Media delivery device

Abstract

To provide a medium feeding device capable of more successfully feeding a medium.SOLUTION: A medium feeding device has a feed roller for feeding a medium, a separation roller made of a resin and disposed to face the feed roller, and a pressing part for pressing one of the feed roller and the separation roller against the other so that a nipping region is formed at a position where the feed roller and the separation roller come in contact with each other. A plurality of grooves arranged perpendicular to the feeding direction of the medium are formed on the surface of the feed roller. A pitch of the plurality of grooves is set such that at least one groove is always present in the nipping region during feeding of the medium. A width of the plurality of grooves is set to 0.5 mm or more, and a contact area ratio S is set to 0.5 or more, where the contact area ratio S is [(surface area of the feed roller in the nipping region)-(area of the grooves of the feed roller in the nip region)] / (surface area of the feed roller in the nip region).SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] This disclosure relates to a media feeding device. [Background technology]

[0002] Generally, media feeding devices such as scanners feed media while separating it using feeding rollers and separation rollers. The media fed by such devices may have foreign matter attached to it, such as paper dust, fillers, coating agents (pigments), and powders. When such media are fed, foreign matter attached to the surface of the media can adhere to the feeding rollers, reducing the friction coefficient of the rollers and potentially degrading feeding performance. Therefore, in recent years, feeding rollers with grooves capable of accommodating foreign matter have been developed.

[0003] A paper feed roller made of a rubber composition and having irregularities on its surface has been disclosed (see Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-106067 [Overview of the project]

[0005] Media feeding devices are required to be able to feed media more efficiently.

[0006] The media supply device according to this embodiment aims to supply the media more efficiently.

[0007] A media feeding device according to one aspect of the embodiment includes a feeding roller for feeding a medium, a separation roller positioned opposite the feeding roller, and a pressing portion that presses one of the feeding roller and the separation roller against the other such that a nip region is formed at the position where the feeding roller and the separation roller are in contact, and the surface of the separation roller is oriented in the direction of feeding the medium alongA plurality of configured grooves and a plurality of flat portions respectively disposed between the plurality of grooves are formed. A plurality of openings are respectively formed in the plurality of flat portions. The openings are set such that the contact area ratio P is 0.4 or more and 0.6 or less. The contact area ratio P is { (the area of the grooves of the separation roller in the nip region - the total area of the openings of the separation roller in the nip region)} / (the surface area of the separation roller in the nip region). Product - Ni / (the surface area of the separation roller in the nip region).

[0008] According to the present embodiment, the medium feeding device can feed the medium better.

[0009] The objects and effects of the present invention will be recognized and obtained by using the components and combinations particularly pointed out in the claims. Both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the present invention described in the claims.

Brief Description of the Drawings

[0010] [Figure 1] It is a perspective view showing the medium feeding device 100 according to the embodiment. [Figure 2] It is a diagram for explaining the conveyance path inside the medium feeding device 100. [Figure 3] It is a schematic diagram for explaining the force applied to each roller. [Figure 4] It is a schematic diagram for explaining the surface of each roller. [Figure 5] (A) and (B) are schematic diagrams for explaining the grooves of each roller. [Figure 6] (A) and (B) are graphs for explaining the contact area ratio S. [Figure 7] It is a graph for explaining the contact area ratio S. [Figure 8] (A), (B), and (C) are schematic diagrams for explaining the separation roller 113. [Figure 9]It is a graph showing the relationship between the moving speed and amplitude of the medium. [Figure 10] (A) and (B) are graphs for explaining the contact area ratio P. [Figure 11] It is a graph showing the relationship between frequency and sound pressure [Figure 12] It is a block diagram showing the schematic configuration of the medium feeding device 100. [Figure 13] It is a diagram showing the schematic configuration of the storage device 140 and the processing circuit 150. <000 / 0103>It is a flowchart showing an example of the operation of the medium reading process. [Figure 15] It is a schematic diagram for explaining the other separation roller 213. [Figure 16] It is a diagram showing the schematic configuration of the other processing circuit 350.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, a medium feeding device, a control 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.

[0012] [[ID=3 / 116>[[ID= / 117>

[0013] ​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 surface. Hereafter, "upstream" refers to the upstream of the media transport direction A1, and "downstream" refers to the downstream of the media transport direction A1.

[0014] The upper housing 102 is positioned to cover the top surface of the media feeding device 100 and is rotatably engaged with the lower housing 101 by a hinge so that it can be opened and closed when the media jams, when cleaning the inside of the media feeding device 100, etc.

[0015] 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.

[0016] 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.

[0017] Figure 2 is a diagram illustrating the transport path inside the media supply device 100.

[0018] The transport path inside the media feeding device 100 includes a media sensor 111, a feeding roller 112, a separation roller 113, a first transport roller 114, a first opposing roller 115, an imaging device 116, a second transport roller 117, and a second opposing roller 118, among others.

[0019] Note that the number of each of the feeding roller 112, separating roller 113, first conveying roller 114, first opposing roller 115, second conveying roller 117 and / or second opposing roller 118 is not limited to one, but may be multiple. In that case, the feeding roller 112, separating roller 113, first conveying roller 114, first opposing roller 115, second conveying roller 117 and / or second opposing roller 118 are each arranged in a line with spacing between them in the width direction A2 perpendicular to the media conveying direction.

[0020] 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.

[0021] The medium sensor 111 is positioned upstream of the feeding roller 112 and the separation roller 113. The medium sensor 111 has a contact detection sensor and detects whether or not a medium is placed on the mounting table 103. The medium sensor 111 generates and outputs a medium signal whose signal value changes depending on whether or not a medium is placed on the mounting table 103. Note that the 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 medium sensor 111.

[0022] The feeding roller 112 is provided on the lower housing 101 and separates and feeds the medium placed on the mounting table 103 from the bottom up. The feeding roller 112 is made of rubber, plastic or other resin, or metal such as iron. The separation roller 113 is a so-called brake roller or retard roller and is provided on the upper housing 102 and positioned opposite the feeding roller 112. The separation roller 113 is provided so as to be rotatable or stoppable in the opposite direction to the medium feeding direction. The separation roller 113 is made of rubber, plastic or other resin, or metal such as iron. Alternatively, the feeding roller 112 may be provided on the upper housing 102 and the separation roller 113 on the lower housing 101, and the feeding roller 112 may feed the medium placed on the mounting table 103 from the top up.

[0023] The first transport roller 114 and the first opposing roller 115 are positioned downstream of the feed roller 112 and the separation roller 113 in the medium transport direction A1. The first transport roller 114 is provided on the upper housing 102 and transports the medium supplied by the feed roller 112 and the separation roller 113 to the imaging device 116. The first transport roller 114 is made of rubber, plastic or other resin, or metal such as iron. The first opposing roller 115 is provided on the lower housing 101, below the first transport roller 114 and opposite to the first transport roller 114, and rotates in conjunction with the first transport roller 114. The first opposing roller 115 is made of rubber, plastic or other resin, or metal such as iron. Alternatively, the first transport roller 114 may be provided on the lower housing 101 and the first opposing roller 115 may be provided on the upper housing 102.

[0024] The imaging device 116 is an example of an imaging unit and is positioned downstream of the first transport roller 114 and the first opposing roller 115 in the media transport direction A1, and images the media transported by the first transport roller 114 and the first opposing roller 115. The imaging device 116 includes a first imaging device 116a and a second imaging device 116b, which are positioned opposite each other across the media transport path.

[0025] The first imaging device 116a has a line sensor using a 1:1 optical system type CIS (Contact Image Sensor) with CMOS (Complementary Metal Oxide Semiconductor) image sensors arranged linearly in the main scanning direction. The first imaging device 116a also has a lens that forms an image on the image sensor and an A / D converter that amplifies the electrical signal output from the image sensor and performs analog-to-digital (A / D) conversion. The first imaging device 116a captures the surface of the transported medium according to control from a processing circuit described later, generates an input image, and outputs it.

[0026] Similarly, the second imaging device 116b has a line sensor with a CIS of the 1:1 optical system type, which has CMOS image sensors arranged linearly in the main scanning direction. The second imaging device 116b also has a lens that forms an image on the image sensor and an A / D converter that amplifies the electrical signal output from the image sensor and performs analog-to-digital (A / D) conversion. The second imaging device 116b generates and outputs an input image by imaging the back surface of the transported medium according to the control from the processing circuit described later.

[0027] Furthermore, the media feeding device 100 may have only one of the first imaging device 116a and the second imaging device 116b, and may read only one side of the media. 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.

[0028] The second transport roller 117 and the second opposing roller 118 are positioned downstream of the imaging device 116, i.e., downstream of the feeding roller 112 and the separation roller 113, in the media transport direction A1. The second transport roller 117 is provided on the upper housing 102 and further transports the media transported by the first transport roller 114 and the first opposing roller 115 downstream, and discharges it to the discharge table 104. The second transport roller 117 is made of rubber, plastic or other resin, or metal such as iron. The second opposing roller 118 is provided on the lower housing 101, below the second transport roller 117 and opposite to the second transport roller 117, and rotates in conjunction with the second transport roller 117. The second opposing roller 118 is made of rubber, plastic or other resin, or metal such as iron. Alternatively, the second transport roller 117 may be provided on the lower housing 101 and the second opposing roller 118 may be provided on the upper housing 102.

[0029] 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 direction of arrow A4, i.e., the media feeding direction. The separation roller 113 rotates or stops in the direction of arrow A5, i.e., the opposite direction to the media feeding 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 are separated. This restricts the transport of media other than the separated media (preventing double feeding).

[0030] The medium is fed between the first transport roller 114 and the first opposing roller 115, guided by the lower guide 101a and the upper guide 102a. The medium is then fed between the first imaging device 116a and the second imaging device 116b as the first transport roller 114 rotates in the direction of arrow A6. The medium read by the imaging device 116 is then discharged onto the discharge platform 104 as the second transport roller 117 rotates in the direction of arrow A7.

[0031] Figure 3 is a schematic diagram illustrating the forces applied to the feeding roller 112 and the separating roller 113.

[0032] As shown in Figure 3, the media supply device 100 further includes a pressing member 119.

[0033] The pressing member 119 is an example of a pressing part, with one end attached to the upper housing 102 and the other end attached to the shaft which is the rotation axis of the separation roller 113, and presses the separation roller 113 toward the feeding roller 112. The pressing member 119 includes an elastic member such as a torsion coil spring and generates a pressing force W that presses the separation roller 113 toward the feeding roller 112. The pressing member 119 forms a nip region at the position where the feeding roller 112 and the separation roller 113 are in contact. The pressing member 119 may also include other spring members such as a leaf spring or a rubber member. Furthermore, the pressing member 119 may be provided to press the feeding roller 112 toward the separation roller 113. In this way, the pressing member 119 presses one of the feeding roller 112 and the separation roller 113 toward the other so that a nip region is formed at the position where the feeding roller 112 and the separation roller 113 are in contact.

[0034] Figure 4 is a schematic diagram illustrating the surfaces of the feeding roller 112 and the separation roller 113. Figure 4 is a perspective view of the feeding roller 112 and the separation roller 113 from the downstream side.

[0035] As shown in Figure 4, a plurality of grooves 112b are formed on the surface 112a of the feed roller 112 in the width direction A2 perpendicular to the medium transport direction, that is, perpendicular to the medium feeding direction (parallel to the shaft, which is the rotation axis of the feed roller 112). In other words, the plurality of grooves 112b are arranged in a manner with spacing between them in the medium feeding direction, with each groove extending in a direction perpendicular to the medium feeding direction. Note that perpendicular to the medium feeding direction is not limited to an angle of 90° with respect to the medium feeding direction, but also includes an angle of a predetermined angle (for example, an angle within the range of ±5°) relative to 90°. By arranging the grooves 112b perpendicular to the medium feeding direction on the surface 112a of the feed roller 112, the feed roller 112 can more efficiently peel off (scrape off) foreign matter adhering to the medium, and foreign matter can be more efficiently contained in the grooves 112b.

[0036] Furthermore, a plurality of grooves 113b are formed on the surface 113a of the separation roller 113, arranged in the media transport direction A1, that is, parallel to the media feeding direction (perpendicular to the shaft, which is the rotation axis of the separation roller 113). In other words, the plurality of grooves 113b are arranged in a manner perpendicular to the media feeding direction, with gaps between them, so that each groove extends in the media feeding direction. Note that being parallel to the media feeding direction is not limited to the angle with respect to the media feeding direction being 0°, but also includes being inclined at a predetermined angle (for example, an angle within the range of ±5°) relative to 0°. By arranging the grooves 113b on the surface 113a of the separation roller 113, the force with which the media is pushed back by the separation roller 113 increases, and the media feeding device 100 can suppress the occurrence of double feeding of the media. In particular, by arranging grooves 113b parallel to the medium feeding direction on the surface 113a of the separation roller 113, the position of the grooves 113b in the nip region N does not change when the separation roller 113 rotates, and the separation force is kept constant. As a result, the medium feeding device 100 can suppress the occurrence of double feeding of the medium.

[0037] Furthermore, because the extension direction of the groove 112b of the feeding roller 112 and the extension direction of the groove 113b of the separating roller 113 are different, interference between the grooves 112b and 113b is suppressed, preventing the separating roller 113 from bouncing (vibrating). As a result, the media feeding device 100 can suppress the occurrence of double feeding of the media.

[0038] Furthermore, because the extension direction of the groove 112b of the feeding roller 112 and the extension direction of the groove 113b of the separating roller 113 are mutually perpendicular, foreign matter that frays from the medium and extends in various directions is highly likely to be contained in one of the grooves.

[0039] Figure 5(A) is a schematic diagram illustrating the groove 112b of the feed roller 112. Figure 5(A) is a schematic diagram showing the area around the nip region of the feed roller 112 and the separation roller 113 viewed from the side.

[0040] As shown in Figure 5(A), on the surface 112a of the feed roller 112, a plurality of grooves 112b are formed along the circumferential direction at a constant pitch L1. The pitch L1 of the plurality of grooves 112b is set so that at least one groove 112b is always present in the nip region N during medium feeding. In addition, the width L2 of each groove 112b of the feed roller 112 is set to be 0.5 mm or more.

[0041] Observations of rollers returned due to media slippage in the user's operating environment, as well as rollers that developed media slippage during accelerated testing, revealed that over 90% of the clumps of paper fibers attached to the rollers were 0.5 mm or smaller. This indicates that during media feeding, the possibility of the entire fiber mass contained in the media, such as paper, detaching is low; rather, it is more likely that a portion of the fiber frays, rises to the surface of the media, and rubs against the roller, causing detachment. The media feeding device 100 can efficiently accommodate fibers attached to the surface 112a of the feeding roller 112 in the groove 112b by setting the width L2 of the groove 112b of the feeding roller 112 to 0.5 mm or more. As a result, the media feeding device 100 can reduce the friction coefficient between the surface 112a of the feeding roller 112 and the media by preventing fibers from adhering to the surface 112a of the feeding roller 112, thereby suppressing media slippage. Therefore, the media feeding device 100 can suppress the occurrence of media jams.

[0042] Figure 5(B) is a schematic diagram illustrating the groove 113b of the separation roller 113. Figure 5(B) is a schematic diagram showing the area around the nip region of the feeding roller 112 and the separation roller 113 as seen from the downstream side.

[0043] As shown in Figure 5(B), on the surface 113a of the separation roller 113, multiple grooves 113b are formed at a constant pitch L3 along the width direction A2. In addition, the width L4 of each groove 113b of the separation roller 113 is set to be 0.5 mm or more.

[0044] As described above, observation of the rollers where media slippage occurred revealed that more than 90% of the clumps of paper fibers adhering to the rollers were 0.5 mm or smaller. The media feeding device 100 can efficiently contain the fibers adhering to the surface 113a of the separation roller 113 in the groove 113b by setting the width L4 of the groove 113b of the separation roller 113 to 0.5 mm or larger. As a result, the media feeding device 100 can suppress the occurrence of media slippage caused by the adhesion of fibers to the surface 113a of the separation roller 113, which reduces the coefficient of friction between the surface 113a of the separation roller 113 and the media. Therefore, the media feeding device 100 can suppress the occurrence of media jams.

[0045] Furthermore, the contact area ratio S on the surface 112a of the feed roller 112 is set to be 0.5 or more. The contact area ratio S of the feed roller 112 is calculated by the following formula (1). Contact area ratio S = {(Surface area of ​​the feed roller 112 surface 112a in the nip region N - Area of ​​the groove 112b of the feed roller 112 in the nip region N)} / (Surface area of ​​the feed roller 112 surface 112a in the nip region N) (1)

[0046] Figures 6(A), (B), and 7 are graphs illustrating the contact area ratio S of the feed roller 112.

[0047] Figure 6(A) is a graph showing the relationship between the number of media fed by the feed roller and the coefficient of friction between the feed roller and the media after feeding that number of media. In Figure 6(A), the horizontal axis represents the number of media fed by the feed roller, and the vertical axis represents the coefficient of friction between the feed roller and the media after feeding that number of media. This feed roller is a roller that has no grooves and a coefficient of friction with the media of approximately 3.0 in its initial state (when no media has been fed yet). As shown in Figure 6(A), the coefficient of friction between the feed roller and the media decreases as the number of media fed increases, and the possibility of media slippage increases. In particular, accelerated tests in which a large amount of media with foreign matter attached was fed showed that the frequency of media slippage increased sharply when the coefficient of friction fell below 1.4.

[0048] The maximum static frictional force between two objects is calculated by multiplying the shear strength (which is a constant if the objects are made of the same material) by the actual contact area between the two objects. In other words, the frictional force between two objects is proportional to the contact area.

[0049] Figure 6(B) is a graph showing the relationship between the contact area ratio S of a grooved feed roller and the friction coefficient between the feed roller and the medium. In Figure 6(B), the horizontal axis represents the contact area ratio S of the feed roller, and the vertical axis represents the friction coefficient between the feed roller and the medium. As shown in Figure 6(B), a proportional relationship exists between the contact area ratio S and the friction coefficient. As described above, if the friction coefficient is less than 1.4, the frequency of medium slippage is high, so it is preferable that the friction coefficient be 1.4 or higher. Since a proportional relationship exists between the contact area ratio S and the friction coefficient, it is preferable that the contact area ratio S is greater than or equal to the value obtained by dividing the threshold friction coefficient (1.4) at which the frequency of medium slippage increases by the initial value (3.0) (1.4 / 3.0 ≈ 0.5). By setting the contact area ratio S of the feed roller 112 to 0.5 or higher, the medium feed device 100 can reduce the frequency of medium slippage during medium feed.

[0050] Figure 7 is a graph showing the relationship between the number of media supplied by the feed roller and the feeding force (feeding force) of the media supplied by the feed roller in an accelerated test in which a large amount of media contaminated with foreign matter is supplied. The horizontal axis of Figure 7 represents the number of media supplied by the feed roller, and the vertical axis represents the feeding force of the media supplied by the feed roller. The feeding force of the media supplied by the feed roller 112 is the force applied to the media supplied by the feed roller 112 in the direction of media supply, and is measured by attaching a tension gauge to the upstream end of the media supplied by the feed roller 112.

[0051] Graph 701 shows the graph for a feed roller with a contact area ratio S of 0.35. Graph 702 shows the graph for a feed roller with a contact area ratio S of 0.50. Graph 703 shows the graph for a feed roller with a contact area ratio S of 0.60. Graph 704 shows the graph for a feed roller with a contact area ratio S of 0.90. Graph 705 shows the graph for a feed roller with a contact area ratio S of 0.95.

[0052] To properly feed the media, a feeding force of 200 gf or more was required. As shown in Graph 701, the feeding roller with a contact area ratio S of 0.35 was able to generate sufficient feeding force and feed the media well in the initial state (when no media had been fed yet). However, with this feeding roller, the feeding force decreased rapidly each time media was fed, and after feeding about 200 sheets of media, the feeding force fell below 200 gf, making it impossible to feed the media properly. Also, as shown in Graphs 702, 703, and 704, the feeding rollers with contact area ratios S of 0.50, 0.60, or 0.80 were able to generate sufficient feeding force and feed the media well in the initial state and after feeding 1000 or more sheets of media. On the other hand, as shown in Graph 705, the feeding roller with a contact area ratio S of 0.95 was already unable to generate sufficient feeding force in the initial state and was unable to feed the media properly.

[0053] Therefore, as described above, by setting the contact area ratio S to 0.5 or higher, the feed roller 112 can feed the medium smoothly over a long period of time. It is also preferable to set the contact area ratio S to 0.9 or lower. This allows the feed roller 112 to continue feeding the medium smoothly over a long period of time from the initial state.

[0054] Furthermore, the contact area ratio S of the feed roller 112 is defined from equation (1) to the following equation (2), and the pitch L1 of the groove 112b of the feed roller 112 is defined from equation (2) to the following equation (3). Contact area ratio S = {(Pitch L1 of groove 112b of feed roller 112 - Width L2 of groove 112b of feed roller 112)} / (Pitch L1 of groove 112b of feed roller 112) (2) Pitch L1 of groove 112b of feed roller 112 = (width L2 of groove 112b of feed roller 112) / (1 - contact area ratio S) (3)

[0055] Since the minimum width L2 of the groove 112b of the feed roller 112 is 0.5 mm and the minimum contact area ratio S is 0.5, from equation (3), the minimum pitch L1 of the groove 112b of the feed roller 112 is 1.0 mm. Generally, the width of the nip region between the feed roller and the separation roller is set to a range of 4.0 mm or more and 6.0 mm or less. The pitch L1 of the groove 112b of the feed roller 112 is set so that at least one groove 112b is always present within the nip region N during medium feeding, so the maximum value of pitch L1 is 4.0 mm. Therefore, the pitch L1 of the multiple grooves 112b of the feed roller 112 is 1.0 mm or more and 4.0 mm or less.

[0056] The width L2 of the groove 112b of the feed roller 112 is defined from equation (3) to the following equation (4). Width L2 of groove 112b of feed roller 112 = (Pitch L1 of groove 112b of feed roller 112) × (1 - Contact area ratio S) (4)

[0057] Since the maximum pitch L1 of the groove 112b of the feed roller 112 is 4.0 mm and the minimum contact area ratio S is 0.5, from equation (4), the maximum width L2 of the groove 112b of the feed roller 112 is 2.0 mm. Therefore, the width L2 of the groove 112b of the feed roller 112 is 2.0 mm or less. Note that more than 95% of the hardwood pulp used as paper has a fiber length of 2.0 mm or less, and more than 50% of the softwood pulp used as paper has a fiber length of 2.0 mm or less. Therefore, by setting the width L2 of the groove 112b of the feed roller 112 to 2.0 mm, the media feeder 100 can accommodate most of the fibers of hardwood pulp and softwood pulp in the groove 112b of the feed roller 112.

[0058] As a result, the feeding roller 112 can efficiently contain foreign matter adhering to the feeding medium in the groove 112b, and continue to feed the medium smoothly for a long period of time from the initial state.

[0059] Figures 8(A), (B), and (C) are schematic diagrams illustrating the surface 113a of the separation roller 113. Figure 8(A) is a schematic diagram of the surface 113a of the separation roller 113 viewed from above, Figure 8(B) is a cross-sectional view taken along line A-A' in Figure 8(A), and Figure 8(C) is a cross-sectional view taken along line B-B' in Figure 8(A).

[0060] As shown in Figures 8(A), (B), and (C), the surface 113a of the separation roller 113 has multiple flat sections 113c, each positioned between multiple grooves 113b. Each of the multiple flat sections 113c has multiple openings 113d. Each opening 113d is formed by hollowing out a portion of the flat section 113c in a hemispherical (dome-shaped) form. That is, each opening 113d is formed in a circular shape when viewed from above. However, each opening 113d may be formed in any shape, such as an ellipse, rectangle, or triangle.

[0061] When the medium is fed, the surface 113a of the separation roller 113 vibrates due to the separation operation of the medium by the separation roller 113, and abnormal noises (so-called chirping sounds, slip-stick sounds) are generated around the separation roller 113. The chirping sound is a sound in a specific frequency band (for example, 3 kHz to 4 kHz, 6.5 kHz to 8 kHz, etc.).

[0062] Regarding the vibration system on the surface 113a of the separation roller 113, the frequency f of vibration<000028> ss ss ss k s ss

[0063] ss ss is calculated by the following formula (5), and the amplitude A of vibration ss is calculated by the following formula (6). f ss = kv / {2(μ s - μ k )W} (5) A ss =(μ s - μ k )W / k (6) Here, k is the rigidity (spring constant) of the surface 113a of the separation roller 113. v is the moving speed at which the medium moves with respect to the surface 113a of the separation roller 113. μ s is the static friction coefficient between the surface 113a of the separation roller 113 and the medium. μ k is the dynamic friction coefficient between the surface 113a of the separation roller 113 and the medium. W is the vertical load applied to the surface 113a of the separation roller 113. For the calculation of the frequency f ss and the amplitude A ss , please refer to "Ken Nakano, Satoru Maekawa, Soft Materials and Friction Vibration, The 177th Rubber Technology Symposium, The Rubber Society of Japan, p1-10 (2012)".

[0063] From formulas (5) and (6), the amplitude A of vibration ss is calculated by the following formula (7). A ss = v / 2f ss (7) As shown in formula (7), the amplitude A of the surface 113a of the separation roller 113 ss is proportional to the moving speed v of the medium with respect to the surface 113a of the separation roller 113.

[0064] Figure 9 shows the movement speed (processing speed) of the medium relative to the surface 113a of the separation roller 113 and the amplitude A of the surface 113a of the separation roller 113. ss This is a graph showing the relationship between [the two points].

[0065] The horizontal axis of Figure 9 shows the transfer speed (processing speed) of the medium relative to the surface 113a of the separation roller 113 [ppm], and the vertical axis shows the amplitude A of the vibration of the surface 113a of the separation roller 113. ss [mm] is shown. Graph 901 shows the frequency f of the vibration of the surface 113a of the separation roller 113. ss Amplitude A when the frequency is 3kHz ss This is shown. Graph 902 shows the frequency f ss Amplitude A when the frequency is 4kHz ss This is shown. Graph 903 shows the frequency f ss Amplitude A when the frequency is 5kHz ss This indicates.

[0066] Generally, the movement speed (processing speed) of the medium in a medium feeding device is 90 ppm or less. Therefore, as shown in Figure 9, the frequency f of the vibration of the surface 113a of the separation roller 113 is ss The amplitude A of the surface 113a of the separation roller 113 when the frequency is 3 kHz or higher and 5 kHz or lower. ss The diameter is 0.10 mm or less. By making the diameter (maximum width) d of the multiple openings 113d of the medium feeding device 100 0.10 mm or more, it is possible to block (reduce) the propagation of sound generated by vibrations of the surface 113a of the separation roller 113 on the surface 113a.

[0067] Furthermore, in general, to ensure good separation of the medium, the width L5 (see Figure 5(b)) of the multiple flat sections 113c, each positioned between the multiple grooves 113b on the surface 113a of the separation roller 113, is set to 1.0 mm or more. Conversely, if the diameter d of the opening 113d is too large, the medium will not be properly separated. An experiment was conducted using multiple separation rollers, each with a flat section width of 1.0 mm and different opening diameters, to feed the medium. As a result, the medium was properly separated when the opening diameter was 0.35 mm or less, but when the opening diameter was greater than 0.35 mm, the medium was not separated. Therefore, it is preferable that the diameter d of the multiple openings 113d be 0.35 mm or less.

[0068] Therefore, the diameter d of the multiple openings 113d is set to be between 0.10 mm and 0.35 mm. This allows the media feeding device 100 to suppress the generation of squeaking noise while effectively separating the media.

[0069] Furthermore, it is preferable that the depth H of the multiple openings 113d be 0.2 mm or more, so that the openings 113d remain even when the surface 113a of the separation roller 113 is worn.

[0070] Furthermore, generally, a separation roller is formed as an annular elastic body around a shaft, which is the axis of rotation. The annular elastic body includes two layers: an outer layer made of a non-foamed layer and an inner layer made of a foamed layer. In such a separation roller, the thickness (depth) of the outer layer is generally set to 1.0 mm or more and 1.5 mm or less. It is preferable that the depth H of the multiple openings 113d is 1.0 mm or less so that multiple openings 113d are formed in the outer layer of the separation roller 113.

[0071] Therefore, the depth H of the multiple openings 113d is set to be 0.2 mm or more and 1.0 mm or less. This allows the media feeding device 100 to form the openings 113d only on the outer layer of the separation roller 113, while still maintaining the openings 113d even if the surface 113a wears down.

[0072] Furthermore, the contact area ratio P on the surface 113a of the separation roller 113 is set to be 0.4 or greater. The contact area ratio P of the separation roller 113 is calculated by the following formula (8). Contact area ratio P = {(Surface area of ​​the surface 113a of the separation roller 113 in the nip region N - Area of ​​the groove 113b of the separation roller 113 in the nip region N - Total area of ​​the opening 113d of the separation roller 113 in the nip region N)} / (Surface area of ​​the surface 113a of the separation roller 113 in the nip region N) (8)

[0073] Figures 10(A), (B) and 11 are graphs illustrating the contact area ratio P of the separation roller 113.

[0074] Figure 10(A) is a graph showing the relationship between the load rate applied to the medium fed by the feed roller 112 and the separation roller 113 and the slip rate between the feed roller 112 and the medium. The horizontal axis of Figure 10(A) represents the load rate applied to the medium fed by the feed roller 112 and the separation roller 113, and the vertical axis represents the slip rate between the feed roller 112 and the medium. Graph 1001 shows the slip rate when the contact area ratio P of the separation roller 113 is 0.37, and graph 1002 shows the slip rate when the contact area ratio P of the separation roller 113 is 0.40.

[0075] The load factor η applied to the medium fed by the feeding roller 112 and the separation roller 113 is calculated by the following equation (9). η = F / W (9) Here, W is the force exerted by the pressing member 119 to press the separation roller 113 toward the feeding roller 112. F is the force exerted by the pressing force W on the medium being fed, on the side opposite to the medium transport direction A1.

[0076] The slip ratio R between the feed roller 112 and the medium is calculated by the following formula (10). R={(V r -V p ) / V r} × 100 (10) Here, Vr This is the peripheral speed of the feed roller 112 (the moving speed of the surface 112a of the feed roller 112). p This is the speed of movement across the surface of the medium.

[0077] When the slip ratio is 0%, the medium is fed without slipping against the feed roller 112, and when the slip ratio is 100%, the medium remains stationary despite the feed roller 112 rotating. The load ratio η when the slip ratio is 100%, i.e., the load ratio η when the medium is stationary, represents the coefficient of friction between the feed roller 112 and the medium, and the coefficient of friction between the separation roller 113 and the medium. That is, as shown in Graph 1001, when the contact area ratio P of the separation roller 113 is 0.37, the coefficient of friction between the separation roller 113 and the medium is approximately 0.9. Also, as shown in Graph 1002, when the contact area ratio P of the separation roller 113 is 0.40, the coefficient of friction between the separation roller 113 and the medium is approximately 1.0.

[0078] The driving force from the motor, described later, is transmitted to the separation roller 113 via a torque limiter. The limit value of this torque limiter is set such that the rotational force via the torque limiter is cut off when there is one medium, and the rotational force via the torque limiter is transmitted when there are multiple mediums. As a result, when only one medium is being transported, the separation roller 113 does not rotate according to the driving force from the motor, but follows the feed roller 112. On the other hand, when multiple mediums are being transported, the separation roller 113 rotates or stops in the opposite direction to the medium feeding direction, separating the medium in contact with the feed roller 112 from the other medium, thereby preventing double feeding. When only one medium is being transported, the separation roller 113 follows the feed roller 112, so that only a specific area of ​​the separation roller 113 continues to face the feed roller 112, thereby suppressing wear.

[0079] However, in order for the separation roller 113 to follow the feed roller 112, the coefficient of friction between the separation roller 113 and the medium must be 1.0 or greater, so the contact area ratio P of the separation roller 113 must be 0.40 or greater.

[0080] Figure 10(B) is a graph showing the relationship between the contact area ratio P of the separation roller 113 and the coefficient of friction between the separation roller 113 and the medium. In Figure 10(B), the horizontal axis represents the contact area ratio P of the separation roller 113, and the vertical axis represents the coefficient of friction between the separation roller 113 and the medium. As shown in Figure 10(B), a proportional relationship exists between the contact area ratio P and the coefficient of friction. As described above, if the coefficient of friction is less than 1.0, the separation roller 113 will not follow the feed roller 112 when only one medium is being transported. Therefore, it is preferable that the contact area ratio P of the separation roller 113 be 0.40 or higher so that the coefficient of friction is 1.0 or higher. By setting the contact area ratio P of the separation roller 113 to 0.40 or higher, the medium feeding device 100 can suppress wear on only specific areas of the separation roller 113 when the medium is being fed.

[0081] Figure 11 is a graph showing the relationship between frequency and sound pressure for the sound generated around the separation roller 113. In Figure 11, the horizontal axis represents frequency, and the vertical axis represents sound pressure. Graph 1101 shows the graph when media is fed using a separation roller with a contact area ratio S of 0.70. Graph 1102 shows the graph when media is fed using a separation roller with a contact area ratio S of 0.65. Graph 1103 shows the graph when media is fed using a separation roller with a contact area ratio S of 0.60. Graph 1104 shows the graph when no media is being fed.

[0082] As shown in Graphs 1101 and 1102, in separation rollers with a contact area ratio S of 0.70 or 0.65, loud noises (squeaking) are generated during media feeding in the frequency band R1 of 3kHz to 4kHz and its harmonics, the frequency band R2 of 6.5kHz to 8kHz. On the other hand, as shown in Graph 1103, in separation rollers with a contact area ratio S of 0.60, loud noises (squeaking) are not generated in the frequency bands R1 and R2 during media feeding. In other words, by setting the contact area ratio P of the separation roller 113 to 0.60 or less, the media feeding device 100 can suppress the generation of squeaking noises.

[0083] Therefore, it is preferable that the opening 113d of the separation roller 113 be set such that the contact area ratio P of the separation roller 113 is 0.4 or more and 0.6 or less. This allows the media feeding device 100 to suppress wear of the separation roller 113 during media feeding while suppressing the generation of squeaking noise.

[0084] Furthermore, it is preferable that two or more openings 113d are arranged in any line along the circumferential direction within the nip region N in the flat portion 113c of the separation roller 113. This allows the media feeding device 100 to suppress the generation of squeaking noise more effectively.

[0085] Furthermore, similar to the surface 112a of the feeding roller 112, it is preferable that the contact area ratio P on the surface 113a of the separating roller 113 be set to 0.5 or more. By setting the contact area ratio S of the separating roller 113 to 0.5 or more, the media feeding device 100 can reduce the frequency of media slippage during media separation.

[0086] Furthermore, the opening 113d on the surface 113a of the separation roller 113 may be omitted. In that case, the contact area ratio P of the separation roller 113 is calculated by the following formula (11). Contact area ratio P = {(Surface area of ​​the surface 113a of the separation roller 113 in the nip region N - Area of ​​the groove 113b of the separation roller 113 in the nip region N)} / (Surface area of ​​the surface 113a of the separation roller 113 in the nip region N) (11)

[0087] Furthermore, the contact area ratio P of the separation roller 113 is defined from equation (11) as shown in equation (12), and the pitch L3 of the groove 113b of the separation roller 113 is defined from equation (12) as shown in equation (13). Contact area ratio P = {(Pitch L3 of groove 113b of separation roller 113 - Width L4 of groove 113b of separation roller 113)} / (Pitch L3 of groove 113b of separation roller 113) (12) Pitch L3 of groove 113b of separation roller 113 = (width L4 of groove 113b of separation roller 113) / (1 - contact area ratio P) (13)

[0088] Since the minimum width L4 of the groove 113b of the separation roller 113 is 0.5 mm and the minimum contact area ratio P is 0.5, the minimum pitch L3 of the groove 113b of the separation roller 113 is 1.0 mm. Therefore, the pitch L3 of the multiple grooves 113b of the separation roller 113 is 1.0 mm or greater.

[0089] As a result, the separation roller 113 can efficiently collect foreign matter adhering to the supplied medium in the groove 113b, and continue to separate the medium well from the initial state over a long period of time.

[0090] Furthermore, similar to the groove 112b of the feed roller 112, the width L4 of the groove 113b of the separation roller 113 may be set to 2.0 mm or less. As described above, more than 95% of the hardwood pulp used as paper has a fiber length of 2.0 mm or less, and more than 50% of the softwood pulp used as paper has a fiber length of 2.0 mm or less. Therefore, by setting the width L4 of the groove 113b of the separation roller 113 to 2.0 mm, the media feeder 100 can accommodate most of the hardwood and softwood pulp fibers in the groove 112b of the feed roller 112. Also, similar to the groove 112b of the feed roller 112, the pitch L3 of the groove 113b of the separation roller 113 may be set to 4.0 mm or less.

[0091] Figure 12 is a block diagram showing the schematic configuration of the media supply device 100.

[0092] In addition to the configuration described above, the media supply device 100 further includes a motor 131, an interface device 132, a storage device 140, and a processing circuit 150.

[0093] The motor 131 has one or more motors and, in response to control signals from the processing circuit 150, rotates the feeding roller 112, the separating roller 113, the first conveying roller 114, and / or the second conveying roller 117 to convey the medium. The first opposing roller 115 and / or the second opposing roller 118 may be configured to rotate according to the driving force of the motor 131, rather than being driven by the first conveying roller 114 or the second conveying roller 117.

[0094] The interface device 132 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 132, 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.

[0095] The storage device 140 includes memory devices such as RAM (Random Access Memory) and ROM (Read Only Memory), fixed disk devices such as hard disks, or portable storage devices such as flexible disks and optical disks. The storage device 140 also stores computer programs, databases, tables, etc., used for various processes of the media supply device 100. The computer programs may be installed into the storage device 140 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).

[0096] The processing circuit 150 operates based on a program pre-stored in the memory device 140. 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 150.

[0097] The processing circuit 150 is connected to the operating device 105, display device 106, medium sensor 111, imaging device 116, motor 131, interface device 132, and storage device 140, and controls each of these components. Based on the medium signal received from the medium sensor 111, the processing circuit 150 performs drive control of the motor 131, imaging control of the imaging device 116, etc. The processing circuit 150 acquires the input image from the imaging device 116 and transmits it to the information processing device via the interface device 132.

[0098] Figure 13 shows a schematic configuration of the storage device 140 and the processing circuit 150.

[0099] As shown in Figure 13, the storage device 140 stores the control program 141, the image acquisition program 142, and the like. Each of these programs is a functional module implemented by software running on the processor. The processing circuit 150 reads each program stored in the storage device 140 and operates according to each program it has read. As a result, the processing circuit 150 functions as the control unit 151 and the image acquisition unit 152.

[0100] Figure 14 is a flowchart showing an example of the operation of the media reading process of the media supply device 100.

[0101] 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 14. The operation flow described below is mainly executed by the processing circuit 150 in cooperation with each element of the media supply device 100, based on a program pre-stored in the storage device 140.

[0102] First, the control unit 151 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 132 (step S101).

[0103] Next, the control unit 151 acquires a medium signal from the medium sensor 111 and determines whether or not a medium is placed on the mounting table 103 based on the acquired medium signal (step S102). If no medium is placed on the mounting table 103, the control unit 151 terminates the series of steps.

[0104] On the other hand, when a medium is placed on the mounting table 103, the control unit 151 drives the motor 131 to rotate the feeding roller 112, the separation roller 113, the first transport roller 114 and / or the second transport roller 117 (step S103). In this way, the control unit 151 feeds and transports the medium to each roller.

[0105] Next, the control unit 151 causes the imaging device 116 to image the medium, acquires an input image from the imaging device 116, and outputs the acquired input image by transmitting it to the information processing device via the interface device 132 (step S104).

[0106] Next, the control unit 151 determines whether or not there is any medium remaining on the mounting table 103 based on the medium signal received from the medium sensor 111 (step S105). If there is any medium remaining on the mounting table 103, the control unit 151 returns to step S104 and repeats the process from steps S104 to S105.

[0107] On the other hand, if there is no medium remaining on the mounting table 103, the control unit 151 controls the motor 131 to stop the feeding roller 112, the separation roller 113, the first transport roller 114 and / or the second transport roller 117 (step S106). Then the control unit 151 completes the series of steps.

[0108] As described in detail above, in the media feeding device 100, grooves 112b are formed in the feeding roller 112 to suppress the occurrence of media slippage while effectively accommodating foreign matter. As a result, the media feeding device 100 is able to feed the media more effectively.

[0109] Furthermore, in the media feeding device 100, grooves 113b and openings 113d are formed in the separation roller 113 to suppress wear on the separation roller 113 while suppressing the generation of squeaking noise. As a result, the media feeding device 100 can reduce the frequency of parts replacement and improve usability, thereby improving convenience for users.

[0110] In particular, the media feeding device 100 suppresses the generation of squeaking noise by providing an opening 113d (recess) on the flat portion 113c of the separation roller 113, rather than a protrusion on the surface 113a of the separation roller 113. Even if the separation roller 113 wears down, it takes a considerable amount of time for the entire flat portion 113c to wear away and the opening 113d to disappear, so the media feeding device 100 can suppress the generation of squeaking noise over a long period of time.

[0111] Figure 15 is a schematic diagram illustrating the surface 213a of the separation roller 213 in a media feeding device according to another embodiment.

[0112] The separation roller 213 shown in Figure 15 is used in place of the separation roller 113 of the media feeding device 100. The separation roller 213 has the same configuration as the separation roller 113. However, on the surface 213a of the separation roller 213, multiple openings 213d are formed in multiple flat portions 213c, each of which is positioned between multiple grooves 213b. The multiple openings 213d are arranged in a staggered pattern. This makes it possible for the media feeding device to efficiently and densely arrange the openings 213d on the surface 213a of the separation roller 213, thereby further suppressing the generation of squealing noise.

[0113] As detailed above, the media feeding device can now feed the media more effectively even when multiple openings 213d are arranged in a staggered pattern.

[0114] Figure 16 shows a schematic configuration of a processing circuit 350 in a media supply device according to yet another embodiment. The processing circuit 350 is used in place of the processing circuit 150 of the media supply device 100 and performs media reading processing, etc., instead of the processing circuit 150. The processing circuit 350 includes a control circuit 351 and an image acquisition circuit 352, etc. Each of these parts may be composed of an independent integrated circuit, microprocessor, firmware, etc.

[0115] The control circuit 351 is an example of a control unit and has the same functions as the control unit 151. The control circuit 351 receives operation signals from the operating device 105 or interface device 132 and medium signals from the medium sensor 111. The control circuit 351 controls the motor 131 based on the information it receives.

[0116] The image acquisition circuit 352 is an example of an image acquisition unit and has the same functions as the image acquisition unit 152. The image acquisition circuit 352 acquires an input image from the imaging device 116 and outputs it to the interface device 132.

[0117] As detailed above, the media supply device is now able to supply the media more efficiently, even when using the processing circuit 350.

[0118] With regard to the embodiments described above, the following additional information is disclosed.

[0119] (Note 1) A feed roller for feeding the medium, A separation roller made of resin and positioned opposite the feeding roller, The device has a pressing portion that presses one of the feeding roller and the separating roller against the other such that a nip region is formed at the position where the feeding roller and the separating roller come into contact. The surface of the separation roller has a plurality of grooves arranged parallel to the medium feeding direction, and a plurality of flat portions arranged between the plurality of grooves. Each of the aforementioned flat portions has a plurality of openings formed therein. The opening is set such that the contact area ratio P is 0.4 or more and 0.6 or less. The contact area ratio P is {(surface area of ​​the separation roller in the nip region) - (area of ​​the grooves of the separation roller in the nip region - total area of ​​the openings of the separation roller in the nip region)} / (surface area of ​​the separation roller in the nip region). A media supply and delivery device characterized by the following features.

[0120] (Note 2) The media supply device described in Appendix 1, wherein the plurality of openings are arranged in a staggered pattern.

[0121] (Note 3) The media supply device according to Appendix 1 or 2, wherein the diameter of the plurality of openings is 0.10 mm or more and 0.35 mm or less.

[0122] (Note 4) The media supply device according to any one of the appendices 1 to 3, wherein the depth of the plurality of openings is 0.2 mm or more and 1.0 mm or less.

[0123] (Note 5) A media feeding device according to any one of the appendices 1 to 4, wherein a plurality of grooves are formed on the surface of the feeding roller, arranged perpendicular to the direction of media feeding.

[0124] (Note 6) The pitch of the multiple grooves of the feed roller is set such that at least one groove is always present within the nip region during medium feeding. The width of the multiple grooves of the aforementioned feeding roller is set to be 0.5 mm or more, and the contact area ratio S is set to be 0.5 or more. The media feeding device according to Appendix 5, wherein the contact area ratio S is {(surface area of ​​the feeding roller in the nip region - area of ​​the groove of the feeding roller in the nip region)} / (surface area of ​​the feeding roller in the nip region). [Explanation of Symbols]

[0125] 100 Medium feeding device, 112 Feeding roller, 112a Surface, 112b Groove, 113 Separation roller, 113a Surface, 113b Groove, 119 Pressing member

Claims

1. A feed roller for feeding the medium, A separation roller positioned opposite the aforementioned feeding roller, The device has a pressing portion that presses one of the feeding roller and the separating roller against the other such that a nip region is formed at the position where the feeding roller and the separating roller come into contact. The surface of the separation roller is formed with a plurality of grooves arranged along the direction of medium feeding, and a plurality of flat portions arranged between each of the plurality of grooves. Each of the aforementioned flat portions has a plurality of openings formed therein. The opening is set such that the contact area ratio P is 0.4 or more and 0.6 or less. The contact area ratio P is {(surface area of ​​the separation roller in the nip region - area of ​​the groove of the separation roller in the nip region - total area of ​​the opening of the separation roller in the nip region)} / (surface area of ​​the separation roller in the nip region). A media supply and delivery device characterized by the following features.

2. The media supply device according to claim 1, wherein the plurality of openings are arranged in a staggered pattern.

3. The media supply device according to claim 1 or 2, wherein the diameter of the plurality of openings is 0.10 mm or more and 0.35 mm or less.

4. The media supply device according to any one of claims 1 to 3, wherein the depth of the plurality of openings is 0.2 mm or more and 1.0 mm or less.

5. The medium feeding device according to any one of claims 1 to 4, wherein a plurality of grooves are formed on the surface of the feeding roller, arranged in a direction intersecting the medium feeding direction.

6. The pitch of the multiple grooves of the feed roller is set such that at least one groove is always present within the nip region during medium feeding. The width of the multiple grooves of the aforementioned feeding roller is set to be 0.5 mm or more, and the contact area ratio S is set to be 0.5 or more. The media feeding device according to claim 5, wherein the contact area ratio S is {(surface area of ​​the feeding roller in the nip region - area of ​​the groove of the feeding roller in the nip region)} / (surface area of ​​the feeding roller in the nip region).

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