JP3222252B2 - Paper feeder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
It can be applied to copying machines, facsimile machines, readers, and the like. More specifically, the present invention relates to a sheet feeding device that rotates a sheet feeding roller and sequentially feeds stacked sheets stored in a sheet feeding cassette one by one.

[0002]

2. Description of the Related Art Conventionally, in a paper feeder of this type, a paper feed cassette 1 is attached to a printer main body, and a bottom plate 4 is pushed up by a lever 2 to raise the paper feed cassette 1 as shown in FIG. The feeding roller 3 is pushed up by the loading sheet S stored therein, the feeding roller 3 is pressed against the uppermost loading sheet S by its own weight, and the loading sheet S is sequentially rotated from the top by the rotation of the feeding roller 3. We sent out one by one.

[0003]

By the way, the stacked sheets S stored in the paper feed cassette 1 are of B5 size or A size.
If the sizes are different, such as one size, the weight of the sheet is different, and even if the sheets have the same size, the weight of the sheet differs between the thin sheet and the thick sheet. On the other hand, the feed roller 3
Because of its own weight, it always presses against the stacking sheet S with the same force.

For this reason, in the conventional paper feeder, if the weight of the paper feed roller 3 is set according to, for example, a heavy sheet,
In the case of a light sheet, the sheet becomes too heavy to cause double feeding of the sheet. On the other hand, if the weight of the sheet feed roller 3 is set according to the light sheet, the weight of the heavy sheet becomes insufficient and the sheet is not fed. There was a problem that occurred.

SUMMARY OF THE INVENTION It is an object of the present invention to press a sheet feed roller against a sheet with an optimum pressing force according to the weight of the sheet in the sheet feed cassette to prevent double feed or non-feed.

[0006]

According to the first aspect of the present invention, for example, as shown in the embodiment of FIG. 1, a paper feed cassette 20 is mounted, and the stacked sheets S stored in the paper feed cassette 20 are stored. In the sheet feeding device 18 which pushes up the sheet S by its own weight against the uppermost sheet S of the stacked sheets S and feeds the stacked sheets S one by one from the top by rotation of the sheet feeding roller 19, An elastic member, such as a leaf spring 35, having an elastic force corresponding to the weight of one of the stacked sheets S stored in the sheet feeding cassette 20 and pushing up the roller shaft 32 of the sheet feeding roller 19 with the elastic force, The paper feed cassette 20 is provided.

According to a second aspect of the present invention, as shown in the embodiment of FIG. 1, in the sheet feeding apparatus of the first aspect, a low friction member for reducing friction between the roller shaft 32 and the elastic member. A characteristic is that such a low friction member 36 is provided on one or both of the roller shaft 32 and the elastic member so that the plate spring 35 is provided.

According to a third aspect of the present invention, as shown in the embodiment of FIG. 5, for example, a sheet feeding cassette 20 is attached, a stacking sheet S stored in the sheet feeding cassette 20 is pushed up, and the stacking sheet S The paper feed roller 19 is pressed against the upper sheet S by its own weight, and the paper feed roller 18 rotates the paper feed roller 19 to feed the stacked sheets S one by one from the top. A magnetic force is generated according to the weight of one sheet S, and the magnet force pushes up the roller shaft 32 of the sheet feeding roller 19 with the magnetic force.
39 between the paper feed cassette 20 and the paper feed roller 19
It is characterized by being provided on both sides.

[0009]

According to the first aspect of the present invention, when the paper feed cassette 20 is mounted, the elastic member hits the roller shaft 32 of the paper feed roller 19 and pushes up, and pushes up the stacked sheets S stored in the paper feed cassette 20. Then, the feed roller 19 is pressed against the stacked sheets S with a pressing force corresponding to the weight of one of the stacked sheets S.

According to the second aspect, the sheet feeding roller 19
During the rotation, the friction between the roller shaft 32 and the elastic member is reduced by the low friction member 36.

According to the third aspect of the present invention, when the paper feed cassette 20 is attached, the roller shaft 32 of the paper feed roller 19 is pushed up by the magnetic force acting between the magnets 38 and 39, and the stack stored in the paper feed cassette 20. When the sheet S is pushed up, the feed roller 19 is pressed against the stacked sheet S with a pressing force corresponding to the weight of one sheet of the stacked sheet S.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 4 shows an overall schematic configuration of a laser printer including a sheet feeding device according to an embodiment of the present invention.

Reference numeral 10 in the figure denotes an apparatus main body. The apparatus main body 10 includes a photoconductor 11 substantially at the center, and a charger 12, an optical writer 13, and a developing device 1 around the photoconductor 11.
4. The transfer device 15 and the cleaning device 16 are arranged. With the rotation of the photoconductor 11 in the clockwise direction in the drawing, the surface of the photoconductor 11 is uniformly charged by the charger 12, and then a laser beam is irradiated by the optical writer 13 to form an electrostatic latent image. The toner adheres when passing through the developing unit 14 to form a visible image.

A paper feeding device 18 according to the present invention is provided on the lower right side of the apparatus main body 10 in the drawing. Then, the sheet feeding roller 19 is rotated to feed out the sheet S in the sheet feeding cassette 20, and the sheet S is abutted and stopped between the pair of registration rollers 22.
Then, the sheet S is conveyed between the photoconductor 11 and the transfer device 15 by rotating the registration roller 22 in synchronization with the rotation of the photoconductor 11, and the visible image on the surface of the photoconductor 11 is transferred to the sheet S. I do. Then, after the image is transferred, the sheet S is transported to the fixing device 23, and the fixing device 23
After the transfer image is fixed in the discharge section 2 through the discharge path 24,
Discharge to 5

On the other hand, after the image is transferred, the surface of the photoconductor 11 is cleaned by the cleaning device 16.

The above-described paper feeding device 18 having the paper feeding roller 19 and the paper feeding cassette 20 is constructed in detail as shown in FIG. In the device body 10,
The paper feed roller 19 is provided supported by a holder 30. The holder 30 has a flat plate shape, is elongated in a direction perpendicular to the sheet feeding direction indicated by an arrow, and is provided with arms 30a, 30a protruding from both ends thereof in the sheet feeding direction.
0a ・ 30a 保持
30b is provided. On the other hand, on both ends of the holder 30,
Pins 31 are provided to project in the length direction.

The feed rollers 19 are provided in a pair on the left and right sides near both ends of a roller shaft 32, and both ends of the roller shaft 32 are rotatably attached to the holding portions 30b. Then, the pins 31 of the holder 30 are attached to the left and right side plates (not shown) in the apparatus main body 10, and the holder 30 is provided rotatably around the pins 31. In addition,
By restricting the rotation of the holder 30 by a stopper (not shown), the paper feed roller 19 is
Is held in place.

On the other hand, the paper feed cassette 20 is a case having an upper surface opened, with the arrow direction being the front part in the paper feed direction, and being bent outward at right angles to the upper ends of the left and right side plates 20a.
0b is provided. A bottom plate 34 is pivotally mounted inside the paper feed cassette 20 by pins (not shown) so as to be vertically rotatable. Leaf springs 35 are provided on the left and right sides at the front of the sheet feeding cassette 20 in the sheet feeding direction.

Each of the leaf springs 35 has an elastic force corresponding to the weight of one of the stacked sheets S to be stored in the sheet cassette 20.
At the left and right ends of the front plate 20c. The intermediate portion of the leaf spring 35 is formed in a narrow plate shape, and the enlarged portion 35a is formed.
An inclined portion 35b and a flat portion 35c that are gradually raised from the upper edge of the sheet feeding cassette 20 toward the rear portion thereof are provided continuously, and provided to protrude above the left and right side plates 20a. The leaf spring 35
Of the flat portion 35c is bent downward at right angles from both sides of the flat portion 35c to guide portions 35d and 35.
In addition, a stepped portion 35f is provided in the outer guide portion 35e by bending the distal end portion into a crank shape. Then, the guide portion 35 is sandwiched between the upper ends of the left and right side plates 20a.
d · 35e is hung down to engage the step 35f with the flange 20b. Further, a low friction member 36 is attached on the flat portion 35c of the leaf spring 35.

In the paper feed cassette 20, a stack of sheets S of a predetermined size is placed on the bottom plate 34 and stored as shown. Then, as shown in FIG. 2, the front portion of the sheet feeding cassette 20 in the sheet feeding direction
Attach it from the direction of the arrow toward 0.

Then, the leaf spring 35 hits the roller shaft 32 of the paper feed roller 19 to push up the roller shaft 32, and at the same time, pushes the bottom plate 34 in the paper feed cassette 10 by appropriate lifting means such as the lever 2 shown in FIG. The sheet feed roller 19 is pushed up by the stacked sheets S. Then, the feed roller 19 is pressed against the uppermost sheet S of the stacked sheets S by its own weight. At this time, the sheet feeding pressure due to the weight of the sheet feeding roller 19 is reduced, and the stacked sheets S in the sheet feeding cassette 20 are reduced.
The sheet feed roller 19 is pressed against the stacked sheets S with a pressing force corresponding to the weight of one sheet. Then, the driving force from a driving source (not shown) is appropriately transmitted to the roller shaft 32 to rotate the sheet feeding roller 19, and the stacked sheets S are sent out one by one from the top by the rotation of the sheet feeding roller 19. At that time, the roller shaft 3
The friction between the plate 2 and the leaf spring 35 is reduced by the low friction member 36.

Thereafter, when changing the sheet size,
The paper feed cassette 20 is removed from the apparatus main body 10, and another paper feed cassette containing stacked sheets of different sizes is attached, although not shown. Then, the sheet feed roller is pushed up by the leaf spring provided in the other sheet feed cassette in the same manner as described above, and the sheet feed roller is stacked with a pressing force according to the weight of one sheet loaded in the sheet feed cassette. Press on the sheet.

In the illustrated embodiment, the low friction member 36 for reducing the friction between the roller shaft 32 of the sheet feeding roller 19 and the leaf spring 35 is provided only on the leaf spring 35 side. However, such a low friction member 36 may be provided only on the roller shaft 32 side, or may be provided on both the leaf spring 35 and the roller shaft 32.

In the illustrated embodiment described above, the sheet feeding roller 19 has an elastic force corresponding to the weight of one sheet loaded in the sheet feeding cassette 20 and the roller shaft 32 of the sheet feeding roller 19 is generated by the elastic force. To the sheet cassette 2
0. However, as shown in FIG. 5, a magnetic force is generated according to the weight of one sheet of the stacked sheets S stored in the sheet feeding cassette 20, and the magnets 38 and 39 which push up the roller shaft 32 of the sheet feeding roller 20 by the magnetic force are used. Alternatively, a configuration may be provided on both the paper feed cassette 20 side and the paper feed roller 19 side. That is, the magnets 38 are attached to both sides of the front of the sheet feeding cassette 20 in the sheet feeding direction, and the magnets 39 having the same polarity as the magnets 38 are attached to both ends of the roller shaft 32 of the sheet feeding roller 19.

When such a paper feed cassette 20 is attached to the apparatus main body 10, the roller shaft 32 of the paper feed roller 19 is pushed up by the magnetic force acting between the magnets 38 and 39, and is stored in the paper feed cassette 20. When the stacking sheet S is pushed up, the feed roller 19 is pressed against the stacking sheet S with a pressing force corresponding to the weight of one sheet of the stacking sheet S. Then, the driving force from a driving source (not shown) is transmitted to the roller shaft 32 to rotate the sheet feeding roller 19, and the stacked sheets S are sent out one by one from the top by the rotation of the sheet feeding roller 19.

[0026]

Therefore, according to the present invention, when the paper feed cassette is mounted, the roller shaft of the paper feed roller is set in the first aspect.
The sheet described in (1) is pushed up by an elastic member, and the sheet described in (3) is pushed up by a magnetic force acting between magnets, and fed by a pressing force according to the weight of one sheet stored in each sheet cassette. Since the rollers are pressed against the stacked sheets, sheets having different weights can be fed with optimal pressing forces, and double feed or non-feed of the sheets can be prevented.

According to the second aspect, since the friction between the roller shaft and the elastic member is reduced by the low friction member, the object of the present invention can be achieved by reducing the frictional resistance.

[Brief description of the drawings]

FIG. 1 is a perspective view of a sheet feeding roller and a sheet feeding cassette provided in a sheet feeding device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a state immediately before the sheet cassette is mounted.

FIG. 3 is a state diagram after the attachment.

FIG. 4 is a schematic configuration diagram of an entire internal mechanism of a laser printer including the paper feeding device.

FIG. 5 is a configuration diagram of a sheet feeding device according to another embodiment.

FIG. 6 is a schematic diagram of a conventional sheet feeding device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 18 Paper feeder 19 Paper feed roller 20 Paper feed cassette 32 Roller shaft 35 Leaf spring 38/39 Magnet S sheet

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B65H 3/06 340 B65H 1/26 314

Claims (3)

(57) [Claims] 1. A sheet feeding cassette is mounted, a stacking sheet to be stored in the sheet feeding cassette is pushed up, and a sheet feeding roller is pressed against the uppermost sheet of the sheet stack by its own weight. In a sheet feeding device that feeds stacked sheets one by one in order from the top, an elastic force corresponding to the weight of one sheet stored in the sheet feeding cassette is provided, and the elastic force pushes up a roller shaft of the sheet feeding roller. Elastic members,
A sheet feeding device provided in the sheet feeding cassette. 2. The sheet feeding device according to claim 1, wherein a low friction member for reducing friction between the roller shaft and the elastic member is provided on one or both of them. 3. A sheet feeding cassette is mounted, a stacking sheet to be stored in the sheet feeding cassette is pushed up, and a sheet feeding roller is pressed against the uppermost sheet of the stacking sheet by its own weight. In a sheet feeding device that feeds stacked sheets one by one in order from the top, a magnet that generates a magnetic force according to the weight of one sheet stored in the sheet feeding cassette and pushes up a roller shaft of the sheet feeding roller with the magnetic force, A sheet feeding device provided on both the sheet feeding cassette side and the sheet feeding roller side.