MEDIUM CONVEYING APPARATUS TO DETECT PREDETERMINED MEDIUM BASED ON LIFT OF MEDIUM

A medium conveying apparatus includes a pick roller feeding a medium, a separation roller located on a downstream side of the pick roller, a conveyance roller located on a downstream side of the separation roller, a medium sensor being located on a downstream side of the separation roller and detecting the medium, a lift sensor detecting a lift of the medium on an upstream side of the conveyance roller, a passing sensor being located on an upstream side of the separation roller and detecting passing of the medium, and a processor to determine that the medium is a predetermined medium when a lift of the medium and passing of the medium are detected in a predetermined period after the medium is detected, and execute abnormality control when the medium is determined to be the predetermined medium.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of prior Japanese Patent Application No. 2022-115773, filed on Jul. 20, 2022, the entire contents of which are incorporated herein by reference.

FIELD

The present invention relates to a medium conveying apparatus to detect a predetermined medium based on a lift of a medium.

BACKGROUND

In general, a medium conveying apparatus conveying and imaging a medium, such as a scanner, sequentially separates and conveys a plurality of stacked media located on a loading tray. However, when a plurality of media are bound by a staple or the like, the media may be damaged when the media are separated. Therefore, it is required of the medium conveying apparatus to suitably detect such a bound medium and to execute abnormality control such as stopping conveyance.

PTL 1 (Japanese Unexamined Patent Publication (Kokai) No. 2020-83563) discloses an image reading apparatus including a height detection sensor detecting the height of an original surface and an original surface detection sensor being located on an upstream side of the height detection sensor and facing a direction different from the height detection sensor. When the height of an original surface detected by the height detection sensor exceeds a threshold value, or a lift of an original occurs and the original is detected by the original surface detection sensor, the image reading device in PTL 1 determines that a bound original is fed.

SUMMARY

It is an object to provide a medium conveying apparatus, a medium conveying method, and a computer-readable, non-transitory storage medium storing a computer program for more precisely detecting a medium on which abnormality control is to be executed.

According to an aspect of the apparatus, provided is a medium conveying apparatus including a pick roller to feed a medium, a separation roller located on a downstream side of the pick roller in a conveying direction of the medium, a conveyance roller located on a downstream side of the separation roller in the conveying direction, a medium sensor located on a downstream side of the separation roller in the conveying direction to detect the medium a lift sensor to detect a lift of the medium on an upstream side of the conveyance roller in the conveying direction, a passing sensor located on an upstream side of the separation roller in the conveying direction to detect passing of the medium, and a processor to determine that the medium is a predetermined medium when a lift of the medium is detected by the lift sensor and passing of the medium is detected by the passing sensor in a predetermined period after the medium is detected by the medium sensor, and execute abnormality control when the medium is determined to be the predetermined medium.

According to an aspect of the method, provided is a medium conveying method including feeding a medium by a pick roller, detecting the medium by a medium sensor located on a downstream side of a separation roller in the conveying direction, the separation roller being located on a downstream side of the pick roller in a conveying a direction of the medium, detecting a lift of the medium on an upstream side of a conveyance roller by a lift sensor, the conveyance roller being located on a downstream side of the separation roller in the conveying direction, detecting passing of the medium by a passing sensor located on an upstream side of the separation roller in the conveying direction, determining, by a processor, that the medium is a predetermined medium when a lift of the medium is detected by the lift sensor and passing of the medium is detected by the passing sensor in a predetermined period after the medium is detected by the medium sensor, and executing, by the processor, abnormality control when the medium is determined to be the predetermined medium.

According to an aspect of the computer-readable, non-transitory medium, provided is a computer-readable, non-transitory storage medium storing a computer program for a medium conveying apparatus including a pick roller feeding a medium; a separation roller located on a downstream side of the pick roller in a conveying direction of the medium; a conveyance roller located on a downstream side of the separation roller in the conveying direction; a medium sensor being located on a downstream side of the separation roller in the conveying direction and detecting the medium; a lift sensor detecting a lift of the medium on an upstream side of the conveyance roller in the conveying direction; and a passing sensor being located on an upstream side of the separation roller in the conveying direction and detecting passing of the medium, the computer program causing the medium conveying apparatus to execute a process, the process including determining that the medium is a predetermined medium when a lift of the medium is detected by the lift sensor and passing of the medium is detected by the passing sensor in a predetermined period after a medium is detected by the medium sensor, and executing abnormality control when the medium is determined to be the predetermined medium.

DESCRIPTION OF EMBODIMENTS

FIG.1is a perspective view illustrating a medium conveying apparatus100according to an embodiment. The medium conveying apparatus100is an image scanner. The medium conveying apparatus100conveys and images a medium being an original. A medium is a paper, a thick paper, a card, or the like. The medium conveying apparatus100may also be a facsimile, a copying machine, a multifunctional peripheral (MFP), or the like. The medium conveying apparatus100may also be a printer conveying a medium being an object being printed on.

InFIG.1, an arrow A1indicates an almost vertical direction (height direction), an arrow A2indicates a conveying direction of a medium, an arrow A3indicates an ejecting direction of a medium, and an arrow A4indicates a width direction orthogonal to the conveying direction A2or the ejecting direction A3. An upstream side hereinafter refers to an upstream side in the conveying direction A2or the ejecting direction A3, and a downstream side refers to a downstream side in the conveying direction A2or the ejecting direction A3.

The medium conveying apparatus100includes a first housing101, a second housing102, a loading tray103, an output tray104, an operation device105, and a display device106.

The first housing101and the second housing102are examples of a housing. The second housing102is located inside the first housing101and is rotatably engaged with the first housing101by a hinge in such a way as to be openable when a jam occurs or cleaning of the inside of the medium conveying apparatus100is performed.

The loading tray103is engaged with the first housing101in such a way as to be able to place a medium to be conveyed. The loading tray103is provided on the side of the first housing101. The loading tray103is movable in the height direction A1. The loading tray103is positioned at the lower end of the first housing in such a way that a medium can be easily located when a medium is not conveyed. The loading tray103is raised to a position where a medium located on the uppermost side comes in contact with a pick roller to be described later when a medium is conveyed.

The output tray104is formed on the top surface of the second housing102. The output tray104includes a placement surface for placing a medium ejected from an outlet of the first housing101and the second housing102.

The operation device105includes an input device such as a button, and an interface circuit acquiring a signal from the input device. The operation device105accepts an input operation by a user and outputs an operation signal based on the input operation by the user. The display device106includes a display including a liquid crystal display, an organic electro-luminescence (EL) display, or the like and an interface circuit outputting image data to the display. The display device106displays the image data on the display. The display device106may be a liquid crystal display with a touch panel function. In this case, the operation device105includes an interface circuit acquiring an input signal from the touch panel.

FIG.2is a diagram illustrating a conveyance path inside the medium conveying apparatus100.

The conveyance path inside the medium conveying apparatus100includes a first medium sensor110, a passing sensor111, a pick roller112, a lift sensor113, a feed roller114, a separation roller115, a second medium sensor116, first to fifth conveyance rollers117atoe, first to fifth driven rollers118atoe, and an imaging device119.

The number of the pick roller112, the feed roller114, the separation roller115, the first to fifth conveyance rollers117atoe, and/or the first to fifth driven rollers118atoeis not limited to one and may be more than one. In that case, the plurality of pick rollers112, the feed rollers114, the separation roller115, the first to fifth conveyance rollers117atoe, and/or the first to fifth driven rollers118atoeare respectively spaced in the width direction A4.

A surface of the first housing101facing the second housing102forms a first guide101aof a conveyance path of a medium, and a surface of the second housing102facing the first housing101forms a second guide102aof the conveyance path.

The first medium sensor110is located on the loading tray103on the upstream side of the feed roller114and the separation roller115. The first medium sensor110detects whether a medium is located on the loading tray103. The first medium sensor110detects whether a medium is located on the loading tray103by a contact detection sensor passing predetermined current when being in contact with a medium or when not being in contact with a medium. The first medium sensor110generates and outputs a first medium signal with a signal value varying by whether a medium is located on the loading tray103. The first medium sensor110may be any other sensor, such as a light detection sensor, that can detect whether a medium is located on the loading tray103.

The passing sensor111is located on the upstream side of the separation roller115in the second housing102in the conveying direction A2and detects passing of a medium. In the example illustrated inFIG.2, the passing sensor111is located on the upstream side of the pick roller112. For example, the passing sensor111is a slit-type encoder. In this case, the passing sensor111includes a rotating member being provided with a slit and rotating with passing of a medium, a light emitting diode (LED), and a photodiode. Light pulses are generated by light emitted from the LED passing through the rotating slit. The passing sensor111generates and outputs a signal based on the widths or the interval of light pulses detected by the photodiode, i.e., a signal based on the moving speed of the medium, as a passing signal. For example, when the moving speed of a medium indicated by the passing signal is greater than or equal to a threshold value, the passing sensor111detects passing of the medium. The passing sensor111may be a magnetic encoder detecting a change in magnetism caused by rotation of a rotating member equipped with a magnet.

The pick roller112is located in the second housing102. The pick roller112comes in contact with a medium located on the loading tray103raised to a height almost identical to that of the conveyance path of a medium and feeds the medium toward the downstream side.

The lift sensor113is located inside the second housing102and on the downstream side of the pick roller112. The lift sensor113detects a lift of a medium fed by the pick roller112. A lift of a medium refers to a fed medium being curved toward the second housing102side with respect to the conveyance path. The lift sensor113detects a lift of a medium by generating and outputting a lift signal the signal value of which varies by whether the medium lifts. A structure of the lift sensor113will be described later by use ofFIG.3.

The feed roller114is located inside the second housing102and on the downstream side of the pick roller112. The feed roller114feeds a medium fed by the pick roller112further toward the downstream side. The separation roller115is located inside the first housing101in such a way as to face the feed roller114. The separation roller115is a so-called brake roller or a retard roller and can rotate in a direction opposite to the medium feeding direction or can stop. The feed roller114and the separation roller115separate media and feed one medium at a time. The feed roller114is located above the separation roller115, and the medium conveying apparatus100feeds media by a so-called top-first scheme. The feed roller114may be located below the separation roller115, and the medium conveying apparatus100may feed media by a so-called bottom-first scheme.

The second medium sensor116is located on the downstream side of the feed roller114and the separation roller115. The second medium sensor116detects a medium. The second medium sensor116is a recurrent prism sensor. The second medium sensor116includes a light emitting diode (LED) and a photodiode that are located inside the first housing101, and a prism located inside the second housing102. The prism is located in such a way as to face the LED and the photodiode with the conveyance path of a medium in between and to guide light from the LED to the photodiode. The second medium sensor116generates and outputs, as a second medium signal, a signal with a signal value being based on the intensity of light detected by the photodiode, i.e., a signal value varying by whether light projected from the LED is blocked by a medium. For example, when the second medium signal indicates that the light projected from the LED is blocked by a medium, the second medium sensor116detects the medium. The second medium sensor116may be any other sensor, such as a light detection sensor, that can detect a medium.

The first to fifth conveyance rollers117atoeand the first to fifth driven rollers118atoeare provided on the downstream side of the feed roller114and the separation roller115in such a way as to face each other, respectively. The first to fourth conveyance rollers117atodand the first to fourth driven rollers118atodconvey a medium fed by the feed roller114and the separation roller115toward the downstream side. The fifth conveyance roller117eand the fifth driven roller118eeject the medium conveyed by the first to fourth conveyance rollers117atodand the first to fourth driven rollers118atodonto the output tray104.

The imaging device119is located on the downstream side of the first conveyance roller117ain the conveying direction A2and images a medium conveyed by the first conveyance roller117aand the first driven roller118a. The imaging device119includes a first imaging device119aand a second imaging device119bthat are located in such a way as to face each other with the conveyance path of a medium in between. The first imaging device119aand the second imaging device119bare examples of an imaging unit.

The first imaging device119aincludes a line sensor based on a unity-magnification optical system type contact image sensor (CIS) including complementary metal oxide semiconductor-(CMOS-) based imaging elements linearly arranged in a main scanning direction. The first imaging device119afurther includes lenses each forming an image on the imaging elements, and an A/D converter amplifying and analog-digital (A/D) converting an electric signal output from the imaging elements. The first imaging device119agenerates an input image by imaging the front side of a conveyed medium and outputs the generated image.

Similarly, the second imaging device119bincludes a line sensor based on a unity-magnification optical system type CIS including CMOS-based imaging elements linearly arranged in the main scanning direction. The second imaging device119bfurther includes lenses each forming an image on the imaging elements, and an A/D converter amplifying and A/D converting an electric signal output from the imaging elements. The second imaging device119bgenerates an input image by imaging the back side of a conveyed medium and outputs the generated image.

The imaging device119may include only one of the first imaging device119aand the second imaging device119band read only one side of a medium. Each of the first imaging device119aand the second imaging device119bmay include a line sensor based on a unity-magnification optical system type CIS including charge coupled device-(CCD-) based imaging elements in locate of the line sensor based on a unity-magnification optical system type CIS including CMOS-based imaging elements. Each of the first imaging device119aand the second imaging device119bmay include a reduction optical system type line sensor including CMOS-based or CCD-based imaging elements.

A medium located on the loading tray103is conveyed between the first guide101aand the second guide102aalong the conveying direction A2by rotation of each of the pick roller112and the feed roller114in the feeding direction of the medium. As a feed mode of the medium conveying apparatus100, a user may set either of a separation mode of feeding a medium while separating the medium and a non-separation mode of feeding a medium without separation. The feed mode is set by the user operating the operation device105or an information processing device capable of communicating with the medium conveying apparatus100. When the feed mode is set to the separation mode, the separation roller115rotates in a direction opposite to the feeding direction of a medium or stops. Consequently, feed of a medium other than the separated medium is restricted, and multi feed is prevented. On the other hand, when the feed mode is set to the non-separation mode, the separation roller115rotates in the feeding direction of a medium.

A medium is conveyed between the first guide101aand the second guide102aby rotation of the first conveyance roller117ain the feeding direction of the medium. The medium is then fed to an imaging position of the imaging device119, and imaged by the imaging device119. The medium is further ejected onto the output tray104by rotation of each of the second to fifth conveyance rollers117btoein the feeding direction of the medium.

FIG.3is a perspective view of the lift sensor113. The lift sensor113includes an arm113aand a horseshoe-shaped sensor113b.

The arm113ais provided above the conveyance path of a medium in such a way as to extend in the medium conveying direction A2and is located in such a way that the bottom surface of the arm113afaces the first guide101aseparated by a predetermined distance. A plurality of lift sensors113may be spaced in the width direction A4. In this case, the arms113aare located at an identical height with respect to the first guide101a. A downstream-side edge113cof the arm113ais rotatably engaged with the second housing102in such a way that an upstream-side edge113dswings. Consequently, when a medium lifts, the medium comes in contact with the arm113aand raises the arm113aby rotating the arm113a. The distance between the bottom surface of the arm113aand the first guide101awhen a lift of a medium does not exist is appropriately set according to the magnitude of bending of a medium required to be detected by the lift sensor113.

The horseshoe-shaped sensor113bincludes a light-emitting element113e, a light-receiving element113f, and a connecting part113g. The connecting part113gconnects the light-emitting element113eto the light-receiving element113f. The light-emitting element113eand the light-receiving element113fare located in such a way as to face each other. The light-emitting element113eis an LED or the like and projects light toward the light-receiving element113f. The light-receiving element113fis a photodiode or the like. The light-emitting element113eand the light-receiving element113fare examples of a light-emitting unit and a light-receiving unit, respectively. The light-receiving element113fis provided in such a way as to face the light-emitting element113ewith the arm113ain between and detects light from the light-emitting element113e. The light-receiving element113fgenerates and outputs a lift detection signal being an electric signal based on the intensity of detected light. The horseshoe-shaped sensor113bis an example of a detector.

The arm113ais provided in such a way as to be located between the light-emitting element113eand the light-receiving element113fin an initial state and be located at a position not facing the light-emitting element113eand the light-receiving element113fin a raised state.

In other words, the arm113ais formed in such a way as to interrupt light from the light-emitting element113eto the light-receiving element113fin an unraised state and pass the light from the light-emitting element113eto the light-receiving element113fin the raised state. The horseshoe-shaped sensor113bgenerates, as a lift signal, a signal with a signal value being based on the intensity of light detected by the light-receiving element113f, i.e., a signal value varying by whether a fed medium lifts. For example, the lift sensor113detects a lift of a medium when the intensity of light detected by the light-receiving element113f, the intensity being indicated by the lift signal, is greater than or equal to a threshold value.

FIG.4is a diagram schematically illustrating placement of the lift sensors113and the second medium sensor116.FIG.4is a schematic diagram illustrating a positional relation between the lift sensors113and the second medium sensor116when the conveyance path is viewed from the top.

In the example illustrated inFIG.4, each of the two lift sensors113is located outside the pick roller112and the feed roller114in the width direction A4. Structures of the two lift sensors113are the same except that the structures are symmetric with respect to the width direction A4. The number of lift sensors113is not limited to two and may be one, or three or more.

The lift sensor113is located in such a way as to be separated from the pick roller112and the feed roller114by a predetermined distance in the width direction A4. The predetermined distance is set in such a way that when a medium with the shortest length in the width direction A4(such as an A5size) out of media likely to be bound by a staple, a clip, or the like is conveyed at the center in the width direction A4, an edge of the medium in the width direction A4passes below the arm113a. Consequently, when a bound medium bound by a staple, a clip, or the like is conveyed, the lift sensor113can reliably detect a lift of the medium.

The upstream edge113dof the arm113aof the lift sensor113is positioned on the upstream side of the upstream edge of a roller nip112aof the pick roller112. The downstream edge113cof the arm113aof the lift sensor113is positioned on the downstream side of the downstream edge of a roller nip114aof the feed roller114and the separation roller115. Consequently, the lift sensor113detects a lift of a medium between the upstream edge of the roller nip112aof the pick roller112and the downstream edge of the roller nip114aof the feed roller114and the separation roller115.

The second medium sensor116is located on the downstream side of the separation roller115. The second medium sensor116is located between the two separation rollers115and, for example, is located at the center in the width direction A4. A plurality of second medium sensors116may be spaced along the width direction A4.

FIG.5is a block diagram illustrating an example of a schematic configuration of the medium conveying apparatus100. In addition to the configuration described above, the medium conveying apparatus100further includes a motor131, an interface device132, a storage device140, and a processing circuit150.

The motor131includes one or a plurality of motors. The motor131feeds and conveys a medium by rotating the pick roller112, the feed roller114, the separation roller115, and the first to fifth conveyance rollers117atoein accordance with control pulses from the processing circuit150. The first to fifth driven rollers118atoemay be rotated by the motor131instead of being driven according to rotation of each conveyance roller.

The interface device132includes an interface circuit conforming to a serial bus such as USB. The interface device132is electrically connected to an unillustrated information processing device (such as a personal computer or a mobile information terminal) and transmits and receives various types of information including an input image. The medium conveying apparatus100may include a communication unit including an antenna transmitting and receiving wireless signals and a communication interface circuit for transmitting and receiving signals through a wireless communication line in locate of the interface device132. For example, a communication protocol used by the communication interface circuit is a wireless local area network (LAN).

The storage device140includes a memory such as a random-access memory (RAM) or a read-only memory (ROM), a fixed disk device such as a hard disk, or a portable storage device such as a flexible disk or an optical disk. The storage device140stores a computer program, a database, a table, and the like that are used for various types of processing in the medium conveying apparatus100. The computer program may be installed on the storage device140from a computer-readable and non-transitory portable storage medium by use of a known setup program or the like. Examples of the portable storage medium include a compact disc read-only memory (CD-ROM) and a digital versatile disc read-only memory (DVD-ROM).

The processing circuit150operates in accordance with a program previously stored in the storage device140. For example, the processing circuit150is a central processing unit (CPU). Examples of the processing circuit150may also include a digital signal processor (DSP), a large-scale integration (LSI), an application specific integrated circuit (ASIC), and a field-programmable gate array (FPGA).

The processing circuit150is connected to the operation device105, the display device106, the first medium sensor110, the passing sensor111, the lift sensor113, the second medium sensor116, the imaging device119, the motor131, the interface device132, the storage device140, and the like and controls these components. The processing circuit150conveys a medium by controlling the motor131, acquires an input image by controlling the imaging device119, and transmits the acquired input image to the information processing device through the interface device132. Further, the processing circuit150determines whether a conveyed medium is a bound medium, based on a passing signal received from the passing sensor111, a lift detection signal received from the lift sensor113, and a second medium signal received from the second medium sensor116.

FIG.6is a diagram illustrating schematic configurations of the storage device140and the processing circuit150.

Programs such as a control program141and a determination program142are stored in the storage device140. Each program is a functional module implemented by software operating on a processor. The processing circuit150functions as a control unit151and a determination unit152by reading each program stored in the storage device140and operating in accordance with the read program.

FIG.7is a flowchart illustrating a flow of operation of medium conveyance processing executed by the medium conveying apparatus100. The medium conveyance processing is achieved by cooperation between the processing circuit150and the components in the medium conveying apparatus100in accordance with a program stored in the storage device140.

First, the control unit151stands by until an operation signal providing an instruction to read a medium is received (S101). The operation signal is fed to the control unit151from the operation device105in response to input of a read instruction of a medium to the operation device105by a user. The operation signal may be fed from the information processing device through the interface device132in response to input of a read instruction to the information processing device by the user.

Next, the control unit151determines whether a medium is located on the loading tray103, based on a first medium signal output from the first medium sensor110(S102). When a medium is not located (S102: No), the medium conveyance processing ends.

When a medium is located (S102: Yes), the control unit151raises the loading tray103to a position allowing feed of the medium by driving a motor for moving the loading tray103. The control unit151feeds and conveys the medium located on the loading tray103by rotating the pick roller112, the feed roller114, the separation roller115, and the first to fifth conveyance rollers117atoe by driving the motor131(S103).

Next, the control unit151determines whether the medium is detected by the second medium sensor116, based on a second medium signal output from the second medium sensor116(S104). When the second medium signal indicates that light projected from the LED is blocked by the medium, the control unit151determines that the front edge of the medium has arrived at the position of the second medium sensor116and that the medium is detected by the second medium sensor116. When the medium is not detected by the second medium sensor116(S104: No), the control unit151returns to S104and stands by until the medium is detected by the second medium sensor116.

When the medium is detected by the second medium sensor116(S104: Yes), the determination unit152executes determination processing of imaging the medium while determining whether the medium is a bound medium (S105). Details of the determination processing will be described later.

Next, the control unit151determines whether conveyance of the medium is stopped when the determination processing ends (S106). When conveyance of the medium is stopped (S106: Yes), the medium conveyance processing ends.

When conveyance of the medium is continued (S106: No) and the medium is determined to be located on the loading tray103, based on the first medium signal output from the first medium sensor110(S107: Yes), the medium conveyance processing returns to S104, and the control unit151stands by until a next medium is detected by the second medium sensor116. When a medium is not located (S107: No), the control unit151ends the medium conveyance processing by stopping the motor131.

FIG.8is a flowchart illustrating a flow of the determination processing executed by the medium conveying apparatus100in S105in the medium conveyance processing. In the determination processing, whether a medium is a bound medium, a small-sized rear-edge-curled medium, or another medium is determined. Then, conveyance is stopped in response to a user operation when the medium is determined to be a bound medium, and conveyance is continued when the medium is determined to be a medium other than a bound medium. A small-sized medium refers to a medium (such as an A5size) the width of which in the conveying direction A2of a medium is smaller than that of a standard-sized medium (such as an A4size). A rear-edge-curled medium refers to a medium the upstream-side edge of which is curved toward the second housing102side. Rear-edge-curled media also include a medium bent toward the second housing102side in addition to a medium the upstream-side edge of which is curved toward the second housing102side.

In the determination processing, whether a medium is a bound medium is continuously determined in a determination period from arrival of the front edge of the medium at the second medium sensor116until the medium is further conveyed by a predetermined distance. When the front edge of the medium arrives at an imaging start position before the determination period ends, the medium is imaged in parallel with the determination. The predetermined distance is set to a value greater than the distance from the second medium sensor116to the imaging start position. In other words, the predetermined distance is set in such a way that imaging of the medium is started after the determination period is started and before the determination period ends.

First, the determination unit152starts timekeeping of the determination period (S201). The determination period is a period from arrival of a medium at the second medium sensor116until the medium is further conveyed by the predetermined distance. In this case, the determination unit152starts counting of control pulses fed to the motor131driving the first to fifth conveyance rollers117atoe. The determination period may be a period from arrival of a medium at the second medium sensor116until a predetermined amount of time elapses. In this case, the determination unit152starts measurement of the amount of time elapsed from the time of arrival of the medium at the second medium sensor116.

Next, the determination unit152determines whether a lift of the medium is detected by the lift sensor113, based on a lift signal output by the lift sensor113(S202). When the intensity of light detected by the light-receiving element113f, the intensity being indicated by the lift signal, is greater than or equal to the threshold value, the determination unit152determines that a lift of the medium is detected.

When a lift of the medium is detected by the lift sensor113(S202: Yes), the determination unit152determines whether passing of the medium is detected by the passing sensor111, based on a passing signal output by the passing sensor111(S203). When the moving speed of the medium indicated by the passing signal is greater than or equal to the threshold value, the determination unit152determines that passing of the medium is detected by the passing sensor111.

When passing of the medium is detected by the passing sensor111(S203: Yes), the determination unit152determines that the medium is a bound medium, and the control unit151temporarily stops conveyance of the medium by stopping the motor131(S204). In other words, when a lift of the medium is detected by the lift sensor113and passing of the medium is detected by the passing sensor111during the determination period, the determination unit152determines that the medium is a bound medium. The control unit151may display a warning on the display device106. Stopping of conveyance of a medium and display of a warning are examples of execution of abnormality control.

When passing of the medium is not detected by the passing sensor111(S203: No), the determination unit152determines that the medium is a small-sized rear-edge-curled medium, and the control unit151images the medium by controlling the imaging device119(S205). Small-sized refers to the width of a medium in the medium conveying direction A2being small, and a rear-edge-curled medium refers to a medium the upstream-side edge of which is bent upward. In other words, when a lift of the medium is detected by the lift sensor113and passing of the medium is not detected by the passing sensor111during the determination period, the determination unit152determines that the medium is a small-sized rear-edge-curled medium.

When the medium is determined to be a small-sized rear-edge-curled medium by the determination unit152, the control unit151stands by until the medium arrives at the imaging start position. For example, the imaging start position is positioned between the position of the second medium sensor116and the position of the imaging device119. In this case, when the medium is conveyed by the distance between the second medium sensor116and the imaging start position after the medium is detected by the second medium sensor116, the control unit151determines that the medium has arrived at the imaging start position. When the medium arrives at the imaging start position, the control unit151acquires input images by sequentially imaging the medium from the downstream side of the medium with conveyance of the medium by controlling the imaging device119. The control unit151transmits the acquired input images to the information processing device through the interface device132. The above concludes the determination processing. In other words, when a medium is determined to be a small-sized rear-edge-curled medium, the determination processing ends in a state of conveyance of the medium being continued.

When imaging of the medium is started in S212to be described later before the medium is determined to be a small-sized rear-edge-curled medium in S205, the control unit151continues imaging of the medium and acquires input images.

A principle of determining whether a medium is a bound medium or a small-sized rear-edge-curled medium will be described below.

FIG.9Ais a schematic side view of a bound medium arriving at the position of the feed roller114and the separation roller115, andFIG.9Bis a schematic plan view of the bound medium. In the example illustrated inFIG.9A, the bound medium is acquired by binding a lower-side medium M1and an upper-side medium M2by a binding part S. When the bound medium arrives at the position of the feed roller114and the separation roller115, the lower-side medium M1stops by rotation of the separation roller115, and only the upper-side medium M2attempts to progress in the medium conveying direction A2by rotation of the feed roller114. At this time, since the front edge of the upper-side medium M2is fixed to the lower-side medium M1by the binding part S, a lift occurs between a region T of the upper-side medium M2in contact with the feed roller114and the binding part S.

FIG.10Ais a schematic side view of a normal medium (referring to a medium other than a bound medium and a rear-edge-curled medium) in the determination period. When a normal medium is conveyed, the lift sensor113does not detect a lift of the determination period, and the passing sensor111detects passing of the medium.

FIG.10Bis a schematic side view of a bound medium in the determination period. As described above, a lift occurs in a bound medium at the position of the feed roller114and the separation roller115. Accordingly, when a bound medium is conveyed, the lift sensor113detects a lift in the determination period, and the passing sensor111detects passing of the medium at a point in time when the lift is detected.

FIG.11Ais a schematic side view of a small-sized rear-edge-curled medium in the determination period. When a small-sized medium is conveyed, the rear edge of the medium completes passing the passing sensor111and the pick roller112and arrives at the position of the lift sensor113in the determination period. Further, the rear edge of a rear-edge-curled medium rises after passing the pick roller112and pushes up the lift sensor113. Accordingly, when a small-sized rear-edge-curled medium is conveyed, the lift sensor113detects a lift in the determination period, and the passing sensor111does not detect passing of the medium at a point in time when the lift is detected.

FIG.11Bis a schematic side view of a regular-sized rear-edge-curled medium in the determination period. When a regular-sized rear-edge-curled medium is conveyed, the rear edge of the medium does not arrive at the position of the lift sensor113in the determination period, and therefore the lift sensor113does not detect a lift.

In other words, by setting the length of the determination period in such a way that the determination period ends before the rear edge of a regular-sized medium arrives at the position of the lift sensor113, a bound medium and a regular-sized rear-edge-curled medium can be distinguished, based on a detection result of the lift sensor113. However, a detection result of the lift sensor113alone does not allow distinction between a bound medium and a small-sized rear-edge-curled medium. Further use of a detection result of the passing sensor111enables distinction between a bound medium and a small-sized rear-edge-curled medium.

Returning toFIG.8, after the medium is determined to be a bound medium in S204, the control unit151determines whether imaging of the medium is started by the imaging device119(S206). Since the imaging start position is positioned on the downstream side of the second medium sensor116, it is determined that imaging by the imaging device119is not started immediately after arrival of the medium at the second medium sensor116. However, as will be described later, the determination unit152continuously determines whether the medium is a bound medium throughout a period before the start of imaging of the medium to after the start. Accordingly, it may be determined that imaging by the imaging device119is started depending on a timing of occurrence of a lift of the medium.

When imaging of the medium is started (S206: Yes), the control unit151displays a screen for instructing the user to remove the medium from the inside of the medium conveying apparatus100on the display device106(S207). The above concludes the determination processing. In other words, when the medium is determined to be a bound medium and imaging of the medium is started, the determination imaging processing ends in a state of conveyance of the medium being stopped.

When imaging of the medium is not started (S206: No), the control unit151displays a screen for accepting user selection of whether to continue conveyance of the medium on the display device106(S208).

Next, the control unit151determines whether the user operation on the operation device105is an instruction to continue conveyance of the medium (S209). When the operation is not an instruction to continue conveyance of the medium (S209: No), the control unit151displays a screen for instructing the user to remove the medium from the inside of the medium conveying apparatus100on the display device106(S207). The above concludes the determination processing.

When the operation is an instruction to continue conveyance of the medium (S209: Yes), the control unit151conveys the medium by driving the motor131(S210).

After S210, or when a lift of a medium is not detected in S202(S202: No), the control unit151determines whether the medium has arrived at the imaging start position for the first time (S211). When imaging of the medium is not started and the medium has arrived at the imaging start position, the control unit151determines that the medium has arrived at the imaging start position for the first time. When imaging of the medium is already started or when the medium has not arrived at the imaging start position (S211: No), the determination processing advances to S202.

When the medium has arrived at the imaging start position for the first time (S211: Yes), the control unit151starts imaging of the medium by controlling the imaging device119(S212). From then onward, the control unit151sequentially images the medium from the downstream side of the medium with conveyance of the medium.

Next, the determination unit152determines whether the determination period has ended (S213). For example, the determination unit152determines whether the determination period has ended, based on the number of control pulses fed to the motor131after detection of the medium by the second medium sensor116.

When the determination period has not ended (S213: No), the determination processing advances to S202. In this case, whether a lift of the medium and passing of the medium are detected is determined in parallel with imaging of the medium in the remaining determination period.

When the determination period has ended (S213: Yes), the determination unit152determines that the medium is not a small-sized rear-edge-curled medium or a bound medium and continues imaging of the medium (S214). The determination unit152ending imaging of the medium and acquiring input images transmits the acquired input images to the information processing device through the interface device132. The above concludes the determination processing.

As described above, when a lift of a medium is detected by the lift sensor113located on the downstream side of the separation roller115and passing of the medium is detected by the passing sensor111located on the upstream side of the separation roller115in the determination period, the medium conveying apparatus100determines that the medium is a bound medium. Consequently, a bound medium and a small-sized rear-edge-curled medium are distinguished, and therefore the medium conveying apparatus100enables more precise detection of a medium on which abnormality control is to be executed.

Further, the medium conveying apparatus100accepts user selection of whether to continue conveyance of a medium when imaging of the medium is not started at the point in time when the medium is determined to be a bound medium and stops conveyance of the medium when imaging of the medium is not started. In other words, acceptance of user selection at the point in time when a medium is determined to be a bound medium enables saving of time and effort for the user to locate the medium on the loading tray103again when a medium not being a bound medium is erroneously determined to be a bound medium. However, normal input images are not acquired when imaging of the medium started at the point in time when conveyance is temporarily stopped, and therefore the user needs to locate the medium on the loading tray103again regardless of whether the determination is erroneous. With the aforementioned configuration, the medium conveying apparatus100can save time and effort for the user to locate the medium again and time and effort for the user to select whether to continue conveyance of the medium, thereby enabling improved convenience for the user.

While the determination processing advances to S210when the operation is an instruction to continue conveyance of the medium in S209in the determination processing in the aforementioned description, the processing is not limited to such an example. For example, when the user operation is an instruction to continue conveyance of the medium, the determination processing may advance to S205or S214, image the medium, and end the determination processing. In other words, when the user operation is an instruction to continue conveyance of the medium, the medium conveying apparatus100may not determine whether the medium is a bound medium from then onward.

For example, when the user operation is an instruction to continue conveyance of the medium, the determination processing may advance to S205or S214, image the medium, and end the determination processing. For example, when the medium is determined to be a bound medium in S204, the determination unit152may display a screen for accepting selection of whether to continue conveyance of the medium regardless of whether imaging of the medium is started on the display device106. Such processing can still save time and effort for the user to locate the medium again, thereby enabling improved convenience for the user.

While the passing sensor111is assumed to be a slit-type encoder or a magnetic encoder in the aforementioned description, the sensor is not limited to such an example. For example, the passing sensor111may detect passing of a medium, based on electromotive force caused by a driven roller rotating according to movement of the medium along the conveying direction A2. In this case, the passing sensor111includes a driven roller and a conversion circuit generating voltage based on the rotation speed of the driven roller. The conversion circuit includes a motor rotating with rotation of the driven roller and generating voltage based on the rotation speed, and a peripheral circuit and outputs, as a passing signal, a signal the value of which varies by the generated voltage. For example, when voltage indicated by the passing signal is greater than or equal to a threshold value, the passing sensor111detects passing of a medium.

FIG.12is a diagram illustrating a conveyance path inside a medium conveying apparatus200according to another embodiment. The medium conveying apparatus200differs from the medium conveying apparatus100in including a second housing202, a passing sensor211, and a lift sensor213in locate of the second housing102, the passing sensor111, and the lift sensor113.

The second housing202includes a second guide202alocated above a conveyance path of a medium. The second guide202ais formed in such a way as to be almost parallel with a first guide101a. Further, a recessed part202bdepressed upward is formed on the second guide202abetween a separation roller115and a first conveyance roller117a.

The passing sensor211is located on the upstream side of the separation roller115and on the downstream side of a pick roller112and detects passing of a medium. A structure of the passing sensor211is similar to the structure of the passing sensor111.

FIG.13is a schematic diagram illustrating a structure of the lift sensor213. The lift sensor213is located above the conveyance path of a medium and in the recessed part202bformed between the separation roller115and the first conveyance roller117a. The lift sensor213includes an ultrasonic transmitter213aand an ultrasonic receiver213b.

The ultrasonic transmitter213ais located on the side of the recessed part202band outputs an ultrasonic wave along a conveying direction A2of a medium. The ultrasonic receiver213bis located in such a way as to face the ultrasonic transmitter213aand receives an ultrasonic wave output by the ultrasonic transmitter213a. The ultrasonic receiver213boutputs a signal based on the intensity of the received ultrasonic wave as a lift signal.

When a lift of a medium does not occur, the ultrasonic receiver213bdirectly receives an ultrasonic wave output by the ultrasonic transmitter213a. When a lift of a medium occurs, the ultrasonic receiver213breceives an ultrasonic wave being output by the ultrasonic transmitter213aand passing through the lifting medium. Since the ultrasonic wave attenuates when passing through a medium, a lift of a medium can be detected, based on the intensity of the ultrasonic wave received by the ultrasonic receiver213b.

Since the ultrasonic transmitter213aand the ultrasonic receiver213bdo not come in contact with a lifting medium, mechanical degradation such as abrasion is not likely to occur, thereby holding down man-hours and costs of maintenance. Accordingly, by inclusion of the lift sensor213, the medium conveying apparatus200enables improved maintainability.

Further, formation of the recessed part202bon the second guide202aavoids a lift of a medium being hindered by the second guide202a. Accordingly, the medium conveying apparatus200enables more precise detection of a lift of a medium.

FIG.14is a diagram illustrating a conveyance path inside a medium conveying apparatus300according to another embodiment. The medium conveying apparatus300differs from the medium conveying apparatus100in including a second housing302, a passing sensor311, and a lift sensor313in locate of the second housing102, the passing sensor111, and the lift sensor113.

The second housing302includes a second guide302alocated above a conveyance path of a medium. The second guide302ais formed in such a way as to be almost parallel with a first guide101a. Further, a recessed part302bdepressed upward is formed on the second guide302aon the upstream side of a separation roller115.

The passing sensor311is located on the upstream side of the separation roller115and on the downstream side of a pick roller112in such a way that the recessed part302bis located between the sensor and the separation roller115, and detects passing of a medium. A structure of the passing sensor311is similar to the structure of the passing sensor111.

FIG.15is a schematic diagram illustrating a structure of a lift sensor313. The lift sensor313is located above the conveyance path of a medium and in a recessed part302bformed between the passing sensor311and the separation roller115. The lift sensor313includes a light emitter313abeing an LED and a light receiver313bbeing a photodiode.

The light emitter313ais located at the bottom of the recessed part302band projects light downward. The light receiver313bis located at the bottom of the recessed part302band receives light being projected from the light emitter313aand being reflected by a medium. The light receiver313boutputs, as a lift signal, a signal indicating a value varying by the time between projection of light by the light emitter313aand reception of the light by the light receiver313b. For example, the lift sensor313detects a lift of a medium when the time between projection of light by the light emitter313aand reception of the light by the light receiver313b, the time being indicated by the lift signal, is less than or equal to a threshold value.

When a lift of a medium occurs, the distance between the light emitter313aand the light receiver313b, and the medium shortens compared with a case of a lift of the medium not occurring, and therefore the time between projection of light by the light emitter313aand reception of the light by the light receiver313bshortens. Accordingly, a lift of a medium can be detected, based on the time between projection of light by the light emitter313aand reception of the light by the light receiver313b.

Since the light emitter313aand the light receiver313bdo not come in contact with a lifting medium, mechanical degradation such as abrasion is not likely to occur, thereby holding down man-hours and costs of maintenance. Accordingly, by inclusion of the lift sensor313, the medium conveying apparatus300can enable improved maintainability.

Further, the lift sensor313is located on the upstream side of the separation roller115. Consequently, the medium conveying apparatus300can detect a lift of a medium shortly after a bound medium arrives at the separation roller115and separation of the medium starts. Accordingly, the medium conveying apparatus300enables as much prevention of damage to a bound medium caused by an attempt to separate the medium as possible.

Various embodiments described above may be appropriately implemented in combination. For example, the lift sensor213may be located in the recessed part302b.

FIG.16is a diagram illustrating a schematic configuration of a processing circuit450in a medium conveying apparatus according to another embodiment. The processing circuit450is used in locate of the processing circuit150in the medium conveying apparatus100and executes the medium reading processing. The processing circuit450includes a control circuit451and a determination circuit452. Each of the components may be independently configured with an integrated circuit, a microprocessor, firmware, or the like.

The control circuit451is an example of a control unit and has a function similar to that of the control unit151. The control circuit451receives an operation signal from an operation device105, a first medium signal from a first medium sensor110, and a determination result in the determination processing from the determination circuit452and controls a motor131, based on the received signals and the received determination result. Further, the control circuit451receives an input image from an imaging device119and transmits the image to an information processing device through an interface device132.

The determination circuit452is an example of a determination unit and has a function similar to that of the determination unit152. The determination circuit452receives a passing signal, a lift detection signal, and a second medium signal from a passing sensor111, a lift sensor113, and a second medium sensor116, respectively. The determination circuit452determines whether a medium is a bound medium, or the like, based on the received signals and outputs the determination result to the control circuit451.

As described above, the medium conveying apparatus enables suitable detection of a bound medium when the processing circuit450is used as well.

The medium conveying apparatus, medium conveying method, and computer program can precisely detect a medium on which abnormality control is to be executed.