Sheet Feeding Device

Abstract

To provide a sheet feeder capable optimizing a separation load of a separation pad on a sheet, and separating thin paper and thick paper.SOLUTION: A sheet feeder comprises a feed roller 14 which feeds a plurality of sheets stacked at a loading part, and a separation pad 30 which is arranged opposite the feed roller 14 and separates the sheets sent by the feed roller 14 one by one. The separation pad 30 has a first separation part 31 which holds and separates a sheet with the feed roller 14, a second separation part 32 which comes into contact with the sheet and separates it at a position outside the feed roller in a width direction of the sheet, and an energization part 33 which is provided outside the second separation part 32 in the width direction and energizes the sheet toward the feed roller 14 in a thickness direction thereof.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a sheet feeding device that feeds a sheet. [Background technology]

[0002] Conventionally, in a sheet feeding device that feeds sheets one by one from a stacking tray, a separating member is provided to separate the sheets one by one so that multiple sheets are not fed into a conveying path while overlapping each other. As an example, a separating pad made of a sheet-shaped friction member is used as the separating member, and the sheets are separated by pressing the separating pad against the sheet stack.

[0003] Although a compression spring is sometimes used as a means for pressing the separation pad against the sheet, small-sized sheet conveying devices use a sponge to reduce space. A compression spring can adjust the force applied to thin paper and thick paper by reducing the spring constant, but a sponge has a large spring constant and the difference in force applied to thin paper and thick paper is large. Therefore, while a small-sized sheet conveying device can convey sheets of normal thickness such as copy paper, it may encounter a problem of being unable to feed thick paper such as postcards when conveying them. Therefore, a technology for optimizing the separation load on the sheet is proposed in Patent Document 1. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5378085 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the sheet feeding device described in Patent Document 1, the separation load varies depending on the thickness of the sheet, and therefore, some sheets may not be separated sufficiently. [Means for solving the problem]

[0006] In view of the above problems, a sheet feeding device according to the present invention has: A feed roller that feeds a plurality of sheets stacked on a stacking table; a separation pad disposed at a position facing the feed roller and configured to separate the sheets fed by the feed roller one by one; Equipped with The separation pad has a first separation portion that sandwiches and separates the sheet between the first separation portion and the feed roller, a second separation portion that contacts and separates the sheet at a position outside the feed roller in the width direction of the sheet, and a biasing portion that is provided outside the second separation portion in the width direction and biases the sheet toward the feed roller in the thickness direction. death, The biasing portion protrudes toward the sheet side from the second separation portion. It is characterized by: Effect of the Invention

[0007] It is possible to provide a sheet feeding device capable of separating a wide range of papers from thin papers to thick papers by optimizing the separation load on the separation pad for the sheets. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic cross-sectional view of an image reading apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram of a control unit of the image reading apparatus according to the embodiment. [Diagram 3] FIG. 4 is an enlarged perspective view of the separation pad and the feed roller according to the embodiment; [Figure 4] 4 is a diagram showing the separation pad according to the embodiment as viewed from the direction of the arrow A in FIG. 3. [Diagram 5] 4 is a cross-sectional view of the separation unit according to the embodiment, as viewed in the direction of the arrow C in FIG. 3. [Figure 6] 5 is a cross-sectional view of the separation unit according to the embodiment as viewed from the direction of arrow B in FIG. 4 (when thin paper is being conveyed). [Figure 7] 5 is a cross-sectional view of the separation unit according to the embodiment, seen from the direction of arrow B in FIG. 4 (when conveying cardboard); [Figure 8]4 is a view of a separation pad according to a second embodiment, viewed from the direction of arrow A in FIG. 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are examples for realizing the present invention, and the present invention is not limited to the following embodiments. The dimensions, materials, shapes, relative positions, etc. of the components of the present embodiment should be appropriately modified or changed depending on the configuration and various conditions of the device to which the present invention is applied, without departing from the spirit of the present invention. FIG. 1 is a schematic diagram of an image reading device 10 as an example of a sheet feeding device according to the present embodiment.

[0010] <Device configuration> The image reading device 10 is a device that transports one or more sheets S loaded on a loading platform 12 into the device one by one from a paper feed port, reads the images on the sheets, and discharges the sheets to the outside of the device by a drive roller 20 and a driven roller 21. The sheet S to be read is, for example, an office paper, a check, a business card, a card, or the like, and may be a thick or thin sheet.

[0011] <Paper Feed> A first conveying section 50 is provided as a sheet feeding mechanism that feeds the sheet S along the path RT. In this embodiment, the first conveying section 50 includes a feed roller 14 (feed roller) and a separation pad 30 disposed opposite the feed roller 14, and sequentially conveys the sheets S on the stacking table 12 one by one in a feeding direction D. A driving force is transmitted from a drive section 15 constituted by a motor or the like to the feed roller 14 via a transmission section (not shown), and the feed roller 14 is driven to rotate in the direction of the arrow in the figure (the direction in which the sheet S is conveyed).

[0012] <Drive unit> In the present embodiment, for example, the transmission unit connecting the drive unit 15 and the feed roller 14 is in a state in which the drive force is normally transmitted, and the drive force is interrupted when the sheet S is stopped. When the transmission of the drive force is interrupted by the transmission unit, the feed roller 14 is in a state in which it can rotate freely.

[0013] <Separated structure> The separation pad 30, which is disposed opposite the feed roller 14, is a member for separating the sheets S one by one, and is in pressure contact with the feed roller 14. To ensure this pressure contact state, a compressible sponge member 35 (elastic member) is provided on the separation pad 30. The sponge member 35 is configured to urge a first friction member 31 and a second friction member, which will be described later, toward the feed roller 14 by the elastic force of the sponge member 35.

[0014] <Conveyor structure> The second conveying section 51, which serves as a conveying mechanism located downstream of the first conveying section 50 in the conveying direction, has a drive roller 16 and a driven roller 17 driven by the drive roller 16, and conveys the sheet S conveyed from the first conveying section 50 downstream. A driving force is transmitted from the drive section 15 to the drive roller 16, and the drive roller 17 is driven to rotate. The driven roller 17 is in contact with the drive roller 16 with a constant pressure, and rotates together with the drive roller 16. The driven roller 17 may be configured to be biased against the drive roller 16 by a biasing unit (not shown) such as a spring.

[0015] The third conveying section 52, which is located downstream of the second conveying section 51 in the conveying direction, includes a drive roller 20 and a driven roller 21 that is driven by the drive roller 20, and discharges the sheet S conveyed from the second conveying section 51 to the outside of the apparatus. In other words, the third conveying section 52 functions as a discharge mechanism.

[0016] The driving roller 20 is rotated by a driving force transmitted from the driving unit 15. The driven roller 21 is in pressure contact with the driving roller 20 at a constant pressure, and rotates together with the driving roller 20. The driven roller 21 may be configured to be biased against the driving roller 31 by a biasing unit (not shown) such as a spring.

[0017] <Image reading structure and control> Here, in the image reading device 10 of this embodiment, the second conveying section 51 and the third conveying section 52 convey the sheet S at a constant speed because the image is read by the image reading units 18 and 19 disposed between the second conveying section 51 and the third conveying section 52. By always setting the conveying speed at this time to be equal to or higher than the conveying speed of the first conveying section 50, it is possible to reliably prevent the succeeding sheet S from catching up with the preceding sheet S. For example, in this embodiment, the reduction ratio of the transmission section that transmits the drive from the drive section 15 to the first conveying section 50 is set to be larger than the reduction ratio of the transmission section that transmits the drive from the drive section 15 to the second conveying section 51 and the third conveying section 52 so that the conveying speed of the sheet S by the second conveying section 51 and the third conveying section 52 is faster than the conveying speed of the sheet S by the first conveying section 50.

[0018] In addition, even if the conveying speed of the sheet S by the second conveying section 51 and the third conveying section 52 and the conveying speed of the sheet S by the first conveying section 50 are set to the same conditions, it is also possible to form a minimum gap between the preceding sheet S and the succeeding sheet S by controlling the drive section 15 to control only the drive of the first conveying section 50 and intermittently shifting the feed start timing of the succeeding sheet S.

[0019] <Registration sensor> The medium detection sensors 41 and 42 arranged downstream of the first conveying section 50 in the conveying direction are an example of a detection sensor (a sensor that detects the behavior or state of a sheet) arranged upstream of the image reading units 18 and 19 and downstream of the first conveying section 50 in the conveying path RT, and detect the position of the sheet S conveyed by the first conveying section 50, more specifically, whether or not the end of the sheet S has reached or passed the detection position of the medium detection sensors 41 and 42. Various types of medium detection sensors 41 and 42 can be used, but in this embodiment, they are optical sensors that have a light emitting section and a light receiving section and detect the sheet S based on the principle that the intensity of received light (amount of received light) changes when the sheet S reaches or passes through. Note that the medium detection sensors 41 and 42 are not limited to the optical sensors described above, and may be, for example, sensors (such as image sensors) that can detect the end of the sheet S, or may be lever-type sensors protruding into the path RT.

[0020] <CIS Arrangement> Image reading units 18 and 19, which are downstream of media detection sensors 41 and 42, optically scan, for example, convert into an electrical signal, and read as image data, and are equipped with a light source such as an LED, an image sensor, a lens array, etc. inside. In the case of this embodiment, image reading units 18 and 19 are arranged one on each side of path RT, and read the front and back surfaces of sheet S. However, it may be configured to arrange only one on one side of path RT and read only one side of sheet S. Also, in this embodiment, image reading units 18 and 19 are arranged opposite each other with path RT therebetween, but may be arranged at intervals in the conveyance direction of path RT, for example.

[0021] <Explanation of Block Diagram> The control unit 80 will be described with reference to FIG. 2. FIG. 2 is a block diagram of the control unit 80 of the image reading apparatus 10.

[0022] The control unit 80 includes a CPU 81, a storage unit 82, an operation unit 83, a communication unit 84, and an interface unit 85. The CPU 81 controls the entire image reading apparatus 10 by executing a program stored in the storage unit 82. The storage unit 82 is composed of, for example, a RAM, a ROM, etc. The operation unit 83 is composed of, for example, a switch, a touch panel, etc., and receives operations from an operator.

[0023] The communication unit 84 is an interface for information communication with an external device. When assuming a PC (personal computer) as the external device, examples of the communication unit 84 include a USB interface and a SCSI interface. Also, in addition to such a wired communication interface, a wireless communication interface may be used, or it may be equipped with both a wired communication and a wireless communication interface.

[0024] The interface unit 85 is an I / O interface that performs data input / output with the actuator 86 and the sensor 87. The actuator 86 includes a drive unit 15, a transmission unit, and the like. The sensor 87 includes media detection sensors 41, 42, image reading units 18, 19, and the like.

[0025] <Drive by receiving a start instruction from a PC> The basic operation of the image reading apparatus 10 will be described. When the control unit 80 receives an image reading start instruction from, for example, an external personal computer to which the image reading apparatus 10 is connected, the control unit 80 starts driving the first conveyance unit 50 to the third conveyance unit 52. The sheets S stacked on the stacking table 12 are conveyed one by one from the lowermost sheet S.

[0026] Also, as will be described later, the reading of an image may be started by a start key provided on the operation unit 83 of the image reading apparatus 10, and then the start of the image reading may be notified to the external personal computer.

[0027] <Start reading according to the output of the resist sensor> Based on the detection results of the media detection sensors 41 and 42, the control unit 80 starts reading the image of the sheet S by the image reading units 18 and 19 at a timing, temporarily stores the read image, and sequentially transmits it to the external personal computer. The sheet S from which the image has been read is discharged outside the apparatus by the third conveyance unit 52, and the image reading process of the sheet S is completed.

[0028] <Details of the separation pad> FIG. 3 is a perspective view for explaining the arrangement of the separation pad 30 and the feed roller 14 according to the first embodiment of the present invention. FIG. 3(a) shows the separation pad 30 and the feed roller 14 as viewed from the upstream side, and FIG. 3(b) shows only the separation pad 30 as viewed from the downstream side. FIG. 4 shows the separation pad 30 as viewed from the direction of the arrow A in FIG. 3. FIG. 5 is a cross-sectional view of the separation unit as viewed from the direction of the arrow C in FIG. 3. FIG. 6 is a cross-sectional view of the feed roller 14, the separation pad 30, and the sheet S as viewed from the direction of the arrow B in FIG. 4 when thin paper is being conveyed, and FIG. 7 is a cross-sectional view of the feed roller 14, the separation pad 30, and the sheet S as viewed from the direction of the arrow B in FIG. 4 when thick paper is being conveyed.

[0029] As shown in FIG. 3(a), the feed roller 14 has a plurality of roller members 14a (two in the figure) provided on a roller shaft 14b at intervals in the axial direction.

[0030] 4, the separation pad 30 includes a first friction member 31 and a second friction member 32 that separate the sheet S, and a biasing portion 33 that biases the sheet S toward the feed roller 14. The first friction member 31 has two roller contact portions 31b that respectively contact the two roller members 14a of the feed roller 14. The second friction member 32 is disposed outside the first friction member 31 in the axial direction of the roller shaft 14b, and contacts the sheet S together with the roller contact portion 31b.

[0031] As shown in FIG. 3(a), the second friction members 32 are arranged in two locations on the axially outer side of the two roller members 14a, at positions axially spaced apart from the roller members 14a so as to overlap (overlap) with the roller members 14a in the axial direction.

[0032] As shown in Fig. 3(b) and Fig. 4, the first friction member 31 and the second friction member 32 are formed by making four notches in a single flat rectangular friction member (rubber, for example). In addition, a pressing part 33 made of a flat rectangular low-friction member (a film member made of Mylar, for example) with four notches is attached to the pressing part 33. The outer part of the pressing part 33 in the axial direction of the roller member 14a, i.e., the part attached to the second friction member 32, protrudes less toward the downstream side in the feeding direction D shown in Fig. 4 than the second friction member 32, and further, a step is provided so that the protrusion amount on the inner side is smaller than the outer side in the axial direction.

[0033] 3(b), in this embodiment, a sponge member 35 is attached to the first friction member 31 and the second friction member 32 on the opposite side (back side) to the feed roller 14 in the thickness direction of the sheet S. The surface of the sponge member 35 on the opposite side to the first friction member 31 and the second friction member 32 is attached with double-sided tape 38 so as to abut against a holder 36.

[0034] As described above, the restoring force (elastic force) of the sponge member 35 urges the first friction member 31 and the second friction member 32 toward the feed roller 14, a nip is formed between the first friction member 31 and the feed roller 14, and the second friction member 32 protrudes in the axial direction to a position where it overlaps with the roller member 14a of the feed roller 14.

[0035] Furthermore, the urging portion 33, the first friction member 31, and the second friction member 32 on the upstream side in the feeding direction D are fixed to the holder 36 by sandwiching the holder 36 and the urging portion 33, the first friction member 31, and the second friction member 32 with a fixing metal plate 37. Note that, although the double-sided tape 38 is used to attach the sponge member 35 to the holder 36 and the fixing metal plate 37 is used to fix the urging portion 33, the first friction member 31, and the second friction member 32 on the upstream side to the holder 36, the present invention is not limited to this.

[0036] 4, the biasing portion 33, the second friction member 32, and the first friction member 31 are continuously arranged to form a comb-tooth shape. The biasing portion 33 is made of a member having a smaller friction coefficient than the first friction member 31 and the second friction member 32, and is attached to the feed roller 14 side in the thickness direction of the second friction member 32 as shown in FIG.

[0037] In a portion between the two first friction members 31 (a central portion in the width direction), the biasing portion 33 protrudes to the same extent as the second friction member 32 in the downward direction in FIG.

[0038] In the width direction, in the portion where the second friction member 32 is provided, the urging portion 33 is provided protruding halfway from the second friction member 32 toward the tip side of the second friction member 32, and a step is provided so that the outer side protrudes further downward (downstream in the feeding direction D) in Figure 4 than the inner side in the axial direction of the feed roller 14.

[0039] In this manner, the biasing portion 33 is disposed so as to come into contact with the sheet S when the sheet S is separated one by one by the first friction member 31 and the second friction member 32.

[0040] Next, the separation operation of the sheet S by the feed roller 14 and the separation pad 30 will be described with reference to FIGS. 5, 6, 7 and 8. FIG.

[0041] 4 and 5, the leading ends of the sheets S stacked on the stacking table 12 come into contact with the urging portion 33. When the feed roller 14 is rotated in the feeding direction by a driving means (not shown), the lower layer of the stack of sheets S abutting against the urging portion 33 advances to a nip portion between the roller member 14a of the feed roller 14 and the roller contact portion 31b of the first friction member 31. At that time, the first friction member 31 or the second friction member 32 and the base portion of the urging portion 33 guide the leading ends of the stack of sheets S to the nip portion between the roller member 14a and the roller contact portion 31b of the first friction member 31 while separating them so that the leading ends of the stack of sheets S are oblique.

[0042] At the same time as or after the sheet S passes through the nip portion between the roller member 14a and the roller contact portion 31b, the sheet S comes into contact with the second friction member 32 and the tip side (free end side) of the urging portion 33. At this time, the sheet S separated by the first friction member 31 comes into contact with the urging portion 33 and the second friction member 32, so that the sheets S in the lower layer are separated one by one and conveyed downstream in the feeding direction.

[0043] The contact pressure causes bending deformation of the second friction member 32 and the biasing portion 33. Note that a sheet separating portion is configured by disposing an elastically deforming member such as a sponge behind the member that contacts the sheet S (on the opposite side to the feed roller 14 in the thickness direction), and the sheet separating portion is caused to bend and deform by the contact pressure.

[0044] The separation operation of the sheet S by the feed roller 14 and the separation pad 30 when thin paper and thick paper are conveyed will be described with reference to FIGS.

[0045] The thin paper sheet S that has reached the nip portion with the roller contact portion 31b of the first friction member 31 is separated one by one by contact between the second friction member 32, the roller contact portion 31b of the first friction member 31, and the urging portion 33, as shown in Fig. 6. The thin paper sheet S is weak in stiffness and is flexed and deformed in a wavy manner in the width direction, so it comes into sufficient contact with the second friction member 32 and a large separation load acts on it. On the other hand, the thick paper sheet S that has reached the nip portion with the roller contact portion 31b of the first friction member 31 is separated one by one by contact between the roller contact portion 31b of the first friction member 31 and the urging portion 33, as shown in Fig. 7. The thick paper sheet S is strong in stiffness and does not flex easily, so it is difficult to come into contact with the second friction member 32, and the separation load is smaller for the thick sheet S than for the thin sheet S.

[0046] As a result, a large separation load acts on a thin sheet S because the contact area of ​​the second friction member 32 is large, and a small separation load acts on a thick sheet S because the contact area of ​​the second friction member 32 is small. Therefore, even for a thick sheet S, it is possible to avoid an excessive separation load from acting, and the separation load is optimized according to the thickness of the sheet S.

[0047] The configuration of the present invention is not limited to the above-mentioned embodiment, and the material, shape, size, form, number, arrangement, etc. can be appropriately changed within the scope of the present invention. For example, in the above-mentioned embodiment, the root portion of the second friction member 32 in the urging portion 33 is made to protrude toward the tip side (free end side) of the second friction member 32 on the outside rather than the inside in the axial direction, so that the friction by the second friction member 32 is large for thin paper with low stiffness and the friction by the second friction member 31 is small for thick paper with high stiffness, but any other configuration that can obtain a similar effect is acceptable. As an example, the number of linearly formed urging portions 33 on the outside may be greater than on the inside, or the urging portions 33 may be wave-like protruding from the outside toward the inside.

[0048] In addition, the shape of the base portion of the second friction member 32 in the urging portion 33 is such that it extends to the downstream side with the same width, but it is also possible to make the downstream end narrower as it approaches the downstream side in the feed direction, as shown in Fig. 8. Specifically, the outer side is provided to protrude downward (downstream side in the feed direction D) in Fig. 8 more than the inner side in the axial direction of the feed roller 14. In other words, the inner end in the width direction of the urging portion 33 is provided to be positioned outward as it approaches the downstream side in the feed direction D.

[0049] Although the present invention has been described above based on one embodiment, the present invention is not limited to the above-mentioned embodiment. In the above-mentioned embodiment, an image reading device having a separation pad 30 has been described as an example, but the present invention is of course not limited to this, and may be, for example, a sheet feeding device (such as a sheet feeder) that separates and feeds sheets, and may be widely applied to general office machines such as image processing devices (printers, multifunction devices, FAX machines, etc.) other than image reading devices that are equipped with such a sheet feeding device. [Explanation of symbols]

[0050] S Seat D Feeding direction 10 Image reader 12 Loading platform 14 Feed roller 14a Roller shaft 14b Roller member 30 Separation Pad 31 1st separation section 31b Roller contact part 32 Second separation section 33 Pressurizing section

Claims

1. A feed roller that feeds a plurality of sheets stacked on a stacking table; a separation pad disposed at a position facing the feed roller and configured to separate the sheets fed by the feed roller one by one; Equipped with the separation pad has a first separation portion that sandwiches and separates the sheet between the first separation portion and the feed roller, a second separation portion that contacts and separates the sheet at a position outside the feed roller in the width direction of the sheet, and a biasing portion that is provided outside the second separation portion in the width direction and biases the sheet toward the feed roller in the thickness direction of the sheet, The sheet feeding device, wherein the biasing portion protrudes toward the sheet from the second separation portion.

2. the second separation portion has an elastic member having an elastic force directed toward the feed roller, and the biasing portion is a flat-plate-shaped biasing portion attached to the elastic member on the feed roller side, 2. The sheet feeding device according to claim 1, wherein an area of ​​a surface of the urging portion that contacts the sheet is larger on an outer side than on an inner side in the width direction.

3. 3. The sheet feeding device according to claim 2, wherein a friction coefficient of a surface of the biasing portion that contacts the sheet is smaller than a friction coefficient of a surface of the elastic member that contacts the sheet.

4. 4. The sheet feeding device according to claim 2, wherein the biasing portion is a film member attached to a surface of the elastic member.

5. 5. The sheet feeding device according to claim 1, wherein an inner end of the urging portion in the width direction is positioned more outward in the width direction toward a downstream side in the sheet feeding direction.

Images