Medium feeding device

Abstract

To provide a medium feeding device capable of feeding a medium further satisfactorily while suppressing an increase in a device cost.SOLUTION: A medium feeding device includes: a feeding roller that feeds a medium; a separation roller disposed opposite the feed roller and attached to a rotating shaft to which no power is transmitted; a torque limiter provided on the rotating shaft and causes the separation roller to follow the feeding roller when a torque greater than a predetermined torque is applied; a unit that supports the rotating shaft and is provided so as to be able to swing; a pressing part that applies a pressing force to the unit to swing the unit so that the separation roller is pressed against the feed roller; and a reaction force generating part that applies a reaction force to the unit to swing the unit so that the separation roller is separated from the feed roller as the separation roller rotates.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a media feeding device. [Background technology]

[0002] 2. Description of the Related Art Generally, a medium feeding device such as a scanner feeds a plurality of media while separating them, using a feed roller that feeds the media and a separation roller that is disposed opposite the feed roller.

[0003] A document separating and feeding device is disclosed that separates and feeds documents placed on a document feed tray one by one by the action of a separating roller and a retard roller that elastically contacts the separating roller (see Patent Document 1). In this document separating and feeding device, a retard roller unit is formed by a retard roller, a retard roller shaft that concentrically holds the retard roller, and a driven transmission gear that is concentrically fixed to the retard roller shaft. A drive transmission means for transmitting drive to the retard roller is installed in the device body. The drive transmission means includes a rotating drive shaft, a drive transmission gear that meshes with the driven transmission gear to transmit the rotational drive force from the rotating drive shaft, and a pair of bracket members that are supported so as to be swingable around the axis of the drive transmission gear and have bearings that support the retard roller shaft at both axial ends.

[0004] A medium conveying device is disclosed that has a feed roller that feeds a medium, a separation roller that is disposed opposite the feed roller and separates the medium, and a motor that generates a driving force for rotating the separation roller in a direction opposite to the medium feeding direction (see Patent Document 2). This medium conveying device has a unit that includes a first gear that rotates according to the driving force generated by the motor, a second gear provided on the rotation shaft of the separation roller, and a third gear provided between the first gear and the second gear, and is supported so as to be swingable around the shaft of the first gear as the rotation shaft. The separation roller is pressed toward the feed roller by a force generated by limiting the torque that the separation roller tries to rotate in a direction opposite to the rotation direction of the feed roller by the torque limiter. The first gear rotates by the rotation of the motor in a direction that generates a force that separates the separation roller from the feed roller. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2008-260612 A [Patent Document 2] Patent Publication No. 2022-86609 Summary of the Invention [Problem to be solved by the invention]

[0006] There is a demand for medium feeding devices that can feed media well while suppressing increases in device costs.

[0007] An object of the present invention is to provide a medium feeding device that is capable of feeding a medium well while suppressing an increase in the cost of the device. [Means for solving the problem]

[0008] A medium feeding device according to one aspect of the present invention comprises a feed roller for feeding a medium, a separation roller arranged opposite the feed roller and mounted on a rotating shaft to which no power is transmitted, a torque limiter mounted on the rotating shaft and causing the separation roller to follow the feed roller when a torque greater than a predetermined torque is applied, a unit supporting the rotating shaft and arranged to be swingable, a pressing section that applies a pressing force to the unit to swing the unit so that the separation roller is pressed towards the feed roller, and a reaction force generating section that applies a reaction force to the unit to swing the unit so that the separation roller is moved away from the feed roller as the separation roller rotates. Effect of the Invention

[0009] According to the present invention, the medium feeding device is capable of feeding the medium more effectively while suppressing an increase in the cost of the device. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view showing a medium feeding device 100. [Diagram 2] 2 is a diagram for explaining a transport path inside the medium feeding device 100. FIG. [Diagram 3] 2 is a schematic diagram for explaining a separation roller unit 121. FIG. [Figure 4] 1 is a block diagram showing a schematic configuration of a medium feeding device 100. FIG. [Diagram 5] FIG. 2 is a diagram showing a schematic configuration of a storage device 140 and a processing circuit 150. [Figure 6] 10 is a flowchart illustrating an example of the operation of a medium reading process. [Figure 7] 13 is a schematic diagram for explaining another separation roller unit 221. FIG. [Figure 8] 13 is a schematic diagram for explaining another separation roller unit 321. FIG. [Figure 9] FIG. 13 is a diagram showing a schematic configuration of another processing circuit 450. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, a medium feeding device, a medium feeding method, and a control program according to one aspect of the present invention will be described with reference to the drawings. However, it should be noted that the technical scope of the present invention is not limited to the embodiments, but extends to the inventions described in the claims and their equivalents.

[0012] 1 is a perspective view showing a medium feeding device 100 configured as an image scanner. Medium feeding device 100 conveys a medium, which is an original document, and captures an image. The medium is paper, cardboard, card, or the like. Medium feeding device 100 may be a facsimile, a copier, a multifunction printer (MFP, Multifunction Peripheral), or the like. Note that the medium being conveyed may not be an original document, but may be a print target, or the like, and medium feeding device 100 may be a printer, or the like.

[0013] 1, arrow A1 indicates the substantially vertical direction (height direction), arrow A2 indicates the medium transport direction, arrow A3 indicates the medium discharge direction, and arrow A4 indicates the width direction perpendicular to the medium transport direction A2 or the medium discharge direction A3. In the following, upstream refers to the upstream of the medium transport direction A2 or the medium discharge direction A3, and downstream refers to the downstream of the medium transport direction A2 or the medium discharge direction A3.

[0014] The medium feeding device 100 includes a first housing 101, a second housing 102, a placement table 103, a discharge table 104, an operation device 105, a display device 106, and the like.

[0015] The second housing 102 is disposed inside the first housing 101 and rotatably engaged with the first housing 101 by a hinge so as to be openable and closable when a medium is jammed or when the inside of the medium feeding device 100 is cleaned.

[0016] The placement table 103 engages with the first housing 101 so as to place the medium to be transported thereon. The placement table 103 is provided on the side surface of the first housing 101 on the medium supply side so as to be movable in the height direction A1, i.e., so as to be able to rise and fall. The placement table 103 is disposed at the bottom end position so that the medium can be easily placed on it when the medium is not being transported, and when the medium is being transported, the uppermost medium placed on the placement table 103 rises to a position where it comes into contact with a pick roller, which will be described later.

[0017] The discharge stage 104 is formed on the second housing 102. The discharge stage 104 places the media discharged from the discharge ports of the first housing 101 and the second housing 102 thereon.

[0018] The operation device 105 has an input device such as a button and an interface circuit for acquiring a signal from the input device, accepts an input operation by a user, and outputs an operation signal according to the user's input operation. The display device 106 has a display including a liquid crystal, an organic EL (Electro-Luminescence), or the like, and an interface circuit for outputting image data to the display, and displays the image data on the display. The display device 106 may be a liquid crystal display with a touch panel function. In that case, the operation device 105 has an interface circuit for acquiring an input signal from the touch panel.

[0019] FIG. 2 is a diagram for explaining the transport path inside the medium feeding device 100. As shown in FIG.

[0020] The transport path inside medium feeding device 100 includes a medium sensor 111, a pick roller 112, a feeding roller 113, a separation roller 114, a torque limiter 115, first to sixth transport rollers 116a-f, first to sixth driven rollers 117a-f, an imaging device 118, and the like.

[0021] The number of each of the pick roller 112, the feed roller 113, the separation roller 114, the first to sixth conveying rollers 116a-f, and / or the first to sixth driven rollers 117a-f is not limited to one, and may be more than one. In this case, the multiple feed rollers 113, the separation roller 114, the first to sixth conveying rollers 116a-f, and / or the first to sixth driven rollers 117a-f are arranged at intervals in the width direction A4.

[0022] The second housing 102 is disposed opposite the first housing 101 across the medium transport path. The surface of the first housing 101 facing the second housing 102 forms a first guide 101a of the medium transport path, and the surface of the second housing 102 facing the first housing 101 forms a second guide 102a of the medium transport path.

[0023] The media sensor 111 is disposed on the mounting table 103, that is, upstream of the feed roller 113 and the separation roller 114, and detects the state of the medium on the mounting table 103. The media sensor 111 determines whether or not a medium is placed on the mounting table 103 by using a contact detection sensor that passes a predetermined current when the medium is in contact or not in contact. The media sensor 111 generates and outputs a first media signal whose signal value changes depending on whether or not the medium is placed on the mounting table 103. Note that the media 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 media sensor 111.

[0024] Pick roller 112 is disposed in second housing 102, upstream of feed roller 113 and separation roller 114 in media transport direction A2. Pick roller 112 is disposed above mounting table 103, and feeds media placed on mounting table 103. Pick roller 112 comes into contact with the uppermost medium among the media placed on mounting table 103, which has been raised to approximately the same height as the media transport path, and feeds the medium downstream.

[0025] The feed roller 113 is provided in the second housing 102 downstream of the pick roller 112, and feeds the medium placed on the placement table 103 and fed by the pick roller 112 further downstream. The separation roller 114 is provided in the first housing 101 facing the feed roller 113. The separation roller 114 is provided on a shaft 114a, which is a rotating shaft to which no power is transmitted. The separation roller 114 is a so-called brake roller, and is provided so as to be stoppable by a torque limiter 115. The feed roller 113 and the separation roller 114 perform a media separation operation, separate the media, and feed the media one by one. The feed roller 113 is provided above the separation roller 114, and the medium feeding device 100 feeds the media by a so-called top-take method.

[0026] In this way, separation roller 114 separates the medium using torque limiter 115 without using driving force from a drive source (motor). Because separation roller 114 is not driven by power, medium feeding device 100 does not have a motor for driving separation roller 114, and therefore it is possible to reduce the cost, size, and weight of the device. In addition, medium feeding device 100 does not have a transmission mechanism such as gears, pulleys, rollers, etc. that transmit the driving force from the motor to separation roller 114, and therefore it is possible to reduce the cost, size, and weight of the device.

[0027] Torque limiter 115 is provided on shaft 114a, which is the rotation axis of separation roller 114, and controls the load applied to separation roller 114. Since there is no gear train between torque limiter 115 and separation roller 114, fluctuations in the separation force applied to separation roller 114 due to manufacturing errors of individual parts and the like are suppressed. Therefore, medium feeding device 100 can separate the medium with high accuracy regardless of manufacturing errors of individual parts.

[0028] The first to sixth conveying rollers 116a-f and the first to sixth driven rollers 117a-f are arranged facing each other downstream of the feed roller 113 and the separation roller 114 in the medium conveying direction A2. The first to sixth conveying rollers 116a-f and the first to sixth driven rollers 117a-f convey the medium fed by the feed roller 113 and the separation roller 114 downstream. The sixth conveying roller 116f and the sixth driven roller 117f discharge the medium to the discharge tray 104.

[0029] The imaging device 118 is disposed downstream of the first and second transport rollers 116a-b in the medium transport direction A2, and captures images of the medium transported by the first and second transport rollers 116a-b and the first and second driven rollers 117a-b. The imaging device 118 includes a first imaging device 118a and a second imaging device 118b disposed opposite each other with the medium transport path in between. The first imaging device 118a is provided in the second housing 102, and the second imaging device 118b is provided in the first housing 101.

[0030] The first imaging device 118a has a line sensor using a CIS (Contact Image Sensor) of a life-size optical system type having imaging elements using CMOS (Complementary Metal Oxide Semiconductor) linearly arranged in the main scanning direction. The first imaging device 118a also has a lens that forms an image on the imaging elements, and an A / D converter that amplifies and analog-to-digital (A / D) converts the electrical signal output from the imaging elements. The first imaging device 118a captures an image of the surface of the medium being transported, generates an input image, and outputs it.

[0031] Similarly, the second imaging device 118b has a line sensor using a CIS of a life-size optical system type having CMOS imaging elements arranged in a line in the main scanning direction. The second imaging device 118b also has a lens that forms an image on the imaging element, and an A / D converter that amplifies and analog-to-digital (A / D) converts the electrical signal output from the imaging element. The second imaging device 118b captures the back side of the medium being transported to generate an input image and output it.

[0032] The medium feeding device 100 may have only one of the first imaging device 118a and the second imaging device 118b arranged to read only one side of the medium. Also, instead of a CIS line sensor of an equal magnification optical system type having a CMOS imaging element, a CIS line sensor of an equal magnification optical system type having a CCD (Charge Coupled Device) imaging element may be used. Also, a reduction optical system type line sensor having a CMOS or CCD imaging element may be used.

[0033] The medium placed on the placement table 103 is transported between the first guide 101a and the second guide 102a in the medium transport direction A2 by the rotation of the pick roller 112 and the feed roller 113 in the medium feed directions A5 and A6, respectively. The separation roller 114 stops, restricting the feeding of media other than the separated medium (to prevent double feeding).

[0034] The medium is guided by the first guide 101a and the second guide 102a and sent to the imaging position of the imaging device 118 by the rotation of the first and second transport rollers 116a-b in the directions of arrows A7-8, and is imaged by the imaging device 118. Furthermore, the medium is discharged onto the discharge table 104 by the rotation of the third to sixth transport rollers 116c-f in the directions of arrows A9-12, respectively.

[0035] FIG. 3 is a schematic diagram for explaining the separation roller unit 121. As shown in FIG.

[0036] As shown in FIG. 3, the medium feeding device 100 further includes a separation roller unit 121, a pressing portion 122, a first transmission portion 123, a locking portion 124, a second transmission portion 125, and the like.

[0037] The separation roller unit 121 is an example of a unit. A shaft 114a, which is a rotation axis of the separation roller 114, is attached to the upstream end of the separation roller unit 121 in the medium transport direction A2, and the separation roller unit 121 supports the shaft 114a. The separation roller unit 121 is provided so as to be swingable about a swing shaft 121a provided at the downstream end of the separation roller unit 121 in the medium transport direction A2. As a result, the separation roller 114 attached to the upstream end of the separation roller unit 121 in the medium transport direction A2 is provided so as to be movable in the height direction A1, that is, toward the feed roller 113 and away from the feed roller 113.

[0038] The pressing portion 122 is an elastic member such as a torsion coil spring. The pressing portion 122 is disposed below the separation roller unit 121 and generates a pressing force in the upward direction A21. One end (one arm) of the pressing portion 122 is fixed to a frame in the first housing 101, and the other end (the other arm) of the pressing portion 122 is attached to the separation roller unit 121. As a result, the pressing portion 122 presses the separation roller unit 121 upward. That is, the pressing portion 122 applies a pressing force to the separation roller unit 121 to swing the separation roller unit 121 so that the separation roller 114 is pressed toward the feed roller 113. The pressing portion 122 may be a compression coil spring, a leaf spring, rubber, or the like. By using an elastic member as the pressing portion 122, the medium feeding device 100 can apply a pressing force to the separation roller 114 at a low cost and stably.

[0039] The first transmission part 123 is a gear. The first transmission part 123 is provided on the shaft 114a of the separation roller 114 attached to the upstream end of the separation roller unit 121 so as to rotate in conjunction with the rotation of the shaft 114a. The first transmission part 123 transmits the rotational force of the separation roller 114 in the medium feeding direction A22, in which the separation roller 114 is driven by the feeding roller 113, to the locking part 124 via the second transmission part 125.

[0040] The locking portion 124 is a gear and is fixed to a swing shaft 121a of the separation roller unit 121 provided at the end of the separation roller unit 121 on the downstream side.

[0041] The second transmission part 125 is a cam. The second transmission part 125 is provided between the first transmission part 123 and the locking part 124. The second transmission part 125 is attached to the separation roller unit 121 so as to be rotatable about a rotation shaft 121b arranged between the first transmission part 123 and the locking part 124 in the medium conveying direction A2. The second transmission part 125 has a first arm 125a extending toward the upstream side in the medium conveying direction A2 and a second arm 125b extending toward the downstream side in the medium conveying direction A2. A first tooth part 125c that engages with the first transmission part 123 is provided at the upstream end of the first arm 125a. A second tooth part 125d that engages with the locking part 124 is provided at the downstream end of the second arm 125b. In the medium transport direction A2, the first arm 125a engaging with the first transmission part 123 is longer than the second arm 125b engaging with the locking part 124. The second transmission part 125 transmits the rotational force transmitted from the first transmission part 123 to the locking part 124 in the direction in which the separation roller 114 follows the feed roller 113.

[0042] The second transmission part 125 is provided so as to extend along the medium conveying direction A2, thereby reducing the size of the second transmission part 125 in the height direction A1. Because the size of the second transmission part 125 in the height direction A1 is reduced, the designer of the medium feeding device 100 can design the medium conveying path while using a single member as the second transmission part 125, without worrying about the influence of the second transmission part 125 protruding into the medium conveying path, etc. Therefore, the medium feeding device 100 can improve the freedom of design while suppressing an increase in the device cost.

[0043] The first transmission portion 123, the locking portion 124, and the second transmission portion 125 are an example of a reaction force generating portion.

[0044] As described above, the torque limiter 115 is provided on the shaft 114a which is the rotation axis of the separation roller 114. That is, the torque limiter 115 is provided between the separation roller 114 and the shaft 114a. The first transmission part 123 which rotates in conjunction with the shaft 114a is connected to the fixed locking part 124 via the second transmission part 125, thereby preventing the shaft 114a from rotating.

[0045] The limit value of the torque limiter 115 is set to a value such that when there are multiple media between the feed roller 113 and the separation roller 114, the rotational force is transmitted between the separation roller 114 and the shaft 114a, and when there is only one medium between the feed roller 113 and the separation roller 114, the rotational force is interrupted between the separation roller 114 and the shaft 114a. As a result, the torque limiter 115 stops the separation roller 114 when a torque equal to or less than the limit value is applied, and makes the separation roller 114 follow the feed roller 113 when a torque greater than the limit value is applied. The limit value of the torque limiter 115 is an example of a predetermined torque. That is, when multiple media are conveyed, the separation roller 114 stops and separates the medium in contact with the feed roller 113 from the other media to prevent double feeding. On the other hand, when only one medium is conveyed, the separation roller 114 rotates following the feed roller 113.

[0046] The following describes the forces applied to the separation roller 114. The separation roller 114 is applied with a first force F1, a second force F2, and a third force F3.

[0047] The first force F1 is a force due to a pressing force from the pressing unit 122. As described above, the pressing unit 122 applies a pressing force in the upward direction A21 to the separation roller unit 121. This applies a rocking force in the upward direction A23 to the entire separation roller unit 121, and the first force F1 toward the feed roller 113 is applied to the separation roller 114. The first force F1 is a static force determined according to the spring constant of the pressing unit 122, and is constantly applied to the separation roller 114 regardless of whether the medium is being fed or not.

[0048] The second force F2 is a force due to the rotation moment of the separation roller unit 121. When the medium M is fed by the feed roller 113, the rotation force of the feed roller 113 in the medium feeding direction A6 is transmitted to the separation roller 114 via the medium M, and the separation roller 114 is given a rotation force in the medium feeding direction A22. As a result, a rotation moment toward the same direction A23 as the medium feeding direction A22 is given to the entire separation roller unit 121, and the second force F2 toward the feed roller 113 side is given to the separation roller 114. That is, the second force F2 is a dynamic force due to the rotation moment applied to the swing shaft 121a of the separation roller unit 121 according to the torque applied to the torque limiter 115, and is applied so as to make the separation roller 114 bite into the feed roller 113 side. The second force F2 is applied to the separation roller 114 only during feeding of the medium.

[0049] The second force F2 changes depending on the positional relationship between the nip position between the feed roller 113 and the separation roller 114 and the swing fulcrum of the separation roller 114. The second force F2 is calculated by the following formula (1). F2 = {(T / R) × L1} / L2 (1) Here, T is the limit value of the torque limiter 115. R is the radius of the separation roller 114. L1 is the distance between the nip position of the feed roller 113 and the separation roller 114 in a direction perpendicular to the nip surface of the feed roller 113 and the separation roller 114, and the oscillation center of the separation roller unit 121 (the position of the locking portion 124). L2 is the distance between the nip position of the feed roller 113 and the separation roller 114 in a direction parallel to the nip surface of the feed roller 113 and the separation roller 114, and the oscillation center of the separation roller unit 121 (the position of the locking portion 124).

[0050] The third force F3 is a force due to a reaction force from the locking portion 124. As described above, when the medium M is fed by the feed roller 113, the rotational force of the feed roller 113 in the medium feeding direction A6 is transmitted to the separation roller 114 via the medium M, and the separation roller 114 is given a rotational force in the medium feeding direction A22. Due to this rotational force, a rotational force in the clockwise direction A24 in FIG. 3 is given to the first arm 125a of the second transmission portion 125 engaged with the first transmission portion 123 which rotates in conjunction with the shaft 114a of the separation roller 114. Due to this rotational force, the second arm 125b of the second transmission portion 125 gives the locking portion 124 a rotational force directed upward along a tangent line where the locking portion 124 and the second arm 125b meet.

[0051] As described above, since the locking portion 124 is fixed, the second arm 125b receives a reaction force from the locking portion 124 in the downward direction A25 along the tangent line where the locking portion 124 and the second arm 125b meet. This reaction force applies a swinging force in the downward direction A26 to the entire separation roller unit 121, and a third force F3 in a direction away from the feed roller 113 is applied to the separation roller 114. That is, the third force F3 is a dynamic force generated according to the torque applied to the torque limiter 115, and is applied so that the separation roller 114 moves away from the feed roller 113. The third force F3 is applied to the separation roller 114 only while the medium is being fed.

[0052] The third force F3 changes according to the reduction ratio between the first transmission part 123 and the locking part 124 via the second transmission part 125, that is, the ratio between the magnitude of the torque applied to the first transmission part 123 and the magnitude of the torque applied to the locking part 124. The third force F3 is calculated by the following formula (2). F3=(T / G) / L2 (2) Here, G is the reduction ratio between the first transmission part 123 and the locking part 124 via the second transmission part 125.

[0053] The reduction ratio G is calculated by the following formula (3), for example, when the tooth modules of the first transmission part 123, the first arm 125a, the second arm 125b, and the locking part 124 are the same. G = (R1 / R2) × (R3 / R4) (3) Here, R1 is the rotation radius of first transmission part 123, R2 is the rotation radius of first arm 125a, R3 is the rotation radius of second arm 125b, and R4 is the rotation radius of locking part 124. That is, the third force F3 increases as the rotation radius R2 of first arm 125a and the rotation radius R4 of locking part 124 increase, and increases as the rotation radius R1 of first transmission part 123 and the rotation radius R3 of second arm 125b decrease.

[0054] In this manner, the second transmission unit 125 transmits the rotational force transmitted from the first transmission unit 123 in the direction in which the separation roller 114 follows the feed roller 113 to the locking unit 124. In particular, the second transmission unit 125 transmits the rotational force to the locking unit 124 so that the locking unit 124 generates a reaction force that rocks the separation roller unit 121 so that the separation roller 114 is separated from the feed roller 113. In this manner, the first transmission unit 123, the locking unit 124, and the second transmission unit 125 impart to the separation roller unit 121 a reaction force that rocks the separation roller unit 121 so that the separation roller 114 is separated from the feed roller 113 as the separation roller 114 rotates.

[0055] In order for the feed roller 113 and the separation roller 114 to properly separate the media, the feed roller 113 and the separation roller 114 need to pinch the media with a specified force. If the force with which the feed roller 113 and the separation roller 114 pinch the media is too large, there is a possibility that double feeding of media will occur. Therefore, the force pressing the separation roller 114 towards the feed roller 113 and the force moving the separation roller 114 away from the feed roller 113 need to be properly balanced.

[0056] As described above, the force pressing the separation roller 114 towards the feed roller 113 includes the first force F1 due to the pressing force from the pressing unit 122 and the second force F2 due to the rotational moment of the separation roller unit 121. The first force F1 is a static force due to the pressing force of the pressing unit 122, and does not fluctuate when the medium is fed. On the other hand, the second force F2 is a dynamic force generated in association with the feeding of the medium, and fluctuates slightly due to slight vibrations caused by unevenness formed on the surfaces (rubber) of the feed roller 113 and the separation roller 114, or the engagement timing of the members inside the torque limiter 115, etc.

[0057] When the second force F2 is large relative to the first force F1, the degree of fluctuation of the force applied to the medium during feeding increases. When the force applied to the medium increases, the force with which the feed roller 113 and the separation roller 114 pinch the medium becomes too large, and there is a possibility that double feeding of the medium occurs. Also, when the force applied to the medium decreases, the medium that is not the object of feeding advances between the feed roller 113 and the separation roller 114, and there is a possibility that double feeding of the medium occurs. Therefore, in order to stabilize the force applied to the medium and suppress the occurrence of double feeding of the medium, it is desirable to increase the first force F1 and decrease the second force F2. However, since the second force F2 depends on the torque applied to the torque limiter 115, which should be adjusted according to the characteristics of the medium to be fed, it is difficult to decrease the second force F2 in order to change the force pressing the separation roller 114 toward the feed roller 113. On the other hand, if the first force F1 is simply increased, the force with which the feed roller 113 and the separation roller 114 pinch the medium becomes too large, and double feeding of the medium is likely to occur.

[0058] By fixing the locking portion 124, the medium feeding device 100 applies a third force F3 caused by the reaction force from the locking portion 124 to the separation roller 114 as a force that separates the separation roller 114 from the feed roller 113. This allows the medium feeding device 100 to increase the first force F1 caused by the pressing force from the pressing portion 122 by the amount of the third force F3 caused by the reaction force from the locking portion 124 that is applied to the separation roller 114. Therefore, the medium feeding device 100 can increase the first force F1, which does not fluctuate when feeding the medium, relative to the second force F2, which fluctuates when feeding the medium, and can feed the medium stably.

[0059] As described above, the third force F3 also depends on the torque applied to the torque limiter 115, similar to the second force F2. However, the third force F3 can be adjusted by adjusting the reduction ratio between the first transmission unit 123 and the locking unit 124 via the second transmission unit 125, that is, by adjusting the length of the first arm 125a and the length of the second arm 125b. Therefore, the medium feeding device 100 can increase the third force F3 while appropriately adjusting the force applied to the separation roller 114 by adjusting the reduction ratio by the second transmission unit 125. This allows the medium feeding device 100 to further increase the first force F1 and stably feed the medium.

[0060] In particular, by making the length of first arm 125a greater than the length of second arm 125b, medium feeding device 100 can increase the magnitude of the torque applied to locking portion 124 relative to the magnitude of the torque applied to first transmission portion 123, and can further increase third force F3. This allows medium feeding device 100 to further increase first force F1, and can stably feed the medium.

[0061] For example, the rotation moment of the separation roller unit 121 is reduced by moving the nip position of the feed roller 113 and the separation roller 114 away from the swing center of the separation roller unit 121 in a direction parallel to the nip surface of the feed roller 113 and the separation roller 114. Also, the rotation moment of the separation roller unit 121 is reduced by moving the nip position of the feed roller 113 and the separation roller 114 closer to the swing center of the separation roller unit 121 in a direction perpendicular to the nip surface of the feed roller 113 and the separation roller 114. Therefore, the second force F2 can be reduced by these. However, if the shape of the separation roller unit 121 is limited, the shape of the medium transport path is limited, making it difficult to appropriately design the medium transport path. The medium feeding device 100 can stably feed the medium while suppressing restrictions on the degree of freedom of design by fixing the locking portion 124.

[0062] FIG. 4 is a block diagram showing a schematic configuration of the medium feeding device 100. As shown in FIG.

[0063] In addition to the above-mentioned components, the medium feeding device 100 further includes a motor 131, an interface device 132, a storage device 140, a processing circuit 150, and the like.

[0064] The motor 131 includes one or more motors. The motor 131 rotates the pick roller 112, the feed roller 113, and the first to sixth transport rollers 116a-f in response to a control signal from the processing circuit 150 to feed and transport the medium. The separation roller 114 is not rotated by the driving force from the motor. The first to sixth driven rollers 117a-f may be provided so as to rotate according to the driving force of the motor 131, rather than being driven by the first to sixth transport rollers 116a-f. The motor 131 also moves the placement table 103 in response to a control signal from the processing circuit 150.

[0065] The interface device 132 has an interface circuit conforming to a serial bus such as USB, and is electrically connected to an information processing device (not shown, for example, a personal computer, a mobile information terminal, etc.) to transmit and receive input images and various information. Also, instead of the interface device 132, a communication unit having an antenna for transmitting and receiving wireless signals and a wireless communication interface circuit for transmitting and receiving signals through a wireless communication line in accordance with a predetermined communication protocol may be used. The predetermined communication protocol is, for example, a wireless LAN (Local Area Network). The communication unit may have a wired communication interface circuit for transmitting and receiving signals through a wired communication line in accordance with a communication protocol such as a wired LAN.

[0066] The storage device 140 includes a memory device such as a random access memory (RAM) or a read only memory (ROM), a fixed disk device such as a hard disk, or a portable storage device such as a flexible disk or an optical disk. The storage device 140 also stores computer programs, databases, tables, and the like used for various processes of the medium feeding device 100. The computer programs may be installed in the storage device 140 from a computer-readable portable recording medium using a known setup program or the like. The portable recording medium is, for example, a compact disc read only memory (CD-ROM) or a digital versatile disc read only memory (DVD-ROM). The computer programs may be distributed from a server or the like and installed in the storage device 140.

[0067] The processing circuit 150 operates based on a program previously stored in the storage device 140. The processing circuit is, for example, a CPU (Central Processing Unit). The processing circuit 150 may be, for example, a DSP (digital signal processor), an LSI (large scale integration), an ASIC (Application Specific Integrated Circuit), or an FPGA (Field-Programmable Gate Array).

[0068] The processing circuit 150 is connected to the operation device 105, the display device 106, the medium sensor 111, the imaging device 118, the motor 131, the interface device 132, the storage device 140, etc., and controls each of these components. The processing circuit 150 performs drive control of each motor, imaging control of the imaging device 118, etc., based on each signal received from each sensor. The processing circuit 150 acquires an input image from the imaging device 118, and transmits it to the information processing device via the interface device 132.

[0069] FIG. 5 is a diagram showing a schematic configuration of the storage device 140 and the processing circuit 150. As shown in FIG.

[0070] 5, the storage device 140 stores a control program 141, an image acquisition program 142, and the like. Each of these programs is a functional module implemented by software that runs on a processor. The processing circuitry 150 reads each program stored in the storage device 140 and operates according to the read program. In this way, the processing circuitry 150 functions as a control unit 151 and an image acquisition unit 152.

[0071] FIG. 6 is a flowchart showing an example of the operation of the medium feeding device 100 in a medium reading process.

[0072] An example of the operation of the medium reading process of the medium feeding device 100 will be described below with reference to the flowchart shown in Fig. 6. The flow of the operation described below is executed mainly by the processing circuit 150 in cooperation with each element of the medium feeding device 100 based on a program stored in advance in the storage device 140.

[0073] First, the control unit 151 waits until a user inputs an instruction to read a medium using the operation device 105 or an information processing device, and an operation signal instructing the user to read a medium is received from the operation device 105 or the interface device 132 (step S101).

[0074] Next, control unit 151 acquires a medium signal from medium sensor 111, and determines whether or not a medium is placed on mounting table 103 based on the acquired medium signal (step S102). If no medium is placed on mounting table 103, control unit 151 ends the series of steps.

[0075] On the other hand, if a medium is placed on the mounting table 103, the control unit 151 drives the motor 131 to raise the mounting table 103 to a position where the medium can be fed, and rotates each roller to feed and transport the medium (step S103).

[0076] Next, the control unit 151 causes the imaging device 118 to capture an image of the medium, acquires an input image from the imaging device 118, and outputs the acquired input image by transmitting it to the information processing device via the interface device 132 (step S104).

[0077] Next, control unit 151 determines whether or not a medium remains on mounting table 103 based on the medium signal received from medium sensor 111 (step S105). If a medium remains on mounting table 103, control unit 151 returns the process to step S104, and repeats the processes of steps S104 to S105.

[0078] On the other hand, if there are no media remaining on the mounting table 103, the control unit 151 controls the motor 131 to stop each roller (step S106), and ends the series of steps.

[0079] As described above in detail, the medium feeding device 100 separates the medium by the separation roller 114 provided on a rotating shaft to which no power is transmitted. The medium feeding device 100 also applies a reaction force to the separation roller unit 121 that supports the separation roller 114 so that the separation roller 114 is separated from the feeding roller 113 as the separation roller 114 rotates. This enables the medium feeding device 100 to better feed the medium while suppressing increases in the device cost, device size, and device weight.

[0080] FIG. 7 is a schematic diagram for explaining a separation roller unit 221 of a medium feeding device according to another embodiment.

[0081] The medium feeding device according to this embodiment has a separation roller unit 221 and a second transmission part 225 instead of the separation roller unit 121 and the second transmission part 125.

[0082] The separation roller unit 221 has the same structure and function as the separation roller 114, and is provided so as to be swingable about a swing shaft 221a provided at the end on the downstream side in the medium transport direction A2. However, the separation roller unit 221 is provided with a second transmission unit 225 instead of the second transmission unit 125.

[0083] The second transmission unit 225 is a gear. The second transmission unit 225 is provided between the first transmission unit 123 and the locking unit 124. The second transmission unit 225 is attached to the separation roller unit 221 so as to be rotatable about a rotation shaft 121b disposed between the first transmission unit 123 and the locking unit 124 in the medium conveying direction A2. The second transmission unit 225 is a two-stage gear having a first gear portion 225a and a second gear portion 225b. The first gear portion 225a is provided with a first tooth portion 225c that engages with the first transmission unit 123. The second gear portion 225b is provided with a second tooth portion 225d that engages with the locking unit 124. The rotation radius of the first gear portion 225a engaging with the first transmission portion 123 is larger than the rotation radius of the second gear portion 225b engaging with the locking portion 124, and the number of teeth of the first gear portion 225a is larger than the number of teeth of the second gear portion 225b. That is, the second transmission portion 225 functions as a reduction gear that changes the rotation force from the first transmission portion 123 and transmits it to the locking portion 124. The second transmission portion 225 transmits the rotation force transmitted from the first transmission portion 123 in the direction in which the separation roller 114 follows the feed roller 113 to the locking portion 124 via the first gear portion 225a and the second gear portion 225b.

[0084] By using a general-purpose two-stage gear as the second transmission part 225, the medium feeding device can suppress an increase in device costs.

[0085] In the medium feeding device according to this embodiment, similarly to the medium feeding device 100, the separation roller 114 is applied with a first force F1, a second force F2, and a third force F3.

[0086] The third force F3 is a force due to a reaction force from the locking portion 124, similar to the third force F3 in the medium feeding device 100. A rotational force in the clockwise direction A24 in FIG. 7 is applied to the first gear portion 225a of the second transmission portion 225 by the rotational force of the separation roller 114 in the medium feeding direction A22. Due to this rotational force, the second gear portion 225b of the second transmission portion 225 applies a rotational force in the upward direction along the tangent line where the locking portion 124 and the second gear portion 225b are in contact to the locking portion 124. The locking portion 124 is fixed, and the second gear portion 225b receives a reaction force from the locking portion 124 in the downward direction A25 along the tangent line where the locking portion 124 and the second gear portion 225b are in contact. Due to this reaction force, a swinging force in the downward direction A26 is applied to the entire separation roller unit 221, and a third force F3 in a direction away from the feed roller 113 is applied to the separation roller 114.

[0087] The reduction ratio G between the first transmission part 123 and the locking part 124 via the second transmission part 225 is calculated by the following equation (4), for example, when the tooth modules of the first transmission part 123, the first gear part 225a, the second gear part 225b, and the locking part 124 are the same. G=(R1 / R2)×(R3 / R4)=(N1 / N2)×(N3 / N4) (4) Here, R1 is the rotation radius of the first transmission part 123, R2 is the rotation radius of the first gear part 225a, R3 is the rotation radius of the second gear part 225b, and R4 is the rotation radius of the locking part 124. Furthermore, N1 is the number of teeth of the first transmission part 123, N2 is the number of teeth of the first gear part 225a, N3 is the number of teeth of the second gear part 225b, and N4 is the number of teeth of the locking part 124. That is, the third force F3 becomes larger as the rotation radius R2 of the first gear part 225a and the rotation radius R4 of the locking part 124 become larger, and becomes larger as the rotation radius R1 of the first transmission part 123 and the rotation radius R3 of the second gear part 225b become smaller. The third force F3 increases as the number of teeth N2 of the first gear portion 225a and the number of teeth N4 of the locking portion 124 increase, and increases as the number of teeth N1 of the first transmission portion 123 and the number of teeth N3 of the second gear portion 225b decrease.

[0088] The second transmission unit 225, like the second transmission unit 125, transmits the rotational force transmitted from the first transmission unit 123 to the locking unit 124 in the direction in which the separation roller 114 follows the feed roller 113. In particular, the second transmission unit 225 transmits the rotational force to the locking unit 124 so that the locking unit 124 generates a reaction force that rocks the separation roller unit 221 so that the separation roller 114 is separated from the feed roller 113 against the rotational force. In this way, the first transmission unit 123, the locking unit 124, and the second transmission unit 225 impart to the separation roller unit 221 a reaction force that rocks the separation roller unit 221 so that the separation roller 114 is separated from the feed roller 113 as the separation roller 114 rotates.

[0089] As described above in detail, even when using the separation roller unit 221 and the second transmission unit 225, the medium feeding device is able to feed the medium better while suppressing increases in device costs, device size, and device weight.

[0090] FIG. 8 is a schematic diagram for explaining a separation roller unit 321 of a medium feeding device according to yet another embodiment.

[0091] The medium feeding device according to this embodiment has a separation roller unit 321, a first transmission part 323, a locking part 324 and a second transmission part 325 instead of the separation roller unit 121, the first transmission part 123, the locking part 124 and the second transmission part 125.

[0092] The separation roller unit 321 has the same structure and function as the separation roller 114. However, in place of the first transmission part 123, the locking part 124, and the second transmission part 125, the separation roller unit 321 is provided with a first transmission part 323, a locking part 324, and a second transmission part 325.

[0093] The first transmission part 323 is a pulley. The first transmission part 323 is provided on the shaft 114a of the separation roller 114 so as to rotate in conjunction with the rotation of the shaft 114a. The first transmission part 323 transmits the rotational force of the separation roller 114 in the medium feeding direction A22, in which the separation roller 114 is driven by the feeding roller 113, to the locking part 324 via the second transmission part 325.

[0094] The locking portion 324 is a pulley. The locking portion 324 is fixed to the swing shaft 321a of the separation roller unit 321. The rotation radius of the locking portion 324 is larger than the rotation radius of the first transmission portion 323, and the number of teeth of the locking portion 324 is larger than the number of teeth of the first transmission portion 323.

[0095] The second transmission part 325 is a belt. The second transmission part 325 is suspended between the first transmission part 323 and the locking part 324 so as to engage with the first transmission part 323 and the locking part 324. The second transmission part 325 transmits the rotational force transmitted from the first transmission part 323 to the locking part 324 in the direction in which the separation roller 114 follows the feed roller 113.

[0096] By using general-purpose pulleys and belts as the first transmission part 323, the locking part 324, and the second transmission part 325, the medium feeding device can suppress an increase in device costs.

[0097] In the medium feeding device according to this embodiment, similarly to the medium feeding device 100, the separation roller 114 is applied with a first force F1, a second force F2, and a third force F3.

[0098] The third force F3 is a force due to a reaction force from the locking portion 324, similar to the third force F3 in the medium feeding device 100. A rotational force in the counterclockwise direction A34 in FIG. 8 is applied to the second transmission portion 325 by the rotational force of the separation roller 114 in the medium feeding direction A22. This rotational force causes the second transmission portion 325 to apply a rotational force in the counterclockwise direction A34 to the locking portion 324. The locking portion 324 is fixed, and the second transmission portion 325 receives a reaction force in the clockwise direction A35 from the locking portion 324. This reaction force applies a force (rotational moment) in the downward direction A26 to the entire separation roller unit 321, and the third force F3 in a direction away from the feed roller 113 is applied to the separation roller 114.

[0099] The reduction ratio G between the first transmission part 323 and the locking part 324 via the second transmission part 325 is calculated by the following formula (5). G=R1 / R4=N1 / N4 (5) Here, R1 is the rotation radius of first transmission part 323, and R4 is the rotation radius of locking part 324. Furthermore, N1 is the number of teeth of first transmission part 323, and N4 is the number of teeth of locking part 124. That is, the third force F3 increases as the rotation radius R4 of locking part 124 increases, and increases as the rotation radius R1 of first transmission part 123 decreases. Furthermore, the third force F3 increases as the number of teeth N4 of locking part 124 increases, and increases as the number of teeth N1 of first transmission part 123 decreases.

[0100] The second transmission unit 325, like the second transmission units 125 and 225, transmits the rotational force transmitted from the first transmission unit 323 in the direction in which the separation roller 114 follows the feed roller 113 to the locking unit 324. In particular, the second transmission unit 325 transmits the rotational force to the locking unit 324 so that the locking unit 324 generates a reaction force that rocks the separation roller unit 321 so that the separation roller 114 is separated from the feed roller 113 against the rotational force. In this way, the first transmission unit 323, the locking unit 324, and the second transmission unit 325 impart to the separation roller unit 321 a reaction force that rocks the separation roller unit 321 so that the separation roller 114 is separated from the feed roller 113 as the separation roller 114 rotates.

[0101] As described above in detail, even when using the separation roller unit 321, the first transmission part 323, the locking part 324 and the second transmission part 325, the medium feeding device is able to feed the medium better while suppressing increases in device cost, device size and device weight.

[0102] FIG. 9 is a diagram showing a schematic configuration of a processing circuit 450 of a medium feeding device according to another embodiment.

[0103] The processing circuit 450 is used in place of the processing circuit 150 of the medium feeding device 100, and executes medium reading processing and the like in place of the processing circuit 150. The processing circuit 450 has a control circuit 451, an image acquisition circuit 452, and the like. Note that each of these components may be composed of an independent integrated circuit, microprocessor, firmware, and the like.

[0104] The control circuit 451 is an example of a control unit, and has the same functions as the control unit 151. The control circuit 451 receives an operation signal from the operation device 105 or the interface device 132, and a medium signal from the medium sensor 111. The control circuit 451 controls the motor 131 based on each piece of received information.

[0105] The image acquisition circuit 452 is an example of an image acquisition section, and has the same function as the image acquisition section 152. The image acquisition circuit 452 acquires an input image from the imaging device 118, and outputs it to the interface device 132.

[0106] As described above in detail, even when the processing circuit 450 is used, the medium feeding device is able to feed the medium more satisfactorily while suppressing increases in the cost, size, and weight of the device.

[0107] Although the preferred embodiments have been described above, the embodiments are not limited thereto. For example, in the medium feeding device, the feeding roller may be disposed below the separation roller, and the medium placed on the placement table may be fed and transported in order from the bottom up. [Explanation of symbols]

[0108] 100 medium feeding device, 113 feeding roller, 114 separation roller, 115 torque limiter, 121, 221, 321 separation roller unit, 122 pressing portion, 123, 323 first transmission portion, 124, 324 engaging portion, 125, 225, 325 second transmission portion

Claims

1. A feed roller for feeding the medium; a separation roller disposed opposite the feed roller and provided on a rotation shaft to which no power is transmitted; a torque limiter provided on the rotating shaft, the torque limiter causing the separation roller to follow the feeding roller when a torque larger than a predetermined torque is applied thereto; a unit supporting the rotating shaft and arranged to be swingable; a pressing section that applies a pressing force to the unit to swing the unit so that the separation roller is pressed toward the feed roller; a reaction force generating unit configured to apply a reaction force to the unit for swinging the unit so that the separation roller is separated from the feed roller in accordance with the rotation of the separation roller; A medium feeding device comprising:

2. The reaction force generating portion is a first transmission unit provided on the rotation shaft and configured to transmit a rotational force in a direction in which the separation roller is driven by the feed roller; A locking portion fixed to the swing shaft of the unit; a second transmission portion that transmits the rotational force to the locking portion, The medium feeding device according to claim 1 , wherein the second transmission portion transmits the rotational force to the locking portion such that the reaction force is generated by the locking portion against the rotational force.

3. The medium feeding device according to claim 2 , wherein the first transmission portion, the locking portion, and the second transmission portion are gears.

4. the first transmission portion and the locking portion are gears, The medium feeding device according to claim 2 , wherein the second transmission portion is a cam having an arm that engages with each of the first transmission portion and the locking portion.

5. The medium feeding device according to any one of claims 1 to 4, wherein the pressing portion is an elastic member.

Images