Media transport device, media transport method, and control program

Abstract

To provide a medium transport device which can determine whether or not a medium should be subject to abnormality control with higher accuracy.SOLUTION: A medium transport device includes: a pick roller; first and second lifting sensors which are respectively disposed at one side and the other side relative to the pick roller at the downstream side relative to the pick roller and detect lifting of the medium; first and second detection sensors which are respectively disposed at the same sides as the first and second lifting sensors relative to the pick roller and detect the medium; a determination unit which determines whether or not the medium is a predetermined medium based on detection results of lifting of the medium; and a control unit which executes abnormality control if it is determined that the medium is the predetermined medium. The determination unit makes the medium less likely to be determined to be the predetermined medium based on the detection result of lifting of the medium by the first lifting sensor if the one side of the medium precedes the other side.SELECTED DRAWING: Figure 1

Description

Technical Field

[0006] ,

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

Background Art

[0002] Generally, a medium conveyance device such as a scanner that conveys and images a medium sequentially separates and conveys a plurality of media stacked one on top of another on a mounting table. However, when a plurality of media are stapled together or the like, there is a possibility that the media will be damaged when separating these media. Therefore, in a medium conveyance device, it is required to appropriately detect such stapled media and execute abnormal control such as stopping the conveyance.

[0003] Patent Document 1 describes an image reading device having first to third sheet detection means arranged in a conveyance path of a medium to detect the medium, and determining whether the medium is a stapled medium based on a time difference in the time when each sheet detection means detects the medium. Since a stapled medium skews during separation, it is possible to determine whether the medium is a stapled medium based on the difference in detection time caused by the skew of the medium.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a medium conveyance device, it is required to highly accurately determine whether a medium for which abnormal control should be executed, such as a stapled medium, is present.

[0006] An object of the present invention is to provide a medium conveyance device, a control method, and a control program that enable more highly accurate determination of whether a medium for which abnormal control should be executed is present. [Means for solving the problem]

[0007] The media transport device according to an embodiment of the present invention includes a pick roller for feeding media, a first lift sensor positioned downstream of the upstream end of the nip width of the pick roller and on one side of the pick roller in the direction of media transport, for detecting the lifting of the media, a second lift sensor positioned downstream of the upstream end of the nip width of the pick roller and on the other side of the pick roller in the direction of transport, for detecting the lifting of the media, a first detection sensor positioned on the same side of the pick roller as the first lift sensor for detecting the media, a second detection sensor positioned on the same side of the pick roller as the second lift sensor for detecting the media, and a first or second lift sensor If the height of the media's levitation detected by this method is greater than or equal to the threshold, The medium is the specified medium. and The system includes a determination unit that makes a determination, and a control unit that performs abnormality control when it is determined that the medium is a predetermined medium. The determination unit detects, using the first and second detection sensors, that the side of the medium closest to the first detection sensor is ahead of the side closest to the second detection sensor, and then detects the first floating sensor Increase the threshold for this. It is characterized by the following:

[0008] The media conveying method according to an embodiment of the present invention involves feeding the media with a pick roller, and downstream of the upstream end of the nip width of the pick roller, media A first lift sensor positioned on one side of the pick roller in the direction of transport detects the lifting of the medium, a second lift sensor positioned downstream of the upstream end of the nip width of the pick roller, on the other side of the pick roller in the direction of transport detects the lifting of the medium, a first detection sensor positioned on the same side of the pick roller as the first lift sensor detects the medium, a second detection sensor positioned on the same side of the pick roller as the second lift sensor detects the medium, and the first or second lift sensor If the height of the media's levitation detected by this method is greater than or equal to the threshold, The medium is the specified medium. andThis includes making a determination, and if it is determined that the medium is a predetermined medium, executing abnormality control, and in making the determination, if the first and second detection sensors detect that the side of the medium where the first detection sensor is located is ahead of the side where the second detection sensor is located, the first floating sensor Increase the threshold for this. It is characterized by the following:

[0009] A control program according to an embodiment of the present invention is a control program for a media transport device having a pick roller for feeding a medium, a first lift sensor positioned downstream of the upstream end of the nip width of the pick roller and on one side of the pick roller in the direction of medium transport, for detecting the lifting of the medium, a second lift sensor positioned downstream of the upstream end of the nip width of the pick roller and on the other side of the pick roller in the direction of transport, for detecting the lifting of the medium, a first detection sensor positioned on the same side of the pick roller as the first lift sensor for detecting the medium, and a second detection sensor positioned on the same side of the pick roller as the second lift sensor for detecting the medium, wherein the first or second lift sensor If the height of the media's levitation detected by this method is greater than or equal to the threshold, The medium is the specified medium. and The media transport device is instructed to perform abnormality control when it is determined that the medium is a predetermined medium, and in the determination process, if the first and second detection sensors detect that the side of the medium closest to the first detection sensor is ahead of the side closest to the second detection sensor, the first lift-up sensor Increase the threshold for this. It is characterized by the following: [Effects of the Invention]

[0010] The media transport device, control method, and control program according to the present invention enable more accurate determination of whether or not a medium should be subjected to abnormal control. [Brief explanation of the drawing]

[0011] [Figure 1] This is a perspective view of the media transport device 100. [Figure 2] This diagram shows the transport path inside the media transport device 100. [Figure 3] It is a perspective view of the lifting sensor 112. [Figure 4] It is a diagram schematically showing the arrangement of the lifting sensor 112, the second medium sensor 115, and the inclination sensor 116. [Figure 5] It is a functional block diagram of the medium conveyance device 100. [Figure 6] It is a functional block diagram of the storage device 140 and the processing circuit 150. [Figure 7] It is a flowchart showing the flow of the medium conveyance process. [Figure 8] It is a flowchart showing the flow of the determination process. [Figure 9] (A) is a schematic side view of the bound medium, and (B) is a schematic plan view of the bound medium. [Figure 10] (A) is a schematic plan view of the medium being conveyed while tilted, and (B) is a schematic view of the medium being conveyed while tilted as seen in the conveyance direction A2. [Figure 11] It is a diagram showing the conveyance path inside the medium conveyance device 200. [Figure 12] It is a diagram schematically showing the arrangement of the lifting sensor 112, the second medium sensor 115, and the inclination sensor 216. [Figure 13] It is a flowchart showing the flow of the medium conveyance process. [Figure 14] It is a functional block diagram of the processing circuit 350. [Embodiments for Carrying Out the Invention]

[0012] Hereinafter, embodiments of the present invention will be described while referring to the drawings. Note that the technical scope of the present invention is not limited to those embodiments, and extends to the invention described in the claims and its equivalents. <000097> Figure 1 is a perspective view showing a media transport device 100 according to an embodiment. The media transport device 100 is an image scanner. The media transport device 100 transports and images a medium which is a document. The medium is paper, cardboard, or card, etc. The media transport device 100 may also be a facsimile, copier, printer-multifunction device (MFP, Multifunction Peripheral), etc. The media transport device 100 may also be a printer that transports a medium which is the object to be printed.

[0014] In Figure 1, arrow A1 indicates the approximately vertical direction (height direction), arrow A2 indicates the conveying direction of the medium, arrow A3 indicates the discharge direction of the medium, and arrow A4 indicates the width direction perpendicular to the conveying direction A2 or discharge direction A3. Hereafter, "upstream" refers to the upstream direction of the conveying direction A2 or discharge direction A3, and "downstream" refers to the downstream direction of the conveying direction A2 or discharge direction A3.

[0015] The media transport device 100 includes a first housing 101, a second housing 102, a mounting table 103, a discharge table 104, an operating device 105, and a display device 106, etc.

[0016] The first housing 101 and the second housing 102 are examples of housings. The second housing 102 is located inside the first housing 101 and is rotatably engaged with the first housing 101 by a hinge so that it can be opened and closed when a jam occurs or when cleaning the inside of the media transport device 100.

[0017] The mounting platform 103 engages with the first housing 101 so that the medium to be transported can be placed on it. The mounting platform 103 is provided on the side of the first housing 101. The mounting platform 103 is movable in the height direction A1, and when no medium is being transported, it is located at the lower end of the first housing so that the medium can be easily placed on it, and when transporting medium, it rises to a position where the uppermost medium placed on it comes into contact with the pick roller described later.

[0018] A pair of side guides 103a are positioned at both ends of the upper surface of the mounting table 103 in the width direction A4, restricting the width direction of the media. The side guides 103a protrude upward from the upper surface of the mounting table 103 and extend in the transport direction A2. The media is placed between the pair of side guides 103a.

[0019] The discharge platform 104 is formed on the upper surface of the second housing 102. The discharge platform 104 has a mounting surface for placing media, and places media discharged from the discharge ports of the first housing 101 and the second housing 102 on it.

[0020] The operating device 105 has input devices such as buttons and an interface circuit for acquiring signals from the input devices. The operating device 105 accepts input operations from the user and outputs an operation signal corresponding to the user's input operation. The display device 106 has a display including liquid crystal, organic EL (Electro-Luminescence), etc. and an interface circuit for outputting image data to the display. The display device 106 displays the image data on the display. The display device 106 may be a liquid crystal display with a touch panel function. In this case, the operating device 105 has an interface circuit for acquiring input signals from the touch panel.

[0021] Figure 2 shows the transport path inside the media transport device 100.

[0022] The media transport device 100 has a first media sensor 110, a pick roller 111, a lifting sensor 112, a feeding roller 113, a separation roller 114, a second media sensor 115, a tilt sensor 116, first to fifth transport rollers 117a to e, first to fifth driven rollers 118a to e, and an imaging device 119, etc., in its internal transport path.

[0023] Note that the number of each of the pick roller 111, feed roller 113, separation roller 114, first to fifth conveying rollers 117a to e and / or first to fifth driven rollers 118a to e is not limited to one, but may be multiple. In that case, the multiple pick rollers 111, feed roller 113, separation roller 114, first to fifth conveying rollers 117a to e and / or first to fifth driven rollers 118a to e are arranged side by side with a gap of A4 in the width direction.

[0024] The surface of the first housing 101 facing the second housing 102 forms the first guide 101a of the transport path for the medium, and the surface of the second housing 102 facing the first housing 101 forms the second guide 102a of the transport path.

[0025] The first medium sensor 110 is positioned on the mounting base 103, which is upstream of the feeding roller 113 and the separation roller 114, and detects whether or not a medium is placed on the mounting base 103. The first medium sensor 110 detects whether or not a medium is placed on the mounting base 103 by using a contact detection sensor that supplies a predetermined current when the medium is in contact or when the medium is not in contact. The first medium sensor 110 generates and outputs a first medium signal having different signal values ​​depending on whether or not a medium is placed on the mounting base 103. Note that the first medium sensor 110 may be any other sensor capable of detecting whether or not a medium is placed on the mounting base 103, such as a light detection sensor.

[0026] The pick roller 111 is positioned in the second housing 102. The pick roller 111 comes into contact with the medium placed on the mounting platform 103, which is raised to approximately the same height as the medium transport path, and feeds the medium downstream.

[0027] The lift sensor 112 is located inside the second housing 102 and downstream of the pick roller 111. The lift sensor 112 detects the lifting of the medium fed by the pick roller 111. Lifting of the medium means that the fed medium is bent toward the second housing 102 relative to the transport path. The lift sensor 112 detects the lifting of the medium by generating and outputting a lift signal, which has a different signal value depending on whether the medium is lifting or not. The configuration of the lift sensor 112 will be described later with reference to Figure 3.

[0028] The feeding roller 113 is located inside the second housing 102 and downstream of the pick roller 111. The feeding roller 113 further feeds the medium fed by the pick roller 111 downstream. The separating roller 114 is located inside the first housing 101 and is positioned opposite the feeding roller 113. The separating roller 114 is a so-called brake roller or retard roller, and is rotatable in the opposite direction to the direction in which the medium is fed, or it can be stopped. The feeding roller 113 and the separating roller 114 separate the medium and feed it one sheet at a time. The feeding roller 113 is located above the separating roller 114, and the medium transport device 100 feeds the medium using a so-called top-feed method. Alternatively, the feeding roller 113 may be located below the separating roller 114, and the medium transport device 100 may feed the medium using a so-called bottom-feed method.

[0029] The second medium sensor 115 is positioned downstream of the feed roller 113 and the separation roller 114. The second medium sensor 115 detects the medium. The second medium sensor 115 is a recurrent prism sensor and comprises a light-emitting element such as an LED (Light Emitting Diode) and a light-receiving element such as a photodiode, which are positioned inside the first housing 101, and a light-guiding member such as a prism, which is positioned inside the second housing 102. The light-guiding member is positioned opposite the light-emitting element and the light-receiving element across the medium transport path, and is arranged to guide the light emitted from the light-emitting element to the light-receiving element. The second medium sensor 115 generates and outputs a signal as a second medium signal, which has a signal value corresponding to the intensity of the light detected by the light-receiving element, that is, a signal with different signal values ​​depending on whether or not the light emitted from the light-emitting element is blocked by the medium. For example, the second medium sensor 115 detects the medium when the second medium signal indicates that the light emitted from the light-emitting element is blocked by the medium. Note that the second medium sensor 115 may be any other sensor capable of detecting the medium, such as a contact detection sensor.

[0030] The tilt sensor 116 is positioned downstream of the feeding roller 113 and the separation roller 114. The tilt sensor 116 detects the tilt of the medium. The tilt sensor 116 has a first detection sensor 116-1 and a second detection sensor 116-2 that are spaced apart in the width direction A4 and detect the medium at their respective positions.

[0031] The first detection sensor 116-1 is a recurrent prism sensor similar to the second medium sensor 115, and comprises a light-emitting element such as an LED and a light-receiving element such as a photodiode, which are arranged inside the first housing 101, and a light-guiding member such as a prism, which is arranged inside the second housing 102. The first detection sensor 116-1 generates and outputs a signal as a first detection signal, which has a signal value corresponding to the intensity of light detected by the light-receiving element, that is, a signal with different signal values ​​depending on whether or not the light emitted from the light-emitting element is blocked by the medium. For example, the first detection sensor 116-1 detects the tip of the medium when the first detection signal changes from a state indicating that the light emitted from the light-emitting element is not blocked by the medium to a state indicating that it is blocked by the medium.

[0032] The second detection sensor 116-2 is also a recurrent prism sensor similar to the second medium sensor 115, and comprises a light-emitting element such as an LED and a light-receiving element such as a photodiode, which are arranged inside the first housing 101, and a light-guiding member such as a prism, which are arranged inside the second housing 102. The second detection sensor 116-2 generates and outputs a signal as a second detection signal that has a signal value corresponding to the intensity of light detected by the light-receiving element, that is, a signal that has a different signal value depending on whether or not the light emitted from the light-emitting element is blocked by the medium. For example, the second detection sensor 116-2 detects the tip of the medium when the second detection signal changes from a state indicating that the light emitted from the light-emitting element is not blocked by the medium to a state indicating that it is blocked by the medium.

[0033] The tilt sensor 116 detects that the medium is tilted when the time difference between the time when the first detection sensor 116-1 detects the leading edge of the medium and the time when the second detection sensor 116-2 detects the leading edge of the medium is greater than or equal to a threshold.

[0034] The first to fifth conveying rollers 117a to e and the first to fifth driven rollers 118a to e are provided downstream of the feeding roller 113 and the separation roller 114, facing each other. The first to fourth conveying rollers 117a to d and the first to fourth driven rollers 118a to d convey the medium fed by the feeding roller 113 and the separation roller 114 downstream. The fifth conveying roller 117e and the fifth driven roller 118e discharge the medium conveyed by the first to fourth conveying rollers 117a to d and the first to fourth driven rollers 118a to d to the discharge table 104.

[0035] The imaging device 119 is positioned downstream of the first transport roller 117a in the transport direction A2 and images the medium transported by the first transport roller 117a and the first driven roller 118a. The imaging device 119 includes a first imaging device 119a and a second imaging device 119b, which are positioned opposite each other across the transport path of the medium.

[0036] The first imaging device 119a has a line sensor using a 1:1 optical system type CIS (Contact Image Sensor) with CMOS (Complementary Metal Oxide Semiconductor) image sensors arranged linearly in the main scanning direction. The first imaging device 119a also has a lens that forms an image on the image sensor and an A / D converter that amplifies the electrical signal output from the image sensor and performs analog-to-digital (A / D) conversion. The first imaging device 119a captures the surface of the transported medium, generates an input image, and outputs it.

[0037] Similarly, the second imaging device 119b has a line sensor with a CIS of the 1:1 optical system type, which has CMOS image sensors arranged linearly in the main scanning direction. The second imaging device 119b also has a lens that forms an image on the image sensor and an A / D converter that amplifies the electrical signal output from the image sensor and performs analog-to-digital (A / D) conversion. The second imaging device 119b captures the back surface of the transported medium to generate and output an input image.

[0038] Furthermore, the imaging device 119 may consist of only one of the first imaging device 119a and the second imaging device 119b, and may read only one side of the medium. In addition, the first imaging device 119a and the second imaging device 119b may have a line sensor with a CIS of the same optical system type that uses a CCD (Charge Coupled Device) image sensor instead of a line sensor with a CMOS image sensor. In addition, the first imaging device 119a and the second imaging device 119b may have a line sensor with a reduction optical system type that uses a CMOS or CCD image sensor.

[0039] The medium placed between the pair of side guides 103a on the mounting table 103 is transported along the transport direction A2 between the first guide 101a and the second guide 102a by the pick roller 111 and the feed roller 113, which rotate in the direction of medium transport. The user can set either a separation mode, in which the medium is transported while being separated, or a non-separation mode, in which the medium is transported without being separated, as the feed mode of the medium transport device 100. The feed mode is set by the user operating the operating device 105 or an information processing device that communicates with the medium transport device 100. When the feed mode is set to separation mode, the separation roller 114 rotates or stops in the opposite direction to the medium transport direction. This restricts the transport of medium other than the separated medium and prevents double feeding. On the other hand, when the feed mode is set to non-separation mode, the separation roller 114 rotates in the direction of medium transport.

[0040] The medium is transported between the first guide 101a and the second guide 102a by the first transport roller 117a rotating in the direction of medium feeding, and is sent to the imaging position of the imaging device 119, where it is imaged by the imaging device 119. Furthermore, the medium is discharged onto the discharge table 104 by the second to fifth transport rollers 117b to e each rotating in the direction of medium feeding.

[0041] Figure 3 is a perspective view of the buoyancy sensor 112. The buoyancy sensor 112 has an arm 112a and a horseshoe-shaped sensor 112b.

[0042] Arm 112a is provided above the transport path of the medium, extending in the transport direction A2, and is positioned so that its lower surface is separated from the first guide 101a by a predetermined distance. Multiple lift sensors 112 may be arranged at intervals in the width direction A4. In this case, each arm 112a is positioned so that its height is the same as that of the first guide 101a. The downstream end 112c of arm 112a is rotatably engaged with the second housing 102 so that the upstream end 112d swings. As a result, when the medium lifts, the medium and arm 112a come into contact, causing the medium to rotate and lift the arm 112a. The distance between the lower surface of arm 112a and the first guide 101a when the medium is not lifted is appropriately set according to the magnitude of the deflection of the medium that needs to be detected by the lift sensors 112.

[0043] The horseshoe-shaped sensor 112b has a light-emitting element 112e, a light-receiving element 112f, and a connection part 112g that connects the light-emitting element 112e and the light-receiving element 112f. The light-emitting element 112e and the light-receiving element 112f are arranged to face each other. The light-emitting element 112e is an LED or the like, and emits light toward the light-receiving element 112f. The light-receiving element 112f is a photodiode or the like. The light-emitting element 112e and the light-receiving element 112f are examples of a light-emitting part and a light-receiving part, respectively. The light-receiving element 112f is provided facing the light-emitting element 112e with the arm 112a in between, and detects light from the light-emitting element 112e. The light-receiving element 112f generates and outputs a lift-up detection signal, which is an electrical signal corresponding to the intensity of the detected light. Note that the horseshoe-shaped sensor 112b is an example of a detector.

[0044] Arm 112a is positioned between the light-emitting element 112e and the light-receiving element 112f in its initial state, and is positioned so as not to face the light-emitting element 112e and the light-receiving element 112f when it is raised. In other words, arm 112a is formed to block light from the light-emitting element 112e to the light-receiving element 112f when it is not raised, and to allow light from the light-emitting element 112e to pass to the light-receiving element 112f when it is raised. The horseshoe-shaped sensor 112b generates a signal having a signal value corresponding to the intensity of light detected by the light-receiving element 112f, that is, a signal having different signal values ​​when the supplied medium is floating and when it is not floating, as the floating signal. For example, the floating sensor 112 detects the floating of the medium when the intensity of light detected by the light-receiving element 112f, as indicated by the floating signal, is above a threshold.

[0045] Figure 4 is a schematic diagram showing the arrangement of the buoyancy sensor 112, the second medium sensor 115, and the tilt sensor 116. Figure 4 is a top view of the transport path.

[0046] The lift sensor 112 includes a first lift sensor 112-1 and a second lift sensor 112-2. The first lift sensor 112-1 is positioned to the left of the pick roller 111 and the feed roller 113 in the direction of transport A2, i.e., in the width direction A4. The second lift sensor 112-2 is positioned to the right of the pick roller 111 and the feed roller 113 in the direction of transport A2, i.e., in the width direction A4. The configurations of the first lift sensor 112-1 and the second lift sensor 112-2 are the same except that they are symmetrical with respect to the width direction A4.

[0047] The first lift-up sensor 112-1 and the second lift-up sensor 112-2 are positioned at a predetermined distance from the pick roller 111 and the feed roller 113 in the width direction A4. The predetermined distance is set so that when a medium with the smallest length in the width direction A4 (e.g., A5 size) among the media that are generally likely to be bound with staples or clips is transported through the center of the width direction A4, the end of the medium in the width direction A4 passes under the arm 112a. This allows the lift-up sensor 112 to reliably detect the lift-up of a bound medium when a bound medium that has been bound with staples or clips is transported.

[0048] The upstream end 112d of the arm 112a of the first lift-up sensor 112-1 and the second lift-up sensor 112-2 is located upstream of the upstream end of the nip width 111a of the pick roller 111. Also, the downstream end 112c of the arm 112a of the first lift-up sensor 112-1 and the second lift-up sensor 112-2 is located downstream of the downstream end of the nip width 113a of the feed roller 113 and the separation roller 114. As a result, the lift-up sensor 112 detects the lift of the medium between the upstream end of the nip width 111a of the pick roller 111 and the downstream end of the nip width 113a of the feed roller 113 and the separation roller 114.

[0049] The second medium sensor 115 is positioned downstream of the feed roller 113 and the separation roller 114. The second medium sensor 115 is positioned between the two feed rollers 113, for example, in the center in the width direction A4. Multiple second medium sensors 115 may be arranged side by side with spacing between them along the width direction A4.

[0050] The first detection sensor 116-1 and the second detection sensor 116-2 of the tilt sensor 116 are arranged side by side with a gap in the width direction A4 downstream of the second medium sensor 115. The first detection sensor 116-1 is positioned to the left of the pick roller 111 and the feed roller 113 in the transport direction A2, i.e., in the width direction A4. The second detection sensor 116-2 is positioned to the right of the pick roller 111 and the feed roller 113 in the transport direction A2, i.e., in the width direction A4. In other words, the first detection sensor 116-1 is positioned on the same side of the pick roller 111 as the first lift-up sensor 112-1, and the second detection sensor 116-2 is positioned on the same side of the pick roller 111 as the second lift-up sensor 112-2.

[0051] Figure 5 is a block diagram showing an example of the schematic configuration of the media transport device 100. In addition to the configuration described above, the media transport device 100 further includes a motor 131, an interface device 132, a storage device 140, and a processing circuit 150, etc.

[0052] The motor 131 includes one or more motors. The motor 131 rotates the pick roller 111, the feeding roller 113, the separation roller 114, and the first to fifth transport rollers 117a to e by control pulses from the processing circuit 150 to feed and transport the medium. The first to fifth driven rollers 118a to e may be rotated by the motor 131 rather than being driven by the rotation of each transport roller.

[0053] The interface device 132 has an interface circuit similar to a serial bus such as USB. The interface device 132 is electrically connected to an information processing device (not shown) (e.g., a personal computer, a portable information terminal, etc.) to transmit and receive input images and various types of information. The media transport device 100 may instead include a communication unit having an antenna for transmitting and receiving wireless signals and a communication interface circuit for transmitting and receiving signals via a wireless communication line, instead of the interface device 132. The communication protocol used by the communication interface circuit is, for example, a wireless LAN (Local Area Network).

[0054] The storage device 140 includes memory devices such as RAM (Random Access Memory) and ROM (Read Only Memory), fixed disk devices such as hard disks, or portable storage devices such as flexible disks and optical disks. The storage device 140 also stores computer programs, databases, tables, etc., used for various processes of the media transport device 100. The computer programs may be installed into the storage device 140 from a computer-readable, non-temporary portable recording medium using a known setup program. Examples of portable recording media include CD-ROMs (Compact Disc Read Only Memory) and DVD-ROMs (Digital Versatile Disc Read Only Memory).

[0055] The processing circuit 150 operates based on a program pre-stored in the memory device 140. The processing circuit 150 is, for example, a CPU (Central Processing Unit). The processing circuit 150 may also be a DSP (Digital Signal Processor), LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), etc.

[0056] The processing circuit 150 is connected to the operating device 105, display device 106, first medium sensor 110, lift sensor 112, second medium sensor 115, tilt sensor 116, imaging device 119, motor 131, interface device 132, and storage device 140, and controls each of these parts. The processing circuit 150 controls the motor 131 to transport the medium, controls the imaging device 119 to acquire the input image, and transmits the acquired input image to the information processing device via the interface device 132. The processing circuit 150 also receives the lift detection signal from the lift sensor 112, the second medium signal from the second medium sensor 115, and the tilt sensor 11 Based on the signal received from 6, it is determined whether the transported medium is a bound medium or not.

[0057] Figure 6 shows a schematic configuration of the storage device 140 and the processing circuit 150.

[0058] The memory device 140 stores various programs, such as the control program 141 and the determination program 142. Each of these programs is a functional module implemented by software running on the processor. The processing circuit 150 reads each program stored in the memory device 140 and functions as the control unit 151 and determination unit 152 by operating according to each program it has read.

[0059] Figure 7 is a flowchart showing the operation flow of the media transport process performed by the media transport device 100. The media transport process is realized by the processing circuit 150 cooperating with each element of the media transport device 100 based on a program stored in the storage device 140.

[0060] First, the control unit 151 waits until it receives an operation signal instructing the reading of the medium (S101). The operation signal is supplied from the operating device 105 to the control unit 151 in response to the user inputting a medium reading instruction to the operating device 105. Alternatively, the operation signal may be supplied from the information processing device via the interface device 132 in response to the user inputting a reading instruction to the information processing device.

[0061] Next, the control unit 151 determines whether or not a medium is placed on the mounting table 103 based on the first medium signal output from the first medium sensor 110 (S102). If no medium is placed (S102-No), the medium imaging process ends.

[0062] If a medium is placed on the platform (S102-Yes), the control unit 151 drives the motor to move the platform 103 and raise the platform 103 to a position where the medium can be fed. The control unit 151 drives the motor 131 to rotate the pick roller 111, the feeding roller 113, the separation roller 114 and the first to fifth transport rollers 117a to e, and feeds and transports the medium placed on the platform 103 (S103).

[0063] Next, the control unit 151 determines whether or not the medium has been detected by the second medium sensor 115 based on the second medium signal output from the second medium sensor 115 (S104). The control unit 151 determines that the leading edge of the medium has reached the position of the second medium sensor 115 and that the medium has been detected by the second medium sensor 115 when the second medium signal changes from a state indicating that the light emitted from the light-emitting element is not blocked by the medium to a state indicating that it is blocked by the medium. If the medium has not been detected by the second medium sensor 115 (S104-No), the process returns to S104, and the control unit 151 waits until the medium is detected by the second medium sensor 115.

[0064] If the medium is detected by the second medium sensor 115 (S104-Yes), the determination unit 152 performs a determination process to determine whether or not the medium is a bound medium (S105). Details of the determination process will be described later.

[0065] Next, the control unit 151 obtains the result of the determination process from the determination unit 152 and determines whether the medium is a bound medium or not (S106). If the medium is a bound medium (S106-Yes), the control unit 151 stops the transport of the medium by stopping the motor 131 (S107). The control unit 151 also displays a screen on the display device 106 indicating that there was an abnormality in the transport of the medium. This completes the transport of the medium. Note that stopping the transport of the medium and displaying a screen on the display device 106 indicating that there was an abnormality in the transport of the medium are examples of abnormality control.

[0066] If the medium is not a bound medium (S106-No), the control unit 151 images the medium (S108). The control unit 151 waits until the leading edge of the medium reaches the imaging start position between the second medium sensor 115 and the imaging device 119. For example, the control unit 151 determines that the leading edge of the medium has reached the imaging start position when it has been transported a predetermined distance after reaching the position of the second medium sensor 115. When the leading edge of the medium reaches the imaging start position, the control unit 151 controls the imaging device 119 to sequentially image the medium as it is transported and generate an input image. The control unit 151 transmits the generated input image to the information processing device via the interface device 132.

[0067] Next, the control unit 151 determines whether or not a medium is placed on the mounting table 103 based on the first medium signal output from the first medium sensor 110 (S109). If a medium is placed (S109-Yes), the medium transport process returns to S104, and the control unit 151 waits until the next medium is detected by the second medium sensor 115. If no medium is placed (S109-No), the control unit 151 stops the motor 131. This completes the medium transport process.

[0068] Figure 8 is a flowchart showing the flow of the determination process performed by the media transport device 100 in S105 of the media transport process. In the determination process, it is determined whether or not the media is a bound medium.

[0069] First, the determination unit 152 starts timing the determination period (S201). The determination period is the period from when the medium reaches the second medium sensor 115 until the medium has been transported a predetermined distance. In this case, the determination unit 152 starts counting the control pulses supplied to the motors 131 that drive the first to fifth transport rollers 117a to e. The determination period may also be the period from when the medium reaches the second medium sensor 115 until a predetermined time has elapsed. In this case, the determination unit 152 starts measuring the elapsed time from the time the medium reached the second medium sensor 115. For example, the determination period is set to the period until the trailing end of a medium of standard size (e.g., A4 size) passes the feed roller 113 and the separation roller 114.

[0070] Next, the determination unit 152 determines whether or not the floating of the medium has been detected by the floating sensor 112, based on the floating signal output by the floating sensor 112 (S202). The determination unit 152 determines that the floating of the medium has been detected if the intensity of the light detected by the light receiving element 112f, indicated by the floating signal, is above a threshold.

[0071] If the lifting sensor 112 detects that the medium is lifting (S202-Yes), the determination unit 152 determines that the medium is a bound medium (S203). This completes the determination process.

[0072] If the floating sensor 112 does not detect the floating of the medium (S202-No), the determination unit 152 determines whether or not the tilt detection sensor 116 has detected that the medium is tilted (S204). The determination unit 152 determines that the medium is tilted if the side of the medium with the first detection sensor 116-1 is ahead of the side with the second detection sensor 116-2, or if the side of the medium with the second detection sensor 116-2 is ahead of the side with the first detection sensor 116-1.

[0073] For example, the determination unit 152 determines that the side of the medium closest to the first detection sensor 116-1 is ahead of the side of the second detection sensor 116-2 if the leading edge of the medium is detected by the first detection sensor 116-1, and the leading edge of the medium is not detected by the second detection sensor 116-2 even after a predetermined time has elapsed since the first detection sensor 116-1 detected the leading edge of the medium. Also, the determination unit 152 determines that the side of the medium closest to the second detection sensor 116-2 is ahead of the side of the first detection sensor 116-1 if the leading edge of the medium is detected by the second detection sensor 116-2, and the leading edge of the medium is not detected by the second detection sensor 116-2 even after a predetermined time has elapsed since the second detection sensor 116-2 detected the leading edge of the medium.

[0074] If the leading edge of the medium is not detected by either the first detection sensor 116-1 or the second detection sensor 116-2, the determination unit 152 determines that the medium is not tilted. If the leading edge of the medium is detected by only one of the first detection sensor 116-1 or the second detection sensor 116-2, but a predetermined amount of time has not elapsed since the medium was detected, the determination unit 152 also determines that the medium is not tilted. If the medium is detected by the other of the first detection sensor 116-1 or the second detection sensor 116-2 before a predetermined amount of time has elapsed since the first detection sensor detected it, the determination unit 152 also determines that the medium is not tilted.

[0075] The predetermined time is set based on the allowable tilt of the medium. As will be described later, the detection of the medium's tilt is for detecting whether the rear end of the medium is riding on the side guide 103a. Therefore, the allowable tilt is set to a range in which, for example, the rear end of the medium does not come into contact with the side guide 103a when the front end of the medium is positioned in the center of the width direction A4. The predetermined time is set to the time difference between the time when the first detection sensor 116-1 detects the front end of the medium and the time when the second detection sensor 116-2 detects the front end of the medium when a medium with the maximum allowable tilt is transported.

[0076] If tilting of the medium is detected (S204-Yes), the determination unit 152 makes it difficult to determine that the medium is a bound medium based on the detection result of the lifting of the medium by the lifting sensor 112 on the side of the medium that is ahead of the first lifting sensor 112-1 and the second lifting sensor 112-2 (S205). In other words, if the determination unit 152 detects that the side of the medium with the first detection sensor 116-1 is ahead of the side with the second detection sensor 116-2, it makes it difficult to determine that the medium is a bound medium based on the detection result of the first lifting sensor 112-1. Also, if the determination unit 152 detects that the side of the medium with the second detection sensor 116-2 is ahead of the side with the first detection sensor 116-1, it makes it difficult to determine that the medium is a bound medium based on the detection result of the second lifting sensor 112-2.

[0077] Making it difficult to determine that a medium is a bound medium based on the detection result of the lifting of the medium by the lifting sensor 112 on the leading side of the medium means, for example, not using the detection result of the lifting sensor 112 on the leading side to determine if it is a bound medium. For example, if the side of the medium with the first detection sensor 116-1 is leading, the determination unit 152 determines in S202 that the medium is a bound medium if the second lifting sensor 112-2 detects that the medium is lifting, but the determination unit 152 does not determine that the medium is a bound medium if only the first lifting sensor 112-1 detects that the medium is lifting. Similarly, if the side of the medium with the second detection sensor 116-2 is leading, the determination unit 152 determines in S202 that the medium is a bound medium if the first lifting sensor 112-1 detects that the medium is lifting, but the determination unit 152 does not determine that the medium is a bound medium if only the second lifting sensor 112-2 detects that the medium is lifting.

[0078] If no tilt of the media is detected (S204-No), the determination process proceeds to S206.

[0079] Next, the determination unit 152 determines whether the determination period has ended (S206). For example, the determination unit 152 determines whether the determination period has ended based on the number of control pulses supplied to the motor 131 since the second medium sensor 115 detected the medium.

[0080] If the judgment period has not ended (S206-No), the judgment process proceeds to S202.

[0081] If the judgment period ends (S206-Yes), the judgment process will terminate.

[0082] The following explains the principles of the decision-making process.

[0083] Figure 9(A) is a schematic side view of a binding medium that has reached the positions of the feed roller 113 and the separation roller 114. In the example shown in Figure 9(A), the binding medium consists of a lower medium M1 and an upper medium M2 bound together by a binding section S. When the binding medium reaches the positions of the feed roller 113 and the separation roller 114, the lower medium M1 stops due to the rotation of the separation roller 114, and only the upper medium M2 attempts to move in the transport direction A2 due to the rotation of the feed roller 113. At this time, since the leading edge of the upper medium M2 is fixed to the lower medium M1 by the binding section S, a lift occurs between the area T in contact with the feed roller 113 and the binding section S of the upper medium M2. Therefore, it is possible to determine whether the medium is a binding medium or not based on whether or not the lift of the medium is detected by the lift sensor 112.

[0084] Figure 9(B) is a schematic diagram of the binding medium in plan view after it has reached the positions of the feed roller 113 and the separation roller 114. As shown in Figure 9(B), the upper medium M2 attempts to move in the transport direction A2 due to the rotation of the feed roller 113, but because one side of its leading edge is bound by the binding section S, it tilts so that the side opposite to the binding section S leads in the transport direction A2. In other words, when the binding medium is being transported, one side of the leading edge of the medium leads in the transport direction A2, while the other side lifts up.

[0085] Figure 10(A) is a schematic plan view of a normal medium (a non-bound medium) being transported at an angle with respect to the transport direction A2, and Figure 10(B) is a schematic view of a normal medium being transported at an angle, viewed toward the transport direction A2. When the tilt of the medium is large, the rear end of the medium may ride up onto the side guide 103a of the mounting table 103 when the medium is fed. In this case, a lift occurs between the portion V of the medium that rides onto the side guide 103a and the area T in contact with the pick roller 111. Therefore, even when a normal medium is being transported at an angle, the lift sensor 112 can detect the lift of the medium.

[0086] When the rear end of the medium rides up onto the side guide 103a, the medium is tilted, and the side that rides up onto the side guide 103a is ahead of the other side in the width direction A4. In the examples shown in Figures 10(A) and (B), the right side of the medium in the transport direction A2 is ahead of the left side, so the right side of the rear end rides up onto the side guide 103a. Therefore, the lift of the medium also occurs to the right of the pick roller 111. In other words, when the medium is normally transported at an angle, one side of the leading edge of the medium is ahead in the transport direction A2, and lift occurs on that side.

[0087] Therefore, the determination unit 152 is less likely to determine that a medium is a bound medium based on the detection result of the lifting of the medium by the lifting sensor 112 on the leading side of the medium, thereby preventing the misidentification of a medium that has been transported at an angle as a bound medium.

[0088] As explained above, when one side of the medium is ahead of the other side in the transport direction A2, the medium transport device 100 makes it difficult to determine that the medium is a bound medium based on the detection result of the lifting of the medium by the lifting sensor 112 on one side. This enables the medium transport device 100 to distinguish between bound medium and normal medium that has been transported at an angle, and to determine with higher accuracy whether or not a medium should be subjected to abnormal control.

[0089] In the above explanation, in S205 of the determination process, the determination unit 152 does not use the detection result of the lift sensor 112 on the leading side of the medium to determine the binding medium, but the example is not limited to this. The determination unit 152 may shorten the determination period for the lift sensor 112 on the leading side.

[0090] In this case, in S201 of the determination process, the determination unit 152 starts timing the determination period for each of the first lifting sensor 112-1 and the second lifting sensor 112-2. In S205, the determination unit 152 shortens the determination period for the preceding lifting sensor 112 by a predetermined time. Also, in S206, the determination unit 152 determines whether the determination period for each of the first lifting sensor 112-1 and the second lifting sensor 112-2 has ended. If the determination period for only one of the first lifting sensor 112-1 and the second lifting sensor 112-2 has ended, the determination unit 152 does not use the detection result of the lifting sensor 112 whose determination period has ended for determining the binding medium, and the determination process returns to S202. If the determination periods for both the first lifting sensor 112-1 and the second lifting sensor 112-2 have ended, the determination process ends. By appropriately setting the judgment period after the change, the media transport device 100 can distinguish between bound media and media that have been transported at an angle with high accuracy, and determine with higher accuracy whether or not a medium should be subjected to abnormal control.

[0091] In the above description, the levitation sensor 112 is assumed to have an arm 112a and a horseshoe-shaped sensor 112b, but it is not limited to this example. The levitation sensor 112 may also be an optical distance measuring sensor comprising a light-emitting element such as an LED positioned above the transport path of the medium, and a light-receiving element such as a photodiode that detects light emitted from the LED and reflected by the medium. In this case, the levitation sensor 112 outputs a signal as a levitation signal that shows different values ​​depending on the time from when the light-emitting element emits light until the light-receiving element receives the light. For example, the levitation sensor 112 detects levitation of the medium when the time from when the light-emitting element emits light until the photodiode receives the light, as indicated by the levitation signal, is below a threshold.

[0092] Furthermore, in this case, in the determination process S205, the determination unit 152 may make it more difficult to determine that the medium is a bound medium based on the detection result of the medium's lift by the lift sensor 112 on the leading side of the medium by reducing the threshold of the lift sensor 112 on the leading side of the medium. For example, if the side of the medium with the first detection sensor 116-1 is leading, the determination unit 152 reduces the threshold of the first lift sensor 112-1. Also, if the side of the medium with the second detection sensor 116-2 is leading, the determination unit 152 reduces the threshold of the second lift sensor 112-2. By appropriately setting the changed thresholds, the medium transport device 100 can distinguish between bound medium and tilted medium with high accuracy and determine with higher accuracy whether or not a medium should be subjected to abnormal control.

[0093] Figure 11 shows the transport path of the medium transport device 200 according to another embodiment. The medium transport device 200 differs from the medium transport device 100 in that it has a tilt sensor 216 instead of a tilt sensor 116.

[0094] The tilt sensor 216 is positioned upstream of the pick roller 111. The tilt sensor 216 detects the tilt of the medium. The tilt sensor 216 has a first speed sensor 216-1 and a second speed sensor 216-2 that are spaced apart in the width direction A4 and detect the speed of the medium.

[0095] The first speed sensor 216-1 is, for example, a slit-type encoder. The first speed sensor 216-1 includes a slit and a rotating member that rotates as the medium passes through, a light-emitting element such as an LED, and a light-receiving element such as a photodiode. When light emitted from the light-emitting element such as an LED passes through the rotating slit, light pulses are generated. The first speed sensor 216-1 generates and outputs a signal corresponding to the width or interval of the light pulses detected by the light-receiving element, that is, a signal corresponding to the moving speed of the medium, as a first speed signal.

[0096] The second speed sensor 216-2 has the same configuration as the first speed sensor 216-1. The second speed sensor 216-2 generates and outputs a signal corresponding to the width or interval of the light pulses detected by the photodetector, that is, a signal corresponding to the moving speed of the medium, as a second speed signal.

[0097] The tilt sensor 216 detects that the medium is tilted when the difference between the moving speed of the medium indicated by the first velocity signal and the moving speed of the medium indicated by the second velocity signal is greater than or equal to a threshold.

[0098] The first speed sensor 216-1 and the second speed sensor 216-2 may also be magnetic encoders that detect changes in magnetism caused by the rotation of a rotating member equipped with a magnet.

[0099] Figure 12 schematically shows the arrangement of the buoyancy sensor 112, the second medium sensor 115, and the tilt sensor 216. Figure 12 is a view of the transport path from above.

[0100] The upstream end 112d of the arm 112a of the first lift-up sensor 112-1 and the second lift-up sensor 112-2 is located upstream of the upstream end of the nip width 111a of the pick roller 111. Also, the downstream end 112c of the arm 112a of the first lift-up sensor 112-1 and the second lift-up sensor 112-2 is located downstream of the upstream end of the nip width of the first conveyor roller 117a. As a result, the lift-up sensor 112 detects the lift of the medium between the upstream end of the nip width 111a of the pick roller 111 and the upstream end of the nip width of the first conveyor roller 117a.

[0101] The first speed sensor 216-1 and the second speed sensor 216-2 of the tilt sensor 216 are arranged side by side with a gap in the width direction A4 on the upstream side of the pick roller 111. The first speed sensor 216-1 is positioned to the left of the pick roller 111 and the feed roller 113 in the transport direction A2, i.e., in the width direction A4. The second speed sensor 216-2 is positioned to the right of the pick roller 111 and the feed roller 113 in the transport direction A2, i.e., in the width direction A4. In other words, the first speed sensor 216-1 is positioned on the same side of the pick roller 111 as the first lift sensor 112-1, and the second speed sensor 216-2 is positioned on the same side of the pick roller 111 as the second lift sensor 112-2.

[0102] Figure 13 is a flowchart showing the operation flow of the media transport process performed by the media transport device 200. The media transport process is realized by the processing circuit 150 cooperating with each element of the media transport device 200 based on a program stored in the memory device 140. The processes S301-S303 and S307-S311 in Figure 13 are the same as the processes S101-S103 and S105-S109 in Figure 7, so their explanation is omitted, and only S304-S306 will be explained below.

[0103] In S303, after the motor 131 is driven, the determination unit 152 determines whether or not the tilt detection sensor 216 has detected that the medium is tilted (S304). The determination unit 152 determines that the tilt of the medium has been detected if the side of the medium with the first speed sensor 216-1 is ahead of the side with the second speed sensor 216-2, or if the side of the medium with the second speed sensor 216-2 is ahead of the side with the first speed sensor 216-1. For example, the determination unit 152 determines that the tilt of the medium has been detected by the tilt detection sensor 216 if the difference between the moving speed of the medium indicated by the first speed signal and the moving speed of the medium indicated by the second speed signal is greater than or equal to a threshold.

[0104] If it is detected that the medium is tilted (S304-Yes), the determination unit 152 makes it difficult to determine that the medium is a bound medium based on the detection result of the medium lifting by the lifting sensor 112, which is the leading side of the medium, of the first lifting sensor 116-1 and the second lifting sensor 116-2 (S305).

[0105] If no tilting of the media is detected (S304-No), the media transport process proceeds to S306.

[0106] Next, the control unit 151 determines whether or not the medium has been detected by the second medium sensor 115 based on the second medium signal output from the second medium sensor 115 (S306). If the medium has not been detected by the second medium sensor 115 (S306-No), the process returns to S304, and the control unit 151 waits until the tilt of the medium is detected by the tilt sensor 216 or until the medium is detected by the second medium sensor 115.

[0107] In the determination process performed by the media transport device 200, the processes from S204 to S205 are omitted.

[0108] In this manner, the media transport device 200 detects the tilt of the media using a tilt sensor 216 positioned upstream of the pick roller. This allows the media transport device 200 to stop transporting the media at the point when the lift sensor 112 detects the media lifting before the second media sensor 115 detects the media, thereby preventing damage to the bound media.

[0109] Figure 14 shows a schematic configuration of a processing circuit 350 in a media transport device according to another embodiment. The processing circuit 350 is used in place of the processing circuit 150 and performs media transport processing. The processing circuit 350 includes a control circuit 351 and a determination circuit 352, etc. Each of these parts may be composed of an independent integrated circuit, microprocessor, firmware, etc.

[0110] 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 operation signals from the operating device 105, first medium signals from the first medium sensor 110, and determination results from the determination circuit 352, and controls the motor 131 based on the received signals and determination results. The control circuit 351 also receives input images from the imaging device 119 and transmits them to the information processing device via the interface device 132.

[0111] The determination circuit 352 is an example of a determination unit and has the same functions as the determination unit 152. The determination circuit 352 receives a lift detection signal, a second medium signal, and the first and second detection signals, etc., from the lift sensor 112, the second medium sensor 115, and the tilt sensor 116, respectively. Based on each of the received signals, the determination circuit 352 determines whether the medium is a bound medium or not, and outputs the determination result to the control circuit 351.

[0112] As explained above, the media transport device enables proper detection of the bound media even when using the processing circuit 350.

[0113] Those skilled in the art will understand that various changes, substitutions, and modifications can be made without departing from the spirit and scope of the present invention. For example, the embodiments and modifications described above may be combined as appropriate within the scope of the invention. [Explanation of symbols]

[0114] 100 Media transport device 111 Pick Roller 112 Lifting Sensor 113 Feeding roller 114 Separation Roller 115 Second medium sensor 116 Tilt Sensor 151 Control Unit 152 Judgment section

Claims

1. A pick roller for feeding the media, A first lift sensor is positioned downstream of the upstream end of the nip width of the pick roller, on one side of the pick roller in the direction of conveying the medium, and detects the lifting of the medium. A second lift sensor is positioned downstream of the upstream end of the nip width of the pick roller, on the other side of the pick roller in the direction of transport, and detects the lifting of the medium. A first detection sensor is positioned on the same side as the first lifting sensor with respect to the pick roller and detects the medium, A second detection sensor is positioned on the same side as the second lifting sensor with respect to the pick roller and detects the medium, A determination unit that determines that the medium is a predetermined medium when the height of the floating of the medium detected by the first or second floating sensor is equal to or greater than a threshold, The system includes a control unit that performs abnormality control when it is determined that the medium is the predetermined medium, The determination unit increases the threshold value for the first lift-up sensor when the first and second detection sensors detect that the side of the medium closest to the first detection sensor is ahead of the side closest to the second detection sensor. A media transport device characterized by the following features.

2. The system further includes a separation roller positioned downstream of the pick roller in the conveying direction, The first and second detection sensors are media sensors that detect the medium at their respective positions, and are positioned downstream of the downstream end of the nip width of the separation roller, at intervals in a direction perpendicular to the conveying direction. The media transport device according to claim 1.

3. The further comprising a separation roller positioned downstream of the pick roller in the conveying direction, The first and second detection sensors are speed sensors that measure the speed of the medium, and are positioned upstream of the upstream end of the nip width of the separation roller, at intervals in a direction perpendicular to the conveying direction. The media transport device according to claim 1.

4. The further comprising a separation roller positioned downstream of the pick roller in the conveying direction, The determination unit, If the first or second floating sensor detects the floating of the medium during a predetermined determination period immediately after the medium has passed the separation roller, it is determined that the medium is the predetermined medium. When it is detected that the side of the medium where the first detection sensor is located is ahead of the side where the second detection sensor is located, the determination period for the first floating sensor is shortened. The media transport device according to claim 1.

5. The medium is fed by a pick roller. A first lift sensor, positioned downstream of the upstream end of the nip width of the pick roller and on one side of the pick roller in the direction of conveying the medium, detects the lifting of the medium. A second lift sensor, positioned downstream of the upstream end of the nip width of the pick roller and on the other side of the pick roller in the direction of transport, detects the lifting of the medium. The medium is detected by a first detection sensor positioned on the same side as the first lifting sensor relative to the pick roller. The medium is detected by a second detection sensor positioned on the same side as the second lifting sensor relative to the pick roller. If the height of the floating of the medium detected by the first or second floating sensor is greater than or equal to a threshold, it is determined that the medium is a predetermined medium. This includes performing abnormality control when it is determined that the medium is the predetermined medium, In making the determination, if the first and second detection sensors detect that the side of the medium closest to the first detection sensor is ahead of the side closest to the second detection sensor, the threshold value for the first lift-up sensor is increased. A media transport method characterized by the following:

6. A control program for a media transport device comprising: a pick roller for feeding media; a first lift sensor positioned downstream of the upstream end of the nip width of the pick roller and on one side of the pick roller in the direction of media transport, for detecting the lifting of the media; a second lift sensor positioned downstream of the upstream end of the nip width of the pick roller and on the other side of the pick roller in the direction of transport, for detecting the lifting of the media; a first detection sensor positioned on the same side of the pick roller as the first lift sensor for detecting the media; and a second detection sensor positioned on the same side of the pick roller as the second lift sensor for detecting the media. If the height of the floating of the medium detected by the first or second floating sensor is greater than or equal to a threshold, it is determined that the medium is a predetermined medium. If the medium is determined to be the predetermined medium, the medium transport device is instructed to perform abnormality control. In making the determination, if the first and second detection sensors detect that the side of the medium closest to the first detection sensor is ahead of the side closest to the second detection sensor, the threshold value for the first lift-up sensor is increased. A control program characterized by the following features.

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