JPH0873056A - Paper feeding device and image forming device - Google Patents

Abstract

PURPOSE: To keep the paper feeding pressure nearly constant independently of the difference of the left quantity or the size of the sheet, and carry out the stable separative paper feed, as for a cassette having a specially large capacity. CONSTITUTION: As for a paper feeding pressure correcting means, a weight 17 is installed so as to be shiftable in the paper feeding direction on the undersurface of a middle plate 12b in a paper feeding cassette 1, and the weight 17 is automatically shifted according to the swing position of the middle plate 12b and the shiftable position of a side regulating plate for regulating the side of a sheet P. Therefore, according to the left quantity or the size of the sheet P, the turning moment of the middle plate 12b is varied, and the paper feeding pressure as the contact pressure to the paper feeding roller 3 of the sheet P due to a pressurizing spring 10 can be kept nearly constant automatically.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device that feeds sheets stacked and accommodated by pressing them against a rotary feeding member to separate them one by one, and an electrophotographic apparatus equipped with the sheet feeding device. The present invention relates to an image forming apparatus such as a copying machine or a laser beam printer.

[0002]

2. Description of the Related Art In recent years, image forming apparatuses such as copying machines equipped with a large-capacity paper deck have been widely available on the market. As the paper feeding cassette of a copying machine, a 500-sheet cassette capable of storing 500 sheets is becoming more common, from a cassette storing 250 sheets of transfer paper, and the number of troublesome paper supply tends to be reduced.

As a sheet feeding device provided in an image forming apparatus such as an electrophotographic copying machine or a laser beam printer, a sheet feeding cassette type having a separating claw is well known.

7A and 7B are views showing the structure of a conventional separating claw type sheet feeding device, in which FIG. 7A is a side view and FIG. 7B is a perspective view.

As shown in the figure, this sheet feeding device separates and feeds a transfer sheet (sheet) P stored in a sheet feeding cassette 1 by a separating claw 2 and a sheet feeding roller (rotary feeding body) 3. Has become. Tip corner of paper P (hereinafter, simply referred to as corner) P
1, the separation claw 2 is engaged, and the top paper P
The paper feed roller 3 is in contact with the top. When the paper feed roller 3 is rotated in the arrow A1 direction, a conveyance force is applied to the uppermost paper P in the arrow B1 direction by friction with the outer peripheral surface 3a of the paper feed roller 3. As a result, the central portion of the paper P moves in the direction of the arrow B1, but the corner P1 of the paper P is separated by the separation claw 2.
Since the movement in the direction of arrow B1 is blocked by the
A wavy loop L is formed slightly inside 1. And
When the paper P is further conveyed, the loop L grows,
The corner P1 laterally moves in the direction of the arrow B2, and finally this corner P
1 is disengaged from the separation claw 2, and only the uppermost paper P is separated and fed.

[0006]

However, since a large number of transfer sheets are stacked and stored in a large-capacity cassette, the intermediate plate 12 may differ depending on the remaining amount or size of the sheets.
The total weight of the transfer sheets stacked on top of it fluctuates greatly compared to a small capacity cassette.

Therefore, in the structure in which the tip end portion of the intermediate plate 12 is pushed upward by the pressure spring (pressurizing means) 10 with a constant force, the weight of the transfer sheet fluctuates, and the rotary shaft 12 of the intermediate plate 12 is changed.
Since the rotational moment at the pushing-up position of the pressure spring 10 around b is changed, the contact pressure between the transfer sheet P on the intermediate plate 12 and the sheet feeding roller 3 by the pressure spring 10, that is, the so-called sheet feeding pressure is changed. It changes a lot. If this paper feeding pressure is too low, the transfer paper and the paper feeding roller will slip and cause paper feeding failure. Conversely, if the paper feeding pressure is too high, multiple papers will be fed at one time. So-called double feeding occurs.

Therefore, the paper feeding pressure should be as constant as possible. For that purpose, in the case of a particularly large capacity cassette, the pressure spring 1 depends on the remaining amount or size of the paper on the intermediate plate 12.
It is necessary to adjust the paper feed pressure by replacing 0 with an appropriate spring force. However, this task is too cumbersome for the user and almost impossible.

Therefore, according to the present invention, particularly in a large-capacity cassette, the sheet feeding pressure can be kept substantially constant regardless of the remaining amount of sheets or the size of the sheet, and thereby stable separation and sheet feeding can be performed. An object of the present invention is to provide a sheet feeding device that can be used, and an image forming apparatus including the sheet feeding device.

[0010]

In order to achieve the above object, in the sheet feeding device according to the present invention, a sheet storage member (1) is provided.
A sheet feeding pressure correction unit for automatically keeping the sheet feeding pressure by the pressing unit (10) substantially constant is provided in accordance with the remaining amount or size of the sheets (P) stacked and stored on the inner plate (12). It was

As the sheet feeding pressure correcting means, for example, a weight (17) is provided on the back surface of the sheet stacking surface of the intermediate plate (12) by a guide member (14) so as to be movable in the sheet feeding direction, and Attach the weight (17) to the middle plate (12).
Weight moving means (15, S1, S) for automatically moving in accordance with the swinging position of the vehicle or the moving position of the side regulating plate (11).
2) is provided.

Further, in the image forming apparatus according to the present invention, the main body (100) is provided with the sheet feeding device (110, 11) having the above-mentioned configuration.
1) and an image forming unit (202) for forming an image on a sheet (P) fed from the sheet feeding device.

[0013]

According to the sheet feeding device having the above-mentioned structure, the sheets stacked and stored on the intermediate plate (12) of the sheet storing member (1) by the sheet feeding pressure correcting means (14, 15, 17, S1, S2). Since the paper feed pressure can be automatically kept substantially constant according to the remaining amount or size of (P), it is possible to prevent a paper feed failure and double feed, and perform stable separated paper feed.

As the paper feeding pressure correcting means, the intermediate plate (12)
A weight (17) movable in the sheet feeding direction is provided on the back side of the sheet stacking surface of the sheet, and the weight (17) is moved according to the swing position of the middle plate (12) or the moving position of the side regulating plate (11). In this case, the rotational moment of the intermediate plate (12) is changed in accordance with the remaining amount or size of the sheet (P), and thereby the feeding pressure by the pressurizing means (10) is changed. It can be kept almost constant automatically.

Further, according to the image forming apparatus of the present invention, the sheet feeding device (11) having the above-mentioned structure is provided in the main body (100).
0, 111) always separate the sheets and feed them to the image forming unit (202), so that the reliability is improved.

The reference numerals in the above parentheses are for comparison with the drawings and do not limit the structure of the present invention.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. <Embodiment 1> FIGS. 1A and 1B are diagrams showing a main configuration of a sheet feeding device according to a first embodiment of the present invention. FIG. 1A is a perspective view of a sheet feeding cassette (sheet accommodating member), and FIG. It is a perspective view of a side regulation plate movement adjusting means of the paper cassette. Also, FIG.
FIG. 3 is a front sectional view of the same paper feeding device. 1 and 2, the same components as those of the conventional example shown in FIG. 7 are designated by the same reference numerals.

As shown in the figure, a pair of movable side regulating plates 11 for regulating both sides of the transfer paper (sheet) P are arranged on both sides of the middle plate 12 in the paper feeding cassette 1. The side regulation plate 11 is moved and adjusted according to the paper size. As the movement adjusting means of the side regulating plate 11, for example, a gear mechanism as shown in FIG. 1B can be used. Then, the moving position of the side regulating plate 11,
That is, in order to detect the size of the paper P to be stored, the position detection sensor S1 is arranged on the inner surface of the cassette 1 on the paper feed side so as to detect the position of the side regulating plate 11 when the small size paper P2 is set. ing. At the same time, the detection plate 11a is formed by extending a part of the front side regulation plate 11 on the paper feed side to a position where the position detection sensor S1 can detect.

Further, the intermediate plate 12 swings up and down about the rotary shaft 12b. A position detection plate 12a is provided on the back side of the middle plate 12, and the position detection sensor S2 is correspondingly provided.
Is arranged. With this detection sensor S2, the middle plate 1
The swing position of 2, that is, the remaining amount of the paper P in the cassette can be detected.

Further, as a means for correcting the paper feed pressure, which is the contact pressure of the paper P on the middle plate 12 to the paper feed roller (rotary feeding body) 3, the paper placing surface (upper surface) of the middle plate 12 Back side (bottom side)
Further, a weight 17 movable in the sheet feeding direction, a guide member 14 formed of a lead screw for guiding the moving operation of the weight 17, and a drive motor (weight moving means) 15 for moving the weight 17 are provided. . By the forward / reverse operation of the drive motor 15, the weight 17 moves back and forth in the sheet feeding direction. Further, in order to detect the moving position of the weight 17, position detection sensors S3 and S4 are arranged at both ends of the moving range of the weight 17, respectively.

On the other hand, in order to control the drive motor 15 and the sensors arranged in the cassette 1, the main body 100 and the main body 100 are electrically connected to the end surface of the cassette 1 on the mounting side of the main body 100 of the image forming apparatus. A communication connector section 16 for performing general communication is provided. And the cassette 1 is the main body 1
Communication connector 16 of the cassette 1 when mounted on
Is connected to the communication connector section 13 on the main body 100 side,
The operation of electric parts in the cassette 1 is controlled and controlled by a control device (not shown) of the main body 100.

Next, the operation of the paper feed pressure correction means will be described.

First, the pressure spring 10 shown in FIG.
If the force for pushing up is set corresponding to a large size paper such as A3, A4 or B4 and such a paper type is stacked on the middle plate 12, the paper P can be fed in the same manner as the conventional paper feeding device. become. However, when a small size paper such as A5, B5 or a postcard is loaded on the middle plate 12,
The side regulating plate 11 is moved to a position that fits the size of the paper, and is finally set in the small size area as shown in the explanatory view of FIG. Therefore, the detection plate 11a of the side regulation plate 11 matches the detection position of the position detection sensor S1 arranged in the small size area.

As described above, when the cassette 1 on which the transfer sheets are stacked and stored is mounted on the main body 100, the position detection sensor S1 detects the detection plate 11a, and further the position detection sensor S2.
Thus, the position of the position detecting plate 12a of the middle plate 12 in the height direction is detected, and the respective detection results are transmitted to the control device of the main body 100. Then, the control device calculates an accurate sheet feed pressure correction amount based on the detection results of the sensors S1 and S2, and rotates the drive motor 15 in the cassette 1 based on the calculation result, whereby the middle plate The weight 17 on the lower surface of 12 is moved to correct the sheet feeding pressure.

The following is an actual calculation of the change in the sheet feeding pressure by the sheet feeding pressure correcting means.

That is, in the case of the balance of the rotational moment about the rotary shaft 12b of the intermediate plate 12, as shown in FIG. 2, the feeding pressure = pressing force × L + weight × L1 + paper weight × L2 It holds. For example, the weight 17 of the weight 17 = 250 g (gram), the weight of large size paper W = 500 g, the weight of small size paper W ′ = 25 g, L1 = 100 mm, L2 = 200 m
Assuming that m and L3 = 300 mm, when a large size sheet is stacked, the feed pressure A = pressing force × L + 250 × 100 + 500 × 20
0 When small size sheets are stacked, the feed pressure B = pressure × L + 250 × 100 + 250 × 200. Therefore, it is understood that the sheet feeding pressure B is much larger than the sheet feeding pressure A.

Therefore, when the weight 17 is moved to the position L3 by the above-mentioned paper feed pressure correcting means, the paper feed pressure C when the small size papers are stacked is: paper feed pressure C = pressurization pressure × L + 250 × 300 + 250 × 20
It becomes 0, and the feed pressure A and the feed pressure C can be set to the same value.

That is, according to the above-mentioned paper feeding device, the paper feeding pressure can be automatically adjusted according to the remaining amount or size of the paper and the paper feeding pressure can be kept substantially constant, whereby stable separation and feeding can be performed. You can do paper. <Embodiment 2> FIGS. 4A and 4B are views showing the construction of a sheet feeding device according to Embodiment 2 of the present invention, wherein FIG. 4A is a front sectional view and FIG.

As shown in the drawing, in this embodiment, a weight 17 and a guide member 14 for guiding the movement of the weight 17 are provided on the lower surface of the intermediate plate 12 as the sheet feeding pressure correcting means. The weight 17 is formed in a cylindrical shape, and one end of a T-shaped connecting rod 17a is connected to the central axis as a shaft portion, and the other end of the connecting rod 17a is linked to the moving block 17b. Further, a convex portion 21 that engages with the guide hole 20 provided in the side regulating plate 11 is formed on the upper surface of the moving block 17b.

The moving block 17b is interlocked with the movement adjusting operation of the side regulating plate 11 when the papers P having different sizes are stacked on the middle plate 12, and the block guiding groove 1a is provided at the bottom of the cassette 1. It is designed to move along.

In the above structure, for example, when a small size transfer paper is set on the intermediate plate 12, the side regulating plate 11 and the moving block 17 are set as shown in the operation explanatory view of FIG.
b and are moved in the direction of the arrow. Then, as shown in FIG. 4A, the moving block 17b and the connecting rod 17a are
Move from position to position B.

The intermediate plate 12 gradually rises as the transfer paper P decreases. At this time, the weight 17 also moves in the guide portion 14 so as to move away from the rotating shaft 12b of the intermediate plate 12 in conjunction with the operation thereof. That is, as shown in FIG. 4A, the weight 17 moves from the position C to the position D as the intermediate plate 12 rises and separates from the rotating shaft 12b of the intermediate plate 12,
The total rotation moment of the middle plate 12 around the rotation shaft 12b and the paper P on the middle plate 12 increases.

As a result, similarly to the first embodiment, the paper feed pressure can be automatically adjusted according to the remaining amount or size of the paper, and the paper feed pressure can be kept substantially constant, thereby achieving stable separation. Paper can be fed.

In the two embodiments 1 and 2 described above, the universal type paper feed cassette having the side regulating plate so as to accommodate the transfer sheets of various sizes is taken as an example. In the case of a dedicated type paper cassette that stores single-size transfer paper, it is configured to automatically adjust the paper feeding pressure according to the remaining amount of paper and keep the paper feeding pressure almost constant. be able to.

Next, an example of an image forming apparatus (copying machine) provided with the sheet feeding device described in the first or second embodiment will be described with reference to the sectional configuration diagram of FIG.

The image forming apparatus main body 100 includes a document placing table 206, a light source 207, a lens system 208, a paper feeding section 209,
The image forming unit 202 and the like are provided. The paper feeding unit 209 is provided with the above-described paper feeding devices 110 and 111 and a deck-type paper feeding device 112. Further, in the image forming unit 202, a cylindrical photoconductor 214, a developing device 215 containing toner, a transfer charger 216, a separation charger 217, a cleaner 218, a primary charger 219, etc. are arranged. Further, on the downstream side of the image forming unit 202,
Conveying device (conveying unit) 220, fixing device (fixing unit) 20
4, discharge rollers 205, and the like.

Next, the operation of this image forming apparatus will be described.

When a paper feed signal is output from a control device (not shown) provided in the main body 100, the paper feed devices 110, 111, 1 of the paper feed unit 209 are output according to the signal.
The transfer paper P from any one of 12 is reliably separated and fed one by one. On the other hand, from the light source 207 to the document table 20
The light reflected by the document D placed on the sheet 6 is
The photoconductor 214 is irradiated with light through the lens system 208. Here, since the photoconductor 214 is charged in advance by the primary charger 219, an electrostatic latent image is formed by irradiating light, and then a toner image is formed by the developing device 215.

Then, the paper P fed from the paper feed unit 209
The skew feeding is corrected by the registration roller 201, and the timing is adjusted to be sent to the image forming unit 202. In the image forming unit 202, the transfer charger 216
The toner image on the photoconductor 214 is transferred onto the paper P that has been sent to form an image, and the paper P after the transfer is separated by the separation charger 2
It is charged to the opposite polarity to the transfer charger 216 by 17 and separated from the photoconductor 214.

The separated paper P is conveyed to the fixing device 204 by the conveying device 220, and the unfixed transfer image on the paper P is permanently fixed by the fixing device 204. further,
The paper P on which the image is fixed is discharged from the main body 100 by the discharge roller 205.

[0041]

As described above in detail, according to the sheet feeding device of the present invention, the sheet feeding pressure is automatically adjusted according to the remaining amount or size of the sheet to keep the sheet feeding pressure substantially constant. It can be maintained, and thereby stable separated sheet feeding can be performed. Therefore, it is possible to always reliably separate and feed the stacked and stored sheets without the need to replace the pressure spring.

Further, in the image forming apparatus according to the present invention equipped with this sheet feeding device, the sheets are always separated and fed reliably, so that the reliability of the image forming apparatus is improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a main part configuration of a sheet feeding device according to a first embodiment of the present invention, in which (a) is a sheet feeding cassette (sheet storage member).
Is a perspective view of the side regulating plate movement adjusting means of the paper feed cassette.

FIG. 2 is a front sectional view of the same sheet feeding device.

FIG. 3 is an explanatory diagram illustrating a moving region of a side regulating plate of the same sheet feeding cassette.

4A and 4B are diagrams showing a configuration of a sheet feeding device according to a second embodiment of the invention, in which FIG. 4A is a front sectional view and FIG.

FIG. 5 is an operation explanatory diagram in the second embodiment.

FIG. 6 is a cross-sectional configuration diagram showing an example of an image forming apparatus (copier) according to the present invention.

7A and 7B are diagrams showing a configuration of a conventional separating claw type sheet feeding device, in which FIG. 7A is a side view and FIG. 7B is a perspective view.

[Explanation of symbols]

 1 Paper Feed Cassette (Sheet Storage Member) 3 Paper Feed Roller (Rotary Feeding Body) 10 Pressure Spring (Pressure Means) 11 Side Regulation Plate 12 Middle Plate 14 Guide Member 15 Drive Motor (Feed Pressure Correction Means) 17 Weight (Paper feeding pressure correcting means) S1, S2 Position detection sensor (paper feeding pressure correcting means) 100 Image forming apparatus main body 110, 111 Paper feeding device 202 Image forming unit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location G03G 15/00 516

Claims (4)

[Claims] 1. A sheet storage member and a rotary feeder are provided,
In the sheet storage member, a swingable middle plate for stacking sheets, a pressurizing means for urging the middle plate to press the sheet on the middle plate against the rotary feeding body, and the middle plate. A side regulating plate that adjusts its position according to the size of the upper sheet; and the pressing unit according to the remaining amount or size of the sheets stacked and stored on the middle plate of the sheet storing member. A sheet feeding device, which is provided with a sheet feeding pressure correcting unit that automatically keeps the sheet feeding pressure by the sheet feeding pressure substantially constant. 2. A weight provided on the back surface of the sheet stacking surface of the middle plate as the sheet feeding pressure correction means so as to be movable in a sheet feeding direction by a guide member, and the weight is oscillated by the middle plate. The sheet feeding device according to claim 1, further comprising a weight moving unit that automatically moves in accordance with a position or a moving position of the side regulating plate. 3. A sheet storage member and a rotary feeding body are provided,
The sheet storage member includes a swingable middle plate for stacking sheets, and a pressurizing unit for urging the middle plate to press the sheet on the middle plate to the rotary feeding body. The paper apparatus includes a paper feed pressure correction unit that automatically keeps the paper feed pressure of the pressurizing unit substantially constant according to the remaining amount of sheets stacked and stored on the middle plate of the sheet storage member. Paper feeder. 4. An image forming apparatus, comprising: the sheet feeding device according to claim 1; and an image forming unit that forms an image on a sheet fed from the sheet feeding device.