Paper supply device

Abstract

The present invention provides a paper feeding device capable of suppressing paper feeding defects such as paper jams over a long period of time. The paper feeding device (1) has a feed roller (10) and a delay roller (20). On the outer peripheral surface (11) of the feed roller (10), a plurality of ribs (13) extending along the circumferential direction (C1) are provided, with the axial direction (S1) of the feed roller (10) and the circumferential direction (C1) as the main component. On the outer peripheral surface (21) of the delay roller (20), a plurality of circumferential ribs (23) extending along the axial direction (S2) of the delay roller (20) and the circumferential direction (C2) as the main component are provided, and a plurality of axial ribs (24) extending along the circumferential direction (C2) as the main component are provided. In the unfolded view of the outer peripheral surface of the delay roller (20) unfolded into a plane, the circumferential rib (23) extends in a straight line and the axial rib (24) extends in a straight line.

Description

Technical Field

[0001] This invention relates to a paper feeding device suitable for image forming apparatuses such as copiers, printers, multi-function peripherals, and fax machines. Background Technology

[0002] Image forming apparatuses such as copiers, printers, multifunction peripherals, and fax machines have various rollers (see, for example, Patent Document 1). As devices incorporating rollers, paper feeding devices, as described in Patent Document 1, for feeding paper sheet by sheet are known. Paper feeding devices, for example, include pickup rollers, feed rollers, and delay rollers.

[0003] For example, although the terminology varies depending on the person skilled in the art, in a paper feeding device known as FRR (Feed Reverse Roller) type, the pickup roller feeds paper from the tray to the separator. The separator has a feed roller, a delay roller, and a torque limiter. The delay roller is in pressurized contact with the feed roller. This separator prevents overlapping feeding of paper. More specifically, when a paper feeding command is issued, the pickup roller and the feed roller begin to rotate. At this time, the delay roller, which is in pressurized contact with the feed roller, also rotates with the feed roller. Paper fed from the tray by the pickup roller enters between the feed roller and the delay roller, and the paper is advanced while being pressurized by the feed roller and the delay roller. At this time, the delay roller is subjected to a rotational force by the torque limiter in the direction that returns the paper. This delay roller is usually rotated in the direction of paper feed by the rotational force from the feed roller with one sheet of paper in between. On the other hand, there is a possibility that two sheets of paper may be mistakenly fed by the pickup roller. In this case, when two sheets of paper enter between the feed roller and the delay roller, the delay roller is rotated by a predetermined torque applied in the direction that pushes the paper back towards the tray side, thus causing the paper in contact with the delay roller to return towards the tray side. As a result, only the paper in contact with the feed roller advances.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 62-65859 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] In such a paper feeding device, if the paper feeding action is repeated, paper dust and other fine powder will adhere to the surfaces of the feed roll and the delay roll. If such fine powder is present on the surfaces of the feed roll and the delay roll, the coefficient of friction of these roll surfaces will decrease, making it difficult to feed paper stably. As a result, poor paper feeding, such as paper jams, may sometimes occur.

[0009] Patent Document 1 describes a feed roller with fine grooves formed at predetermined intervals in the circumferential direction, extending in a generally arched shape from one end of the roller's axial direction towards the other. These grooves are provided to accommodate and discharge paper dust adhering to the surface of the paper. As described in Patent Document 1, structures are known that provide grooves on the roller to suppress the reduction of friction between the roller and the paper caused by fine powders such as paper dust. In such a paper feeding device, it is required to suppress poor paper feeding and paper jams more reliably and for a longer period of time. Furthermore, Patent Document 1 focuses only on a single roller and does not pay any attention to the relationship between rollers in a paper feeding device that includes multiple rollers such as feed rollers and delay rollers.

[0010] Against this background, one of the objectives of the present invention is to provide a paper feeding device that can suppress poor paper feeding, such as paper jams, over a long period of time.

[0011] Solution for solving the problem

[0012] The inventors of this application conducted in-depth research and discovered that improving the feed roller and delay roller by linking them together, rather than focusing on the individual rollers, is effective in suppressing poor paper feeding and paper jams, thus leading to this invention.

[0013] The present invention is based on the following paper feeding device.

[0014] (1) A paper feeding device, wherein,

[0015] The paper feeding device has the following features:

[0016] The feed roller is subjected to a driving force for conveying the paper; and

[0017] The delay roller, configured to rotate in conjunction with the feed roller by applying the driving force from the feed roller, is given a predetermined rotational resistance in the opposite direction to the direction of rotation in this coordinated rotation.

[0018] On the outer circumferential surface of the feed roller, a plurality of raised strips are provided along the circumferential direction of the feed roller, with the axial direction being the main component in both the axial and circumferential directions of the feed roller.

[0019] On the outer circumferential surface of the delay roller, a plurality of circumferential ribs are provided along the axial direction of the delay roller, which are ribs extending primarily in the circumferential and axial directions of the delay roller, and a plurality of axial ribs are provided along the circumferential direction, which are ribs extending primarily in the axial and circumferential directions of the delay roller.

[0020] In the unfolded view of the outer peripheral surface of the delay roller as a plane, the circumferential ribs extend in a straight line, and the axial ribs extend in a straight line.

[0021] (2) The paper feeding device according to (1), wherein,

[0022] The ribs of the feed roller extend along the axial direction of the feed roller.

[0023] The circumferential ribs of the delay roller extend along the circumferential direction of the delay roller, and the axial ribs of the delay roller extend along the axial direction of the delay roller.

[0024] (3) The paper feeding device according to (1) or (2), wherein,

[0025] The plurality of the circumferential convex strips are arranged at equal pitches in the axial direction of the delay roller.

[0026] The effects of the invention

[0027] According to the present invention, in a paper feeding device, poor paper feeding, such as paper jams, can be suppressed for a long period of time. Attached Figure Description

[0028] Figure 1 This is a schematic side view of a paper feeding device according to an embodiment of the present invention.

[0029] Figure 2 This is a schematic three-dimensional view of the feed roller and delay roller of the separation mechanism.

[0030] Figure 3 It is a planar unfolded diagram of a portion of the outer circumferential surface of the feed roller.

[0031] Figure 4 It is along Figure 3 The cross-sectional view along line IV-IV is a diagram showing the outer circumferential surface of the feed roller in a section orthogonal to the axial direction of the feed roller.

[0032] Figure 5 It is a planar unfolded diagram of the outer circumferential surface of the delay roller.

[0033] Figure 6 It is along Figure 5 The sectional view along line VI-VI is a diagram showing the outer circumferential surface of the delay roll in a section orthogonal to the axial direction of the delay roll.

[0034] Figure 7 It is along Figure 5 The sectional view along line VII-VII is a diagram showing the outer circumferential surface of the delay roll in a section parallel to the axial direction of the delay roll.

[0035] Figure 8 This is an unfolded view of the main part of the convex strip in a modified example of the feed roller.

[0036] Figure 9This is an unfolded view of the main parts of the circumferential and axial ribs in a modified example of a delay roller.

[0037] Figure 10 This is a schematic diagram of the evaluation device. Detailed Implementation

[0038] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Furthermore, in this specification and the drawings, structural elements having substantially the same functional structure are omitted from repeated description by using the same reference numerals.

[0039] First, a paper feeding device according to one embodiment of the present invention will be described. Figure 1 This is a schematic side view of a paper feeding device 1 according to an embodiment of the present invention. Figure 2 This is a schematic perspective view of the feed roller 10 and delay roller 20 of the separation mechanism 4. Figure 3 It is a planar unfolded view of a portion of the outer peripheral surface 11 of the feed roller 10. Figure 4 It is along Figure 3 The cross-sectional view along line IV-IV is a view showing the outer peripheral surface 11 of the feed roller 10 in a section orthogonal to the axial direction S1 of the feed roller 10. Figure 5 It is a planar unfolded view of the outer peripheral surface 21 of the delay roller 20. Figure 6 It is along Figure 5 The cross-sectional view along line VI-VI is a diagram showing the outer peripheral surface 21 of the delay roller 20 in a section orthogonal to the axial direction S2 of the delay roller 20. Figure 7 It is along Figure 5 The cross-sectional view along line VII-VII is a diagram showing the outer peripheral surface 21 of the delay roller 20 in a section parallel to the axial direction S2 of the delay roller 20.

[0040] Reference Figure 1 The paper feeding device 1 is provided in the image forming apparatus. Examples of such image forming apparatuses include copiers, printers, multifunction peripherals, and fax machines.

[0041] The paper feeding device 1 has a pickup roller 3 disposed above the paper tray 2 and a separation mechanism 4 adjacent to the pickup roller 3.

[0042] The paper tray 2 can hold multiple sheets of paper 5. The paper 5 is not limited to paper, but can also be other sheets such as plastic sheets that can be imaged by an image forming apparatus.

[0043] The pickup roller 3, for example, has a structure in which an elastomeric roller is mounted on the outer periphery of the spindle 3a, and is driven to rotate by an electric motor (not shown). When the pickup roller 3 is driven to rotate and the paper 5 on the paper tray 2 is fed out of the paper tray 2 by the rotation of the pickup roller 3, the paper 5 is fed to the separation mechanism 4.

[0044] The separation mechanism 4 is provided to feed the sheets of paper 5 fed from the pickup roller 3 one by one toward the image forming unit (not shown). The separation mechanism 4 is configured to feed out only one sheet of paper 5 when multiple sheets of paper 5 are fed from the pickup roller.

[0045] The separation mechanism 4 has a feed roller 10 and a delay roller 20.

[0046] The feed roller 10 is configured to rotate via an electric motor (not shown), from which a driving force for conveying the paper 5 is applied. The feed roller 10, by applying the aforementioned driving force to the paper 5 fed by the pick-up roller 3, propels the paper 5 toward the image forming unit. Figure 1 The feed roller 10 is an elastic roller wound around the outer periphery of the mandrel 6, and the outer periphery of the elastic roller is the outer periphery 11 of the feed roller 10.

[0047] Reference Figures 2-4 On the outer peripheral surface 11 of the feed roller 10, a plurality of protrusions 13 are provided along the circumferential direction C1, extending primarily of the axial direction S1 of the feed roller 10 and the axial direction S1 in the circumferential direction C1. In this case, "protrusions 13 extending primarily of the axial direction S1" means that, for the vector V1 connecting one end of the protrusion 13 to the other end in the length direction L1, which is the direction in which the protrusion 13 extends, the magnitude of the axial component V1S is greater than the magnitude of the circumferential component V1C. In other words, it means that the angle θ1 (minor angle) of the protrusion 13 relative to the axial direction S1 is less than 45°. Preferably, the angle θ1 is 30° or less, more preferably 15° or less, and particularly preferably zero (parallel to the axial direction S1) as in this embodiment. That is, in this embodiment, the protrusions 13 of the feed roller 10 extend parallel to the axial direction S1 of the feed roller 10. In the unfolded view of the outer peripheral surface 11 of the feed roller 10 as a plane, the protrusions 13 extend in a straight line. In this embodiment, the feed roller 10 is a knurled roller with a plurality of protrusions 13 arranged on the circumferential direction C1. Thus, the protrusions 13 extend with the axial direction S1 as the main component, and the feed roller 10, as a drive roller, can contact the paper 5 in a manner that pulls the paper 5 out. As a result, the transmission efficiency of the driving force from the feed roller 10 to the paper 5 can be further improved.

[0048] Reference Figure 1 , 25. 7. The delay roller 20 is configured to rotate in conjunction with the feed roller 10 by applying the aforementioned driving force from the feed roller 10. Furthermore, it is given a predetermined rotational resistance in the direction opposite to the rotational direction A2 during this in-conjunction rotation. The delay roller 20 is an elastic roller wound around the outer periphery of the mandrel 8, and the outer peripheral surface of the elastic roller is the outer peripheral surface 21 of the delay roller 20. The torque limiter 7 provides the aforementioned rotational resistance to the delay roller 20. Alternatively, the delay roller 20 may be driven to rotate in the direction opposite to the rotational direction A2 by an electric motor (not shown) via the torque limiter 7, or it may be configured not to be subject to a driving force from an electric motor. The outer peripheral surface 21 of the delay roller 20 is in pressurized contact with the outer peripheral surface 11 of the feed roller 10.

[0049] According to the above structure, if the feed roller 10 starts to rotate, the delay roller 20 rotates in conjunction with the feed roller 10 in the rotation direction A2. Paper 5 fed from the paper tray 2 by the pickup roller 3 enters between the feed roller 10 and the delay roller 20, and is advanced while being pressurized by the feed roller 10 and the delay roller 20. At this time, the delay roller 20 is normally rotated in the direction of feeding paper 5 (rotation direction A2) by the rotational force from the feed roller 10, with one sheet of paper 5 in between. On the other hand, there is a possibility that the pickup roller 3 may mistakenly feed out two (or more) sheets of paper 5. In this case, when two sheets of paper 5 enter between the feed roller 10 and the delay roller 20, the delay roller 20 does not rotate in the rotation direction A2 because it contacts the lower sheet of paper 5 and slides between the upper and lower sheets of paper 5, thus preventing the lower sheet of paper 5 from passing through. As a result, only the sheet of paper 5 that contacts the feed roller 10 advances out of the multiple sheets of paper 5.

[0050] The delay roller 20 is arranged parallel to the feed roller 10. On the outer circumferential surface 21 of the delay roller 20, a plurality of circumferential ribs 23 are provided along the axial direction S2, extending as ribs with the circumferential direction C2 as the main component of the axial direction S2 and the circumferential direction C2 of the delay roller 20. In this case, "circumferential ribs 23 extending as the main component of the circumferential direction C2" means that for any part of the vector V2 of the circumferential rib 23 in the length direction L2, which is the direction in which the circumferential rib 23 extends, the magnitude of the circumferential component V2C is greater than the magnitude of the axial component V2S. In other words, it means that the inclination angle θ2 (minor angle) of the circumferential rib 23 relative to the circumferential direction C2 is less than 45°. Preferably, the inclination angle θ2 is 30° or less, more preferably 15° or less, and particularly preferably zero (parallel to the circumferential direction C2) as in this embodiment. That is, in this embodiment, the circumferential ribs 23 of the delay roller 20 extend parallel to the circumferential direction C2 of the delay roller 20. In this embodiment, in the unfolded view where the outer peripheral surface 21 of the delay roller 20 is unfolded into a flat surface, the circumferential rib 23 extends in a straight line. Thus, by extending the circumferential rib 23 with the circumferential C2 as the main component, the delay roller 20, as the driven roller, can support the paper 5 in a more stable posture, and it is less likely for the paper 5 to get stuck, allowing for smooth transport.

[0051] In this embodiment, in addition to the circumferential ribs 23, axial ribs 24 are also provided on the outer peripheral surface of the delay roller 20. Thus, the delay roller 20 is a roller with a grid-like convex shape formed on its surface. The axial ribs 24 are ribs extending with axial S2 as the main component in both the axial direction S2 and the circumferential direction C2 of the delay roller 20, and multiple axial ribs 24 are provided along the circumferential direction C2. In this case, "axial ribs 24 extending with axial S2 as the main component" means that for any part of the vector V3 of the axial rib 24 in the length direction L3, which is the direction in which the axial rib 24 extends, the magnitude of the axial component V3S is greater than the magnitude of the circumferential component V3C. In other words, it means that the inclination angle θ3 (minor angle) of the axial rib 24 relative to the axial direction S2 is less than 45°. Preferably, the inclination angle θ3 is 30° or less, more preferably 15° or less, and particularly preferably zero (parallel to the axial direction S2) as in this embodiment. That is, in this embodiment, the axial ribs 24 of the delay roller 20 extend parallel to the axial direction S2 of the delay roller 20. In this embodiment, in the unfolded view of the outer peripheral surface 21 of the delay roller 20 as a plane, the axial ribs 24 extend in a straight line. According to this structure, in a preferred embodiment, the plurality of circumferential ribs 23 and the plurality of axial ribs 24 are arranged in a grid pattern.

[0052] As explained above, according to this embodiment, since the ribs 13 of the feed roller 10 extend primarily along the axial direction S1, a force reliably feeding the paper 5 can be applied to the paper 5 via the ribs 13. Therefore, the feed roller 10 can apply sufficient driving force to the paper 5 for an extended period. Furthermore, since the circumferential ribs 23 of the delay roller 20 extend primarily along the circumferential direction C2, the paper 5 is smoothly received by the delay roller 20 in a manner that prevents it from getting stuck, allowing it to move on the delay roller 20. Therefore, even during long-term use of the paper feeding device 1, feeding defects such as paper jams can be more reliably suppressed. Moreover, fine powders such as paper dust can be discharged into the groove 15 between the two ribs 13 of the feed roller 10 and the groove 25 between the two circumferential ribs 23 of the delay roller 20. Therefore, paper dust retention between the ribs 13 of the feed roller 10 and the circumferential ribs 23 of the delay roller 20 can be suppressed. Therefore, even under long-term use of the paper feeding device 1, the decrease in the coefficient of friction between the feed roll 10 and the delay roll 20 can be suppressed. As a result, the degree of rotational linkage of the delay roll 20 as it rotates with the feed roll 10 can be maintained at a high level for a long period. As a result, paper jams caused by a decrease in the rotational linkage (coupling performance) between the feed roll 10 and the delay roll 20 can be suppressed more reliably.

[0053] Assuming that a feed roller with a grid-like contact surface formed on its outer periphery is used as the feed roller, this feed roller is more prone to slippage between itself and the delay roller 20 during long-term use compared to the knurled feed roller 10. Furthermore, when a knurled roller like the feed roller 10 is used as the delay roller, this delay roller is more prone to jamming with the paper 5, leading to paper jams, compared to the aforementioned feed roller 10. Therefore, by implementing the unique configuration of this application—configuring the knurled feed roller 10 and arranging the delay roller 20, which includes circumferential ribs 23 with circumferential C2 as the main component, on the opposite side of the feed roller 10—poor paper feeding, such as paper jams, can be suppressed more reliably and for a longer period.

[0054] Furthermore, according to this embodiment, the rib 13 of the feed roller 10 extends along the axial direction S1 of the feed roller 10, the circumferential rib 23 of the delay roller 20 extends along the circumferential direction C2 of the delay roller 20, and the axial rib 24 of the delay roller 20 extends along the axial direction S2 of the delay roller 20. With this structure, high transmission efficiency of the driving force from the feed roller 10 to the paper 5 and smoother transport of the paper 5 on the delay roller 20 can be achieved in a balanced manner.

[0055] Furthermore, according to this embodiment, the plurality of circumferential ribs 23 and the plurality of axial ribs 24 of the delay roller 20 are arranged in a grid pattern. With this structure, the paper 5 can be placed on the delay roller 20 under its own weight with a more uniform surface pressure, and fine powder generated over long-term use can be reliably accumulated in the grooves 25 between the ribs 23 and 24. Thus, smooth transport of the paper 5 by the feed roller 10 and the delay roller 20 can be maintained for a long period.

[0056] Next, a more preferred embodiment of the feed roller 10 and the delay roller 20 will be described.

[0057]

[0058] Reference Figures 2-4 The material of the feed roller 10 can be, for example, polyurethane, EPDM, and other synthetic rubbers, which are types of synthetic rubber. The material of the feed roller 10 can also be a material other than synthetic rubber that has elasticity and can immediately return to its original shape after being deformed by a relatively small external force.

[0059] The hardness of the feed roller 10 is not particularly limited; for example, a hardness of 30 to 70 using a hardness tester A is preferred. If the hardness of A is less than the lower limit mentioned above, the rubber wear will be greater, and it will be unable to maintain the required shape. On the other hand, if the hardness of A exceeds the upper limit mentioned above, the clamping amount will be smaller, the coefficient of friction will be too low, and the required conveying force may not be ensured. The lower limit of the hardness of the feed roller 10 is preferably 40, and the upper limit of the hardness of the feed roller 10 is preferably 60. In addition, the hardness of the hardness tester A is a value measured according to JIS (Japanese Industrial Standard) K 6253:2006.

[0060] The feed roller 10 is provided with a rib 13 whose main component is axial S1. On the other hand, it is preferable not to provide a rib whose main component is circumferential C1. This is because if a rib whose main component is circumferential C1 is provided, slippage can easily occur between the rib and the paper during long-term use of the separating mechanism 4. However, it is also possible for the feed roller 10 to also provide a rib whose main component is circumferential C1. That is, it is also possible for the feed roller 10 to also provide a circumferential rib that extends at an angle of more than 45° relative to the axial S1 and is capable of contacting the paper 5. Even when such a circumferential rib is provided, it is preferable that the circumferential rib is of a very small length. In this case, "very small" can be exemplified by 10% or less and 5% or less of the total length of each rib 13 in the length direction L1 of the feed roller 10.

[0061] The outer peripheral surface 11 of the feed roller 10 has a cylindrical portion 12 and a protrusion 13 protruding from the cylindrical portion 12. The cylindrical portion 12 is, for example, cylindrical in shape. The cylindrical portion 12 is configured such that the height of the protrusion 13 is sufficiently high so as not to contact the paper 5.

[0062] Preferably, the ribs 13 are arranged at equal pitches on the circumferential C1 of the feed roller 10. Preferably, the arrangement pitch P1 of the ribs 13 on the circumferential C1 is 0.9 mm to 1.3 mm. If the arrangement pitch P1 is less than the lower limit mentioned above, the volume of the groove 15 is small, making it difficult to effectively discharge paper dust adhering to the paper surface. On the other hand, if the arrangement pitch P1 exceeds the upper limit mentioned above, the frequency of contact between the feed roller 10 and the paper 5 decreases during the rotation of the feed roller 10, making it easier for slippage to occur between the feed roller 10 and the paper 5. The lower limit of the arrangement pitch P1 of the ribs 13 is preferably 0.95 mm, and the upper limit of the arrangement pitch P1 is preferably 1.1 mm. Alternatively, the ribs 13 may be arranged at unequal pitches on the circumferential C1.

[0063] When viewed from the axial direction S1, it is preferable that each ridge 13 is formed in a trapezoidal shape, for example. If the ridge 13 is in such a shape, the driving force can be concentrated from the tip of the ridge 13 to the paper 5, thereby improving the efficiency of the driving force transmission. In addition, the shape of the ridge 13 when viewed from the axial direction S1 can be triangular, quadrilateral, involute, cycloidal, or other shapes.

[0064] Preferably, each rib 13 is formed over the entire area of ​​the outer peripheral surface 11 of the feed roller 10 along the axial direction S1. However, it is also possible that in one rib 13, the rib portion is formed intermittently along the axial direction S1.

[0065] The height h1 of the ridge 13 is the height of the ridge 13 in the radial direction of the feed roller 10, measured from the cylindrical portion 12, and is preferably 0.3 mm to 0.7 mm. If the height h1 is less than the lower limit mentioned above, the volume of the groove 15 between the ridges 13 is small, making it difficult to effectively discharge paper dust adhering to the paper surface. On the other hand, if the height h1 exceeds the upper limit mentioned above, the wear of the ridge 13 when the paper 5 repeatedly passes through the paper feeding device 1 is large, making it impossible to maintain the required shape, and reducing the efficiency of the driving force transmission from the feed roller 10 to the paper 5. The lower limit of the height h1 of the ridge 13 is preferably 0.4 mm, and the upper limit of the height h1 is preferably 0.6 mm.

[0066] Preferably, the width w1 of the tip of the ridge 13 on the circumferential C1 is 0.2 mm to 0.5 mm. Width w1 is, for example, the width of the portion of the paper 5 that contacts the paper when the paper feeding device 4 is new. If the width w1 is less than the lower limit mentioned above, the ridge 13 is too thin, the contact area between the paper 5 and the ridge 13 is small, and the friction (conveying force) decreases. On the other hand, if the width w1 exceeds the upper limit mentioned above, the circumferential length of the groove 15 between adjacent ridges 13 cannot be sufficiently ensured, making it difficult to discharge fine powder into the groove 15, thus reducing the friction (conveying force). The lower limit of the width w1 at the tip of the ridge 13 is preferably 0.3 mm, and the upper limit of the width w1 is preferably 0.4 mm.

[0067] Preferably, the inclination angle θx of the rib 13 viewed from the axial direction S1 is 36° or less (including zero). The inclination angle θx is the angle between a radial straight line extending from the center of the feed roller 10 towards the side surface of the rib 13 (the end face of the circumferential C1) and that side surface. If the inclination angle θx is less than 36°, the groove 15 can be made sufficiently deep, thus making it easy to store fine powder in the groove 15. This suppresses the decrease in the coefficient of friction of the rollers 10 and 20 due to fine powder. Preferably, the inclination angle θx is 20° or less (including zero).

[0068] A groove 15 is provided between the two protrusions 13 on the circumferential C1. The groove 15 is provided as a space for fine powder to fall off. As a result, it is possible to prevent the friction coefficient of the protrusions 13 from decreasing and thus failing to obtain sufficient friction for conveying the paper 5.

[0069]

[0070] Reference Figure 2 and Figures 5-7 As for the material of the delay roller 20, it can be the same material as that of the feed roller 10.

[0071] The hardness of the delay roller 20 is not particularly limited; for example, a hardness of 30 to 70 on a hardness tester A is preferred. If the hardness A is less than the lower limit mentioned above, the rubber wear will be greater, and it will be unable to maintain the required shape. On the other hand, if the hardness A exceeds the upper limit mentioned above, the clamping amount will be smaller, the coefficient of friction will be too low, and the required conveying force may not be ensured. The lower limit of the hardness of the delay roller 20 is preferably 40, and the upper limit of the hardness A of the delay roller 20 is preferably 60.

[0072] The outer peripheral surface 21 of the delay roller 20 has a cylindrical portion 22 and circumferential ribs 23 and axial ribs 24 protruding from the cylindrical portion 22. The cylindrical portion 22 is, for example, cylindrical in shape. The cylindrical portion 22 is configured such that the height of the ribs 23 and 24 is sufficiently high so as not to contact the paper 5.

[0073] Although the circumferential ribs 23 can be arranged with unequal pitch along the axial direction S2 of the delay roll 20, it is preferable that the circumferential ribs 23 are arranged with equal pitch along the axial direction S2 of the delay roll 20. This equal pitch arrangement makes the posture of the paper 5 on the delay roll 20 along the axial direction S2 more stable. Preferably, the arrangement pitch P2 of the circumferential ribs 23 along the axial direction S2 is 1.0 mm to 1.5 mm. A more preferred range for the arrangement pitch P2 is 1.1 mm to 1.4 mm. If the arrangement pitch P2 is less than the lower limit mentioned above, the volume of the trough 25 for containing fine powder cannot be sufficiently ensured, making it difficult to discharge fine powder into the trough 25 during long-term use. On the other hand, if the pitch P2 exceeds the upper limit mentioned above, the span of the contact between the delay roller 20 and the paper 5 in the axial direction S2 is large, the wrinkles of the paper 5 in the axial direction S2 are large, the contact pressure between the convex strip 13 of the feed roller 10 and the paper 5 is unstable, and the transmission efficiency of the driving force from the feed roller 10 to the paper 5 is reduced.

[0074] At the section orthogonal to circumferential C2 ( Figure 7 Preferably, each circumferential protrusion 23 is formed as a smooth curved shape (a curved shape protruding radially outward toward the delay roller 20) as a wavy surface. If the circumferential protrusion 23 has such a shape, it is easy to ensure sufficient area for receiving the paper 5 at the top of the circumferential protrusion 23, and the paper 5 can be fed out smoothly. Alternatively, in the cross section orthogonal to the circumferential C2, the shape of each circumferential protrusion 23 may be rectangular, triangular, involute, cycloidal, or other shapes.

[0075] Preferably, each circumferential rib 23 is formed over the entire area of ​​the outer peripheral surface 21 of the delay roller 20 on the circumferential C2. However, it is also possible that in one circumferential rib 23, the rib portion is formed intermittently on the circumferential C2.

[0076] The height h2 of the circumferential rib 23 is the height of the circumferential rib 23 in the radial direction of the delay roll 20, measured from the cylindrical portion 22, and is preferably 0.15 mm to 0.4 mm. If the height h2 is less than the lower limit mentioned above, the volume of the groove portion 25 is too small, making it difficult to effectively discharge paper dust adhering to the paper surface. On the other hand, if the height h2 exceeds the upper limit mentioned above, the depth of the groove portion 25 is too deep, making it difficult to demold during the manufacturing of the delay roll 20.

[0077] Preferably, the width w2 of the base of the circumferential rib 23 on the axial direction S2 is 0.8 mm to 1.0 mm. Width w2 is, for example, the width of the portion of the paper 5 that contacts the paper when the paper feeding device 4 is new. If the width w2 is less than the lower limit mentioned above, the wear of the rib 23 is greater, it cannot maintain the required shape, the contact pressure between the rib 13 of the feed roller 10 and the paper 5 decreases, and the transmission efficiency of the driving force decreases. On the other hand, if the width w2 exceeds the upper limit mentioned above, the axial length of the groove 25 between adjacent circumferential ribs 23 cannot be sufficiently ensured, and the capacity for accumulating fine powder is smaller. Furthermore, the junction of the circumferential rib 23 and the groove 25 corresponds to... Figure 7 The boundary between the upwardly convex and downwardly convex shapes in the cross-section shown.

[0078] While the axial protrusions 24 can be arranged with unequal pitches on the circumferential C2 of the delay roller 20, it is preferable to arrange them with equal pitches. Preferably, the arrangement pitch P3 of the axial protrusions 24 on the circumferential C2 is 1.0 mm to 1.5 mm. A more preferred range for the arrangement pitch P3 is 1.1 mm to 1.4 mm. If the arrangement pitch P3 is less than the lower limit mentioned above, the volume of the trough 25 for accommodating fine powder cannot be adequately ensured, making it difficult to discharge fine powder into the trough 25 during long-term use. On the other hand, if the arrangement pitch P3 exceeds the upper limit mentioned above, the frequency of contact between the delay roller 20 and the paper 5 decreases during the rotation of the delay roller 20, resulting in larger wrinkles in the paper 5 in the conveying direction, making it difficult to feed the paper 5 smoothly.

[0079] Viewed from the axial direction S2, it is preferable that each axial protrusion 24 is formed as a smooth curved shape (a curved shape protruding radially outward toward the delay roller 20) as a wavy surface. If the axial protrusion 24 has such a shape, it is easy to ensure sufficient area for receiving the paper 5 at the tip of the axial protrusion 24, and the paper 5 can be fed out smoothly. In addition, the shape of the axial protrusion 24 viewed from the axial direction S1 can be rectangular, triangular, involute, cycloidal, or other shapes.

[0080] Preferably, each axial rib 24 is formed over the entire area of ​​the outer peripheral surface 21 of the delay roller 20 along the axial direction S2. However, it is also possible that in one axial rib 24, the rib portion is formed intermittently along the axial direction S2.

[0081] Preferably, the height h3 of the axial protrusion 24 is the same as the height h2 of the circumferential protrusion 23.

[0082] Preferably, the width w3 of the base of the axial protrusion 24 on the circumferential C2 is 0.8 mm to 1.0 mm. Width w3 is, for example, the width of the portion of the paper 5 that contacts the paper when the paper feeding device 4 is new. If the width w3 is less than the lower limit mentioned above, the contact area between the axial protrusion 24 and the paper 5 is smaller, and the friction (transporting force) decreases. On the other hand, if the width w3 exceeds the upper limit mentioned above, the circumferential length of the groove 25 between adjacent axial protrusions 24 cannot be sufficiently ensured, the capacity for accumulating fine powder is smaller, it is difficult to discharge fine powder into the groove 15, and the friction (transporting force) of the outer circumferential surface 21 decreases. Furthermore, the junction of the circumferential protrusion 24 and the groove 25 corresponds to... Figure 6 The boundary between the upwardly convex and downwardly convex shapes in the cross-section shown.

[0083] A groove 25 is formed by the portion surrounded by circumferential ribs 23 and axial ribs 24 arranged in a grid pattern. The groove 25 is provided as a space for fine powder to fall off. This can suppress the situation where the friction coefficient of the outer peripheral surface 21 of the delay roller 20 decreases, causing the friction between the paper 5 and the delay roller 20 to become excessively small. The grooves 25 are preferably arranged regularly in the axial direction S2, preferably regularly in the circumferential direction C2, and more preferably regularly in both the axial direction S2 and the circumferential direction C2. In this case, "regularly" can also mean that the grooves 25 are arranged at equal pitches, or it can mean that the grooves 25 are arranged in a group with multiple pitches, and this group is repeated multiple times.

[0084] The embodiments of the present invention have been described above. However, the present invention is not limited to the embodiments and variations described above, and various modifications can be made within the scope of the claims.

[0085] (1) In the above embodiment, the rib 13 of the feed roller 10 is illustrated as being parallel to the axial direction S1. Furthermore, as an example of the above embodiment, the rib 13 is shown with an inclination angle θ1 less than 45°. When the inclination angle θ1 is 30°, the rib 13 is, for example, […]. Figure 8 The shape shown. Figure 8 This is an unfolded view illustrating the main part of the convex strip 13 in a modified example of the feed roller 10.

[0086] (2) Furthermore, in the above embodiment, the example described is that the circumferential rib 23 of the delay roller 20 extends along the circumferential direction C2, and the axial rib 24 extends along the axial direction S2. Furthermore, as an example of the above embodiment, the inclination angles θ2 and θ3 of the ribs 23 and 24 are described as being less than 45°. For example, when the inclination angles θ2 and θ3 are both 30°, for example... Figure 9 The shape shown. Figure 9This is an unfolded view illustrating the main parts of the circumferential rib 23 and the axial rib 24 in a modified example of the delay roller 20. Alternatively, the inclination angles θ2 and θ3 may be different from each other.

[0087] Example

[0088] As an image forming apparatus, the SP8400 manufactured by Ricoh Corporation is provided. The paper feeding device of this image forming apparatus has a feed roll driven by a drive motor and a delay roll connected to a support shaft via a torque limiter.

[0089] Furthermore, the following three types of rollers are prepared for use as feed rollers and / or delay rollers.

[0090] 1. Grinding roller

[0091] 2. Grid roller

[0092] 3. Knurling roller

[0093] <Common Structure of All Rollers>

[0094] The outer diameter is 20mm, the inner diameter is 12.4mm, and the axial length is 24mm. Furthermore, the hardness is A50 according to the Japanese Industrial Standard (JIS) hardness tester.

[0095] <1. Unique structure of the grinding roller>

[0096] A grinding roller is a roller whose outer circumferential surface is ground using a grinding wheel, resulting in grinding marks. Other specifications are shown below.

[0097] Material: EPDM (Ethylene Propylene Diene Monomer)

[0098] <2. Unique Structure of Grid Rollers>

[0099] As a grid roller, a roller used as a delay roller 20 is prepared. The specifications of the grid roller are as follows.

[0100] Material: EPDM (Ethylene Propylene Diene Monomer)

[0101] The configuration pitch P2 of the circumferential convex rib 23 is 1.3mm.

[0102] The cross-sectional shape of the circumferential convex strip 23 is a smooth, curved shape that protrudes radially outward toward the roller.

[0103] The height h2 of the circumferential convex strip 23 is 0.20mm.

[0104] The width w2 of the base of the circumferential convex strip 23 is 0.9 mm.

[0105] The inclination angle θ2 of the circumferential convex strip 23 is 0°.

[0106] The axial convex rib 24 has a pitch P3 of 1.3mm.

[0107] The shape of the axial rib 24: a smooth, curved shape that protrudes radially outward toward the roller.

[0108] The height h3 of the axial protrusion 24 is 0.20 mm.

[0109] The width w3 of the base of the axial protrusion 24 is 0.9 mm.

[0110] The inclination angle θ3 of the axial convex rib 24 is 0°.

[0111] <3. Unique Structure of Knurling Rollers>

[0112] As a knurling roller, a roller used as a feed roller 10 is prepared. The specifications of the knurling roller are as follows.

[0113] Material: EPDM (Ethylene Propylene Diene Monomer)

[0114] The pitch P1 of the convex strip 13 is 1.0mm.

[0115] Shape of protrusion 13: Trapezoidal shape

[0116] The height h1 of the protrusion 13 is 0.5mm.

[0117] The width w1 at the top of the protrusion 13 is 0.3mm.

[0118] The inclination angle θ1 of the convex strip 13 is 0°.

[0119] <Experimental Methods>

[0120] Comparative Examples 1 to 4 and Example 1 were prepared by setting the feed roller and delay roller of the paper feeding device to the combination of rollers shown in Table 1. Furthermore, using an image forming apparatus, each time a predetermined number of sheets of paper as shown in Table 1 are fed using the paper feeding device, the feed roller and delay roller are removed from the image forming apparatus and installed on... Figure 10 The evaluation device shown. Additionally, the paper described above is ordinary paper manufactured by Ricoh Corporation. Figure 10 This is a schematic diagram of the evaluation device.

[0121] Figure 10 The evaluation device shown includes: an electric motor; a feed roller support shaft, on which the output shaft of the electric motor is mounted and on which a feed roller is mounted; a delay roller support shaft, which is embedded in the delay roller; and a torque limiter, which is mounted on the delay roller support shaft and imparts a specified rotational resistance to the delay roller. The feed roller mounted on the evaluation device presses against the delay roller with a load of 400 gf. Furthermore, the torque limiter is configured to generate a resistance torque of 400 gf·cm when the delay roller and the feed roller rotate together.

[0122] Then, a camera is used to capture images of the feed roller and delay roller rotating in the evaluation device by driving an electric motor, thereby capturing the situation where the delay roller rotates in tandem (rotates together). Next, by observing the video, the rate of rotational linkage (%), which is the proportion of the delay roller's rotation relative to the feed roller's rotation, is calculated. Furthermore, the rate of rotational linkage (%) is defined by the following formula.

[0123] Rotational performance (%) = (Number of seconds for the feed roller to rotate one revolution / Number of seconds for the delay roller to rotate one revolution) × 100

[0124] Table 1 shows the number of sheets n (n = 0, 10,000, 20,000, 30,000, 50,000, 70,000, 100,000, 150,000, 200,000) fed by the paper feeding device and the associated rotational property (%) when feeding n sheets.

[0125] [Table 1]

[0126]

[0127] In this experiment, when the rotational property was 80% or more at the point where the number of sheets supplied (n) = 70,000, the result was ○. Furthermore, when the rotational property was 40% or more but less than 80% at the point where n = 70,000, the result was △. Additionally, when the rotational property was less than 40% at the point where n = 70,000 (including cases where the evaluation was terminated), the result was ×. The results are shown in Table 1.

[0128] Furthermore, if the rotational property is around 60%, while paper jams are less likely to occur in the paper feeding device, the paper transport performance tends to decrease. Therefore, the criterion for △ is set as described above. On the other hand, if the rotational property is less than 40%, the paper feeding device is prone to paper jams. Therefore, the criterion for × is set as described above.

[0129] For Comparative Example 1, the wear rate of the contact surfaces between the feed roll and the delay roll, as well as the rate of fine powder retention, was relatively fast. At the point of 30,000 sheets fed, the associated rotational property was less than 40%, and paper jams frequently occurred. Therefore, the test was terminated at 30,000 sheets fed, and the evaluation was ×. For Comparative Example 2, the rate of fine powder retention in the feed roll was relatively fast. At the point of 70,000 sheets fed, the associated rotational property was less than 70%. Therefore, the test was terminated, and the evaluation was △. For Comparative Example 3, the rate of friction reduction in the feed roll was relatively fast. At the point of 70,000 sheets fed, the associated rotational property was less than 40%, and paper jams frequently occurred. Therefore, the test was terminated at 70,000 sheets fed, and the evaluation was ×. For Comparative Example 4, the rate of fine powder retention in the delay roll was relatively fast. At the point of 100,000 sheets fed, the associated rotational property was far below 70%. Therefore, the test was terminated, and the evaluation was △.

[0130] In addition, although not described as a comparative example, in the case of a comparative example in which a knurling roller was used on the delay roller, the possibility of paper jamming due to the expected paper getting stuck in the groove of the knurling roller was high, so no test was conducted.

[0131] On the other hand, in Embodiment 1, the convex strips of the feed roller, which serves as a knurling roller, can apply sufficient driving force to the paper for a long period of time. Furthermore, the circumferential convex strips of the delay roller, which serves as a grid-shaped roller, ensure that the paper is smoothly received by the delay roller and can move on it in a manner that prevents jamming. Therefore, even when feeding 200,000 sheets, over 80% of the continuous rotational stability can be ensured without paper jamming. Thus, this embodiment demonstrates the ability to suppress feeding defects such as paper jams over a long period of time.

[0132] Industrial availability

[0133] This invention can be used as a paper feeding device.

[0134] Explanation of reference numerals in the attached figures

[0135] 1. Paper feeding device; 5. Paper; 10. Feed roll; 11. Outer circumferential surface of feed roll; 13. Feed roll rib; 20. Delay roll; 21. Outer circumferential surface of delay roll; 23. Circumferential rib (delay roll rib); 24. Axial rib (delay roll rib); A2. Rotation direction; C1. Circumferential direction of feed roll; C2. Circumferential direction of delay roll; S1. Axial direction of feed roll; S2. Axial direction of delay roll.

Claims

1. A paper feeding device, wherein, The paper feeding device has the following features: The feed roller is subjected to a driving force for conveying the paper; and The delay roller, configured to rotate in conjunction with the feed roller by applying the driving force from the feed roller, is given a predetermined rotational resistance in the opposite direction to the direction of rotation in this coordinated rotation. On the outer circumferential surface of the feed roller, a plurality of convex ribs are provided along the circumferential direction of the feed roller, with the axial direction as the main component. A groove is formed between two convex ribs. The convex ribs and the grooves are alternately arranged in the circumferential direction of the feed roller. In the unfolded view of the outer peripheral surface of the feed roller as a plane, the feed roller is formed into a knurled shape by the straight extension of the convex strips and the grooves. On the outer circumferential surface of the delay roller, a plurality of circumferential ribs are provided along the axial direction of the delay roller, which are ribs extending primarily in the circumferential and axial directions of the delay roller, and a plurality of axial ribs are provided along the circumferential direction, which are ribs extending primarily in the axial and circumferential directions of the delay roller. In the unfolded view of the outer peripheral surface of the delay roller as a plane, the circumferential ribs extend in a straight line, and the axial ribs extend in a straight line, so that the circumferential ribs and the axial ribs are arranged in a grid pattern in the delay roller.

2. The paper feeding device according to claim 1, wherein, The ribs of the feed roller extend along the axial direction of the feed roller. The circumferential ribs of the delay roller extend along the circumferential direction of the delay roller, and the axial ribs of the delay roller extend along the axial direction of the delay roller.

3. The paper feeding device according to claim 1 or 2, wherein, The plurality of the circumferential convex strips are arranged at equal pitches in the axial direction of the delay roller.

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