JPH082726A - Sheet separating and feeding mechanism - Google Patents

Abstract

PURPOSE:To provide a sheet separating and feeding mechanism which realizes highly accurate separating performance with simple constitution. CONSTITUTION:A sheet separating mechanism is provided with a sheet cassette for loading sheets, a feed roller 3 for feeding the sheets loaded on the sheet cassette, a driven roller 4 for abutting on the feed roller 3 to be driven, and a torque limiter, utilizing a coil spring 6, used for the driven roller 4, and drives the feed roller 3 to separate and feed the sheets one by one from the sheet cassette. In a fixed drum part 5 of the torque limiter, a support part 7, a coil spring receiver 8, a spring core art 9, an insertion pin part 10 and another support part 7 are respectively and integratedly molded, and the support parts 7 are respectively fitted to torque limiter fitting parts 2 and retained to be energized toward the feed roller 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet separating / feeding mechanism for separating and feeding sheets installed in an image forming apparatus such as a copying machine, a laser beam printer and a facsimile.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus such as a copying machine or a laser beam printer is equipped with a sheet separating / feeding mechanism for separating and feeding the sheets stacked on a sheet feeding cassette or a sheet feeding tray one by one. ing. In order to improve the separation performance of the sheet separating / feeding mechanism, it is generally practiced to use a torque limiter using a coil spring for a driven roller that abuts the feeding roller.

The structure of a sheet separating / feeding mechanism using the above torque limiter will be described with reference to FIG. 51
Is a feeding roller, which is rotationally driven by a driving force transmitted from a driving source (not shown). Reference numeral 52 denotes a driven roller, which is brought into pressure contact with the feeding roller 51 and is driven to rotate. The torque limiter is composed of the driven roller 52 and the fixed drum 5 incorporated therein.
3, and a coil spring 54 built in between the driven roller 52 and the fixed drum 53.

The coil spring 54 is elastically lightly wound around the spring core portion 52a inside the driven roller 52 and the spring core portion 53a of the fixed drum 53. The rotation of one end of the coil spring 54 is restricted by a restriction portion 52b at the end of the driven roller 52, and the coil spring 54 opens in the loosening direction only when the driven roller 52 rotates in the sheet feeding direction. The driven roller 52 is wound around the fixed drum 53 so as to be rotatable.

When the torque limiter is attached to the image forming apparatus, rotation of the fixed drum 53 is restricted by a driven roller shaft 55 penetrating the fixed drum 53 of the torque limiter, and the driven roller shaft 55 is attached to a main frame of the apparatus (not shown). ), The driven roller shaft 55 is supported so as to be parallel to the shaft of the feeding roller 51 by passing between the left and right side plates, and the driven roller 52 is fixed while elastically urging the driven roller 52 toward the feeding roller 51 side. .

The separating operation of the sheet separating / feeding mechanism will be described. When the sheet is guided to the nip portion between the feeding roller 51 and the driven roller 52, both rollers nip the sheet and follow the rotation of the feeding roller 51. Perform the feeding operation. At this time, the coil spring 54 in the driven roller 52 is twisted in the loosening direction of the coil diameter by the rotational force from the roller peripheral surface side, so that the friction between the fixed drum 53 and the coil spring 54 is reduced, and the driven roller 52 is Is rotated by the feeding roller 51.

On the other hand, when two or more sheets are guided between the feeding roller 51 and the driven roller 52, the friction between the sheets is smaller than the friction between the fixed drum 53 and the coil spring 54. Therefore, the driven roller 52 does not rotate, and only the uppermost sheet that is in contact with the feeding roller is conveyed as the feeding roller 51 rotates while sliding on the sheet below it, and the second and subsequent sheets are conveyed. It stops together with the driven roller 52. As described above, the sheets are separated and fed one by one.

[0008]

However, in the above-described conventional sheet separating / feeding mechanism, since the driven roller shaft 55 is fixed between the left and right side plates of the apparatus body, the left and right side plates and the left and right side plates are positioned to position the driven roller 52. It was greatly affected by the dimensional accuracy of the driven roller shaft 55. Further, since the driven roller shaft 55 for fixing the torque limiter needs to be separate from the torque limiter and long enough to pass between the frames of the apparatus body, the manufacturing cost of the apparatus increases.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a sheet separating / feeding device which realizes highly accurate separating performance with a simple structure.

[0010]

A typical means for solving the problems of the prior art and applied to the embodiments described below is a sheet stacking means for stacking sheets and a stacking means for stacking the sheets on the sheet stacking means. Feeding means for feeding the formed sheet, and following means for abutting and following the feeding means,
A torque limiter utilizing a coil spring as the driven means, and driving the feeding means to separate and feed the sheets one by one from the sheet stacking means, wherein a fixed drum of the torque limiter A torque limiter support member is integrally formed with the section, and the torque limiter support member is held by an attachment portion of the apparatus main body or the sheet stacking unit so as to be biased toward the feeding unit.

[0011]

According to the above-mentioned means, the torque limiter support member is integrally formed on the fixed drum portion of the torque limiter, and the torque limiter support member is urged toward the feeding means to the attachment portion of the apparatus main body or the sheet stacking means. By so holding, it is possible to realize highly accurate separation performance with a simple configuration. In addition, the number of parts can be reduced and the manufacturing cost can be reduced.

[0012]

【Example】

[First Embodiment]

An embodiment of the sheet separating and feeding mechanism according to the present invention to which the above means is applied will be described below with reference to the drawings. In this embodiment, a sheet cassette detachably attached to an image forming apparatus (for example, a copying machine, a laser beam printer, etc.) is used, and a sheet separating / feeding mechanism provided in the cassette will be described. 1 is a perspective explanatory view of a sheet cassette and a sheet separating / feeding mechanism, FIG. 2 is an explanatory view showing a configuration of a torque limiter of the sheet separating / feeding mechanism,
FIG. 3 is a sectional view of the torque limiter.

First, the schematic structure of the sheet separating and feeding mechanism will be described with reference to FIG. Reference numeral 1 denotes a sheet cassette as a sheet stacking unit that is detachably mounted on the laser beam printer, and the sheets can be stacked and stored in a housing-shaped cassette. A torque limiter mounting portion 2 for mounting a torque limiter, which will be described later, is formed at the end portion of the sheet cassette 1 on the sheet feeding direction side.

Reference numeral 3 is a feeding roller as a feeding means,
It is arranged on the apparatus main body side and is rotationally driven by a drive source not shown. The feeding roller 3 conveys the sheet fed from the cassette 1 to the downstream side. Reference numeral 4 denotes a driven roller as a driven means, which comes into contact with the feeding roller 3 and is driven to rotate. The driven roller 4 includes a fixed drum portion 5 and a coil spring 6 that form a torque limiter. The driven roller 4, the fixed drum portion 5, and the coil spring 6 are attached to the torque limiter attachment portion 2 of the cassette 1.

Next, the structure of the torque limiter will be specifically described with reference to FIGS. 2 and 3. In FIG. 2, a fixed drum portion 5 constituting a torque limiter is integrally provided with a support portion 7 as a torque limiter support member, a coil spring receiver 8, a spring core portion 9, an insertion pin portion 10, and a support portion 7 from the right. It is molded. A pin fixing claw 11 is formed at the left end of the insertion pin portion 10 while maintaining elasticity.

The driven roller 4 constituting the torque limiter has a structure in which a rubber roller portion 13 is fitted around a cylindrical movable drum portion 12 made of resin. Further, the movable drum portion 12 has a cylindrical spring core portion at the inner left end thereof.
14 and the regulating portion 15 of the coil spring 6 are integrally formed, and the inner circumference of the movable drum portion 12 and the spring core portion 14 are formed.
The coil spring 6 is configured to be housed in the gap between the and.

As shown in FIG. 3, the coil spring 6
Is a spring having the same outer diameter of the movable drum portion 12 and the fixed drum portion 5 with the insertion pin portion 10 of the fixed drum portion 5 inserted and set in the cylinder of the spring core portion 14 in the movable drum portion 12. Core part 14 and spring core part 9
Are fitted around the outer circumference of each of them in a state of being elastically wrapped, and are housed in the movable drum part 12. At this time, the movable drum portion 12 and the fixed drum portion 5 are fitted so as to rotate integrally by the pin fixing claw 11 at the left end of the insertion pin portion 10. The rotation of one end of the coil spring 6 is regulated by the regulation portion 15 of the movable drum portion 12, and the coil spring 6 is wound in a direction that loosens when the driven roller 4 rotates in the sheet feeding direction.

As shown in FIG. 2, the torque limiter can be easily incorporated in the cassette 1 by fitting the support portions 7 integrally formed at both ends of the fixed drum portion 5 into the torque limiter mounting portion 2 of the cassette 1. You can At this time, the support portion 7 is fixed by a snap fit at the inlet of the torque limiter mounting portion 2 while being biased upward by the pressure spring 16.

In the torque limiter incorporated in the cassette 1, the driven roller 4 is automatically arranged at a position facing the feeding roller 3 at the same time when the cassette 1 is mounted on the apparatus main body, and the driven roller 4 is supported. Pressure spring for urging the part 7
The roller 16 abuts on the feeding roller 3 while being elastically biased.

In the above structure, the coil spring 6 is opened in the loosening direction only when the number of sheets guided to the nip portion of the feeding roller 3 and the driven roller 4 is one, and the coil spring 6 is opened on the spring core portion 9 of the fixed drum portion 5. When the number of sheets is two or more, the coil spring 6 does not loosen and is fixed while being wound around the spring core 9, so that the uppermost sheet in contact with the feeding roller 3 is rotated. Only separated feed.

As described above, according to the present invention, the fixed drum portion 5 constituting the torque limiter, the support portion 7, the coil spring receiver 8, the spring core portion 9, the insertion pin portion 10,
Since the support part 7 and the support part 7 are integrally formed, high-precision separation performance can be realized with a simplified structure. In addition, the number of parts can be reduced and the manufacturing cost can be reduced.

[Second Embodiment]

Another example of the sheet separating / feeding mechanism will be described with reference to FIG. Since the schematic structure of the sheet separating / feeding mechanism is the same as that of the first embodiment, the same members are designated by the same reference numerals and the description thereof is cited. Hereinafter, the structure of the torque limiter, which is a characteristic point, will be mainly described.

In this embodiment, a guide member 17 for guiding the sheet conveyance is integrally formed with a part of the fixed drum portion 5 which constitutes the torque limiter shown in the first embodiment. Since the guide member 17 has a function of reliably guiding the sheet to the nip portion between the feeding roller 3 and the driven roller 4, it is possible to stabilize the behavior of the sheet before separation, so that the separation by the torque limiter is performed. It can be expected to further improve the performance.

[Third Embodiment]

Another example of the sheet separating / feeding mechanism will be described with reference to FIG. Since the schematic structure of the sheet separating / feeding mechanism is the same as that of the first embodiment, the same members are designated by the same reference numerals and the description thereof is cited. Hereinafter, the structure of the torque limiter, which is a characteristic point, will be mainly described.

In this embodiment, a guide member 17 for guiding the sheet conveyance is integrally formed on a part of the fixed drum portion 5 which constitutes the torque limiter shown in the first embodiment.
Further, an arm 18 for rotatably mounting the torque limiter around the fulcrum shaft A on the apparatus main body side is integrally formed. The driven roller 4 constituting the torque limiter is rotatably supported by the arm 18 around the fulcrum axis A at a position where it can contact the feeding roller 3 on the apparatus body side, and is fed by a spring (not shown). It is elastically biased to the roller 3 side.

According to the above construction, by setting the fulcrum shaft A to be parallel to the axis of the feeding roller 3, the driven roller 4 can be surely brought into contact with the feeding roller 3 in parallel. Optimal separation conditions can be realized without being affected by a spring (not shown) that urges the No. 4 spring.

In each of the embodiments described above, the sheet separating / feeding mechanism is provided in the sheet cassette 1. However, the present invention is not limited to this, and the sheet separating / feeding mechanism is integrally provided in the apparatus main body side. May be. It

[0032]

As described above, according to the present invention, a torque limiter supporting member is integrally formed on a fixed drum portion of a torque limiter, and the torque limiter supporting member is used as a feeding means at a mounting portion of an apparatus main body or sheet stacking means. By holding so as to urge toward, it is possible to realize highly accurate separation performance with a simple configuration. In addition, the number of parts can be reduced and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a perspective view illustrating a sheet cassette and a sheet separating / feeding mechanism according to a first exemplary embodiment.

FIG. 2 is an explanatory diagram showing a configuration of a sheet separating / feeding mechanism.

FIG. 3 is a sectional view of a torque limiter.

FIG. 4 is an explanatory diagram showing a configuration of a sheet separating / feeding mechanism according to a second embodiment.

FIG. 5 is an explanatory diagram showing a configuration of a sheet separating / feeding mechanism according to a third embodiment.

FIG. 6 is an explanatory diagram of a conventional sheet separating / feeding mechanism.

[Explanation of symbols]

 1 ... Sheet cassette 2 ... Torque limiter mounting part 3 ... Feeding roller 4 ... Following roller 5 ... Fixed drum part 6 ... Coil spring 7 ... Support part 8 ... Coil spring receiver 9,14 ... Spring core part 10 ... Insertion pin part 11 … Pin fixing claw 12… Movable drum part 13… Rubber roller part 15… Restriction part 16… Pressure spring 17… Guide member

Claims (3)

[Claims] 1. A sheet stacking unit for stacking sheets, a feeding unit for feeding the sheets stacked on the sheet stacking unit, and a follower unit that is driven by contacting the feeding unit. A sheet separating mechanism that uses a torque limiter that uses a coil spring as the driven means, drives the feeding means, and separates and feeds the sheets one by one from the sheet stacking means, the fixed drum of the torque limiter. The sheet separating / feeding device is characterized in that a torque limiter supporting member is integrally formed with the section, and the torque limiter supporting member is held by the mounting portion of the apparatus main body or the sheet stacking means so as to be biased toward the feeding means. Sending mechanism. 2. The sheet separating / feeding mechanism according to claim 1, wherein the fixed drum portion of the torque limiter is formed integrally with a guide member for guiding the sheet. 3. The sheet separating apparatus according to claim 1, wherein a support arm is provided integrally with the fixed drum portion of the torque limiter, and the support arm is rotatably attached to the apparatus main body about a fulcrum shaft of the support arm. Feeding mechanism.