JPH05105246A - Paper sheet feeder - Google Patents

Abstract

(57) [Summary] [Purpose] A simple structure that can reliably separate and feed paper one by one from a stack of paper placed in a paper cassette, does not take up space, and does not select paper types It is an object of the present invention to provide a sheet feeding device that does not generate a crease or a flicking sound. [Structure] A sheet feeding cassette 1 has a parallelogram cross section in which a front wall 1a and a rear wall 1b are retracted upward to form a slanted parallelogram section, and a front end of a bottom plate 8 is located at a position apart from the cassette front wall 1a. Abutting the stack of sheets 2 placed on each other by pushing up the bottom plate and pushing up the sheets so that the sheets are stacked so as to be displaced rearward from the sheets below, and the separating member 7 provided at the center of the front wall of the cassette is placed. Flip only the top edge of the top paper at the rear edge,
The paper is fed by the paper feed roller 3 provided on the separating member 7. The second and subsequent sheets remain without being repelled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording paper feeding device for an image forming apparatus.

[0002]

2. Description of the Related Art As a sheet feeding device for recording sheets such as transfer sheets for image forming apparatuses such as copiers, facsimiles, printers, etc., a front end face of a bundle of recording sheets is abutted against a rear face of a front wall of a sheet feeding cassette on a movable bottom plate. Then, the bottom plate is pushed up by the pressure arm to bring the surface of the recording paper bundle into pressure contact with the paper feed roller, and the paper feed roller is rotated by a predetermined amount in response to the paper feed signal, so that the recording paper is delivered from above. In this case, the corner claws that press both corners of the front edge of the recording paper bundle from above buckle the top one or several sheets of the recording paper bundle, thereby separating the recording paper and feeding only the topmost one. The corner claw separation method, in which the paper is fed over the corner claws by the frictional force with the roller, has a simple structure and is widely used because it saves space and is inexpensive.

However, in the corner claw separation method, since the recording paper to be fed over the corner claws, the corners must be bent with a small radius of curvature.
Sheets with strong electrostatic attraction between sheets such as P sheets cannot be separated. Further, at the time of separation, the corners of the recording paper are broken or a repellant sound is emitted. Although this method is simple, it does not necessarily have good separation performance and often involves double feeding.
Further, there is a problem that the last one sheet cannot be fed.

[0004]

DISCLOSURE OF THE INVENTION The present invention has the advantages of eliminating the above-mentioned problems of the sheet feeding device using the corner claws as the conventional separating means and being inexpensive and space-saving as in the case of the corner claws. Moreover, it is an object of the present invention to provide a sheet feeding device that can be separated regardless of the type of paper and does not cause creases or fluttering noises.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention mounts a bundle of recording paper on its movable bottom plate by abutting its front end face against the rear face of the front wall of a paper feed cassette and raising the bottom plate. Then, the upper surface of the bundle of recording papers is brought into pressure contact with the paper feed roller, and the paper feed roller is rotated to cause the recording paper separating means to move the uppermost 1
In a sheet feeding device of an image forming apparatus that separates and feeds only sheets, the sheet feeding cassette has a parallelogram cross-sectional shape in which a front wall of the sheet feeding cassette is inclined so that an upper part thereof recedes upstream in a sheet feeding direction. The bottom plate has a front end distant from the front wall of the paper feed cassette toward the upstream side in the paper feed direction, and the recording paper separating means is a plate-shaped member provided at the center of the width of the front end of the paper feed cassette. When the bottom plate is raised, the front end of the uppermost paper of the recording paper stack, which is displaced rearward as it goes up, is flipped out at the rear edge of the separating means, and the front ends of the second and subsequent sheets of paper are provided at such positions as to be hooked. The paper feed roller is provided so as to face the rear edge of the recording paper separating means across the recording paper feed passage.

[0006]

Since the sheet feeding device of the present invention is constructed as described above, when the front end surface of the recording sheet bundle is abutted against the rear surface of the front wall of the sheet feeding cassette and is placed on the movable bottom plate, the recording sheet bundle is recorded. The sheets are stacked so as to be shifted rearward as they go up, and the front end of the movable bottom plate is located rearward of the front wall of the cassette.Therefore, when the bottom plate is raised, the part that protrudes from the bottom plate of the front part of the recording paper. Is drooping due to the weight of the recording paper itself, the front portion of the recording paper is convexly curved upward, and the front end of each recording paper is displaced further rearward from the front end of the recording paper below it. The position of the trailing edge of the separating means is such that the front end of the uppermost paper of the recording paper bundle shifted as described above is repelled and the front and rear of the second and subsequent recording papers are hooked. If the bottom plate is stopped at the position where the upper paper is ejected, or if the bottom plate is ejected and then the bottom plate is slightly lowered, only the topmost paper is inserted between the paper feed roller and the separating means, and separated by the paper feed roller in contact with the upper surface. Paper is fed over the means.

By raising the bottom plate each time a paper feed signal is output, the topmost sheet at that time is fed one by one, and the last one of the sheets also protrudes beyond the bottom plate, so that the sheet is passed over the separating means. Are fed.

In the paper feeding apparatus of the present invention, since the separating means is located at the central portion of the width of feeding the recording paper, there is no occurrence of folds in the ears, and the paper is sharply released by bending it with a small radius of curvature as in the prior art. On the other hand, when the paper is ejected, the paper is hardly bent so that the creaking noise is small.

The problems of the invention other than the above and the means for solving the same will become apparent from the description of the embodiments described in detail below with reference to the drawings.

[0010]

Embodiments of the present invention will be described in detail below with reference to the drawings.

1 and 2 are a perspective view and a sectional view showing the structure of a first embodiment of the present invention. In this embodiment, the front wall 1a and the rear wall 1b of the paper feed cassette 1 are inclined so that the upper part retracts from the lower part, and the vertical cross section has a parallelogram shape. The bottom plate 8 is swingably provided by the upper end of an arm 8a rising from both rear ends of the bottom plate 8 being pivotally supported by a recessed portion provided at an approximately central portion of both side plates 1c of the sheet feeding cassette 1. ing. The front end of the bottom plate 8 is located apart from the front wall 1a of the sheet cassette. The bottom plate 8 can be raised and lowered by a bottom plate raising lever 9.

At the center of the upper edge of the front wall 1a of the sheet feeding cassette 1, there is fixed a separating member 7 which is curved so that the inner side is recessed and whose upper edge is oriented substantially horizontally rearward as shown in the drawing.
Further, a paper feed roller 3 is provided on the upper portion thereof in contact with the upper end of the separating member 7, and a sensor 6 for detecting a paper is provided immediately next to the paper feed roller 3. The paper feed roller 3 is rotated by a drive gear 5 which is rotationally driven by a drive source (not shown) via a clutch 4 in response to a paper feed signal. A conveyance guide 12 that guides the paper fed by the paper feed roller 3 is provided on the downstream side of the paper feed roller 3 and the separation member 7 in the paper feed direction. Also, the rear wall 1 of the feeding cassette 1
At the upper edge of b, the stack of sheets 2 placed in the sheet cassette 1
A retractable pressing member 10 for pressing the rear upper surface is provided.

Since the paper feeding device of this embodiment is constructed as described above, the recording paper stack 2 is placed on the bottom plate 8 by abutting the front end face thereof against the inner face of the cassette front wall 1a as shown in FIG. When placed, the sheets of the recording sheet bundle 2 are automatically shifted rearward from the sheets below and placed in a stacked state. After that, the rear portion of the bundle of recording sheets is pressed by the pressing member 10.

When the bottom plate raising lever 9 is raised and the bottom plate 8 is pushed up, as shown in FIG. 3, the portion of the bundle of recording sheets protruding from the front edge of the bottom sheet 8 is drooped downward by its own weight, and the rear edge of the sheet bundle is folded. Is pressed by the pressing member 10 so as not to move, so that the misalignment between the sheets becomes larger,
Only the topmost one tip is repelled by the rear edge of the separating member 7 and comes into contact with the sensor 6 to be detected. Sensor 6
The bottom plate 8 descends by a certain amount according to the sheet detection signal of, and descends together with the bottom plate 8 from the second sheet onward of the sheet bundle.
The curved portion of the sheet is stretched, and the leading end portion of the sheet enters between the sheet feeding roller 3 and the separating member 7. Then, this one sheet is guided by the conveyance guide 12 by the rotation of the paper feed roller 3 and conveyed to a predetermined conveyance path.

Although an example in which the sheet bundle trailing end pressing member 10 is a retractable arm is shown in the drawing, various known methods such as a slide type can be used for the sheet bundle trailing end pressing member.

Further, as shown in FIG. 4, a conductive material 11 such as copper is attached to the tip of the separating member 7 and is grounded to the machine body via a harness or the like, so that the static electricity of the paper fed in contact therewith. By removing the, the electrostatic attraction of the paper can be released and the separation can be facilitated. As a result, it becomes easy to separate OHP sheets, etc., which have a large electrostatic attraction,
Further, the torque of the paper feed roller 3 can be reduced, and the effect of energy saving can be obtained.

5 and 6 are views showing a second embodiment of the present invention. Members having the same functions as those of the first embodiment are designated by the same reference numerals. Also in this embodiment, the front wall 1a and the rear wall 1b of the paper feed cassette 1 have a parallelogram cross section with the upper part retracted, and the rear end wall 1b is provided with the sheet bundle pressing member 10 at the bottom of the cassette. A movable bottom plate 8 is swingably provided from near the center to the front, and can be raised and lowered by a bottom plate raising arm 9.

However, in this embodiment, the separating member 7 is swingably provided on the upper end of the sheet feeding cassette front wall 1a, and the separating member 7 is changed according to the change of the upper surface position of the sheet bundle 2 when the bottom plate 8 is raised. An arm 13 is provided as an interlocking means for displacing the sheet bundle at a position suitable for separating the uppermost sheet of the sheet bundle by repelling it. Further, the paper feed roller 3 and its drive motor 14 are integrated with a bracket fixed to the separation member 3 so that the paper feed roller can move while maintaining a fixed positional relationship as the separation member 7 moves. Is movably attached to.

The separating member 7, as shown in detail in FIG.
Separation claw 7a that separates the topmost sheet of the sheet bundle by repelling it
And the separated upper conveyance guide 7b of the uppermost paper are integrally connected. The separating claw 7a has a rear end edge formed in an arc shape protruding rearward at the central portion and curved so that the rear end is lowered. A support bracket 3a for the paper feed roller 3 is attached to the upper surface of the upper conveyance guide 7b, and an escape hole 7c is formed so that the lower end of the paper feed roller supported by this is exposed to the paper. An arm 13 for moving the separating member 7 is fixed to the rear end of the upper conveyance guide 7b in association with a change in the position of the upper surface of the sheet bundle that changes depending on the number of sheets when the bottom plate rises.

Now, as shown in FIG. 6, the sheet bundle 2 is placed on the bottom plate 8 lowered as shown in FIG. 6 by abutting the front end face thereof against the rear face of the cassette front wall 1a, and the bottom plate 8 is raised by the bottom plate raising arm 9 as shown in FIG.
When the sheet is pushed up by, the sheets of the sheet bundle are shifted rearward from the sheets below and are in a state of being easily separated from each other as described in the first embodiment. At this time, the interlocking arm 13
By the action of, the central rear end of the separating claw 7a of the separating member 7 hangs on the front end of the uppermost paper, and only the uppermost paper is curved at the front end as shown in FIG. By returning with a strainer, the front end of the paper is inserted between the paper feed roller 3 and the upper surface of the separation claw 7a. Next, when the paper feed roller 3 rotates, the paper is sent out between the upper conveying guide 7b and the separation claw 7a.

In this embodiment, the positions of the separating member 7 and the sheet feeding roller 3 change depending on the stacking amount of the sheet bundle on the bottom plate 8, so that the conveying roller 1 provided at a fixed position in the machine.
In order to smoothly convey the sheet to the conveying member 6 or the like, as shown in FIG. 7, a conveying guide 17 having an opening in a wide area is provided between the separating member 7 and the conveying means at a fixed position in the machine, or As shown in FIG. 10, it is preferable to provide a movable conveyance guide 18 in which the end portion on the inner side of the machine is pivotally supported at a fixed position so that the separation member 7 side can be displaced.

At the moment when the topmost sheet is repelled by the rear end of the separating claw 7a, the sheet hits the sensor 6 as described in the first embodiment, and the detection signal causes the bottom plate 8 to stop rising. Stops before the separation claw and keeps that state until the next paper feed signal arrives. At the next paper feed signal, the bottom plate rises further and the above operation is repeated.

As the number of sheets fed increases, the number of sheets on the bottom plate 8 decreases and finally becomes the last sheet as shown in FIG. However, even if the number of sheets becomes small, the interlocking arm 13 is lifted by the bottom plate and the separation claw 7a comes to a position where the front end of the sheet protruding from the bottom plate 8 is repelled, so that the sheets can be smoothly separated as in the case of a large number of sheets. ..

[0024]

As described above, according to the present invention, it is possible to ensure that the stack of sheets placed in the sheet feeding cassette 1 can be reliably constructed with a simple structure, at a low cost, without taking up space, and without selecting the type of sheet.
It is possible to feed the sheets one by one without causing a crease or a flickering noise.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a first embodiment of the present invention.

FIG. 2 is a vertical sectional view thereof.

FIG. 3 is an explanatory diagram explaining its operation.

FIG. 4 is a cross-sectional view showing an example in which static electricity removing means is provided in the separating means.

FIG. 5 is a perspective view showing a configuration of a second exemplary embodiment of the present invention.

FIG. 6 is a vertical sectional view thereof.

FIG. 7 is an explanatory diagram explaining its operation.

FIG. 8 is another explanatory diagram illustrating the operation thereof.

FIG. 9 is still another explanatory diagram for explaining the operation.

FIG. 10 is a cross-sectional view showing an example of a paper guide unit between the separating unit and the in-machine conveying unit.

FIG. 11 is a perspective view showing a configuration of a separating member according to a second embodiment.

[Explanation of symbols]

 1 Paper Feed Cassette 1a Cassette Front Wall 2 Paper Bundle (Record Paper Bundle) 3 Paper Feed Roller 6 Sensor 7 Separation Member 7a Separation Claw 7b Upper Transport Guide 8 Movable Bottom Plate 9 Bottom Plate Lifting Lever 10 Paper Bundle Pressing Member 11 Conductive Material (Static Removal means) 13 Interlocking arm (interlocking means) 14 Motor 16 Fixed transport member 18 Movable guide member

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location B65H 3/56 310 A 9148-3F 3/68 9148-3F G03G 15/00 309 7369-2H

Claims (6)

[Claims] 1. A sheet bundle of recording paper is placed on a movable bottom plate, with the front end surface of the sheet bundle abutting against the rear surface of the front wall of a sheet feeding cassette, and the bottom plate is raised to press the upper surface of the recording sheet bundle against a sheet feeding roller to feed the sheet. In a sheet feeding device of an image forming apparatus that separates and feeds only the uppermost one sheet by rotating a roller by a recording sheet separating means, the above-mentioned sheet feeding cassette has a front wall whose upper portion is located on the upstream side in the sheet feeding direction. It has a parallelogram cross-sectional shape that is inclined so as to move backward, the front end of the bottom plate is located away from the front wall of the paper feed cassette toward the upstream side in the paper feed direction, and the recording paper separating means is the front end of the paper feed cassette. A plate-shaped member provided at the center of the width, the front end of the uppermost paper of the recording paper stack being displaced backward as it goes up when the bottom plate is raised, is repelled by the rear edge of the separating means, and two sheets are provided. The front edge of the paper below the eye is placed so that it can be caught, The roller is provided so as to face the rear edge of the recording paper separating means across the recording paper feeding passage. 2. The paper feeding device according to claim 1, further comprising a member for pressing an upper surface of the bundle of recording papers on the upstream side of the paper feeding cassette in the paper feeding direction. 3. The paper feeding apparatus according to claim 1, wherein the recording paper separating means is provided with static electricity removing means. 4. The recording paper separating means is swingably provided on an upper edge of a front wall of a paper feed cassette, and the recording paper separating means is provided with the upper surface of the recording paper when the bottom plate rises. 2. An interlocking device for displacing the uppermost paper of the recording paper stack to a position suitable for repelling and separating the uppermost paper.
The paper feeder described in. 5. The paper feeding device according to claim 4, wherein the paper feeding roller and its drive motor are integrally movably attached to the recording paper separating means. 6. A guide member for guiding the conveyance of the recording paper from the paper feed roller to a conveying means provided at a fixed position on the downstream side of the paper feed roller can be displaced in accordance with the displacement of the paper feed roller and the recording separation paper means. The sheet feeding device according to claim 5, wherein the sheet feeding device is provided in the.