the data structure of another cumulative skew condition table, and FIG. 13B is a diagram showing an example of the data structure of another abnormal skew condition table. [Figure 14] FIG. 1A is a schematic diagram for explaining cumulative skew, and FIG. 1B is a schematic diagram for explaining anomalous skew. [Figure 15] FIG. 1A is a schematic diagram for explaining cumulative skew, and FIG. 1B is a schematic diagram for explaining anomalous skew. [Figure 16]FIG. 13A is a diagram showing an example of the data structure of another cumulative skew condition table, and FIG. 13B is a diagram showing an example of the data structure of another abnormal skew condition table. [Figure 17] FIG. 13A is a diagram showing an example of the data structure of another cumulative skew condition table, and FIG. 13B is a diagram showing an example of the data structure of another abnormal skew condition table. [Figure 18] FIG. 13 is a diagram showing a schematic configuration of a processing circuit 250 according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, a medium conveying device, a control 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.

[0019] 1 is a perspective view showing a medium conveying device 100 configured as an image scanner. The medium conveying device 100 conveys a medium, which is an original document, and captures an image of the medium. The medium is paper, cardboard, a card, a booklet, a passport, or the like. The medium conveying device 100 may be a facsimile, a copier, a multifunction printer (MFP, Multifunction Peripheral), or the like. Note that the medium being conveyed may not be an original document, but may be a print target, or the like, and the medium conveying device 100 may be a printer, or the like.

[0020] 1, arrow A1 indicates the medium transport direction, and arrow A2 indicates the width direction perpendicular to the medium transport direction. In the following, upstream refers to the upstream side in the medium transport direction A1, and downstream refers to the downstream side in the medium transport direction A1.

[0021] The medium conveying device 100 includes a lower housing 101, an upper housing 102, a placement table 103, a discharge table 104, an operation device 105, a display device 106, and the like.

[0022] The upper housing 102 is disposed in a position that covers the top surface of the medium conveying device 100, and engages with the lower housing 101 by a hinge so that it can be opened and closed when the medium is jammed or when the inside of the medium conveying device 100 is cleaned.

[0023] The placement table 103 engages with the lower housing 101. The placement table 103 has a placement surface 103a on which the medium is placed, and places the medium to be fed and transported. A side guide 103b is provided on the placement surface 103a so as to be movable in a width direction A2 perpendicular to the medium transport direction. The side guide 103b is positioned according to the width of the medium placed on the placement table 103, and regulates the width direction of the medium. In the example shown in FIG. 1, two side guides 103b are arranged with a gap between them so that the medium is located at the center in the width direction A2. Only one side guide 103b may be arranged so that the medium is located at one end in the width direction A2.

[0024] The ejection platform 104 engages with the upper housing 102 and places the ejected media thereon. The ejection platform 104 may be provided to engage with the lower housing 101.

[0025] 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 input operation by the user. 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.

[0026] FIG. 2 is a diagram for explaining a transport path inside the medium transport device 100. As shown in FIG.

[0027] The transport path inside the media transport device 100 includes a placement sensor 111, a feed roller 112, a separation roller 113, a first central sensor 114, an out-of-area sensor 115, a second central sensor 116, a first side sensor 117, a thickness sensor 118, a second side sensor 119, a first transport roller 120, a second transport roller 121, a third side sensor 122, an imaging device 123, a third transport roller 124 and a fourth transport roller 125, etc.

[0028] The feed roller 112, the separation roller 113, the first conveyor roller 120, the second conveyor roller 121, the third conveyor roller 124, and / or the fourth conveyor roller 125 are examples of conveyor rollers that convey a medium. The number of each of the feed roller 112, the separation roller 113, the first conveyor roller 120, the second conveyor roller 121, the third conveyor roller 124, and / or the fourth conveyor roller 125 is not limited to one, and may be more than one. In this case, the multiple feed rollers 112, the separation roller 113, the first conveyor roller 120, the second conveyor roller 121, the third conveyor roller 124, and / or the fourth conveyor roller 125 are arranged at intervals in the width direction A2.

[0029] The medium conveying device 100 has a so-called straight path. The top surface of the lower housing 101 forms a lower guide 101a of the medium conveying path, and the bottom surface of the upper housing 102 forms an upper guide 102a of the medium conveying path.

[0030] The placement sensor 111 is disposed upstream of the feed roller 112 and the separation roller 113. The placement sensor 111 has a contact detection sensor, and detects whether or not a medium is placed on the placement table 103. The placement sensor 111 generates and outputs a placement signal whose signal value changes depending on whether or not a medium is placed on the placement table 103. Note that the placement 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 placement sensor 111.

[0031] The feed rollers 112 are provided in the lower housing 101, and separate and feed the media placed on the placement table 103 in order from the bottom up. Each feed roller 112 is provided so as to rotate independently by a separate motor. The feed rollers 112 may be provided so as to rotate integrally by a common motor. The separation roller 113 is a so-called brake roller or retard roller, and is provided in the upper housing 102, disposed opposite the feed roller 112, and rotates in the opposite direction to the medium feeding direction. The separation roller 113 is provided so as to be rotatable or stoppable in the direction A4 opposite to the medium feeding direction.

[0032] The thickness sensor 118 is disposed downstream of the feed roller 112 and the separation roller 113 and upstream of the first conveyor roller 120 and the second conveyor roller 121. In the example shown in FIG. 2, the thickness sensor 118 is disposed downstream of the first side sensor 117 and upstream of the second side sensor 119. The thickness sensor 118 may be disposed at any position on the medium conveyance path. The thickness sensor 118 is an ultrasonic sensor and includes an ultrasonic transmitter 118a and an ultrasonic receiver 118b. The ultrasonic transmitter 118a and the ultrasonic receiver 118b are disposed near the medium conveyance path and facing each other across the conveyance path. The ultrasonic transmitter 118a emits ultrasonic waves. Meanwhile, the ultrasonic receiver 118b receives ultrasonic waves emitted by the ultrasonic transmitter 118a and transmitted through the medium, and generates and outputs a thickness signal, which is an electrical signal corresponding to the received ultrasonic waves. The ultrasonic waves transmitted through the medium are also attenuated by the medium itself, and the thicker the medium through which they pass, the greater the amount of attenuation. Therefore, the medium conveying device 100 can detect the thickness of the conveyed medium based on the thickness signal. Furthermore, when multiple media are conveyed in an overlapping state, ultrasonic waves passing through the media are attenuated by the air layer between the overlapping media. Therefore, the medium conveying device 100 can detect the double feeding of media based on the thickness signal.

[0033] The thickness sensor 118 may be, for example, a reflective light sensor including a pair of a light emitter and a light receiver provided on one side of the medium transport path and a pair of a light emitter and a light receiver provided on the other side. The reflective light sensor detects the distance between each pair and each side of the medium from the time from when one pair irradiates one side of the medium with light to when it receives the reflected light and the time from when the other pair irradiates the other side of the medium with light to when it receives the reflected light. The reflective light sensor generates a thickness signal indicating the difference value obtained by subtracting each detected distance from the distance between the two pairs as the thickness. The thickness sensor 118 may be a pressure sensor that detects the pressing force applied by the transported medium and generates and outputs a thickness signal indicating the detected pressing force as the thickness. The thickness sensor 118 may also be a movement amount sensor that detects the amount of movement of a contact piece that contacts the transported medium and generates and outputs a thickness signal indicating the detected amount of movement as the thickness.

[0034] The first transport roller 120 and the second transport roller 121 are disposed downstream of the feed roller 112 and facing each other, and transport the medium fed by the feed roller 112 and the separation roller 113 to the imaging device 123. The first transport roller 120 is provided in the upper housing 102, and the second transport roller 121 is provided in the lower housing 101 below the first transport roller 120. The first transport rollers 120 and / or the second transport rollers 121 are provided so as to rotate together by a common motor. The first transport rollers 120 and / or the second transport rollers 121 may be provided so as to rotate independently by separate motors. Either one of the first transport rollers 120 and the second transport rollers 121 may be a driven roller that rotates following the other roller.

[0035] The imaging device 123 is disposed downstream of the first conveying roller 120 and the second conveying roller 121, and captures an image of the medium conveyed by the first conveying roller 120 and the second conveying roller 121. The imaging device 123 includes a first imaging device 123a and a second imaging device 123b disposed opposite each other across the medium conveying path. The first imaging device 123a has a line sensor based on a CIS (Contact Image Sensor) of a life-size optical system type having imaging elements based on CMOS (Complementary Metal Oxide Semiconductor) linearly arranged in the main scanning direction. The first imaging device 123a also has a lens that forms an image on the imaging element, and an A / D converter that amplifies and analog-to-digital (A / D) converts the electrical signal output from the imaging element. The first imaging device 123a captures an image of the surface of the medium being conveyed, generates an input image, and outputs it, according to control from a processing circuit described later.

[0036] Similarly, the second imaging device 123b 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 123b 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 123b captures the back side of the medium being conveyed under the control of a processing circuit described later, generates an input image, and outputs it.

[0037] The medium conveying device 100 may have only one of the first imaging device 123a and the second imaging device 123b arranged, and may 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.

[0038] The third conveying roller 124 and the fourth conveying roller 125 are disposed downstream of the imaging device 123 and facing each other, and discharge the medium conveyed by the first conveying roller 120 and the second conveying roller 121 and imaged by the imaging device 123 to the discharge tray 104. The third conveying roller 124 is provided in the upper housing 102, and the fourth conveying roller 125 is provided in the lower housing 101 below the third conveying roller 124. The third conveying rollers 124 and / or the fourth conveying rollers 125 are provided so as to rotate together by a common motor. The third conveying rollers 124 and / or the fourth conveying rollers 125 may be provided so as to rotate independently by separate motors. Either one of the third conveying rollers 124 and the fourth conveying rollers 125 may be a driven roller that rotates following the other roller.

[0039] The medium placed on the placement table 103 is conveyed between the lower guide 101a and the upper guide 102a in the medium conveying direction A1 by the rotation of the feed roller 112 in the direction of the arrow A3 in FIG. 2, i.e., the medium feeding direction. The medium conveying 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 feed mode is set by the user using the operation device 105 or an information processing device that is communicatively connected to the medium conveying device 100. When the feed mode is set to the separation mode, the separation roller 113 rotates or stops in the direction of the arrow A4, i.e., the opposite direction to the medium feeding direction, during medium conveyance. This limits the conveyance of media other than the separated media (prevention of double feeding). On the other hand, when the feed mode is set to the non-separation mode, the separation roller 113 rotates in the opposite direction of the arrow A4, i.e., the medium feeding direction.

[0040] The medium is fed between the first conveyor roller 120 and the second conveyor roller 121 while being guided by the lower guide 101a and the upper guide 102a. The medium is fed between the first imaging device 123a and the second imaging device 123b as the first conveyor roller 120 and the second conveyor roller 121 rotate in the directions of the arrows A5 and A6, respectively. The medium read by the imaging device 123 is discharged onto the discharge tray 104 as the third conveyor roller 124 and the fourth conveyor roller 125 rotate in the directions of the arrows A7 and A8, respectively.

[0041] FIG. 3 is a schematic diagram for explaining each sensor for detecting the medium.

[0042] 3, the number of each of the feed rollers 112, separation rollers 113, first conveyor rollers 120, second conveyor rollers 121, third conveyor rollers 124, and fourth conveyor rollers 125 is two. The number of each of the first central sensor 114 and second central sensor 116 is one, and the number of each of the outside area sensors 115, first side sensor 117, second side sensor 119, and third side sensor 122 is two. The number of the first central sensor 114, outside area sensor 115, second central sensor 116, first side sensor 117, second side sensor 119, and / or third side sensor 122 may be any number.

[0043] The first central sensor 114 is an example of a first sensor and a central sensor arranged in the center of the medium transport path in a direction perpendicular to the medium transport direction, and detects the medium transported to the arrangement position. The first central sensor 114 is arranged downstream of the feed roller 112 and the separation roller 113 in the medium transport direction A1, and in the center of the medium transport path in the width direction A2 perpendicular to the medium transport direction. In particular, the first central sensor 114 is arranged downstream of the nip portion N1 between the feed roller 112 and the separation roller 113 and upstream of the nip portion N2 between the first transport roller 120 and the second transport roller 121 in the medium transport direction A1. In addition, the first central sensor 114 is arranged between the multiple outside area sensors 115, between the multiple first side sensors 117, between the second side sensors 119, and / or between the multiple third side sensors 122 in the width direction A2. The first central sensor 114 is disposed between the multiple feed rollers 112 (nip portion N1), between the multiple first conveyor rollers 120 (nip portion N2), and / or between the multiple third conveyor rollers 124 (nip portion N3 between the third conveyor roller 124 and the fourth conveyor roller 125) in the width direction A2. In the example shown in Fig. 3, the first central sensor 114 is disposed near the nip portion N1 between the feed roller 112 and the separation roller 113 in the medium conveying direction A1, and at the center position of the medium conveying path in the width direction A2.

[0044] The first central sensor 114 includes a light emitter 114a and a light receiver 114b provided on one side of the medium transport path, and a light guide tube provided at a position facing the light emitter 114a and the light receiver 114b across the medium transport path. The light emitter 114a is an LED (Light Emitting Diode) or the like, and emits light toward the medium transport path. On the other hand, the light receiver 114b is a photodiode or the like, and receives the light emitted by the light emitter 114a and guided by the light guide tube. When a medium is present at a position facing at least one of the light emitter 114a and the light receiver 114b, the light emitted from the light emitter 114a is blocked by the medium, and therefore the light receiver 114b does not detect the light emitted from the light emitter 114a. The first central sensor 114 generates and outputs a first central signal whose signal value changes depending on whether a medium is present or not at the position of the first central sensor 114, based on the intensity of light received by the light receiver 114b.

[0045] The light emitter 114a and the light receiver 114b are arranged side by side with a gap in the medium conveying direction A1 so that they are arranged at the same position in the width direction A2. When the light emitter 114a and the light receiver 114b are arranged at different positions in the width direction A2, which of the light emitter 114a and the light receiver 114b the medium passes through first depends on the inclination of the medium. On the other hand, when the light emitter 114a and the light receiver 114b are arranged at the same position in the width direction A2, the medium is likely to pass through the upstream position of the light emitter 114a and the light receiver 114b first, regardless of the inclination. Therefore, the medium conveying device 100 can accurately identify the timing when the end of the medium passes a specific position in the width direction A2 (the upstream position of the light emitter 114a and the light receiver 114b). Furthermore, by arranging the light emitter 114a and the light receiver 114b at the same position in the width direction A2, particularly at the center position, errors in the detection timing of the medium due to manufacturing errors in the arrangement positions of the light emitter 114a, the light receiver 114b and / or their light passage holes are reduced. Therefore, the medium conveying device 100 can more accurately detect the degree of tilt of the medium using the first central sensor 114 and the multiple first side sensors 117 or multiple second side sensors 119 arranged outside the first central sensor 114. Note that the light emitter 114a and the light receiver 114b may be arranged side by side with a gap in between in the width direction A2 so that they are arranged at different positions in the width direction A2.

[0046] The outside-area sensor 115 detects the medium transported to its arrangement position. In the example shown in FIG. 3, two outside-area sensors 115 are arranged side by side with a gap in the width direction A2. The outside-area sensors 115 are arranged downstream of the feed roller 112 and the separation roller 113 in the medium transport direction A1, particularly downstream of the first central sensor 114, and on both sides of the medium transport path in the width direction A2 perpendicular to the medium transport direction. In particular, the outside-area sensor 115 is arranged upstream of the imaging device 123 in the medium transport direction A1, particularly upstream of the nip portion N2 between the first transport roller 120 and the second transport roller 121. The outside-area sensor 115 is also arranged inside (to the center) the side wall 101b of the medium transport path in the width direction A2. The outside-area sensor 115 is disposed in the width direction A2 outside (towards the side wall 101b) of a medium of the maximum size supported by the medium conveying device 100 when the medium is placed on the placement table 103, that is, outside the position of the inner side surface of the side guide 103b when it is disposed at the outermost position. The outside-area sensor 115 is also disposed in the width direction A2 outside the end position of the imaging range of the imaging device 123. The outside-area sensor 115 may be disposed inward from the end position of the imaging range of the imaging device 123 in the width direction A2.

[0047] The outside-area sensor 115 includes a light emitter 115a and a light receiver 115b provided on one side of the medium transport path, and a light guide tube provided at a position facing the light emitter 115a and the light receiver 115b across the medium transport path. The light emitter 115a is an LED or the like, and emits light toward the medium transport path. On the other hand, the light receiver 115b is a photodiode or the like, and receives the light emitted by the light emitter 115a and guided by the light guide tube. When a medium is present at a position facing at least one of the light emitter 115a and the light receiver 115b, the light emitted from the light emitter 115a is blocked by the medium, so that the light receiver 115b does not detect the light emitted from the light emitter 115a. The outside-area sensor 115 generates and outputs an outside-area signal whose signal value changes depending on whether a medium is present or not at the position of the outside-area sensor 115 based on the intensity of the light received by the light receiver 115b.

[0048] The light emitter 115a and the light receiver 115b are arranged side by side with a gap in the medium transport direction A1 so as to be arranged at the same position in the width direction A2. Note that the light emitter 115a and the light receiver 115b may be arranged side by side with a gap in the width direction A2 so as to be arranged at different positions in the width direction A2.

[0049] The second central sensor 116 is an example of a second sensor and a central sensor arranged downstream of the first sensor in the medium transport direction and at the center of the medium transport path in the direction perpendicular to the medium transport direction, and detects the medium transported to the arrangement position. The second central sensor 116 is arranged downstream of the feed roller 112 and the separation roller 113 in the medium transport direction A1, particularly downstream of the first central sensor 114, and at the center of the medium transport path in the width direction A2 perpendicular to the medium transport direction. That is, the second central sensor 116 is arranged at a different position from the first central sensor 114 in the medium transport direction A1. In particular, the second central sensor 116 is arranged downstream of the outside area sensor 115 and upstream of the imaging device 123 in the medium transport direction A1, particularly upstream of the nip portion N2 of the first transport roller 120 and the second transport roller 121. Further, the second central sensor 116 is disposed between the plurality of outside area sensors 115, between the plurality of first side sensors 117, between the second side sensors 119, and / or between the plurality of third side sensors 122 in the width direction A2. The second central sensor 116 is disposed between the plurality of feed rollers 112 (nip portion N1), between the plurality of first conveying rollers 120 (nip portion N2), and / or between the plurality of third conveying rollers 124 (nip portion N3) in the width direction A2. In the example shown in FIG. 3, the second central sensor 116 is disposed at the center position of the medium conveying path in the width direction A2.

[0050] The second central sensor 116 includes a light emitter 116a and a light receiver 116b provided on one side of the medium transport path, and a light guide tube provided at a position facing the light emitter 116a and the light receiver 116b across the medium transport path. The light emitter 116a is an LED or the like, and emits light toward the medium transport path. On the other hand, the light receiver 116b is a photodiode or the like, and receives the light emitted by the light emitter 116a and guided by the light guide tube. When a medium is present at a position facing at least one of the light emitter 116a and the light receiver 116b, the light emitted from the light emitter 116a is blocked by the medium, so that the light receiver 116b does not detect the light emitted from the light emitter 116a. The second central sensor 116 generates and outputs a second central signal whose signal value changes depending on whether a medium is present or not at the position of the second central sensor 116 based on the intensity of the light received by the light receiver 116b.

[0051] The light emitter 116a and the light receiver 116b are arranged side by side at intervals in the medium conveying direction A1 so that they are located at the same position in the width direction A2. This allows the medium conveying device 100 to more accurately detect the degree of inclination of the medium using the second central sensor 116 and the multiple first side sensors 117 or multiple second side sensors 119 arranged outside the second central sensor 116. Note that the light emitter 116a and the light receiver 116b may be arranged side by side at intervals in the width direction A2 so that they are located at different positions in the width direction A2.

[0052] The first side sensor 117 is an example of the third sensor, the fourth sensor, and the side sensor, which are respectively arranged downstream of the second sensor in the medium transport direction and on one side and the opposite side of the medium transport path in the direction perpendicular to the medium transport direction. The first side sensor 117 detects the medium transported to its arrangement position. In the example shown in FIG. 3, two first side sensors 117 are arranged side by side with an interval in the width direction A2. The first side sensor 117 is arranged downstream of the first center sensor 114 and the second center sensor 116 in the medium transport direction A1, and on both sides of the medium transport path in the width direction A2 perpendicular to the medium transport direction. In particular, the first side sensor 117 is arranged upstream of the imaging device 123 in the medium transport direction A1, and particularly upstream of the nip portion N2 of the first transport roller 120 and the second transport roller 121. The first side sensor 117 is disposed inward in the width direction A2 from the maximum size medium supported by the medium conveying device 100 when the medium is placed on the placement table 103, that is, inward from the position of the inner side surface of the side guide 103b when the medium is placed at the outermost position. The first side sensor 117 is disposed inward in the width direction A2 from the end position of the imaging range of the imaging device 123.

[0053] The first side sensor 117 includes a light emitter 117a and a light receiver 117b provided on one side of the medium transport path, and a light guide tube provided at a position facing the light emitter 117a and the light receiver 117b across the medium transport path. The light emitter 117a is an LED or the like, and emits light toward the medium transport path. On the other hand, the light receiver 117b is a photodiode or the like, and receives the light emitted by the light emitter 117a and guided by the light guide tube. When a medium is present at a position facing at least one of the light emitter 117a and the light receiver 117b, the light emitted from the light emitter 117a is blocked by the medium, so that the light receiver 117b does not detect the light emitted from the light emitter 117a. The first side sensor 117 generates and outputs a first side signal whose signal value changes depending on whether a medium is present or not at the position of the first side sensor 117 based on the intensity of the light received by the light receiver 117b.

[0054] The light emitter 117a and the light receiver 117b are arranged side by side at intervals in the width direction A2 so that they are arranged at different positions in the width direction A2. This allows the medium conveying device 100 to monitor the passage of the end of the conveyed medium in a wide area between the light emitter 117a and the light receiver 117b. Therefore, the medium conveying device 100 can more reliably detect the degree of inclination of the medium even if the placement position of the medium on the placement table 103 is misaligned. Note that the light emitter 117a and the light receiver 117b may be arranged side by side at intervals in the medium conveying direction A1 so that they are arranged at the same position in the width direction A2. In this case, the medium conveying device 100 can more accurately detect the degree of inclination of the medium.

[0055] The second side sensor 119 is an example of a fifth sensor and a side sensor arranged downstream of the third sensor in the medium transport direction and on one side of the medium transport path in the direction perpendicular to the medium transport direction. The second side sensor 119 detects the medium transported to its arrangement position. In the example shown in FIG. 3, two second side sensors 119 are arranged side by side with an interval in the width direction A2. The second side sensor 119 is arranged downstream of the first center sensor 114, the second center sensor 116, and the first side sensor 117 in the medium transport direction A1, and on both sides of the medium transport path in the width direction A2 perpendicular to the medium transport direction. That is, the second side sensor 119 is arranged at a different position from the first side sensor 117 in the medium transport direction A1. In particular, the second side sensor 119 is arranged upstream of the imaging device 123 in the medium transport direction A1, and particularly upstream of the nip portion N2 of the first transport roller 120 and the second transport roller 121. The second side sensor 119 is disposed inward in the width direction A2 from the maximum size medium supported by the medium conveying device 100 when placed on the placement table 103, that is, more inward from the position of the inner side surface of the side guide 103b when placed at the outermost position. The second side sensor 119 is disposed inward from the end position of the imaging range of the imaging device 123 in the width direction A2. Each second side sensor 119 is disposed inward (toward the center) from each first side sensor 117 in the width direction A2. Each second side sensor 119 may be disposed in the same position as each first side sensor 117 or outward from each first side sensor 117 in the width direction A2.

[0056] The second side sensor 119 includes a light emitter 119a and a light receiver 119b provided on one side of the medium transport path, and a light guide tube provided at a position facing the light emitter 119a and the light receiver 119b across the medium transport path. The light emitter 119a is an LED or the like, and emits light toward the medium transport path. On the other hand, the light receiver 119b is a photodiode or the like, and receives the light emitted by the light emitter 119a and guided by the light guide tube. When a medium is present at a position facing at least one of the light emitter 119a and the light receiver 119b, the light emitted from the light emitter 119a is blocked by the medium, so that the light receiver 119b does not detect the light emitted from the light emitter 119a. The second side sensor 119 generates and outputs a second side signal whose signal value changes depending on whether a medium is present or not at the position of the second side sensor 119 based on the intensity of the light received by the light receiver 119b.

[0057] The light emitter 119a and the light receiver 119b are arranged side by side at a distance in the width direction A2 so that they are arranged at different positions in the width direction A2. This allows the medium conveying device 100 to more reliably detect the degree of tilt of the medium. Note that the light emitter 119a and the light receiver 119b may also be arranged side by side at a distance in the medium conveying direction A1 so that they are arranged at the same position in the width direction A2. In that case, the medium conveying device 100 can more accurately detect the degree of tilt of the medium.

[0058] The third side sensor 122 detects the medium transported to its arrangement position. In the example shown in FIG. 3, two third side sensors 122 are arranged side by side with an interval in the width direction A2. The third side sensor 122 is arranged downstream of the first side sensor 117 and the second side sensor 119 in the medium transport direction A1, and on each of both sides of the medium transport path in the width direction A2 perpendicular to the medium transport direction. That is, the third side sensor 122 is arranged at a different position from each of the first side sensor 117 and the second side sensor 119 in the medium transport direction A1. In particular, the third side sensor 122 is arranged downstream of the nip portion N2 of the first transport roller 120 and the second transport roller 121 and upstream of the imaging device 123 in the medium transport direction A1. The third side sensor 122 is disposed inward in the width direction A2 from the maximum size medium supported by the medium conveying device 100 when the medium is placed on the placement table 103, that is, from the inner side surface of the side guide 103b when the medium is placed at the outermost position. The third side sensor 122 is disposed inward in the width direction A2 from the end position of the imaging range of the imaging device 123.

[0059] The third side sensor 122 includes a light emitter 122a and a light receiver 122b provided on one side of the medium transport path, and a light guide tube provided at a position facing the light emitter 122a and the light receiver 122b across the medium transport path. The light emitter 122a is an LED or the like, and emits light toward the medium transport path. On the other hand, the light receiver 122b is a photodiode or the like, and receives the light emitted by the light emitter 122a and guided by the light guide tube. When a medium is present at a position facing at least one of the light emitter 122a and the light receiver 122b, the light emitted from the light emitter 122a is blocked by the medium, so that the light receiver 122b does not detect the light emitted from the light emitter 122a. The third side sensor 122 generates and outputs a third side signal whose signal value changes depending on whether a medium is present or not at the position of the third side sensor 122 based on the intensity of the light received by the light receiver 122b.

[0060] The light emitter 122a and the light receiver 122b are arranged side by side at a distance in the width direction A2 so that they are located at different positions in the width direction A2. This allows the medium conveying device 100 to more reliably detect the degree of tilt of the medium. Note that the light emitter 122a and the light receiver 122b may also be arranged side by side at a distance in the medium conveying direction A1 so that they are located at the same position in the width direction A2. In that case, the medium conveying device 100 can more accurately detect the degree of tilt of the medium.

[0061] In addition, in each of the first central sensor 114, the outside area sensor 115, the second central sensor 116, the first side sensor 117, the second side sensor 119, and / or the third side sensor 122, a reflective member such as a mirror may be used instead of a light guide tube. In each sensor, the light emitter and the light receiver may be provided facing each other across the medium transport path. In addition, 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. In addition, each sensor may detect the presence of the medium using an ultrasonic sensor.

[0062] FIG. 4 is a block diagram showing a schematic configuration of the medium conveying device 100. As shown in FIG.

[0063] In addition to the components described above, the medium conveying device 100 further includes a motor 131, an interface device 132, a storage device 140, a processing circuit 150, and the like.

[0064] The motor 131 includes one or more motors, and rotates the feed roller 112, the separation roller 113, the first transport roller 120, the second transport roller 121, the third transport roller 124, and / or the fourth transport roller 125 to transport the medium in response to a control signal from the processing circuit 150. The motor 131 includes separate motors that independently rotate each of the feed rollers 112. The motor 131 may also include separate motors that independently rotate each of the first transport rollers 120, each of the second transport rollers 121, each of the third transport rollers 124, and each of the fourth transport rollers 125.

[0065] The interface device 132 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 mobile information terminal, etc.) to transmit and receive input images and various information. Also, instead of the interface device 132, a communication unit having an antenna for transmitting and receiving wireless signals and a wireless communication interface device for transmitting and receiving signals through a wireless communication line in accordance with a predetermined communication protocol may be used. The predetermined communication protocol is, for example, a wireless LAN (Local Area Network). The communication unit may have a wired communication interface device for transmitting and receiving signals through a wired communication line in accordance with a communication protocol such as a wired LAN.

[0066] The storage device 140 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 140 also stores computer programs, databases, tables, and the like used for various processes of the medium conveying device 100. The computer programs may be installed in the storage device 140 from a computer-readable portable recording medium using a known setup program or the like. The portable recording medium is, for example, a compact disc read only memory (CD-ROM), a digital versatile disc read only memory (DVD-ROM), or the like.

[0067] The storage device 140 stores, as data, an accumulated skew condition table, an abnormal skew condition table, and the like. The accumulated skew condition table stores accumulated skew conditions for determining whether an accumulated skew has occurred. The accumulated skew is an skew in which the tilt angle of the medium changes during transport, that is, the medium rotates and moves, among skews in which the medium is transported tilted. The abnormal skew condition table stores abnormal skew conditions for determining whether an abnormal skew has occurred. The abnormal skew is an skew in which the tilt angle of the medium does not change during transport, that is, the medium moves parallel while tilted, among skews in which the medium is transported tilted. In particular, the abnormal skew is an skew in which the medium may collide with a side wall of the medium transport path if the medium continues to move at that tilt angle. Skew in which the tilt angle of the medium does not change during transport is not limited to skew in which the tilt angle of the medium does not change at all during transport, but includes skew in which the tilt angle of the medium changes within a sufficiently small angle range (for example, 10 degrees or less) during transport. The cumulative skew condition table and the abnormal skew condition table will be described in detail later.

[0068] The processing circuit 150 operates based on a program previously stored in the storage device 140. The processing circuit is, for example, a CPU (Central Processing Unit). The processing circuit 150 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).

[0069] The processing circuit 150 is connected to the operation device 105, the display device 106, the placement sensor 111, the first central sensor 114, the outside area sensor 115, the second central sensor 116, the first side sensor 117, the thickness sensor 118, the second side sensor 119, the third side sensor 122, the imaging device 123, the motor 131, the interface device 132, the storage device 140, and the like, and controls each of these components. The processing circuit 150 performs drive control of the motor 131, imaging control of the imaging device 123, and the like, based on each signal received from each sensor, acquires an input image from the imaging device 123, and transmits it to the information processing device via the interface device 132. The processing circuit 150 also determines whether or not cumulative skew and / or abnormal skew of the medium has occurred, based on each signal received from each sensor.

[0070] FIG. 5 illustrates an example of a data structure of the cumulative skew condition table.

[0071] As shown in Fig. 5, the cumulative skew condition table stores cumulative skew conditions for determining that cumulative skew has occurred using first central sensor 114, second central sensor 116, first side sensor 117, and second side sensor 119. As the cumulative skew conditions, an order condition relating to the order of the sensors that detected the medium (the leading edge of the medium) and a time condition relating to the time from when the first sensor detects the medium to when a predetermined sensor detects the medium are set. In the example shown in Fig. 5, a plurality of cumulative skew conditions 1 to 7 are set in the cumulative skew condition table.

[0072] The order condition of cumulative skew condition 1 is set such that the first central sensor 114 detects the medium first, one of the multiple first side sensors 117 detects the medium second, and the second central sensor 116 detects the medium third. The time condition of cumulative skew condition 1 is set such that a first time from when the first central sensor 114 detects the medium to when the third central sensor 116 detects the medium is greater than a first threshold value T1. The first threshold value T1 is set in advance as a time between a first time when cumulative skew occurs and a first time when cumulative skew does not occur when the medium is transported to satisfy the order condition of cumulative skew condition 1.

[0073] Fig. 6(A) is a schematic diagram for explaining cumulative skew that satisfies cumulative skew conditions 1 to 4. Fig. 6(A) is a schematic diagram of lower housing 101 viewed from above with upper housing 102 open.

[0074] In FIG. 6A, lines L11 to L15 each show the transition of the leading edge of a medium where cumulative skew has occurred. Line L11 shows the leading edge of the medium when it passes the first central sensor 114. Line L12 shows the leading edge of the medium when it passes one of the multiple first side sensors 117. Line L13 shows the leading edge of the medium when it passes the second central sensor 116. Line L14 shows the leading edge of the medium when it passes one of the multiple second side sensors 119 that is arranged on the same side as the first side sensor 117 that the medium has passed through. Line L15 shows the leading edge of the medium when it passes the other sensor of the multiple first side sensors 117, that is, the sensor arranged on the opposite side of the first side sensor 117 that the medium has already passed through. In this way, when cumulative skew has occurred, it is highly likely that the leading edge of the medium will pass the position of the side sensor arranged downstream before the position of the central sensor arranged upstream, rather than passing through the positions of the sensors in order starting from the sensor arranged upstream.

[0075] Furthermore, when cumulative skew occurs, the angle of the leading edge of the medium with respect to the width direction A2 gradually increases. The cumulative skew occurs when a large amount of paper dust or the like adheres to only one of the multiple feed rollers 112, causing a difference in the magnitude of friction between each of the multiple feed rollers 112 and the medium, resulting in a difference in the feeding force applied to the medium from each feed roller 112. The cumulative skew also occurs when the leading medium is conveyed at an angle, causing the timing at which the rear end of the leading medium passes each feed roller 112 to differ, and the timing at which the feeding force begins to be applied to the trailing medium from each feed roller 112 to differ. In other words, when cumulative skew occurs, at least one of the multiple feed rollers 112 does not apply an appropriate feeding force to the medium. Therefore, the speed at which the medium advances in the medium conveying direction A1 when cumulative skew occurs is lower than the speed at which the medium advances in the medium conveying direction A1 when cumulative skew does not occur.

[0076] Therefore, medium conveying device 100 can appropriately determine whether cumulative skew has occurred based on the order in which the sensors detect the medium and the time intervals at which each sensor detects the medium.

[0077] Cumulative skew condition 1 specifies that the leading edge of the medium transitions along straight lines L11, L12, and L13 in that order, and that the time taken for the leading edge of the medium to pass the position of the first central sensor 114 as shown by straight line L11 and pass the position of the second central sensor 116 as shown by straight line L13 is long.

[0078] As an order condition of cumulative skew condition 2, in addition to the order condition of cumulative skew condition 1, it is set that the sensor arranged on the same side as the first side sensor 117 that detected the medium, among the multiple second side sensors 119, detects the medium fourth. As a time condition of cumulative skew condition 2, it is set that the second time from when the first central sensor 114 detects the medium to when the fourth second side sensor 119 detects the medium is greater than a second threshold value T2. The second threshold value T2 is set in advance as the time between the second time when cumulative skew occurs and the second time when cumulative skew does not occur when the medium is transported so as to satisfy the order condition of cumulative skew condition 2. In cumulative skew condition 2, it is stipulated that the leading edge of the medium transitions in the order of straight lines L11, L12, L13, and L14, and the time from when the leading edge of the medium passes the position of the first central sensor 114 as in straight line L11 to when the leading edge passes the position of the second side sensor 119 as in straight line L14 is large.

[0079] As the order condition of cumulative skew condition 3, in addition to the order condition of cumulative skew condition 2, it is set that the other sensor of the multiple first side sensors 117, i.e., the sensor arranged on the opposite side of the first side sensor 117 that has already detected the medium, detects the medium fifth. As the time condition of cumulative skew condition 3, it is set that a third time from when the first first central sensor 114 detects the medium to when the fifth first side sensor 117 detects the medium is greater than a third threshold value T3. The third threshold value T3 is preset as a time between a third time when cumulative skew occurs and a third time when cumulative skew does not occur when the medium is transported so as to satisfy the order condition of cumulative skew condition 3. In cumulative skew condition 3, it is stipulated that the leading edge of the medium transitions in the order of straight lines L11, L12, L13, L14, and L15, and the time from when the leading edge of the medium passes the position of the first central sensor 114 as in straight line L11 to when it passes the position of the first side sensor 117 as in straight line L15 is large.

[0080] As the order condition of cumulative skew condition 4, in addition to the order condition of cumulative skew condition 1, the other sensor of the multiple first side sensors 117, i.e., the sensor arranged on the opposite side of the first side sensor 117 that has already detected the medium, is set to detect the medium fourth. As the time condition of cumulative skew condition 4, a fourth time from when the first first central sensor 114 detects the medium to when the fourth first side sensor 117 detects the medium is set to be greater than a fourth threshold value T4. The fourth threshold value T4 is set in advance as a time between a fourth time when cumulative skew occurs and a fourth time when cumulative skew does not occur when the medium is transported so as to satisfy the order condition of cumulative skew condition 4. Depending on the transport status of the medium, there is a possibility that the leading edge of the medium will not pass a sensor of the multiple second side sensors 119 that is arranged on the same side as the first side sensor 117 that the medium passed through. Therefore, in cumulative skew condition 4, the sensor of the multiple second side sensors 119 that is arranged on the same side as the first side sensor 117 that detected the medium detects the medium fourth is excluded from cumulative skew condition 3.

[0081] The order condition of cumulative skew condition 5 is set such that first central sensor 114 detects the medium first, one of the multiple first side sensors 117 detects the medium second, and one of the multiple second side sensors 119 that is arranged on the same side as the first side sensor 117 that detected the medium detects the medium third. The time condition of cumulative skew condition 5 is set such that a fifth time from when the first first central sensor 114 detects the medium to when the third second side sensor 119 detects the medium is greater than a fifth threshold value T5. The fifth threshold value T5 is preset as a time between the fifth time when cumulative skew occurs and the fifth time when cumulative skew does not occur when the medium is transported to satisfy the order condition of cumulative skew condition 5.

[0082] Fig. 6(B) is a schematic diagram for explaining cumulative skew that satisfies cumulative skew conditions 5 to 7. Fig. 6(B) is a schematic diagram of lower housing 101 viewed from above with upper housing 102 open.

[0083] In FIG. 6B, lines L21 to L25 each show the transition of the leading edge of the medium where cumulative skew has occurred. Line L21 shows the leading edge of the medium when it passes the first central sensor 114. Line L22 shows the leading edge of the medium when it passes one of the multiple first side sensors 117. Line L23 shows the leading edge of the medium when it passes one of the multiple second side sensors 119 that is arranged on the same side as the first side sensor 117 that the medium has passed through. Line L24 shows the leading edge of the medium when it passes the second central sensor 116. Line L25 shows the leading edge of the medium when it passes the other sensor of the multiple first side sensors 117, that is, the sensor arranged on the opposite side of the first side sensor 117 that the medium has already passed through. In this way, when cumulative skew has occurred, the leading edge of the medium may pass the position of the second side sensor 119 before the position of the second central sensor 116.

[0084] Cumulative skew condition 5 specifies that the leading edge of the medium transitions in the order of straight lines L21, L22, and L23, and that the time taken for the leading edge of the medium to pass the position of the first central sensor 114 as shown by straight line L21 and pass the position of the second side sensor 119 as shown by straight line L23 is long.

[0085] As the order condition of cumulative skew condition 6, in addition to the order condition of cumulative skew condition 5, it is set that the second central sensor 116 detects the medium fourth. As the time condition of cumulative skew condition 6, it is set that the sixth time from when the first central sensor 114 detects the medium to when the fourth central sensor 116 detects the medium is greater than a sixth threshold value T6. The sixth threshold value T6 is preset as the time between the sixth time when cumulative skew occurs and the sixth time when cumulative skew does not occur when the medium is transported so as to satisfy the order condition of cumulative skew condition 6. Cumulative skew condition 6 specifies that the leading edge of the medium transitions in the order of straight lines L21, L22, L23, and L24, and that the time from when the leading edge of the medium passes the position of the first central sensor 114 as in straight line L21 to when the leading edge passes the position of the second central sensor 116 as in straight line L24 is large.

[0086] As the order condition of cumulative skew condition 7, in addition to the order condition of cumulative skew condition 6, the other sensor of the multiple first side sensors 117, i.e., the sensor arranged on the opposite side of the first side sensor 117 that has already detected the medium, is set to detect the medium fifth. As the time condition of cumulative skew condition 7, a seventh time from when the first first central sensor 114 detects the medium to when the fifth first side sensor 117 detects the medium is set to be greater than a seventh threshold value T7. The seventh threshold value T7 is preset as the time between the seventh time when cumulative skew occurs and the seventh time when cumulative skew does not occur when the medium is transported so as to satisfy the order condition of cumulative skew condition 7. In cumulative skew condition 7, it is stipulated that the leading edge of the medium transitions in the order of straight lines L21, L22, L23, L24, and L25, and the time from when the leading edge of the medium passes the position of the first central sensor 114 as in straight line L21 to when it passes the position of the first side sensor 117 as in straight line L25 is large.

[0087] It is sufficient that the cumulative skew condition table includes at least one of the cumulative skew conditions 1 to 7, and other conditions do not need to be set.

[0088] In the medium conveying device 100, the first center sensor 114 and the second center sensor 116 are disposed at mutually different positions in the medium conveying direction A1 in the center of the medium conveying path. Therefore, the first center sensor 114 is disposed at a position on the upstream side sufficiently distant from each side sensor disposed on the downstream side of the second center sensor 116. This makes the time from when the medium passes the position of the first center sensor 114 to when it passes the position of each side sensor sufficiently large, so that the medium conveying device 100 can detect the occurrence of cumulative skew with higher accuracy based on the time interval at which each sensor detects the medium. Furthermore, by providing the second center sensor 116 separately from the first center sensor 114, the medium conveying device 100 can set the cumulative skew conditions more precisely and detect the occurrence of cumulative skew with higher accuracy.

[0089] FIG. 7 is a diagram illustrating an example of a data structure of the abnormal skew condition table.

[0090] 7, the abnormal skew condition table stores abnormal skew conditions for determining that abnormal skew has occurred using first center sensor 114, second center sensor 116, first side sensor 117, and second side sensor 119. As the abnormal skew conditions, an order condition relating to the order of the sensors that detected the medium (the leading edge) and a time condition relating to the time from when the first sensor detects the medium to when a predetermined sensor detects the medium are set. In the example shown in FIG. 7, a plurality of abnormal skew conditions 1 to 4 are set in the abnormal skew condition table.

[0091] The order condition of abnormal skew condition 1 is set so that one of the multiple first side sensors 117 detects the medium first, and the first central sensor 114 detects the medium second. No time condition is set for abnormal skew condition 1. In other words, when the order condition of abnormal skew condition 1 is met, it is determined that abnormal skew condition 1 is met, regardless of the time from when a specific sensor detects the medium to when another sensor detects the medium.

[0092] Fig. 8(A) is a schematic diagram for explaining abnormal skew that satisfies abnormal skew conditions 1 and 2. Fig. 8(A) is a schematic diagram of lower housing 101 viewed from above with upper housing 102 open.

[0093] In FIG. 8A, lines L31 to L33 each show the transition of the leading edge of a medium in which abnormal skew has occurred. Line L31 shows the leading edge of the medium when it passes one of the multiple first side sensors 117. Line L32 shows the leading edge of the medium when it passes first central sensor 114. Line L33 shows the leading edge of the medium when it passes second central sensor 116. In this way, when abnormal skew has occurred, the leading edge of the medium is highly likely to tilt significantly and pass first side sensor 117, which is located on the downstream side, before passing the position of first central sensor 114, which is located in the center on the upstream side.

[0094] Furthermore, when abnormal skew occurs, in which the inclination angle of the medium does not change during transport, an appropriate feeding force is applied to the medium from both of the multiple feeding rollers 112. Therefore, the speed at which the medium advances in the medium transport direction A1 when abnormal skew occurs is higher than the speed at which the medium advances in the medium transport direction A1 when cumulative skew occurs.

[0095] Therefore, the media conveying device 100 can appropriately determine whether or not abnormal skew has occurred based on the order in which the sensors detect the media and the time between when the first sensor detects the media and when a particular sensor detects the media.

[0096] Abnormal skew condition 1 specifies that the leading edge of the medium transitions along straight lines L31 and L32 in that order.

[0097] The order condition for abnormal skew condition 2 is set such that one of the multiple first side sensors 117 detects the medium first, and the second central sensor 116 detects the medium second. No time condition is set for abnormal skew condition 2. Depending on the medium transport status, the leading edge of the medium may not pass the first central sensor 114. Therefore, abnormal skew condition 2 specifies that, unlike abnormal skew condition 1, the second central sensor 116 detects the medium second, not the first central sensor 114. Abnormal skew condition 2 specifies that the leading edge of the medium transitions in this order to lines L31 and L33, without passing through the state of line L32.

[0098] The order condition for abnormal skew condition 3 is set so that one of the multiple first side sensors 117 detects the medium first, then one of the multiple second side sensors 119 that is arranged on the same side as the first side sensor 117 that detected the medium detects the medium second, and then first central sensor 114 detects the medium third. No time condition is set for abnormal skew condition 3.

[0099] Fig. 8(B) is a schematic diagram for explaining abnormal skew that satisfies abnormal skew conditions 3 and 4. Fig. 8(B) is a schematic diagram of lower housing 101 viewed from above with upper housing 102 open.

[0100] In FIG. 8B, lines L41 to L44 each show the transition of the leading edge of a medium in which abnormal skew has occurred. Line L41 shows the leading edge of the medium when it passes one of the multiple first side sensors 117. Line L42 shows the leading edge of the medium when it passes one of the multiple second side sensors 119 that is arranged on the same side as the first side sensor 117 through which the medium has passed. Line L43 shows the leading edge of the medium when it passes the first central sensor 114. Line L44 shows the leading edge of the medium when it passes the second central sensor 116. In this way, when abnormal skew has occurred, the leading edge of the medium is greatly tilted, and there is a possibility that it passes the second side sensor 119 in addition to the first side sensor 117 arranged on the downstream side before passing the position of the first central sensor 114 arranged in the center on the upstream side.

[0101] Abnormal skew condition 3 specifies that the leading edge of the medium transitions along the straight lines L41, L42, and L43 in this order.

[0102] The order condition for abnormal skew condition 4 is set such that one of the multiple first side sensors 117 detects the medium first, a sensor of the multiple second side sensors 119 arranged on the same side as the first side sensor 117 that detected the medium detects the medium second, and the second central sensor 116 detects the medium third. No time condition is set for abnormal skew condition 4. Depending on the transport status of the medium, the leading edge of the medium may not pass the first central sensor 114. Therefore, abnormal skew condition 4 specifies that, compared to abnormal skew condition 3, the second central sensor 116 detects the medium third, not the first central sensor 114. Abnormal skew condition 4 specifies that the leading edge of the medium transitions from line L41 to line L42 to line L44, without passing through the state of line L43.

[0103] It is sufficient that the abnormal skew condition table includes at least one of the abnormal skew conditions 1 to 4, and other conditions do not need to be set.

[0104] In the medium conveying device 100, a first center sensor 114 and a second center sensor 116 are disposed at mutually different positions in the medium conveying direction A1 at the center of the medium conveying path. As a result, the first center sensor 114 is disposed at a position sufficiently distant upstream from each side sensor disposed downstream of the second center sensor 116. Therefore, when the medium passes the position of each side sensor before the position of the first center sensor 114, the medium conveying device 100 can determine that an abnormal skew, in which the angle of inclination of the medium is large, has occurred.

[0105] FIG. 9 is a diagram showing a schematic configuration of the storage device 140 and the processing circuit 150. As shown in FIG.

[0106] 9, the storage device 140 stores a control program 141, a determination program 142, and the like. Each of these programs is a functional module implemented by software that runs on a processor. The processing circuit 150 reads each program stored in the storage device 140 and operates according to the read program. In this way, the processing circuit 150 functions as a control unit 151 and a determination unit 152.

[0107] 10 and 11 are flowcharts showing an example of the operation of the medium reading process of the medium conveying device 100.

[0108] An example of the operation of the medium reading process of the medium conveying device 100 will be described below with reference to the flowcharts shown in Figures 10 and 11. Note that the flow of the operation described below is executed mainly by the processing circuit 150 in cooperation with each element of the medium conveying device 100 based on a program stored in advance in the storage device 140.

[0109] First, the control unit 151 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 132 (step S101).

[0110] Next, the control unit 151 acquires a placement signal from the placement sensor 111, and determines whether or not a medium is placed on the placement table 103 based on the acquired placement signal (step S102). If no medium is placed on the placement table 103, the control unit 151 ends the series of steps.

[0111] On the other hand, when a medium is placed on the placement table 103, the control unit 151 drives the motor 131. As a result, the control unit 151 rotates the feeding roller 112, the separation roller 113, the first conveying roller 120, the second conveying roller 121, the third conveying roller 124, and / or the fourth conveying roller 125 to feed and convey the medium (step S103).

[0112] Next, the determination unit 152 determines whether any of the cumulative skew conditions stored in the cumulative skew condition table is satisfied (step S104). The determination unit 152 periodically acquires a first central signal, a second central signal, a first side signal, and a second side signal from the first central sensor 114, the second central sensor 116, each of the first side sensors 117, and each of the second side sensors 119. When the signal value of each signal changes from a value indicating the absence of a medium to a value indicating the presence of a medium, the determination unit 152 determines that the leading edge of the medium has passed the position of the sensor that transmitted the signal. When the leading edge of the medium has passed the position of each sensor, the determination unit 152 stores the passing order and passing time of each sensor in the storage device 140. For each of the multiple cumulative skew conditions stored in the cumulative skew condition table, the determination unit 152 determines whether the passing order and passing time stored in the storage device 140 satisfy the order condition and time condition of each cumulative skew condition.

[0113] If none of the cumulative skew conditions is satisfied, the determining unit 152 determines that cumulative skew of the medium has not occurred (step S105), and the process proceeds to step S111.

[0114] On the other hand, if any of the cumulative skew conditions is satisfied, the determining unit 152 determines that cumulative skew of the medium has occurred (step S106).

[0115] In this way, the determination unit 152 determines whether a cumulative skew of the medium has occurred by determining whether each cumulative skew condition is satisfied. That is, the determination unit 152 determines whether the tilt angle of the medium during transport has changed based on which sensor detected the medium first, the sensor detected the medium second, and the sensor detected the medium third. Furthermore, the determination unit 152 determines whether the tilt angle of the medium during transport has changed based on the sum of the time intervals at which each sensor detects the medium, that is, at least the time from when the sensor that detected the medium first detected the medium to when the sensor that detected the medium third detected the medium.

[0116] In particular, the determination unit 152 determines whether cumulative skew of the medium has occurred by determining whether cumulative skew condition 1 is satisfied. That is, when the first central sensor 114 detects the medium first, one of the multiple first side sensors 117 detects the medium second, and the second central sensor 116 detects the medium third, the determination unit 152 determines whether the skew angle of the medium has changed during transport based on the first time from when the first central sensor 114 detects the medium to when the second central sensor 116 detects the medium.

[0117] Furthermore, the determination unit 152 determines whether cumulative skew of the medium has occurred by determining whether cumulative skew condition 3 or cumulative skew condition 4 is satisfied. That is, when the first central sensor 114 detects the medium first, one of the multiple first side sensors 117 detects the medium second, the second central sensor 116 detects the medium third, and then the other of the multiple first side sensors 117 detects the medium, the determination unit 152 determines whether the skew angle of the medium has changed during transport based on the third or fourth time from when the first central sensor 114 detects the medium to when the other of the multiple first side sensors 117 detects the medium.

[0118] Furthermore, the determination unit 152 determines whether cumulative skew of the medium has occurred by determining whether cumulative skew condition 5 is satisfied. That is, when the first central sensor 114 detects the medium first, one of the multiple first side sensors 117 detects the medium second, and a sensor of the multiple second side sensors 119 that is arranged on the same side as the first side sensor 117 that detected the medium second detects the medium third, the determination unit 152 determines whether the skew angle of the medium has changed during transport based on a fifth time from when the first central sensor 114 detects the medium to when the second side sensor 119 detects the medium.

[0119] This enables the determination unit 152 to detect a change in the tilt angle of the medium being transported early and with high accuracy.

[0120] Next, the determination unit 152 determines whether the outside-area sensor 115 has detected the end of the side where the medium's progress is delayed (step S107). The determination unit 152 periodically receives outside-area signals from the multiple outside-area sensors 115. When the signal value of any of the outside-area signals received from the outside-area sensor 115 arranged on the opposite side of the first side sensor 117 that first detected the medium indicates the presence of the medium, the determination unit 152 determines that the end of the medium has passed the position of that outside-area sensor 115. In that case, the determination unit 152 determines that the outside-area sensor 115 has detected the end of the side where the medium's progress is delayed.

[0121] If the outside-area sensor 115 detects the edge on the side where the progress of the medium is delayed, the determination unit 152 does not execute skew correction of the medium (step S108), and moves the process to step S111.

[0122] 12(A) and (B) are schematic diagrams showing a state in which the edge of the medium passes the position of the outside-of-area sensor 115. Figures 12(A) and (B) are schematic diagrams of the lower housing 101 as viewed from above with the upper housing 102 open.

[0123] The dotted line in Fig. 12(A) shows medium M1 being transported at an incline so that the right portion of the leading edge is leading, and the right end passes the right outside-area sensor 115. In order to correct the incline of medium M1, it is necessary to make the peripheral speed of the feed roller 112 arranged on the lagging side higher than the peripheral speed of the feed roller 112 arranged on the leading side, so that the lagging side (left side) of the medium advances more than the leading side (right side). In this case, medium M1 rotates in the direction of arrow A11 in Fig. 12(A), as shown by the dashed line, and the right end of medium M1 moves (rotates) in a direction away from the right side wall of the medium transport path.

[0124] The dotted line in FIG. 12B indicates medium M2 that is transported at an incline so that the left portion of the leading edge is ahead, and the right end passes the right outside area sensor 115. In order to correct the incline of medium M2, it is necessary to make the circumferential speed of the feed roller 112 arranged on the lagging side higher than the circumferential speed of the feed roller 112 arranged on the leading side so that the lagging side (right side) of the medium advances further than the leading side (left side). In this case, medium M2 rotates in the direction of arrow A12 in FIG. 12B, as shown by the dashed line, and the right end of medium M2 moves (rotates) in a direction approaching the right side wall of the medium transport path. As a result, the right end of medium M2 may collide with the right side wall of the medium transport path, causing a medium jam.

[0125] In this way, if medium skew correction is performed when the outside-area sensor 115 detects the end of the medium on the side where the medium progress is delayed, the end of the medium on the side where the medium progress is delayed may collide with the side wall of the medium, causing a medium jam. By not performing medium skew correction when the outside-area sensor 115 detects the end of the medium on the side where the medium progress is delayed, the determination unit 152 can suppress the occurrence of a medium jam.

[0126] On the other hand, when the outside area sensor 115 does not detect the edge of the medium on the side where the medium is moving slowly, the determination unit 152 calculates the first skew amount of the medium (step S109). The determination unit 152 calculates the time from when the first side sensor 117 arranged on the leading side detects the leading edge of the medium to when the first side sensor 117 arranged on the side where the medium is moving slowly detects the leading edge of the medium as the first skew amount. The determination unit 152 may calculate the distance obtained by multiplying the above-mentioned time by the transport speed of the medium as the first skew amount. The determination unit 152 may also calculate the division value obtained by dividing the above-mentioned distance by the distance between the multiple first side sensors 117, or the arc tangent of the division value as the first skew amount. The determination unit 152 may also calculate the first skew amount using the timing when each second side sensor 119 detects the medium instead of the timing when each first side sensor 117 detects the medium.

[0127] Next, the control unit 151 starts skew correction of the medium (step S110). The control unit 151 corrects the skew of the medium by making the circumferential velocities of the multiple feed rollers 112 different from each other. The control unit 151 changes the circumferential speed of each feed roller 112 so that the circumferential speed of the feed roller 112 arranged on the side where the progress of the medium is delayed in the width direction A2 is faster (higher) than the circumferential speed of the feed roller 112 arranged on the leading side. The control unit 151 increases (increases) the circumferential speed of the feed roller 112 arranged on the side where the progress of the medium is delayed, and / or decreases (decreases) the circumferential speed of the feed roller 112 arranged on the leading side. The control unit 151 sets each circumferential speed so that the difference between the circumferential speed of the feed roller 112 arranged on the side where the progress of the medium is delayed and the circumferential speed of the feed roller 112 arranged on the leading side increases as the first skew amount increases. As a result, the medium rotates about the feed roller 112 arranged on the leading side, eliminating skew in the medium.

[0128] Next, the determination unit 152 determines whether or not any of the abnormal skew conditions stored in the abnormal skew condition table is satisfied (step S111). For each of the abnormal skew conditions stored in the abnormal skew condition table, the determination unit 152 determines whether or not the passing order and passing time stored in the storage device 140 satisfy the order condition and time condition of each abnormal skew condition.

[0129] If any of the abnormal skew conditions is satisfied, the determining unit 152 determines that an abnormal skew of the medium has occurred (step S112).

[0130] Next, the control unit 151 executes abnormality processing of the medium (step S113), and ends the series of steps. As abnormality processing, the control unit 151 stops the motor 131 to stop feeding and transporting the medium. Also, as abnormality processing, the control unit 151 notifies the user by displaying information indicating that abnormal skew of the medium has occurred on the display device 106 or transmitting the information to the information processing device via the interface device 132.

[0131] On the other hand, if none of the abnormal skew conditions is satisfied in step S111, the determining unit 152 determines that abnormal skew of the medium has not occurred (step S114).

[0132] In this way, the determination unit 152 determines whether abnormal skew of the medium has occurred by determining whether abnormal skew condition 1 is satisfied. That is, if one of the first side sensors 117 detects the medium before the first central sensor 114 detects the medium, the determination unit 152 determines that skew has occurred without changing the tilt angle of the medium during transport.

[0133] The determination unit 152 also determines whether abnormal skew of the medium has occurred by determining whether abnormal skew condition 3 is satisfied. That is, if one of the second side sensors 119 detects the medium before the first central sensor 114 detects the medium, the determination unit 152 determines that skew has occurred without changing the tilt angle of the medium during transport.

[0134] These enable the determination unit 152 to detect early and with high accuracy whether the medium being transported is being transported so as to collide with a side wall of the transport path.

[0135] Next, the determination unit 152 determines whether the leading edge of the medium has passed the positions of the first conveyor roller 120 and the second conveyor roller 121 (step S115). The determination unit 152 periodically acquires a third side signal from each third side sensor 122. The determination unit 152 determines that the leading edge of the medium has passed the positions of the first conveyor roller 120 and the second conveyor roller 121 when the signal value of any of the third side signals changes from a value indicating that the medium is not present to a value indicating that the medium is present. The determination unit 152 may determine that the leading edge of the medium has passed the positions of the first conveyor roller 120 and the second conveyor roller 121 when a predetermined time has elapsed since the start of feeding the medium. If the leading edge of the medium has not yet passed the positions of the first conveyor roller 120 and the second conveyor roller 121, the determination unit 152 returns to the process of step S104 and repeats the processes from step S104 onward.

[0136] On the other hand, when the leading edge of the medium passes through the positions of the first conveyor roller 120 and the second conveyor roller 121, the control unit 151 causes the imaging device 123 to start capturing an image of the medium (step S116).

[0137] Next, the determination unit 152 determines whether or not skew correction is currently being performed (step S117). The determination unit 152 determines whether or not skew correction is currently being performed depending on whether or not the control unit 151 has started skew correction in step S110. If skew correction is not currently being performed, the determination unit 152 proceeds to step S122.

[0138] On the other hand, if skew correction is being performed, the determination unit 152 calculates a second skew amount of the medium (step S118). The determination unit 152 calculates, as the second skew amount, the time from when the third side sensor 122 arranged on the leading side detects the leading edge of the medium to when the third side sensor 122 arranged on the delayed side detects the leading edge of the medium.

[0139] The determination unit 152 may calculate, as the second skew amount, a time from when the first side sensor 117 arranged on the leading side detects the rear end of the medium until the first side sensor 117 arranged on the side where the medium is lagging detects the rear end of the medium. The determination unit 152 may calculate, as the second skew amount, a time from when the third side sensor 122 arranged on the leading side detects the rear end of the medium until the third side sensor 122 arranged on the side where the medium is lagging detects the rear end of the medium. The determination unit 152 may calculate, as the second skew amount, a distance obtained by multiplying each of the above times by the transport speed of the medium. The determination unit 152 may calculate, as the second skew amount, a divided value obtained by dividing the above distance by the distance between the multiple third side sensors 122, or an arctangent of the divided value.

[0140] Next, the determination unit 152 determines whether the amount of change between the first skew amount calculated in step S109 and the second skew amount calculated in step S118 is equal to or greater than the change amount threshold (step S119). The determination unit 152 calculates the amount of change as a subtraction value obtained by subtracting the second skew amount from the first skew amount, or a division value obtained by dividing the first skew amount by the second skew amount. If the amount of change is equal to or greater than the change amount threshold, the determination unit 152 determines that the amount of skew correction is appropriate, and proceeds to step S122 without changing the amount of skew correction. On the other hand, if the amount of change is less than the change amount threshold, the determination unit 152 determines that the amount of skew correction is insufficient. The change amount threshold is set to a value between the amount of change when the skew of the medium is appropriately corrected and the amount of change when the skew of the medium is not appropriately corrected, based on a previous experiment.

[0141] If the amount of change is less than the change amount threshold, the determination unit 152 determines whether the thickness of the medium being transported is equal to or greater than the thickness threshold (step S120). The determination unit 152 periodically acquires a thickness signal from the thickness sensor 118. If the thickness sensor 118 is an ultrasonic sensor, the determination unit 152 determines that the thickness of the medium is equal to or greater than the thickness threshold when the signal value of any of the thickness signals is equal to or less than a predetermined threshold. The thickness threshold is set to a value between the thickness of PPC (Plain Paper Copier) paper and the thickness of thin paper, for example. The predetermined threshold is set to a signal value of the thickness signal when the thickness of the medium being transported is equal to the thickness threshold. If the thickness sensor 118 is a reflected light sensor, a pressure sensor, or a movement amount sensor, the determination unit 152 determines that the thickness of the medium is equal to or greater than the thickness threshold when the signal value of any of the thickness signals is equal to or greater than the predetermined threshold. If the thickness of the medium is less than the thickness threshold, the determination unit 152 determines that the medium being transported is thin paper, and proceeds to step S122 without changing the skew correction amount. This allows the medium conveying device 100 to prevent a weak medium, such as thin paper, from being damaged by forcibly rotating the medium. On the other hand, when the thickness of the medium is equal to or greater than the thickness threshold, the determination unit 152 determines that the conveyed medium is not thin paper.

[0142] If the thickness of the medium is equal to or greater than the thickness threshold, the control unit 151 changes the amount of skew correction (step S121). The control unit 151 increases the amount of skew correction from the current amount of skew correction. The control unit 151 sets the circumferential speeds of the feed rollers 112 arranged on the side where the progress of the medium is delayed and the feed rollers 112 arranged on the side where the progress of the medium is advanced so that the difference between the circumferential speeds is greater than the difference set in step S110. When the initially set amount of skew correction is not sufficient to correct the skew of the medium, the control unit 151 increases the amount of skew correction to more reliably correct the skew of the medium. This allows the control unit 151 to prevent the medium from being captured in an inclined state, resulting in image loss in which a part (corner) of the medium is not included in the input image. Furthermore, the control unit 151 changes the amount of skew correction in stages to prevent the medium from being jammed or damaged due to overcorrection of the skew, and to prevent the transport speed of the medium from decreasing.

[0143] Next, the control unit 151 waits until the rear end of the medium passes the imaging position of the imaging device 123 (step S122). The control unit 151 periodically acquires a third side signal from each third side sensor 122. The control unit 151 determines that the rear end of the medium has passed the position of each third side sensor 122 when the signal value of each third side signal changes from a value indicating the presence of the medium to a value indicating the absence of the medium. The control unit 151 determines that the rear end of the medium has passed the imaging position when a predetermined time has elapsed since the rear end of the medium passed the position of any one of the third side sensors 122. The predetermined time is set to the time required for the medium to move from the position of the third side sensor 122 to the imaging position of the imaging device 123. Note that the control unit 151 may determine that the rear end of the medium has passed the imaging position when a predetermined time has elapsed since the start of feeding the medium.

[0144] Next, the control unit 151 acquires an input image from the imaging device 123, and outputs the acquired input image by transmitting it to the information processing device via the interface device 132 (step S123).

[0145] Next, control unit 151 determines whether or not a medium remains on placement table 103 based on the placement signal obtained from placement sensor 111 (step S124). If a medium remains on placement table 103, control unit 151 returns the process to step S103, and repeats the processes of steps S103 to S124.

[0146] On the other hand, if no media remain on the placement table 103, the control unit 151 stops the motor 131. As a result, the control unit 151 stops the feed roller 112, the separation roller 113, the first conveyor roller 120, the second conveyor roller 121, the third conveyor roller 124, and / or the fourth conveyor roller 125 (step S125). Then, the control unit 151 ends the series of steps.

[0147] The processes of steps S104 to S110 may be omitted, and the determination unit 152 may not determine whether or not a cumulative skew of the medium has occurred. The processes of steps S107 to S108 may be omitted, and the control unit 151 may execute skew correction of the medium regardless of whether or not the outside-area sensor 115 detects the end of the side where the progress of the medium is delayed. The processes of steps S111 to S114 may be omitted, and the determination unit 152 may not determine whether or not an abnormal skew of the medium has occurred. The processes of steps S117 to S121 may be omitted, and the control unit 151 may not change the amount of skew correction. The process of step S119 may be omitted, and the control unit 151 may change the amount of skew correction of the medium regardless of whether or not the amount of change is equal to or greater than the change amount threshold. The process of step S120 may be omitted, and the control unit 151 may change the amount of skew correction of the medium regardless of whether or not the thickness of the medium is equal to or greater than the thickness threshold.

[0148] Furthermore, the control unit 151 may accept a setting by the user using the operation device 105 or the information processing device as to whether or not to execute each process of steps S104 to S110, S107 to S108, S111 to S114, S117 to S121, S119, or S120.

[0149] Furthermore, if the first skew amount calculated in step S109 is greater than the skew amount threshold, the control unit 151 may execute abnormality processing without executing skew correction of the medium, and end the series of steps. The skew amount threshold is set to, for example, the average, median, or minimum value of the first skew amount when the medium collides with a side wall of the medium transport path when the medium transport is continued in a previous experiment. This allows the medium transport device 100 to prevent the medium from being damaged by forcibly rotating the medium too much.

[0150] As described above in detail, in the medium conveying device 100, one or more sensors are disposed in the center and / or on the side of the medium conveying path. The medium conveying device 100 determines whether or not the tilt angle of the medium being conveyed has changed based on the time from when one sensor detects the medium to when another sensor detects the medium. This enables the medium conveying device 100 to appropriately determine whether or not the tilt angle of the medium being conveyed has changed.

[0151] In particular, the medium conveying device 100 is capable of detecting the occurrence of cumulative skew in the medium at an early stage and appropriately correcting the cumulative skew in the medium, thereby improving the processing performance of the medium reading process.

[0152] Furthermore, medium conveying device 100 can stably convey media regardless of how the user sets the media on mounting table 103, thereby improving the productivity of input images. When setting media on mounting table 103, the user no longer needs to align the leading ends of the media or align the ends of media of different sizes, and medium conveying device 100 can improve user convenience.

[0153] 13A and 13B are diagrams showing an example of the data structure of an accumulated skew condition table and an abnormal skew condition table in a medium conveying device according to another embodiment.

[0154] In the cumulative skew condition table according to this embodiment, cumulative skew conditions 8 to 9 shown in Fig. 13(A) are set in addition to cumulative skew conditions 1 to 7 shown in Fig. 5. Moreover, in the abnormal skew condition table, abnormal skew conditions 1 to 2 shown in Fig. 13(B) are set instead of abnormal skew conditions 1 to 4 shown in Fig. 7.

[0155] The order condition of cumulative skew condition 8 is set such that one of the multiple first side sensors 117 detects the medium first, the first central sensor 114 detects the medium second, the sensor of the multiple second side sensors 119 that is arranged on the same side as the first side sensor 117 that detected the medium detects the medium third, and the second central sensor 116 detects the medium fourth. The time condition of cumulative skew condition 8 is set such that the eighth time from when the first first side sensor 117 detects the medium to when the fourth second central sensor 116 detects the medium is greater than an eighth threshold value T8. The eighth threshold value T8 is preset to a time between the eighth time when cumulative skew occurs and the eighth time when abnormal skew occurs when the medium is transported to satisfy the order condition of cumulative skew condition 8.

[0156] On the other hand, the order condition of abnormal skew condition 1 is set to the same condition as the order condition of cumulative skew condition 8. However, the time condition of abnormal skew condition 1 is set to be that the eighth time from when the first side sensor 117 detects the medium to when the fourth second central sensor 116 detects the medium is equal to or less than an eighth threshold value T8.

[0157] Fig. 14(A) is a schematic diagram for explaining cumulative skew that satisfies cumulative skew condition 8, and Fig. 14(B) is a schematic diagram for explaining abnormal skew that satisfies abnormal skew condition 1. Figs. 14(A) and (B) are schematic diagrams of lower housing 101 viewed from above with upper housing 102 open.

[0158] In Fig. 14(A), lines L51 to L54 each show the transition of the leading edge of a medium where cumulative skew has occurred. Line L51 shows the leading edge of the medium when it passes one of the multiple first side sensors 117. Line L52 shows the leading edge of the medium when it passes first central sensor 114. Line L53 shows the leading edge of the medium when it passes one of the multiple second side sensors 119 that is arranged on the same side as the first side sensor 117 that the medium passed. Line L14 shows the leading edge of the medium when it passes second central sensor 116.

[0159] 14(B), lines L61 to L64 each show the transition of the leading edge of a medium in which abnormal skew has occurred. Line L61 shows the leading edge of the medium when it passes one of the multiple first side sensors 117. Line L62 shows the leading edge of the medium when it passes first central sensor 114. Line L63 shows the leading edge of the medium when it passes one of the multiple second side sensors 119 that is located on the same side as the first side sensor 117 that the medium passed. Line L64 shows the leading edge of the medium when it passes second central sensor 116.

[0160] In this way, the order of the sensors that detect the medium may be the same when cumulative skew occurs and when abnormal skew occurs. However, as described above, the speed at which the medium advances in the medium conveying direction A1 when abnormal skew occurs is higher than the speed at which the medium advances in the medium conveying direction A1 when cumulative skew occurs. Therefore, the medium conveying device 100 can appropriately determine whether cumulative skew or abnormal skew has occurred based on the time interval at which each sensor detects the medium.

[0161] Accumulative skew condition 8 specifies that the leading edge of the medium transitions in the order of straight lines L51, L52, L53, and L54, and that the time from when the leading edge of the medium passes the position of the first side sensor 117 as shown by straight line L51 to when it passes the position of the second central sensor 116 as shown by straight line L54 is large. Abnormal skew condition 1 specifies that the leading edge of the medium transitions in the order of straight lines L61, L62, L63, and L64, and that the time from when the leading edge of the medium passes the position of the first side sensor 117 as shown by straight line L61 to when it passes the position of the second central sensor 116 as shown by straight line L64 is short.

[0162] 13A and 13B, the order condition of cumulative skew condition 9 is set such that one of the multiple first side sensors 117 detects the medium first, the sensor of the multiple second side sensors 119 that is arranged on the same side as the first side sensor 117 that detected the medium detects the medium second, the first central sensor 114 detects the medium third, and the second central sensor 116 detects the medium fourth. The time condition of cumulative skew condition 9 is set such that the ninth time from when the first first side sensor 117 detects the medium to when the fourth second central sensor 116 detects the medium is greater than a ninth threshold T9. The ninth threshold T9 is preset to the time between the ninth time when cumulative skew occurs and the ninth time when abnormal skew occurs when the medium is transported to satisfy the order condition of cumulative skew condition 9.

[0163] On the other hand, the order condition of abnormal skew condition 2 is set to the same condition as the order condition of cumulative skew condition 9. However, the time condition of abnormal skew condition 2 is set to be that the ninth time from when the first side sensor 117, which is the first sensor, detects the medium to when the fourth central sensor 116, which is the fourth sensor, detects the medium is equal to or less than a ninth threshold value T9.

[0164] Fig. 15(A) is a schematic diagram for explaining cumulative skew that satisfies cumulative skew condition 9, and Fig. 15(B) is a schematic diagram for explaining abnormal skew that satisfies abnormal skew condition 2. Figs. 15(A) and (B) are schematic diagrams of lower housing 101 viewed from above with upper housing 102 open.

[0165] In Fig. 15(A), lines L71 to L74 each show the transition of the leading edge of a medium where cumulative skew has occurred. Line L71 shows the leading edge of the medium when it passes one of the multiple first side sensors 117. Line L72 shows the leading edge of the medium when it passes one of the multiple second side sensors 119 that is arranged on the same side as the first side sensor 117 that the medium passed. Line L73 shows the leading edge of the medium when it passes the first central sensor 114. Line L74 shows the leading edge of the medium when it passes the second central sensor 116.

[0166] 15(B), lines L81 to L84 each show the transition of the leading edge of a medium in which abnormal skew has occurred. Line L81 shows the leading edge of the medium when it passes one of the multiple first side sensors 117. Line L82 shows the leading edge of the medium when it passes one of the multiple second side sensors 119 that is arranged on the same side as the first side sensor 117 that the medium passed. Line L83 shows the leading edge of the medium when it passes the first central sensor 114. Line L84 shows the leading edge of the medium when it passes the second central sensor 116.

[0167] In this way, the order of the sensors that detect the medium may be the same when cumulative skew occurs and when abnormal skew occurs. However, as described above, the speed at which the medium advances in the medium conveying direction A1 when abnormal skew occurs is higher than the speed at which the medium advances in the medium conveying direction A1 when cumulative skew occurs. Therefore, the medium conveying device 100 can appropriately determine whether cumulative skew or abnormal skew has occurred based on the time interval at which each sensor detects the medium.

[0168] Accumulative skew condition 9 specifies that the leading edge of the medium transitions in the order of straight lines L71, L72, L73, and L74, and that the time from when the leading edge of the medium passes the position of the first side sensor 117 as shown by straight line L71 to when it passes the position of the second central sensor 116 as shown by straight line L74 is large. Abnormal skew condition 1 specifies that the leading edge of the medium transitions in the order of straight lines L81, L82, L83, and L84, and that the time from when the leading edge of the medium passes the position of the first side sensor 117 as shown by straight line L81 to when it passes the position of the second central sensor 116 as shown by straight line L84 is short.

[0169] As described above in detail, the media conveying device is now able to appropriately determine whether the tilt angle of the media is changing during transport, even when determining whether cumulative skew or abnormal skew is occurring based on the time interval at which each sensor detects the media.

[0170] 16A and 16B are diagrams showing an example of the data structures of an accumulated skew condition table and an abnormal skew condition table in a medium conveying device according to still another embodiment.

[0171] The medium conveying device according to this embodiment has the same configuration and function as the medium conveying device 100. However, in this embodiment, the medium conveying device does not have the second center sensor 116, and the only sensor arranged in the center of the medium conveying path in the width direction A2 is the first center sensor 114. In this embodiment, the first center sensor 114 is an example of a first sensor and a center sensor arranged in the center of the medium conveying path in a direction perpendicular to the medium conveying direction. In addition, the first side sensor 117 is an example of a second sensor and a fourth sensor arranged downstream of the first sensor in the medium conveying direction and on one side and the opposite side of the medium conveying path in a direction perpendicular to the medium conveying direction. In addition, the second side sensor 119 is an example of a third sensor arranged downstream of the second sensor in the medium conveying direction and on one side of the medium conveying path in a direction perpendicular to the medium conveying direction. In addition, the first side sensor 117 and the second side sensor 119 are examples of side sensors.

[0172] The cumulative skew condition table stores cumulative skew conditions for determining that a cumulative skew has occurred using the first central sensor 114, the first side sensor 117, and the second side sensor 119. Also, the abnormal skew condition table stores abnormal skew conditions for determining that an abnormal skew has occurred using the first central sensor 114, the first side sensor 117, and the second side sensor 119.

[0173] The order condition of cumulative skew condition 1 is set such that the first central sensor 114 detects the medium first, one of the multiple first side sensors 117 detects the medium second, and one of the multiple second side sensors 119 that is arranged on the same side as the first side sensor 117 that detected the medium detects the medium third. That is, the order condition of cumulative skew condition 1 is set such that the condition of cumulative skew condition 2 shown in FIG. 5 is deleted from the condition of second central sensor 116 detecting the medium third. The time condition of cumulative skew condition 1 is set such that the 10th time from when the first first central sensor 114 detects the medium to when the third second side sensor 119 detects the medium is greater than a 10th threshold T10. The 10th threshold T10 is preset to the time between the 10th time when cumulative skew occurs and the 10th time when cumulative skew does not occur when the medium is transported to satisfy the order condition of cumulative skew condition 1.

[0174] As the order condition of cumulative skew condition 2, in addition to the order condition of cumulative skew condition 1, the other sensor of the multiple first side sensors 117, i.e., the sensor arranged on the opposite side of the first side sensor 117 that has already detected the medium, is set to detect the medium fourth. That is, as the order condition of cumulative skew condition 1, a condition is set from cumulative skew condition 3 shown in FIG. 5 in which the second central sensor 116 detects the medium third, is deleted. As the time condition of cumulative skew condition 2, it is set that an eleventh time from when the first first central sensor 114 detects the medium to when the fourth first side sensor 117 detects the medium is greater than an eleventh threshold value T11. The eleventh threshold value T11 is preset to a time between an eleventh time when cumulative skew occurs and an eleventh time when cumulative skew does not occur when the medium is transported to satisfy the order condition of cumulative skew condition 2.

[0175] The order condition of cumulative skew condition 3 is set such that one of the multiple first side sensors 117 detects the medium first, the first central sensor 114 detects the medium second, and the multiple second side sensors 119, which is arranged on the same side as the first side sensor 117 that detected the medium, detects the medium third. That is, the order condition of cumulative skew condition 3 is set such that the first central sensor 114 detects the medium first from cumulative skew condition 2 shown in FIG. 5 is deleted, and the first central sensor 114 detects the medium third instead of the second central sensor 116. The time condition of cumulative skew condition 3 is set such that the 12th time from when the first first side sensor 117 detects the medium to when the third second side sensor 119 detects the medium is greater than a 12th threshold T12. The 12th threshold T12 is preset to the time between the 12th time when cumulative skew occurs and the 12th time when cumulative skew does not occur when the medium is transported to satisfy the order condition of cumulative skew condition 3.

[0176] As the order condition of cumulative skew condition 4, in addition to the order condition of cumulative skew condition 3, the other sensor of the multiple first side sensors 117, i.e., the sensor arranged on the opposite side of the first side sensor 117 that has already detected the medium, is set to detect the medium fourth. That is, as the order condition of cumulative skew condition 4, the condition of the first central sensor 114 detecting the medium first is deleted from the cumulative skew condition 3 shown in FIG. 5, and the first central sensor 114 detects the medium third instead of the second central sensor 116 is set. As the time condition of cumulative skew condition 4, a thirteenth time from when the first first side sensor 117 detects the medium to when the fourth first side sensor 117 detects the medium is set to be greater than a thirteenth threshold T13. The thirteenth threshold T13 is preset to the time between the thirteenth time when cumulative skew occurs and the thirteenth time when cumulative skew does not occur when the medium is transported so as to satisfy the order condition of cumulative skew condition 4.

[0177] On the other hand, the abnormal skew condition 1 may be set to the same condition as the abnormal skew condition 1 shown in FIG. 7, and the abnormal skew condition 2 may be set to the same condition as the abnormal skew condition 3 shown in FIG.

[0178] In this embodiment, the determination unit 152 also determines whether a cumulative skew of the medium has occurred by determining whether each cumulative skew condition is satisfied. That is, the determination unit 152 determines whether the tilt angle of the medium during transport has changed based on which sensor detected the medium first, the sensor detected the medium second, and the sensor detected the medium third. Furthermore, the determination unit 152 determines whether the tilt angle of the medium during transport has changed based on the sum of the time intervals at which each sensor detects the medium, that is, at least the time from when the sensor that detected the medium first detected the medium to when the sensor that detected the medium third detected the medium.

[0179] In particular, determination unit 152 determines whether cumulative skew of the medium has occurred by determining whether cumulative skew condition 1 is satisfied. That is, when first central sensor 114 detects the medium first, one of the multiple first side sensors 117 detects the medium second, and a sensor of the multiple second side sensors 119 that is arranged on the same side as first side sensor 117 that detected the medium second detects the medium third, determination unit 152 determines whether the skew angle of the medium has changed during transport based on the 10th time from when first central sensor 114 detects the medium to when second side sensor 119 detects the medium.

[0180] Furthermore, determination unit 152 determines whether cumulative skew of the medium has occurred by determining whether cumulative skew condition 3 is satisfied. That is, when one of the multiple first side sensors 117 detects the medium first, first central sensor 114 detects the medium second, and a sensor of the multiple second side sensors 119 that is arranged on the same side as first side sensor 117 that detected the medium first detects the medium third, determination unit 152 determines whether the skew angle of the medium has changed during transport based on the 12th time from when first side sensor 117 detects the medium to when second side sensor 119 detects the medium.

[0181] Furthermore, the determination unit 152 determines whether cumulative skew of the medium has occurred by determining whether cumulative skew condition 2 is satisfied. That is, when the first central sensor 114 detects the medium first, one of the multiple first side sensors 117 detects the medium second, a sensor of the multiple second side sensors 119 arranged on the same side as the first side sensor 117 that detected the medium second detects the medium third, and then the other sensor of the multiple first side sensors 117 detects the medium, the determination unit 152 determines whether the skew angle of the medium has changed during transport based on an eleventh time from when the first central sensor 114 detects the medium to when the other sensor of the multiple first side sensors 117 detects the medium.

[0182] Furthermore, the determination unit 152 determines whether cumulative skew of the medium has occurred by determining whether cumulative skew condition 4 is satisfied. That is, when one of the multiple first side sensors 117 detects the medium first, the first central sensor 114 detects the medium second, a sensor of the multiple second side sensors 119 arranged on the same side as the first side sensor 117 that detected the medium first detects the medium third, and then the other sensor of the multiple first side sensors 117 detects the medium, the determination unit 152 determines whether the skew angle of the medium has changed during transport based on the 12th time from when one of the multiple first side sensors 117 detects the medium to when the other sensor detects the medium.

[0183] This enables the determination unit 152 to determine, early and with high accuracy, that the tilt angle of the medium being transported has changed.

[0184] Furthermore, the determination unit 152 determines whether abnormal skew of the medium has occurred by determining whether abnormal skew condition 1 or abnormal skew condition 2 is satisfied. That is, if one of the second side sensors 119 detects the medium before the first central sensor 114 detects the medium, the determination unit 152 determines that skew has occurred without changing the tilt angle of the medium during transport.

[0185] This allows the determination unit 152 to determine early and with high accuracy whether the medium being transported is being transported so as to collide with a side wall of the transport path.

[0186] As described above in detail, the media transport device is now able to appropriately determine whether the inclination angle of the media is changing during transport, even in a case where there is only one sensor placed in the center of the media transport path.

[0187] 17A and 17B are diagrams showing an example of the data structures of an accumulated skew condition table and an abnormal skew condition table in a medium conveying device according to still another embodiment.

[0188] The medium conveying device according to this embodiment has the same configuration and function as the medium conveying device 100. However, in this embodiment, the medium conveying device does not have the second center sensor 116, and the only sensor arranged in the center of the medium conveying path in the width direction A2 is the first center sensor 114. In addition to the cumulative skew conditions 1 to 4 shown in FIG. 16(A), the cumulative skew condition 5 shown in FIG. 17(A) is set in the cumulative skew condition table. Moreover, in the abnormal skew condition table, instead of the abnormal skew conditions 1 to 2 shown in FIG. 16(B), the abnormal skew condition 1 shown in FIG. 17(B) is set.

[0189] The order condition of cumulative skew condition 5 is set such that one of the multiple first side sensors 117 detects the medium first, the multiple second side sensors 119 that are arranged on the same side as the first side sensor 117 that detected the medium detects the medium second, and the first central sensor 114 detects the medium third. That is, the order condition of cumulative skew condition 1 is set such that the condition of cumulative skew condition 9 shown in FIG. 13A is deleted from the condition of the second central sensor 116 detecting the medium fourth. The time condition of cumulative skew condition 5 is set such that the 14th time from when the first first side sensor 117 detects the medium to when the third first central sensor 114 detects the medium is greater than a 14th threshold T14. The 14th threshold T14 is preset to the time between the 14th time when cumulative skew occurs and the 14th time when abnormal skew occurs when the medium is transported to satisfy the order condition of cumulative skew condition 5.

[0190] On the other hand, the same condition as the order condition of cumulative skew condition 5 is set as the order condition of abnormal skew condition 1. That is, the order condition of abnormal skew condition 1 is set as the order condition of abnormal skew condition 2 shown in Fig. 13(B) except that the condition that the second central sensor 116 detects the medium fourth is deleted. However, the time condition of abnormal skew condition 1 is set such that the 14th time from when the first first side sensor 117 detects the medium to when the third first central sensor 114 detects the medium is equal to or less than a 14th threshold value T14.

[0191] As described above in detail, the medium transport device has one sensor located in the center of the medium transport path, and determines whether cumulative skew or abnormal skew has occurred based on the time between when each sensor detects the medium. In this case, too, the medium transport device is able to appropriately determine whether the tilt angle of the medium is changing during transport.

[0192] 18 is a diagram showing a schematic configuration of a processing circuit 250 in a medium conveying device according to another embodiment. The processing circuit 250 is used in place of the processing circuit 150 of the medium conveying device 100, and executes medium reading processing and the like in place of the processing circuit 150. The processing circuit 250 has a control circuit 251, a determination circuit 252, and the like. Each of these components may be formed of an independent integrated circuit, microprocessor, firmware, and the like.

[0193] The control circuit 251 is an example of a control unit, and has the same functions as the control unit 151. The control circuit 251 receives an operation signal from the operation device 105 or the interface device 132, a placement signal from the placement sensor 111, and a determination result of the cumulative skew or abnormal skew of the medium from the determination circuit 252. The control circuit 251 controls the motor 131 based on each received signal, and also obtains an input image from the imaging device 123 and outputs it to the interface device 132.

[0194] The determination circuit 252 is an example of a determination unit, and has the same function as the determination unit 152. The determination circuit 252 receives a first center signal from the first center sensor 114, an outside area signal from the outside area sensor 115, a second center signal from the second center sensor 116, a first side signal from the first side sensor 117, a thickness signal from the thickness sensor 118, a second side signal from the second side sensor 119, and a third side signal from the third side sensor 122. The determination circuit 252 determines whether or not a cumulative skew and an abnormal skew of the medium have occurred based on each of the received signals, and outputs the determination result to the control circuit 251.

[0195] As described above in detail, even when the processing circuit 250 is used, the medium conveying device is able to appropriately determine whether the tilt angle of the medium being conveyed is changing.

[0196] Although the preferred embodiments have been described above, the embodiments are not limited thereto. For example, the medium conveying device may correct the skew of the medium by making the peripheral speeds of the first conveying roller 120, the second conveying roller 121, the third conveying roller 124, and / or the fourth conveying roller 125 different from one another, instead of the multiple feed rollers 112.

[0197] In the medium conveying device, any one of the plurality of outside area sensors 115, the plurality of first side sensors 117, the plurality of second side sensors 119, and / or the plurality of third side sensors 122 may be omitted.

[0198] Furthermore, the medium conveying device may change the criteria for determining whether or not to perform skew correction and / or the criteria for determining whether or not to perform abnormality processing between when operating in the separation mode and when operating in the non-separation mode. For example, when operating in the separation mode, the control unit 151 performs skew correction of the medium when a cumulative skew of the medium occurs, and when operating in the non-separation mode, the control unit 151 does not perform skew correction of the medium even if a cumulative skew of the medium occurs. This allows the medium conveying device to suppress the occurrence of a medium jam. Alternatively, when operating in the separation mode, the control unit 151 performs skew correction of the medium when a cumulative skew of the medium occurs, and when operating in the non-separation mode, the control unit 151 performs abnormality processing when a cumulative skew of the medium occurs. This allows the medium conveying device to prevent the occurrence of a medium jam. Furthermore, the control unit 151 may set the skew amount threshold when operating in the non-separation mode to be smaller than the skew amount threshold when operating in the separation mode. This allows the medium conveying device to suppress the occurrence of a medium jam.

[0199] Furthermore, the medium conveying device may change the criteria for judging the cumulative skew when operating in the separation mode and when operating in the non-separation mode. For example, the judging unit 152 sets the criterion for judging the cumulative skew when operating in the non-separation mode to be stricter than the criterion for judging the cumulative skew when operating in the separation mode. The judging unit 152 sets the first to fourteenth thresholds T1 to T14 when operating in the non-separation mode to be larger than the first to fourteenth thresholds T1 to T14 when operating in the separation mode to set the criterion to be stricter. This makes it possible for the medium conveying device to prevent the medium from being damaged by overcorrecting the medium.

[0200] The medium conveying device may also have a so-called U-turn path, and feed and convey the media placed on the loading table from the top to the bottom, and discharge the media onto the discharge table. In this case, the feed roller is disposed above the separation roller and facing the separation roller. In this case, the medium conveying device can also appropriately determine whether the inclination angle of the medium is changing during transport. [Explanation of symbols]

[0201] 100 medium conveying device, 112 feeding roller, 113 separation roller, 114 first center sensor, 116 second center sensor, 117 first side sensor, 119 second side sensor, 120 first conveying roller, 121 second conveying roller, 124 third conveying roller, 125 fourth conveying roller, 152 determination unit

Claims

1. a conveying roller for conveying the medium; a first sensor disposed at a center of the medium transport path in a direction perpendicular to the medium transport direction; a second sensor disposed downstream of the first sensor in the medium transport direction and at the center of the medium transport path in a direction perpendicular to the medium transport direction; a third sensor disposed downstream of the second sensor in the medium transport direction and at a first position on either the left or right of the first sensor in a direction perpendicular to the medium transport direction; a determination unit that, when the first sensor detects the medium first, the third sensor detects the medium second, and the second sensor detects the medium third, determines whether or not a transport abnormality has occurred in the transported medium based on the time from when the first sensor detects the medium to when the second sensor detects the medium; A medium transport device comprising:

2. a fourth sensor disposed at a second position downstream of the second sensor in the medium transport direction and opposite to the first position in a direction perpendicular to the medium transport direction; The medium transport device according to claim 1 , wherein the determination unit determines whether a transport abnormality has occurred in the medium being transported based on the time from when the first sensor detects the medium to when the fourth sensor detects the medium.

3. a fifth sensor disposed at a third position downstream of the third sensor in the medium transport direction and on the same side as the first position in a direction perpendicular to the medium transport direction; 2. The medium transport device of claim 1, wherein the determination unit determines whether a transport abnormality has occurred in the medium being transported based on the time from when the first sensor detects the medium to when the fifth sensor detects the medium when the first sensor detects the medium first, the third sensor detects the medium second, and the fifth sensor detects the medium third.

4. The medium transport device according to claim 1 , wherein the determination unit determines that a second transport abnormality has occurred in the medium being transported if the third sensor detects the medium before the first sensor detects the medium.

5. a fifth sensor disposed at a third position downstream of the third sensor in the medium transport direction and on the same side as the first position in a direction perpendicular to the medium transport direction; The medium transport device according to claim 1 , wherein the determination unit determines that a second transport abnormality has occurred in the medium being transported if the fifth sensor detects the medium before the first sensor detects the medium.

6. a conveying roller for conveying the medium; a first sensor disposed at a center of the medium transport path in a direction perpendicular to the medium transport direction; a second sensor disposed downstream of the first sensor in the medium transport direction and at a first position on either the left or right of the first sensor in a direction perpendicular to the medium transport direction; a third sensor disposed at a second position downstream of the second sensor in the medium transport direction and on the same side as the first position in a direction perpendicular to the medium transport direction; a determination unit that, when one of the first sensor and the second sensor detects the medium first, the other of the first sensor and the second sensor detects the medium second, and the third sensor detects the medium third, determines whether or not a transport abnormality has occurred in the medium being transported based on the time from when the one sensor detects the medium to when the third sensor detects the medium; A medium transport device comprising:

7. a fourth sensor disposed at a third position downstream of the first sensor in the medium transport direction and opposite the first position in a direction perpendicular to the medium transport direction; The medium transport device according to claim 6 , wherein the determination unit determines whether a transport abnormality has occurred in the medium being transported based on the time from when the one sensor detects the medium to when the fourth sensor detects the medium.

8. The medium transport device according to claim 6 , wherein the determination unit determines that a second transport abnormality has occurred in the medium being transported if the third sensor detects the medium before the first sensor detects the medium.

9. a conveying roller for conveying the medium; a central sensor disposed at a central portion of the medium transport path in a direction perpendicular to the medium transport direction; a side sensor disposed downstream of the central sensor in the medium transport direction and at a first position on either the left or right of the central sensor in a direction perpendicular to the medium transport direction; a determination unit that determines whether a transport abnormality has occurred in the medium being transported, At least one of the central sensor and the side sensor includes two sensors arranged at different positions in a medium transport direction, The determination unit determines whether a transport abnormality has occurred in the transported medium based on which of the sensors first, second, and third detected the medium, and the time from when the first sensor detected the medium to when the third sensor detected the medium. A medium transport device characterized by:

10. A method for controlling a medium transport device having a transport roller that transports a medium, a first sensor arranged in a center of a medium transport path in a direction perpendicular to the medium transport direction, a second sensor arranged downstream of the first sensor in the medium transport direction and in a center of the medium transport path in the direction perpendicular to the medium transport direction, and a third sensor arranged downstream of the second sensor in the medium transport direction and at a first position on either the left or right of the first sensor in the direction perpendicular to the medium transport direction, When the first sensor detects the medium first, the third sensor detects the medium second, and the second sensor detects the medium third, it is determined whether or not a transport abnormality has occurred in the transported medium based on the time from when the first sensor detects the medium to when the second sensor detects the medium. A control method comprising:

11. A method for controlling a medium transport device having a transport roller that transports a medium, a first sensor arranged in a center of a medium transport path in a direction perpendicular to the medium transport direction, a second sensor arranged at a first position downstream of the first sensor in the medium transport direction and on either the left or right of the first sensor in the direction perpendicular to the medium transport direction, and a third sensor arranged at a second position downstream of the second sensor in the medium transport direction and on the same side as the first position in the direction perpendicular to the medium transport direction, When one of the first sensor and the second sensor detects the medium first, the other of the first sensor and the second sensor detects the medium second, and the third sensor detects the medium third, it is determined whether or not a transport abnormality has occurred in the transported medium based on the time from when the one sensor detects the medium to when the third sensor detects the medium. A control method comprising:

12. A method for controlling a medium transport device having a transport roller that transports a medium, a central sensor that is arranged in a central portion of a medium transport path in a direction perpendicular to the medium transport direction, and a side sensor that is arranged downstream of the central sensor in the medium transport direction and at a first position on either the left or right of the central sensor in the direction perpendicular to the medium transport direction, wherein at least one of the central sensor and the side sensor includes two sensors that are arranged at mutually different positions in the medium transport direction, A determination is made as to whether or not a transport abnormality has occurred in the transported medium based on which of the sensors first, second, and third detected the medium, and the time from when the first sensor detected the medium to when the third sensor detected the medium. A control method comprising:

13. A control program for a medium transport device having a transport roller that transports a medium, a first sensor arranged in a center of a medium transport path in a direction perpendicular to the medium transport direction, a second sensor arranged downstream of the first sensor in the medium transport direction and in a center of the medium transport path in the direction perpendicular to the medium transport direction, and a third sensor arranged downstream of the second sensor in the medium transport direction and at a first position on either the left or right of the first sensor in the direction perpendicular to the medium transport direction, When the first sensor detects the medium first, the third sensor detects the medium second, and the second sensor detects the medium third, it is determined whether or not a transport abnormality has occurred in the transported medium based on the time from when the first sensor detects the medium to when the second sensor detects the medium. a control program for causing the medium transport device to execute the above steps;

14. A control program for a medium transport device having a transport roller that transports a medium, a first sensor arranged in a center of a medium transport path in a direction perpendicular to the medium transport direction, a second sensor arranged at a first position downstream of the first sensor in the medium transport direction and on either the left or right of the first sensor in the direction perpendicular to the medium transport direction, and a third sensor arranged at a second position downstream of the second sensor in the medium transport direction and on the same side as the first position in the direction perpendicular to the medium transport direction, When one of the first sensor and the second sensor detects the medium first, the other of the first sensor and the second sensor detects the medium second, and the third sensor detects the medium third, it is determined whether or not a transport abnormality has occurred in the transported medium based on the time from when the one sensor detects the medium to when the third sensor detects the medium. a control program for causing the medium transport device to execute the above steps;

15. A control program for a medium transport device having a transport roller that transports a medium, a central sensor that is arranged in a central portion of a medium transport path in a direction perpendicular to the medium transport direction, and a side sensor that is arranged downstream of the central sensor in the medium transport direction and at a first position on either the left or right of the central sensor in the direction perpendicular to the medium transport direction, wherein at least one of the central sensor and the side sensor includes two sensors that are arranged at mutually different positions in the medium transport direction, A determination is made as to whether or not a transport abnormality has occurred in the transported medium based on which of the sensors first, second, and third detected the medium, and the time from when the first sensor detected the medium to when the third sensor detected the medium. a control program for causing the medium transport device to execute the above steps;

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