WO2023218562A1

WO2023218562A1 - Medium feed device, medium feed method, and control program

Info

Publication number: WO2023218562A1
Application number: PCT/JP2022/019957
Authority: WO
Inventors: 修一森川; 喜一郎下坂
Original assignee: 株式会社Pfu
Priority date: 2022-05-11
Filing date: 2022-05-11
Publication date: 2023-11-16

Abstract

Provided are a medium feed device, a medium feed method, and a control program that make it possible to appropriately reduce the occurrence of multi-feed of media. The medium feed device comprises a stage, a feed roller that sequentially feeds a plurality of media placed on the stage, a separation roller facing the feed roller, a detection unit that detects the front end position of the media at a nip part between the feed roller and the separation roller, and a setting unit that sets a characteristic value of the separation roller. The setting unit changes the characteristic value according to the inter-medium distance between the front end position of a preceding medium and the front end position of the medium next to the preceding medium detected by the detection unit in the nip part.

Description

Media feeding device, media feeding method and control program

The present disclosure relates to a medium feeding device, a medium feeding method, and a control program, and particularly relates to a medium feeding device having a feeding roller and a separation roller, a medium feeding method, and a control program.

In a medium transport device such as a scanner that separates and sequentially feeds multiple media to capture images, it is required to suppress the occurrence of multi-feeding of media in which multiple media are fed together.

Disclosed is a paper feeding device that includes a sheet number sensor that detects the number of sheets at or downstream of the nip between a conveyance roller and a separation roller, and a sheet position sensor that detects the position of the sheet that has come out downstream from the nip. (See Patent Document 1). This paper feeding device controls the pressure load or separation torque of the separation roller so that when two sheets are detected by the sheet number sensor, the position of the second sheet detected by the sheet position sensor becomes a target value. .

A sheet conveyance device has been disclosed that separates sheets double-fed from a sheet bundle and conveys them one by one at a handling nip between a paper feed roller and a handling roller (see Patent Document 2). This sheet conveying device captures an image of the next sheet separated by the separating roller using an area sensor, and detects the leading edge from the image data to obtain the amount of protrusion of the leading edge of the next sheet from the handling nip. The sheet conveying device determines the deterioration state of the handling roller based on the amount of protrusion of the next sheet, and displays a warning in accordance with the determination result.

A feeding rotary body that feeds the sheet placed on the loading section, a size detection means that detects the size of the sheet in the width direction, and detects the leading edge of the sheet passing through the nip area between the first member and the second member. A sheet feeding device is disclosed that has a leading end detection means (see Patent Document 3). This sheet feeding device detects the sheet size detected by the size detection means, and when the sheet fed by the feeding rotary body passes through the detection area of the leading edge detection means, the feeding rotary body Move to the evacuation position. If the sheet to be fed does not pass through the detection area, the sheet feeding device moves the feeding rotary body to the retracted position after a predetermined period of time has elapsed since the feeding of the sheet by the feeding rotary body started.

Japanese Patent Application Publication No. 2005-350239 Japanese Patent Application Publication No. 2016-104663 JP 2017-1878 Publication

A media feeding device is required to appropriately suppress the occurrence of double feeding of media.

The purpose of the medium feeding device, medium feeding method, and control program according to the embodiment is to appropriately suppress the occurrence of double feeding of media.

A medium feeding device according to one aspect of the embodiment includes a mounting table, a feeding roller that sequentially feeds a plurality of media placed on the mounting table, and a separation roller disposed opposite to the feeding roller. , a detection unit that detects the position of the leading edge of the medium in the nip between the feeding roller and the separation roller, and a setting unit that sets the characteristic value of the separation roller, and the setting unit includes a detection unit that detects the position of the leading edge of the medium in the nip between the feeding roller and the separation roller, and a setting unit that sets the characteristic value of the separation roller. The characteristic value is changed depending on the inter-medium distance between the leading edge position of the preceding medium and the leading edge position of the medium following the preceding medium.

A medium feeding method according to one aspect of the embodiment includes a feeding roller that sequentially feeds a plurality of media placed on a mounting table, and a feeding roller and a separation roller disposed opposite the feeding roller. detecting a leading edge position of a medium in a nip portion of the media and setting a characteristic value of a separating roller; The characteristic value is changed depending on the distance between the media and the position.

A control program according to one aspect of the embodiment includes a mounting table, a feeding roller that sequentially feeds a plurality of media placed on the mounting table, and a separation roller arranged opposite to the feeding roller. A control program for a medium feeding device comprising: detecting a leading edge position of a medium at a nip portion between a feeding roller and a separating roller; , the characteristic value is changed depending on the inter-medium distance between the leading edge position of the preceding medium detected within the nip and the leading edge position of the medium following the preceding medium.

According to this embodiment, the medium feeding device, the medium feeding method, and the control program can appropriately suppress the occurrence of double feeding of media.

The objects and advantages of the invention will be realized and obtained by means of the elements and combinations particularly pointed out in the claims. Both the foregoing general description and the following detailed description are intended to be exemplary and explanatory and are not intended to limit the invention as claimed.

FIG. 1 is a perspective view showing a medium feeding device 100 according to an embodiment. FIG. 3 is a diagram for explaining a conveyance path inside the medium feeding device 100. FIG. FIG. 2 is a schematic diagram for explaining a first imaging device 115 and the like. 3 is a schematic diagram for explaining a drive mechanism 130. FIG. 1 is a block diagram showing a schematic configuration of a medium feeding device 100. FIG. 1 is a diagram showing a schematic configuration of a storage device 150 and a processing circuit 160. FIG. 3 is a flowchart illustrating an example of the operation of a medium reading process. 3 is a flowchart illustrating an example of the operation of setting processing. (A) and (B) are schematic diagrams showing an example of an input image. (A) and (B) are schematic diagrams showing an example of an input image. 7 is a flowchart illustrating another example of the operation of setting processing. 7 is a flowchart illustrating another example of the operation of setting processing. (A) and (B) are schematic diagrams showing an example of the second input image. 3 is a diagram showing a schematic configuration of another processing circuit 260. FIG.

Hereinafter, a medium feeding device, a medium feeding method, and a control program according to one aspect of the present disclosure will be described with reference to the drawings. However, it should be noted that the technical scope of the present invention is not limited to these embodiments, but extends to the invention described in the claims and equivalents thereof.

FIG. 1 is a perspective view showing a medium feeding device 100 configured as an image scanner. The medium feeding device 100 feeds and conveys a medium, which is a document, and images the medium. The medium is paper, thin paper, cardboard, card, booklet, or the like. The medium feeding device 100 may be a facsimile, a copying machine, a multifunction peripheral (MFP), or the like. Note that the medium to be conveyed may be an object to be printed instead of a document, and the medium feeding device 100 may be a printer or the like.

The medium feeding device 100 includes a lower housing 101, an upper housing 102, a mounting table 103, a discharge table 104, an operating device 105, a display device 106, and the like. In FIG. 1, arrow A1 indicates the medium transport direction, arrow A2 indicates the width direction perpendicular to the medium transport direction, and arrow A3 indicates the height direction perpendicular to the medium transport path. In the following, upstream refers to upstream in the medium transport direction A1, and downstream refers to downstream in the medium transport direction A1.

The upper housing 102 is disposed at a position covering the upper surface of the medium feeding device 100, and is engaged with the lower housing 101 by a hinge so that it can be opened and closed when a medium becomes clogged or when cleaning the inside of the medium feeding device 100. are doing.

The mounting table 103 engages with the lower casing 101 and places the medium to be fed and transported. The ejection table 104 engages with the upper housing 102 and places the ejected medium thereon. Note that the ejection table 104 may be engaged with the lower housing 101.

The operating device 105 includes an input device such as a button and an interface circuit that obtains a signal from the input device, receives an input operation by a user, and outputs an operation signal according to the input operation by the user. The display device 106 has a display including a liquid crystal, an organic EL (Electro-Luminescence), etc., and an interface circuit that outputs image data to the display, and displays the image data on the display.

FIG. 2 is a diagram for explaining the transport path inside the medium feeding device 100.

The conveyance path inside the medium feeding device 100 includes a first medium sensor 111, a feeding roller 112, a separating roller 113, a light source device 114, a first imaging device 115, a pressing mechanism 116, a second medium sensor 117, and a first conveying roller. 118, a first driven roller 119, a third medium sensor 120, a second imaging device 121, a second conveyance roller 122, a second driven roller 123, and the like.

Note that the number of each of the feeding roller 112, separation roller 113, first conveying roller 118, first driven roller 119, second conveying roller 122 and/or second driven roller 123 is not limited to one, and may be plural. good. In that case, the plurality of feeding rollers 112, separation roller 113, first conveying roller 118, first driven roller 119, second conveying roller 122 and/or second driven roller 123 are moved in the width direction perpendicular to the medium conveying direction. They are arranged side by side at intervals on A2.

The upper surface of the lower casing 101 forms a lower guide 101a for the medium transport path, and the lower surface of the upper casing 102 forms an upper guide 102a for the medium transport path. The medium feeding device 100 has a so-called straight path, and sequentially feeds and conveys the medium placed on the mounting table 103 from the bottom, and discharges it onto the discharge table 104.

The first medium sensor 111 is arranged upstream of the feeding roller 112 and separation roller 113. The first medium sensor 111 includes a contact detection sensor and detects whether a medium is placed on the mounting table 103. The first medium sensor 111 generates and outputs a first medium signal whose signal value changes depending on whether a medium is placed on the mounting table 103 or not. Note that the first medium sensor 111 is not limited to a contact detection sensor, and any other sensor capable of detecting the presence or absence of a medium, such as a photodetection sensor, may be used as the first medium sensor 111.

The feeding roller 112 is provided in the lower housing 101. The feeding roller 112 is rotatably provided in the medium feeding direction A4, and sequentially separates and feeds a plurality of media placed on the mounting table 103 from the bottom. The separation roller 113 is a so-called brake roller or retard roller, and is provided in the upper housing 102 and is disposed opposite to the feeding roller 112. The separation roller 113 is provided rotatably or stopably in a direction A5 opposite to the medium feeding direction.

The pressing mechanism 116 is an example of a pressing section, and presses the separation roller 113 toward the feeding roller 112 side. The pressing mechanism 116 is provided so that the pressing force for pressing the separation roller 113 toward the feeding roller 112 can be adjusted. The pressing mechanism 116 includes an elastic member 116a, a support member 116b, a drive device 116c, and the like.

The elastic member 116a is, for example, a spring member such as a torsion coil spring. Note that the elastic member 116a may be another spring member such as a compression coil spring, a rubber member, or the like. One end of the elastic member 116a is attached to the support member 116b, and the other end is attached to the shaft 113a of the separation roller 113. The elastic member 116a presses the separation roller 113 toward the feeding roller 112 side.

The support member 116b is provided to support the elastic member 116a. The support member 116b is provided so as to be movable according to the driving force generated by the driving device 116c.

The drive device 116c is, for example, a solenoid. Note that the drive device 116c may be a motor or the like. The driving device 116c generates a driving force for adjusting the pressing force for pressing the separation roller 113 toward the feeding roller 112 by the elastic member 116a, based on a control signal from a processing circuit described later. When the drive device 116c is a solenoid, the support member 116b slides according to the linear movement of the movable magnetic pole of the solenoid, and adjusts the pressing force by the elastic member 116a. When the drive device 116c is a motor, the support member 116b swings according to the rotation of the motor to adjust the pressing force exerted by the elastic member 116a. Note that when the drive device 116c is a motor, a rack and a pinion are provided between the drive device 116c and the support member 116b, and the support member 116b slides according to the rotation of the motor to adjust the pressing force by the elastic member 116a. It's okay.

The second medium sensor 117 is disposed downstream of the feeding roller 112 and upstream of the first conveyance roller 118, and detects the medium conveyed to that position. The second medium sensor 117 includes a light emitter and a light receiver provided on one side with respect to the medium transport path, and a light guide tube provided at a position facing the light emitter and the light receiver across the medium transport path. including. The light emitting device is an LED (Light Emitting Diode) or the like, and emits light toward the medium transport path. On the other hand, the light receiver is a photodiode or the like, and receives the light emitted by the light emitter and guided by the light guide tube. When a medium exists at a position facing the second medium sensor 117, the light emitted from the light emitter is blocked by the medium, so the light receiver does not detect the light emitted from the light emitter. The second medium sensor 117 generates a second medium signal whose signal value changes depending on whether the medium is present at the position of the second medium sensor 117 or not, based on the intensity of the light received by the light receiver. and output it.

Note that a reflective member such as a mirror may be used instead of the light guide tube. Further, the light emitter and the light receiver may be provided facing each other with the medium transport path in between. Further, the second medium sensor 117 may detect the presence of the medium using a contact detection sensor or the like that flows a predetermined current when the medium is in contact or not in contact with the medium.

The first conveyance roller 118 and the first driven roller 119 are arranged facing each other on the downstream side of the feed roller 112 and the separation roller 113 in the medium conveyance direction A1. The first conveyance roller 118 is provided in the upper housing 102 and conveys the medium fed by the feed roller 112 and separation roller 113 to the second imaging device 121. Note that the first conveyance roller 118 may be provided in the lower casing 101 and the first driven roller 119 may be provided in the upper casing 102.

The third medium sensor 120 is disposed downstream of the first conveyance roller 118 and upstream of the second imaging device 121, and detects the medium conveyed to that position. The third medium sensor 120 includes a light emitter and a light receiver provided on one side with respect to the medium transport path, and a light guide tube provided at a position facing the light emitter and the light receiver across the medium transport path. including. The light emitter is an LED or the like, and emits light toward the medium transport path. On the other hand, the light receiver is a photodiode or the like, and receives the light emitted by the light emitter and guided by the light guide tube. The third medium sensor 120 generates a third medium signal whose signal value changes depending on whether the medium is present at the position of the third medium sensor 120 or not, based on the intensity of the light received by the light receiver. and output it.

Note that a reflective member such as a mirror may be used instead of the light guide tube. Further, the light emitter and the light receiver may be provided facing each other with the medium transport path in between. Further, the third medium sensor 120 may detect the presence of the medium using a contact detection sensor or the like that flows a predetermined current when the medium is in contact or not in contact with the medium.

The second imaging device 121 is disposed downstream of the first conveyance roller 118 and upstream of the second conveyance roller 122 in the medium conveyance direction A1, and is conveyed by the first conveyance roller 118 and the first driven roller 119. Image the medium. The second imaging device 121 includes a front imaging device 121a and a back imaging device 121b that are arranged to face each other across the medium transport path.

The surface imaging device 121a has a line sensor based on a CIS (Contact Image Sensor) of the same magnification optical system type and having imaging elements based on CMOS (Complementary Metal Oxide Semiconductor) arranged linearly in the main scanning direction. Further, the front surface imaging device 121a includes 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/digital (A/D) conversion. The surface imaging device 121a images the surface of the medium being conveyed, generates a medium image, and outputs the image, under control from a processing circuit described below.

Similarly, the back imaging device 121b has a CIS line sensor of the same magnification optical system type that has CMOS imaging elements arranged linearly in the main scanning direction. Further, the back imaging device 121b includes a lens that forms an image on the imaging device, and an A/D converter that amplifies the electrical signal output from the imaging device and performs analog/digital (A/D) conversion. The back side imaging device 121b images the back side of the medium being transported, generates a medium image, and outputs the image, under control from a processing circuit described later.

Note that the second imaging device 121 may have only one of the front imaging device 121a and the back imaging device 121b, and may read only one side of the medium. Further, instead of a line sensor using a CIS of a 1x optical system type including a CMOS image sensor, a line sensor using a CIS of a 1x optical system type including an image sensor using a CCD (Charge Coupled Device) may be used. Further, a reduction optical system type line sensor including a CMOS or CCD image sensor may be used.

The second conveyance roller 122 and the second driven roller 123 are arranged facing each other downstream from the second imaging device 121 in the medium conveyance direction A1, that is, from the first conveyance roller 118 and the first driven roller 119. . The second conveyance roller 122 is provided in the upper housing 102 and conveys the medium conveyed by the first conveyance roller 118 and the first driven roller 119 further downstream, and discharges the medium to the discharge table 104. Note that the second conveyance roller 122 may be provided in the lower casing 101 and the second driven roller 123 may be provided in the upper casing 102.

The medium placed on the mounting table 103 is transported between the lower guide 101a and the upper guide 102a in the medium transport direction A1 by the feeding roller 112 rotating in the medium transport direction A4. The medium feeding device 100 has two feeding modes: a separation mode in which the medium is fed while separating it, and a non-separation mode in which the medium is fed without separating it. The feeding mode is set by the user using the operating device 105 or an information processing device that is communicatively connected to the medium feeding device 100. When the feeding mode is set to the separation mode, the separation roller 113 rotates or stops in the direction A5 opposite to the medium feeding direction. Due to the action of the feeding roller 112 and separation roller 113, when a plurality of media are placed on the mounting table 103, only the medium that is in contact with the feeding roller 112 among the media placed on the mounting table 103 is removed. are separated. This restricts the conveyance of media other than the separated media (prevention of double feeding). On the other hand, when the feeding mode is set to non-separation mode, the separation roller 113 rotates in the medium feeding direction (the opposite direction of arrow A5).

The medium is fed between the first conveyance roller 118 and the first driven roller 119 while being guided by the lower guide 101a and the upper guide 102a. By rotating the first conveyance roller 118 and the first driven roller 119 in the forward directions A6 and A7, respectively, the image is sent between the front imaging device 121a and the back imaging device 121b. The medium read by the second imaging device 121 is discharged onto the discharge table 104 by the rotation of the second conveyance roller 122 and the second driven roller 123 in the directions of arrows A8 and A9, respectively.

FIG. 3 is a schematic diagram for explaining the light source device 114 and the first imaging device 115. FIG. 3 is a schematic diagram of the periphery of the medium transport path viewed from the upper housing 102 side.

In the example shown in FIG. 3, two feeding rollers 112, two separation rollers 113, two first conveyance rollers 118, two first driven rollers 119, two second conveyance rollers 122, and two second driven rollers 123 are arranged.

The light source device 114 includes a first light source device 114a and a second light source device 114b.

The first light source device 114a is an example of an irradiation unit. The first light source device 114a is installed in the upper housing 102 upstream of the nip N between the feeding roller 112 and separation roller 113 in the medium conveyance direction A1, and separated from the two sets of feeding rollers 112 in the width direction A2. It is arranged between each nip portion N of the roller 113. The first light source device 114a is an LED or the like, and emits light downward and downstream. The first light source device 114a illuminates a region that overlaps with the nip portion N when viewed from the width direction A2 perpendicular to the medium conveyance direction, that is, a region that overlaps with the nip portion N in the medium conveyance direction A1. The first light source device 114a illuminates the area between the two nip portions N in the width direction A2.

The second light source device 114b is an example of a second irradiation section. The second light source device 114b is installed in the upper housing 102 upstream of the nip N between the feeding roller 112 and separation roller 113 in the medium conveyance direction A1, and separated from the two sets of feeding rollers 112 in the width direction A2. It is arranged between each nip portion N of the roller 113. The second light source device 114b is an LED or the like, and emits light downward and downstream. The second light source device 114b irradiates an area that overlaps with the nip portion N when viewed from the width direction A2 orthogonal to the medium conveyance direction, that is, an area that overlaps with the nip portion N in the medium conveyance direction A1 from a direction different from that of the first light source device 114a. do. The second light source device 114b, like the first light source device 114a, illuminates the area between the two nip portions N in the width direction A2.

The second light source device 114b is arranged upstream of the first light source device 114a in the medium transport direction A1. That is, the angle between the light irradiation direction by the second light source device 114b and the medium transport path is smaller than the angle between the light irradiation direction by the first light source device 114a and the medium transport path. For example, the first light source device 114a is provided so that the angle between the light irradiation direction and the medium transport path is 45° or more and less than 90°, and the second light source device 114b is provided so that the light irradiation direction and the medium transport path are provided at an angle of 45° or more and less than 90°. The angle formed by the road is set to be less than 45° and greater than 0°.

The first imaging device 115 is an example of an imaging unit. The first imaging device 115 is installed in the upper housing 102 downstream of the nip N between the feeding roller 112 and the separation roller 113 in the medium conveyance direction A1, and separated from the two sets of feeding rollers 112 in the width direction A2. It is arranged between each nip portion N of the roller 113. The first imaging device 115 has a reduction optical system type imaging sensor that includes two-dimensionally arranged CCD imaging elements. The first imaging device 115 also includes a lens that forms an image on the imaging device, and an A/D converter that amplifies the electrical signal output from the imaging device and performs analog/digital (A/D) conversion. The first imaging device 115 overlaps the nip portion N when viewed from the width direction A2 orthogonal to the medium conveyance direction, and detects the leading edge position of the medium to be fed in a region between the two nips N in the width direction A2. An input image is generated by capturing the image.

Note that instead of a reduction optical system type image sensor including a CCD image sensor, a reduction optical system type image sensor including a CMOS image sensor may be used. Furthermore, a same-magnification optical system type image sensor including a CCD or CMOS image sensor may be used. Further, instead of an image sensor having image sensors arranged two-dimensionally, an image sensor (line sensor) having image sensors arranged one-dimensionally along the width direction A2 may be used. In that case, the first imaging device 115 generates a line image capturing a predetermined position of the medium to be fed at regular intervals, and generates an input image by combining the plurality of line images.

The input image generated by the first imaging device 115 is used to detect the state of the leading edge of the medium placed on the mounting table 103. By using a two-dimensional input image including the area between the two nips N, the medium feeding device 100 can detect the leading edge of the medium regardless of the position of the leading edge of the medium within the imaging range of the first imaging device 115. can appropriately detect the state of The medium feeding device 100 detects the state of the leading edge of the medium using one input image generated at a predetermined timing, compared to a case where the leading edge of the medium is continuously monitored at a predetermined position (point). The state of the leading edge of the medium can be detected with low load. Furthermore, since the medium feeding device 100 can detect the state of the leading edge of the medium using only one first imaging device 115 without using multiple sensors, increases in device cost and device size can be suppressed. can.

Furthermore, by capturing images from the downstream side toward the upstream side, the first imaging device 115 can generate an input image in which the leading edge of the medium is better captured. However, the medium to be fed is likely to be a white medium such as PPC (Plain Paper Copier) paper, and it may be difficult to identify its leading edge within the input image. On the other hand, by emitting light from the upstream side to the downstream side, the first light source device 114a can form a good shadow at the leading edge of the medium when viewed from the first imaging device 115 side. This allows the leading edge of the medium to be clearly included in the input image. Furthermore, the second light source device 114b can form a shadow having a thickness different from the shadow formed by the first light source device 114a on the leading edge of the medium by emitting light from a direction different from that of the first light source device 114a. I can do it. Therefore, the medium feeding device 100 detects the state of the leading edge of the medium with high accuracy by utilizing the difference in thickness of the shadow of the leading edge of the medium formed by the first light source device 114a and the second light source device 114b. be able to.

FIG. 4 is a schematic diagram for explaining the drive mechanism 130 of the separation roller 113. FIG. 4 is a schematic diagram of the vicinity of the separation roller 113 in the upper housing 102 viewed from above.

As shown in FIG. 4, the drive mechanism 130 includes a first motor 131, first to sixth gears 132a-f, first to fourth electromagnetic clutches 133a-d, first to fourth torque limiters 134a-d, etc. include.

The first motor 131 is connected to the separation roller 113 through the first to sixth gears 132a to 132f and the shaft 113a, and drives the separation roller 113. The first motor 131 generates a driving force for rotating the separation roller 113 in response to a control signal from the processing circuit, and causes the separation roller 113 to separate and feed the medium. The first motor 131 is, for example, a DC motor such as a brushed DC (Direct Current) motor. Note that the first motor 131 may be another DC motor such as a brushless DC motor, a stepping motor, or the like. The first motor 131 is provided so that the torque setting can be changed according to the supplied electric power.

The greater the amount of current supplied to the DC motor or stepping motor, that is, the greater the amount of electric power supplied to the DC motor or stepping motor, the greater the torque of the DC motor or stepping motor. Conversely, the smaller the amount of current supplied to the DC motor or stepping motor, that is, the smaller the amount of electric power supplied to the DC motor or stepping motor, the smaller the torque of the DC motor or stepping motor. Therefore, the medium feeding device 100 can change the torque of the first motor 131 by changing the amount of power supplied to the first motor 131. The medium feeding device 100 increases the amount of electric power supplied to the first motor 131 to increase the torque of the first motor 131 and reduce the torque applied to the separation roller 113 (the load applied to the medium by the separation roller 113). component) can be increased. On the other hand, the medium feeding device 100 reduces the amount of electric power supplied to the first motor 131 to reduce the torque of the first motor 131, thereby reducing the torque applied to the separation roller 113 (the torque applied to the medium by the separation roller 113). load component) can be reduced.

The first gear 132a is attached to the rotating shaft of the first motor 131. The first gear 132a is connected to the second gear 132b, the second gear 132b is connected to the third gear 132c, the third gear 132c is connected to the fourth gear 132d, the fourth gear 132d is connected to the fifth gear 132e, and the fifth gear 132e is connected to the fifth gear 132e. 6 gears 132f, respectively. The sixth gear 132f is attached to one end of the shaft 113a, which is the rotation axis of the separation roller 113.

The first electromagnetic clutch 133a is attached to the shaft that is the rotation axis of the second gear 132b, and the first torque limiter 134a is attached to the shaft that is the rotation axis of the second gear 132b via the first electromagnetic clutch 133a. The first torque limiter 134a defines the limit value of the torque applied to the separation roller 113 by defining the limit value of the torque applied to the second gear 132b. The limit value of the first torque limiter 134a is set such that when only the first torque limiter 134a is connected to the separation roller 113, the limit value of the torque applied to the separation roller 113 becomes the first limit value. That is, the limit value of the first torque limiter 134a is set such that the sum of the limit value of the first torque limiter 134a and the torque of the first motor 131 becomes the first limit value. The first electromagnetic clutch 133a is, for example, a micro powder clutch, and connects or disconnects power between the second gear 132b and the first torque limiter 134a according to a control signal from a processing circuit.

The second electromagnetic clutch 133b is attached to the shaft that is the rotation axis of the third gear 132c, and the second torque limiter 134b is attached to the shaft that is the rotation axis of the third gear 132c via the second electromagnetic clutch 133b. The second torque limiter 134b defines the limit value of the torque applied to the separation roller 113 by defining the limit value of the torque applied to the third gear 132c. The limit value of the second torque limiter 134b is set such that when only the second torque limiter 134b is connected to the separation roller 113, the limit value of the torque applied to the separation roller 113 becomes the second limit value. That is, the limit value of the second torque limiter 134b is set such that the sum of the limit value of the second torque limiter 134b and the torque of the first motor 131 becomes the second limit value. The second electromagnetic clutch 133b is, for example, a micro powder clutch, and connects or disconnects power between the third gear 132c and the second torque limiter 134b according to a control signal from a processing circuit.

The third electromagnetic clutch 133c is attached to the shaft that is the rotation axis of the fourth gear 132d, and the third torque limiter 134c is attached to the shaft that is the rotation axis of the fourth gear 132d via the third electromagnetic clutch 133c. The third torque limiter 134c defines the limit value of the torque applied to the separation roller 113 by defining the limit value of the torque applied to the fourth gear 132d. The limit value of the third torque limiter 134c is set such that when only the third torque limiter 134c is connected to the separation roller 113, the limit value of the torque applied to the separation roller 113 becomes the third limit value. That is, the limit value of the third torque limiter 134c is set such that the sum of the limit value of the third torque limiter 134c and the torque of the first motor 131 becomes the third limit value. The third electromagnetic clutch 133c is, for example, a micro powder clutch, and connects or disconnects power between the fourth gear 132d and the third torque limiter 134c according to a control signal from a processing circuit.

The fourth electromagnetic clutch 133d is attached to the shaft that is the rotation axis of the fifth gear 132e, and the fourth torque limiter 134d is attached to the shaft that is the rotation axis of the fifth gear 132e via the fourth electromagnetic clutch 133d. The fourth torque limiter 134d defines the limit value of the torque applied to the separation roller 113 by defining the limit value of the torque applied to the fifth gear 132e. The limit value of the fourth torque limiter 134d is set such that when only the fourth torque limiter 134d is connected to the separation roller 113, the limit value of the torque applied to the separation roller 113 becomes the fourth limit value. That is, the limit value of the fourth torque limiter 134d is set such that the sum of the limit value of the fourth torque limiter 134d and the torque of the first motor 131 becomes the fourth limit value. The fourth electromagnetic clutch 133d is, for example, a micro powder clutch, and connects or disconnects the power between the fifth gear 132e and the fourth torque limiter 134d according to a control signal from a processing circuit.

When the first to fourth electromagnetic clutches 133a to 133d respectively connect power, the torques applied to the second to fifth gears 132b to e are limited by the first to fourth torque limiters 134a to 134d, respectively. On the other hand, when the first to fourth electromagnetic clutches 133a to 133d are disconnecting power, the torques applied to the second to fifth gears 132b to e are not limited by the first to fourth torque limiters 134a to 134d, respectively.

The limit value of the torque applied to the separation roller 113 is an example of the torque value of the separation roller 113, and is an example of the characteristic value of the separation roller 113. The first limit value, the second limit value, the third limit value, and the fourth limit value are examples of the first torque value, the second torque value, the third torque value, and the fourth torque value, respectively.

The first limit value, the second limit value, the third limit value, and the fourth limit value are such that when there is only one medium to be fed, the transmission of the first driving force from the first motor 131 is cut off and the medium is fed. If there is a plurality of media, the value is set so that the first driving force from the first motor 131 is transmitted. As a result, when only one medium is fed, the separation roller 113 does not rotate according to the driving force from the first motor 131, but follows the feeding roller 112. That is, the separation roller 113 is set to rotate in the same direction as the feeding roller 112 when a torque equal to or greater than the limit value is applied. On the other hand, when a plurality of media are fed, the separation roller 113 rotates in the direction A5 opposite to the medium feeding direction, separates the medium in contact with the feeding roller 112 from other media, and prevent the occurrence of At this time, the outer circumferential surface of the separation roller 113 may apply a force in the direction A5 opposite to the medium feeding direction to the medium while being stopped without rotating in the direction A5 opposite to the medium feeding direction.

The limit value of the second torque limiter 134b is set to a larger value than the limit value of the first torque limiter 134a. The limit value of the third torque limiter 134c is set to a value greater than the limit value of the first torque limiter 134a and smaller than the limit value of the second torque limiter 134b. The limit value of the fourth torque limiter 134d is set to be the same as or larger than the limit value of the second torque limiter 134b. Furthermore, the limit values of the first to fourth torque limiters 134a to 134d are set to values smaller than the torque of the first motor 131. That is, the second limit value is set to a value larger than the first limit value. The third limit value is set to a value larger than the first limit value and smaller than the second limit value. The fourth limit value is set to the second limit value or a value larger than the second limit value. The medium feeding device 100 can change the limit value of the torque applied to the separation roller 113 by controlling the first to fourth electromagnetic clutches 133a to 133d.

Hereinafter, the first to fourth electromagnetic clutches 133a to 133d may be collectively referred to as the electromagnetic clutch 133. Note that the electromagnetic clutch 133 may be another type of clutch such as a hysteresis clutch. Further, instead of the electromagnetic clutch 133, an electromagnetic brake such as a micro powder brake or a hysteresis brake may be used.

FIG. 5 is a block diagram showing a schematic configuration of the medium feeding device 100.

In addition to the above-described configuration, the medium feeding device 100 further includes a second motor 141, a third motor 142, an interface device 143, a storage device 150, a processing circuit 160, and the like.

The second motor 141 rotates the feeding roller 112 to feed the medium in response to a control signal from the processing circuit 160.

The third motor 142 rotates the first conveyance roller 118 and the second conveyance roller in response to a control signal from the processing circuit 160 to convey the medium. Note that the first driven roller 119 and/or the second driven roller 123 may be provided so as to be driven by the driving force from the third motor 142.

The interface device 143 has an interface circuit similar to a serial bus such as a USB, and is electrically connected to an information processing device (for example, a personal computer, a mobile information terminal, etc.) (not shown) to transmit input images and various information. Send and receive. Further, instead of the interface device 143, a communication unit having an antenna for transmitting and receiving wireless signals and a wireless communication interface device for transmitting and receiving signals through a wireless communication line according to a predetermined communication protocol may be used. The predetermined communication protocol is, for example, a wireless LAN (Local Area Network). The communication unit may include a wired communication interface device for transmitting and receiving signals through a wired communication line according to a communication protocol such as a wired LAN.

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

The processing circuit 160 operates based on a program stored in the storage device 150 in advance. The processing circuit is, for example, a CPU (Central Processing Unit). As the processing circuit 160, a DSP (digital signal processor), an LSI (large scale integration), an ASIC (application specific integrated circuit), an FPGA (field-programmable gate array), or the like may be used.

The processing circuit 160 includes an operating device 105, a display device 106, a first medium sensor 111, a light source device 114, a first imaging device 115, a second medium sensor 117, a third medium sensor 120, a second imaging device 121, and a drive device 116c. , the first motor 131, the electromagnetic clutch 133, the second motor 141, the third motor 142, the interface device 143, the storage device 150, etc., and controls these parts. The processing circuit 160 performs drive control of each motor, imaging control of the second imaging device 121, etc. based on each medium signal received from each medium sensor. The processing circuit 160 acquires a medium image from the second imaging device 121 and transmits it to the information processing device via the interface device 143. Furthermore, the processing circuit 160 detects the leading edge position of the medium in the nip portion N based on the input image obtained from the first imaging device 115, and sets the characteristic value of the separation roller 113 based on the detection result.

FIG. 6 is a diagram showing a schematic configuration of the storage device 150 and the processing circuit 160.

As shown in FIG. 6, the storage device 150 stores a control program 151, a detection program 152, a setting program 153, and the like. Each of these programs is a functional module implemented by software running on a processor. The processing circuit 160 reads each program stored in the storage device 150 and operates according to each read program. Thereby, the processing circuit 160 functions as a control section 161, a detection section 162, and a setting section 163.

FIG. 7 is a flowchart showing an example of the operation of the medium reading process of the medium feeding device 100.

Hereinafter, an example of the operation of the medium reading process of the medium feeding device 100 will be described with reference to the flowchart shown in FIG. 7. Note that the operation flow described below is mainly executed by the processing circuit 160 in cooperation with each element of the medium feeding device 100 based on a program stored in the storage device 150 in advance.

First, a user inputs an instruction to read a medium using the operating device 105 or the information processing device, and the control unit 161 receives an operation signal instructing to read the medium from the operating device 105 or the interface device 143. (Step S101).

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

On the other hand, if a medium is placed on the mounting table 103, the processing circuit 160 executes a setting process (step S103). In the setting process, the processing circuit 160 detects the position of the leading edge of the medium in the nip portion N, and sets the characteristic value of the separation roller 113 based on the detection result. Details of the setting process will be described later.

Next, the control unit 161 rotates the feeding roller 112 to feed the medium by driving the second motor 141, and rotates the separation roller 113 by driving the first motor 131. Separate the media. Further, the control unit 161 rotates the first conveyance roller 118, the first driven roller 119, the second conveyance roller 122, and/or the second driven roller 123 by driving the third motor 142 to convey the medium. (Step S104). At this time, the separation roller 113 is rotating according to the characteristic value set in the setting process of step S103, and the medium feeding device 100 rotates the separation roller 113 according to the leading edge position of the medium placed on the mounting table 103. can be appropriately controlled and media can be appropriately separated.

Next, the control unit 161 waits until the leading edge of the fed medium passes through the nip between the first conveyance roller 118 and the first driven roller 119 (step S105). Hereinafter, the nip portion between the first conveyance roller 118 and the first driven roller 119 may be referred to as a conveyance section. The control unit 161 periodically acquires the third medium signal from the third medium sensor 120, and changes the signal value of the third medium signal from a value indicating that the medium is not present to a value indicating that the medium is present. When this happens, it is determined that the leading edge of the medium has passed the position of the third medium sensor 120. When the leading edge of the medium passes the position of the third medium sensor 120, the control unit 161 determines that the leading edge of the medium has passed the transport unit. Note that the control unit 161 may determine that the leading edge of the medium has passed the conveyance unit when a predetermined time has elapsed since the start of feeding the medium.

Next, the control unit 161 causes the second imaging device 121 to start imaging the medium (step S106).

Next, the control unit 161 controls the second motor 141 to stop the feeding roller 112 (step S107). Thereby, the medium is thereafter transported by the first transport roller 118 and the second transport roller 122, and the feeding roller 112 is rotated by the medium being transported. By stopping the feeding roller 112, the control unit 161 prevents the medium from being pushed by the feeding roller 112 and bending between the feeding roller 112 and the first conveying roller 118, resulting in a jam of the medium. can be suppressed.

Next, the control unit 161 determines whether there is any medium remaining on the mounting table 103 based on the first medium signal received from the first medium sensor 111 (step S108).

If the medium remains on the mounting table 103, the control unit 161 waits until the rear end of the fed medium passes through the nip N between the feeding roller 112 and separation roller 113 (step S109). In the following, the nip portion N between the feeding roller 112 and the separation roller 113 may be referred to as a separation portion. The control unit 161 periodically acquires a second medium signal from the second medium sensor 117, and changes the signal value of the second medium signal from a value indicating that a medium is present to a value indicating that a medium is not present. At this time, it is determined that the rear end of the medium has passed the position of the second medium sensor 117. When the rear end of the medium passes the position of the second medium sensor 117, the control unit 161 determines that the rear end of the medium has passed the separation unit. Note that the control unit 161 may determine that the rear end of the medium has passed the separation unit when a predetermined time has elapsed since the start of feeding the medium.

Next, the processing circuit 160 executes a setting process similar to the process in step S103 (step S110).

Next, the control unit 161 rotates the feeding roller 112 again by driving the second motor 141 to feed the following medium (step S111). That is, when the rear end of the preceding medium passes through the separating section, the control section 161 rotates the feeding roller 112 again and starts feeding the following medium. At this time, the separation roller 113 is rotating according to the characteristic value set in the setting process of step S110, and the medium feeding device 100 rotates the separation roller 113 according to the leading edge position of the medium placed on the mounting table 103. can be appropriately controlled and media can be appropriately separated.

Next, the control unit 161 waits until the rear end of the transported medium passes the imaging position of the second imaging device 121 (step S112). The control unit 161 periodically acquires a third medium signal from the third medium sensor 120, and changes the signal value of the third medium signal from a value indicating that a medium is present to a value indicating that a medium is not present. At this time, it is determined that the rear end of the medium has passed the position of the third medium sensor 120. The control unit 161 determines that the rear end of the medium has passed the imaging position when a first predetermined time has elapsed since the rear end of the medium passed the position of the third medium sensor 120 . The first predetermined time is set to the time required for the medium to move from the third medium sensor 120 to the imaging position. Note that the control unit 161 may determine that the rear end of the medium has passed the imaging position when a predetermined time has elapsed since the feeding of the medium was started.

Next, the control unit 161 acquires a medium image from the second imaging device 121, and outputs the acquired medium image by transmitting it to the information processing device via the interface device 143 (step S113).

Next, the control unit 161 returns the process to step S105, and repeats the process from step S105 on the subsequent medium.

On the other hand, in step S108, if there is no medium remaining on the mounting table 103, the control unit 161 causes the rear end of the transported medium to pass through the imaging position of the second imaging device 121 in the same manner as in step S112. The process waits until the process is completed (step S114).

Next, the control unit 161 acquires a medium image from the second imaging device 121, and outputs the acquired medium image by transmitting it to the information processing device via the interface device 143 (step S115).

Next, the control unit 161 waits until the rear end of the transported medium passes through the nip between the second transport roller 122 and the second driven roller 123 (step S116). Hereinafter, the nip portion between the second conveyance roller 122 and the second driven roller 123 may be referred to as a discharge portion. The control unit 161 determines that the rear end of the medium has passed the discharge unit when a second predetermined time period has elapsed since the rear end of the medium passed the position of the third medium sensor 120 . The second predetermined time is set to the time required for the medium to move from the position of the third medium sensor 120 to the downstream end of the discharge section. Note that the control unit 161 may determine that the trailing end of the medium has passed the discharge unit when a predetermined time has elapsed since the start of feeding the medium.

Next, the control unit 161 controls the second motor 141 and the third motor to stop the separation roller 113, the first conveyance roller 118, the first driven roller 119, the second conveyance roller 122, and/or the second driven roller 123. The motor 142 is controlled (step S117). With the above, the control unit 161 completes the series of steps.

FIG. 8 is a flowchart showing an example of the operation of the setting process.

The setting process is executed in steps S103 and S110 of the medium reading process in FIG.

First, the detection unit 162 obtains an input image from the first imaging device 115 (step S201). The detection unit 162 causes the first imaging device 115 to image the medium and generate an input image while causing the first light source device 114a to emit light and turning off the second light source device 114b. Note that the detection unit 162 may cause the first imaging device 115 to image the medium and generate the input image in a state where both the first light source device 114a and the second light source device 114b are irradiated with light.

FIGS. 9A and 9B and FIGS. 10A and 10B are schematic diagrams showing examples of input images P1, P2, P3, and P4, respectively.

For the input images P1 to P4, two sets of feeding rollers 112, separation rollers 113, and nip portions N are provided, respectively, so that the medium conveyance direction A1 coincides with the horizontal direction and the width direction A2 coincides with the vertical direction. The area in between is included. Furthermore, the input images P1 to P4 include media M1, M2, and M3 placed on the mounting table 103, respectively. The media M1, M2, and M3 are placed in this order from the bottom. In the input images P1 to P4, position C is the center position of the nip portion N in the medium conveyance direction A1, and positions F1 and F2 are the leading edge (downstream end) positions of the media M1 and M2, respectively.

As described above, the setting process is performed either before the start of medium feeding (step S103 in FIG. 7) or after the leading edge of the preceding medium passes through the conveyance section and stops the feeding roller 112. This is executed when the trailing end of the medium passes through the separating section (step S110 in FIG. 7). Before the start of medium feeding, when the user places multiple media on the mounting table 103, each medium is pushed into the separation part (nip part N), and the leading edge of each medium is stuck in the separation part (nip part N). ) may enter. In addition, after the start of medium feeding, when the rear end of the preceding medium passes through the separating section, the leading edge of the following medium may enter the separating section (nip N) being dragged by the preceding medium. There is sex.

In the input image P1, the leading edge position F1 of the medium M1 is located upstream of the center position C, and the inter-medium distance L between the leading edge position F1 of the medium M1 and the leading edge position F2 of the medium M2 is sufficient. big. In this case, the time during which the separating roller 113 applies the separating force to the media M1 and M2 is sufficiently long, and the separating force by the separating roller 113 is applied separately to the leading edge of the medium M1 and the leading edge of the medium M2. Therefore, there is a high possibility that the medium M1 and the medium M2 will be separated well.

In the input image P2, the leading edge position F1 of the medium M1 is located upstream of the center position C, and the inter-medium distance L between the leading edge position F1 of the medium M1 and the leading edge position F2 of the medium M2 is small. In this case, although the time during which the separating roller 113 applies the separating force to the media M1 and M2 is sufficiently long, the separating force by the separating roller 113 is applied integrally to the leading edge of the medium M1 and the leading edge of the medium M2. Therefore, compared to the state shown in the input image P1, the medium M1 and the medium M2 are difficult to separate.

In the input image P3, the leading edge position F1 of the medium M1 is located downstream of the center position C, and the inter-medium distance L between the leading edge position F1 of the medium M1 and the leading edge position F2 of the medium M2 is sufficient. big. In this case, the separating force by the separating roller 113 is applied separately to the leading edge of the medium M1 and the leading edge of the medium M2, but the time during which the separating force by the separating roller 113 is applied to the media M1 and M2 is short. Therefore, compared to the state shown in the input image P1, the medium M1 and the medium M2 are difficult to separate. However, in this case, the medium M1 and the medium M2 are more easily separated than in the state shown in the input image P2.

In the input image P4, the leading edge position F1 of the medium M1 is located downstream of the center position C, and the inter-medium distance L between the leading edge position F1 of the medium M1 and the leading edge position F2 of the medium M2 is small. In this case, the time during which the separating roller 113 applies the separating force to the media M1 and M2 is short, and the separating force by the separating roller 113 is applied integrally to the leading edge of the medium M1 and the leading edge of the medium M2. Therefore, compared to the states shown in the input images P1 to P3, the medium M1 and the medium M2 are less likely to be separated.

Next, the detection unit 162 detects the leading edge position of the medium at the nip portion N between the feeding roller 112 and the separation roller 113 (step S202). Based on the acquired input image, the detection unit 162 determines the leading edge position of the preceding medium (the medium to be fed next) and the medium next to the preceding medium (the medium to be fed second) in the nip portion N. Detect the position of the tip of the medium).

The medium feeding device 100 stores in advance in the storage device 150 the positions of the two sets of feeding rollers 112, separation rollers 113, and nip portions N in the input image, and predetermined positions in the medium conveyance direction A1 within each nip portion N. Remember it. The predetermined position is, for example, the center position C of the nip portion N in the medium conveyance direction A1. The predetermined position may be any other position within the nip portion N.

The detection unit 162 detects each pixel in the medium conveyance direction A1 (horizontal direction) in order from the downstream end (left end) at a specific position between the two nip portions N in the width direction A2 (vertical direction) in the input image. The difference is calculated by subtracting the gradation value of the pixel on the right from the gradation value of the pixel on the left. Below, this difference may be referred to as an adjacent difference value. The detection unit 162 detects pixels whose adjacent difference values exceed the gradation threshold as edge pixels. The gradation value is a brightness value, a color value (R value, G value, or B value), or the like. The gradation threshold is set, for example, to a difference in brightness value (for example, 20) that allows a person to visually distinguish a difference in brightness on an image. That is, the detection unit 162 starts from the lower end and detects pixels whose luminance value changes from a high value (color close to white) to a low value (color close to black) as edge pixels. The detection unit 162 detects the position of the first detected edge pixel, that is, the most downstream edge pixel, in the medium transport direction A1, as the leading edge position of the preceding medium. Furthermore, the detection unit 162 detects the position of the second detected edge pixel, that is, the second edge pixel located from the downstream side, in the medium conveyance direction A1, as the leading edge position of the medium following the preceding medium.

Note that the detection unit 162 may calculate the difference in gradation values of two pixels separated by a predetermined distance in the medium transport direction A1 from each pixel in the input image as an adjacent difference value. Further, the detection unit 162 may detect edge pixels by comparing the tone value of each pixel in the input image with a threshold value. For example, when the gradation value of a specific pixel is equal to or greater than the threshold value, and the gradation value of a pixel adjacent to the specific pixel on the upstream side or a pixel separated by a predetermined distance from the specific pixel is less than the threshold value, the detection unit 162 detects , detect that specific pixel as an edge pixel.

Next, the detecting unit 162 detects the inter-medium distance between the leading edge position of the preceding medium detected by the detecting unit 162 in the nip portion N and the leading edge position of the medium following the preceding medium (step S203). The detection unit 162 calculates the number of pixels detected in the input image between the leading edge position of the preceding medium and the leading edge position of the medium following the preceding medium. The medium feeding device 100 presets in the storage device 150 a table showing the relationship between the number of pixels in the image and the actual distance for each resolution of the input image. The detection unit 162 refers to a table preset in the storage device 150, and based on the resolution of the input image, determines the leading edge position of the preceding medium and the position of the next medium after the preceding medium, which corresponds to the calculated number of pixels. Determine the actual distance between the tip location and the tip location.

Next, the detection unit 162 determines whether the leading edge position of the preceding medium is located downstream in the medium conveyance direction A1 from a predetermined position within the nip portion N (step S204).

If the leading edge position of the preceding medium is not located downstream of the predetermined position, that is, if it is located upstream, the detection unit 162 detects the difference between the leading edge position of the preceding medium and the leading edge position of the medium following the preceding medium. It is determined whether the inter-medium distance between the media is equal to or greater than a threshold value (step S205). The threshold value is preset to the maximum value, average value, or the like of the distance between media when double feeding of media occurs in a preliminary experiment in which various types of media are fed.

When the inter-medium distance between the leading edge position of the preceding medium and the leading edge position of the medium following the preceding medium is equal to or greater than the threshold value, the setting unit 163 sets the limit value of the torque applied to the separation roller 113 to the first limit. value (step S206), and the series of steps ends. The setting unit 163 sets the first electromagnetic clutch 133a to connect the power between the second gear 132b and the first torque limiter 134a, and to disconnect the power between the other gear and the other torque limiter. Set other electromagnetic clutches. Thereby, the setting unit 163 sets the limit value of the torque applied to the separation roller 113 to the first limit value, and limits the load component applied to the medium by the separation roller 113 to the first limit value.

As shown in the input image P1, the setting unit 163 causes the separation roller 113 to This torque limit value is set as a first limit value. The setting unit 163 sets the limit value of the torque applied to the separation roller 113 to a sufficiently small first limit value when there is a high possibility that the medium M1 and the medium M2 will be separated well. Thereby, the medium feeding device 100 can suppress the occurrence of jamming of the medium due to an excessively large force with which the medium is sandwiched between the feeding roller 112 and the separation roller 113.

On the other hand, if the inter-medium distance between the leading edge position of the preceding medium and the leading edge position of the medium following the preceding medium is less than the threshold value, the setting unit 163 sets the limit value of the torque applied to the separation roller 113 to the maximum value. 2 limit value is set (step S207), and the series of steps ends. The setting unit 163 sets the second electromagnetic clutch 133b to connect the power between the third gear 132c and the second torque limiter 134b, and to disconnect the power between other gears and other torque limiters. Set other electromagnetic clutches. Thereby, the setting unit 163 sets the limit value of the torque applied to the separation roller 113 to the second limit value.

As shown in the input image P2, the setting unit 163 sets the separation roller 113 to This torque limit value is set as a second limit value. The setting unit 163 sets the limit value of the torque applied to the separation roller 113 to a second limit value that is larger than the first limit value when the medium M1 and the medium M2 are difficult to separate. Thereby, the medium feeding device 100 can increase the separation force exerted by the feeding roller 112 and the separation roller 113, thereby suppressing the occurrence of double feeding of the medium.

In step S204, if the leading edge position of the preceding medium is located downstream of the predetermined position, the detection unit 162 detects a difference between the leading edge position of the preceding medium and the leading edge position of the medium following the preceding medium. It is determined whether the inter-medium distance is equal to or greater than a threshold value (step S208).

If the inter-medium distance between the leading edge position of the preceding medium and the leading edge position of the medium following the preceding medium is equal to or greater than the threshold value, the setting unit 163 sets the limit value of the torque applied to the separation roller 113 to the third limit. value (step S209), and the series of steps ends. The setting unit 163 sets the third electromagnetic clutch 133c to connect the power between the fourth gear 132d and the third torque limiter 134c, and to disconnect the power between other gears and other torque limiters. Set other electromagnetic clutches. Thereby, the setting unit 163 sets the limit value of the torque applied to the separation roller 113 to the third limit value.

As shown in the input image P3, the setting unit 163 causes the separation roller 113 to This torque limit value is set as a third limit value. When the medium M1 and the medium M2 are slightly difficult to separate, the setting unit 163 sets the limit value of the torque applied to the separation roller 113 to a third limit value that is larger than the first torque value and smaller than the second torque value. As a result, the medium feeding device 100 slightly increases the separation force exerted by the feeding roller 112 and the separation roller 113, thereby suppressing the occurrence of a jam of the medium and the occurrence of double feeding of the medium. can.

If the inter-medium distance between the leading edge position of the preceding medium and the leading edge position of the medium following the preceding medium is less than the threshold value, the setting unit 163 sets the limit value of the torque applied to the separation roller 113 to the fourth limit. value (step S210), and the series of steps ends. The setting unit 163 sets the fourth electromagnetic clutch 133d to connect the power between the fifth gear 132e and the fourth torque limiter 134d, and to disconnect the power between other gears and other torque limiters. Set other electromagnetic clutches. Thereby, the setting unit 163 sets the limit value of the torque applied to the separation roller 113 to the fourth limit value.

As shown in the input image P4, the setting unit 163 sets the separation roller 113 to This torque limit value is set as a fourth limit value. The setting unit 163 sets the limit value of the torque applied to the separation roller 113 to a fourth limit value that is larger than the first limit value, the second limit value, and the third limit value when the medium M1 and the medium M2 are extremely difficult to separate. Set. Thereby, the medium feeding device 100 can extremely increase the separation force exerted by the feeding roller 112 and the separation roller 113, thereby suppressing the occurrence of double feeding of the medium.

In this way, the setting unit 163 sets the setting unit 163 according to the inter-medium distance between the leading edge position of the preceding medium detected by the detecting unit 162 in the nip portion N and the leading edge position of the medium following the preceding medium. The limit value of the torque applied to the separation roller 113 is changed. Further, the setting unit 163 sets a limit on the torque applied to the separation roller 113 depending on whether the leading edge position F1 of the preceding medium detected by the detection unit 162 is located downstream of the predetermined position in the medium conveyance direction A1. Change the value. Thereby, the medium feeding device 100 can suppress the occurrence of double feeding of media while suppressing the occurrence of a jam of the medium.

Further, the setting process is executed immediately before the feeding roller 112 starts rotating (steps S105 and S111 in FIG. 7). That is, the detection unit 162 detects the leading edge position of the medium immediately before the feeding roller 112 starts rotating, and the setting unit 163 sets the characteristics of the separation roller 113 according to the detection result. Thereby, the medium feeding device 100 can appropriately change the characteristics of the separation roller 113 according to the state of the medium on the mounting table 103 immediately before the start of feeding, and can separate the medium well. .

Note that the processes in steps S204 and S208 to S210 are omitted, and the setting unit 163 changes the limit value of the torque applied to the separation roller 113 only according to the inter-medium distance, regardless of the leading edge position F1 of the preceding medium. It's okay. Further, the processes of steps S205, S207, S208, and S210 are omitted, and the setting unit 163 sets the limit value of the torque applied to the separation roller 113 only according to the leading edge position F1 of the preceding medium, regardless of the distance between the media. May be changed.

Furthermore, the detection unit 162 may detect the leading edge position of each medium in the nip portion N using information other than the input image. In that case, the medium feeding device 100 includes a plurality of overlap sensors for detecting overlapping of media instead of the light source device 114 and the first imaging device 115. The plurality of overlap sensors are arranged between each nip portion N of the two sets of feeding rollers 112 and separation rollers 113 in the width direction A2. Further, the plurality of overlap sensors are arranged side by side at intervals at positions overlapping with the nip portion N when viewed from the width direction A2, that is, at positions overlapping with the nip portion N in the medium conveyance direction A1.

The overlap sensor is, for example, an ultrasonic sensor. Each ultrasonic sensor includes an ultrasonic transmitter and an ultrasonic receiver. Each ultrasonic transmitter and each ultrasonic receiver are arranged in the vicinity of the medium transport path, facing each other across the transport path. The ultrasonic transmitter emits ultrasonic waves. On the other hand, an ultrasonic receiver receives ultrasonic waves transmitted by an ultrasonic transmitter and passed through a medium, and generates and outputs an ultrasonic signal that is an electric signal corresponding to the received ultrasonic waves. At a position where a medium is present, the ultrasonic waves emitted by the ultrasonic sensor are attenuated by the medium, so that the signal value of the ultrasonic signal decreases. Further, at a position where the media overlap, the ultrasonic waves emitted by the ultrasonic sensor are attenuated by the air layer between the plurality of media, so that the signal value of the ultrasonic signal further decreases.

In this case, in step S201, the detection unit 162 acquires ultrasonic signals from each ultrasonic sensor. In step S202, the detection unit 162 determines whether the signal value of the ultrasonic signal outputted by each ultrasonic sensor is below a first ultrasonic threshold and whether it is below a second ultrasonic threshold which is smaller than the first ultrasonic threshold. Determine whether or not. The first ultrasonic threshold is, for example, a value between the signal value of the ultrasonic signal detected when no medium is present and the signal value of the ultrasonic signal detected when a single sheet of PPC paper is present. Set. The second ultrasonic threshold is a value between the signal value of the ultrasonic signal detected when one sheet of PPC paper is present and the transmission information detected when two sheets of PPC paper are conveyed. Set.

The detection unit 162 detects the position of the most downstream ultrasonic sensor among the ultrasonic sensors whose output ultrasonic signal value is equal to or less than the first ultrasonic threshold value, as the leading edge position of the preceding medium. . In addition, the detection unit 162 detects the position of the ultrasonic sensor that is located on the most downstream side among the ultrasonic sensors whose signal value of the output ultrasonic signal is equal to or lower than the second ultrasonic threshold, and determines the position of the ultrasonic sensor that is located on the next medium of the preceding medium. Detected as the tip position of

The overlap sensor may be a thickness sensor. Each thickness sensor includes a light emitter and a light receiver. Each light emitter and each light receiver are arranged in the vicinity of the medium transport path, facing each other across the transport path. The light emitter emits light (infrared light or visible light) toward the light receiver. On the other hand, the light receiver receives the light emitted by the light emitter, generates and outputs a thickness signal that is an electrical signal according to the intensity of the received light. If a medium is present at the location of the thickness sensor, the light emitted by the light emitter will be attenuated by the medium, and the greater the thickness of the medium, the greater the amount of attenuation. For example, a thickness sensor generates a thickness signal such that the greater the thickness of the medium, the greater the signal value.

Note that a reflected light sensor, a pressure sensor, or a mechanical sensor may be used as the thickness sensor. The reflected light sensor includes a pair of a light emitter and a light receiver provided on one side with respect to a medium transport path, and a pair of a light emitter and a light receiver provided on the other side. Reflected light sensors measure the time from when one pair irradiates light to one side of the medium until the reflected light is received, and the time from when the other pair irradiates light to the other side of the medium until the reflected light is received. The distance between each pair and each surface of the medium is detected based on the time until light is received. The reflected light sensor generates a thickness signal that represents the distance between the two pairs minus each detected distance. A pressure sensor detects a pressure that varies depending on the thickness of the medium and generates a thickness signal indicative of the detected pressure. The mechanical sensor detects the amount of movement of the roller in contact with the media and generates a thickness signal indicative of the detected amount of movement.

In this case, in step S201, the detection unit 162 acquires a thickness signal from each thickness sensor. In step S202, the detection unit 162 determines whether the signal value of the thickness signal output by each thickness sensor is greater than or equal to the first thickness threshold, and whether it is less than or equal to a second thickness threshold that is greater than the first thickness threshold. Determine whether or not. The first thickness threshold value is, for example, a value between the signal value of the thickness signal detected when no medium is present and the signal value of the thickness signal detected when one sheet of PPC paper is present. Set. The second thickness threshold is a value between the signal value of the ultrasonic signal detected when one sheet of PPC paper is present and the transmission information detected when two sheets of PPC paper are conveyed. Set.

The detection unit 162 detects, as the leading edge position of the preceding medium, the position of the thickness sensor located on the most downstream side among the thickness sensors whose signal value of the output thickness signal is equal to or greater than the first thickness threshold value. . In addition, the detection unit 162 detects the position of the thickness sensor that is located on the most downstream side among the thickness sensors whose signal value of the output thickness signal is equal to or less than the second thickness threshold value, and determines the position of the thickness sensor that is located on the next medium of the preceding medium. Detected as the tip position of

Furthermore, in steps S206, S207, S209, and S210, the setting unit 163 may change the torque applied to the separation roller 113 by changing the torque of the first motor 131 instead of changing the torque limiter. good.

In that case, in steps S206, S207, S209, and S210, the setting unit 163 changes the torque of the first motor 131 instead of changing the first to fourth electromagnetic clutches 133a to 133d. The torque limit value applied to 113 is changed. In step S206, the setting unit 163 sets the limit value of the torque applied to the separation roller 113 to be the first torque value, that is, the limit value of the torque limiter connected to the separation roller 113 and the torque of the first motor 131. The torque of the first motor 131 is set so that the total becomes the first limit value. In step S207, the setting unit 163 sets the limit value of the torque applied to the separation roller 113 to be the second torque value, that is, the limit value of the torque limiter connected to the separation roller 113 and the torque of the first motor 131. The torque of the first motor 131 is set so that the total becomes the second limit value. In step S209, the setting unit 163 sets the limit value of the torque applied to the separation roller 113 to be the third torque value, that is, the limit value of the torque limiter connected to the separation roller 113 and the torque of the first motor 131. The torque of the first motor 131 is set so that the total becomes the third limit value. In step S210, the setting unit 163 sets the limit value of the torque applied to the separation roller 113 to be the fourth torque value, that is, the limit value of the torque limiter connected to the separation roller 113 and the torque of the first motor 131. The torque of the first motor 131 is set so that the total becomes the fourth limit value.

The setting unit 163 changes the torque of the first motor 131 by setting the amount of power (current) supplied to the first motor 131 to the amount of power (current) corresponding to each torque.

As described in detail above, the medium feeding device 100 separates the medium according to the distance between the leading edge position of the preceding medium and the leading edge position of the next medium at the nip portion N between the feeding roller 112 and the separation roller 113. The torque value, which is a characteristic value of the roller 113, is changed. Thereby, the medium feeding device 100 can appropriately change the separation force of the separation roller 113 according to the feeding state (separation state) of the medium placed on the mounting table 103, and prevent media from jamming. It is possible to suppress the occurrence of double feeding of media while suppressing the occurrence of this. Therefore, the medium feeding apparatus 100 can appropriately suppress the occurrence of double feeding of the medium.

FIG. 11 is a flowchart showing another example of the operation of the setting process.

The flowchart shown in FIG. 11 is executed instead of the flowchart shown in FIG. The processing in steps S301 to S305 and S308 in FIG. 11 is the same as the processing in steps S201 to S205 and S208 in FIG. 8, so the explanation will be omitted, and only steps S306 to S307 and S309 to S310 will be explained below.

In step S306, the setting unit 163 sets the pressing force for pressing the separation roller 113 toward the feeding roller 112 side by the pressing mechanism 116 as the first pressing force (step S306), and ends the series of steps. The first pressing force is set to a sufficiently large value. The setting unit 163 controls the drive device 116c of the pressing mechanism 116 so that the pressing force by the pressing mechanism 116 becomes the first pressing force. The pressing force with which the pressing mechanism 116 presses the separation roller 113 toward the feeding roller 112 is an example of a characteristic value of the separation roller 113.

In this way, the setting unit 163 is configured such that the leading edge position of the preceding medium is located upstream of a predetermined position within the nip portion N, and the setting unit 163 is configured to set the position of the leading edge of the medium between the leading edge position of the preceding medium and the leading edge position of the next medium. If the distance is equal to or greater than the threshold, the pressing force by the pressing mechanism 116 is set to the first pressing force. The setting unit 163 sets the pressing force for pressing the separation roller 113 toward the feeding roller 112 to a sufficiently large first pressing force when there is a high possibility that the plurality of media will be separated satisfactorily. As a result, the medium feeding device 100 can firmly sandwich the medium between the feeding roller 112 and the separation roller 113, thereby suppressing the occurrence of a jam of the medium.

In step S307, the setting unit 163 sets the pressing force for pressing the separating roller 113 toward the feeding roller 112 side by the pressing mechanism 116 as the second pressing force (step S307), and ends the series of steps. The second pressing force is set to a smaller value than the first pressing force. The setting unit 163 controls the drive device 116c of the pressing mechanism 116 so that the pressing force by the pressing mechanism 116 becomes the second pressing force.

In this way, the setting unit 163 is configured such that the leading edge position of the preceding medium is located upstream of a predetermined position within the nip portion N, and the setting unit 163 is configured to set the position of the leading edge of the medium between the leading edge position of the preceding medium and the leading edge position of the next medium. If the distance is less than the threshold, the pressing force by the pressing mechanism 116 is set to the second pressing force. The setting unit 163 sets the pressing force for pressing the separation roller 113 toward the feeding roller 112 to a second pressing force that is smaller than the first pressing force when the plurality of media are difficult to separate. Thereby, the medium feeding device 100 can easily return the medium to the mounting table 103 side by the separation roller 113, and can suppress the occurrence of double feeding of the medium.

In step S309, the setting unit 163 sets the pressing force for pressing the separation roller 113 toward the feeding roller 112 side by the pressing mechanism 116 as the third pressing force (step S309), and ends the series of steps. The third pressing force is set to a value smaller than the first pressing force and larger than the second pressing force. The setting unit 163 controls the drive device 116c of the pressing mechanism 116 so that the pressing force by the pressing mechanism 116 becomes the third pressing force.

In this way, the setting unit 163 is configured such that the leading edge position of the preceding medium is located downstream of a predetermined position within the nip portion N, and the setting unit 163 is configured to set the position of the leading edge of the medium between the leading edge position of the preceding medium and the leading edge position of the next medium. If the distance is equal to or greater than the threshold, the pressing force by the pressing mechanism 116 is set to the third pressing force. The setting unit 163 sets the pressing force for pressing the separating roller 113 toward the feeding roller 112 side to a third pressing force that is smaller than the first pressing force and larger than the second pressing force when the plurality of media are slightly difficult to separate. do. Thereby, the medium feeding device 100 can make it easier to return the medium to the mounting table 103 side by the separation roller 113, thereby suppressing the occurrence of a jam of the medium and the occurrence of double feeding of the medium.

In step S310, the setting unit 163 sets the pressing force for pressing the separation roller 113 toward the feeding roller 112 side by the pressing mechanism 116 as the fourth pressing force (step S310), and ends the series of steps. The fourth pressing force is set to a smaller value than the second pressing force. The setting unit 163 controls the drive device 116c of the pressing mechanism 116 so that the pressing force by the pressing mechanism 116 becomes the fourth pressing force.

In this way, the setting unit 163 is configured such that the leading edge position of the preceding medium is located downstream of a predetermined position within the nip portion N, and the setting unit 163 is configured to set the leading edge position of the preceding medium to be located downstream of the predetermined position within the nip portion If the distance is less than the threshold, the pressing force by the pressing mechanism 116 is set to the fourth pressing force. When the plurality of media are extremely difficult to separate, the setting unit 163 sets the pressing force for pressing the separating roller 113 toward the feeding roller 112 to a fourth pressing force that is smaller than the first pressing force, the second pressing force, and the third pressing force. Set to pressing force. Thereby, the medium feeding device 100 can make it extremely easy to return the medium to the mounting table 103 side by the separation roller 113, and can suppress the occurrence of double feeding of the medium.

Note that, similar to the setting process in FIG. 8, steps S304 and S308 to S310, or steps S305, S307, S308, and S310 may be omitted. Further, the detection unit 162 may detect the leading edge position of each medium in the nip portion N using an overlap sensor.

As described in detail above, the medium feeding device 100 changes the pressing force for pressing the separation roller 113 toward the feeding roller 112 side using the pressing mechanism 116 depending on the distance between the preceding medium and the next medium. In this case, it is now possible to appropriately suppress the occurrence of double feeding of media.

FIG. 12 is a flowchart showing still another example of the operation of the setting process.

The flowchart shown in FIG. 12 is executed instead of the flowchart shown in FIG. The processes in steps S401, S408-S409, and S411-S412 in FIG. 12 are the same as the processes in steps S201, S206-S207, and S209-S210 in FIG. I will only explain about.

In step S402, the detection unit 162 turns off the first light source device 114a and causes the second light source device 114b to emit light (step S402).

Next, the detection unit 162 acquires a second input image from the first imaging device 115 (step S403). That is, the detection unit 162 causes the first imaging device 115 to image the medium and generate an input image while the first light source device 114a is turned off and the second light source device 114b is irradiated with light.

FIGS. 13A and 13B are schematic diagrams showing examples of second input images P5 and P6, respectively.

Similar to input images P1 to P4, second input images P5 and P6 include two sets of feeding rollers 112, separation rollers 113, and nip portion N, an area between them, and images placed on mounting table 103, respectively. media M1, M2, and M3 are included. In the second input image P5, the leading edge position F1 of the medium M1 is located upstream of the center position C, and the inter-medium distance between the leading edge position F1 of the medium M1 and the leading edge position F2 of the medium M2 is sufficient. big. On the other hand, in the second input image P6, the leading edge position F1 of the medium M1 is located upstream of the center position C, and the inter-medium distance between the leading edge position F1 of the medium M1 and the leading edge position F2 of the medium M2 is is small.

As described above, the angle between the light irradiation direction by the second light source device 114b and the medium transport path is smaller than the angle between the light irradiation direction by the first light source device 114a and the medium transport path. Therefore, the length T of the shadow of the tip of each medium M1, M2 in the medium transport direction A1 in the second input image captured with only the second light source device 114b irradiating light is the length T of each medium M1 in the input image. , M2 is longer than the length of the shadow of the tip in the medium transport direction A1. Therefore, as shown in the second input image P6, when the inter-medium distance between the leading edge position F1 of the medium M1 and the leading edge position F2 of the medium M2 is small, the shadow of the leading edge of the medium M1 and the shadow of the leading edge of the medium M2 are are connected.

Next, the detection unit 162 detects the leading edge position of the medium at the nip portion N between the feeding roller 112 and the separation roller 113 (step S404). The detection unit 162 detects the leading edge position of the preceding medium and the leading edge position of the medium following the preceding medium at the nip portion N from the input image and the second input image, respectively, in a manner similar to the process of step S202 in FIG. and detect.

Next, the detecting unit 162 detects the inter-medium distance between the leading edge position of the preceding medium detected by the detecting unit 162 in the nip portion N and the leading edge position of the medium following the preceding medium (step S405). The detection unit 162 identifies the inter-medium distance between the leading edge position of the preceding medium and the leading edge position of the medium following the preceding medium, based on the input image, in a similar manner to the process of step S202 in FIG. do. Furthermore, the detection unit 162 identifies the inter-medium distance between the leading edge position of the preceding medium and the leading edge position of the medium following the preceding medium, based on the second input image.

The detection unit 162 detects edge pixels from the second input image in the same manner as the process in step S202 of FIG. In addition, the detection unit 162 detects each pixel in the medium transport direction A1 in order from the downstream end (left end) at a specific position between the two nip portions N in the width direction A2 (vertical direction) in the second input image. A difference is calculated by subtracting the gradation value of the pixel on the left from the gradation value of the pixel on the right (in the horizontal direction). Hereinafter, this difference may be referred to as a second adjacent difference value. The detection unit 162 detects a pixel whose adjacent difference value exceeds the gradation threshold as a second edge pixel. That is, the detection unit 162 detects pixels whose brightness value changes from a low value (color close to black) to a high value (color close to white) as second edge pixels, starting from the lower end side. The detection unit 162 calculates the number of pixels between the first detected edge pixel and the second edge pixel.

The detection unit 162 refers to a table preset in the storage device 150 that shows the relationship between the number of pixels in the image and the actual distance, and calculates the distance corresponding to the calculated number of pixels by the length of the shadow of the preceding medium. Specify as. If the identified length of the shadow of the preceding medium is less than the threshold, the detection unit 162 detects that the shadow of the preceding medium is not connected to the shadow of the next medium, and the leading edge position of the preceding medium and the next medium are not connected. It is determined that the distance between the media and the tip position of the media is equal to or greater than the threshold value. On the other hand, if the identified length of the shadow of the preceding medium is equal to or greater than the threshold, the detection unit 162 determines that the shadow of the preceding medium and the shadow of the next medium are connected, and that the leading edge position of the preceding medium and the next medium are connected. It is determined that the distance between the media and the leading edge position of the media is less than a threshold value.

Note that the thicker the medium being fed, the longer the shadow of the leading edge of the medium becomes in the input image. Therefore, the detection unit 162 may change the threshold value depending on the thickness of the medium being fed. Since it is highly likely that the types (thicknesses) of the media placed on the mounting table 103 are the same, for example, the detection unit 162 detects the length of the shadow of the leading edge of the medium fed after the preceding medium. Estimate the thickness of the media. The detection unit 162 detects the area between the second (or third or later) detected edge pixel and the second edge pixel as the shadow of the leading edge of the medium fed after the preceding medium. The detection unit 162 sets a distance corresponding to the number of pixels in the area as a threshold value for comparison with the length of the shadow of the preceding medium. As a result, the detection unit 162 can detect the inter-medium distance between the leading edge position of the preceding medium and the leading edge position of the next medium after the preceding medium with high precision, regardless of the thickness of the medium being fed. can do.

Next, the detection unit 162 determines whether the leading edge position of the preceding medium is located downstream in the medium transport direction A1 from a predetermined position within the nip portion N (step S406).

When both the leading edge position of the preceding medium detected from the input image and the leading edge position of the preceding medium detected from the second input image are located downstream of a predetermined position, the detecting unit 162 detects that the leading edge position of the preceding medium is It is determined that the position is downstream from the predetermined position. On the other hand, if at least one of the leading edge position of the preceding medium detected from the input image and the leading edge position of the preceding medium detected from the second input image is located upstream of the predetermined position, the detecting unit 162 detects the leading edge of the preceding medium. It is determined that the tip position is located upstream of the predetermined position. Note that when at least one of the leading edge position of the preceding medium detected from the input image and the leading edge position of the preceding medium detected from the second input image is located downstream of a predetermined position, the detecting unit 162 detects the position of the leading edge of the preceding medium. It may be determined that the tip position is located downstream of the predetermined position. In that case, if both the leading edge position of the preceding medium detected from the input image and the leading edge position of the preceding medium detected from the second input image are located upstream of the predetermined position, the detecting unit 162 detects the leading edge of the preceding medium. It is determined that the tip position is located upstream of the predetermined position.

Furthermore, in steps S407 and S410, the detection unit 162 determines whether the inter-medium distance between the leading edge position of the preceding medium and the leading edge position of the medium following the preceding medium is equal to or greater than a threshold ( Steps S407, S410).

When both the inter-medium distance detected from the input image and the inter-medium distance detected from the second input image are equal to or greater than the threshold, the detection unit 162 detects the leading edge position of the preceding medium and the leading edge of the medium following the preceding medium. It is determined that the distance between the media and the position is equal to or greater than a threshold value. On the other hand, when at least one of the inter-medium distance detected from the input image and the inter-medium distance detected from the second input image is less than the threshold, the detection unit 162 detects the leading edge position of the preceding medium and the next medium distance of the preceding medium. It is determined that the distance between the media and the leading edge position of the media is less than a threshold value. Note that when at least one of the inter-medium distance detected from the input image and the inter-medium distance detected from the second input image is equal to or greater than the threshold, the detection unit 162 detects the leading edge position of the preceding medium and the next medium of the preceding medium. It may be determined that the distance between the medium and the leading edge position of the medium is equal to or greater than a threshold value. In that case, if both the inter-medium distance detected from the input image and the inter-medium distance detected from the second input image are less than the threshold, the detection unit 162 detects the leading edge position of the preceding medium and the next medium distance of the preceding medium. It is determined that the distance between the media and the leading edge position of the media is less than a threshold value.

In this way, the detection unit 162 uses two input images taken with different light irradiation directions to detect the leading edge position of the medium, and the difference between the leading edge position of the preceding medium and the leading edge position of the next medium. Detect the distance between media. Thereby, the detection unit 162 can detect the leading edge position of the medium and the distance between the media with higher accuracy. Note that the detection unit 162 may detect the leading edge position of the medium and the distance between the media using only the second input image without using the input image.

Note that, similar to the setting process in FIG. 8, steps S406 and S410 to S412, or steps S407, S409, S410, and S412 may be omitted. Further, in steps S408 to S409 and S411 to S412, the setting unit 163 may set the pressing force by the pressing mechanism 116 in the same manner as in steps S306 to S307 and S309 to S310 in FIG. 11, respectively.

As described in detail above, the medium feeding device 100 uses two input images generated with different light irradiation directions to detect the leading edge position of the medium and the distance between the media. This makes it possible to appropriately suppress the occurrence of transport.

FIG. 14 is a diagram showing a schematic configuration of a processing circuit 260 in a medium feeding device according to yet another embodiment. The processing circuit 260 is used in place of the processing circuit 160 and executes media reading processing, etc. in place of the processing circuit 160. The processing circuit 260 includes a control circuit 261, a detection circuit 262, a setting circuit 263, and the like. Note that each of these units may be configured with an independent integrated circuit, microprocessor, firmware, or the like.

The control circuit 261 is an example of a control section and has the same functions as the control section 161. The control circuit 261 receives an operation signal from the operation device 105 or the interface device 143. The control circuit 261 also receives a first medium signal, a second medium signal, and a third medium signal from the first medium sensor 111, the second medium sensor 117, and the third medium sensor 120, respectively. The control circuit 261 controls the first motor 131 , the second motor 141 , and the third motor 142 based on the received signals, acquires a medium image from the second imaging device 121 , and outputs it to the interface device 143 .

The detection circuit 262 is an example of a detection section and has the same function as the detection section 162. The detection circuit 262 receives an input image from the first imaging device 115 while controlling the light source device 114 . The detection circuit 262 detects the leading edge position of the medium and the distance between the media based on the received input image, and outputs the detection result to the setting circuit 263.

The setting circuit 263 is an example of a setting section and has the same function as the setting section 163. The setting circuit 263 receives the detection results of the leading edge position of the medium and the distance between the media from the detection circuit 262, and controls the electromagnetic clutch 133, the first motor 131, or the drive device 116c based on the received detection results.

As described in detail above, even when using the processing circuit 260, the medium feeding device can appropriately suppress the occurrence of double feeding of media.

Although preferred embodiments have been described above, the embodiments are not limited to these. For example, in the medium feeding device, instead of the first to fourth electromagnetic clutches 133a to 133d and the first to fourth torque limiters 134a to 134d, one electromagnetic clutch for defining the limit value of the torque applied to the separation roller 113 is used. A clutch may also be used. The setting unit 163 controls the electromagnetic clutch to change the limit value of the torque applied to the separation roller 113 instead of switching the first to fourth torque limiters 134a to 134d. Also in this case, the medium feeding device can appropriately suppress the occurrence of double feeding of the medium.

Further, the medium feeding device may have a so-called U-turn path, and may feed and convey the medium placed on the mounting table sequentially from the top and discharge it onto the discharge table. In that case, the separating roller is arranged below the feeding roller and facing the feeding roller. The first light source device and the second light source device are arranged below the medium transport path and emit light upward (the medium transport path). The first imaging device is disposed below the medium transport path and images the upper side. Also in this case, the medium feeding device can appropriately suppress the occurrence of double feeding of the medium.

100 Media feeding device, 112 Feeding roller, 113 Separation roller, 116 Pressing mechanism, 114a First light source device, 114b Second light source device, 115 First imaging device, 162 Detection unit, 163 Setting unit

Claims

A mounting table and
a feeding roller that sequentially feeds the plurality of media placed on the mounting table;
a separation roller disposed opposite to the feeding roller;
a detection unit that detects a leading edge position of the medium at a nip portion between the feeding roller and the separation roller;
a setting section for setting characteristic values of the separation roller;
The setting section sets the characteristic value according to an inter-medium distance between a leading edge position of a preceding medium detected by the detecting section in the nip section and a leading edge position of a medium next to the preceding medium. change,
A medium feeding device characterized by:
The characteristic value is a torque value,
The separating roller is set to rotate in the same direction as the feeding roller when a torque equal to or greater than the torque value is applied,
The setting unit sets the torque value to a first torque value when the inter-medium distance is equal to or greater than a threshold value, and sets the torque value to a first torque value when the inter-medium distance is less than the threshold value. The medium feeding device according to claim 1, wherein the medium feeding device is set to a large second torque value.
The setting unit is configured to adjust the torque when the leading edge position of the preceding medium detected by the detection unit is located downstream in the medium conveyance direction from a predetermined position in the nip and the inter-medium distance is equal to or greater than the threshold value. The medium feeding device according to claim 2, wherein the torque value is set to a third torque value that is larger than the first torque value and smaller than the second torque value.
The setting unit is configured to adjust the torque when the leading edge position of the preceding medium detected by the detection unit is located downstream in the medium conveyance direction from a predetermined position in the nip and the inter-medium distance is less than the threshold value. The medium feeding device according to claim 2 or 3, wherein the value is set to the second torque value or a fourth torque value larger than the second torque value.
further comprising a pressing part that presses the separation roller toward the feeding roller,
The characteristic value is a pressing force for pressing the separating roller toward the feeding roller by the pressing portion,
The setting unit sets the pressing force to a first pressing force when the inter-medium distance is equal to or greater than a threshold value, and sets the pressing force to a first pressing force when the inter-medium distance is less than the threshold value. The medium feeding device according to claim 1 or 2, wherein the second pressing force is set to be small.
The medium feeding device according to claim 1 or 2, wherein the detection unit detects the tip position immediately before starting rotation of the feeding roller.
further comprising an imaging unit that generates an input image capturing a leading edge position of the medium in a region overlapping the nip portion when viewed from a direction perpendicular to the medium conveyance direction;
The medium feeding device according to claim 1 or 2, wherein the detection section detects a leading edge position of the medium in the nip section based on the input image.
The medium feeding device according to claim 7, wherein the imaging section is arranged downstream of the nip section in the medium conveyance direction.
The medium feeding device according to claim 8, further comprising an irradiation unit disposed upstream of the nip portion in the medium transport direction and irradiating an area overlapping with the nip portion when viewed from a direction perpendicular to the medium transport direction.
The method further comprises a second irradiation section that is disposed upstream of the nip section in the medium transport direction and irradiates a region that overlaps the nip section when viewed from a direction perpendicular to the medium transport direction from a direction different from that of the irradiation section. Item 9. The medium feeding device according to item 9.
A feeding roller sequentially feeds multiple media placed on the mounting table,
detecting a leading edge position of the medium at a nip portion between a feeding roller and a separation roller disposed opposite to the feeding roller;
setting a characteristic value of the separation roller;
In the setting, the characteristic value is changed according to an inter-medium distance between a leading edge position of a preceding medium detected in the nip portion and a leading edge position of a medium next to the preceding medium.
A medium feeding method characterized by:
A control program for a medium feeding device including a mounting table, a feeding roller that sequentially feeds a plurality of media placed on the mounting table, and a separation roller disposed opposite to the feeding roller. There it is,
detecting the leading edge position of the medium at the nip between the feeding roller and the separating roller;
causing the medium feeding device to set a characteristic value of the separation roller;
In the setting, the characteristic value is changed according to an inter-medium distance between a leading edge position of a preceding medium detected in the nip portion and a leading edge position of a medium next to the preceding medium.
A control program characterized by: