JPH11263459A - Paper feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeder capable of delivering a recording medium without biased delivery by restraining floating and slippage of the record medium. SOLUTION: A woodruff paper presser projection 120 smaller than a paper feeding roller 100 is formed on a flat surface part on the opposite side of a circular arc part 100a out of the paper feeding roller 100. A circular arc part of this paper presser projection 120 faces against a middle plate 60 in cases where the circular arc part of the paper feeding roller 100 is positioned on the opposite side of the middle plate 60 with a rotation axis 110 inbetween and stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeder for feeding a recording medium from a cassette tray provided in an image forming apparatus such as a copying machine, a printer, and a plotter.

[0002]

2. Description of the Related Art As an output device of a computer or a work station, an ink jet type image forming apparatus for forming an image on a recording medium by discharging ink, or an electrophotographic type forming apparatus for forming an image on a recording medium using a developer or the like. Image forming apparatuses are known. These image forming apparatuses are usually provided with a cassette tray in which a plurality of recording media are stored in a stacked state. The cassette tray is incorporated in the main body of the image forming apparatus so as to be freely taken in and out, and the recording medium stored in the cassette tray is fed at a predetermined timing to an image forming unit on which an image is formed.
This sheet feeding is performed by a sheet feeding device arranged above a portion of the cassette tray on the downstream side in the sheet feeding direction. This paper feeding device is composed of a paper feeding roller described later and the like.

[0003] The cassette tray usually has a rectangular bottom wall, and includes a cassette tub (frame body) having an open upper surface, and a rectangular middle plate on which a recording medium is loaded. One side of this middle plate is rotated near the bottom wall of the cassette tub,
The other side opposite to the one side is detachably separated from the bottom wall of the cassette tub, whereby the middle plate is inclined with respect to the bottom wall of the cassette tub.

Below the other side of the middle plate, there is arranged a compression coil spring which biases the other side upward to separate from the bottom wall of the cassette tub and inclines the middle plate. Further, above the other side of the middle plate, a paper feed roller for feeding out the recording medium loaded on the middle plate is arranged. With the middle plate loaded with the recording medium inclined with respect to the bottom wall of the cassette tub, the top recording medium among the loaded recording media comes into contact with the above-mentioned paper feed roller, and With the rotation, the uppermost recording medium is sent out in the sheet feeding direction from one side of the middle plate to the other side.

When loading a recording medium on the middle plate, the cassette tray is pulled out of the image forming apparatus, the middle plate is pressed down from above, and the whole of the middle plate is brought into contact with the bottom wall of the cassette tub. The plate is locked by a locking member, and a recording medium is loaded. When the cassette tray is pushed into the image forming apparatus after the recording medium is loaded on the middle plate, the locking of the locking member is released, and the other side of the middle plate is urged upward by the compression coil spring. . As a result, the middle plate is inclined with respect to the bottom wall of the cassette tub, and the uppermost recording medium among the recording media stacked on the middle plate abuts on the feed roller, and as described above, With the rotation of the roller, the uppermost recording medium is sent out from one side of the middle plate toward the other side.

[0006]

As described above, when the cassette tray accommodating the recording medium is pushed into the image forming apparatus, the locking of the locking member is released and the other side of the middle plate is compressed by the compression coil. It is urged upward by a spring. When the other side of the middle plate is urged upward in a vigorous manner, the recording medium loaded on the middle plate may be lifted or the loading position of the recording medium may be shifted. When the recording medium is conveyed in this state, the recording medium may be skewed.

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a sheet feeding device capable of suppressing the lifting or displacement of a recording medium and sending out the recording medium without skew.

[0008]

According to a first aspect of the present invention, there is provided a paper feeding apparatus having a rectangular bottom wall, a cassette tub having an open upper surface, and a side extending in a predetermined direction. A plurality of recording media are stacked, the other side of which is located near the bottom wall and extends in the predetermined direction on the side opposite to the one side and is inclined with respect to the bottom wall by coming and coming from the bottom wall. A cassette tray having a middle plate to be formed, and in an image forming apparatus for forming an image on a recording medium sent from the cassette tray, a plurality of recording media stacked on the middle plate, In a sheet feeding device for feeding one sheet at a time in a sheet feeding direction from one side to the other side,
(1) a feed roller shaft that extends in the predetermined direction above the other side of the middle plate and rotates around a longitudinal direction;
(2) a half-moon-shaped feed roller fixed coaxially with the feed roller shaft and rotated with rotation of the feed roller shaft;
(3) A paper holding projection fixed to a portion of the paper feed roller shaft opposite to the side where the arc portion of the paper feed roller is located and pressing a recording medium loaded on the middle plate from above. It is characterized by having.

Here, the paper feeder includes: (4) a pair of separation claws for pressing both end portions of a portion of the recording medium loaded on the middle plate located on the other side of the middle plate from above. May be provided.

[0010] The paper feed roller may be (5) a pair of paper feed rollers that abut on a portion between the pair of separation claws of the recording medium stacked on the middle plate.

Further, (6) the paper press projection may be located above a portion between the pair of separation claws of the recording medium stacked on the middle plate.

Further, the paper press projection may be configured to (7) come into contact with the recording medium when the recording medium loaded on the intermediate plate jumps up.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the paper feeder of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing the appearance of a copying machine in which an embodiment of the paper feeding apparatus of the present invention is incorporated.

On the top surface of a copying machine (which is an example of an image forming apparatus according to the present invention) 10, an original cover 12 which can be opened and closed is arranged. On the front side of the top surface, an operation panel display 14 for inputting the number of copies and the like is arranged.
The copying machine 10 is provided with a universal cassette (which is an example of a cassette tray according to the present invention) 16 in which a plurality of cut sheets are stored so as to be able to be taken in and out of the main body of the copying machine 10. The right side wall of the copying machine 10 is provided with a rectangular manual tray 18 (see FIG. 2) capable of feeding small-size recording paper such as postcards. As shown in FIG. 2, the manual feed tray 18 rotates around the lower side 18a in the direction of arrow C and opens to a position where a recording medium can be placed (a position indicated by a two-dot chain line). The left side wall of the copying machine 10 is provided with a paper discharge tray 20 on which recording paper on which an image is formed is stacked.

At the front of the copier 10, a rectangular front door 22 is provided.
However, it is fixed so that it may open to the near side with the lower side portion 22a as the center of rotation. By opening the front door 22, the inside of the copier 10 can be observed. Further, with the front door 22 kept open, a hook (not shown) disposed near the front door 22 is removed, so that a repulsive force of a damper (not shown) causes the upper portion of the main body of the copying machine 10 ( The front side portion of the optical system 28 and the photosensitive drum 32 described later) is pushed up. As a result, the copying machine 10 is divided into an upper body and a lower body (a part in which the universal cassette 16 and the like are incorporated).

Referring to FIG. 2, a procedure for forming an image by the copying machine 10 of FIG. 1 will be described.

FIG. 2 is a schematic diagram showing an outline of the internal structure of the copying machine 10. As shown in FIG. 2, the same components as those of FIG. 1 are denoted by the same reference numerals.

An original table glass 26 on which an original 24 is placed is disposed below the original cover 12. The original 24 is placed on the original platen glass 26 so that the image surface faces down.
Is placed, and the original 24 is pressed and fixed by the original cover 12. The image recorded on the document 24 is read by a well-known optical system 28 having a light source lamp (not shown) or the like, and light (broken line A) carrying information of the image recorded on the document is obtained. This light is applied to the photosensitive drum 32 uniformly charged by the charging unit 30 to form an electrostatic latent image. This electrostatic latent image is developed with the developer (toner) supplied from the developing unit 34 to form a developed image. On the other hand, a recording medium such as recording paper is
And the developed image is transferred to the recording medium in the transfer unit 36. The recording medium to which the developed image has been transferred is transported to the fixing unit 40 by the transport unit 38. A heat roller 42 and a press roller 44 are disposed in the fixing unit 40. The recording medium is conveyed while being sandwiched between these two rollers 42, 44, and the developed image is fixed on the recording medium. The recording medium on which the developed image has been fixed in this manner is discharged and stacked on the discharge tray 20. The toner remaining on the photosensitive drum 32 after the transfer is scraped off by the cleaning device 46. In addition, the recording medium can be fed from the manual feed tray 18, and the procedure for forming an image on the recording medium fed from the manual feed tray 18 is the same as described above.

The general configuration of the universal cassette 16 will be described with reference to FIGS.

FIG. 3 is a perspective view showing the universal cassette with the middle plate lowered, and FIG. 4 is a perspective view showing the universal cassette with the middle plate raised.

The universal cassette 16 is used for the copying machine 10.
(See FIGS. 1 and 2). The universal cassette 16 is a cassette tub 5 having a rectangular bottom wall 52 and a side wall 54 rising from the peripheral edge of the bottom wall 52.
0 is provided. On the bottom wall 52 of the cassette tub 50, a rectangular middle plate 60 which is about half the size of the bottom wall 52 and on which a recording medium is loaded is arranged. Middle plate 60
Are sent out in the direction of arrow E.

One side 62 of the middle plate 60 extends in the direction of arrow D, and is located near the center of the bottom wall 52 in the direction of arrow E. At both ends of this one side 62 in the direction of arrow D, a support plate 64 rises substantially at right angles from the one side 62. A hole 64a is formed in an upper portion of the support plate 64, and a projection (not shown) formed on the side wall 54 is fitted into the hole 64a. For this reason, the intermediate plate 60 can rotate between the position shown in FIG. 3 and the position shown in FIG.

On the side opposite to one side 62 of the middle plate 60, another side 66 extending in the direction of arrow D and coming into contact with and separating from the tip of the bottom wall 52 in the direction of arrow E is formed. Two compression coil springs 69 (see FIG. 8) are arranged on the back surface of the central portion of the other side portion 66. The upper ends of the two compression coil springs 69 are fixed to the center of the other side 66, and the lower ends are fixed to the bottom wall 52. The central portion of the other side 66 of the middle plate 60 is always urged upward by these two compression coil springs 69. Thus, the other side 6 of the middle plate 60
6 is urged upward to be pushed up and the one side 62 rotates near the bottom wall 52, whereby the middle plate 60 is inclined with respect to the bottom wall 52.

The middle plate 60 has four rectangular openings 68 formed therein. These openings 68 are for movement of side regulation plates 70 that regulate both ends of the recording medium loaded on the middle plate 60. The side regulating plate 70 includes a pair of L-shaped plates 70a and 70b, and is fixed to the bottom wall 52 so as to be movable in the direction of arrow D. These pair of plates 70a,
70b moves in the direction of arrow D in conjunction with it, and its position can be changed according to the size of the recording medium. Accordingly, by moving the pair of plates 70a and 70b to an appropriate position in accordance with the size of the recording medium, the middle plate 60 can record one type of recording medium of a plurality of types of recording media. Media can be loaded selectively.

When the pair of plates 70a and 70b is moved, the V-shaped size switching knob (not shown) is moved while being pinched. When the size switching knob is released when the pair of plates 70a and 70b are located at predetermined positions, the tip of the size switching knob is fitted into a hole (not shown) formed in the bottom wall 52, and the predetermined position is adjusted. A pair of plates 70
a, 70b are fixed.

A rear end regulating plate 80 is arranged on the bottom wall 52 near the center of one side 62 of the middle plate 60. The rear end regulating plate 80 moves in the direction of arrow F in conjunction with the movement of the middle plate 60, and regulates the rear end of the fed recording medium.

A pair of plates 70 constituting the side regulating plate 70
As shown in FIGS. 6 to 8, an L-shaped separation claw 90 (not shown in FIGS. 3 and 4) is fixed to each of the a and 70b, and moves together with the pair of plates 70a and 70b. I do. Further, the distal end portion 90a of the separation claw 90 is bent to feed the recording medium stacked on the middle plate 60 in the sheet feeding direction (arrow E).
Direction) Both ends of the tip are pressed from above. As will be described later, when the top one of the recording media stacked on the middle plate 60 is sent out with the rotation of the paper feed roller 100, the tip of the topmost recording medium is It is separated from the leading end portion 90a and separated from the second and subsequent recording media from the top. For this reason, it is possible to prevent double feeding in which two or more recording media are sent out in an overlapping manner.

With reference to FIGS. 5 to 8, a sheet feeding device disposed above the other side of the middle plate will be described.

FIG. 5 is an enlarged plan view showing the middle plate of the universal cassette with the middle plate raised and its vicinity, and FIG. 6 is a perspective view showing the paper feed roller and its vicinity. It is. FIG. 7 is a front view of FIG.
FIG. 3 is an enlarged perspective view showing one of two paper feed rollers. The universal cassette 16 shown in these figures is the same as the universal cassette 16 shown in FIGS.
Although they are the same as those described above, some of the members are slightly different in shape because of the schematic configuration.

As shown in FIGS. 5 and 6, a rotary shaft 110 extending in the direction of arrow D is disposed above the other side 66 of the middle plate 60. It is rotatably fixed to the main body of the copying machine 10 (see FIG. 2). A pair of paper feed rollers 100 are fixed to the rotating shaft 110. The pair of paper feed rollers 100 has a half-moon shape, and is fixed to a portion that is approximately one third of the length of the rotating shaft 110 from each of both longitudinal ends of the rotating shaft 110. The rotation shaft 110 normally stops in a state in which the paper feed roller 100 is up, that is, in a state in which the arc-shaped portion 100a of the paper feed roller 100 is located on the side opposite to the intermediate plate 60 with the rotation shaft 110 interposed therebetween. ing. On the basis of a control signal from a control device (not shown) built in the copying machine 10 (see FIG. 2), the rotation shaft 110 is turned at a predetermined timing by an arrow G.
One turn in the direction.

A flat surface portion of the sheet feeding roller 100 opposite to the arc-shaped portion 100a is provided with a sheet feeding roller 100.
A smaller half-moon-shaped paper holding projection 120 is formed. The arc-shaped portion 120a of the paper holding projection 120
Is that the arc-shaped portion 100a of the paper feed roller 100 is
When the vehicle is stopped at a position opposite to the intermediate plate 60 with respect to the intermediate plate 10, it faces the intermediate plate 60 as shown in FIGS. In addition, a separation sheet 67 for facilitating separation of the recording medium stacked on the middle plate 60 is attached to a portion of the middle plate 60 corresponding to a portion below the sheet feeding roller 100.

A description will be given of a process from loading of a recording medium on the middle plate 60 to preparation of sheet feeding.

The universal cassette 16 is pulled out from the main body of the copying machine 10 (see FIG. 1), and the middle plate 60 is pushed down. Thus, the middle plate 60 is locked and fixed to the locking member 130 in a state where the middle plate 60 is almost in contact with the bottom wall 52 (see FIGS. 3 and 4). When a large number of recording media are stacked on the middle plate 60 in this state and the universal cassette 16 is pushed into the main body of the copying machine 10, the locking of the locking member 130 is released. Almost at the same time as the release, the other side 66 of the middle plate 60 is vigorously pushed up by the compression coil spring 69, and the middle plate 60 is inclined with respect to the bottom wall 52. At this time, the middle plate 60
Is vigorously pushed up and stopped abruptly at the tip of the separation claw, so that the recording medium 140 loaded on the middle plate 60 tends to float or shift from the loaded position. It cannot be moved because it is pressed against the paper holding protrusion 120. For this reason, lifting and displacement of the recording medium 140 are prevented. Usually, the recording medium 140
Of these, the portion between the pair of separation claws 90 (the portion of the recording medium 140 between the pair of separation claws 90) is likely to float. For this reason, the paper feed roller 100 is arranged at a portion between the pair of separation claws 90, and the inner portion is configured to be pressed by the paper pressing protrusion 120 located on the flat surface portion of the paper feed roller 100.

When the rotating shaft 110 rotates at the above-mentioned predetermined timing, the top one of the recording media stacked on the intermediate plate 60 in a state in which no lifting or displacement occurs is performed. It comes into contact with the arc-shaped portion 100a and is sent out in the direction of arrow E with its rotation. When the uppermost recording medium 140 starts to be fed, both ends of the leading end of the uppermost recording medium 140 come off the leading end 90a of the separation claw 90, and the second and subsequent recording media 140 from the top.
Separated from Since the recording medium 140 does not rise or shift, the recording medium 140 is smoothly fed without being skewed when being fed.

In the above-described example, a case in which a half-moon shape is used as the paper holding projection 120 has been described. However, the present invention is not limited to the half-moon shape, and any shape may be used as long as it can prevent the recording medium 140 from lifting or shifting. Such a shape may be used. Also,
The position where the paper holding protrusion 120 is fixed is determined by the feed roller 1.
00 is not limited to the portion opposite to the arcuate portion 100a, and may be any position on the rotation axis.
Any position may be used as long as it can prevent the floating or displacement of zero. Therefore, it is not necessary to fix the paper holding projection 120 to the rotating shaft 110. However, it is preferable that the portion of the paper pressing protrusion 120 that contacts the recording medium 140 has a smooth shape because the recording medium 140 is not damaged.

[0037]

As described above, according to the paper feeder of the present invention, the middle plate is pushed up swiftly, and the recording medium loaded on the middle plate rises or shifts from the loaded position. Even if an attempt is made, the recording medium is pressed against the paper pressing projections, so that the recording medium is prevented from being lifted or displaced, and is prevented from being skewed when being fed, so that the recording medium is fed smoothly.

Here, when a pair of separation claws for pressing both ends of a portion of the recording medium loaded on the middle plate located on the other side of the middle plate from above are provided, the recording medium is loaded on the middle plate. When the uppermost recording medium of the recording medium starts to be sent out, only both end portions of the leading end of the uppermost recording medium come off the separation claw, and are separated from the second and subsequent recording media from the top. For this reason, double feeding of the recording medium can be reliably prevented.

In the case where the paper feed roller is a pair of the recording media stacked on the middle plate and which comes into contact with a portion between the pair of separation claws, the recording medium is sent out by the two paper feed rollers. Therefore, skewing can be prevented more reliably.

Further, when the paper pressing projection is located above the portion between the pair of separation claws of the recording medium stacked on the middle plate, the portion of the recording medium that is easily lifted can be pressed. Therefore, skewing can be prevented even more reliably.

Further, when the paper press projection comes into contact with the recording medium when the recording medium loaded on the middle plate jumps up, the paper feed roller and the paper press projection can be integrally formed. It can be manufactured at relatively low cost and has a simple configuration.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating an appearance of a copying machine in which an embodiment of a sheet feeding device according to the present invention is incorporated.

FIG. 2 is a schematic diagram showing an outline of an internal structure of the copying machine shown in FIG. 1;

FIG. 3 is a perspective view showing the universal cassette with the middle plate lowered.

FIG. 4 is a perspective view showing the universal cassette with the middle plate raised.

FIG. 5 is an enlarged plan view showing a middle plate of the universal cassette in a state where the middle plate is raised and a portion in the vicinity thereof;

FIG. 6 is a perspective view illustrating a sheet feeding roller and a portion near the sheet feeding roller.

FIG. 7 is a front view of the paper feed roller of FIG. 6;

FIG. 8 is an enlarged perspective view showing one of two paper feed rollers.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Copier 60 Middle board 66 Other side part of middle board 90 Separation claw 100 Feed roller 100a Arc part of feed roller 110 Rotation axis (feed roller axis) 120 Paper press protrusion

Claims (5)

[Claims] 1. A cassette tub having a rectangular bottom wall and an open top surface, a side extending in a predetermined direction is located near the bottom wall, and the predetermined direction is opposite to the one side. A cassette tray having a middle plate on which a plurality of recording media are stacked, wherein the other side extending toward the bottom wall is inclined with respect to the bottom wall by coming and going from the bottom wall. In an image forming apparatus for forming an image on a recording medium, a sheet feeding unit that feeds a plurality of recording media stacked on the middle plate one by one in a feeding direction from the one side of the middle plate to the other side. In the device, extending in the predetermined direction above the other side of the middle plate,
A feed roller shaft that rotates around a longitudinal direction, a half-moon-shaped feed roller that is coaxially fixed to the feed roller shaft, and rotates with the rotation of the feed roller shaft, and the feed roller A paper holding projection fixed to a portion of the shaft opposite to a side where the arc portion of the paper feed roller is located, the paper holding protrusion pressing the recording medium loaded on the intermediate plate from above; Paper feeder. 2. A printing apparatus according to claim 1, further comprising a pair of separation claws for pressing both end portions of a portion of the recording medium loaded on the middle plate located at the other side of the middle plate from above. 2. The paper feeding device according to 1. 3. The paper feeding roller according to claim 2, wherein the paper feed roller is a pair of recording media stacked on the middle plate, the pair being in contact with a portion between the pair of separation claws. Paper feeder. 4. The paper holding projection according to claim 3, wherein the paper pressing projection is located above a portion between the pair of separation claws of the recording medium stacked on the middle plate. Paper feeder. 5. The paper holding projection according to claim 4, wherein the paper holding projection comes into contact with the recording medium when the recording medium loaded on the middle plate jumps up.
A paper feeder according to claim 1.