JP2006027793A - Torque limiter, retard roll, paper feeding device, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a torque limiter having high torque stability and provided with a fixed member and a movable member to be fitted in each other in a recessed and a projecting parts thereof in the axial direction, to provide a retard roll capable of realizing reduction of costs, to provide a paper feeding device, and to provide an image forming device using the same. <P>SOLUTION: The torque limiter 78 has a fixed member 106 supported with regulation of rotation thereof and a movable member 108 supported freely to rotate. The fixed member 106 having a circular projecting part 120 is fitted in a circular recessed part 114 formed in the movable member 108 for sliding in the axial direction. With this structure, since area of a sliding fitting part 116 can be reduced and influence of pushing force energized in the radial direction can be restricted, instability of torque due to friction and bend of the sliding surface can be prevented. Shape of the fixed member 106 made of a metal material is simple and miniaturized to realize reduction of costs. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a torque limiter, a retard roll having the torque limiter, a sheet feeding device having the retard roll, and an image forming apparatus having the sheet feeding device.

  2. Description of the Related Art Image forming apparatuses such as copying machines, printers, and facsimiles include a paper feeding device that supplies paper to an image forming unit. The paper feeding device needs to pick up the paper loaded in a paper feeding cassette or the like one by one and supply it to the image forming unit. As one of conventional paper-making mechanisms, a mechanism that uses a retard roll to face a feed roll is known. A torque limiter using a coil spring is used for the retard roll, and this torque limiter is provided with a fixed drum portion and a movable drum portion around the fixed drum portion (for example, Patent Document 1).

JP-A-8-2726

  In the conventional example described above, the support portion is integrally formed with the fixed drum portion, and the support portion is configured to receive the urging force of the pressure spring. When metal is used for the fixed drum portion, the cost increases. Further, when resin is used for the fixed drum, when the total length is long and the diameter is small, the fixed drum may bend due to insufficient strength, which may cause abnormal noise, wear, torque instability, or the like.

  The present invention relates to a torque limiter having high rigidity and torque stability and realizing cost reduction, a retard roll having the torque limiter, a sheet feeding device having the retard roll, and an image forming apparatus having the sheet feeding device. It is intended to provide.

  In order to achieve the above-mentioned goal, the first feature of the present invention is that a first member having a cylindrical inner wall and a cylindrical outer wall are provided, and this outer wall is the inner wall of the first member. When the second member disposed on the outer side, the inner wall of the first member and the outer wall of the second member are disposed, and the first member and the second member rotate relatively An elastic member that changes the friction between the first member and the second member according to the torque of the first member and the axial direction of either the first member or the second member. A circular recess is formed on the other side, and a circular protrusion protruding in the axial direction is formed on the other side. The torque limiter is formed by fitting the recess and the protrusion in the axial direction. Therefore, since the sliding surfaces of the concave portion and the convex portion are different from the direction in which the urging means urges, the influence of the pressing force can be mitigated.

  The second feature of the present invention is that it has a movable member having a cylindrical inner wall and a cylindrical roll surface, and a cylindrical outer wall, and the outer wall is disposed inside the inner wall of the movable member. A fixed member, and an elastic member that changes friction between the fixed member and the movable member according to a torque when the movable member rotates with respect to the fixed member, and the movable member or the In one of the fixing members, a circular concave portion that is recessed in the axial direction is formed, and on the other side, a circular convex portion that protrudes in the axial direction is formed, and the retard roll is formed by fitting the concave portion and the convex portion in the axial direction. is there.

  Preferably, the retard roll has a bearing member that rotatably supports the movable member.

  Preferably, the retard roll has a shaft portion protruding in the axial direction on the movable member, and is supported by fitting a bearing member on the outside of the shaft portion.

  Preferably, the retard roll has a shaft portion that is recessed in the axial direction in the movable member, and is supported by fitting a bearing member inside the shaft portion.

  The third feature of the present invention is that a feed roll supported rotatably, a retard roll provided opposite to the feed roll, and an urging force for biasing the retard roll toward the feed roll. The retard roll includes a movable member having a cylindrical inner wall and a cylindrical roll surface that contacts the feed roll, and a cylindrical outer wall, and the outer wall is formed on the movable member. A fixed member disposed inside, and an elastic member that changes friction between the fixed member and the movable member according to a torque when the movable member rotates with respect to the fixed member, The movable member has a circular concave portion that is recessed in the axial direction, and the fixed member is formed with a circular convex portion that protrudes in the axial direction, and the concave portion and the convex portion are fitted in the axial direction.

  Preferably, the retard roll further includes a bearing member that rotatably supports the movable member, and the urging means includes a pressing spring that presses the bearing member by the pressing spring.

  The present invention includes an image forming apparatus having the above-described paper feeding device.

  According to the present invention, a circular concave portion that is recessed in the axial direction is formed on one of the fixed member or the movable member of the torque limiter, and a convex portion that protrudes in the axial direction is formed on the other side. By fitting in the direction, high rigidity and torque stability and cost reduction can be realized.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an outline of an image forming apparatus 10 according to an embodiment of the present invention. The image forming apparatus 10 includes an image forming apparatus main body 12, an image forming unit 14 is mounted in the image forming apparatus main body 12, and a discharge unit 16 is provided on the upper portion of the image forming apparatus main body 12. A paper feeding device 18 is provided below the image forming apparatus main body 12. The sheet feeding device 18 includes a sheet feeding cassette 20 that stores a bundle of sheets and a sheet feeding main body 22. The paper feed main body 22 includes a feed roll 24 and a retard roll 26 that face each other. The sheet main body unit 22 supplies the uppermost sheet in the sheet bundle stored in the sheet feeding cassette 20.

  The discharge unit 16 includes an inclined portion 28 that is rotatable with respect to the image forming apparatus main body 12. The inclined portion 28 has a low discharge port portion and is inclined so as to gradually increase toward the front direction (right direction in FIG. 1), with the discharge port portion as a lower end and a higher tip as an upper end. . The inclined portion 28 is supported by the image forming apparatus main body 12 so as to be rotatable about the lower end. As shown by a two-dot chain line in FIG. 1, when the inclined portion 28 is rotated upward and opened, an opening portion 30 is formed, and a process cartridge 32 (to be described later) can be attached and detached through the opening portion 30. .

  The image forming means 14 is of, for example, an electrophotographic system, and includes an image carrier 34 made of a photosensitive member, a charging device 36 made of, for example, a charging roll for uniformly charging the image carrier 34, and charged by the charging device 36. An optical writing device 38 for writing a latent image on the image carrier 34 by light, a developing device 40 for visualizing the latent image of the image carrier 34 formed by the optical writing device 38 with a developer, and the developing device For example, a transfer device 42 composed of, for example, a transfer roll for transferring the developer image by the paper 40 to the paper, a cleaning device 44 composed of, for example, a blade for cleaning the developer remaining on the image carrier 34, and the paper transferred by the transfer device 42 For example, a fixing device 46 composed of a pressure roll and a heating roll. The optical writing device 38 is composed of, for example, an optical scanning type laser exposure device, and is disposed near the front surface (right side surface in FIG. 1) of the image forming apparatus main body 12 in parallel with the paper feed cassette 20 of the paper feed device 18. To expose. Further, the developing device 40 includes a developing roll 48 that faces the image carrier 34.

  The process cartridge 32 is obtained by integrating an image carrier 34, a charging device 36, a developing device 40, and a cleaning device 44. The process cartridge 32 is disposed immediately below the inclined portion 28 of the discharge portion 16 and is attached and detached through the opening portion 30 formed when the inclined portion 28 is opened as described above.

  In the image forming apparatus main body 12, for example, a resist roll 50 is disposed on the upstream side (lower side in FIG. 1) of the transfer device 42. The sheet conveyed from the sheet feeding cassette 20 of the sheet feeding device 18 to the conveying path 52 is temporarily stopped by the registration roll 50 and sent to the image forming unit 14 at a predetermined timing to form an image. It is discharged to the discharge unit 16.

  However, in the case of duplex printing, it is returned to the reverse path. That is, the front side of the discharge roll 54 is divided into two forks, and a switching claw 56 is provided at the divided portion, and an inversion path 58 is formed to return from the divided portion to the registration roll 50. The reversing path 58 is provided with transport rolls 60a to 60c. In the case of double-sided printing, the switching claw 56 is switched to the side that opens the reversing path 58 and the discharge roll 54 is in front of the rear end of the sheet. Thus, the discharge roll 54 is reversed, the paper is guided to the reverse path 58, and is discharged to the discharge unit 16 through the resist roll 50, the transfer device 42 and the image carrier 34, and the fixing device 46.

In FIG. 2, details of the paper feed main body 22 are shown.
The paper feed main body 22 includes a feed roll 24 supported by the image forming apparatus main body 12, bearing members 62 and 64 (described later) disposed in the paper feed cassette 20, and a retard roll 26 supported by the bearing members 62 and 64. And a pressing spring 66 as urging means.
The feed roll 24 includes a half-moon roll 68, ring-shaped rollers 70a and 70b, and roller support members 72a and 72b that support the rollers 70a and 70b so as to be rotatable. The shaft 74 is attached.
The retard roll 26 and the feed roll 24 are arranged to face each other, the rollers 70 a and 70 b of the feed roll 24 are always in contact with the retard roll 26, and the half-moon roll 68 is in intermittent contact with the retard roll 26.

In FIG. 3, details of the retard roll 26 are shown.
The retard roll 26 has a torque limiter 78 described later, and a friction member 82 is press-fitted into a roll surface (outer peripheral surface) 80 of the torque limiter 78. The friction member 82 is made of an elastic body such as rubber. A fixed shaft portion 84 and a movable shaft portion 86, which will be described later, are formed on both side surfaces of the retard roll 26 so as to protrude in the axial direction.

A fixed bearing member 62 and a movable bearing member 64 are fitted to the fixed shaft portion 84 and the movable shaft portion 86, and the retard roll 26 is supported by the fixed bearing member 62 and the movable bearing member 64. That is, the fixed shaft portion 84 has a cylindrical shape and is a hollow shaft with a hollow inside, and the fixed bearing member 62 is provided with a protruding portion 88 having a columnar shape. The outer peripheral surface of the protruding portion 88 of the fixed bearing member 62 is inscribed and fitted to the inner peripheral surface of the fixed shaft portion 84. In addition, a plurality of radially projecting key portions 92 are formed in a part of the projecting portion 88 and engaged with a key groove portion 94 provided in the fixed shaft portion 84 to rotate the fixed shaft portion 84. It is regulated.
On the other hand, the movable shaft portion 86 has a columnar projecting shape, and a corresponding bearing portion 90 penetrating in a circular shape is formed in the movable bearing member 64. The movable shaft 86 is rotatably supported with the bearing portion 90 of the movable bearing member 64 inscribed on the outer peripheral surface thereof.

A retard roll storage portion 96 is formed in the vicinity of the back end of the paper feed cassette 20, and a chute (guide member) 98 is provided so as to surround the retard roll storage portion 96. Further, bearing member mounting portions 100, 100 are formed on both side surfaces of the retard roll storage portion 96. Further, the bearing member mounting portion 100 is formed with engaging portions 102 and 102. On the other hand, engagement grooves 104 and 104 are formed on both side surfaces of the fixed bearing member 62 and the movable bearing member 64 so as to engage with the engagement portion 102. The fixed bearing member 62 and the movable bearing member 64 are disposed in the bearing member mounting portions 100 and 100, and the movement of the bearing members 62 and 64 in the axial direction is restricted by the engagement of the engagement groove 104 and the tendency portion 102. ing.
Further, a pressing spring 66 is disposed vertically on the lower surface of the fixed bearing member 62 and the movable bearing member 64, and the retard roll 26 is fed by the pressing spring 66 via the fixed bearing member 62 and the movable bearing member 64. It is biased toward the roll 24. Since the pressing force of the pressing spring 66 acts on the lower surfaces of the fixed bearing member 62 and the movable bearing member 64 from the vertical direction, the inclination of the retard roll 26 in the axial direction can be suppressed.

  In this way, the retard roll 26 is disposed in the retard roll storage portion 96 of the paper feed cassette 20 and can be easily assembled at a position where it abuts on the feed roll 24.

4 and 5 show details of the torque limiter 78. FIG.
The torque limiter 78 includes a fixed member 106, a movable member 108, an elastic member such as a coil spring 110, and a lid member 112. The fixed member 106 is made of a metal material such as stainless steel, and the movable member 108 is made of a resin material such as plastic.
The movable member 108 has a cylindrical roll surface 80 on the outer periphery, a cylindrical concave portion 114 that is recessed in the axial direction is formed inside, and a circular fitting portion 116 that is recessed in the axial direction further inside. In addition, a hollow portion 118 having a smaller diameter than the fitting portion 116 is formed inside. The cavity 118 can be freely changed in shape and size depending on the magnitude of the pressing force urged by the torque limiter 78, and the movable member 108 can be reinforced in some cases.

  The fixed member 106 has a cylindrical shape, and includes the above-described fixed shaft portion 84 and a convex portion 120 that has the same diameter as the fixed shaft portion 84 and protrudes from the movable member 108. Further, the convex portion 120 has a friction portion 122 on the outer peripheral surface.

  The coil spring 110 is disposed between the inner peripheral surface of the concave portion 114 of the movable member 108 and the outer peripheral surface of the convex portion 120 of the fixed member 106. At this time, the coil spring 110 is elastically wound around the friction portion 122 of the fixed member 106, and one end of the coil spring 110 is restricted in movement in the rotational direction by a restriction portion 124 provided on the movable member 108. The coil spring 110 rotates together with the movable member 108 by the restriction of the restriction part 124, and generates torque by the frictional force with the friction part 122 of the fixed member 106.

  The convex portion 120 of the fixed member 106 is fitted to the fitting portion 116, and movement in the radial direction and the axial direction is restricted with respect to the movable member 108. Further, the fitting portion 116 serves as a sliding surface between the fixed member 106 and the movable member 108.

The lid member 112 is formed in a ring shape, is fitted into the lid receiving portion 126 of the movable member 108, and restricts the movement of the coil spring 110 in the axial direction. Further, the inner diameter of the lid member 112 is formed so as not to contact the outer periphery of the fixed member 106.
The lid member 112 may be integrally formed with the fixing member 106.
Further, the rotation of the movable member 108 may be restricted by rotating the fixed member 106.
Further, a concave portion may be formed on the fixed member 106 and a convex portion may be formed on the movable member 108 and fitted.

Next, the operation of the above embodiment will be described.
When the feed roll 24 rotates clockwise from the position shown in FIG. 2, the uppermost sheet stored in the sheet feed cassette 20 is picked up and guided to the nip portion 76 between the feed roll 24 and the retard roll 26.

  As the feed roll 24 rotates, the contacting retard roll 26 rotates counterclockwise. In the rotating retard roll 26, the coil spring 110 restricted by the movable member 108 and the restricting portion 124 rotates, but the fixed member 106 is restricted by the fixed bearing member 62. The convex portion 120 of the fixed member 106 that stops and the concave portion 114 of the rotating movable member 108 abut and slide at the fitting portion 116.

  At this time, a friction torque is generated between the inner peripheral surface of the rotating coil spring 110 and the fixing member 106 in contact with the inner peripheral surface. This friction torque prevents the rotation of the movable member 108. However, when there is one sheet of paper, the movable member 108 exerts a pressing force of the coil spring 66 because the rotational force transmitted from the feed roll 24 via the back surface of the sheet is large. Continue to follow the rotation while receiving. After the sheet passes through the nip portion 76, the feed roll 24 stops at the position shown in FIG. 2 and ends the sheet feeding operation.

  On the other hand, when two or more sheets are guided to the nip portion 76, the friction between the half-moon roll 68 of the feed roll and the friction member 82 of the retard roll 26 is smaller than the friction force between the sheets, causing slippage. . Thereby, the rotational force transmitted from the feed roll 24 is interrupted, and the retard roll 26 stops rotating by the above-described friction torque. Subsequently, the sheet in contact with the retard roll 26 is also stopped by the frictional force of the friction member 82. In this way, only the uppermost sheet in contact with the feed roll 24 is separated and fed.

  When the movable member 108 rotates on the fixed member 106, a convex portion 120 is formed on the fixed member 106, a concave portion 114 is formed on the movable member 108, and the convex portion and the concave portion are fitted and slid in the axial direction. Therefore, torque instability can be prevented. That is, the pressing force by the pressing spring 66 is applied in the radial direction of the retard roll 26, whereas the sliding surface of the fitting portion 116 is provided in the axial direction. Furthermore, the area of the sliding surface of the fitting portion 116 is smaller than the friction portion 122. Therefore, since it is difficult to be affected by the bending and friction of the sliding surface due to the pressing force of the pressing spring 66, torque stability can be realized.

  When the fixed member 106 is replaced due to wear of the friction portion 122 of the fixed member 106, the old fixed member may be removed from the movable member 108 and a new fixed member may be incorporated into the movable member 108, thereby wasting resources. The replacement work can be easily performed without any problems. Furthermore, since the shape of the fixing member 106 using a metal material is simple and downsized, the cost can be reduced.

   Next, a second embodiment according to the present invention will be described with reference to FIG.

  In addition, the same code | symbol is attached | subjected to the member demonstrated in 1st Embodiment, and the overlapping description is abbreviate | omitted.

  In the second embodiment, a movable shaft portion 86 is formed in the movable member 108 so as to be recessed in the axial direction in the axial direction. On the other hand, a bearing portion 90 is formed to protrude from the movable bearing member 64. The bearing 90 is inserted into the movable shaft 86 and one end of the torque limiter 78 is rotatably supported by the movable bearing member 64.

  For this reason, the shaft portion protruding from the movable member 108 is eliminated, and the torque limiter 78 can be further downsized.

  As described above, the present invention can be used in a paper feeding apparatus such as an image forming apparatus that needs to realize stable paper supply and cost reduction.

1 is a cross-sectional view of an image forming apparatus according to an embodiment of the present invention. It is a perspective view showing a paper feeder concerning an embodiment of the present invention. It is a perspective view which shows the retard roll attachment state which concerns on embodiment of this invention. It is a disassembled perspective view of the torque limiter which concerns on embodiment of this invention. It is sectional drawing of the torque limiter which concerns on embodiment of this invention. It is sectional drawing of the torque limiter which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Image forming apparatus main body 20 Paper feed cassette 22 Paper feed main body part 24 Feed roll 26 Retard roll 62 Fixed bearing member 64 Movable bearing member 66 Pressing spring 78 Torque limiter 80 Roll surface 84 Fixed shaft part 86 Movable shaft part 88 Protruding part 90 Bearing part 106 Fixed member 108 Movable member 110 Coil spring 114 Concave part 116 Fitting part 120 Convex part 122 Friction part

Claims (8)

A first member having a cylindrical inner wall; a second member having a cylindrical outer wall, the outer wall being disposed inside the inner wall of the first member; and an inner wall of the first member; It is arrange | positioned between the outer walls of the said 2nd member, and between the said 1st member and the said 2nd member according to the torque when the said 1st member and the 2nd member rotate relatively An elastic member that changes the friction between the first member and the second member, a circular concave portion that is recessed in the axial direction, and a circular protrusion that protrudes in the axial direction on the other side. The torque limiter is formed by forming a portion and fitting the concave portion and the convex portion in the axial direction.   A movable member having a cylindrical inner wall and a cylindrical roll surface, a fixed member having a cylindrical outer wall, the outer wall being disposed inside the inner wall of the movable member, and the movable member being the fixed member An elastic member that changes friction between the fixed member and the movable member according to torque when rotating relative to the shaft, and is recessed in the axial direction in either the movable member or the fixed member A retard roll in which a circular concave portion is formed on the other side and a circular convex portion protruding in the axial direction is formed, and the concave portion and the convex portion are fitted in the axial direction.   The retard roll according to claim 2, further comprising a bearing member that rotatably supports the movable member.   The retard roll according to claim 3, wherein the movable member has a shaft portion protruding in the axial direction, and a bearing member is fitted to the outside of the shaft portion.   The retard roll according to claim 3, wherein the movable member has a shaft portion that is recessed in the axial direction, and a bearing member is fitted inside the shaft portion.   A feed roll rotatably supported; a retard roll provided opposite to the feed roll; and an urging means for urging the retard roll toward the feed roll. A movable member having a cylindrical inner wall and a cylindrical roll surface that contacts the feed roll; a fixed member having a cylindrical outer wall disposed on the inner side of the movable member; and the movable member Having an elastic member that changes friction between the fixed member and the movable member in accordance with torque when rotating with respect to the fixed member, and the movable member has a circular concave portion recessed in the axial direction. The sheet feeding device, wherein the fixing member is formed with a circular convex portion protruding in the axial direction, and the concave portion and the convex portion are fitted in the axial direction.   The retard roll further includes a bearing portion that rotatably supports the movable member, and the biasing means is constituted by a pressing spring, and the bearing member is pressed by the pressing spring. The sheet feeding device according to claim 6.   An image forming apparatus comprising the sheet feeding device according to claim 6.

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