JP2001048362A - Sheet feeder and image forming device having same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent sheets, even with high stiffness, in the process of feeding from being delivered in a superimposed state to a pair of separation rollers. SOLUTION: A sheet feeder 32 includes a separation pad 13 disposed on the bottom of an inside plate 4 to provide sheet separation, a pair of separation rollers 11 and 12 for separating sheets S fed by a pickup roller 10, inside plate lifting means 5 for lifting and lowering the inside plate 4, and a separation pad support plate 20 for supporting the separation pad 13 for relative pivotal movement thereof to the inside plate 4. When the sheets S stacked in a cassette case 3 run short and the inside plate 4 is lifted accordingly, a depression of the leading edges of the sheets S by the trailing edge of an antecedently fed sheet S1 pivots the separation pad 13 so that its contact surface conforms to the flexure of the sheets S, which are protected against delivery in a superimposed state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a sheet feeding apparatus for feeding sheets and an image forming apparatus including the same, such as a copying machine or a printer.

[0002]

2. Description of the Related Art Image forming apparatuses such as copiers and printers
A predetermined amount of sheets stored in advance in a sheet storage unit such as a cassette is sequentially supplied to the image forming unit for each image forming process to form an image on the sheet.

Conventionally, as shown in FIG. 9, a sheet feeding apparatus 32 for feeding sheets to such an image forming apparatus includes a sheet cassette 1 for storing sheets S and a sheet S stored in the sheet cassette 1. And a pickup roller 10 that abuts on the uppermost surface of the sheet S with a predetermined pressing force to feed the sheet S, and that is fed by the pickup roller 10. And a separation roller pair including a feed roller 11 and a retard roller 12 for separating the separated sheet S.

The sheet cassette 1 has a cassette case 3 and a middle plate 4 which can be moved up and down by a middle plate elevating means 5 which can rotate freely. It has a supported shaft 6, a lifter plate 7 and a sector gear 8 integrally attached to the shaft 6, and a driving gear 9 which is driven to rotate by driving means (not shown). The driving means is controlled such that the highest position is within a predetermined height range. As a result, when the storage amount of the sheet S decreases, as shown in FIG. 10, the lifter plate 7 pushes up the middle plate 4 and the uppermost position of the sheet S is maintained in the predetermined height range. You.

[0005] Further, as shown in FIG.
A separation pad 13 is provided at a position facing the pickup roller 10 to prevent the sheets S from being sent out in a bundle when the storage amount of the sheets S is reduced.

[0006]

However, as shown in FIG. 12, the conventional sheet feeding apparatus, when a relatively rigid sheet S such as thick paper is fed, as shown in FIG. When the rear end pushes down the leading end of the sheet S stacked on the middle plate 4, the sheet S bends downward and the sheet S floats from the separation pad 13. The sheets S are sent out to the separation roller pairs 11 and 12 in a bundle state without being exhibited, and the sheets S in the bundle state are separated into the separation roller pairs 11 and 1.
2 could not be separated and could lead to jam.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to supply a sheet having a high rigidity to a separation roller pair even when a highly rigid sheet is fed. It is an object of the present invention to provide a sheet feeding apparatus capable of preventing the sheet from being fed and an image forming apparatus having the same.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a sheet loading plate for loading and supporting sheets, a separation pad disposed on a loading surface of the sheet loading plate, Sheet feeding means for sending out the sheets stacked on the sheet stacking plate, separating means for separating the sheets sent by the sheet feeding means one by one,
In the sheet feeding device having:
It is characterized in that a supporting means for movably supporting the sheet stacking plate is provided.

According to a second aspect of the present invention, the support means includes:
The separation pad is supported, and is attached to the sheet stacking plate so as to be rotatable around a rotation fulcrum arranged in a direction parallel to the stacking surface of the sheet stacking plate and substantially perpendicular to the sheet feeding direction. A pad support member.

According to a third aspect of the present invention, the pad support member is attached so as to rotate in a direction in which a downstream end in a sheet feeding direction is lowered.

According to a fourth aspect of the present invention, there is provided a stopper for regulating the pad supporting member in a state substantially parallel to the stacking surface of the sheet stacking plate, and the pad supporting member is directed to a position regulated by the stopper. And a biasing means for biasing the rotation.

According to a fifth aspect of the present invention, the urging means is a spring.

According to a sixth aspect of the present invention, the pad support member is provided at the downstream end of the sheet stacking plate in the sheet feeding direction, over the entire area of the stacked sheets in the width direction. It is characterized by.

[0014] According to a seventh aspect of the present invention, the support means includes:
It is characterized by comprising a flexible elastic member attached to the sheet stacking plate and capable of bending in a direction in which a downstream end in a sheet feeding direction is lowered.

According to an eighth aspect of the present invention, the separating means includes:
A feed roller that rotates in a sheet feeding direction; and a retard roller that rotates in a direction opposite to the sheet feeding direction, wherein the sheet stacking plate is rotatably provided, and a topmost one of the stacked sheets is provided. The lifting and lowering control is performed by the lifting and lowering means so that the position is substantially constant.

The ninth aspect of the present invention provides the first to eighth aspects.
A sheet supply apparatus according to any one of the above, and an image forming unit that forms an image on a sheet supplied from the sheet supply apparatus.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. The same or corresponding members as in the conventional example are denoted by the same reference numerals.

FIG. 1 shows a main body 30 of an image forming apparatus such as a printer, a copying machine, a facsimile, etc., and a sheet feeding device 32 disposed below the main body 30 for supplying sheets to the main body 30 of the image forming apparatus. The image forming apparatus main body 30 includes an image forming unit (image forming unit) 34 that forms an image on the sheet S supplied from the cassette case 3 of the sheet supply apparatus 32.
Is provided.

As described above, the sheet feeding device 32 is provided with the sheet feeding means 2 for feeding the sheet S, and the sheet feeding means 2 applies the sheet S stored in the sheet cassette 1 to a predetermined pressure. A pickup roller (sheet feeding means) 10 for abutting and feeding the sheet S, and separating means (feed roller 11 and retard roller 1) for separating the sheet S fed by the pickup roller 10
2) is provided. Further, a separation pad 13 formed of a member having a high friction coefficient is provided on a middle plate (sheet stacking plate) 4 accommodated in the cassette case 3 at a position facing the pickup roller 10 so that the stacked sheets are stacked. The sheet S is prevented from being sent out in a bundle state by the separation pad 13 when the amount of S decreases.

The middle plate 4 can be moved up and down by a middle plate elevating means 5. The middle plate elevating means 5 is rotatably supported by a support shaft 6 and integrated with the support shaft 6. It has a lifter plate 7, a sector gear 8, and a drive gear 9 attached,
Control is performed so that the uppermost position of the sheet S is within a predetermined height range. As a result, when the storage amount of the sheet S decreases, the lifter plate 7 pushes up the middle plate 4 to
Is maintained at a predetermined height.

[First Embodiment] As shown in FIG. 2 to FIG. 4, the middle plate 4 housed in the inner bottom of the cassette case 3 is provided with a middle plate 4 A separation pad support plate 20 rotatably supported by a rotation shaft (fulcrum) 21 disposed in a direction parallel to the sheet stacking surface 4a and substantially perpendicular to the sheet feeding direction is provided. Is attached to the upper surface of the separation pad support plate 20 at a position facing the pickup roller 10. When the storage amount of the sheets S stacked on the middle plate 4 is large, the separation pad 13 follows the sheet S so as to be in close contact with the lower surface of the sheet S by the load of the sheet S, and the separation pad support plate 20 Are positioned so as to be substantially parallel to the sheet stacking surface 4a of the intermediate plate 4 by a stopper 15 provided on the start end side of the intermediate plate 4.

On the other hand, as shown in FIG. 3, when the storage amount of the sheets S stacked on the middle plate 4 is reduced, the lifter plate 7 pushes up the middle plate 4 by the middle plate elevating means 5 so that the sheet is lifted. The uppermost position of S is maintained within a predetermined height range. In this state, when the leading end of the sheet S is pushed down by the trailing end of the previously fed sheet S1, the leading end of the separation pad support plate 20 rotates about the rotation shaft 21. By doing so, the contact surface of the separation pad 13 follows the lower surface of the sheet S according to the bending of the sheet S.

Here, in the present embodiment, as shown in FIG. 5, a spring (attachment) is applied to the separation pad support plate 20 in a direction to press the separation pad support plate 20 against the contact surface of the stopper 15. A biasing means) 25 is provided, and by applying an appropriate biasing force to the separation pad support plate 20 by the spring 25, the followability of the separation pad 13 to the lower surface of the sheet S is improved. Then, by appropriately selecting the spring constant of the spring 25 in accordance with the difference in rigidity caused by the material of the sheet S, it is possible to obtain the optimum following condition.

In the present embodiment, the case where the separation pad support plate 20 is provided only in the peripheral region of the separation pad 13 has been described. However, the present invention is not limited to this. For example, as shown in FIG. By providing the plate 4 rotatably over the entire area in the longitudinal direction (feeding direction), it is possible to prevent the sheet S from waving. Thereby, the followability of the separation pad 13 to the sheet S can be further improved, and the feeding direction of the sheet S to the separation roller pairs 11 and 12 can be stabilized.

[Second Embodiment] In this embodiment, as shown in FIG. 7, a separation pad support plate 20 'having a separation pad 13 adhered to the upper surface of the middle plate 4 is provided in a cantilevered state. Supported. This separation pad support plate 20 '
Is made of a flexible material such as a spring material, and the separation pad 13 can be bent integrally with the separation pad support plate 20 '.

Accordingly, when the leading end side of the sheet S is depressed downward by the already fed sheet S1 and is bent, as shown in FIG. 7, the separation pad support plate 20 'and the separation pad 13 Since the separation pad 13 can bend with the bending of the sheet S, the separation pad 13 can maintain the contact state with the sheet S even after the sheet S has bent. Accordingly, it is possible to prevent the sheets S from being sent out to the separation units 11 and 12 in a bundle state, thereby causing a jam. In this case, by setting the elastic modulus of the separation pad support plate 20 'to an appropriate value, it is possible to optimize the contact condition between the separation pad 13 and the sheet S for various sheets S having different rigidities. Become.

Next, based on FIG. 8, separating means (the feed roller 11 and the retard roller 1) for separating the sheet S will be described.
A copier 3 including a sheet supply device 32 having the above-described 2) and image forming means 34 for forming an image on a separated sheet.
0 will be described. In the copying machine 30, the sheet feeding device 32 is incorporated in a side deck 204, and the side deck 204 is provided on a side surface of the main body of the copying machine 30 on a transport path 203 upstream of the image forming unit 34 in the sheet transport direction. It is installed to face.

The side deck 204 is provided with a sheet stacking section 2 having an intermediate plate 4 on which sheets are stacked and provided at the bottom so as to be movable up and down.
07, a sheet feeding device 32 for separating and feeding a plurality of sheets on the middle plate 4 one by one from the upper surface, a housing 208 for accommodating the sheet stacking section 207 and the sheet feeding device 32, and a side deck. A guide rail 209 that slides on the side deck 204 when the copying machine 30 is installed on the copying machine 30.

The image forming means 34 includes a drum-shaped electrophotographic photosensitive member 215, a charger 216 for primarily charging the electrophotographic photosensitive member 215 around the photosensitive member 215, and a laser beam applied to form an electrostatic latent image. The developing unit 217 includes a developing unit 217 that forms a toner image by attaching toner to the electrophotographic photosensitive member 215, and a transfer unit 218 that transfers the toner image on the electrophotographic photosensitive member 215 to a sheet.

In the copying machine 30 having the above configuration, an image of a document (not shown) placed on the platen 219 is read by the optical reading means 219, and the electrophotographic photosensitive member 21 is read.
5, is formed as an electrostatic latent image, and is transferred to a sheet sent from the sheet supply device 32. The image formed on the sheet is fixed by the fixing unit 220, and the sheet on which the image is fixed is discharged to the tray 221.

[0031]

As described above, according to the present invention,
Moving the separation pad by providing support means for movably supporting the separation pad for separating sheets provided on the stacking surface of the sheet stacking plate accommodated in the sheet cassette with respect to the sheet stacking plate. Even if the sheet changes its position due to bending or the like, the separation pad can follow the change in the position of the sheet, so even when a highly rigid sheet such as cardboard is used, the function of the separation pad itself can be achieved. Is sufficiently exhibited, and it is possible to prevent the sheet from being sent out to the separating means in a bundle state to cause a jam or the like. Accordingly, it is possible to improve the reliability of the sheet feeding device and the image forming apparatus including the same.

[Brief description of the drawings]

FIG. 1 is a cross-sectional side view of an entire sheet supply apparatus according to the present invention and an image forming apparatus including the same.

FIG. 2 is a cross-sectional side view of a state where sheets are stored in a sheet cassette.

FIG. 3 is a cross-sectional side view showing a state where the amount of sheets stored in a sheet cassette is reduced and a middle plate is lifted.

FIG. 4 is a plan view of the sheet cassette.

FIG. 5 is a cross-sectional side view of another embodiment in which a middle plate is lifted.

FIG. 6 is a plan view of another embodiment of the sheet cassette.

FIG. 7 is a cross-sectional side view of another embodiment with the middle plate lifted.

FIG. 8 is a front sectional view of a copying machine having a sheet feeding device.

FIG. 9 is a cross-sectional side view of a conventional example in which sheets are stored in a sheet cassette.

FIG. 10 is a cross-sectional side view of a conventional example with a middle plate lifted.

FIG. 11 is a plan view of a conventional example of a sheet cassette.

FIG. 12 is a cross-sectional side view of a conventional example in a state where a middle plate is lifted.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 sheet cassette 2 sheet feeding means 3 cassette case 4 middle plate 4 a sheet loading surface 5 middle plate elevating means 10 pickup roller 11 feed roller 12 retard roller 13 separation pad 20, 20 ′ separation pad support plate 21 rotation axis 25 spring 30 image Forming device main body 32 Sheet feeding device 34 Image forming unit

Claims (9)

[Claims] 1. A sheet stacking plate for stacking and supporting sheets, a separation pad disposed on a stacking surface of the sheet stacking plate, a sheet feeding unit for feeding a sheet stacked on the sheet stacking plate, A separating unit that separates the sheets sent by the sheet feeding unit one by one, comprising: a supporting unit that movably supports the separation pad with respect to the sheet stacking plate. Characteristic sheet feeding device. 2. The support means supports the separation pad, and rotates around a rotation fulcrum arranged in a direction parallel to a stacking surface of the sheet stacking plate and substantially perpendicular to a sheet feeding direction. The sheet feeding device according to claim 1, further comprising a pad supporting member movably attached to the sheet stacking plate. 3. The sheet feeding apparatus according to claim 2, wherein the pad supporting member is attached such that a downstream end in a sheet feeding direction rotates in a downward direction. 4. A stopper for regulating the pad supporting member in a state substantially parallel to the stacking surface of the sheet stacking plate, and a biasing force for rotating the pad supporting member toward a position regulated by the stopper. The sheet feeding device according to claim 3, further comprising an urging unit. 5. The sheet feeding apparatus according to claim 4, wherein said urging means is a spring. 6. The pad supporting member is provided at the downstream end of the sheet stacking plate in the sheet feeding direction, over the entire area of the sheets to be stacked in the width direction. The sheet feeding device according to any one of claims 2 to 5. 7. The support means is formed of a flexible elastic member attached to the sheet stacking plate and capable of bending in a direction in which a downstream end in a sheet feeding direction is lowered. The sheet feeding device according to claim 1, wherein: 8. The separating means includes a feed roller rotating in a sheet feeding direction and a retard roller rotating in a direction opposite to the sheet feeding direction, and the sheet stacking plate is provided rotatably. The sheet feeding apparatus according to any one of claims 1 to 7, wherein lifting and lowering control is performed by lifting and lowering means so that the uppermost position of the stacked sheets is at a substantially constant position. 9. A sheet supply apparatus according to claim 1, further comprising: an image forming unit configured to form an image on a sheet supplied from the sheet supply apparatus. Image forming device.