Media supply device, media supply method, and control program

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

Technical Field

[0001] The present disclosure relates to a medium feeding device, a medium feeding method, and a control program, and particularly to a medium feeding device, a medium feeding method, and a control program having a feeding roller and a separating roller.

Background Art

[0002] In a medium conveyance device such as a scanner that sequentially feeds and images a plurality of media while separating them, it is required to suppress the occurrence of double feeding of the media in which a plurality of media are fed together.

[0003] A paper feeding device is disclosed that has a sheet number sensor that detects the number of sheets in the nip portion between the conveyance roller and the separating roller or downstream thereof, and a sheet position sensor that detects the position of the sheet coming out on the downstream side of the nip portion (see Patent Document 1). When two sheets are detected by the sheet number sensor, this paper feeding device controls the pressing load or separating torque of the separating roller so that the position of the second sheet detected by the sheet position sensor becomes the target value.

[0004] A sheet conveyance device is disclosed that separates the sheets double-fed and fed out from a sheet bundle at a separating nip portion between a paper feeding roller and a separating roller and conveys them one by one (see Patent Document 2). This sheet conveyance device images the next sheet separated by the separating roller with an area sensor, and acquires the protruding amount of the tip of the next sheet from the separating nip portion by detecting the leading edge from the image data. The sheet conveyance device determines the deterioration state of the separating roller based on the protruding amount of the next sheet, and displays a warning according to the determination result.

[0005] A sheet feeding device is disclosed that includes a feeding rotating body for feeding a sheet placed on a mounting section, a size detection means for detecting the size of the sheet in the width direction, and a tip detection means for detecting the tip of the sheet passing through the nip region of the first and second members (see Patent Document 3). In this sheet feeding device, if the sheet being fed by the feeding rotating body passes through the detection area of ​​the tip detection means, according to the sheet size detected by the size detection means, the feeding rotating body is moved to a retracted position based on that detection. If the sheet being fed does not pass through the detection area, the sheet feeding device is moved to a retracted position after a predetermined time has elapsed from the start of sheet feeding by the feeding rotating body. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2005-350239 [Patent Document 2] Japanese Patent Publication No. 2016-104663 [Patent Document 3] Japanese Patent Publication No. 2017-1878 [Overview of the Initiative]

[0007] Media feeding devices are required to appropriately suppress the occurrence of double feeding of media.

[0008] The media feeding device, media feeding method, and control program according to this embodiment aim to appropriately suppress the occurrence of double feeding of media.

[0009] A media 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, a separation roller positioned opposite the feeding roller, a detection unit that detects the leading edge position of the media at the nip portion of the feeding roller and the separation roller, and the separation roller The torque value or the pressing force that presses the separation roller toward the feed roller Attribute values asThe system includes a setting unit, which changes the characteristic value according to the distance between media, between the leading edge position of the preceding medium detected by the detection unit within the nip section and the leading edge position of the next medium following the preceding medium.

[0010] A media feeding method according to one aspect of the embodiment involves sequentially feeding multiple media placed on a mounting table using a feeding roller, detecting the leading edge position of the media at the nip portion of the feeding roller and the separation roller positioned opposite the feeding roller, and the separation roller The torque value or the pressing force that presses the separation roller toward the feed roller Attribute values as This includes setting the characteristic value, which changes the characteristic value according to the distance between media, specifically between the leading edge position of the preceding media detected within the nip portion and the leading edge position of the next media following the preceding media.

[0011] A control program relating to one aspect of the embodiment is a control program for a media feeding device having a mounting table, a feeding roller that sequentially feeds a plurality of media placed on the mounting table, and a separation roller positioned opposite the feeding roller, wherein the program detects the leading edge position of the media at the nip portion of the feeding roller and the separation roller, and the separation roller The torque value or the pressing force that presses the separation roller toward the feed roller Attribute values as The media feeding device is instructed to perform the setting, and during the setting process, the characteristic value is changed according to the media-to-media distance between the leading edge position of the preceding media detected within the nip section and the leading edge position of the next media following the preceding media.

[0012] According to this embodiment, the media feeding device, media feeding method, and control program can appropriately suppress the occurrence of double feeding of media.

[0013] The object and effect of the present invention will be recognized and obtained, in particular, by using the components and combinations indicated in the claims. Both the general description above and the detailed description below are illustrative and descriptive, and do not limit the present invention as described in the claims. [Brief explanation of the drawing]

[0014] [Figure 1]It is a perspective view showing a media feeding device 100 according to an embodiment. [Figure 2] It is a diagram for explaining a conveyance path inside the media feeding device 100. [Figure 3] It is a schematic diagram for explaining the first imaging device 115 and the like. [Figure 4] It is a schematic diagram for explaining the drive mechanism 130. [Figure 5] It is a block diagram showing a schematic configuration of the media feeding device 100. [Figure 6] It is a diagram showing a schematic configuration of the storage device 150 and the processing circuit 160. [Figure 7] It is a flowchart showing an example of the operation of the media reading process. [Figure 8] It is a flowchart showing an example of the operation of the setting process. [Figure 9] (A) and (B) are schematic diagrams showing an example of an input image. [Figure 10] (A) and (B) are schematic diagrams showing an example of an input image. [Figure 11] It is a flowchart showing another example of the operation of the setting process. [Figure 12] It is a flowchart showing another example of the operation of the setting process. [Figure 13] (A) and (B) are schematic diagrams showing an example of a second input image. [Figure 14] It is a diagram showing a schematic configuration of another processing circuit 260.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, a media feeding device, a media feeding method, and a control program according to one aspect of the present disclosure will be described with reference to the drawings. However, note that the technical scope of the present invention is not limited to those embodiments, and extends to the invention described in the claims and its equivalents.

[0016] Figure 1 is a perspective view showing a media feeding device 100 configured as an image scanner. The media feeding device 100 feeds and transports the medium, which is the original document, and takes an image of it. The medium can be paper, thin paper, thick paper, card, or booklet. The media feeding device 100 may also be a facsimile, copier, or multifunction printer (MFP, Multifunction Peripheral). Note that the transported medium may not be an original document but a print target, and the media feeding device 100 may be a printer, etc.

[0017] The media supply and transport device 100 includes a lower housing 101, an upper housing 102, a mounting table 103, a discharge table 104, an operating device 105, and a display device 106, etc. In Figure 1, arrow A1 indicates the media transport direction, arrow A2 indicates the width direction perpendicular to the media transport direction, and arrow A3 indicates the height direction perpendicular to the media transport path. Hereafter, "upstream" refers to the upstream of the media transport direction A1, and "downstream" refers to the downstream of the media transport direction A1.

[0018] The upper housing 102 is positioned to cover the top surface of the media supply device 100 and is engaged with the lower housing 101 by a hinge so that it can be opened and closed when the media is jammed, when cleaning the inside of the media supply device 100, etc.

[0019] The mounting platform 103 engages with the lower housing 101 and places the medium to be fed and transported on it. The discharge platform 104 engages with the upper housing 102 and places the discharged medium on it. The discharge platform 104 may also engage with the lower housing 101.

[0020] The operating device 105 has input devices such as buttons and an interface circuit that acquires signals from the input devices, accepts input operations from the user, and outputs an operation signal corresponding to the user's input operation. The display device 106 has a display including liquid crystal, organic EL (Electro-Luminescence), etc. and an interface circuit that outputs image data to the display, and displays the image data on the display.

[0021] Figure 2 is a diagram illustrating the transport path inside the media supply device 100.

[0022] The transport path inside the media supply device 100 includes a first media sensor 111, a supply roller 112, a separation roller 113, a light source device 114, a first imaging device 115, a pressing mechanism 116, a second media sensor 117, a first transport roller 118, a first driven roller 119, a third media sensor 120, a second imaging device 121, a second transport roller 122, and a second driven roller 123, among others.

[0023] Note that the number of each of the feeding rollers 112, separating rollers 113, first transport rollers 118, first driven rollers 119, second transport rollers 122 and / or second driven rollers 123 is not limited to one, but may be multiple. In that case, the multiple feeding rollers 112, separating rollers 113, first transport rollers 118, first driven rollers 119, second transport rollers 122 and / or second driven rollers 123 are arranged side by side with spacing between them in the width direction A2 perpendicular to the media transport direction.

[0024] The upper surface of the lower housing 101 forms the lower guide 101a of the media transport path, and the lower surface of the upper housing 102 forms the upper guide 102a of the media transport path. The media feeding device 100 has a so-called straight path and feeds and transports the media placed on the mounting table 103 from the bottom up, and discharges it to the discharge table 104.

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

[0026] The feed roller 112 is provided on the lower housing 101. The feed roller 112 is rotatable in the media feeding direction A4 and separates and feeds multiple media placed on the mounting table 103 from the bottom up. The separation roller 113 is a so-called brake roller or retard roller and is provided on the upper housing 102 and is positioned opposite the feed roller 112. The separation roller 113 is rotatable or stationary in the opposite direction A5 of the media feeding direction.

[0027] The pressing mechanism 116 is an example of a pressing section that presses the separation roller 113 toward the feed roller 112. The pressing mechanism 116 is provided so that the pressing force that presses the separation roller 113 toward the feed roller 112 can be adjusted. The pressing mechanism 116 includes an elastic member 116a, a support member 116b, and a drive device 116c, etc.

[0028] The elastic member 116a is, for example, a spring member such as a torsion coil spring. Alternatively, the elastic member 116a may be another spring member such as a compression coil spring, or a rubber member. 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 feed roller 112.

[0029] The support member 116b is provided to support the elastic member 116a. The support member 116b is provided so as to be movable in accordance with the driving force generated by the drive device 116c.

[0030] The drive device 116c is, for example, a solenoid. Alternatively, the drive device 116c may be a motor. The drive device 116c generates a driving force to adjust the pressing force applied by the elastic member 116a to press the separation roller 113 toward the feed roller 112, based on a control signal from a processing circuit described later. If the drive device 116c is a solenoid, the support member 116b slides in accordance with the linear movement of the movable magnetic pole of the solenoid, adjusting the pressing force applied by the elastic member 116a. If the drive device 116c is a motor, the support member 116b oscillates in accordance with the rotation of the motor, adjusting the pressing force applied by the elastic member 116a. If the drive device 116c is a motor, a rack and pinion may be provided between the drive device 116c and the support member 116b, and the support member 116b may slide in accordance with the rotation of the motor, adjusting the pressing force applied by the elastic member 116a.

[0031] The second medium sensor 117 is positioned downstream of the feed roller 112 and upstream of the first transport roller 118, and detects the medium transported to that position. The second medium sensor 117 includes a light emitter and a light receiver provided on one side of the medium transport path, and a light guide tube provided opposite the light emitter and light receiver across the medium transport path. The light emitter is an LED (Light Emitting Diode) or the like, and emits light toward the medium transport path. The light receiver, on the other hand, is a photodiode or the like, and receives the light emitted by the light emitter and guided by the light guide tube. When medium is present at a position opposite 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 and outputs a second medium signal whose signal value changes depending on whether medium is present or absent at the position of the second medium sensor 117, based on the intensity of the light received by the light receiver.

[0032] In addition, a reflective material such as a mirror may be used instead of the light guide tube. Furthermore, the light emitter and light receiver may be provided opposite each other across the medium transport path. The second medium sensor 117 may also detect the presence of the medium by using a contact detection sensor or the like that which supplies a predetermined current when the medium is in contact or when the medium is not in contact.

[0033] The first transport roller 118 and the first driven roller 119 are arranged facing each other downstream of the feeding roller 112 and the separation roller 113 in the media transport direction A1. The first transport roller 118 is provided on the upper housing 102 and transports the media fed by the feeding roller 112 and the separation roller 113 to the second imaging device 121. Alternatively, the first transport roller 118 may be provided on the lower housing 101 and the first driven roller 119 may be provided on the upper housing 102.

[0034] The third medium sensor 120 is positioned downstream of the first transport roller 118 and upstream of the second imaging device 121, and detects the medium being transported to its position. The third medium sensor 120 includes a light emitter and a light receiver provided on one side of the medium transport path, and a light guide tube provided opposite the light emitter and light receiver across the medium transport path. The light emitter is an LED or the like, and emits light toward the medium transport path. The light receiver, on the other hand, 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 and outputs a third medium signal whose signal value changes depending on whether a medium is present or absent at the position of the third medium sensor 120, based on the intensity of the light received by the light receiver.

[0035] Furthermore, a reflective material such as a mirror may be used instead of the light guide tube. Also, the light emitter and light receiver may be provided opposite each other across the medium transport path. In addition, the third medium sensor 120 may detect the presence of the medium by using a contact detection sensor or the like that which supplies a predetermined current when the medium is in contact or when the medium is not in contact.

[0036] The second imaging device 121 is positioned downstream of the first transport roller 118 and upstream of the second transport roller 122 in the medium transport direction A1, and images the medium transported by the first transport roller 118 and the first driven roller 119. The second imaging device 121 includes a front imaging device 121a and a back imaging device 121b, which are positioned opposite each other across the medium transport path.

[0037] The surface imaging device 121a has a line sensor using a 1:1 optical system type CIS (Contact Image Sensor) with CMOS (Complementary Metal Oxide Semiconductor) image sensors arranged linearly in the main scanning direction. The surface imaging device 121a also has a lens that forms an image on the image sensor and an A / D converter that amplifies the electrical signal output from the image sensor and performs analog-to-digital (A / D) conversion. The surface imaging device 121a captures the surface of the transported medium according to control from a processing circuit described later, generates a medium image, and outputs it.

[0038] Similarly, the back-side imaging device 121b has a line sensor with a CIS of the 1:1 optical system type, which has CMOS image sensors arranged linearly in the main scanning direction. The back-side imaging device 121b also has a lens that forms an image on the image sensor and an A / D converter that amplifies the electrical signal output from the image sensor and performs analog-to-digital (A / D) conversion. The back-side imaging device 121b captures the back surface of the transported medium according to control from a processing circuit described later, generates a medium image, and outputs it.

[0039] Furthermore, 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. Also, instead of a CIS line sensor of the 1:1 optical system type equipped with a CMOS image sensor, a CIS line sensor of the 1:1 optical system type equipped with a CCD (Charge Coupled Device) image sensor may be used. Alternatively, a reduction optical system type line sensor equipped with a CMOS or CCD image sensor may be used.

[0040] The second transport roller 122 and the second driven roller 123 are arranged facing each other in the media transport direction A1, downstream from the second imaging device 121, that is, downstream from the first transport roller 118 and the first driven roller 119. The second transport roller 122 is provided on the upper housing 102 and further transports the media transported by the first transport roller 118 and the first driven roller 119 downstream and discharges it to the discharge table 104. Alternatively, the second transport roller 122 may be provided on the lower housing 101 and the second driven roller 123 on the upper housing 102.

[0041] The media placed on the mounting table 103 is transported between the lower guide 101a and the upper guide 102a toward the media transport direction A1 by the feeding roller 112 rotating in the media transport direction A4. The media feeding device 100 has two feeding modes: a separation mode in which the media is fed while being separated, and a non-separation mode in which the media is fed without being separated. The feeding mode is set by the user using the operating device 105 or an information processing device that communicates with the media feeding device 100. When the feeding mode is set to separation mode, the separation roller 113 rotates or stops in the opposite direction A5 of the media transport direction. Due to the action of the feeding roller 112 and the separation roller 113, when multiple media are placed on the mounting table 103, only the media that are in contact with the feeding roller 112 among the media placed on the mounting table 103 are separated. This restricts the transport of media other than the separated media (preventing 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 (opposite direction of arrow A5).

[0042] The medium is fed between the first transport roller 118 and the first driven roller 119, guided by the lower guide 101a and the upper guide 102a. The first transport roller 118 and the first driven roller 119 rotate in forward directions A6 and A7, respectively, feeding the medium 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 platform 104 as the second transport roller 122 and the second driven roller 123 rotate in the directions of arrows A8 and A9, respectively.

[0043] Figure 3 is a schematic diagram illustrating the light source device 114 and the first imaging device 115. Figure 3 is a schematic diagram of the area around the media transport path as seen from the upper housing 102 side.

[0044] In the example shown in Figure 3, the feeding roller 112, separating roller 113, first conveying roller 118, first driven roller 119, second conveying roller 122, and second driven roller 123 are arranged in pairs.

[0045] The light source device 114 includes a first light source device 114a and a second light source device 114b.

[0046] The first light source device 114a is an example of an illumination unit. The first light source device 114a is positioned in the upper housing 102 upstream of the nip portion N of the feed roller 112 and the separation roller 113 in the media transport direction A1, and between the nip portions N of the two sets of feed rollers 112 and the separation roller 113 in the width direction A2. 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 the region that overlaps with the nip portion N when viewed from the width direction A2 which is perpendicular to the media transport direction, that is, the region that overlaps with the nip portion N in the media transport direction A1. The first light source device 114a illuminates the region between the two nip portions N in the width direction A2.

[0047] The second light source device 114b is an example of a second irradiation unit. The second light source device 114b is positioned in the upper housing 102 upstream of the nip portion N of the feed roller 112 and the separation roller 113 in the media transport direction A1, and between the nip portions N of the two sets of feed rollers 112 and the separation roller 113 in the width direction A2. The second light source device 114b is an LED or the like, and irradiates light downward and downstream. The second light source device 114b irradiates the region that overlaps with the nip portion N when viewed from the width direction A2 perpendicular to the media transport direction, that is, the region that overlaps with the nip portion N in the media transport direction A1, from a different direction than the first light source device 114a. The second light source device 114b irradiates the region between the two nip portions N in the width direction A2, similar to the first light source device 114a.

[0048] The second light source device 114b is positioned upstream of the first light source device 114a in the media transport direction A1. That is, the angle between the direction of light irradiation by the second light source device 114b and the media transport path is smaller than the angle between the direction of light irradiation by the first light source device 114a and the media transport path. For example, the first light source device 114a is provided such that the angle between the direction of light irradiation and the media transport path is 45° or more and less than 90°, and the second light source device 114b is set such that the angle between the direction of light irradiation and the media transport path is less than 45° and greater than 0°.

[0049] The first imaging device 115 is an example of an imaging unit. The first imaging device 115 is positioned in the upper housing 102 downstream of the nip portions N of the feed roller 112 and the separation roller 113 in the medium transport direction A1, and between the nip portions N of the two sets of feed rollers 112 and the separation roller 113 in the width direction A2. The first imaging device 115 has a reduction optical system type imaging sensor having two-dimensionally arranged CCD image sensors. The first imaging device 115 also has a lens that forms an image on the image sensor and an A / D converter that amplifies the electrical signal output from the image sensor and performs analog / digital (A / D) conversion. The first imaging device 115 generates an input image that captures the leading edge position of the transported medium in a region that overlaps with the nip portions N when viewed from the width direction A2 perpendicular to the medium transport direction, and in the region between the two nip portions N in the width direction A2.

[0050] Furthermore, instead of a reduction optical system type image sensor equipped with a CCD image sensor, a reduction optical system type image sensor equipped with a CMOS image sensor may be used. Alternatively, a 1:1 optical system type image sensor equipped with a CCD or CMOS image sensor may be used. In addition, instead of an image sensor with two-dimensionally arranged image sensors, an image sensor (line sensor) with one-dimensionally arranged image sensors along the width direction A2 may be used. In this case, the first imaging device 115 generates line images of predetermined positions on the supplied medium at regular intervals, and generates an input image by combining multiple line images.

[0051] 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. The medium feeding device 100 can appropriately detect the state of the leading edge of the medium regardless of its position within the imaging range of the first imaging device 115 by using a two-dimensional input image that includes the region between the two nip portions N. By detecting the state of the leading edge of the medium using a single input image generated at a predetermined timing, the medium feeding device 100 can detect the state of the leading edge of the medium with less overhead compared to continuously monitoring the leading edge of the medium at a predetermined position (point). 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, it can suppress increases in equipment cost and equipment size.

[0052] Furthermore, the first imaging device 115 can generate an input image in which the leading edge of the medium is captured more clearly by imaging from the downstream side to the upstream side. However, the medium being 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 in the input image. In response to this, the first light source device 114a can irradiate light from the upstream side to the downstream side, thereby forming a good shadow of the leading edge of the medium when viewed from the first imaging device 115 side, and clearly including the leading edge of the medium in the input image. In addition, the second light source device 114b can irradiate light from a different direction than the first light source device 114a, thereby forming a shadow of a different thickness on the leading edge of the medium than the shadow formed by the first light source device 114a. Therefore, the medium feeding device 100 can detect the state of the leading edge of the medium with high accuracy by utilizing the difference in the thickness of the shadows of the leading edge of the medium formed by the first light source device 114a and the second light source device 114b.

[0053] Figure 4 is a schematic diagram illustrating the drive mechanism 130 of the separation roller 113. Figure 4 is a schematic diagram of the area around the separation roller 113 inside the upper housing 102, viewed from above.

[0054] As shown in Figure 4, the drive mechanism 130 includes a first motor 131, first to sixth gears 132a to f, first to fourth electromagnetic clutches 133a to d, and first to fourth torque limiters 134a to d, etc.

[0055] The first motor 131 is connected to the separation roller 113 via the first to sixth gears 132a to f and the shaft 113a, and drives the separation roller 113. The first motor 131 generates a driving force to rotate the separation roller 113 in response to a control signal from the processing circuit, causing the separation roller 113 to separate and feed the medium. The first motor 131 is a DC motor, such as a brushed DC (Direct Current) motor. The first motor 131 may also be another DC motor, such as a brushless DC motor, or a stepping motor. The first motor 131 is provided so that the torque setting can be changed according to the supplied power.

[0056] The greater the amount of current supplied to the DC motor or stepping motor, that is, the greater the amount of 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 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 can increase the torque of the first motor 131 by increasing the amount of power supplied to the first motor 131, thereby increasing the torque applied to the separation roller 113 (the load component applied by the separation roller 113 to the medium). On the other hand, the medium feeding device 100 can decrease the torque of the first motor 131 by decreasing the amount of power supplied to the first motor 131, thereby decreasing the torque applied to the separation roller 113 (the load component applied by the separation roller 113 to the medium).

[0057] The first gear 132a is attached to the rotating shaft of the first motor 131. The first gear 132a is meshed with the second gear 132b, the second gear 132b with the third gear 132c, the third gear 132c with the fourth gear 132d, the fourth gear 132d with the fifth gear 132e, and the fifth gear 132e with the sixth gear 132f. The sixth gear 132f is attached to one end of the shaft 113a, which is the rotating shaft of the separation roller 113.

[0058] The first electromagnetic clutch 133a is attached to the shaft which is the rotation axis of the second gear 132b, and the first torque limiter 134a is attached to the shaft which is the rotation axis of the second gear 132b via the first electromagnetic clutch 133a. The first torque limiter 134a defines the torque limit value applied to the separation roller 113 by defining the torque limit value applied to the second gear 132b. The limit value of the first torque limiter 134a is set such that the torque limit value applied to the separation roller 113 becomes the first limit value when only the first torque limiter 134a is connected to the separation roller 113. 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 micropowder clutch, which connects or disconnects the power between the second gear 132b and the first torque limiter 134a according to a control signal from the processing circuit.

[0059] The second electromagnetic clutch 133b is attached to the shaft which is the rotation axis of the third gear 132c, and the second torque limiter 134b is attached to the shaft which is the rotation axis of the third gear 132c via the second electromagnetic clutch 133b. The second torque limiter 134b defines the torque limit value applied to the separation roller 113 by defining the torque limit value applied to the third gear 132c. The limit value of the second torque limiter 134b is set so that when only the second torque limiter 134b is connected to the separation roller 113, the torque limit value applied to the separation roller 113 becomes the second limit value. That is, the limit value of the second torque limiter 134b is set so 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 micropowder clutch, which connects or disconnects the power between the third gear 132c and the second torque limiter 134b according to a control signal from the processing circuit.

[0060] The third electromagnetic clutch 133c is attached to the shaft which is the rotation axis of the fourth gear 132d, and the third torque limiter 134c is attached to the shaft which is the rotation axis of the fourth gear 132d via the third electromagnetic clutch 133c. The third torque limiter 134c defines the torque limit value applied to the separation roller 113 by defining the torque limit value applied to the fourth gear 132d. The limit value of the third torque limiter 134c is set so that the torque limit value applied to the separation roller 113 becomes the third limit value when only the third torque limiter 134c is connected to the separation roller 113. That is, the limit value of the third torque limiter 134c is set so 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 micropowder clutch, which connects or disconnects the power between the fourth gear 132d and the third torque limiter 134c according to a control signal from the processing circuit.

[0061] The fourth electromagnetic clutch 133d is attached to the shaft which is the rotation axis of the fifth gear 132e, and the fourth torque limiter 134d is attached to the shaft which is the rotation axis of the fifth gear 132e via the fourth electromagnetic clutch 133d. The fourth torque limiter 134d defines the torque limit value applied to the separation roller 113 by defining the torque limit value applied to the fifth gear 132e. The limit value of the fourth torque limiter 134d is set so that the torque limit value applied to the separation roller 113 becomes the fourth limit value when only the fourth torque limiter 134d is connected to the separation roller 113. That is, the limit value of the fourth torque limiter 134d is set so 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 micropowder clutch, which connects or disconnects the power between the fifth gear 132e and the fourth torque limiter 134d according to a control signal from the processing circuit.

[0062] When the first to fourth electromagnetic clutches 133a to d are coupled to the power, the torque applied to the second to fifth gears 132b to e is limited by the first to fourth torque limiters 134a to d, respectively. On the other hand, when the first to fourth electromagnetic clutches 133a to d are disengaged from the power, the torque applied to the second to fifth gears 132b to e is not limited by the first to fourth torque limiters 134a to d, respectively.

[0063] The torque limit values ​​applied to the separation roller 113 are examples of the torque values ​​of the separation roller 113 and examples of the characteristic values ​​of the separation roller 113. The first limit value, second limit value, third limit value, and fourth limit value are examples of the first torque value, second torque value, third torque value, and fourth torque value, respectively.

[0064] The first, second, third, and fourth limit values ​​are set such that when only one medium is being fed, the transmission of the first drive force from the first motor 131 is interrupted, and when multiple mediums are being fed, the first drive force from the first motor 131 is transmitted. As a result, when only one medium is being fed, the separation roller 113 does not rotate according to the drive 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 exceeding the limit value is applied. On the other hand, when multiple mediums are being fed, the separation roller 113 rotates in the opposite direction A5 to the medium feeding direction, separating the medium in contact with the feeding roller 112 from the other medium, thereby preventing double feeding. At this time, the outer surface of the separation roller 113 may remain stationary without rotating in the opposite direction A5 to the medium feeding direction, and a force in the opposite direction A5 to the medium feeding direction may be applied to the medium.

[0065] The limit value of the second torque limiter 134b is set to a value greater 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 less than the limit value of the second torque limiter 134b. The limit value of the fourth torque limiter 134d is set to the same value as the limit value of the second torque limiter 134b or a value greater than the limit value of the second torque limiter 134b. In addition, the limit values ​​of the first to fourth torque limiters 134a to d are set to a value less than the torque of the first motor 131. That is, the second limit value is set to a value greater than the first limit value. The third limit value is set to a value greater than the first limit value and less than the second limit value. The fourth limit value is set to the second limit value or a value greater than the second limit value. The medium feeding device 100 can change the torque limit value applied to the separation roller 113 by controlling the first to fourth electromagnetic clutches 133a to d.

[0066] In the following, the first to fourth electromagnetic clutches 133a to d may be collectively referred to as electromagnetic clutch 133. Note that electromagnetic clutch 133 may be replaced by other types of clutches, such as hysteresis clutches. Furthermore, an electromagnetic brake such as a micropowder brake or hysteresis brake may be used instead of electromagnetic clutch 133.

[0067] Figure 5 is a block diagram showing the schematic configuration of the media supply device 100.

[0068] In addition to the configuration described above, the media supply device 100 further includes a second motor 141, a third motor 142, an interface device 143, a storage device 150, and a processing circuit 160.

[0069] The second motor 141 rotates the feed roller 112 in response to a control signal from the processing circuit 160 to feed the medium.

[0070] The third motor 142 rotates the first transport roller 118 and the second transport roller to transport the medium, based on a control signal from the processing circuit 160. The first driven roller 119 and / or the second driven roller 123 may be provided to be driven by the driving force from the third motor 142.

[0071] The interface device 143 has an interface circuit similar to a serial bus such as USB, and electrically connects to an information processing device (not shown) (e.g., a personal computer, a portable information terminal, etc.) to transmit and receive input images and various types of information. Alternatively, instead of the interface device 143, a communication unit may be used that has an antenna for transmitting and receiving wireless signals and a wireless communication interface device for transmitting and receiving signals via a wireless communication line according to a predetermined communication protocol. The predetermined communication protocol is, for example, a wireless LAN (Local Area Network). The communication unit may also have a wired communication interface device for transmitting and receiving signals via a wired communication line according to a communication protocol such as a wired LAN.

[0072] The storage device 150 includes memory devices such as RAM (Random Access Memory) and ROM (Read Only Memory), fixed disk devices such as hard disks, or portable storage devices such as flexible disks and optical disks. The storage device 150 also stores computer programs, databases, tables, etc., used for various processes of the media supply device 100. The computer programs may be installed into the storage device 150 from a computer-readable portable recording medium using a known setup program. Examples of portable recording media include CD-ROMs (compact disc read-only memory) and DVD-ROMs (digital versatile disc read-only memory).

[0073] The processing circuit 160 operates based on a program pre-stored in the memory device 150. The processing circuit is, for example, a CPU (Central Processing Unit). A DSP (digital signal processor), LSI (large scale integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), etc., may be used as the processing circuit 160.

[0074] The processing circuit 160 is connected to the operating device 105, display device 106, first medium sensor 111, light source device 114, first imaging device 115, second medium sensor 117, third medium sensor 120, second imaging device 121, drive device 116c, first motor 131, electromagnetic clutch 133, second motor 141, third motor 142, interface device 143, and storage device 150, and controls each of these parts. Based on the medium signals received from each medium sensor, the processing circuit 160 performs drive control of each motor, imaging control of the second imaging device 121, etc. 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. In addition, the processing circuit 160 detects the leading edge position of the medium in the nip section N based on the input image acquired from the first imaging device 115, and sets the characteristic value of the separation roller 113 based on the detection result.

[0075] Figure 6 shows a schematic configuration of the storage device 150 and the processing circuit 160.

[0076] As shown in Figure 6, the storage device 150 stores control programs 151, detection programs 152, and setting programs 153, etc. Each of these programs is a functional module implemented by software running on the processor. The processing circuit 160 reads each program stored in the storage device 150 and operates according to each program it has read. In this way, the processing circuit 160 functions as a control unit 161, a detection unit 162, and a setting unit 163.

[0077] Figure 7 is a flowchart showing an example of the operation of the media reading process of the media supply device 100.

[0078] The following describes an example of the operation of the media reading process of the media supply device 100, referring to the flowchart shown in Figure 7. The operation flow described below is mainly executed by the processing circuit 160 in cooperation with each element of the media supply device 100, based on a program pre-stored in the storage device 150.

[0079] First, the control unit 161 waits until the user inputs an instruction to read the medium using the operating device 105 or the information processing device, and receives an operation signal instructing the reading of the medium from the operating device 105 or the interface device 143 (step S101).

[0080] Next, the control unit 161 acquires a 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 terminates the series of steps.

[0081] On the other hand, if a medium is placed on the mounting table 103, the processing circuit 160 performs a setting process (step S103). In the setting process, the processing circuit 160 detects the leading edge position of the medium at the nip section 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.

[0082] Next, the control unit 161 drives the second motor 141 to rotate the feeding roller 112 and feed the medium, and drives the first motor 131 to rotate the separation roller 113 and separate the medium. The control unit 161 also drives the third motor 142 to rotate the first transport roller 118, the first driven roller 119, the second transport roller 122 and / or the second driven roller 123 to transport the medium (step S104). At this time, the separation roller 113 rotates according to the characteristic value set in the setting process in step S103, and the medium feeding device 100 can appropriately control the separation roller 113 according to the leading edge position of the medium placed on the mounting table 103 and appropriately separate the medium.

[0083] Next, the control unit 161 waits until the leading edge of the fed medium passes the nip portion of the first transport roller 118 and the first driven roller 119 (step S105). Hereinafter, the nip portion of the first transport roller 118 and the first driven roller 119 may be referred to as the transport portion. The control unit 161 periodically acquires a third medium signal from the third medium sensor 120, and determines that the leading edge of the medium has passed the position of the third medium sensor 120 when the signal value of the third medium signal changes from a value indicating the absence of medium to a value indicating the presence of medium. The control unit 161 determines that the leading edge of the medium has passed the transport portion when the leading edge of the medium has passed the position of the third medium sensor 120. Alternatively, the control unit 161 may determine that the leading edge of the medium has passed the transport portion after a predetermined time has elapsed since the start of medium feeding.

[0084] Next, the control unit 161 instructs the second imaging device 121 to start imaging the medium (step S106).

[0085] Next, the control unit 161 controls the second motor 141 to stop the feed roller 112 (step S107). As a result, the medium is then transported by the first transport roller 118 and the second transport roller 122, and the feed roller 112 is carried around by the transported medium. By stopping the feed roller 112, the control unit 161 can suppress the medium from being pushed by the feed roller 112, causing it to bend between the feed roller 112 and the first transport roller 118, and preventing the medium from jamming.

[0086] Next, the control unit 161 determines whether or not there is any medium remaining on the mounting tray 103 based on the first medium signal received from the first medium sensor 111 (step S108).

[0087] If there is still media remaining on the mounting table 103, the control unit 161 waits until the trailing end of the fed media passes the nip portion N of the feed roller 112 and the separation roller 113 (step S109). Hereinafter, the nip portion N of the feed roller 112 and the separation roller 113 may be referred to as the separation portion. The control unit 161 periodically acquires a second media signal from the second media sensor 117, and determines that the trailing end of the media has passed the position of the second media sensor 117 when the signal value of the second media signal changes from a value indicating the presence of media to a value indicating the absence of media. The control unit 161 determines that the trailing end of the media has passed the separation portion when the trailing end of the media has passed the position of the second media sensor 117. The control unit 161 may also determine that the trailing end of the media has passed the separation portion when a predetermined time has elapsed since the start of media feeding.

[0088] Next, the processing circuit 160 performs a setting process (step S110) in the same manner as the process in step S103.

[0089] Next, the control unit 161 drives the second motor 141 to re-rotate the feed roller 112 and feed the subsequent medium (step S111). That is, when the trailing end of the preceding medium passes the separation section, the control unit 161 re-rotates the feed roller 112 and starts feeding the subsequent medium. At this time, the separation roller 113 rotates according to the characteristic value set in the setting process of step S110, and the medium feeding device 100 can appropriately control the separation roller 113 according to the leading edge position of the medium placed on the mounting table 103 and appropriately separate the medium.

[0090] 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 determines that the rear end of the medium has passed the position of the third medium sensor 120 when the signal value of the third medium signal changes from a value indicating the presence of medium to a value indicating the absence of medium. 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. Alternatively, 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 start of medium feeding.

[0091] Next, the control unit 161 acquires a media image from the second imaging device 121 and outputs the acquired media image by transmitting it to the information processing device via the interface device 143 (step S113).

[0092] Next, the control unit 161 returns to step S105 and repeats the processing from step S105 onward for the subsequent medium.

[0093] On the other hand, if no medium remains on the mounting table 103 in step S108, the control unit 161 waits in the same manner as in step S112 until the rear end of the transported medium passes the imaging position of the second imaging device 121 (step S114).

[0094] Next, the control unit 161 acquires a media image from the second imaging device 121 and outputs the acquired media image by transmitting it to the information processing device via the interface device 143 (step S115).

[0095] Next, the control unit 161 waits until the trailing end of the conveyed medium passes the nip portion of the second conveyor roller 122 and the second driven roller 123 (step S116). Hereinafter, the nip portion of the second conveyor roller 122 and the second driven roller 123 may be referred to as the discharge portion. The control unit 161 determines that the trailing end of the medium has passed the discharge portion when a second predetermined time has elapsed since the trailing 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 portion. The control unit 161 may also determine that the trailing end of the medium has passed the discharge portion when a predetermined time has elapsed since the start of medium feeding.

[0096] Next, the control unit 161 controls the second motor 141 and the third motor 142 to stop the separation roller 113, the first transport roller 118, the first driven roller 119, the second transport roller 122 and / or the second driven roller 123 (step S117). With this, the control unit 161 completes the series of steps.

[0097] Figure 8 is a flowchart illustrating an example of the operation of the configuration process.

[0098] The setting process is performed in steps S103 and S110 of the media reading process shown in Figure 7.

[0099] First, the detection unit 162 acquires an input image from the first imaging device 115 (step S201). The detection unit 162 generates an input image by having the first imaging device 115 image the medium while illuminating the first light source device 114a and turning off the second light source device 114b. Alternatively, the detection unit 162 may generate an input image by having the first imaging device 115 image the medium while illuminating both the first light source device 114a and the second light source device 114b.

[0100] Figures 9(A), (B), and 10(A), (B) are schematic diagrams showing examples of input images P1, P2, P3, and P4, respectively.

[0101] Input images P1 to P4 each include two sets of feed rollers 112, a separation roller 113, and a nip section N, as well as the area between them, such that the media transport direction A1 coincides with the horizontal direction and the width direction A2 coincides with the vertical direction. Input images P1 to P4 also each include media M1, M2, and M3 placed on a mounting table 103. The media M1, M2, and M3 are placed from bottom to top in the order M1, M2, and M3. In input images P1 to P4, position C is the center position of the nip section N in the media transport direction A1, and positions F1 and F2 are the leading edge (downstream end) positions of media M1 and M2, respectively.

[0102] As described above, the setting process is performed before media feeding begins (step S103 in Figure 7), or after the leading edge of a preceding medium has passed the transport section and stopped the feed roller 112, and the trailing edge of that preceding medium has passed the separation section (step S110 in Figure 7). Before media feeding begins, when a user places multiple media on the loading platform 103, there is a possibility that each medium may be pushed into the separation section (nip section N), causing the leading edge of each medium to enter the separation section (nip section N). Also, after media feeding begins, when the trailing edge of a preceding medium has passed the separation section, there is a possibility that the leading edge of a following medium may be dragged along by the preceding medium and enter the separation section (nip section N).

[0103] In the input image P1, the leading edge position F1 of medium M1 is located upstream of the center position C, and the distance L between the leading edge position F1 of medium M1 and the leading edge position F2 of medium M2 is sufficiently large. In this case, the separation force applied by the separation roller 113 to mediums M1 and M2 is sufficiently long, and the separation force is applied separately to the leading edge of medium M1 and the leading edge of medium M2. Therefore, there is a high probability that mediums M1 and M2 will be separated well.

[0104] In input image P2, the leading edge position F1 of medium M1 is located upstream of the center position C, and the distance L between the leading edge position F1 of medium M1 and the leading edge position F2 of medium M2 is small. In this case, the separation force applied to mediums M1 and M2 by the separation roller 113 is sufficiently long, but the separation force is applied integrally to the leading edges of medium M1 and medium M2. Therefore, compared to the state shown in input image P1, mediums M1 and M2 become more difficult to separate.

[0105] In input image P3, the leading edge position F1 of medium M1 is located downstream of the center position C, and the distance L between the leading edge position F1 of medium M1 and the leading edge position F2 of medium M2 is sufficiently large. In this case, the separation force by the separation roller 113 is applied separately to the leading edges of medium M1 and medium M2, but the time for which the separation force by the separation roller 113 is applied to mediums M1 and M2 is short. Therefore, compared to the state shown in input image P1, mediums M1 and M2 are less likely to separate. However, in this case, mediums M1 and M2 are more likely to separate than in the state shown in input image P2.

[0106] In input image P4, the leading edge position F1 of medium M1 is located downstream of the center position C, and the distance L between the leading edge position F1 of medium M1 and the leading edge position F2 of medium M2 is small. In this case, the time during which the separation force by the separation roller 113 is applied to mediums M1 and M2 is short, and the separation force by the separation roller 113 is applied integrally to the leading edges of medium M1 and medium M2. Therefore, compared to the state shown in input images P1 to P3, mediums M1 and M2 become less likely to separate.

[0107] Next, the detection unit 162 detects the leading edge position of the media at the nip portion N of the feeding roller 112 and the separation roller 113 (step S202). Based on the acquired input image, the detection unit 162 detects the leading edge position of the preceding media (the media to be fed next) and the leading edge position of the media following the preceding media (the second media to be fed) at the nip portion N.

[0108] The media feeding device 100 pre-stores in the storage device 150 the positions of the two sets of feeding rollers 112, the separation roller 113, and the nip section N in the input image, as well as predetermined positions within each nip section N in the media transport direction A1. The predetermined position is, for example, the center position C of the nip section N in the media transport direction A1. The predetermined position may be any other position within the nip section N.

[0109] The detection unit 162 calculates the difference between the grayscale value of the pixel to the right of the pixel to the left of the pixel to the left of the pixel to the left of the pixel to the right of the pixel to the left of the pixel to the left of the pixel to the left of the pixel to the right of the pixel to the left of the pixel to the left of the pixel to the left of the medium transport direction A1 (horizontal direction). Hereinafter, this difference may be referred to as the adjacent difference value. The detection unit 162 detects pixels whose adjacent difference value exceeds the grayscale threshold as edge pixels. The grayscale value is a luminance value or a color value (R value, G value, or B value), etc. The grayscale threshold is set, for example, to a difference in luminance values ​​that a person can visually distinguish as a difference in luminance on the image (e.g., 20). That is, the detection unit 162 looks from the bottom edge and detects pixels as edge pixels where the luminance value changes from a high value (a color close to white) to a low value (a color close to black). The detection unit 162 detects the position of the first detected edge pixel, i.e., the edge pixel located furthest downstream, in the medium transport direction A1 as the leading edge position of the preceding medium. The detection unit 162 also detects the position of the second detected edge pixel, i.e., the edge pixel located second from the downstream side, in the medium transport direction A1 as the leading edge position of the medium following the preceding medium.

[0110] The detection unit 162 may also calculate the difference in grayscale values ​​between two pixels in the input image that are separated by a predetermined distance in the media transport direction A1 from each pixel, as an adjacent difference value. Alternatively, the detection unit 162 may detect edge pixels by comparing the grayscale value of each pixel in the input image with a threshold. For example, the detection unit 162 detects a specific pixel as an edge pixel if its grayscale value is above a threshold, and the grayscale value of a pixel adjacent to that specific pixel upstream or separated by a predetermined distance is below the threshold.

[0111] Next, the detection unit 162 detects the distance between media between the leading edge position of the preceding medium detected by the detection unit 162 within the nip section N and the leading edge position of the next medium following the preceding medium (step S203). The detection unit 162 calculates the number of pixels between the leading edge position of the preceding medium and the leading edge position of the next medium detected in the input image. The media feeding device 100 pre-sets a table in the storage device 150 that shows 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 the table pre-set in the storage device 150 and, based on the resolution of the input image, identifies the actual distance between the leading edge position of the preceding medium and the leading edge position of the next medium that corresponds to the calculated number of pixels.

[0112] Next, the detection unit 162 determines whether the leading edge position of the preceding medium is located downstream of a predetermined position within the nip section N in the medium transport direction A1 (step S204).

[0113] If the leading edge of the preceding medium is not located downstream of a predetermined position, i.e., located upstream, the detection unit 162 determines whether the distance between the leading edge of the preceding medium and the leading edge of the next medium is greater than or equal to a threshold (step S205). The threshold is predetermined to be the maximum or average value of the distance between media when double feeding of media occurs in a prior experiment in which various types of media are fed.

[0114] If the distance between media, between the leading edge position of the preceding medium and the leading edge position of the next medium following the preceding medium, is greater than or equal to a threshold, the setting unit 163 sets the torque limit value applied to the separation roller 113 to the first limit value (step S206) and ends the series of steps. 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 sets the other electromagnetic clutch to disconnect the power between the other gear and the other torque limiter. As a result, the setting unit 163 sets the torque limit value applied to the separation roller 113 to the first limit value and limits the load component applied by the separation roller 113 to the first limit value.

[0115] As shown in the input image P1, the setting unit 163 sets the torque limit value applied to the separation roller 113 to a first limit value when the leading edge position F1 of the preceding medium is located upstream of the predetermined position in the medium transport direction A1 and the distance L between the mediums is greater than or equal to a threshold value. The setting unit 163 sets the torque limit value applied to the separation roller 113 to a sufficiently small first limit value when there is a high probability that medium M1 and medium M2 will be separated well. This prevents the medium feeding device 100 from becoming too forceful in pinching the medium between the feeding roller 112 and the separation roller 113, thus preventing medium jamming.

[0116] On the other hand, if the distance between media between the leading edge position of the preceding medium and the leading edge position of the next medium is less than a threshold, the setting unit 163 sets the torque limit value applied to the separation roller 113 to the second limit value (step S207) and ends the series of steps. 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 sets the other electromagnetic clutch to disconnect the power between the other gear and the other torque limiter. As a result, the setting unit 163 sets the torque limit value applied to the separation roller 113 to the second limit value.

[0117] As shown in the input image P2, the setting unit 163 sets the torque limit value applied to the separation roller 113 to a second limit value when the leading edge position F1 of the preceding medium is located upstream of the predetermined position in the medium transport direction A1 and the distance L between the mediums is less than a threshold value. The setting unit 163 also sets the torque limit value applied to the separation roller 113 to a second limit value which is greater than the first limit value when the medium M1 and medium M2 are difficult to separate. As a result, the medium feeding device 100 can increase the separation force by the feeding roller 112 and the separation roller 113, thereby suppressing the occurrence of double feeding of the medium.

[0118] In step S204, if the leading edge position of the preceding medium is located downstream of a predetermined position, the detection unit 162 determines whether the distance between the leading edge position of the preceding medium and the leading edge position of the next medium is greater than or equal to a threshold (step S208).

[0119] If the distance between media, between the leading edge position of the preceding medium and the leading edge position of the next medium following the preceding medium, is greater than or equal to a threshold, the setting unit 163 sets the torque limit value applied to the separation roller 113 to the third limit value (step S209) and ends the series of steps. 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 sets the other electromagnetic clutches to disconnect the power between the other gears and the other torque limiters. As a result, the setting unit 163 sets the torque limit value applied to the separation roller 113 to the third limit value.

[0120] As shown in the input image P3, the setting unit 163 sets the torque limit value applied to the separation roller 113 to a third limit value when the leading edge position F1 of the preceding medium is located downstream of the predetermined position in the medium transport direction A1 and the distance L between the mediums is greater than or equal to a threshold value. The setting unit 163 also sets the torque limit value applied to the separation roller 113 to a third limit value that is greater than the first torque value and less than the second torque value when the medium M1 and medium M2 are slightly difficult to separate. As a result, the medium feeding device 100 can slightly increase the separation force by the feeding roller 112 and the separation roller 113, thereby suppressing the occurrence of medium jams and preventing double feeding of medium.

[0121] If the distance between media, between the leading edge position of the preceding medium and the leading edge position of the next medium following the preceding medium, is less than a threshold, the setting unit 163 sets the torque limit value applied to the separation roller 113 to the fourth limit value (step S210) and ends the series of steps. 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 sets the other electromagnetic clutches to disconnect the power between the other gears and the other torque limiters. As a result, the setting unit 163 sets the torque limit value applied to the separation roller 113 to the fourth limit value.

[0122] As shown in the input image P4, the setting unit 163 sets the torque limit value applied to the separation roller 113 to the fourth limit value when the leading edge position F1 of the preceding medium is located downstream of the predetermined position in the medium transport direction A1 and the distance L between the mediums is greater than or equal to a threshold value. The setting unit 163 also sets the torque limit value applied to the separation roller 113 to the fourth limit value, which is greater than the first, second, and third limit values, when the medium M1 and medium M2 are extremely difficult to separate. As a result, the medium feeding device 100 can drastically increase the separation force by the feeding roller 112 and the separation roller 113, thereby suppressing the occurrence of double feeding of the medium.

[0123] In this way, the setting unit 163 changes the torque limit value applied to the separation roller 113 according to the distance between media, between the leading edge position of the preceding media detected by the detection unit 162 within the nip section N and the leading edge position of the next media. The setting unit 163 also changes the torque limit value applied to the separation roller 113 according to whether the leading edge position F1 of the preceding media detected by the detection unit 162 is located downstream of a predetermined position in the media transport direction A1. As a result, the media feeding device 100 can suppress the occurrence of media jams while also suppressing the occurrence of double feeding of media.

[0124] Furthermore, the setting process is performed immediately before the rotation of the feed roller 112 begins (steps S105 and S111 in Figure 7). Specifically, the detection unit 162 detects the leading edge position of the medium immediately before the rotation of the feed roller 112 begins, and the setting unit 163 sets the characteristics of the separation roller 113 according to the detection result. As a result, 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 feeding begins, and the medium can be separated well.

[0125] Furthermore, steps S204, S208-S210 may be omitted, and the setting unit 163 may change the torque limit value applied to the separation roller 113 according only to the distance between media, regardless of the leading edge position F1 of the preceding media. Alternatively, steps S205, S207, S208, and S210 may be omitted, and the setting unit 163 may change the torque limit value applied to the separation roller 113 according only to the leading edge position F1 of the preceding media, regardless of the distance between media.

[0126] Furthermore, the detection unit 162 may use information other than the input image to detect the leading edge position of each medium in the nip section N. In that case, the medium feeding device 100 has multiple overlap sensors for detecting the overlap of the medium instead of the light source device 114 and the first imaging device 115. The multiple overlap sensors are arranged in the width direction A2 between the nip sections N of the two sets of feeding rollers 112 and the separation roller 113. The multiple overlap sensors are also arranged in a line with gaps between them at positions that overlap with the nip section N when viewed from the width direction A2, that is, at positions that overlap with the nip section N in the medium transport direction A1.

[0127] An 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 positioned near the transport path of the medium, facing each other across the transport path. The ultrasonic transmitter emits ultrasonic waves. On the other hand, the ultrasonic receiver receives the ultrasonic waves emitted by the ultrasonic transmitter and passing through the medium, and generates and outputs an ultrasonic signal, which is an electrical signal corresponding to the received ultrasonic waves. At the location where the medium is present, the ultrasonic waves emitted by the ultrasonic sensor are attenuated by the medium, so the signal value of the ultrasonic signal decreases. Furthermore, at the location where the medium overlaps, the ultrasonic waves emitted by the ultrasonic sensor are attenuated by the air layer between the multiple media, so the signal value of the ultrasonic signal decreases even further.

[0128] 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 output by each ultrasonic sensor is less than or equal to a first ultrasonic threshold, and whether it is less than or equal to a second ultrasonic threshold that is smaller than the first ultrasonic threshold. The first ultrasonic threshold is set to a value between, for example, the signal value of the ultrasonic signal detected when no medium is present and the signal value of the ultrasonic signal detected when one sheet of PPC paper is present. The second ultrasonic threshold is set to 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 transported.

[0129] The detection unit 162 detects the position of the downstream ultrasonic sensor whose output ultrasonic signal value is below the first ultrasonic threshold as the leading edge position of the preceding medium. The detection unit 162 also detects the position of the downstream ultrasonic sensor whose output ultrasonic signal value is below the second ultrasonic threshold as the leading edge position of the next medium following the preceding medium.

[0130] The overlap sensor may also be a thickness sensor. Each thickness sensor includes a light emitter and a light receiver. Each light emitter and light receiver are positioned near the transport path of the medium, facing each other across the transport path. The light emitter emits light (infrared or visible light) towards the light receiver. The light receiver receives the light emitted by the light emitter and generates and outputs a thickness signal, which is an electrical signal corresponding to the intensity of the received light. When a medium is present at the position of the thickness sensor, the light emitted by the light emitter is attenuated by the medium, and the greater the thickness of the medium, the greater the attenuation. For example, the thickness sensor generates a thickness signal such that the signal value increases as the thickness of the medium increases.

[0131] Furthermore, 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 light emitters and receivers provided on one side of the medium transport path, and a pair of light emitters and receivers provided on the other side. The reflected light sensor detects the distance between each pair and each surface of the medium from the time it takes for one pair to irradiate one surface of the medium with light and receive the reflected light, and the time it takes for the other pair to irradiate the other surface of the medium with light and receive the reflected light. The reflected light sensor generates a thickness signal that shows a subtracted value obtained by subtracting the detected distances from the distance between the two pairs. The pressure sensor detects the pressure that changes according to the thickness of the medium and generates a thickness signal that shows the detected pressure. The mechanical sensor detects the amount of movement of a roller in contact with the medium and generates a thickness signal that shows the detected amount of movement.

[0132] 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 a first thickness threshold, and whether it is less than or equal to a second thickness threshold that is greater than the first thickness threshold. The first thickness threshold is set to a value between, for example, 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. The second thickness threshold is set to 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 transported.

[0133] The detection unit 162 detects the position of the downstreammost thickness sensor among the thickness sensors whose output thickness signal value is equal to or greater than the first thickness threshold, as the leading edge position of the preceding medium. The detection unit 162 also detects the position of the downstreammost thickness sensor among the thickness sensors whose output thickness signal value is equal to or less than the second thickness threshold, as the leading edge position of the medium following the preceding medium.

[0134] 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.

[0135] In that case, in steps S206, S207, S209, and S210, the setting unit 163 changes the torque limit value applied to the separation roller 113 by changing the torque of the first motor 131 instead of changing the first to fourth electromagnetic clutches 133a to d. In step S206, the setting unit 163 sets the torque of the first motor 131 so that the torque limit value applied to the separation roller 113 becomes the first torque value, that is, so that the sum of the limit value of the torque limiter connected to the separation roller 113 and the torque of the first motor 131 becomes the first limit value. In step S207, the setting unit 163 sets the torque of the first motor 131 so that the torque limit value applied to the separation roller 113 becomes the second torque value, that is, so that the sum of the limit value of the torque limiter connected to the separation roller 113 and the torque of the first motor 131 becomes the second limit value. In step S209, the setting unit 163 sets the torque of the first motor 131 so that the limit value of the torque applied to the separation roller 113 becomes the third torque value, that is, so that the sum of the limit value of the torque limiter connected to the separation roller 113 and the torque of the first motor 131 becomes the third limit value. In step S210, the setting unit 163 sets the torque of the first motor 131 so that the limit value of the torque applied to the separation roller 113 becomes the fourth torque value, that is, so that the sum of the limit value of the torque limiter connected to the separation roller 113 and the torque of the first motor 131 becomes the fourth limit value.

[0136] 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.

[0137] As detailed above, the media feeding device 100 changes the torque value, which is a characteristic value of the separation roller 113, 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 of the feeding roller 112 and the separation roller 113. As a result, the media feeding device 100 can appropriately change the separation force by the separation roller 113 according to the feeding state (separation state) of the medium placed on the mounting table 103, thereby suppressing the occurrence of medium jams and the occurrence of double feeding of the medium. Therefore, the media feeding device 100 is able to appropriately suppress the occurrence of double feeding of the medium.

[0138] Figure 11 is a flowchart illustrating another example of how the configuration process works.

[0139] The flowchart shown in Figure 11 is executed instead of the flowchart shown in Figure 8. The processes in steps S301-S305 and S308 in Figure 11 are the same as the processes in steps S201-S205 and S208 in Figure 8, so their explanation is omitted, and only steps S306-S307 and S309-S310 will be explained below.

[0140] In step S306, the setting unit 163 sets the pressing force applied by the pressing mechanism 116 to press the separation roller 113 toward the feed roller 112 to 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 applied by the pressing mechanism 116 becomes the first pressing force. The pressing force applied by the pressing mechanism 116 to press the separation roller 113 toward the feed roller 112 is an example of the characteristic value of the separation roller 113.

[0141] Thus, the setting unit 163 sets the pressing force by the pressing mechanism 116 to the first pressing force when the leading edge position of the preceding medium is located upstream of a predetermined position within the nip section N, and the distance between the leading edge position of the preceding medium and the leading edge position of the next medium is greater than or equal to a threshold. The setting unit 163 sets the pressing force that presses the separation roller 113 toward the feeding roller 112 to a sufficiently large first pressing force when there is a high probability that multiple media will be separated well. As a result, the media feeding device 100 can firmly grip the media with the feeding roller 112 and the separation roller 113, thereby suppressing the occurrence of media jams.

[0142] In step S307, the setting unit 163 sets the pressing force applied by the pressing mechanism 116 to press the separation roller 113 toward the feed roller 112 to the second pressing force (step S307), and ends the series of steps. The second pressing force is set to a value smaller than the first pressing force. The setting unit 163 controls the drive unit 116c of the pressing mechanism 116 so that the pressing force applied by the pressing mechanism 116 becomes the second pressing force.

[0143] Thus, the setting unit 163 sets the pressing force by the pressing mechanism 116 to a second pressing force when the leading edge position of the preceding medium is located upstream of a predetermined position within the nip section N, and the distance between the leading edge position of the preceding medium and the leading edge position of the next medium is less than a threshold. The setting unit 163 also sets the pressing force that presses the separation roller 113 toward the feeding roller 112 toward a second pressing force, which is smaller than the first pressing force, when multiple media are difficult to separate. This makes it easier for the media feeding device 100 to return the media to the mounting table 103 toward the separation roller 113, thereby suppressing the occurrence of double feeding of media.

[0144] In step S309, the setting unit 163 sets the pressing force applied by the pressing mechanism 116 to press the separation roller 113 toward the feed roller 112 to the third pressing force (step S309), and ends the series of steps. The third pressing force is set to a value that is smaller than the first pressing force and larger than the second pressing force. The setting unit 163 controls the drive unit 116c of the pressing mechanism 116 so that the pressing force applied by the pressing mechanism 116 becomes the third pressing force.

[0145] Thus, the setting unit 163 sets the pressing force by the pressing mechanism 116 to a third pressing force when the leading edge position of the preceding medium is located downstream of a predetermined position within the nip section N, and the distance between the leading edge position of the preceding medium and the leading edge position of the next medium is greater than or equal to a threshold. When multiple media are slightly difficult to separate, the setting unit 163 sets the pressing force that presses the separation roller 113 toward the feeding roller 112 to a third pressing force that is smaller than the first pressing force and larger than the second pressing force. As a result, the media feeding device 100 can make it easier for the media to be slightly returned toward the mounting table 103 by the separation roller 113, thereby suppressing the occurrence of media jams and suppressing the occurrence of double feeding of media.

[0146] In step S310, the setting unit 163 sets the pressing force applied by the pressing mechanism 116 to press the separation roller 113 toward the feed roller 112 to the fourth pressing force (step S310), and ends the series of steps. The fourth pressing force is set to a value smaller than the second pressing force. The setting unit 163 controls the drive unit 116c of the pressing mechanism 116 so that the pressing force applied by the pressing mechanism 116 becomes the fourth pressing force.

[0147] Thus, the setting unit 163 sets the pressing force by the pressing mechanism 116 to the fourth pressing force when the leading edge position of the preceding medium is located downstream of a predetermined position within the nip section N, and the distance between the leading edge position of the preceding medium and the leading edge position of the next medium is less than a threshold. The setting unit 163 also sets the pressing force that presses the separation roller 113 toward the feeding roller 112 toward the fourth pressing force, which is smaller than the first, second, and third pressing forces, when multiple media are extremely difficult to separate. As a result, the media feeding device 100 can easily return the media toward the mounting table 103 toward the separation roller 113, thereby suppressing the occurrence of double feeding of media.

[0148] Note that, similar to the setting process in Figure 8, steps S304 and S308-S310, or steps S305, S307, S308 and S310, may be omitted. Also, the detection unit 162 may use an overlap sensor to detect the tip position of each medium in the nip portion N.

[0149] As described in detail above, the media feeding device 100 can appropriately suppress the occurrence of double feeding of media even when the pressing force applied by the pressing mechanism 116 to press the separation roller 113 toward the feeding roller 112 side according to the distance between the preceding medium and the next medium.

[0150] Figure 12 is a flowchart illustrating yet another example of how the configuration process works.

[0151] The flowchart shown in Figure 12 is executed instead of the flowchart shown in Figure 8. The processes in steps S401, S408-S409, and S411-S412 in Figure 12 are the same as the processes in steps S201, S206-S207, and S209-S210 in Figure 8, so their explanation is omitted, and only steps S402-S407 and S410 will be explained below.

[0152] In step S402, the detection unit 162 turns off the first light source device 114a and irradiates the second light source device 114b with light (step S402).

[0153] Next, the detection unit 162 acquires a second input image from the first imaging device 115 (step S403). That is, the detection unit 162 turns off the first light source device 114a and illuminates the second light source device 114b with light, causing the first imaging device 115 to image the medium and generate an input image.

[0154] Figures 13(A) and (B) are schematic diagrams showing examples of the second input images P5 and P6, respectively.

[0155] Similar to input images P1 to P4, the second input images P5 and P6 each include two sets of feeding rollers 112, a separating roller 113, and a nip section N, the area between them, and media M1, M2, and M3 placed on a mounting table 103. In the second input image P5, the leading edge position F1 of media M1 is located upstream of the center position C, and the distance between the leading edge position F1 of media M1 and the leading edge position F2 of media M2 is sufficiently large. On the other hand, in the second input image P6, the leading edge position F1 of media M1 is located upstream of the center position C, and the distance between the leading edge position F1 of media M1 and the leading edge position F2 of media M2 is small.

[0156] As described above, the angle between the direction of light irradiation by the second light source device 114b and the medium transport path is smaller than the angle between the direction of light irradiation by the first light source device 114a and the medium transport path. Therefore, the length T of the medium transport direction A1 of the shadows at the tips of each medium M1 and M2 in the second input image, which is captured with light irradiated only by the second light source device 114b, is longer than the length of the medium transport direction A1 of the shadows at the tips of each medium M1 and M2 in the input image. Consequently, as shown in the second input image P6, when the distance between the tips of medium M1 (F1) and medium M2 (F2) is small, the shadows at the tips of medium M1 and M2 connect.

[0157] Next, the detection unit 162 detects the leading edge position of the media at the nip portion N of the feeding roller 112 and the separation roller 113 (step S404). The detection unit 162 detects the leading edge position of the preceding media and the leading edge position of the media following the preceding media at the nip portion N from the input image and the second input image, respectively, in the same manner as the process in step S202 of Figure 8.

[0158] Next, the detection unit 162 detects the inter-medium distance between the leading edge position of the preceding medium detected by the detection unit 162 within the nip portion N and the leading edge position of the next medium following the preceding medium (step S405). The detection unit 162 determines the inter-medium distance between the leading edge position of the preceding medium and the leading edge position of the next medium based on the input image, in the same manner as the process in step S202 of Figure 8. Furthermore, the detection unit 162 determines the inter-medium distance between the leading edge position of the preceding medium and the leading edge position of the next medium based on the second input image.

[0159] The detection unit 162 detects edge pixels from the second input image in the same manner as the process in step S202 of Figure 8. The detection unit 162 also calculates the difference between the grayscale value of the pixel to the right of each pixel in the medium transport direction A1 (horizontal direction) at a specific position between two nip portions N in the width direction A2 (vertical direction) of the second input image, starting from the downstream end (left end). Hereinafter, this difference may be referred to as the second adjacent difference value. The detection unit 162 detects pixels whose adjacent difference value exceeds the grayscale threshold as second edge pixels. That is, the detection unit 162 detects pixels as second edge pixels when the brightness value changes from a low value (close to black) to a high value (close to white), starting from the bottom end. The detection unit 162 calculates the number of pixels between the first detected edge pixel and the second edge pixel.

[0160] The detection unit 162 refers to a table set in the storage device 150 that shows the relationship between the number of pixels in an image and the actual distance, and identifies the distance corresponding to the calculated number of pixels as the length of the shadow of the preceding medium. If the identified length of the shadow of the preceding medium is less than a threshold, the detection unit 162 determines that the shadow of the preceding medium and the shadow of the next medium are not connected, and that the distance between the leading edge of the preceding medium and the leading edge of the next medium is greater than or equal to the threshold. On the other hand, if the identified length of the shadow of the preceding medium is greater than or equal to 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 distance between the leading edge of the preceding medium and the leading edge of the next medium is less than a threshold.

[0161] Furthermore, the greater the thickness of the medium being fed, the longer the shadow of the leading edge of that medium in the input image. Therefore, the detection unit 162 may change the threshold according to the thickness of the medium being fed. Since the types (thicknesses) of the media placed together on the mounting stage 103 are likely to be the same, for example, the detection unit 162 estimates the thickness of the medium by the length of the shadow of the leading edge of the medium fed after the preceding medium. The detection unit 162 detects the region 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 the distance corresponding to the number of pixels in that region as a threshold for comparing it with the length of the shadow of the preceding medium. As a result, the detection unit 162 can detect the distance between media with high accuracy, regardless of the thickness of the media being fed, between the leading edge position of the preceding medium and the leading edge position of the next medium following the preceding medium.

[0162] Next, the detection unit 162 determines whether the leading edge position of the preceding medium is located downstream of a predetermined position within the nip section N in the medium transport direction A1 (step S406).

[0163] The detection unit 162 determines that the leading edge position of the preceding medium is located downstream of the predetermined position 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 downstream of the predetermined position. On the other hand, the detection unit 162 determines that the leading edge position of the preceding medium is located upstream of the predetermined position 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. In this case, the detection unit 162 determines that the leading edge position of the preceding medium is located upstream of the predetermined position 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.

[0164] Furthermore, in steps S407 and S410, the detection unit 162 determines whether the distance between media, between the leading edge position of the preceding medium and the leading edge position of the next medium following the preceding medium, is greater than or equal to a threshold (steps S407, S410).

[0165] The detection unit 162 determines that the distance between media between the leading edge of the preceding medium and the leading edge of the next medium is greater than or equal to the threshold if both the distance between media detected from the input image and the distance between media detected from the second input image are greater than or equal to the threshold. On the other hand, the detection unit 162 determines that the distance between media between the leading edge of the preceding medium and the leading edge of the next medium is less than the threshold if at least one of the distance between media detected from the input image and the distance between media detected from the second input image is less than or equal to the threshold. The detection unit 162 may also determine that the distance between media between the leading edge of the preceding medium and the leading edge of the next medium is greater than or equal to the threshold if at least one of the distance between media detected from the input image and the distance between media detected from the second input image is greater than or equal to the threshold. 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 determines that the inter-medium distance between the leading edge position of the preceding medium and the leading edge position of the next medium following the preceding medium is less than the threshold.

[0166] In this way, the detection unit 162 uses two input images captured with different light irradiation directions to detect the leading edge position of the medium and the inter-medium distance between the leading edge position of the preceding medium and the leading edge position of the next medium. This allows the detection unit 162 to detect the leading edge position of the medium and the inter-medium distance with higher accuracy. Alternatively, the detection unit 162 may detect the leading edge position of the medium and the inter-medium distance using only the second input image without using the input images.

[0167] Note that, similar to the setting process in Figure 8, steps S406 and S410-S412, or steps S407, S409, S410 and S412 may be omitted. Also, in steps S408-S409 and S411-S412, the setting unit 163 may set the pressing force by the pressing mechanism 116 in the same manner as steps S306-S307 and S309-S310 in Figure 11.

[0168] As detailed above, the media feeding device 100 can appropriately suppress the occurrence of double feeding of media even when detecting the leading edge position of the media and the distance between media using two input images generated with different light irradiation directions.

[0169] Figure 14 shows a schematic configuration of a processing circuit 260 in a media supply device according to yet another embodiment. The processing circuit 260 is used in place of the processing circuit 160 and performs media reading processing, etc., instead of the processing circuit 160. The processing circuit 260 includes a control circuit 261, a detection circuit 262, a setting circuit 263, etc. Each of these parts may be composed of an independent integrated circuit, microprocessor, firmware, etc.

[0170] The control circuit 261 is an example of a control unit and has the same functions as the control unit 161. The control circuit 261 receives operation signals from the operating device 105 or the interface device 143. The control circuit 261 also receives the first medium signal, second medium signal, and third medium signal from the first medium sensor 111, second medium sensor 117, and third medium sensor 120, respectively. Based on the received signals, the control circuit 261 controls the first motor 131, second motor 141, and third motor 142, and acquires a medium image from the second imaging device 121 and outputs it to the interface device 143.

[0171] The detection circuit 262 is an example of a detection unit and has the same functions as the detection unit 162. The detection circuit 262 receives an input image from the first imaging device 115 while controlling the light source device 114. Based on the received input image, the detection circuit 262 detects the leading edge position of the medium and the distance between the mediums, and outputs the detection result to the setting circuit 263.

[0172] The setting circuit 263 is an example of a setting unit and has the same functions as the setting unit 163. The setting circuit 263 receives detection results of the leading edge position of the medium and the distance between the mediums 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.

[0173] As detailed above, the media feeding device is capable of appropriately suppressing the occurrence of double feeding of the media, even when using the processing circuit 260.

[0174] While preferred embodiments have been described above, the embodiments are not limited thereto. For example, in a media feeding device, instead of the first to fourth electromagnetic clutches 133a to d and the first to fourth torque limiters 134a to d, a single electromagnetic clutch may be used to define the torque limit value applied to the separation roller 113. Instead of switching the first to fourth torque limiters 134a to d, the setting unit 163 controls the electromagnetic clutch to change the torque limit value applied to the separation roller 113. In this case as well, the media feeding device can appropriately suppress the occurrence of double feeding of the media.

[0175] Furthermore, the media feeding device may have a so-called U-turn path and feed and transport the media placed on the mounting table sequentially from the top, and discharge it to the discharge table. In this case, the separation roller is positioned below the feeding roller and opposite to the feeding roller. The first and second light source devices are positioned below the media transport path and irradiate light upward (towards the media transport path). The first imaging device is positioned below the media transport path and images the upper side. In this case as well, the media feeding device can appropriately suppress the occurrence of double feeding of media. [Explanation of symbols]

[0176] 100 Medium 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

1. Mounting platform and A feeding roller that sequentially feeds multiple media placed on the aforementioned mounting platform, A separation roller positioned opposite the aforementioned feeding roller, A detection unit for detecting the leading edge position of the medium at the nip portion of the feeding roller and the separating roller, It has a setting unit that sets the torque value of the separation roller or the pressing force that presses the separation roller toward the feeding roller as a characteristic value, The setting unit changes the characteristic value according to the distance between media, between the leading edge position of the preceding medium detected by the detection unit within the nip portion and the leading edge position of the next medium following the preceding medium. A media supply and delivery device characterized by the following features.

2. The characteristic value is the torque value, The separation roller is configured to rotate in the same direction as the feeding roller when a torque greater than or equal to the torque value is applied. The medium feeding device according to claim 1, wherein the setting unit sets the torque value to a first torque value when the distance between the media is greater than or equal to a threshold, and sets the torque value to a second torque value greater than the first torque value when the distance between the media is less than the threshold.

3. The medium feeding device according to claim 2, wherein the setting unit sets the torque value to a third torque value that is greater than the first torque value and less than the second torque value when the leading edge position of the preceding medium detected by the detection unit is located downstream in the medium transport direction from a predetermined position in the nip portion and the distance between the mediums is greater than or equal to the threshold value.

4. The medium feeding device according to claim 2 or 3, wherein the setting unit sets the torque value to the second torque value or a fourth torque value greater than the second torque value when the leading edge position of the preceding medium detected by the detection unit is located downstream in the medium transport direction from a predetermined position in the nip portion and the distance between the mediums is less than the threshold value.

5. The separation roller further has a pressing portion that presses it toward the feeding roller, The characteristic value is the pressing force applied by the pressing portion to press the separation roller toward the feeding roller. The medium feeding device according to claim 1 or 2, wherein the setting unit sets the pressing force to a first pressing force when the distance between the media is greater than or equal to a threshold, and sets the pressing force to a second pressing force that is less than the first pressing force when the distance between the media is less than the threshold.

6. The medium feeding device according to claim 1 or 2, wherein the detection unit detects the tip position immediately before the rotation of the feeding roller begins.

7. The system further includes an imaging unit that generates an input image capturing the leading edge position of the medium in the region that overlaps with the nip portion when viewed from a direction perpendicular to the medium transport direction. The medium feeding device according to claim 1 or 2, wherein the detection unit detects the leading edge position of the medium in the nip portion based on the input image.

8. The media feeding device according to claim 7, wherein the imaging unit is arranged downstream of the nip unit in the media transport direction.

9. The medium feeding device according to claim 8, further comprising an irradiation unit positioned upstream of the nip portion in the medium transport direction, which irradiates an area that overlaps with the nip portion when viewed from a direction perpendicular to the medium transport direction.

10. The medium feeding device according to claim 9, further comprising a second irradiation unit positioned upstream of the nip unit in the medium transport direction, which irradiates a region overlapping with the nip unit when viewed from a direction perpendicular to the medium transport direction, from a direction different from that of the irradiation unit.

11. The feed roller sequentially feeds multiple media placed on the mounting platform. The leading edge position of the medium at the nip portion of the feeding roller and the separation roller positioned opposite the feeding roller is detected. This includes setting the torque value of the separation roller or the pressing force that presses the separation roller toward the feeding roller as a characteristic value, In the above setting, the characteristic value is changed according to the distance between media, between the leading edge position of the preceding medium detected within the nip portion and the leading edge position of the next medium following the preceding medium. A media supply and delivery method characterized by the following:

12. A control program for a media feeding device having a mounting table, a feeding roller for sequentially feeding a plurality of media placed on the mounting table, and a separation roller positioned opposite the feeding roller, The leading edge position of the medium at the nip portion of the feeding roller and the separating roller is detected. The medium feeding device is instructed to set the torque value of the separation roller or the pressing force that presses the separation roller toward the feeding roller as a characteristic value. In the above setting, the characteristic value is changed according to the distance between media, between the leading edge position of the preceding medium detected within the nip portion and the leading edge position of the next medium following the preceding medium. A control program characterized by the following features.

Images