JPH11322105A - Sheet feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To unnecessitate a pressurizing mechanism of a separating roller by a spring, to reduce cost and to improve accuracy of biting amount of a feed roller and the separating roller. SOLUTION: A separating roller shaft 7 of a separating roller 6 to be combined with a feed roller 4 to feed a sheet P is molded with a resin which is more elastic than iron and stainless steel to be general shaft materials and is easy to bend. The material and the diameter of the shaft are set so that biting between the feed roller 4 and the separating roller 6 may be changed corresponding to thickness and stiffness of the sheet P and proper biting amount may be obtained, when the thick sheet and the sheet with stiffness are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding apparatus used in an image forming apparatus such as a copying machine, a facsimile, a printer and the like for use in original feeding, tray transfer paper feeding, manual transfer paper feeding, double-sided feeding, and the like.

[0002]

2. Description of the Related Art For example, in a sheet feeding apparatus disclosed in Japanese Patent Publication No. 7-17286, a sheet feeding apparatus using a mis-separation method has been proposed. This sheet feeding apparatus includes a tray bottom plate on which a large number of sheets are placed, a bottom plate pressing member, a pickup roller, a feed roller, a feed roller shaft, a separation roller, a separation roller shaft, a support arm, a fulcrum, a separation pressure spring, and a frame. , And front and rear side plates.

The feed roller is supported by front and rear side plates, and the separation roller is supported by a support arm supported by the front and rear side plates with the fulcrum of the support arm as a center of rotation. The support arm is connected to the front and rear side plates by a separation pressure spring, and when feeding a thick sheet or a sheet with a strong stiffness, a bite amount of a roller described later is displaced in accordance with the sheet thickness and the stiffness, and an appropriate The pressure of the separation pressure spring is set so as to obtain the bite amount. The feed roller and the separation roller are provided in correspondence with each other, and the outer periphery of these rollers is formed with alternating concave and convex portions in a comb shape. The protrusions of the separation roller correspond to the recesses of the feed roller. Further, the feed roller and the separation roller are alternately arranged so that the outer periphery of each convex portion slightly enters the corresponding concave portion and bites in a non-contact state, and these rollers are biting portions (nip portions). The sheet is sandwiched between the first and second sheets so as to impart a lateral waveform deformation to the sheet. When the feed roller is driven in the feeding direction and the separation roller is driven in the reverse direction, when the two sheets are fed in a superposed state (double feeding), the double feeding sheet is separated, and only the uppermost sheet is separated. Is supplied.

[0004]

In such a conventional sheet feeding apparatus using the separation method, the amount of biting between the rollers can be displaced on the axis of the separation roller in order to cope with a thick sheet or a sheet having a strong stiffness. There is a supporting plate which has a pressure spring for applying an appropriate pressure to the sheet between the rollers at the time of feeding the sheet. A positioning mechanism is required, the cost of parts and assembly increases, and the initial position accuracy of the separation roller due to the increase in the number of parts, that is,
There is a problem in that the accuracy of the bite amount between the rollers in the initial stage is reduced.

The present invention has been made in view of such conventional problems,
It is an object of the present invention to provide a sheet feeding device capable of reducing costs by reducing parts costs and assembly costs by eliminating a pressing mechanism of a separation roller by a spring, and improving the accuracy of a biting amount of a feed roller and a separation roller.

[0006]

According to a first aspect of the present invention, in order to achieve the above object, a plurality of convex portions projecting in the axial direction are provided at predetermined intervals in the axial direction. And a plurality of convex portions protruding in the axial direction are arranged at predetermined intervals in the axial direction and rotate in a direction opposite to the sheet conveying direction. A sheet feeding device for combining comb teeth-shaped separation rollers alternately so as to bite into each of the projections, and separating and feeding sheets one by one between the conveyance roller and the separation roller. Wherein the shaft of the separation roller is a resin molded product.

According to a second aspect of the present invention, the outer diameter of the shaft of the separation roller is made larger at the portion where the separation roller is fitted to the support than at other portions.

According to a third aspect of the present invention, there is provided a comb-shaped conveying roller which rotates in a sheet feeding direction by arranging a plurality of convex portions projecting in the axial direction at predetermined intervals in the axial direction, A plurality of protrusions projecting in the axial direction are arranged at predetermined intervals in the axial direction, and a comb-shaped separation roller rotating in the direction opposite to the sheet conveying direction is alternately arranged so as to bite each of the protrusions. In a sheet feeding apparatus that separates and feeds a sheet one by one between the transport roller and the separation roller, a support that rotatably supports the separation roller is formed of a cantilever-shaped resin molding. It is characterized by becoming a product.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view (A) showing an embodiment of a sheet feeding apparatus according to the present invention and an enlarged sectional view (B) of a main part. The sheet feeding device according to the present embodiment includes a tray bottom plate 1 on which a large number of sheets P are placed, a bottom plate pressing member 2, a pickup roller 3, a feed roller 4, a feed roller shaft 5, a separation roller 6, a separation roller shaft 7, and It is composed of a frame (not shown) and front and rear side plates. In the figure, reference numeral 8 denotes a biting portion (nip portion) between the feed roller 4 and the separation roller 6.

The feed roller 4 is driven to rotate in the direction of arrow A by a feed roller shaft 5 supported by the front and rear plates, and the separation roller 6 is driven by a separation roller shaft 7 supported by a support arm supported by the front and rear plates. It is driven to rotate in the direction of the middle arrow B. Although not shown, each shaft is supported via a bearing. The separation roller shaft 7 is formed of a resin that is more elastic and more flexible than iron or stainless steel, which is a general shaft material, and is suitable for feeding a thick sheet or a stiff sheet according to the thickness and stiffness of the sheet. The material and the shaft diameter are set so that the bite between the feed roller 4 and the separation roller 6 changes and an appropriate bite amount can be obtained.

The feed roller 4 and the separation roller 6 are provided in correspondence with each other, and convex portions 4a and 6a are formed at predetermined intervals on the outer periphery of the rollers 4 and 6, respectively. Are concave portions and have a comb shape.
These protrusions 4a, 6a are formed by the protrusions 4a of the feed roller 4.
The concave portions of the separation roller 6 are arranged alternately so that the convex portions 6a of the separation roller 6 slightly enter into the concave portions of the feed roller 4 and bite in a non-contact state.
The non-bite portion serves as the nip portion 8 to sandwich the sheet P, and imparts a lateral waveform deformation to the sheet P.

When the feed roller 4 is driven in the direction of arrow A and the separation roller 6 is driven in the direction of arrow B, the sheet P stacked on the tray bottom plate 1 pressed by the bottom plate pressing member 2 is moved. When two sheets are fed together (double feed), the lower (separation roller 6 side) multi-feed sheet is separated and only the uppermost sheet is fed.

When a thick sheet or a stiff sheet is fed, the separation roller shaft 7 is easily bent.
Radial load increases at the fitting part between
Since the durability is inferior, the separation roller shaft 7 is provided with a fitting portion with a bearing 9 supporting only both ends (only one end is shown in the figure), and the other portion is fitted with the bearing 9. The shaft diameter of the part is larger than the other parts. For this reason, when feeding sheets, especially when feeding thick or stiff sheets,
The fulcrum of the deflection of the shaft 7 is not at the fitting portion with the bearing 9 but at a portion between the positions supported by the bearing 9. Even if the bending portion is bent at a small diameter portion, it hardly bends at the fitting portion with the bearing 9. Radial load is reduced.

FIG. 2 is a side view showing another embodiment of the sheet feeding apparatus according to the present invention. With the configuration as in the previous embodiment, when the sheet is fed, particularly when a thick sheet or a stiff sheet is fed, the separation roller shaft 7 bends and the separation roller 6 is bent.
The axial center position is shifted between the center and the end of the sheet, the cylindricity formed by the convex portion 6a is deteriorated, the sheet conveyance force is not uniform between the center and the end, and slip or skew may occur during feeding. There is. Therefore, in the sheet feeding apparatus of the present embodiment, at least a portion 10a supporting the shaft 7 of the frame 10 supporting the shaft 5 of the feed roller 4 and the separation roller shaft 7 via bearings is made of resin like a cantilever. It is formed by molding into a simple lever shape. The lever-shaped support portion 10a is set so that when a load is applied to the separation roller shaft 7, the distance between the shafts 5 and 7 can be changed to a state where an appropriate bite amount can be obtained. In this way, the separation roller shaft 7 does not bend even when overloaded, and the lever-shaped support portion 10a of the frame 10
Since the shaft 7 is bent, the material of the shaft 7 may be iron or stainless steel which is a general shaft material.

[0015]

According to the first aspect of the present invention, as described above, the separation roller shaft is formed of a resin molded product among the conveyance roller and the separation roller for sandwiching the sheet. This eliminates the need for a pressurizing mechanism, and has the effect of reducing costs by reducing parts costs and assembly costs, and improving the accuracy of the feed amount of the feed roller and the separation roller.

According to the second aspect of the present invention, as described above, the outer diameter of the shaft of the separation roller is larger at the portion where the separation roller is fitted to the support than at other portions. In addition to the above-described common effects, there is an effect that the radial load at the fitting portion of the shaft of the separation roller with the bearing is reduced, and the durability is improved.

According to the third aspect of the present invention, as described above, the support portion of the separation roller of the conveyance roller and the separation roller sandwiching the sheet is formed of a cantilever-shaped resin molded product. In addition to reducing the cost of parts and assembling, it is possible to not only reduce the cost and improve the accuracy of the bite amount of the feed roller and the separation roller, but also eliminate the bending of the separation roller, thereby eliminating the conveyance failure due to slip and skew during sheet feeding. There is an effect that can be.

[Brief description of the drawings]

FIG. 1A is a side view showing an embodiment of a sheet feeding apparatus according to the present invention, and FIG.

FIG. 2 is a side view showing another embodiment of the sheet feeding apparatus according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 tray bottom plate 2 bottom plate pressing member 3 pickup roller 4 feed roller 4a convex portion 5 feed roller shaft 6 separation roller 6a convex portion 7 separation roller shaft 8 biting portion (nip portion) 9 bearing 10 frame 10a lever-shaped supporting portion P sheet

Claims (3)

[Claims] A plurality of convex portions projecting in the axial direction arranged at predetermined intervals in the axial direction and rotating in a sheet feeding direction; and a plurality of convex portions projecting in the axial direction. Are arranged at predetermined intervals in the axial direction, and comb-shaped separating rollers that rotate in the direction opposite to the sheet conveying direction are alternately combined so as to bite each of the convex portions. A sheet feeding device for separating and feeding one sheet at a time between the separation roller and the separation roller, wherein the shaft of the separation roller is a resin molded product. 2. The sheet feeding device according to claim 1, wherein the outer diameter of the shaft of the separation roller is larger at the portion where the separation roller is fitted to the support than at other portions. 3. A comb-shaped conveying roller rotating in the sheet feeding direction with a plurality of protrusions projecting in the axial direction arranged at predetermined intervals in the axial direction, and a plurality of protrusions projecting in the axial direction. Are arranged at predetermined intervals in the axial direction, and comb-shaped separating rollers that rotate in the direction opposite to the sheet conveying direction are alternately combined so as to bite each of the convex portions. A sheet feeding device that separates and feeds the sheet one by one between the separation roller and the separation roller, wherein the support portion that rotatably supports the separation roller is a cantilever-shaped resin molded product. The sheet feeding device according to claim 1, wherein