CN117279848A

CN117279848A - Paper feeder

Info

Publication number: CN117279848A
Application number: CN202280027796.2A
Authority: CN
Inventors: 鬼塚智之
Original assignee: Yamauchi Corp
Current assignee: Yamauchi Corp
Priority date: 2021-04-16
Filing date: 2022-02-04
Publication date: 2023-12-22
Also published as: WO2022219894A1; JP7374506B2; JP2022164161A; KR20230157468A

Abstract

The invention provides a paper feeding device capable of inhibiting poor paper conveyance such as jam for a long time. The paper feeding device (1) has a feed roller (10) and a retard roller (20). A plurality of protruding strips (13) which extend with the axial direction (S1) of the feed roller (10) and the axial direction (S1) in the circumferential direction (C1) as main components are arranged on the outer peripheral surface (11) of the feed roller (10) along the circumferential direction (C1). A plurality of circumferential protruding strips (23) which are extended with the circumferential direction (C2) of the axial direction (S2) and the circumferential direction (C2) of the delay roller (20) as main components are arranged on the outer circumferential surface (21) of the delay roller (20) along the axial direction (S2), and a plurality of axial protruding strips (24) which are extended with the axial direction (S2) of the axial direction (S2) and the circumferential direction (C2) as main components are arranged along the circumferential direction (C2). In an expanded view in which the outer peripheral surface of the retard roller (20) is expanded to a flat surface, the circumferential ridge (23) extends linearly, and the axial ridge (24) extends linearly.

Description

Paper feeder

Technical Field

The present invention relates to a paper feeder suitable for use in image forming apparatuses such as copiers, printers, multifunction peripherals, facsimile machines, and the like.

Background

Image forming apparatuses such as copiers, printers, multifunction peripherals, and facsimile machines have various rollers (for example, refer to patent document 1). As a device including a roller, a paper feeding device for feeding paper sheet by sheet as described in patent document 1 is known. The paper feeding device includes, for example, a pickup roller, a feed roller, and a retard roller.

For example, although called different according to a person skilled in the art, in a paper feeding device called an FRR (reverse feed roller) system, a pickup roller conveys a paper from a tray to a separating portion. The separating section has a feed roller, a retard roller, and a torque limiter. The retard roller is in pressurized contact with the feed roller. The separating portion prevents overlapped feeding of sheets. More specifically, when a paper feed instruction is issued, the pickup roller and the feed roller start to rotate. At this time, the retard roller in contact with the feed roller in a pressurized state also rotates together with the feed roller. The sheet fed out from the tray by the pickup roller enters between the feed roller and the retard roller, and advances while being pressurized by the feed roller and the retard roller. At this time, the retard roller is applied with a rotational force by the torque limiter in a direction to return the sheet. The retard roller is normally rotated in a direction of feeding out the sheet by receiving a rotational force from the feed roller through one sheet. On the other hand, there are cases where two sheets are erroneously fed out by the pickup roller. In this case, when two sheets enter between the feed roller and the retard roller, since the retard roller is applied with a predetermined torque in a direction of pushing the sheets back toward the tray side, it is rotated by the rotation of the torque, and the sheet in contact with the retard roller is returned toward the tray side. As a result, only the sheet in contact with the feed roller advances.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 62-65859

Disclosure of Invention

Problems to be solved by the invention

In such a paper feeding apparatus, when the paper feeding operation is repeated, paper dust or the like adheres as fine powder to the surface of the feed roller and the surface of the retard roller. If such fine powder exists on the surfaces of the feed roller and the retard roller, the friction coefficient of the surfaces of these rollers decreases, and it is difficult to stably convey the paper. As a result, a conveyance failure of the paper such as a jam may occur.

The paper feed roller described in patent document 1 is formed with fine grooves extending in a substantially arch shape from one end to the other end in the axial direction of the roller at predetermined intervals in the circumferential direction. The fine groove is provided for receiving and discharging paper dust adhering to the surface of the paper. As described in patent document 1, a structure is known in which grooves are provided in rollers in order to suppress a decrease in friction force between the rollers and paper due to fine powder such as paper dust. In such a paper feeding apparatus, it is required to suppress paper conveyance failure and paper jam for a longer period of time and more reliably. In addition, in patent document 1, attention is paid only to a single roller, and no attention is paid to the relationship between rollers in a paper feeding device including a plurality of rollers such as a feed roller and a retard roller.

In view of such a background, an object of the present invention is to provide a paper feeding device capable of suppressing a paper conveyance failure such as a jam for a long period of time.

Solution for solving the problem

As a result of intensive studies, the inventors of the present application have found that improvement of a feed roller and a retard roller in association with each other is effective in suppressing a defective conveyance or a jam of a sheet without focusing on individual rollers of the feed roller and the retard roller, and have arrived at the present invention.

The present invention is directed to the following paper feeding apparatus.

(1) A paper feeding device, wherein,

the paper feeding device comprises:

a feed roller to which a driving force for conveying the sheet is applied; and

a retard roller configured to be rotatable in conjunction with the feed roller by applying the driving force from the feed roller, the retard roller being configured to impart a predetermined rotational resistance in a direction opposite to a rotational direction during the cooperative rotation,

a plurality of convex strips which are extended by taking the axial direction of the feeding roller and the axial direction in the circumferential direction as main components are arranged on the outer circumferential surface of the feeding roller along the circumferential direction of the feeding roller,

a plurality of circumferential ridges as ridges extending mainly in the circumferential direction of the retard roller are provided on the outer circumferential surface of the retard roller along the axial direction of the retard roller, and a plurality of axial ridges as ridges extending mainly in the axial direction of the retard roller and the axial direction of the retard roller are provided along the circumferential direction,

in an expanded view in which the outer peripheral surface of the retard roller is expanded to a flat surface, the circumferential ridge extends linearly, and the axial ridge extends linearly.

(2) The paper feeding device according to the item (1), wherein,

the ribs of the feed roller extend in the axial direction of the feed roller,

the circumferential ridge of the retard roller extends along the circumferential direction of the retard roller, and the axial ridge of the retard roller extends along the axial direction of the retard roller.

(3) The paper feeding device according to the above (1) or the above (2), wherein,

the plurality of circumferential ridges are arranged at equal pitches in the axial direction of the retard roller.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, in the paper feeding device, it is possible to suppress a conveyance failure of paper such as a jam for a long period of time.

Drawings

Fig. 1 is a schematic side view of a sheet feeding device according to an embodiment of the present invention.

Fig. 2 is a schematic perspective view of a feed roller and a retard roller of the separation mechanism.

Fig. 3 is an expanded view of expanding a portion of the outer peripheral surface of the feed roller into a plane.

Fig. 4 is a cross-sectional view taken along line IV-IV of fig. 3, and is a view showing the outer peripheral surface of the feed roller in a cross-section orthogonal to the axial direction of the feed roller.

Fig. 5 is an expanded view of expanding the outer peripheral surface of the retard roller into a flat surface.

Fig. 6 is a cross-sectional view taken along line VI-VI of fig. 5, and is a view showing the outer peripheral surface of the retard roller in a cross section orthogonal to the axial direction of the retard roller.

Fig. 7 is a cross-sectional view taken along line VII-VII of fig. 5, and is a view showing the outer peripheral surface of the retard roller in a cross-section parallel to the axial direction of the retard roller.

Fig. 8 is an expanded view for explaining a main portion of the convex strip in the modified example of the feed roller.

Fig. 9 is an expanded view for explaining main portions of the circumferential ridge and the axial ridge in the modification of the retard roller.

Fig. 10 is a schematic diagram of the evaluation apparatus.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and overlapping description thereof is omitted.

First, a sheet feeding device according to an embodiment of the present invention will be described. Fig. 1 is a schematic side view of a sheet feeding device 1 according to an embodiment of the present invention. Fig. 2 is a schematic perspective view of the feed roller 10 and the retard roller 20 of the separation mechanism 4. Fig. 3 is an expanded view of expanding a part of the outer peripheral surface 11 of the feed roller 10 into a plane. Fig. 4 is a cross-sectional view taken along line IV-IV of fig. 3, and is a view showing the outer peripheral surface 11 of the feed roller 10 in a cross section orthogonal to the axial direction S1 of the feed roller 10. Fig. 5 is an expanded view of expanding the outer peripheral surface 21 of the retard roller 20 into a plane. Fig. 6 is a cross-sectional view taken along line VI-VI of fig. 5, and shows the outer peripheral surface 21 of the retard roller 20 in a cross section orthogonal to the axial direction S2 of the retard roller 20. Fig. 7 is a cross-sectional view taken along line VII-VII of fig. 5, and is a view showing the outer peripheral surface 21 of the retard roller 20 in a cross-section parallel to the axial direction S2 of the retard roller 20.

Referring to fig. 1, a sheet feeding device 1 is disposed in an image forming apparatus. Examples of such an image forming apparatus include a copier, a printer, a multifunction peripheral, and a facsimile machine.

The sheet feeding device 1 includes a pickup roller 3 disposed above the sheet tray 2 and a separation mechanism 4 adjacent to the pickup roller 3.

The sheet tray 2 can accommodate a plurality of sheets 5. The paper 5 is not limited to paper, and may be other sheet such as a plastic sheet that can be subjected to image formation by the image forming apparatus.

The pickup roller 3 has a structure in which an elastic roller is attached to the outer periphery of the spindle 3a, for example, and is rotationally driven by an electric motor, not shown. When the pickup roller 3 is rotationally driven and the sheet 5 on the sheet tray 2 is fed out from the sheet tray 2 by the rotation of the pickup roller 3, the sheet 5 is fed out to the separation mechanism 4.

The separating mechanism 4 is provided to send out the sheets 5 fed from the pickup roller 3 one by one toward an image forming portion (not shown). The separating mechanism 4 is configured to send out only one sheet 5 when a plurality of sheets 5 are conveyed from the pickup roller.

The separation mechanism 4 has a feed roller 10 and a retard roller 20.

The feed roller 10 is configured to be rotated by an electric motor, not shown, and a driving force for conveying the paper 5 is applied to the feed roller 10 from the electric motor. The feed roller 10 applies the driving force described above to the sheet 5 fed by the pickup roller 3, thereby feeding the sheet 5 toward the image forming portion and rightward in fig. 1. The feed roller 10 is an elastic body roller wound around the outer periphery of the mandrel 6, and the outer peripheral surface of the elastic body roller is the outer peripheral surface 11 of the feed roller 10.

Referring to fig. 2 to 4, a plurality of ribs 13 extending mainly in the axial direction S1 of the feed roller 10 and the axial direction S1 in the circumferential direction C1 are provided on the outer peripheral surface 11 of the feed roller 10 along the circumferential direction C1. In this case, "the ridge 13 extending with the axial direction S1 as the main component" means that the magnitude V1S of the axial component is larger than the magnitude V1C of the circumferential component with respect to the vector V1 connecting one end and the other end of the convex 13 in the longitudinal direction L1, which is the direction in which the convex 13 extends. In other words, it means that the inclination angle θ1 (inferior angle) of the convex 13 with respect to the axial direction S1 is smaller than 45 °. The inclination angle θ1 is preferably 30 ° or less, more preferably 15 ° or less, and particularly preferably zero (parallel to the axial direction S1) as in the present embodiment. That is, in the present embodiment, the convex strip 13 of the feed roller 10 extends parallel to the axial direction S1 of the feed roller 10. In an expanded view in which the outer peripheral surface 11 of the feed roller 10 is expanded into a flat surface, the convex strips 13 extend linearly. In the present embodiment, the feed roller 10 is a knurled roller in which a plurality of convex portions 13 are arranged in the circumferential direction C1. In this way, the convex 13 extends with the axial direction S1 as a main component, and the feed roller 10 as a driving roller can contact the sheet 5 so as to pull out the sheet 5. This can further improve the transmission efficiency of the driving force from the feed roller 10 to the sheet 5.

Referring to fig. 1, 2, 5, and 7, the retard roller 20 is configured to be rotatable in association with the feed roller 10 by applying the driving force described above from the feed roller 10, and is provided with a predetermined rotational resistance in a direction opposite to the rotational direction A2 during the associated rotation. The retard roller 20 is an elastic roller wound around the outer periphery of the spindle 8, and the outer peripheral surface of the elastic roller is the outer peripheral surface 21 of the retard roller 20. The torque limiter 7 imparts the above-described rotational resistance to the retard roller 20. The retard roller 20 may be rotationally driven by an electric motor, not shown, in a direction opposite to the rotational direction A2 via the torque limiter 7, or may be configured so as not to receive the driving force from the electric motor. The outer peripheral surface 21 of the retard roller 20 is in pressure contact with the outer peripheral surface 11 of the feed roller 10.

According to the above configuration, when the feed roller 10 starts to rotate, the retard roller 20 rotates in the rotation direction A2 in association with the feed roller 10. The sheet 5 fed out from the sheet tray 2 by the pickup roller 3 enters between the feed roller 10 and the retard roller 20, and the sheet 5 advances while being pressurized by the feed roller 10 and the retard roller 20. At this time, the retard roller 20 is normally rotated in a direction (rotational direction A2) in which the sheet 5 is fed out by receiving a rotational force from the feed roller 10 via the sheet 5. On the other hand, there is a case where two (plural) sheets 5 are erroneously fed out by the pickup roller 3. In this case, when two sheets 5 enter between the feed roller 10 and the retard roller 20, the retard roller 20 contacts the lower sheet 5 and slides between the upper and lower sheets 5, and therefore the retard roller 20 does not rotate in the rotation direction A2 and does not pass the lower sheet 5. As a result, only the sheet 5 in contact with the feed roller 10 among the plurality of sheets 5 advances.

The retard roller 20 is disposed parallel to the feed roller 10. The outer peripheral surface 21 of the retard roller 20 is provided with a plurality of circumferential ridges 23 extending along the axial direction S2 and having the circumferential direction C2 of the retard roller 20 as a main component. In this case, "the circumferential ridge 23 extending with the circumferential direction C2 as the main component" means that the magnitude V2C of the circumferential component is larger than the magnitude V2S of the axial component with respect to the vector V2 of any part of the circumferential ridge 23 in the longitudinal direction L2, which is the direction in which the circumferential ridge 23 extends. In other words, the inclination angle θ2 (inferior angle) of the circumferential ridge 23 with respect to the circumferential direction C2 is smaller than 45 °. The inclination angle θ2 is preferably 30 ° or less, more preferably 15 ° or less, and particularly preferably zero (parallel to the circumferential direction C2) as in the present embodiment. That is, in the present embodiment, the circumferential ridge 23 of the retard roller 20 extends parallel to the circumferential direction C2 of the retard roller 20. In the present embodiment, the circumferential ridge 23 extends linearly in an expanded view in which the outer peripheral surface 21 of the retard roller 20 is expanded into a flat surface. As described above, the circumferential ridge 23 extends with the circumferential direction C2 as a main component, so that the retard roller 20 serving as a driven roller can support the sheet 5 in a more stable posture, and the sheet 5 is less likely to catch, and can be smoothly conveyed.

In the present embodiment, axial protrusions 24 are provided on the outer peripheral surface of the retard roller 20 in addition to the circumferential protrusions 23. Thus, the retard roller 20 is a roller having a lattice-like convex shape formed on the surface. The axial direction convex strips 24 are convex strips extending mainly in the axial direction S2 of the retard roller 20 and the axial direction S2 of the circumferential direction C2, and are provided in plurality along the circumferential direction C2. In this case, "the axial ridge 24 extending with the axial direction S2 as the main component" means that the magnitude V3S of the axial component is larger than the magnitude V3C of the circumferential component with respect to the vector V3 of any part of the axial ridge 24 in the longitudinal direction L3, which is the direction in which the axial ridge 24 extends. In other words, the inclination angle θ3 (inferior angle) of the axial protrusions 24 with respect to the axial direction S2 is smaller than 45 °. The inclination angle θ3 is preferably 30 ° or less, more preferably 15 ° or less, and particularly preferably zero (parallel to the axial direction S2) as in the present embodiment. That is, in the present embodiment, the axial direction convex strip 24 of the retard roller 20 extends parallel to the axial direction S2 of the retard roller 20. In the present embodiment, the axial protrusions 24 extend linearly in a developed view in which the outer peripheral surface 21 of the retard roller 20 is developed into a flat surface. According to this structure, in a preferred embodiment, the plurality of circumferential ridges 23 and the plurality of axial ridges 24 are arranged in a lattice shape as a whole.

As described above, according to the present embodiment, since the convex strip 13 of the feed roller 10 extends with the axial direction S1 as the main component, the force for reliably conveying the sheet 5 can be applied to the sheet 5 by the convex strip 13. Thereby, the feed roller 10 can apply a sufficient driving force to the sheet 5 for a long period of time. Further, since the circumferential ridge 23 of the retard roller 20 extends with the circumferential direction C2 as a main component, the sheet 5 is smoothly received by the retard roller 20 and allowed to move on the retard roller 20 by the circumferential ridge 23 so that the sheet 5 does not catch. Accordingly, even when the paper feeding device 1 is used for a long period of time, conveyance failure such as paper jam in the paper feeding device 1 can be more reliably suppressed. Further, fine powder such as paper dust can be discharged into the groove 15 between the two ridges 13, 13 of the feed roller 10 and the groove 25 between the two circumferential ridges 23, 23 of the retard roller 20. This can suppress the paper dust from remaining in the nip between the ridge 13 of the feed roller 10 and the circumferential ridge 23 of the retard roller 20. This suppresses a decrease in the friction coefficient between the feed roller 10 and the retard roller 20 even when the paper feeding apparatus 1 is used for a long period of time. As a result, the degree of rotation of the retard roller 20 with the rotation of the feed roller 10 can be kept high for a long period of time. This can more reliably suppress paper jam caused by a decrease in the joint rotatability (joint rotatability) of the feed roller 10 and the retard roller 20.

If a roller having a lattice-shaped contact surface formed on the outer peripheral surface is used as the feed roller, the feed roller is likely to slip with the retard roller 20 when used for a longer period of time than the knurled feed roller 10. In the case of using a roller having a knurled shape such as the feed roller 10 as the retard roller, the retard roller is more likely to catch on the paper 5 than the feed roller 10 described above, and a jam is likely to occur. In this way, by disposing the knurled feed roller 10 and disposing the retard roller 20 including the circumferential convex strip 23 having the circumferential direction C2 as the main component on the opposite side of the feed roller 10, which is unique to the present application, it is possible to suppress the conveyance failure of the paper 5 such as a jam for a long period of time and more reliably.

Further, according to the present embodiment, the ridge 13 of the feed roller 10 extends along the axial direction S1 of the feed roller 10, the circumferential ridge 23 of the retard roller 20 extends along the circumferential direction C2 of the retard roller 20, and the axial ridge 24 of the retard roller 20 extends along the axial direction S2 of the retard roller 20. According to this configuration, high transmission efficiency of the driving force from the feed roller 10 to the sheet 5 and smoother conveyance of the sheet 5 on the retard roller 20 can be achieved in a balanced manner.

Further, according to the present embodiment, the plurality of circumferential ridges 23 and the plurality of axial ridges 24 of the retard roller 20 are arranged in a lattice shape as a whole. According to this configuration, the sheet 5 can be placed on the retard roller 20 receiving the self weight of the sheet 5 with a more uniform surface pressure, and the fine powder generated with long-term use can be reliably accumulated in the groove 25 between the ridges 23 and 24. This can maintain smooth conveyance of the sheet 5 by the feed roller 10 and the retard roller 20 for a long period of time.

Next, a more preferable mode of the feed roller 10 and the retard roller 20 will be described.

More preferable structure of feed roller

Referring to fig. 2 to 4, as a material of the feed roller 10, for example, polyurethane, EPDM, and other synthetic rubbers, which are one type of synthetic rubber, can be exemplified. The material of the feed roller 10 may be other than synthetic rubber, which has elasticity to return to its original shape immediately after being deformed by a relatively small external force.

The hardness of the feed roller 10 is not particularly limited, and is preferably 30 to 70 in durometer a, for example. If the A hardness is less than the lower limit, the abrasion loss of the rubber is large, and the desired shape cannot be maintained. On the other hand, if the a hardness exceeds the upper limit, the grip amount is small, and the friction coefficient is too low, so that 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 durometer a hardness is K6253 according to JIS (japanese industrial standard): 2006.

The feed roller 10 is preferably provided with a ridge 13 having the axial direction S1 as a main component, but is preferably not provided with a ridge having the circumferential direction C1 as a main component. This is because, if the protruding strip having the circumferential direction C1 as the main component is provided, slippage is likely to occur between the protruding strip and the paper sheet when the separating mechanism 4 is used for a long period of time. However, the feed roller 10 may be further provided with a convex strip having the circumferential direction C1 as a main component. That is, the feed roller 10 may be further provided with a circumferential protruding strip extending at an angle exceeding 45 ° with respect to the axial direction S1 and capable of contacting the sheet 5. Even when such a circumferential ridge is provided, it is preferable that the circumferential ridge be of a small length. The "minute" in this case can be exemplified by 10% or less and 5% or less of the total length of the respective ridges 13 in the longitudinal direction L1 of the feed roller 10.

The outer peripheral surface 11 of the feed roller 10 has a cylindrical portion 12 and a convex strip 13 protruding from the cylindrical portion 12. The cylindrical portion 12 is, for example, cylindrical. The cylindrical portion 12 is configured so as not to contact the paper 5 by making the height of the protruding strip 13 sufficiently high.

Preferably, the ridges 13 are provided at equal pitches in the circumferential direction C1 of the feed roller 10. The arrangement pitch P1 of the convex strips 13 in the circumferential direction C1 is preferably 0.9mm to 1.3mm. If the arrangement pitch P1 is smaller than the lower limit, the volume of the groove 15 is small, and the paper dust adhering to the paper surface cannot be discharged effectively. On the other hand, if the arrangement pitch P1 exceeds the upper limit, the frequency of contact between the feed roller 10 and the paper 5 decreases during rotation of the feed roller 10, and slippage tends to occur between the feed roller 10 and the paper 5. The lower limit of the arrangement pitch P1 of the convex strips 13 is preferably 0.95mm, and the upper limit of the arrangement pitch P1 is preferably 1.1mm. The ridges 13 may be arranged at different pitches in the circumferential direction C1.

When viewed from the axial direction S1, each of the convex strips 13 is preferably formed in a trapezoidal shape, for example. If the convex strip 13 is shaped as described above, the driving force can be transmitted intensively from the tip of the convex strip 13 to the paper 5, and the transmission efficiency of the driving force can be improved. The shape of the ridge 13 as seen in the axial direction S1 may be triangular, quadrangular, involute, cycloid, or other.

Preferably, each ridge 13 is formed over the entire region of the outer peripheral surface 11 of the feed roller 10 in the axial direction S1. However, the ridge portion may be formed intermittently in the axial direction S1 in one ridge 13.

The height h1 of the ridge 13 is preferably 0.3mm to 0.7mm from the cylindrical portion 12 of the ridge 13 in the radial direction of the feed roller 10. If the height h1 is smaller than the lower limit, the volume of the groove 15 between the ridges 13, 13 is small, and the paper dust adhering to the paper surface cannot be discharged effectively. On the other hand, if the height h1 exceeds the upper limit, the abrasion amount of the convex strip 13 is large when the sheet 5 repeatedly passes through the sheet feeding device 1, and the required shape cannot be maintained, and the transmission efficiency of the driving force from the feed roller 10 to the sheet 5 is lowered. The lower limit of the height h1 of the ridge 13 is preferably 0.4mm, and the upper limit of the height h1 is preferably 0.6mm.

Preferably, the width w1 of the tip of the ridge 13 in the circumferential direction C1 is 0.2mm to 0.5mm. The width w1 is, for example, the width of a portion where the paper 5 contacts when the paper feeding device 4 is new. If the width w1 is smaller than the lower limit, the convex strip 13 becomes too thin, the contact area between the paper 5 and the convex strip 13 becomes small, and the friction (conveying force) decreases. On the other hand, if the width w1 exceeds the upper limit, the circumferential length of the groove 15 between the adjacent ridges 13 cannot be sufficiently ensured, and it is difficult to discharge fine powder into the groove 15, and the friction (conveying force) decreases. The lower limit of the width w1 of the tip of the ridge 13 is preferably 0.3mm, and the upper limit of the width w1 is preferably 0.4mm.

Preferably, the inclination angle θx of the ridge 13 when viewed from the axial direction S1 is 36 ° or less (including zero). The inclination angle θx is an angle formed by a radial straight line extending from the center of the feed roller 10 to the side surface (end surface in the circumferential direction C1) of the ridge 13 and the side surface. If the inclination angle θx is smaller than 36 °, the groove 15 can be made to have a sufficient depth, and therefore, fine powder can be easily stored in the groove 15. This can suppress the decrease in the friction coefficient of the rollers 10 and 20 due to the fine powder. The inclination angle θx is preferably 20 ° or less (including zero).

A groove 15 is provided between two ridges 13 in the circumferential direction C1. The groove 15 is provided as a space for the fine powder to fall. This can suppress a decrease in the friction coefficient of the protruding strip 13, and thus cannot sufficiently obtain the friction force for conveying the paper 5.

More preferred structure of retard roller

Referring to fig. 2 and 5 to 7, the same material as that of the feed roller 10 can be exemplified as the material of the retard roller 20.

The hardness of the retard roller 20 is not particularly limited, and is preferably 30 to 70 in durometer a, for example. If the A hardness is less than the lower limit, the abrasion loss of the rubber is large, and the desired shape cannot be maintained. On the other hand, if the a hardness exceeds the upper limit, the grip amount is small, and the friction coefficient is too low, so that the required conveying force may not be ensured. The lower limit of the hardness of the retard roller 20 is preferably 40, and the upper limit of the a hardness of the retard roller 20 is preferably 60.

The outer peripheral surface 21 of the retard roller 20 has a cylindrical portion 22, and circumferential ridges 23 and axial ridges 24 protruding from the cylindrical portion 22. The cylindrical portion 22 is, for example, cylindrical. The cylindrical portion 22 is configured so as not to contact the paper 5 by making the heights of the protruding strips 23, 24 sufficiently high.

The circumferential ridges 23 may be arranged at a different pitch in the axial direction S2 of the retard roller 20, but it is preferable that the circumferential ridges 23 be arranged at a same pitch in the axial direction S2 of the retard roller 20. With such an equal pitch arrangement, the posture of the sheet 5 on the retard roller 20 in the axial direction S2 can be stabilized more. The arrangement pitch P2 of the circumferential ridge 23 in the axial direction S2 is preferably 1.0mm to 1.5mm. A more preferable range of the arrangement pitch P2 is 1.1mm to 1.4mm. If the arrangement pitch P2 is smaller than the lower limit, the capacity of the groove 25 for accommodating the fine powder cannot be sufficiently ensured, and it is difficult to discharge the fine powder into the groove 25 during long-term use. On the other hand, if the arrangement pitch P2 exceeds the upper limit, the span in which the retard roller 20 and the sheet 5 are in contact in the axial direction S2 is large, the wrinkles of the sheet 5 in the axial direction S2 are large, the contact pressure between the convex strip 13 of the feed roller 10 and the sheet 5 is unstable, and the transmission efficiency of the driving force from the feed roller 10 to the sheet 5 is reduced.

In a cross section orthogonal to the circumferential direction C2 (fig. 7), each circumferential ridge 23 is preferably formed in a rounded curve shape (a curved shape protruding outward in the radial direction of the retard roller 20) formed as a wavy curved surface. If the circumferential ridge 23 has such a shape, the area for receiving the sheet 5 can be easily secured sufficiently at the tip of the circumferential ridge 23, and the sheet 5 can be smoothly fed out. In the cross section orthogonal to the circumferential direction C2, each circumferential ridge 23 may have a rectangular shape, a triangular shape, an involute tooth shape, a cycloid tooth shape, or other shapes.

Preferably, each circumferential ridge 23 is formed over the entire area of the outer peripheral surface 21 of the retard roller 20 in the circumferential direction C2. However, in one circumferential ridge 23, the ridge portion may be intermittently formed in the circumferential direction C2.

The height h2 of the circumferential ridge 23 is preferably 0.15mm to 0.4mm from the cylindrical portion 22 of the circumferential ridge 23 in the radial direction of the retard roller 20. If the height h2 is smaller than the lower limit, the volume of the groove 25 is small, and the paper dust adhering to the surface of the paper cannot be discharged effectively. On the other hand, if the height h2 exceeds the upper limit, the depth of the groove 25 is too deep, and it is difficult to perform demolding at the time of manufacturing the retard roller 20.

Preferably, the width w2 of the base portion of the circumferential ridge 23 in the axial direction S2 is 0.8mm to 1.0mm. The width w2 is, for example, the width of a portion where the paper 5 contacts when the paper feeding device 4 is new. If the width w2 is smaller than the lower limit, the abrasion amount of the ridge 23 is large, the desired shape cannot be maintained, the contact pressure between the ridge 13 of the feed roller 10 and the paper 5 is reduced, and the transmission efficiency of the driving force is reduced. On the other hand, if the width w2 exceeds the upper limit, the axial length of the groove 25 between the adjacent circumferential ridges 23 cannot be sufficiently ensured, and the capacity for accumulating fine powder is small. The boundary between the circumferential ridge 23 and the groove 25 corresponds to the boundary between the upwardly convex shape portion and the downwardly convex shape portion in the cross section shown in fig. 7.

The axial protrusions 24 may be arranged at a different pitch in the circumferential direction C2 of the retard roller 20, but are preferably arranged at a different pitch. Preferably, the arrangement pitch P3 of the axial protrusions 24 in the circumferential direction C2 is 1.0mm to 1.5mm. A more preferable range of the arrangement pitch P3 is 1.1mm to 1.4mm. If the arrangement pitch P3 is smaller than the lower limit, the capacity of the groove 25 for accommodating the fine powder cannot be sufficiently ensured, and it is difficult to discharge the fine powder into the groove 25 during long-term use. On the other hand, if the arrangement pitch P3 exceeds the upper limit, the frequency of contact between the retard roller 20 and the sheet 5 decreases during rotation of the retard roller 20, and the wrinkles of the sheet 5 in the conveying direction of the sheet 5 become large, so that it is difficult to smoothly feed out the sheet 5.

When viewed from the axial direction S2, each of the axial protrusions 24 is preferably formed in a rounded curve shape (curved shape protruding radially outward of the retard roller 20) formed as a wavy curved surface. If the axial protruding strip 24 has such a shape, the area for receiving the sheet 5 can be easily secured sufficiently at the tip of the axial protruding strip 24, and the sheet 5 can be smoothly fed out. The axial ridge 24 may have a rectangular shape, a triangular shape, an involute tooth shape, a cycloid tooth shape, or other shapes when viewed from the axial direction S1.

Preferably, each axial protrusion 24 is formed over the entire area of the outer peripheral surface 21 of the retard roller 20 in the axial direction S2. However, in one axial ridge 24, the ridge portion may be intermittently formed in the axial direction S2.

Preferably, the height h3 of the axial ridge 24 is the same as the height h2 of the circumferential ridge 23.

Preferably, the width w3 of the base portion of the axial ridge 24 in the circumferential direction C2 is 0.8mm to 1.0mm. The width w3 is, for example, the width of a portion where the paper 5 contacts when the paper feeding device 4 is new. If the width w3 is smaller than the lower limit, the contact area between the axial direction convex strip 24 and the paper 5 is small, and the friction force (conveying force) is reduced. On the other hand, if the width w3 exceeds the upper limit, the circumferential length of the groove 25 between the adjacent axial ridges 24 cannot be sufficiently ensured, the capacity for accumulating fine powder is small, and it is difficult to discharge the fine powder into the groove 15, and the friction force (conveying force) of the outer peripheral surface 21 is reduced. The boundary between the circumferential ridge 24 and the groove 25 corresponds to the boundary between the upwardly convex shape portion and the downwardly convex shape portion in the cross section shown in fig. 6.

The groove 25 is formed at a portion surrounded by the circumferential ridge 23 and the axial ridge 24 arranged in a lattice shape. The groove 25 is provided as a space for the fine powder to fall. This can suppress the friction coefficient of the outer peripheral surface 21 of the retard roller 20 from decreasing and excessively reduce the friction force between the sheet 5 and the retard roller 20. The groove portions 25 are preferably regularly arranged in the axial direction S2, preferably regularly arranged in the circumferential direction C2, more preferably regularly arranged in both the axial direction S2 and the circumferential direction C2. In this case, "regular" may mean that the grooves 25 are arranged at equal pitches, or that the grooves 25 are arranged at a plurality of pitches as a group, and a plurality of the groups are repeated.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments and modifications, and various modifications are possible within the scope of the claims.

(1) In the above embodiment, the case where the convex strip 13 of the feed roller 10 is parallel to the axial direction S1 is illustrated. As an example of the above embodiment, the inclination angle θ1 of the ridge 13 is smaller than 45 °. When the inclination angle θ1 is 30 °, the convex strip 13 has a shape shown in fig. 8, for example. Fig. 8 is an expanded view for explaining a main portion of the convex strip 13 in the modification of the feed roller 10.

(2) In the above embodiment, the description has been made taking, as an example, the case where the circumferential ridge 23 of the retard roller 20 extends along the circumferential direction C2 and the axial ridge 24 extends along the axial direction S2. As an example of the above embodiment, the inclination angles θ2 and θ3 of the ridges 23 and 24 are smaller than 45 ° respectively. In the case where the inclination angles θ2 and θ3 are 30 °, for example, the shape shown in fig. 9 is used. Fig. 9 is an expanded view for explaining the main portions of the circumferential ridge 23 and the axial ridge 24 in the modification of the retard roller 20. The inclination angles θ2 and θ3 may be different from each other.

Examples

As an image forming apparatus, SP8400 manufactured by riken corporation was prepared. The paper feeding device of the image forming device comprises a feed roller rotationally driven by a driving motor and a delay roller connected with a supporting shaft through a torque limiter.

The following three types of rollers were prepared as rollers used as the feed roller and/or the retard roller.

1. Grinding roller

2. Lattice roller

3. Knurling roller

Common structure of rolls

The diameter of the outer diameter is 20mm, the diameter of the inner diameter is 12.4mm, and the axial length is 24mm. Further, the hardness was A50 in terms of the durometer hardness of JIS.

< 1. Structure peculiar to grinding roller >

The polishing roller is a roller in which polishing marks are formed by polishing the outer peripheral surface of the roller with a polishing wheel. Other specifications are shown below.

Material quality: EPDM (ethylene-propylene-diene monomer rubber)

< 2 > Structure peculiar to lattice roll >

As the lattice roller, a roller used as the retard roller 20 is prepared. The specification of the lattice roll is as follows.

Material quality: EPDM (ethylene-propylene-diene monomer rubber)

Arrangement pitch P2 of circumferential ridge 23: 1.3mm

Cross-sectional shape of the circumferential ridge 23: rounded curve shape protruding radially outward of the roller

Height h2 of circumferential ridge 23: 0.20mm

Width w2 of base of circumferential ridge 23: 0.9mm

Inclination angle θ2 of circumferential ridge 23: 0 degree (degree)

Arrangement pitch P3 of axial ridges 24: 1.3mm

Shape of axial rib 24: rounded curve shape protruding radially outward of the roller

Height h3 of axial bead 24: 0.20mm

Width w3 of base of axial bead 24: 0.9mm

Inclination angle θ3 of axial ridge 24: 0 degree (degree)

< 3. Structure peculiar to knurling roller >)

As the knurling roller, a roller used as the feed roller 10 is prepared. The specification of the knurling roller is as follows.

Material quality: EPDM (ethylene-propylene-diene monomer rubber)

Arrangement pitch P1 of the convex strips 13: 1.0mm

Shape of the ridge 13: trapezoid shape

Height h1 of ridge 13: 0.5mm

Width w1 of tip of ridge 13: 0.3mm

Inclination angle θ1 of ridge 13: 0 degree (degree)

Test method

Comparative examples 1 to 4 and example 1 were prepared by setting the feed roller and the retard roller of the paper feeding apparatus to the combination of the rollers shown in table 1. Further, with the image forming apparatus, each time a predetermined number of sheets shown in table 1 are fed by the sheet feeding apparatus, the feed roller and the retard roller are detached from the image forming apparatus, and are mounted on the evaluation apparatus shown in fig. 10. The paper is paper (plain paper) manufactured by riken corporation. Fig. 10 is a schematic diagram of the evaluation apparatus.

The evaluation device shown in fig. 10 includes: an electric motor; a feed roller support shaft to which an output shaft of the electric motor is attached and to which a feed roller is attached; a retard roller support shaft embedded in the retard roller; and a torque limiter that is attached to the retard roller support shaft and that imparts a predetermined rotational resistance to the retard roller. The feed roller mounted on the evaluation device was pressed against the retard roller with a load of 400 gf. The torque limiter is configured to generate a resistance torque of 400gf cm when the retard roller and the feed roller rotate in association with each other.

Then, the feeding roller and the retard roller when the feeding roller is rotated by driving the electric motor in the evaluation device are imaged by the camera, whereby the case where the retard roller is rotated in association (rotated in association) is imaged. Next, by observing the video, the joint rotation (%) as a proportion of the joint rotation of the retard roller with respect to the rotation of the feed roller is calculated. The rotation (%) is defined by the following formula.

The associated rotation (%) = (the number of seconds taken by the feed roller to make one rotation/the number of seconds taken by the retard roller to make one rotation) ×100

Table 1 shows the number n of sheets fed by the sheet feeder (n=0, 1 ten thousand, 2 ten thousand, 3 ten thousand, 5 ten thousand, 7 ten thousand, 10 ten thousand, 15 ten thousand, 20 ten thousand) and the associated rotation (%) when the n sheets are fed.

TABLE 1

In this test, when the associated rotation is 80% or more at the time when the number of sheets fed n=7ten thousand, it is determined as o. Further, when the conjoint rotatability is 40% or more and less than 80% at the time of n=7ten thousand, it is determined as Δ. When the joint rotatability was less than 40% at the time of n=7ten thousand (including the case where the evaluation was suspended), it was determined as x. The results are shown in table 1.

In addition, if the associated rotation is about 60%, paper jam is unlikely to occur in the paper feeding apparatus, but the paper conveyance performance tends to be lowered, and therefore, the criterion of Δ is set as described above. On the other hand, if the associated rotatability is less than 40%, the sheet feeding apparatus is in a shape in which jam is likely to occur, and therefore, the x judgment criterion is set as described above.

In comparative example 1, the wear rate of the contact surfaces of the feed roller and the retard roller and the retention rate of fine powder were high, and at the time of feeding 3 ten thousand sheets, the rotation of the feed roller and the retard roller was less than 40%, and paper jam was often caused. Therefore, the test was stopped when 3 ten thousand sheets were fed, and evaluated as x. In comparative example 2, the progress of the retention of fine powder in the feed roller was fast, and the rotation of the feed roller was less than 70% at the time of feeding 7 ten thousand sheets, and thus the test was stopped and evaluated as Δ. With comparative example 3, the progress of the friction force decrease in the feed roller was fast, and at the timing of feeding 7 ten thousand sheets, the accompanying rotation was less than 40%, and paper jam was often occurred. Therefore, the test was stopped when 7 ten thousand sheets were fed, and evaluated as x. In comparative example 4, the progress of the retention of fine powder in the retard roller was fast, and the rotation was far below 70% at the time of feeding 10 ten thousand sheets, and therefore, the test was stopped and evaluated as Δ.

In addition, although not described as a comparative example, in the case of the comparative example in which the retard roller uses the knurling roller, since it is expected that the paper is caught in the groove of the knurling roller and the possibility of occurrence of paper jam is high, no test is performed.

On the other hand, in embodiment 1, the ridges of the feed roller as the knurled roller can apply a sufficient driving force to the sheet for a long period of time, and the circumferential ridges of the retard roller as the lattice roller can smoothly receive the sheet by the retard roller and can move on the retard roller so that the sheet does not catch. Thus, even when paper is fed for 20 ten thousand sheets, rotation-related properties exceeding 80% can be ensured, and paper jam does not occur. As described above, the effect of being able to suppress conveyance failure such as paper jam for a long period of time was confirmed for the embodiment.

Industrial applicability

The present invention can be used as a paper feeding device.

Description of the reference numerals

1. A paper feeding device; 5. paper sheets; 10. a feed roller; 11. an outer peripheral surface of the feed roller; 13. a convex strip of the feed roller; 20. a retard roller; 21. an outer peripheral surface of the retard roller; 23. circumferential ridges (ridges of the retard roller); 24. axial ribs (ribs of retard roller); a2, rotating direction; c1, circumferential direction of the feed roller; c2, delaying the circumference of the roller; s1, axially feeding a roller; s2, delaying the axial direction of the roller.

Claims

1. A paper feeding device, wherein,

the paper feeding device comprises:

a feed roller to which a driving force for conveying the sheet is applied; and

2. The paper feeding apparatus according to claim 1, wherein,

the ribs of the feed roller extend in the axial direction of the feed roller,

3. The sheet feeding device according to claim 1 or 2, wherein,