Medium ejection device, control method, and control program

Abstract

Provided are a medium ejection device, a control method, and a control program with which it is possible to satisfactorily eject a medium. The medium ejection device comprises: an imaging unit; a plurality of ejection rollers disposed on the downstream side of the imaging unit in the medium ejecting direction at intervals in a direction orthogonal to the medium ejecting direction; a plurality of detection sensors disposed between the imaging unit and the plurality of ejection rollers at intervals in a direction orthogonal to the medium ejecting direction; and a control unit that conveys a medium captured by the imaging unit with the plurality of ejection rollers having peripheral velocities different from each other to execute skew correction of the medium. The control unit executes the skew correction if the elapsed time from passage of the rear end of the medium through one of the plurality of detection sensors to passage through another detection sensor is less than or equal to a first threshold, and does not execute the skew correction if the elapsed time is greater than the first threshold.

Description

[Technical Field]

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

[0002] A media ejection device, such as a scanner, sequentially transports and captures images of multiple media, then ejects them onto a tray. If media skew occurs in such a media ejection device, the media ejected onto the tray will not be aligned, and the user will need to straighten them. However, if the media ejection device attempts to forcibly correct the skew of the media to align the media ejected onto the tray, stress will be placed on the media, potentially damaging them.

[0003] An image reading device has been disclosed that has an image reading means for reading an image on a fed sheet, a paper discharge stacking means for placing the sheet, and a plurality of individually controllable paper discharge rollers located upstream of the paper discharge stacking means (see Patent Document 1). This image reading device detects the amount of skew of the sheet, and rotates the plurality of paper discharge rollers at different speeds based on the detected amount of skew so as to correct the amount of skew of the sheet.

[0004] A sheet skew correction conveying device has been disclosed that includes a skew detection sensor and a side edge detection sensor that detect skew of a sheet being conveyed, and a skew roller that can correct the skew of the sheet while conveying the sheet (see Patent Document 2). This sheet skew correction conveying device causes the skew roller to perform a skew correction operation based on skew detection by the skew detection sensor, and then causes the skew roller to perform a skew correction operation based on skew detection of the sheet by the side edge detection sensor. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2017-208628 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-335516 Summary of the Invention

[0006] A medium ejection device is required to eject media smoothly.

[0007] The object of the medium ejection device, control method, and control program according to the embodiment is to enable the medium to be ejected properly.

[0008] A media discharge device according to one aspect of the embodiment includes an imaging unit, a plurality of discharge rollers arranged downstream of the imaging unit in the media discharge direction and spaced apart in a direction perpendicular to the media discharge direction, a plurality of detection sensors arranged between the imaging unit and the plurality of discharge rollers and spaced apart in a direction perpendicular to the media discharge direction, and a control unit that performs skew correction of the media by varying the peripheral speeds of the plurality of discharge rollers to transport the media imaged by the imaging unit, and the control unit performs skew correction if the elapsed time from when the rear end of the media passes one of the plurality of detection sensors to when it passes the other detection sensor is less than or equal to a first threshold, and does not perform skew correction if the elapsed time is greater than the first threshold.

[0009] Furthermore, a control method according to one aspect of the embodiment is a control method for a media discharge device, which includes performing skew correction of a medium by making the peripheral speeds of multiple discharge rollers arranged downstream of an imaging unit in the media discharge direction and spaced apart in a direction perpendicular to the media discharge direction different from each other, and transporting the medium imaged by the imaging unit, and in performing skew correction, if the elapsed time from when the rear end of the medium passes one of multiple detection sensors arranged between the imaging unit and the multiple discharge rollers and spaced apart in a direction perpendicular to the media discharge direction to when it passes the other detection sensor is less than or equal to a first threshold value, skew correction is performed, and if the elapsed time is greater than the first threshold value, skew correction is not performed.

[0010] Furthermore, a control program according to one aspect of the embodiment is a control program for a media discharge device having an imaging unit, a plurality of discharge rollers arranged downstream of the imaging unit in a direction perpendicular to the media discharge direction at intervals, and a plurality of detection sensors arranged between the imaging unit and the plurality of discharge rollers at intervals in a direction perpendicular to the media discharge direction, and causes the media discharge device to perform skew correction of the media by making the peripheral speeds of the plurality of discharge rollers different from each other and transporting the media imaged by the imaging unit, and in performing skew correction, if the elapsed time from when the rear end of the media passes one of the plurality of detection sensors arranged at intervals in a direction perpendicular to the media discharge direction between the imaging unit and the plurality of discharge rollers to when it passes the other detection sensor is less than or equal to a first threshold value, skew correction is performed, and if the elapsed time is greater than the first threshold value, skew correction is not performed.

[0011] According to this embodiment, the medium ejection device, control method, and control program are capable of ejecting the medium properly.

[0012] The objects and advantages of the invention will be realized and obtained by means of the elements and combinations particularly pointed out in the claims. Both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention as claimed. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a perspective view showing a medium ejection device 100 according to an embodiment. [Figure 2] 2 is a diagram for explaining a transport path inside the medium ejection device 100. FIG. [Figure 3] 3 is a schematic diagram for explaining the arrangement positions of each medium sensor; FIG. [Figure 4] 1 is a block diagram showing a schematic configuration of a medium ejection device 100. FIG. [Figure 5] FIG. 2 is a diagram showing a schematic configuration of a storage device 140 and a processing circuit 150. [Figure 6] 10 is a flowchart illustrating an example of the operation of a medium reading process. [Figure 7] 10 is a flowchart illustrating an example of the operation of a medium reading process. [Figure 8] FIG. 2 is a schematic diagram showing an example of a partial image N. [Figure 9] 10 is a flowchart illustrating an example of a portion of the operation of another medium reading process. [Figure 10] 10 is a flowchart illustrating an example of a portion of the operation of another medium reading process. [Figure 11] FIG. 10 is a schematic diagram for explaining skew correction of a medium. [Figure 12] 10 is a flowchart illustrating an example of a portion of the operation of another medium reading process. [Figure 13] 10 is a schematic diagram for explaining another medium ejection device 200. FIG. [Figure 14] 10 is a flowchart showing another example of the operation of the medium reading process. [Figure 15] 10 is a flowchart illustrating an example of an operation of a detection process. [Figure 16] 10A and 10B are schematic diagrams for explaining the state of a medium to be ejected; [Figure 17] 10A and 10B are schematic diagrams for explaining the state of a medium to be ejected; [Figure 18] (A) is an example of a graph 1800, and (B) is an example of a graph 1810. [Figure 19] (A) is an example of a graph 1900, and (B) is an example of a graph 1910. [Figure 20] (A) is an example of a graph 2000, and (B) is an example of a graph 2010. [Figure 21] 21 is an example of a graph 2100. [Figure 22] 10A and 10B are schematic diagrams for explaining the state of a medium to be ejected; [Figure 23] FIG. 10 is a diagram showing a schematic configuration of another processing circuit 350. DETAILED DESCRIPTION OF THE INVENTION

[0014] A medium ejection device, a control method, and a control program according to one aspect of the present disclosure will be described below with reference to the accompanying drawings. However, please note that the technical scope of the present invention is not limited to the embodiments described above, but extends to the inventions set forth in the claims and their equivalents.

[0015] FIG. 1 is a perspective view showing a medium ejection device 100 configured as an image scanner. The medium ejection device 100 transports, captures an image of, and ejects a medium that is an original. The medium may be paper, cardboard, a card, a booklet, a passport, or the like. The medium ejection device 100 may also be a facsimile machine, a copier, a multifunction peripheral (MFP), or the like.

[0016] 1, arrow A1 indicates the medium ejection direction, arrow A2 indicates the width direction perpendicular to the medium ejection direction, and arrow A3 indicates the height direction perpendicular to the medium transport path. In the following, "upstream" refers to the upstream side of the medium ejection direction A1, and "downstream" refers to the downstream side of the medium ejection direction A1.

[0017] The medium ejection device 100 includes a lower housing 101, an upper housing 102, a mounting table 103, an ejection table 104, an operation device 105, a display device 106, and the like.

[0018] The upper housing 102 is disposed in a position that covers the top surface of the medium ejection device 100, and is engaged with the lower housing 101 by a hinge so that it can be opened and closed when a medium is jammed or when cleaning the inside of the medium ejection device 100, for example.

[0019] The placement stage 103 engages with the lower housing 101 and places media to be fed and transported on it. The ejection stage 104 engages with the upper housing 102 and places ejected media on it. Note that the ejection stage 104 may also engage with the lower housing 101.

[0020] The operation device 105 has input devices such as buttons and an interface circuit for acquiring signals from the input devices, accepts input operations by a user, and outputs operation signals in response to the user's input operations. The display device 106 has a display such as a liquid crystal display, an organic EL (Electro-Luminescence) display, or the like, and an interface circuit for outputting image data to the display, and displays the image data on the display.

[0021] FIG. 2 is a diagram for explaining the transport path inside the medium ejection device 100. As shown in FIG.

[0022] The transport path inside the media discharge device 100 includes a first media sensor 111, a feed roller 112, a separation roller 113, a second media sensor 114, a third media sensor 115, a fourth media sensor 116, a first transport roller 117, a second transport roller 118, an imaging device 119, a fifth media sensor 120, a first discharge roller 121, and a second discharge roller 122, etc.

[0023] The number of each of the feed roller 112, separation roller 113, first conveyance roller 117, second conveyance roller 118, first discharge roller 121, and / or second discharge roller 122 is not limited to one, and may be more than one. In this case, the multiple feed rollers 112, separation rollers 113, first conveyance roller 117, second conveyance roller 118, first discharge roller 121, and / or second discharge roller 122 are arranged at intervals in the width direction A2, which is perpendicular to the medium discharge direction A1.

[0024] The top surface of lower housing 101 forms lower guide 107a of the medium transport path, and the bottom surface of upper housing 102 forms upper guide 107b of the medium transport path. As shown in Figure 2, the medium transport path has a so-called straight path mechanism in which the vertical positional relationship between the front and back surfaces of the medium does not change between the state before transport when the medium is placed on loading tray 103 and the state after ejection when the medium is placed on ejection tray 104. Because the medium transport path has a straight path mechanism, medium ejection device 100 can be formed compactly.

[0025] The first medium sensor 111 is disposed upstream of the feed roller 112 and the separation roller 113. The first medium sensor 111 has a contact detection sensor and detects whether or not a medium is placed on the placement table 103. The first medium sensor 111 generates and outputs a first medium signal whose signal value changes depending on whether or not a medium is placed on the placement table 103. Note that the first medium sensor 111 is not limited to a contact detection sensor, and any other sensor capable of detecting the presence or absence of a medium, such as an optical detection sensor, may be used as the first medium sensor 111.

[0026] The feed roller 112 is provided in the lower housing 101 and feeds the media placed on the mounting table 103 in order from the bottom up. The separation roller 113 is provided in the upper housing 102 and is disposed opposite the feed roller 112. Alternatively, the feed roller 112 may be provided in the upper housing 102 and the separation roller 113 in the lower housing 101, and the feed roller 112 may feed the media placed on the mounting table 103 in order from the top up.

[0027] The first conveying roller 117 and the second conveying roller 118 are disposed facing each other downstream of the feeding roller 112. The first conveying roller 117 and the second conveying roller 118 convey the medium fed by the feeding roller 112 and the separation roller 113 to the imaging device 119.

[0028] The imaging device 119 is an example of an imaging section, and includes a first imaging device 119a and a second imaging device 119b that are arranged opposite each other across the medium transport path.

[0029] The first imaging device 119a includes a first imaging sensor 119c, which is a CIS (Contact Image Sensor) with a 1x magnification optical system and has CMOS (Complementary Metal Oxide Semiconductor) imaging elements linearly arranged in the main scanning direction. The first imaging sensor 119c images the surface of the medium at a first imaging position P1. The first imaging position P1 is an example of a first position, and the surface of the medium is an example of a first surface. The first imaging device 119a also includes 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 119a captures an area of ​​the surface of the transported medium facing the first imaging sensor 119c at regular intervals, sequentially generating and outputting input images. That is, the input image has one pixel in the vertical direction (sub-scanning direction) and multiple pixels in the horizontal direction (main scanning direction).

[0030] Similarly, the second imaging device 119b has a second imaging sensor 119d that is a CIS-based, life-size optical system with CMOS imaging elements linearly arranged in the main scanning direction. The second imaging sensor 119d images the back surface of the medium at a second imaging position P2 downstream of the first imaging position P1 in the medium ejection direction A1. The second imaging position P2 is an example of a second position, and the back surface of the medium is an example of a second surface. The second imaging position P2 downstream of the first imaging position P1 is an example of an imaging position by the imaging device 119. The second imaging device 119b 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 119b captures an area of ​​the front surface of the transported medium facing the second imaging sensor 119d at regular intervals, sequentially generating and outputting input images.

[0031] The medium ejection device 100 may be configured with only one of the first and second imaging devices 119a and 119b, and may read only one side of the medium. Alternatively, the first and / or second imaging sensors 119c and 119d may be CIS line sensors with a life-size optical system equipped with a CCD (Charge Coupled Device) imaging element. Alternatively, the first and / or second imaging sensors 119c and 119d may be CMOS or CCD line sensors with a reduced optical system. The first and second imaging sensors 119c and 119d may be positioned such that the second imaging sensor 119d captures an image of the back side of the medium at the first imaging position P1, and the first imaging sensor 119c captures an image of the front side of the medium at the second imaging position P2 downstream from the first imaging position P1. In this case, the back side of the medium is an example of the first side, and the front side of the medium is an example of the second side.

[0032] The first discharge roller 121 and the second discharge roller 122 are arranged facing each other downstream of the imaging device 119 in the medium discharge direction A1. The first discharge roller 121 and the second discharge roller 122 discharge the medium that has been transported by the first conveyance roller 117 and the second conveyance roller 118 and that has been imaged by the imaging device 119 onto the discharge tray 104. The first discharge roller 121 and / or the second discharge roller 122 are examples of discharge rollers. Hereinafter, the first discharge roller 121 and / or the second discharge roller 122 may be collectively referred to as discharge rollers.

[0033] The media placed on the mounting table 103 is transported between the lower guide 107a and the upper guide 107b in the media discharge direction A1 by the rotation of the feed roller 112 in the direction of arrow A4 in Figure 2, i.e., the media feed direction. When transporting the media, the separation roller 113 rotates in the direction of arrow A5, i.e., the opposite direction to the media feed direction. When multiple media are placed on the mounting table 103, the feed roller 112 and the separation roller 113 work to separate only the media placed on the mounting table 103 that are in contact with the feed roller 112. This restricts the transport of media other than the separated media (preventing double feeding).

[0034] The medium is fed between the first conveyance roller 117 and the second conveyance roller 118 while being guided by the lower guide 107a and the upper guide 107b. The medium is fed between the first imaging device 119a and the second imaging device 119b as the first conveyance roller 117 and the second conveyance roller 118 rotate in the directions of arrows A6 and A7, respectively. The medium read by the imaging device 119 is discharged onto the discharge tray 104 as the first discharge roller 121 and the second discharge roller 122 rotate in the directions of arrows A8 and A9, respectively. The discharge tray 104 holds the media discharged by the first discharge roller 121 and the second discharge roller 122.

[0035] 3 is a schematic diagram for explaining the arrangement positions of the rollers and the media sensors, and is a schematic diagram of the lower housing 101 in the open state, as seen from the transport path side.

[0036] In the example shown in FIG. 3, two each of the feeding roller 112, separation roller 113, first conveying roller 117, second conveying roller 118, first discharge roller 121 and second discharge roller 122 are arranged.

[0037] The second medium sensor 114 and the third medium sensor 115 are an example of a plurality of second sensors. The second medium sensor 114 and the third medium sensor 115 are arranged downstream of the feed roller 112 and the separation roller 113 in the medium discharge direction A1 and upstream of the imaging device 119, and are spaced apart in the width direction A2 perpendicular to the medium discharge direction. The second medium sensor 114 and the third medium sensor 115 are arranged so that the distance W in the width direction A2 between the second medium sensor 114 and the third medium sensor 115 is less than the minimum width of the medium supported by the medium discharge device 100. In the example shown in FIG. 3 , the second medium sensor 114 and the third medium sensor 115 are arranged upstream of the first conveyor roller 117 and the second conveyor roller 118. Note that the second medium sensor 114 and the third medium sensor 115 may also be arranged downstream of the first conveyor roller 117 and the second conveyor roller 118. The second medium sensor 114 and the third medium sensor 115 detect the leading and trailing edges of the medium transported to that position.

[0038] The second medium sensor 114 includes a light emitter and a light receiver provided on one side of the medium transport path, and a light guide member provided opposite the light emitter and light receiver across the medium transport path. The light guide member is a light guide tube such as a U-shaped prism. The light emitter is an LED (Light Emitting Diode) or the like and emits light toward the transport path. The light receiver is a photodiode or the like and receives the light emitted by the light emitter and guided by the light guide member. When a medium is present in a position opposite the second medium sensor 114, the light emitted from the light emitter is blocked by the medium, and the light receiver does not detect the light emitted from the light emitter. The light receiver generates and outputs a second medium signal based on the intensity of the received light. The signal value changes depending on whether a medium is present or not at the second medium sensor 114. The second medium signal is an example of an output signal from the second medium sensor 114.

[0039] Similarly, the third medium sensor 115 includes a light emitter and a light receiver provided on one side of the medium transport path, and a light guide member provided opposite the light emitter and light receiver across the medium transport path. The light guide member is a light guide tube such as a U-shaped prism. The light emitter is an LED or the like and emits light toward the transport path. Meanwhile, the light receiver is a photodiode or the like and receives the light emitted by the light emitter and guided by the light guide member. Based on the intensity of the received light, the light receiver generates and outputs a third medium signal whose signal value changes depending on whether a medium is present or not at the position of the third medium sensor 115. The third medium signal is an example of an output signal from the third medium sensor 115.

[0040] The fourth medium sensor 116 is disposed downstream of the feed roller 112 and the separation roller 113 in the medium discharge direction A1 and upstream of the imaging device 119. The fourth medium sensor 116 is disposed in the center in the width direction A2, which is perpendicular to the medium discharge direction, particularly between the two first conveyance rollers 117 and between the two second conveyance rollers 118. In the example shown in FIG. 3 , the fourth medium sensor 116 is disposed downstream of the second medium sensor 114 and the third medium sensor 115 and upstream of the first conveyance roller 117 and the second conveyance roller 118. The fourth medium sensor 116 may be disposed in the same position as the second medium sensor 114 and the third medium sensor 115 in the medium discharge direction A1, or upstream of the second medium sensor 114 and the third medium sensor 115. The fourth medium sensor 116 may also be disposed downstream of the first conveyance roller 117 and the second conveyance roller 118. The fourth media sensor 116 detects the leading and trailing edges of the media transported to that position.

[0041] The fourth medium sensor 116 includes a light emitter and a light receiver provided on one side of the medium transport path, and a light guide member provided opposite the light emitter and light receiver across the medium transport path. The light guide member is a light guide tube such as a U-shaped prism. The light emitter is an LED or the like and emits light toward the transport path. Meanwhile, the light receiver is a photodiode or the like and receives the light emitted by the light emitter and guided by the light guide member. Based on the intensity of the received light, the light receiver generates and outputs a fourth medium signal whose signal value changes depending on whether a medium is present or not at the position of the fourth medium sensor 116.

[0042] The fifth medium sensor 120 is an example of a sensor, and is disposed between the imaging device 119 and the first and second discharge rollers 121 and 122. That is, the fifth medium sensor 120 is disposed downstream of the imaging device 119 in the medium discharge direction A1 and upstream of the first and second discharge rollers 121 and 122. The fifth medium sensor 120 is also disposed in the center in the width direction A2, which is perpendicular to the medium discharge direction, particularly between the two first discharge rollers 121 and between the two second discharge rollers 122. The fifth medium sensor 120 detects the leading and trailing edges of a medium transported to that position.

[0043] The fifth media sensor 120 includes a light emitter and a light receiver provided on one side of the media transport path, and a light guide member provided opposite the light emitter and light receiver across the media transport path. The light guide member is a light guide tube such as a U-shaped prism. The light emitter is an LED or the like and emits light toward the transport path. Meanwhile, the light receiver is a photodiode or the like and receives the light emitted by the light emitter and guided by the light guide member. Based on the intensity of the received light, the light receiver generates and outputs a fifth media signal whose signal value changes depending on whether a media is present or not at the position of the fifth media sensor 120.

[0044] Note that a reflective member such as a mirror may be used instead of a light-guiding member in second medium sensor 114, third medium sensor 115, fourth medium sensor 116, and / or fifth medium sensor 120. Also, in second medium sensor 114, third medium sensor 115, fourth medium sensor 116, and / or fifth medium sensor 120, the light emitter and light receiver may be positioned opposite each other across the transport path. Also, second medium sensor 114, third medium sensor 115, fourth medium sensor 116, and / or fifth medium sensor 120 may detect the presence of a medium using a contact detection sensor or the like that passes a predetermined current when the medium is in contact or not in contact.

[0045] FIG. 4 is a block diagram showing a schematic configuration of the medium ejection device 100. As shown in FIG.

[0046] In addition to the above-described components, the medium ejection device 100 further includes a motor 131, an interface device 132, a storage device 140, a processing circuit 150, and the like.

[0047] The motor 131 has one or more motors, and rotates the feed roller 112, separation roller 113, first conveyance roller 117, second conveyance roller 118, first discharge roller 121, and second discharge roller 122 to convey the medium in response to a control signal from the processing circuit 150. Note that one of the first conveyance roller 117 and second conveyance roller 118 may be a driven roller that rotates following the rotation of the other roller. Also, one of the first discharge roller 121 and second discharge roller 122 may be a driven roller that rotates following the rotation of the other roller.

[0048] 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 personal digital assistant, etc.) to transmit and receive input images and various information. Alternatively, 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 via a wireless communication line in accordance with a predetermined communication protocol may be used. The predetermined communication protocol is, for example, a wireless LAN (Local Area Network). The communication unit may have a wired communication interface device for transmitting and receiving signals via a wired communication line in accordance with a communication protocol such as a wired LAN.

[0049] Storage device 140 includes a memory device such as RAM (Random Access Memory) or ROM (Read Only Memory), a fixed disk device such as a hard disk, or a portable storage device such as a flexible disk or optical disk. Storage device 140 also stores computer programs, databases, tables, and the like used for various processes of medium ejection device 100. Computer programs may be installed into storage device 140 from a computer-readable portable recording medium using a known setup program or the like. Portable recording media include, for example, CD-ROMs (compact disc read only memory) and DVD-ROMs (digital versatile disc read only memory).

[0050] The processing circuit 150 operates based on a program stored in advance in the storage device 140. The processing circuit is, for example, a CPU (Central Processing Unit). The processing circuit 150 may be a DSP (Digital Signal Processor), an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or the like.

[0051] The processing circuit 150 is connected to the operation device 105, the display device 106, the first medium sensor 111, the second medium sensor 114, the third medium sensor 115, the fourth medium sensor 116, the imaging device 119, the fifth medium sensor 120, the motor 131, the interface device 132, the storage device 140, and the like, and controls each of these components. The processing circuit 150 controls the drive of the motor 131, controls the imaging of the imaging device 119, and so on, and acquires an input image from the imaging device 119 to generate a medium image, which is then transmitted to the information processing device via the interface device 132. The processing circuit 150 also detects the amount of tilt of the medium based on the input image, and when a portion of the trailing edge of the medium passes the position of the fifth medium sensor 120, determines, based on the amount of tilt, whether the entire trailing edge of the medium has passed the imaging position of the imaging device 119. The processing circuit 150 controls the first discharge roller 121 and / or the second discharge roller 122 based on the determination result.

[0052] FIG. 5 is a diagram showing a schematic configuration of the storage device 140 and the processing circuit 150. As shown in FIG.

[0053] 5, the storage device 140 stores a control program 141, a detection program 142, a determination program 143, a skew determination program 144, etc. Each of these programs is a functional module implemented by software running on a processor. The processing circuit 150 reads each program stored in the storage device 140 and operates in accordance with the read program. As a result, the processing circuit 150 functions as a control unit 151, a detection unit 152, a determination unit 153, and a skew determination unit 154.

[0054] 6 and 7 are flowcharts showing an example of the operation of the medium reading process of the medium ejection device 100. FIG.

[0055] 6 and 7, an example of the operation of the medium reading process of medium ejection device 100 will be described. Note that the flow of the operation described below is executed mainly by processing circuit 150 in cooperation with each element of medium ejection device 100 based on a program stored in advance in storage device 140.

[0056] First, the control unit 151 waits until the user inputs an instruction to read a medium using the operation device 105 or the information processing device, and an operation signal instructing the reading of a medium is received from the operation device 105 or the interface device 132 (step S101).

[0057] Next, control unit 151 acquires a first medium signal from first medium sensor 111, and determines whether or not a medium is placed on mounting table 103 based on the acquired first medium signal (step S102). If no medium is placed on mounting table 103, control unit 151 ends the series of steps.

[0058] On the other hand, when a medium is placed on the placement table 103, the control unit 151 drives the motor 131. The control unit 151 rotates the feed roller 112, the separation roller 113, the first conveyance roller 117, the second conveyance roller 118, the first discharge roller 121, and / or the second discharge roller 122 to convey the medium (step S103).

[0059] Next, control unit 151 waits until the leading edge of the transported medium passes the position of fourth medium sensor 116 (step S104). Control unit 151 periodically acquires a fourth medium signal from fourth medium sensor 116, and determines that the leading edge of the medium has passed the position of fourth medium sensor 116 when the signal value of the fourth medium signal changes from a value indicating that no medium is present to a value indicating that a medium is present.

[0060] When the leading edge of the transported medium passes the position of fourth medium sensor 116, control unit 151 causes imaging device 119 to start capturing an image of the medium (step S105). Thereafter, control unit 151 acquires an input image from imaging device 119 at regular intervals (each time imaging device 119 generates an input image) and stores the input image in storage device 140.

[0061] Next, the control unit 151 waits until a portion of the trailing edge of the transported medium passes the first imaging position P1 of the first imaging sensor 119c, which is located upstream of the second imaging sensor 119d (step S106). The control unit 151 periodically acquires a fourth medium signal from the fourth medium sensor 116, and determines that the trailing edge of the medium has passed the position of the fourth medium sensor 116 when the signal value of the fourth medium 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 a portion of the trailing edge of the medium has passed the first imaging position P1 when a first predetermined time has elapsed since the trailing edge of the medium passed the position of the fourth medium sensor 116. The first predetermined time is set to a value obtained by adding or subtracting a margin from the time required for the medium to move from the fourth medium sensor 116 to the first imaging position P1. Note that the control unit 151 may also determine that a portion of the trailing edge of the medium has passed the first imaging position P1 when a predetermined time has elapsed since the start of medium feeding.

[0062] When a part of the rear end of the medium has passed the first imaging position P1, the control unit 151 combines the input images acquired up to now from the first imaging device 119a to generate a partial image (step S107).

[0063] FIG. 8 is a schematic diagram showing an example of the partial image N.

[0064] Partial image N shown in FIG. 8 includes medium M1 that was transported tilted. However, because medium M1 is tilted, a portion of the rear end of medium M1 is not included in partial image N. Because partial image N is used to calculate the tilt angle (amount of tilt) θ of medium M1, partial image N does not need to include the entire rear end of medium M1. By generating partial image N at a point in time when only a portion of the rear end of medium M1 is included, the control unit 151 can enable medium discharge device 100 to detect the amount of tilt θ of the medium at an early stage.

[0065] Next, the detection unit 152 detects the amount of tilt θ of the medium from the partial image N (step S108). That is, the detection unit 152 detects the amount of tilt θ of the medium based on the input image captured by the first image sensor 119c, whose imaging position is upstream of the second image sensor 119d. This allows the detection unit 152 to detect the amount of tilt of the medium more quickly.

[0066] The detection unit 152 first calculates, for each vertical line extending vertically (sub-scanning direction) within a predetermined range R from the bottom edge of the partial image N, the absolute value of the difference in gradation values ​​between the pixels on both sides of each pixel in the vertical direction (hereinafter referred to as the adjacent difference value), starting from the bottom. The predetermined range R is set to a range that reliably includes the rear end of the medium (for example, a range of 1,000 pixels). The detection unit 152 detects pixels in each vertical line whose adjacent difference value exceeds a gradation threshold as edge pixels. The gradation value may be a brightness value or a color value (R value, G value, or B value). The gradation threshold is set, for example, to a brightness value difference (for example, 20) that allows a person to visually distinguish differences in brightness on an image. The detection unit 152 detects the edge pixel located at the bottom of each vertical line as the bottom edge pixel.

[0067] The detection unit 152 may calculate, as the adjacent difference value, the absolute value of the difference in gradation values ​​between two pixels that are a predetermined distance away from each pixel in the horizontal or vertical direction. The detection unit 152 may also detect edge pixels by comparing the gradation value of each pixel with a threshold. For example, if the gradation value of a specific pixel is less than the threshold, and the gradation value of a pixel that is adjacent to the specific pixel in the horizontal or vertical direction or a pixel that is a predetermined distance away from the specific pixel is equal to or greater than the threshold, the detection unit 152 detects the specific pixel as an edge pixel.

[0068] Next, the detection unit 152 detects a straight line (line segment) from the bottom edge pixels using the least squares method as the bottom edge of the medium. The detection unit 152 may also detect the straight line using a Hough transform. Furthermore, when multiple straight lines are detected from the bottom edge pixels, the detection unit 152 may detect the straight line with the longest length in the horizontal direction (main scanning direction) as the bottom edge of the medium. In the example shown in FIG. 8, straight lines C1 and C2 are detected from the bottom edge pixels, and straight line C2 with the longest length in the horizontal direction (main scanning direction) is detected as the bottom edge of the medium. The detection unit 152 detects the angle θ between the detected straight line (bottom edge of the medium) and the horizontal direction as the amount of tilt of the medium.

[0069] Next, the detection unit 152 estimates the amount of positional deviation in the medium discharge direction A1 between the end position B1 of the trailing edge of the medium on the side where progress is delayed and the position B2 opposite the fifth medium sensor 120 (step S109).

[0070] Based on the tilt of the bottom edge of the medium, the detection unit 152 identifies the edge on the left or right side of the trailing edge of the medium that is slower to move. Similar to the process of step S109, the detection unit 152 detects an edge edge pixel B3 corresponding to the identified edge within a bottom edge line extending horizontally (main scanning direction) that is located at the bottommost position of partial image N in the vertical direction (sub-scanning direction) within the partial image. The detection unit 152 calculates adjacent difference values ​​within the bottom edge line in order from the identified edge side, and detects the pixel whose adjacent difference value first exceeds the gradation threshold as edge edge pixel B3.

[0071] The detection unit 152 calculates the horizontal distance x between the detected end edge pixel B3 and pixel B4 corresponding to the fifth media sensor 120 within the bottom edge line. The horizontal position of pixel B4 corresponding to the fifth media sensor 120 within the bottom edge line is set in advance based on the positional relationship between the first imaging position P1 of the first imaging sensor 119c and the arrangement position of the fifth media sensor 120. Next, the detection unit 152 calculates (estimates) the vertical positional deviation y on the partial image between the end position B1 on the side where the media's trailing edge is lagging and the position B2 facing the fifth media sensor 120, based on the horizontal distance x and the tilt amount θ, using the following approximate formula (1): y≒x·tanθ (1)

[0072] Based on the resolution of the partial image, the detection unit 152 calculates the amount of positional deviation in the media discharge direction A1 in real space between the end position B1 on the side where progress is delayed at the rear end of the media and the position B2 opposite the fifth media sensor 120, which corresponds to the amount of positional deviation y on the partial image.

[0073] Next, determination unit 153 waits until part of the trailing edge of the transported medium passes the position of fifth medium sensor 120 (step S201). Determination unit 153 periodically acquires a fifth medium signal from fifth medium sensor 120, and determines that part of the trailing edge of the medium has passed the position of fifth medium sensor 120 when the signal value of the fifth medium signal changes from a value indicating the presence of a medium to a value indicating the absence of a medium.

[0074] When part of the trailing edge of the medium passes the position of the fifth medium sensor 120, the determination unit 153 determines whether the entire trailing edge of the medium has passed the imaging position by the imaging device 119, based on the amount of tilt θ of the medium detected by the detection unit 152 (step S202). The determination unit 153 determines whether the entire trailing edge of the medium has passed the second imaging position P2 of the second imaging sensor 119d, which is located downstream from the first imaging position P1 of the first imaging sensor 119c, as the imaging position by the imaging device 119. This allows the determination unit 153 to determine whether the entire trailing edge of the medium has passed both the imaging position by the first imaging sensor 119c and the imaging position by the second imaging sensor 119d.

[0075] The determination unit 153 determines whether the amount of positional deviation in the medium discharge direction A1 between the position B1 of the trailing edge of the medium that is lagging behind, detected by the detection unit 152, and the position B2 facing the fifth medium sensor 120, is less than a predetermined distance L1. The predetermined distance L1 is set to the distance between the position of the fifth medium sensor 120 in the medium discharge direction A1 and the second imaging position P2 of the second imaging sensor 119d, which is located downstream of the first imaging position P1 of the first imaging sensor 119c (see FIG. 3). In other words, the determination unit 153 determines whether the trailing edge of the medium that is lagging behind has passed the second imaging position P2.

[0076] If the amount of positional deviation of the trailing end of the medium is less than a predetermined distance L1, the determination unit 153 determines that the entire trailing end of the medium has passed through the second imaging position P2 of the second imaging sensor 119d and has passed through the imaging position by the imaging device 119. On the other hand, if the amount of positional deviation of the trailing end of the medium is equal to or greater than the predetermined distance L1, the determination unit 153 determines that the entire trailing end of the medium has not passed through the second imaging position P2 of the second imaging sensor 119d and has not passed through the imaging position by the imaging device 119.

[0077] If it is determined that the entire trailing edge of the medium has passed the imaging position when a portion of the trailing edge of the medium passes the fifth media sensor 120, the control unit 151 controls the discharge rollers to change the rotation speed of the discharge rollers (step S203). Even if a change is made to the movement of the medium after the entire trailing edge of the medium has passed the imaging position of the imaging device 119, this does not affect the medium included in the captured medium image. When the entire trailing edge of the medium has passed the imaging position of the imaging device 119, the control unit 151 appropriately changes the rotation speed of the discharge rollers, thereby preventing distortion of the medium in the medium image and ensuring good alignment of the media loaded on the discharge tray 104. This prevents media from scattering on the discharge tray 104, eliminating the need for users to sort scattered media, and the medium discharge device 100 can improve user convenience.

[0078] For example, if it is determined that the entire trailing edge of the medium has passed the imaging position of imaging device 119 when part of the trailing edge of the medium has passed fifth medium sensor 120, control unit 151 reduces the rotation speed of the discharge rollers. This allows control unit 151 to increase the medium transport speed until the medium is imaged, and then reduce the transport speed only when the medium is being discharged. Therefore, control unit 151 can reduce the total time required for the medium reading process, while preventing the media from being discharged too quickly and causing scattering.

[0079] On the other hand, if it is determined that the entire trailing edge of the medium has not passed the imaging position when part of the trailing edge of the medium has passed the fifth medium sensor 120, the control unit 151 controls the discharge rollers so as not to change the rotation speed of the discharge rollers (step S204). If a change is made to the movement of the medium when the entire trailing edge of the medium has not passed the imaging position of the imaging device 119, this will affect the medium included in the medium image captured by the medium. If the entire trailing edge of the medium has passed the imaging position of the imaging device 119, the control unit 151 can prevent distortion of the medium from occurring in the medium image by not changing the rotation speed of each discharge roller.

[0080] In this way, the control unit 151 controls the first discharge rollers 121 and / or the second discharge rollers 122 based on the determination result by the determination unit 153. This allows the control unit 151 to properly discharge the medium while properly capturing an image of the medium.

[0081] Next, control unit 151 waits until the entire trailing edge of the medium has passed the position for imaging by imaging device 119 (step S205). Control unit 151 determines that the entire trailing edge of the medium has passed the position for imaging by imaging device 119 when a second predetermined time has elapsed since the trailing edge of the medium passed the position of fifth medium sensor 120. The second predetermined time is set to a margin time that takes into account the amount of tilt of the medium that medium ejection device 100 allows. Note that if determination unit 153 determines in step S202 that the entire trailing edge of the medium has passed the position for imaging by imaging device 119, control unit 151 determines that the entire trailing edge of the medium has already passed the position for imaging by imaging device 119.

[0082] Next, the control unit 151 combines the input images acquired from the imaging device 119 up to now to generate a medium image from the imaging device 119, and outputs the generated medium image by transmitting it to the information processing device via the interface device 132 (step S206). The medium image is an example of an image based on the input image.

[0083] Next, control unit 151 determines whether or not a medium remains on mounting table 103 based on the first medium signal received from first medium sensor 111 (step S207). If a medium remains on mounting table 103, control unit 151 returns the process to step S104 and repeats the processes of steps S104 to S109 and S201 to S207.

[0084] On the other hand, if there are no media remaining on the mounting 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 conveyance roller 117, the second conveyance roller 118, the first discharge roller 121, and the second discharge roller 122 (step S208), and the series of steps ends.

[0085] Note that the control unit 151 may determine that a medium jam has occurred and execute abnormality processing if the leading or trailing edge of the medium does not pass the position of the fourth medium sensor 116 or the position of the fifth medium sensor 120 even after a predetermined time has elapsed since the start of medium feeding. As abnormality processing, the control unit 151 stops the motor 131 and stops the feeding and discharging of the medium by the feeding roller 112, the separation roller 113, the first conveyance roller 117, the second conveyance roller 118, the first discharge roller 121, and the second discharge roller 122. As abnormality processing, the control unit 151 may notify the user by displaying information indicating that a medium jam has occurred on the display device 106 or by transmitting the information to the information processing device via the interface device 132.

[0086] As described above in detail, when a portion of the trailing edge of a medium passes a predetermined position, the medium ejection device 100 determines whether the entire trailing edge of the medium has passed the imaging position based on the amount of tilt of the medium, and if it has passed the imaging position, reduces the ejection speed. This allows the medium ejection device 100 to properly eject the medium while properly capturing an image of the medium.

[0087] Furthermore, medium ejection device 100 can easily determine whether or not the ejection speed can be changed, and can capture and eject a medium well while suppressing an increase in the processing load in the medium reading process. Furthermore, medium ejection device 100 has a compact housing with a straight path mechanism, and can capture and eject a medium well.

[0088] FIG. 9 is a flowchart showing an example of a portion of the operation of a medium reading process of a medium ejection device according to another embodiment.

[0089] The flowchart shown in Fig. 9 is executed in place of the flowchart shown in Fig. 7. The processes of steps S301 to S302, S307 to S308, and S311 to S312 in Fig. 9 are the same as the processes of steps S201 to S202, S205 to S206, and S207 to S208 in Fig. 7, and therefore descriptions thereof will be omitted. Only the processes of steps S303 to S306 and S309 to S310 will be described below.

[0090] If it is determined in step S302 that the entire trailing edge of the medium has passed the imaging position when part of the trailing edge of the medium has passed the fifth medium sensor 120, the control unit 151 controls the discharge rollers to change the rotation speed of the discharge rollers (step S303). Similar to the process in step S203, the control unit 151 reduces the rotation speed of the discharge rollers.

[0091] Next, the control unit 151 sets the image processing flag to OFF (step S304). The image processing flag is a flag that indicates whether or not image processing is to be performed on the input image.

[0092] On the other hand, if it is determined that the entire trailing edge of the medium has not passed the imaging position when part of the trailing edge of the medium has passed the fifth medium sensor 120, the control unit 151 also controls the discharge rollers to change the rotation speed of the discharge rollers (step S305). Similar to the process in step S303, the control unit 151 reduces the rotation speed of the discharge rollers.

[0093] Next, the control unit 151 sets the image processing flag to ON (step S306).

[0094] In step S309, the control unit 151 determines whether the image processing flag is set to ON or OFF (step S309). If the image processing flag is set to OFF, the control unit 151 does not execute any particular processing and causes the process to proceed to step S311.

[0095] On the other hand, if the image processing flag is set to ON, the control unit 151 executes image processing on the medium image (step S310). This allows the control unit 151 to correct distortion of the medium that occurs in the medium image while changing the medium transport speed during medium imaging. Therefore, the control unit 151 can appropriately correct distortion of the medium that occurs in the medium image while suppressing scattering of the medium on the discharge tray 104, and obtain a good medium image.

[0096] The control unit 151 performs a thinning process on the medium image. The control unit 151 performs a thinning process in the sub-scanning direction on the area in the medium image captured after the speed change, using known interpolation processes such as nearest neighbor interpolation, bilinear interpolation, and bicubic interpolation. In step S305, because the medium transport speed is reduced, the intervals between each position in the medium captured by the imaging device 119 are shortened. Therefore, in the medium image, the medium is captured in a state where it is stretched in the vertical direction (sub-scanning direction). The control unit 151 performs a thinning process so that the number of pixels in the sub-scanning direction of the area in the medium image captured after the speed change matches the number of pixels in the sub-scanning direction if the speed change is not performed. In this way, the control unit 151 can appropriately correct the stretching of the medium that occurred in the medium image and obtain a good medium image.

[0097] In this way, when it is determined that the entire trailing edge of the medium has passed the imaging position when a portion of the trailing edge of the medium has passed the fifth medium sensor 120, the control unit 151 controls the discharge rollers to change the rotation speed of the discharge rollers while performing image processing on the medium image. When it is determined that the entire trailing edge of the medium has passed the imaging position when a portion of the trailing edge of the medium has passed the fifth medium sensor 120, the control unit 151 reduces the rotation speed of the discharge rollers while performing thinning processing on the medium image. This allows the control unit 151 to properly image the medium and properly discharge it, even if the medium is transported at an angle.

[0098] As described above in detail, the medium ejection device 100 is now able to properly image and eject the medium even when the rotation speed of the ejection roller is reduced when the entire rear end of the medium has not passed the imaging position.

[0099] FIG. 10 is a flowchart showing an example of a portion of the operation of a medium reading process of a medium ejection device according to yet another embodiment.

[0100] The flowchart shown in Fig. 10 is executed in place of the flowchart shown in Fig. 7. The processes of steps S402 to S403 and S406 to S409 in Fig. 10 are the same as the processes of steps S201 to S202 and S205 to S208 in Fig. 7, and therefore descriptions thereof will be omitted. Only the processes of steps S401 and S404 to S405 will be described below.

[0101] In this embodiment, multiple first discharge rollers 121 and multiple second discharge rollers 122 are provided and arranged at intervals in the width direction A2. The multiple first discharge rollers 121 and / or multiple second discharge rollers 122 are provided so as to rotate independently to discharge the media. For example, the multiple first discharge rollers 121 and / or multiple second discharge rollers 122 are provided so as to be driven by separate motors.

[0102] In step S401, the skew determination unit 154 determines whether or not medium skew has occurred based on the amount of tilt θ of the medium detected by the detection unit 152 (step S401). For example, if the amount of tilt θ is equal to or greater than a tilt threshold, the skew determination unit 154 determines that medium skew has occurred, and if the amount of tilt θ is less than the tilt threshold, the skew determination unit 154 determines that medium skew has not occurred. The tilt threshold is preset, through prior experiments, to the minimum amount of tilt (e.g., 3°) at which a medium jam will occur if the medium tilt is not corrected.

[0103] If the skew determination unit 154 determines that no skew has occurred in the medium, it skips steps S402 to S405 and proceeds to step S406. On the other hand, if the skew determination unit 154 determines that skew has occurred in the medium, it proceeds to step S402.

[0104] If it is determined in step S403 that the entire trailing edge of the medium has passed the imaging position when part of the trailing edge of the medium has passed the fifth medium sensor 120, the control unit 151 controls the discharge rollers to change their rotation speeds (step S404). The control unit 151 controls the discharge rollers to correct the skew (tilt) of the medium. The control unit 151 corrects the skew of the medium by varying the circumferential speeds of the multiple first discharge rollers 121 and / or by varying the circumferential speeds of the multiple second discharge rollers 122. The control unit 151 sets the circumferential speeds of the discharge rollers located on the side where the medium is lagging behind so that the circumferential speed of the discharge rollers located on the side where the medium is leading is greater than the circumferential speed of the discharge rollers located on the side where the medium is leading.

[0105] 11 is a schematic diagram for explaining skew correction of a medium, showing the lower housing 101 viewed from the transport path side in a state in which the medium M2 is being transported tilted.

[0106] 11, the medium M2 is tilted so that the left end of the trailing edge is ahead and the right end is behind. In this case, the control unit 151 sets the circumferential speeds of the first discharge rollers 121 on the right side so that the circumferential speed of the first discharge rollers 121 on the left side is higher.

[0107] For example, the control unit 151 sets the peripheral speed of the discharge roller located on the side where the medium is lagging behind to a speed higher (faster) than the reference speed, and sets the peripheral speed of the discharge roller located on the side where the medium is leading to the reference speed. The control unit 151 may also set the peripheral speed of the discharge roller located on the side where the medium is lagging behind to the reference speed, and set the peripheral speed of the discharge roller located on the side where the medium is leading to a speed lower (slower) than the reference speed. The control unit 151 may also set the peripheral speed of the discharge roller located on the side where the medium is lagging behind to a speed higher (faster) than the reference speed, and set the peripheral speed of the discharge roller located on the side where the medium is leading to a speed lower (slower) than the reference speed. This causes the medium to rotate around the discharge roller located on the leading side, thereby eliminating skew of the medium. The control unit 151 also returns the peripheral speed of each discharge roller to the reference speed after a predetermined time has elapsed since starting to correct the skew of the medium.

[0108] As shown in Figure 11, when the medium M2 is transported at an angle, the positional deviation Y in the medium discharge direction A1 of the rear end of the medium M2 at the center positions D1 and D2 in the width direction A2 of the two discharge rollers is calculated using the following equation (2). Y=X tanθ (2) Here, X is the distance between the center positions D1 and D2 of the two discharge rollers in the width direction A2, and θ is the tilt angle (amount of tilt) of the trailing edge of the medium M2.

[0109] In order to make the trailing end of the lagging medium reach the center position of the lagging discharge roller in the medium discharge direction A1 after a predetermined time t, the peripheral speed v2 of the lagging discharge roller must be set as shown in the following equation (3). v2=(L2+Y / 2) / t (3) Here, L2 is the distance between the fifth medium sensor 120 and the center position of the discharge roller in the medium discharge direction A1.

[0110] On the other hand, in order to make the trailing end of the leading side reach the center position of the leading side discharge roller in the media discharge direction A1 after a predetermined time t, the peripheral speed v1 of the leading side discharge roller needs to be set as shown in the following equation (4). v1=(L2-Y / 2) / t (4)

[0111] Therefore, the medium discharge device 100 can appropriately correct the skew of the medium by setting the peripheral speed v2 of the lagging discharge roller and the peripheral speed v1 of the leading discharge roller to satisfy the following equation (5). v1 / v2=(L2-Y / 2) / (L2+Y / 2) (5)

[0112] On the other hand, if it is determined that the entire trailing edge of the medium has not passed the imaging position when part of the trailing edge of the medium has passed the fifth medium sensor 120, the control unit 151 does not correct the skew of the medium (step S405).

[0113] That is, when it is determined that medium skew has occurred, if it is determined that the entire trailing edge of the medium has passed the imaging position when a portion of the trailing edge of the medium has passed the fifth medium sensor 120, the control unit 151 controls the discharge rollers to correct the medium skew. On the other hand, when it is determined that medium skew has occurred, if it is determined that the entire trailing edge of the medium has not passed the imaging position when a portion of the trailing edge of the medium has passed the fifth medium sensor 120, the control unit 151 does not correct the medium skew. This allows the control unit 151 to properly image the medium and properly discharge it, even if the medium is transported at an angle.

[0114] Note that if the control unit 151 determines that the entire trailing edge of the medium has passed the imaging position when a portion of the trailing edge of the medium has passed the fifth media sensor 120, it may correct the skew of the medium and reduce the rotational speed of the discharge rollers. In this case, in step S404, the control unit 151 completes the correction of the skew of the medium before the discharge rollers reach the center position in the medium discharge direction A1, and then reduces the rotational speed of the discharge rollers. For example, the control unit 151 corrects the skew of the medium until the medium reaches the center position between the fifth media sensor 120 and the center position of the discharge rollers in the medium discharge direction A1, and then reduces the rotational speed of the discharge rollers. In this case, the peripheral speed v2 of the lagging discharge roller and the peripheral speed v1 of the leading discharge roller need to be set as shown in the following equations (6) and (7) instead of the above equations (3) and (4). v2=(L2 / 2+Y / 2) / t (6) v1=(L2 / 2-Y / 2) / t (7)

[0115] Therefore, the peripheral speed v2 of the lagging discharge roller and the peripheral speed v1 of the leading discharge roller are set so as to satisfy the following equation (8) instead of the above equation (5). v1 / v2=(L2-Y) / (L2+Y) (8)

[0116] Furthermore, the skew determination unit 154 may determine that no skew of the medium has occurred if the amount of positional deviation Y is less than the distance L1 between the position of the fifth medium sensor 120 and the second imaging position P2 of the second imaging sensor 119d. In this case, the control unit 151 does not correct the skew of the medium if the amount of positional deviation Y is less than the distance L1.

[0117] Furthermore, if it is determined that a medium skew has occurred and it is determined that the entire trailing edge of the medium has not passed the imaging position when a portion of the trailing edge of the medium has passed the fifth medium sensor 120, the control unit 151 may perform image processing on the medium image while correcting the medium skew. In this case, in step S404, the control unit 151 sets the image processing flag to OFF. Meanwhile, in step S405, the control unit 151 sets the image processing flag to ON while correcting the medium skew in the same manner as in step S404. In step S407, if the image processing flag is set to ON, the control unit 151 performs image processing on the medium image. The control unit 151 uses known image processing technology to perform conversion processing on the area of ​​the medium image captured after the speed change so that the medium included in the medium image becomes rectangular.

[0118] As described above in detail, the medium ejection device 100 performs skew correction when the entire trailing edge of the medium has passed the imaging position when a portion of the trailing edge of the medium has passed the predetermined position. In this case as well, the medium ejection device 100 is able to properly image the medium and eject it properly.

[0119] FIG. 12 is a flowchart showing an example of a portion of the operation of a medium reading process of a medium ejection device according to yet another embodiment.

[0120] The flowchart shown in Fig. 12 is executed in place of the flowchart shown in Fig. 6. The processing of steps S501 to S505 in Fig. 12 is the same as the processing of steps S101 to S105 in Fig. 6, and therefore a description thereof will be omitted. Only the processing of steps S506 to S508 will be described below.

[0121] In step S506, control unit 151 waits until the trailing edge of the transported medium passes both the position of second medium sensor 114 and the position of third medium sensor 115 (step S506). Control unit 151 periodically acquires a second medium signal from second medium sensor 114, and when the signal value of the second medium signal changes from a value indicating the presence of a medium to a value indicating the absence of a medium, determines that the trailing edge of the medium has passed the position of second medium sensor 114. Similarly, control unit 151 periodically acquires a third medium signal from third medium sensor 115, and when the signal value of the third medium signal changes from a value indicating the presence of a medium to a value indicating the absence of a medium, determines that the trailing edge of the medium has passed the position of third medium sensor 115.

[0122] Next, the detection unit 152 detects the amount of tilt θ of the medium based on the timing when the rear end of the transported medium passes the position of the second medium sensor 114 and the position of the third medium sensor 115 (step S507). The detection unit 152 calculates the amount of tilt θ of the medium using the following equation (9). θ=tan -1 (Y2 / W) (9) Here, Y2 is the distance traveled by the trailing edge of the medium from the time it passes one of the positions of the second medium sensor 114 and the third medium sensor 115 until it passes the other. Distance Y2 is calculated by multiplying the time elapsed from the time the trailing edge of the medium passes one of the positions of the second medium sensor 114 and the third medium sensor 115 until it passes the other by the medium transport speed. W is the distance in the width direction A2 between the second medium sensor 114 and the third medium sensor 115.

[0123] In this way, the detection unit 152 detects the amount of tilt θ of the medium based on the second medium signal from the second medium sensor 114 and the third medium signal from the third medium sensor 115. By using the second medium sensor 114 and the third medium sensor 115, which are located upstream of the imaging device 119, the detection unit 152 can detect the amount of tilt of the medium at an earlier stage.

[0124] Next, the detection unit 152 estimates the amount of positional deviation in the medium discharge direction A1 between the end position B1 of the trailing edge of the medium on the side where progress is delayed and the position B2 opposite the fifth medium sensor 120 (step S508).

[0125] The detection unit 152 identifies the left or right edge of the medium, whichever is slower at the rear end of the medium, based on the timing when the rear end of the medium passes the position of the second medium sensor 114 and the timing when the rear end of the medium passes the position of the third medium sensor 115. The detection unit 152 calculates adjacent difference values ​​in the latest input image, starting from the identified edge side, and detects the pixel whose adjacent difference value first exceeds the gradation threshold as the edge pixel corresponding to the identified edge.

[0126] The detection unit 152 calculates the horizontal distance between the detected end edge pixel and the pixel corresponding to the fifth media sensor 120 in the input image. The horizontal position of the pixel corresponding to the fifth media sensor 120 in the partial image is set in advance based on the positional relationship between the first imaging position P1 of the first imaging sensor 119c and the placement position of the fifth media sensor 120. Based on the resolution of the input image, the detection unit 152 calculates the distance x' in the width direction A2 in real space between the end position B1 of the trailing edge of the medium on the side where the medium is lagging behind and the position facing the fifth media sensor 120, which corresponds to the horizontal distance in the input image. Next, the detection unit 152 calculates (estimates) the vertical positional deviation y' in the partial image between the end position B1 of the trailing edge of the medium on the side where the medium is lagging behind and the position B2 facing the fifth media sensor 120 based on the distance x' and the tilt amount θ using the following approximate formula (10): y'≒x'·tanθ (10)

[0127] Alternatively, medium ejection device 100 may arrange multiple media sensors along the width direction A2 and identify the width direction A2 edge of the trailing end of the transported medium based on the media detection signals from each media sensor. Alternatively, medium ejection device 100 may determine that the position through which the width direction A2 edge of a medium of the maximum size supported by medium ejection device 100 passes when the medium is transported without tilting is the width direction A2 edge of the trailing end of the transported medium.

[0128] As described above in detail, the medium ejection device 100 is now able to properly image and eject the medium even when detecting the amount of tilt of the medium based on the second medium signal from the second medium sensor 114 and the third medium signal from the third medium sensor 115.

[0129] Fig. 13 is a schematic diagram for explaining a medium ejection device 200 according to another embodiment. Fig. 13 is a schematic diagram of the lower housing 101 in an open state, as viewed from the transport path side.

[0130] Medium ejection device 200 has the same components as medium ejection device 100. However, medium ejection device 200 has multiple fifth medium sensors 220 instead of fifth medium sensor 120. Multiple fifth medium sensors 220 are an example of multiple detection sensors.

[0131] The multiple fifth medium sensors 220 are disposed between the imaging device 119 and the first and second discharge rollers 121 and 122, i.e., downstream of the imaging device 119 and upstream of the first and second discharge rollers 121 and 122 in the medium discharge direction A1. The multiple fifth medium sensors 220 are also disposed at intervals in the width direction A2, which is perpendicular to the medium discharge direction. In particular, the multiple fifth medium sensors 220 are disposed between the two first discharge rollers 121 and between the two second discharge rollers 122 in the width direction A2, which is perpendicular to the medium discharge direction. Each of the multiple fifth medium sensors 220 has the same configuration and function as the fifth medium sensor 120.

[0132] Like medium ejection device 100, medium ejection device 200 executes the medium reading process shown in Fig. 6 or 12, and Fig. 7, 9, or 10. However, in step S201 in Fig. 7, step S301 in Fig. 9, or step S402 in Fig. 10, determination unit 153 waits until part of the trailing edge of the transported medium passes the position of one of the plurality of fifth medium sensors 220. When part of the trailing edge of the medium passes the position of one of the plurality of fifth medium sensors 220, determination unit 153 determines in step S202, step S302, or step S403 whether the entire trailing edge of the medium has passed the position imaged by imaging device 119.

[0133] By using multiple fifth medium sensors 220 spaced apart in the width direction A2, medium ejection device 200 can determine whether the entire trailing edge of the medium has passed the imaging position of imaging device 119 earlier than when using only one fifth medium sensor 120. Therefore, medium ejection device 200 can start changing the medium ejection speed or correcting medium skew at an earlier timing, allowing for better medium ejection.

[0134] When the medium discharge device 200 executes the medium reading process shown in FIG. 10, in step S404, the control unit 151 sets the peripheral speed of each discharge roller based on the positional relationship between the fifth medium sensor 220 that detected the trailing edge of the medium and the trailing edge of the medium. FIG. 13 shows an example in which the medium M3 is transported at an angle such that the left edge of the trailing edge leads and the right edge lags. In this case, of the multiple fifth medium sensors 220, the fifth medium sensor 220 located on the left detects the trailing edge of the medium before the fifth medium sensor 220 located on the right. The control unit 151 determines that the edge of the trailing edge of the medium that is closest to the fifth medium sensor 220 that detected the trailing edge first leads, and the edge on the opposite side lags.

[0135] For example, the control unit 151 sets the peripheral speed of the discharge roller located on the side where the medium is lagging behind to a speed higher (faster) than the reference speed, and sets the peripheral speed of the discharge roller located on the side where the medium is leading to the reference speed. The control unit 151 may also set the peripheral speed of the discharge roller located on the side where the medium is lagging behind to the reference speed, and set the peripheral speed of the discharge roller located on the side where the medium is leading to a speed lower (slower) than the reference speed. The control unit 151 may also set the peripheral speed of the discharge roller located on the side where the medium is lagging behind to a speed higher (faster) than the reference speed, and set the peripheral speed of the discharge roller located on the side where the medium is leading to a speed lower (slower) than the reference speed. This causes the medium to rotate around the discharge roller located on the leading side, thereby eliminating skew of the medium. The control unit 151 also returns the peripheral speed of each discharge roller to the reference speed after a predetermined time has elapsed since starting to correct the skew of the medium.

[0136] When the medium M3 is transported at an angle as shown in Figure 13, the distance Ya in the medium discharge direction A1 between the rear end position of the medium M3 at the center position D1 in the width direction A2 of the discharge roller located on the leading side and the position of the fifth media sensor 220 is calculated using the following equation (11). Ya=Xa·tanθ (11) Here, Xa is the distance in the width direction A2 between the center position D1 of the discharge roller located on the leading side and the position of the fifth medium sensor 220 that detected the trailing edge of the medium, and θ is the tilt angle (amount of tilt) of the trailing edge of the medium M3.

[0137] In order to make the trailing end of the leading side reach the center position of the leading side discharge roller in the media discharge direction A1 after a predetermined time t, the peripheral speed v1 of the leading side discharge roller needs to be set as shown in the following equation (12). v1=(L2-Ya) / t (12) Here, L2 is the distance between the fifth medium sensor 220 and the center position of the discharge roller in the medium discharge direction A1.

[0138] On the other hand, the distance Yb ​​in the media discharge direction A1 between the rear end position of the media M3 at the center position D2 in the width direction A2 of the discharge roller located on the lagging side and the position of the fifth media sensor 220 is calculated using the following equation (13). Yb=Xb tanθ (13) Here, Xb is the distance in the width direction A2 between the center position D2 in the width direction A2 of the discharge roller located on the lagging side and the position of the fifth medium sensor 220 that detected the trailing edge of the medium.

[0139] In order to make the trailing end of the lagging medium reach the center position of the lagging discharge roller in the medium discharge direction A1 after a predetermined time t, the peripheral speed v2 of the lagging discharge roller must be set as shown in the following equation (14). v2=(L2+Yb) / t (14)

[0140] Therefore, the medium discharge device 100 can appropriately correct the skew of the medium by setting the peripheral speed v2 of the lagging discharge roller and the peripheral speed v1 of the leading discharge roller to satisfy the following equation (15). v1 / v2=(L2-Ya) / (L2+Yb) (15)

[0141] Furthermore, when the medium ejection device 200 executes the medium reading process shown in FIG. 12, in steps S506 to S508, the medium ejection device 200 may use multiple fifth medium sensors 220 to detect the amount of tilt θ and the amount of misalignment of the trailing edge of the medium.

[0142] In this case, in step S506, the control unit 151 waits until the trailing edge of the transported medium passes the positions of both of the multiple fifth medium sensors 220. The control unit 151 periodically acquires a fifth medium signal from each fifth medium sensor 220, and determines that the trailing edge of the medium has passed the position of each fifth medium sensor 220 when the signal value of each fifth medium signal changes from a value indicating the presence of a medium to a value indicating the absence of a medium.

[0143] In step S507, the detection unit 152 detects the amount of tilt θ of the medium based on the timing when the rear end of the transported medium passes the position of each fifth medium sensor 220. The detection unit 152 calculates the amount of tilt θ of the medium using the following equation (16). θ=tan -1 (Y3 / W2) (16) Here, Y3 is the distance traveled by the trailing edge of the medium from when it passes the position of one fifth media sensor 220 until it passes the position of the other fifth media sensor 220. Distance Y3 is calculated by multiplying the time elapsed from when the trailing edge of the medium passes the position of one fifth media sensor 220 until it passes the position of the other fifth media sensor 220 by the transport speed of the medium. W2 is the distance in the width direction A2 between the two fifth media sensors 220.

[0144] In step S508, the detection unit 152 estimates the amount of positional deviation in the medium discharge direction A1 between the end position B1 of the trailing edge of the medium on the side where progress is delayed and the position B2 facing the fifth medium sensor 220.

[0145] The detection unit 152 identifies the left or right edge of the medium, whichever is lagging behind, based on the timing when the trailing edge of the medium passes the position of each fifth media sensor 220. The detection unit 152 detects edge edge pixels in the most recent input image as described with reference to FIG. 12. If the trailing edge of the medium has already passed the imaging position and no edge edge pixels are detected in the most recent input image, the detection unit 152 selects each generated input image in reverse chronological order until an edge edge pixel is detected, and detects the edge pixel from the selected input image. The detection unit 152 calculates (estimates) the vertical positional deviation y' on the partial image between the edge position B1 on the side where the trailing edge of the medium is lagging behind and the position B2 opposite the fifth media sensor 220, based on the distance x' and the tilt θ, using the approximation formula (10) described above.

[0146] In addition, the medium ejection device 100 may arrange a number of fifth medium sensors 220 in a row along the width direction A2, and identify the end of the rear end of the transported medium in the width direction A2 based on the fifth medium signal from each fifth medium sensor 220.

[0147] As described above in detail, even when the medium ejection device 200 has multiple fifth medium sensors 220, it is possible to eject the medium properly while capturing a good image of the medium.

[0148] FIG. 14 is a flowchart showing another example of the operation of the medium reading process of the medium ejection device 200.

[0149] The medium reading process shown in Fig. 14 is executed in place of the medium reading process shown in Fig. 6 or Fig. 12, and Fig. 7, Fig. 9 or Fig. 10. The processes of steps S601 to S605 in Fig. 14 are the same as the processes of steps S101 to S105 in Fig. 6, and the processes of steps S606 to S609 in Fig. 14 are the same as the processes of steps S205 to S208 in Fig. 7.

[0150] FIG. 15 is a flowchart showing an example of the operation of the detection process of the medium ejection device 200.

[0151] An example of the operation of the detection process of medium ejection device 200 will be described below with reference to the flowchart shown in Figure 15. The flow of the operation described below is executed mainly by processing circuit 150 in cooperation with each element of medium ejection device 100 based on a program stored in advance in storage device 140. The medium reading process shown in Figure 15 is executed each time a medium is transported when the medium reading process shown in Figure 14 is executed.

[0152] First, the control unit 151 waits until the trailing edge of the transported medium passes the position of one of the plurality of fifth medium sensors 220 (step S701).

[0153] Next, control unit 151 stores in storage device 140 the time at which the trailing edge of the transported medium passes the position of one of fifth medium sensors 220 (step S702).

[0154] Next, the control unit 151 executes a first correction process (step S703). In the first correction process, the control unit 151 performs skew correction on the medium by varying the peripheral speeds of the multiple discharge rollers and transporting the medium imaged by the imaging device 119. The control unit 151 performs skew correction on the medium by varying the peripheral speeds of the multiple first discharge rollers 121 and / or varying the peripheral speeds of the multiple second discharge rollers 122. The control unit 151 sets the peripheral speeds of the multiple discharge rollers so that the peripheral speed of the discharge roller located on the side of the fifth media sensor 220 that has not detected the trailing edge of the medium is higher than the peripheral speed of the discharge roller located on the side of the fifth media sensor 220 that has detected the trailing edge of the medium. In other words, the control unit 151 sets the peripheral speeds so that the peripheral speed of the discharge roller located on the side where the medium is lagging behind is higher than the peripheral speed of the discharge roller located on the side where the medium is leading. The control unit 151 sets the speed ratio of the peripheral speeds of the plurality of discharge rollers to a fixed value (for example, 2:1).

[0155] For example, the control unit 151 sets the peripheral speed of the discharge rollers located on the side where the medium is lagging behind to a speed higher than the reference speed (for example, twice the speed), and sets the peripheral speed of the discharge rollers located on the side where the medium is leading to the reference speed. Note that the control unit 151 may set the peripheral speed of the discharge rollers located on the side where the medium is lagging behind to the reference speed, and set the peripheral speed of the discharge rollers located on the side where the medium is leading to a speed lower than the reference speed (for example, 1 / 2 the speed). The control unit 151 may also set the peripheral speed of the discharge rollers located on the side where the medium is lagging behind to a speed higher than the reference speed (for example, 3 / 2 the speed), and set the peripheral speed of the discharge rollers located on the side where the medium is leading to a speed lower than the reference speed (for example, 3 / 4 the speed).

[0156] Next, the control unit 151 waits until the trailing edge of the transported medium passes the position of the other of the plurality of fifth medium sensors 220 (step S704).

[0157] Next, control unit 151 calculates the elapsed time from when the rear end of the transported medium passes the position of one of the multiple fifth medium sensors 220 to when it passes the position of the other fifth medium sensor 220 (step S705). Control unit 151 calculates the elapsed time as the time from the passing time stored in storage device 140 in step S702 to the current time.

[0158] Next, the control unit 151 determines whether the calculated elapsed time is equal to or less than a first threshold value (step S706). The first threshold value is set within the range of elapsed time calculated when the trailing edge of the medium overlaps with the discharge rollers arranged on the leading side when the trailing edge of the medium passes the positions of both fifth medium sensors 220. For example, the first threshold value is set to the elapsed time calculated when the trailing edge of the medium is located at the center position of the discharge rollers arranged on the leading side when the trailing edge of the medium passes the positions of both fifth medium sensors 220.

[0159] If the elapsed time is greater than the first threshold, the control unit 151 stops the first correction process and does not perform skew correction of the medium thereafter (step S707). The control unit 151 changes the peripheral speeds of the multiple discharge rollers to the same speed and transports the medium. If the elapsed time is greater than the first threshold, the trailing edge of the medium has already passed the position of the discharge roller arranged on the leading side, and there is a high possibility that the skew of the medium will not be corrected thereafter. In this case, by not performing skew correction of the medium, the control unit 151 can prevent damage to the medium caused by a force (load) being applied to the medium in the width direction A2.

[0160] If the elapsed time is greater than the first threshold, the control unit 151 may further determine whether the elapsed time is greater than a third threshold that is greater than the first threshold. The third threshold is set within the range of elapsed times calculated when the trailing edge of the medium overlaps with the discharge roller located on the leading side when the trailing edge of the medium passes the positions of both fifth medium sensors 220. For example, the third threshold is set to the elapsed time calculated when the trailing edge of the medium is located at the center position in the medium discharge direction A1 on the end of the discharge roller located on the leading side that is the side of the discharge roller that is lagging behind when the trailing edge of the medium passes the positions of both fifth medium sensors 220.

[0161] If the elapsed time is greater than the third threshold, the control unit 151 determines that the tilt of the medium is extremely large and that a medium transport abnormality has occurred, and executes abnormality processing. As abnormality processing, the control unit 151 stops the motor 131 and stops the ejection of the medium. As abnormality processing, the control unit 151 may also notify the user by displaying information indicating that a medium transport abnormality has occurred on the display device 106 or by sending it to the information processing device via the interface device 132. On the other hand, if the elapsed time is equal to or less than the third threshold, the control unit 151 ejects the medium without performing medium skew correction. This allows the medium ejection device 200 to more reliably prevent damage to the medium or to issue a warning to the user when the medium is too tilted.

[0162] On the other hand, if the elapsed time is equal to or less than the first threshold, the control unit 151 determines whether the elapsed time is equal to or less than a second threshold that is smaller than the first threshold (step S708). The second threshold is set within a range of elapsed time calculated when the center of rotation of the trailing end of the medium in the medium discharge direction A1 overlaps with the discharge roller arranged on the leading side when the trailing end of the medium passes the positions of both fifth medium sensors 220. In other words, the second threshold is set within a range of elapsed time calculated when the center of rotation of the trailing end of the medium overlaps with the discharge roller arranged on the leading side when the trailing end of the medium passes the positions of both fifth medium sensors 220, as viewed from the width direction A2. For example, the second threshold is set to the elapsed time calculated when the center of rotation of the trailing end of the medium in the medium discharge direction A1 is located at the center position of the discharge roller arranged on the leading side when the trailing end of the medium passes the positions of both fifth medium sensors 220.

[0163] If the elapsed time is equal to or less than the second threshold, the control unit 151 executes a second correction process (step S709). In the second correction process, similar to the first correction process, the control unit 151 performs skew correction on the medium by making the peripheral speeds of the multiple discharge rollers different from one another and transporting the medium imaged by the imaging device 119. For example, the control unit 151 executes the same correction process as the first correction process as the second correction process. That is, the control unit 151 continues the first correction process. In this case, the control unit 151 sets the peripheral speeds of the discharge rollers located on the side where the progress of the medium is lagging behind so that the peripheral speed is higher than the peripheral speed of the discharge rollers located on the side where the progress of the medium is leading. The control unit 151 sets the speed ratio of the peripheral speeds of the multiple discharge rollers to a fixed value.

[0164] If the elapsed time is equal to or less than the second threshold, the tilt of the medium is currently small enough that if the tilt continues to be corrected at the current pace, the tilt of the medium is likely to be eliminated by the time the discharge rollers finish discharging the medium. Therefore, by continuing the first correction process, the control unit 151 can eliminate the tilt of the medium and discharge the medium properly.

[0165] On the other hand, if the elapsed time is greater than the second threshold, the control unit 151 executes a third correction process (step S710). In the third correction process, similar to the first correction process, the control unit 151 performs skew correction of the medium by varying the peripheral speeds of the multiple discharge rollers and transporting the medium captured by the imaging device 119. As the third correction process, the control unit 151 executes a correction process different from the first correction process, particularly a correction process that corrects the skew of the medium to a greater extent than the first correction process. For example, the control unit 151 sets the peripheral speeds of the discharge rollers located on the side where the progress of the medium is lagging so that the peripheral speed is higher than the peripheral speed of the discharge rollers located on the leading side. The control unit 151 sets the speed ratio of the peripheral speeds of the multiple discharge rollers to a variable value, particularly a variable value corresponding to the elapsed time. The control unit 151 sets the speed ratio of the peripheral speeds of the multiple discharge rollers so that the speed difference between the discharge rollers increases as the elapsed time increases. That is, the control unit 151 sets the speed ratio of the peripheral speeds of the multiple discharge rollers so that the longer the elapsed time, the smaller the speed ratio of the peripheral speed of the discharge roller located on the side where the progress of the medium is lagging to the peripheral speed of the discharge roller located on the leading side.

[0166] If the elapsed time is greater than the second threshold, the tilt of the medium is currently large enough that even if the tilt continues to be corrected at the current pace, it is unlikely that the tilt of the medium will be completely eliminated by the time the discharge rollers finish discharging. Therefore, by increasing the degree to which the tilt of the medium is corrected, the control unit 151 can further eliminate the tilt of the medium and discharge the medium properly.

[0167] In this way, if the elapsed time from passing the position of one fifth medium sensor 220 to passing the position of the other fifth medium sensor 220 is equal to or less than the first threshold, the control unit 151 sets the speed ratio of the peripheral speeds of the multiple discharge rollers based on that elapsed time. This allows the control unit 151 to appropriately correct the tilt of the medium according to the current degree of tilt of the medium, allowing the medium to be discharged smoothly.

[0168] Next, the control unit 151 waits until the discharge of the medium is complete (step S711), and then ends the series of steps. The control unit 151 determines that the discharge of the medium is complete when a third predetermined time has elapsed since the trailing edge of the transported medium passed the positions of both of the multiple fifth medium sensors 220. The third predetermined time is set to a value obtained by adding a margin to the time required for the medium to move from the fifth medium sensor 220 to the position of the first discharge roller 121.

[0169] 16 and 17 are schematic diagrams for explaining the state of the ejected medium, showing a part of the lower housing 101 in the open state as viewed from the transport path side.

[0170] 16 and 17, line E1 indicates the extension of the trailing edge of the medium when the trailing edge of the leading side passes one (left) fifth media sensor 220, and line E2 indicates the extension of the trailing edge of the medium when the trailing edge of the lagging side passes the other fifth media sensor 220. As shown in FIGS. 16 and 17, in the width direction A2, the center of rotation R0 of the trailing edge of the medium is located on line E extending along the medium discharge direction A1. Line E is located in a position in the width direction A2 away from the center position D1 of the first discharge roller 121 on the leading side (left side) on the opposite side to the first discharge roller 121 on the lagging side (right side) by a distance W4.

[0171] On the straight line E1, attention is focused on a right triangle whose hypotenuse is a line segment connecting point R1 on the center position D1 of one of the first discharge rollers 121 to the center R0 of rotation, and another right triangle whose hypotenuse is a line segment connecting point R2 on the center position D2 of the other first discharge roller 121 to the center R0 of rotation. Due to the similarity relationship between the two right triangles, the distance W4 and the distance W3 between the center positions D1 and D2 of the two discharge rollers in the width direction A2 have the relationship expressed by the following formula (17). W4:(W3+W4)=Z1:Z2 (17) Here, Z1 is the distance between points R1 and R0 in the medium discharge direction A1. That is, Z1 is the distance required to move point R1, which is located on the center position D1 of the first discharge roller 121 on the leading side of the trailing end of the medium located on the line E1, to the same position as the center of rotation R0 in the medium discharge direction A1. On the other hand, Z2 is the distance between points R2 and R0 in the medium discharge direction A1. That is, Z2 is the distance required to move point R2, which is located on the center position D2 of the first discharge roller 121 on the lagging side of the trailing end of the medium located on the line E1, to the same position as the center of rotation R0 in the medium discharge direction A1.

[0172] The speed u1 of the leading first discharge roller 121 and the speed u2 of the lagging first discharge roller 121 are set so that the rear ends of the media are aligned (extending along the width direction A2) at the position of the rotation center R0 in the medium discharge direction A1. Therefore, the distance Z1 and the distance Z2 have the relationship shown in the following equation (18). Z1:Z2=u1:u2 (18) From equations (17) and (18), the distance W4 is calculated by the following equation (19). W4=W3×u1 / (u2-u1) (19)

[0173] The slope θ1 of the trailing edge of the leading medium (straight line E1) when the trailing edge of the leading medium passes one of the fifth medium sensors 220 is calculated using the following equation (20). θ1=tan -1 (Z0 / W5) (20) Here, Z0 is the distance in the medium discharge direction A1 between the fifth medium sensor 220 and the center of rotation R0, and W5 is the distance in the width direction A2 between the leading fifth medium sensor 220 and the center of rotation R0, and is calculated using the following equation (21). W5=W4+(W3-W2) / 2 (21)

[0174] On the other hand, the slope θ2 of the trailing edge of the medium (straight line E2) when the trailing edge of the delayed medium passes the other fifth medium sensor 220 is calculated using the following equation (22). θ2=tan -1(Z0 / W6) (22) Here, W6 is the distance in the width direction A2 between the fifth medium sensor 220 on the side where the progress is delayed and the center of rotation R0, and is calculated by the following equation (23). W6=W4+(W3+W2) / 2 (23)

[0175] The following equation (24) holds for the elapsed time T from when the trailing end of the leading side passes one of the fifth media sensors 220 until when the trailing end of the lagging side passes the other fifth media sensor 220. T=T1-T2 (24) Here, T1 is the time from when the trailing edge of the leading side passes one of the fifth medium sensors 220 until skew correction is complete, and T2 is the time from when the trailing edge of the lagging side passes the other fifth medium sensor 220 until skew correction is complete.

[0176] At time T1, the following equation (25) holds true. T1×u1=Z1 (25) Due to the similarity between a right triangle whose hypotenuse is the line segment connecting point R1 and the center of rotation R0, and a right triangle whose hypotenuse is the line segment connecting the placement position F1 of the leading fifth media sensor 220 and the center of rotation R0, the following equation (26) holds for the distance Z1. Z1:Z0=W4:W5 (26) That is, the distance Z1 has a linear relationship with the distance Z0 in the medium discharge direction A1 between the fifth medium sensor 220 and the center of rotation R0.

[0177] On the other hand, for time T2, the following equation (27) holds. T2×u2=Z4 (27) Here, Z4 is the distance required to move point R4 on center position D2 of the first discharge roller 121 on the delayed side of the trailing edge of the medium located on line E2 to the same position as the rotation center R0 in the medium discharge direction A1. Due to the similarity between a right triangle whose hypotenuse is the line segment connecting point R4 and rotation center R0, and a right triangle whose hypotenuse is the line segment connecting position F2 of the fifth medium sensor 220 on the delayed side and rotation center R0, the following equation (28) holds for distance Z4. Z4:Z0=(W3+W4):W6 (28) That is, the distance Z4 has a linear relationship with the distance Z0 in the medium discharge direction A1 between the fifth medium sensor 220 and the center of rotation R0.

[0178] From equations (24) to (28), it is clear that the elapsed time T between the trailing edge of the medium passing the two fifth medium sensors 220 is proportional to the distance Z0 in the medium discharge direction A1 between the fifth medium sensor 220 and the center of rotation R0. Furthermore, the distance Z0 in the medium discharge direction A1 between the fifth medium sensor 220 and the center of rotation R0 is calculated uniquely from the elapsed time T between the trailing edge of the leading medium passing the two fifth medium sensors 220.

[0179] As described above, the second threshold value is set to the elapsed time calculated when, for example, the center of rotation of the trailing edge of the medium in the medium discharge direction A1 is located at the center position of the discharge roller located on the leading side when the trailing edge of the medium passes the positions of both fifth medium sensors 220. In other words, the second threshold value is set to the elapsed time T when the distance Z0 in the medium discharge direction A1 between the fifth medium sensor 220 and the center of rotation R0 matches the distance L2 between the fifth medium sensor 220 in the medium discharge direction A1 and the center position of the discharge roller.

[0180] When the elapsed time T is equal to or less than the second threshold, the center of rotation R0 of the trailing edge of the medium is located upstream of the center position of the discharge rollers, as shown in FIG. 16, and if the speed ratio of the discharge rollers remains at its current setting, it is highly likely that the discharge rollers will completely eliminate the skew of the medium. On the other hand, when the elapsed time is greater than the second threshold, the center of rotation R0 of the trailing edge of the medium is located downstream of the center position of the discharge rollers, as shown in FIG. 17. In this case, if the speed ratio of the discharge rollers remains at its current setting, it is highly likely that the trailing edge of the medium will pass the discharge rollers before the discharge rollers completely eliminate the skew of the medium, and the discharge rollers will not completely eliminate the skew of the medium. Therefore, by changing the method of correcting the skew of the medium depending on whether the elapsed time T is equal to or less than the second threshold, the medium discharge device 100 can appropriately correct the skew of the medium according to the current inclination of the medium and successfully discharge the medium.

[0181] The tilts θ1 and θ2 of the trailing edge of the medium when it passes each fifth medium sensor 220 are calculated using the above equations (20) and (22) from the distance Z0 calculated from the elapsed time T. The tilt θ0 corrected by the time the trailing edge of the medium passes both fifth medium sensors 220 is calculated using the following equation (29). θ0=θ1-θ2 (29)

[0182] Figure 18(A) is an example of a graph 1800 showing the relationship between the elapsed time T between the trailing edge of the medium passing two fifth media sensors 220 and the distance Z0 in the media discharge direction A1 between the fifth media sensor 220 and the center of rotation R0.

[0183] In Figure 18(A), the horizontal axis represents elapsed time T [sec], and the vertical axis represents distance Z0 [mm]. Figure 18(A) shows an example in which the distance W2 between the two fifth medium sensors 220 is 45 [mm], the distance W3 between the center positions D1 and D2 of the two discharge rollers is 70 [mm], and the peripheral speeds u1 and u2 of the discharge rollers are 200 and 400 [mm / sec]. As shown in graph 1800, there is a proportional relationship between the elapsed time T for the trailing edge of the medium to pass the two fifth medium sensors 220 and the distance Z0 in the medium discharge direction A1 between the fifth medium sensor 220 and the center of rotation R0.

[0184] Therefore, the medium ejection device 100 can accurately identify the position of the center of rotation of the trailing edge of the medium from the elapsed time T between the trailing edge of the medium passing the two fifth medium sensors 220. The medium ejection device 100 can easily and accurately calculate the elapsed time T between the trailing edge of the medium passing the two fifth medium sensors 220, and therefore can easily and accurately identify the position of the center of rotation of the trailing edge of the medium. From graph 1800, when the distance L2 in the medium ejection direction A1 between the fifth medium sensor 220 and the center position of the ejection roller is 8 [mm], it is preferable to set the second threshold to 0.012 [sec].

[0185] FIG. 18B is an example of a graph 1810 showing the relationship between the elapsed time T between the trailing edge of the medium passing the two fifth medium sensors 220 and the time from the start of skew correction to the completion of skew correction.

[0186] In FIG. 18(B), the horizontal axis represents elapsed time T [sec], and the vertical axis represents the time [sec] from the start of skew correction to its completion. FIG. 18(B) shows an example under the same conditions as FIG. 18(A). Note that FIG. 18(B) shows an example in which skew correction is performed while the peripheral speeds u1 and u2 of the discharge rollers are set to 200 and 400 [mm / sec], respectively, regardless of the length of elapsed time T. As shown in graph 1810, when the speed ratio between the peripheral speeds u1 and u2 of the discharge rollers is constant, the elapsed time T between the trailing edge of the medium passing the two fifth media sensors 220 and the time until skew correction is completed are proportional to each other.

[0187] Therefore, the medium ejection device 100 can accurately determine the time until skew correction is complete from the elapsed time T between the trailing edge of the medium passing the two fifth medium sensors 220. Because the medium ejection device 100 can easily and accurately calculate the elapsed time T between the trailing edge of the medium passing the two fifth medium sensors 220, it can easily and accurately determine the time until skew correction is complete.

[0188] FIG. 19A is an example of a graph 1900 showing the relationship between the time T that elapses between the trailing edge of the medium passing two fifth medium sensors 220 and the tilt θ1 of the medium before skew correction is performed.

[0189] In Figure 19(A), the horizontal axis represents the elapsed time T [sec] between the trailing edge of the medium passing the two fifth media sensors 220, and the vertical axis represents the tilt θ1 [deg] of the medium before skew correction is performed. Figure 19(A) shows an example under the same conditions as Figure 18(A). As shown in graph 1900, there is a proportional relationship between the elapsed time T between the trailing edge of the medium passing the two fifth media sensors 220 and the tilt θ1 of the medium before skew correction is performed.

[0190] Therefore, the medium ejection device 100 can accurately determine the tilt θ1 of the medium before skew correction is performed from the elapsed time T between the trailing edge of the medium passing the two fifth medium sensors 220. Because the medium ejection device 100 can easily and accurately calculate the elapsed time T between the trailing edge of the medium passing the two fifth medium sensors 220, it can easily and accurately determine the tilt θ1 of the medium before skew correction is performed.

[0191] FIG. 19B is an example of a graph 1900 showing the relationship between the tilt θ0 corrected until the trailing edge of the medium passes both fifth medium sensors 220 and the tilt θ1 of the medium before skew correction is performed.

[0192] In Figure 19(B), the horizontal axis represents the tilt θ0 [deg] corrected by the time the trailing edge of the medium passes both fifth media sensors 220, and the vertical axis represents the tilt θ1 [deg] of the medium before skew correction is performed. Figure 19(B) shows an example under the same conditions as Figure 18(A). As shown in graph 1910, there is a proportional relationship between the tilt θ0 corrected by the time the trailing edge of the medium passes both fifth media sensors 220 and the tilt θ1 of the medium before skew correction is performed.

[0193] Figure 20(A) is an example of a graph 2000 showing the relationship between the elapsed time T between the trailing edge of the medium passing two fifth media sensors 220 and the slope θ0 corrected until the trailing edge of the medium passes both fifth media sensors 220.

[0194] In Figure 20(A), the horizontal axis represents the elapsed time T [sec] between the trailing edge of the medium passing the two fifth medium sensors 220, and the vertical axis represents the tilt θ0 [deg] that is corrected until the trailing edge of the medium passes both fifth medium sensors 220. Figure 20(A) shows an example under the same conditions as Figure 18(A). As shown in graph 2000, there is a proportional relationship between the elapsed time T between the trailing edge of the medium passing the two fifth medium sensors 220 and the tilt θ0 that is corrected until the trailing edge of the medium passes both fifth medium sensors 220.

[0195] Therefore, the medium ejection device 100 can accurately determine, from the elapsed time T between the trailing edge of the medium passing the two fifth medium sensors 220, the tilt θ0 that is corrected until the trailing edge of the medium passes both fifth medium sensors 220. Because the medium ejection device 100 can easily and accurately calculate the elapsed time T between the trailing edge of the medium passing the two fifth medium sensors 220, it can easily and accurately determine the tilt θ0 that is corrected until the trailing edge of the medium passes both fifth medium sensors 220.

[0196] Similarly, there is a proportional relationship between the elapsed time T between the trailing edge of the medium passing the two fifth medium sensors 220 and the tilt θ2 of the medium when the trailing edge of the medium passes both fifth medium sensors 220. Therefore, the medium ejection device 100 can correctly determine the tilt θ2 of the medium when the trailing edge of the medium passes both fifth medium sensors 220 from the elapsed time T between the trailing edge of the medium passing the two fifth medium sensors 220. Because the medium ejection device 100 can easily and accurately calculate the elapsed time T between the trailing edge of the medium passing the two fifth medium sensors 220, it can easily and accurately determine the tilt θ2 of the medium when the trailing edge of the medium passes both fifth medium sensors 220.

[0197] As described above, if the elapsed time is greater than the second threshold, the center of rotation R0 of the trailing edge of the medium is located downstream of the center position of the discharge rollers, and if the speed ratio of the discharge rollers remains at its current setting, it is highly likely that the discharge rollers will not be able to completely eliminate the skew of the medium. For the discharge rollers to eliminate the skew of the medium, points R3 and R4 on the trailing edge of the medium (straight line E2) shown in FIG. 17 must simultaneously reach the center position of the first discharge roller 121 in the medium discharge direction A1. Point R3 is a point on the center position D1 of the leading first discharge roller 121, and point R4 is a point on the center position D2 of the lagging first discharge roller 121. To achieve this, as shown in FIG. 17, once the trailing edge of the medium passes the positions of both fifth media sensors 220, the center of rotation of the trailing edge of the medium must be reset to point R5, where the trailing edge of the medium (straight line E2) intersects with the center position of the discharge roller in the medium discharge direction A1.

[0198] If the elapsed time is greater than the second threshold, when the rear end of the medium passes the positions of both fifth media sensors 220, the speed ratio between the speed u1 of the leading first discharge roller 121 and the speed u2 of the lagging first discharge roller 121 is reset as shown in the following equation (30). u1:u2=Z5:Z6 (30) Here, Z5 is the distance on the line E2 between point R3 at the center position D1 in the width direction A2 of the leading first discharge roller 121 and the center position in the medium discharge direction A1 of that first discharge roller 121. Z6 is the distance on the line E2 between point R4 at the center position D2 in the width direction A2 of the lagging first discharge roller 121 and the center position in the medium discharge direction A1 of that first discharge roller 121.

[0199] On the straight line E2, attention is focused on a right triangle whose hypotenuse is a line segment connecting points R3 and R5 on the center position D1 of one of the first discharge rollers 121, and a right triangle whose hypotenuse is a line segment connecting points R4 and R5 on the center position D2 of the other first discharge roller 121. Due to the similarity relationship between the two right triangles, the distances Z5 and Z6 have the relationship of the following equation (31). Z5:Z6=(W4-Z7):(W3+W4-Z7) (31) Here, Z7 is the distance in the width direction A2 between point R5 and line E. Z7 is calculated by the following formula (32) by focusing on a right triangle whose hypotenuse is the line segment connecting point R5 and the original rotation center R0. Z7=(Z0-L2) / tan(θ2) (32)

[0200] In this way, when the elapsed time is greater than the second threshold value, the speed ratio of the peripheral speeds of the multiple discharge rollers is set to a variable value according to the amount of skew of the medium (θ2) rather than a fixed value, so that the discharge rollers completely eliminate the skew of the medium and the medium is discharged smoothly.

[0201] FIG. 20B is an example of a graph 2010 showing the relationship between the elapsed time T between the trailing edge of the medium passing two fifth medium sensors 220 and the speed ratio of the peripheral speeds of multiple discharge rollers.

[0202] In FIG. 20(B), the horizontal axis represents elapsed time T [sec], and the vertical axis represents the speed ratio of the peripheral speeds of the multiple first discharge rollers 121 (the ratio of the speed u1 of the leading first discharge roller 121 to the speed u2 of the lagging first discharge roller 121). FIG. 20(B) shows an example under the same conditions as FIG. 18(A). As shown in graph 2010, the speed ratio is smaller than 1, and decreases as the elapsed time T increases. Therefore, the longer the elapsed time T between the rear end of the medium passing the two fifth media sensors 220, the greater the speed difference between the multiple first discharge rollers 121, and the more rapidly the skew of the medium is corrected.

[0203] As described above, the first threshold is set to the elapsed time calculated when, for example, the trailing edge of the medium passes both fifth media sensors 220 and is located at the center position of the leading discharge roller. That is, the first threshold is set to the elapsed time T when point R5, the new center of rotation, is located at the center position of the leading first discharge roller 121. That is, the first threshold is set to the elapsed time T when distance Z7 in the width direction A2 between point R5, the new center of rotation, and line E matches distance W4 in the width direction A2 between center position D1 in the width direction A2 of the leading first discharge roller 121 and line E. If the elapsed time is greater than the first threshold, the trailing edge of the medium has already passed the center position of the leading first discharge roller 121, and it is highly likely that the skew of the medium will not be corrected thereafter. In this case, the medium discharge device 100 can prevent damage to the medium caused by a force (load) applied to the medium in the width direction A2 by not correcting the skew of the medium.

[0204] The third threshold is set to the elapsed time calculated when, for example, the trailing edge of the medium passes both fifth medium sensors 220 and is located at the center of the leading discharge roller in the medium discharge direction A1, on the edge of the leading discharge roller that is closest to the lagging discharge roller. That is, the third threshold is set to the elapsed time T when point R5, the new center of rotation, is located at the edge of the leading first discharge roller 121 (the edge of the lagging first discharge roller 121). That is, the third threshold is set to the elapsed time T when distance Z7 in the width direction A2 between point R5, the new center of rotation, and line E matches the distance in the width direction A2 between the edge of the leading first discharge roller 121 closest to the center in the width direction A2 and line E. If the elapsed time is greater than the third threshold, the medium is likely to be extremely tilted. In this case, the medium discharge device 200 can more reliably prevent damage to the medium or issue a warning to the user by performing abnormality processing.

[0205] FIG. 21 is an example of a graph 2100 showing the relationship between the elapsed time T between the trailing edge of the medium passing the two fifth media sensors 220 and the distance Z7 in the width direction A2 between point R5 and the line E at the time when the trailing edge of the medium has passed both fifth media sensors 220.

[0206] In Figure 21, the horizontal axis represents elapsed time T [sec], and the vertical axis represents distance Z7 [mm]. Figure 21 shows an example with the same conditions as Figure 18(A). Figure 21 also shows an example where the width of each discharge roller is 20 [mm]. As shown in graph 2100, the longer the elapsed time T between the trailing edge of the medium passing the two fifth media sensors 220, the longer the distance Z7.

[0207] 21, when distance Z7 coincides with distance W4 (70 mm) between the center position in the width direction A2 of the leading first discharge roller 121 and line E, the elapsed time T is 0.026 seconds. In this example, the medium discharge device 200 does not perform skew correction of the medium if the elapsed time T is greater than 0.026 seconds. Furthermore, when distance Z7 coincides with the distance in the width direction A2 between the center end position in the width direction A2 of the leading first discharge roller 121 and line E (70 + 20 / 2 = 80 mm), the elapsed time T is 0.032 seconds. In this example, the medium discharge device 200 performs abnormality processing if the elapsed time T is greater than 0.032 seconds.

[0208] As described above in detail, the medium ejection device 200 determines whether to perform skew correction based on the elapsed time from when the trailing edge of the medium passes one of the plurality of fifth medium sensors 220 until it passes the other fifth medium sensor 220. This allows the medium ejection device 200 to appropriately determine whether to perform skew correction depending on the current state of the medium's tilt. This allows the medium ejection device 200 to properly eject the medium.

[0209] Furthermore, the medium ejection device 200 can easily determine whether to perform skew correction by using the elapsed time between the trailing edge of the medium passing the two fifth medium sensors 220, thereby suppressing an increase in the processing load during the medium reading process. Furthermore, the medium ejection device 200 has a compact housing with a straight path mechanism, yet is able to appropriately correct the skew of the medium. In particular, the medium ejection device 200 can appropriately correct the skew of the medium even when the distance between the fifth medium sensor 220, which is located downstream of the imaging device 119, and the first ejection roller 121 is small.

[0210] If the elapsed time is equal to or less than the first threshold value and greater than the second threshold value, the control unit 151 may perform skew correction of the medium by setting the speed ratio of the peripheral speeds of the multiple discharge rollers so that skew is not eliminated when the medium is discharged from the multiple discharge rollers. In this case, in step S710 of Fig. 15, as the third correction process, the control unit 151 performs skew correction of the medium by setting the speed ratio of the peripheral speeds of the multiple discharge rollers so that skew is not eliminated when the medium is discharged from the multiple discharge rollers.

[0211] For example, the control unit 151 does not change the speed ratio of the peripheral speeds of the multiple discharge rollers from the speed ratio in the first correction process. Instead, the control unit 151 stops correcting the skew of the medium when it becomes impossible to correct the skew of the medium while the medium is being discharged. The control unit 151 calculates the distance Z5 on the line E2 between point R3 on the center position D1 of the leading first discharge roller 121 in the width direction A2 and the center position of that first discharge roller 121 in the medium discharge direction A1 using the following equation (33) (see FIG. 17). The control unit 151 performs skew correction of the medium for a time calculated by dividing distance Z5 by the speed u1 of the leading first discharge roller 121, and then stops correcting the skew of the medium. Z5=(W4-Z7)·tan(θ2) (33)

[0212] Alternatively, the control unit 151 calculates the distance Z6 on the line E2 between the point R4 on the center position D2 in the width direction A2 of the first discharge roller 121 on the delayed side and the center position in the medium discharge direction A1 of that first discharge roller 121 using the following equation (34) (see FIG. 17). The control unit 151 performs skew correction of the medium for a time calculated by dividing the distance Z5 by the speed u2 of the first discharge roller 121 on the delayed side, and then stops skew correction of the medium. Z6=(W3+W4-Z7)·tan(θ2) (34)

[0213] In this case, the speed of the discharge rollers changes while the medium is being discharged, thereby preventing the medium from being subjected to a load. Therefore, the medium discharge device 100 can correct the skew of the medium as much as possible and discharge the medium smoothly while preventing the medium from being subjected to a load that would cause wrinkles.

[0214] On the other hand, if the elapsed time is equal to or less than the second threshold, the control unit 151 performs skew correction on the medium by setting the speed ratio of the circumferential velocities of the multiple discharge rollers so that skew is eliminated when the medium is discharged from the multiple discharge rollers. In this case, the control unit 151 sets the speed ratio of the circumferential velocities of the multiple discharge rollers to a fixed value as the second correction process in step S709 of FIG. 15 . Note that in this case, the control unit 151 may also set the speed ratio of the circumferential velocities of the multiple discharge rollers to a variable value depending on the elapsed time as the second correction process, as in the original third correction process.

[0215] As a result, if the medium ejection device 200 can completely eliminate the tilt of the medium, it can reliably correct the skew of the medium and eject the medium properly.

[0216] In this way, if the elapsed time is equal to or less than the second threshold, the control unit 151 continues correcting the skew of the medium until the skew of the medium is eliminated, but if the elapsed time is greater than the second threshold, the control unit 151 ends correcting the skew of the medium before the skew of the medium is eliminated. This allows the medium ejection device 200 to appropriately correct the skew of the medium while suppressing the occurrence of wrinkles in the medium.

[0217] Furthermore, the control unit 151 may stop skew correction of the medium if the elapsed time is equal to or less than the second threshold. In this case, in step S709 of FIG. 15, the control unit 151 determines that the skew of the medium has been sufficiently eliminated, stops the first correction process, and does not perform skew correction of the medium. This prevents load from being applied to the medium due to changes in the speed of the discharge rollers while the medium is being discharged. Therefore, the medium discharge device 100 can prevent wrinkles from being generated due to load being applied to the medium, and can discharge the medium smoothly.

[0218] Furthermore, the processing of step S703 may be omitted, and the control unit 151 may not correct the skew of the medium until the trailing edge of the medium passes both of the plurality of fifth medium sensors 220.

[0219] Fig. 22 is a schematic diagram for explaining the state of the ejected medium when the processing of step S703 is omitted. Fig. 22 is a schematic diagram of a part of the lower housing 101 in the open state, viewed from the transport path side.

[0220] 22, line E2 indicates the extension of the trailing edge of the medium when the trailing edge of the medium has passed both fifth medium sensors 220. Line E is set at the same position as line E shown in Figure 16. Line E is set at the position in the width direction A2 of the center of rotation R0 of the trailing edge of the medium when the peripheral speeds of the multiple discharge rollers are set to have the speed ratio set in the second correction process of step S709.

[0221] The slope θ2 of the trailing edge of the medium (straight line E2) when the trailing edge of the medium passes both fifth medium sensors 220 is calculated using the following equation (35). θ2=tan -1 (Z8 / W2) (35) Here, W2 is the distance between the two fifth medium sensors 220. Z8 is the distance traveled in the medium discharge direction A1 at the position of the leading fifth medium sensor 220 from when the trailing edge of the medium passes the position of the leading fifth medium sensor 220 until when it passes the position of the lagging fifth medium sensor 220. Distance Z8 is calculated using the following equation (36): Z8=u2×T (36) Here, u2 is the speed of each first discharge roller 121. T is the time from when the trailing edge of the leading side passes one of the fifth medium sensors 220 until when the trailing edge of the lagging side passes the other fifth medium sensor 220.

[0222] The distance Z0 between the fifth medium sensor 220 and the center of rotation R0 in the medium discharge direction A1 is calculated by the following equation (37). Z0=W6×tan(θ2) (37) Here, W6 is the distance in the width direction A2 between the fifth medium sensor 220 on the delayed side and the center of rotation R0, and is calculated using the above-mentioned equation (23).

[0223] From equations (35) to (37), it is clear that the elapsed time T between the trailing edge of the medium passing the two fifth medium sensors 220 is proportional to the distance Z0 in the medium discharge direction A1 between the fifth medium sensor 220 and the center of rotation R0. Furthermore, the distance Z0 in the medium discharge direction A1 between the fifth medium sensor 220 and the center of rotation R0 is calculated uniquely from the elapsed time T between the trailing edge of the leading medium passing the two fifth medium sensors 220.

[0224] The first threshold, second threshold, third threshold, and speed ratio of each first discharge roller 121 in the third correction process are set in the same manner as the first threshold, second threshold, third threshold, and speed ratio when the process of step S703 is executed. This allows the medium discharge device 200 to appropriately correct the skew of the medium and discharge the medium successfully, even when the skew correction of the medium is not executed until the trailing edge of the medium passes both of the fifth medium sensors 220.

[0225] 23 is a diagram showing a schematic configuration of a processing circuit 350 in a medium ejection device according to another embodiment. The processing circuit 350 is used in place of the processing circuit 150 of the medium ejection device 100, and executes media reading processing and the like in place of the processing circuit 150. The processing circuit 350 includes a control circuit 351, a detection circuit 352, a determination circuit 353, and a skew determination circuit 354. Note that each of these components may be configured as an independent integrated circuit, microprocessor, firmware, or the like.

[0226] The control circuit 351 is an example of a control unit and has the same functions as the control unit 151. The control circuit 351 receives an operation signal from the operation device 105 or the interface device 132, a first medium signal from the first medium sensor 111, a fourth medium signal from the fourth medium sensor 116, and a fifth medium signal from the fifth medium sensor 220. The control circuit 351 controls the motor 131 based on the received information, and also acquires an input image from the imaging device 119 and stores it in the storage device 140. The control circuit 351 generates a partial image from the input image and stores it in the storage device 140, and also generates a medium image from the input image and outputs it to the interface device 132. The control circuit 351 also reads from the storage device 140 a determination result as to whether the entire trailing edge of the medium has passed the imaging position and / or a determination result of the skew of the medium, and controls the motor 131 to control the discharge rollers based on the read determination result.

[0227] Detection circuit 352 is an example of a detection unit, and has the same functions as detection unit 152. Detection circuit 352 receives a second medium signal from second medium sensor 114, a third medium signal from third medium sensor 115, and a fourth medium signal from fourth medium sensor 116, and also reads a partial image or an input image from storage device 140. Detection circuit 352 detects the amount of tilt and misalignment of the medium from the acquired information, and stores the detection results in storage device 140.

[0228] Determination circuit 353 is an example of a determination unit, and has the same function as determination unit 153. Determination circuit 353 receives a fifth medium signal from fifth medium sensor 220, and reads out the detection results of the amount of tilt and misalignment of the medium from storage device 140. Based on the acquired information, determination circuit 353 determines whether the entire rear end of the medium has passed the imaging position, and stores the determination result in storage device 140.

[0229] The skew determination circuit 354 is an example of a skew determination unit, and has the same function as the skew determination unit 154. The skew determination circuit 354 reads out the detection results of the tilt amount and misalignment amount of the medium from the storage device 140, determines whether or not skew of the medium has occurred based on the read detection results, and stores the determination result in the storage device 140.

[0230] As described above in detail, the medium ejection device is now able to eject the medium well while capturing a good image of the medium, even when using the processing circuit 350. [Explanation of symbols]

[0231] 100, 200 medium discharge device, 114 second medium sensor, 115 third medium sensor, 119 imaging device, 119c first imaging sensor, 119d second imaging sensor, 120, 220 fifth medium sensor, 121 first discharge roller, 122 second discharge roller, 151 control unit, 152 detection unit, 153 determination unit, 154 skew determination unit

Claims

1. An imaging unit; a plurality of discharge rollers disposed downstream of the imaging unit in a medium discharge direction and spaced apart in a direction perpendicular to the medium discharge direction; a plurality of detection sensors disposed at intervals in a direction perpendicular to the medium discharge direction between the imaging unit and the plurality of discharge rollers; a control unit that performs skew correction of the medium by making the peripheral speeds of the plurality of discharge rollers different from one another and transporting the medium imaged by the imaging unit, the control unit performs the skew correction when an elapsed time from when the trailing edge of the medium passes one of the plurality of detection sensors until when the trailing edge of the medium passes the other of the detection sensors is equal to or less than a first threshold value, and does not perform the skew correction when the elapsed time is greater than the first threshold value. A medium ejection device characterized by:

2. 2. The medium ejection device according to claim 1, wherein the control unit sets a speed ratio of the peripheral speeds of the plurality of ejection rollers so that skew is eliminated when the medium is ejected from the plurality of ejection rollers when the elapsed time is equal to or less than a second threshold value that is smaller than the first threshold value.

3. The medium ejection device according to claim 1 , wherein the control unit sets a speed ratio of the peripheral speeds of the plurality of ejection rollers based on the elapsed time when the elapsed time is equal to or less than the first threshold value.

4. The control unit sets the speed ratio of the peripheral speed of the discharge roller on the leading side to the peripheral speed of the discharge roller on the side where the progress of the medium is delayed, among the multiple discharge rollers, to a fixed value set before transporting the medium.

5. The control unit sets the speed ratio of the peripheral speed of the discharge roller on the side where the progress of the medium is delayed to the peripheral speed of the discharge roller on the leading side to a variable value.

6. A medium discharge device as described in any one of claims 1 to 5, wherein the control unit performs the skew correction by setting the speed ratio of the peripheral speeds of the multiple discharge rollers so that skew is not eliminated when the medium is discharged from the multiple discharge rollers when the elapsed time is less than the first threshold value and greater than a second threshold value that is smaller than the first threshold value.

7. The control unit sets the speed ratio of the peripheral speed of the leading discharge roller of the plurality of discharge rollers on which the progress of the medium is delayed to the peripheral speed of the leading discharge roller on which the progress of the medium is delayed to a fixed value set before transporting the medium when the elapsed time is equal to or less than a second threshold value smaller than the first threshold value, and sets the speed ratio of the peripheral speed of the leading discharge roller of the plurality of discharge rollers on which the progress of the medium is delayed to a variable value when the elapsed time is smaller than the first threshold value and greater than the second threshold value.

8. A method for controlling a medium ejection device, comprising: and performing skew correction of the medium by conveying the medium imaged by the imaging unit by varying the peripheral speeds of a plurality of discharge rollers that are disposed downstream of the imaging unit in the medium discharge direction and spaced apart in a direction perpendicular to the medium discharge direction, In performing the skew correction, if the elapsed time from when the trailing edge of the medium passes one of a plurality of detection sensors arranged at intervals in a direction perpendicular to the medium discharge direction between the imaging unit and the plurality of discharge rollers until when the trailing edge of the medium passes another detection sensor is equal to or less than a first threshold value, the skew correction is performed, and if the elapsed time is greater than the first threshold value, the skew correction is not performed. A control method comprising:

9. A control program for a medium ejection device having an imaging unit, a plurality of ejection rollers arranged downstream of the imaging unit in a medium ejection direction and spaced apart in a direction perpendicular to the medium ejection direction, and a plurality of detection sensors arranged between the imaging unit and the plurality of ejection rollers and spaced apart in a direction perpendicular to the medium ejection direction, causing the medium ejection device to perform skew correction of the medium by conveying the medium imaged by the imaging unit while making the peripheral speeds of the plurality of ejection rollers different from one another; In performing the skew correction, if the elapsed time from when the trailing edge of the medium passes one of a plurality of detection sensors arranged at intervals in a direction perpendicular to the medium discharge direction between the imaging unit and the plurality of discharge rollers until when the trailing edge of the medium passes another detection sensor is equal to or less than a first threshold value, the skew correction is performed, and if the elapsed time is greater than the first threshold value, the skew correction is not performed. A control program comprising:

Images