JP2697667B2 - Paper feeder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeder, and more particularly to an improvement in a paper feeder used in an image forming apparatus or the like.

[0002]

2. Description of the Related Art In this type of image forming apparatus, as a sheet separating apparatus for separating and feeding stacked sheets one by one, a pick roller generally formed of a half-moon rubber material or the like is used. The uppermost sheet is separated by only one sheet by utilizing the difference in friction coefficient between the sheet and the pick roller, and is conveyed in the direction of a predetermined conveying roller.

FIG. 7 is a schematic functional explanatory view showing a first example of a conventional paper feeding apparatus. In the figure, by rotating the pick roller 5 in the rotation direction C, the spring 9
And the uppermost sheet 7 of the stacked sheets 6
By the frictional force between the pick roller 5 and the paper 7
It is extruded in the direction of the conveying roller 8.

However, in such a method, only one sheet is conveyed due to the delicate balance of the frictional force between the top paper and the other papers. They will be transported at once.

As a technique for solving the above-mentioned disadvantages of the first conventional example shown in FIG. 7, a paper separating method (second conventional example) disclosed in Japanese Patent Application Laid-Open No. 2-169421 has been proposed.

A second prior art disclosed in Japanese Patent Application Laid-Open No. 2-169421 detects a sucker and an uppermost sheet surface which are provided so as to be able to come close to and separate from the uppermost sheet surface of sheets stacked in a sheet cassette. And a pressure reducing means for reducing the pressure in the suction cup to a negative pressure so that the suction cup absorbs the paper,
In a paper feeder including a lifting mechanism and a rotation mechanism for rotating the suction cup and the sensor, the suction cup is lowered by operation of the lifting mechanism until the sensor detects the top paper, and the sensor detects the top paper Then, the suction mechanism is rotated by the rotation mechanism until the suction cup comes into contact with the paper surface around the rotation center located behind the suction cup position with respect to the paper feeding direction, and the pressure reducing means is activated. Then, the paper is sucked by the suction cup, and then the suction cup is rotated in the opposite direction by the rotation mechanism from that state, and the suction cup is further raised by the lifting mechanism, thereby separating the paper in the paper feeding device. The way.

In the second prior art, however, the rotating operation of the rotating mechanism is performed at a stretch when the paper is separated. Therefore, before the paper is completely separated, the paper is transferred to the feed roller in the next stroke. Thus, there is a problem that sheets are multi-fed.
Due to this double feeding, for example, paper is wasted, and when the number of remaining papers in the paper cassette becomes several, all the remaining papers are turned up by the rotation of the suction cup, and the empty sensor operates. There was something.

In order to solve the above-mentioned problems of the second prior art, a paper separating method (third conventional example) disclosed in Japanese Patent Application Laid-Open No. 3-205235 has been proposed.

The third prior art discloses a sucker provided so as to be able to come into close contact with and separate from the uppermost paper surface of paper sheets stacked in a paper cassette, a sensor for detecting the uppermost paper surface,
A paper separating method for a paper feeder, comprising: a pressure reducing means for reducing the pressure in the suction cup to a negative pressure so that the suction cup absorbs paper; and a lifting mechanism and a rotation mechanism for lifting and rotating the suction cup and the sensor. Then, by operating the lifting mechanism, the suction cup is lowered until the sensor detects the top paper, and when the sensor detects the top paper, the suction cup is rotated around the rotation center by the rotation mechanism. In a paper separating method in a paper feeding device for operating a decompression unit to suck a sheet by a suction cup, and in that state, turning the suction cup in a direction opposite to the turning direction by the turning mechanism to separate the sheet,
When the suction cup once sucks the paper and turns by a small angle, the rotation of the suction cup is stopped, and the suction cup is temporarily held at that position and then rotated by a predetermined angle to separate the paper from the paper feeding device. And a paper separating method in the paper feeding device.

In addition to the first to third prior arts, a second,
As fourth to seventh conventional examples similar to the third conventional example, JP-A-2-169422, JP-A-3-147439,
Techniques disclosed in JP-A-3-293234 and JP-A-4-20437 can be mentioned.

[0011]

However, most of the above-mentioned second to seventh prior arts have complicated structures and operations, and in particular, the above-mentioned elevating mechanism and rotating mechanism are complicated, and the apparatus is increased in size. At the same time, the occurrence of troubles is high due to the complicated structure, and it has been difficult to realize a good paper separation function as expected.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances, and an object of the present invention is to provide a novel paper feeder which can eliminate the above-mentioned drawbacks inherent in the prior art. To provide.

[0013]

In order to achieve the above object, a paper feeder according to the present invention is provided with a plurality of suction cups on a peripheral surface of a pick roller, and the pressure inside these suction cups is reduced to a negative pressure. It has a configuration.

That is, in the present invention, a first cavity which always maintains a negative pressure inside the pick roller,
A plurality of second cavities formed in a circumferential portion of the pick roller, the plurality of second cavities being provided in communication with the plurality of cavities, and the suction cups being provided in the second cavities so as to selectively receive a negative pressure from the first cavities. Is arranged.

A cylinder formed of an elastic material and a cylinder having one end in contact with the cylinder and the suction cup connected to the other end are fitted into each of the second cavities, and the cylinder and the cylinder are separated from each other. It is arranged to slide confidentially in the second cavity.

Still further, a third cavity is formed in the longitudinal direction of the cylinder, and a hole substantially perpendicular to the third cavity is provided. By shortening the cylinder, the suction cup is formed by the hole of the cylinder and the third hole. A negative pressure is received from the first cavity via the cavity.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing an embodiment of the present invention, FIG. 2 is a schematic partial cross-sectional view illustrating the internal structure of a pick roller according to the present invention, and FIG. FIG. 4 is a sectional view of the pick roller cut along the line and viewed in the direction of the arrow.
(A) is a perspective view of a cylinder according to the present invention, FIG.
4C is a cross-sectional view of the cylinder according to the present invention, FIG. 4D is a plan view of the suction cup according to the present invention, FIG. 4E is a cross-sectional view of the suction cup according to the present invention, and FIG. FIG. 4 is a partial cross-sectional view for explaining the method.

Referring to FIGS. 1 to 5, reference numeral 1 denotes a pick roller (separation roller).
Shafts 11 and 12 rotatably mounted on bearings (not shown) provided on a paper feeding device main body (not shown) are fixed to both ends of the sheet feeding device (not shown) (see FIG. 3).

A cavity 13 is formed along the circumference of the pick roller 1, and the cavity 13 communicates with a cavity 12 a provided in the longitudinal direction of the shaft 12. The cavity 12a is connected to exhaust means (not shown).

As shown in FIG. 2, the circumferential surface of the pick roller 1 has a plurality (in the present embodiment, eight (8) as shown in FIG. , Only two are shown, and the others are abbreviated by alternate long and short dash lines.)) (Cavities) 14 are formed at equal intervals.
The cylinder 2 and the cylinder 3 shown in FIGS. 4A to 4C are fitted into these cavities 14. A suction cup 4 is attached to one end of the cylinder 3.

The cylinder 2 inserted into the innermost part of the cavity 14 of the pick roller 1 is made of an elastic, highly wear-resistant material.
For example, it is made of rubber, sponge, or the like. A spring material such as a coil spring can be used instead of the column 2. A cavity 31 is formed inside the cylinder 3 to be fitted next in the longitudinal direction, and a hole 32 communicating with the cavity 31 is provided in a direction substantially perpendicular to the cavity 31. A suction cup 4 made of, for example, rubber or the like is attached to the other end of the cylinder 3 as shown in the figure.

For example, an adhesive is applied to the upper surface 2a and the lower surface 2b of the cylinder 2 so that the cylinder 2 and the cylinder 3 can slide in the cavity 14 of the pick roller 1 while maintaining airtightness. .

The air pressure inside the cavity 13 of the pick roller 1 is always set to a negative pressure during operation. The present invention is configured as described above, and the operation of the present invention will be described below with reference to FIGS.

FIG. 1 is an explanatory view of the function of the present invention. The pick roller 1 is rotating in the direction of arrow B, and is arranged on the peripheral surface of the pick roller 1 at equal intervals via a cylinder 2 and a cylinder 3. The provided plurality of suction cups 4 rotate accordingly. When the suction cup 4 is in a free state, that is, before reaching the laminated paper 6, the hole 32 of the cylinder 3 is in the hermetically sliding portion of the block 16 as shown in FIG. I do not receive.

However, the paper 6 on which the suction cups 4 are stacked
Above, the suction cup 4 is pushed by the laminated paper 6 pressed by the spring 9, and as shown in FIG. 6, the cylinder 2 is shortened due to its elasticity, and the cylinder 3 is reduced by the When the hole 32 of the cylinder 3 is pushed toward the cavity 13 of the pick roller 1 by being pushed toward the center of the cylinder 1, the cavity 31 of the cylinder 3 is communicated with the cavity 13 in the pick roller 1. Since the air pressure in the cavity 13 is a negative pressure, the air in the cylinder 3 is sucked as shown by the arrow in FIG. 6, and as a result, the suction cup 4 sucks the uppermost sheet 7 of the laminated sheet 6. In this state, the pick roller 1 rotates in the direction of arrow B in FIG.
Rotates while sucking and adsorbing the sheet 7, and sends out the sheet 7 to supply it to the transport roller 8.

When the paper 6 is separated from the suction cup 5, the outside air enters the cavity 13 in a negative pressure state at a stretch.
Is weakened, the cylinder 3 moves outward by the elastic force of the cylinder 2, the cavity 31 of the cylinder 3 is cut off from the cavity 13, and the state returns to the state of FIG.

[0028]

As described above, according to the present invention,
With an extremely simple configuration, it is possible to feed one sheet at a time without fail, and a great effect can be expected without the disadvantages as in the prior art.

[Brief description of the drawings]

FIG. 1 is a schematic functional cross-sectional view illustrating an embodiment of a sheet feeding device according to the present invention.

FIG. 2 is a partial sectional view showing an internal structure of a pick roller main body according to the present invention.

FIG. 3 is a cross-sectional view showing a function of the pick roller according to the present invention, taken along line AA ′ of FIG. 1 and viewed in a direction of an arrow.

FIG. 4A is a perspective view of a cylinder according to the present invention,
(B) is a side sectional view of the cylinder according to the present invention, (c) is a front sectional view of the cylinder according to the present invention, (d) is a plan view of the suction cup according to the present invention, and (e) is the present invention. It is a side sectional view of such a suction cup.

FIG. 5 is a partial sectional view showing functions of the present invention.

FIG. 6 is a partial sectional view illustrating functions of the present invention.

FIG. 7 is a schematic explanatory diagram illustrating a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pick roller 11, 12 ... Shaft 13 ... Cavity 14 ... Cavity (hole) 15, 16 ... Block 2 ... Column 2a ... Top surface 2b ... Bottom surface 3 ... Cylinder 31 ... Cavity 32 ... Hole 4 ... Suction cup 5 ... Conventional pick roller 6 ... Laminated paper 7 ... Top paper 8 ... Conveying roller 9 ... Spring 10 ... Side plate

Claims (1)

(57) [Claims] 1. A first cavity rotatably supported in a conveying direction of sheets stacked in a sheet cassette in a conveying direction, and a first cavity inside which a negative pressure is always maintained, and a first cavity communicated with the first cavity. A pick roller provided with a plurality of second cavities formed in a circumferential portion, and suction cups respectively disposed in the second cavities so as to selectively receive a negative pressure from the first cavities. The suction cup is brought into close contact with the uppermost paper surface of the paper, and after suctioning the paper under negative pressure, the pick roller is rotated to separate the paper by turning the paper, and the leading end of the separated paper is transported. In the paper feeding device for feeding to a roller, a cylinder formed of an elastic material and a cylinder having one end in contact with the cylinder via an adhesive and the other end connected to the suction cup are fitted into the second cavities. And at the same time, connect the cylinder and the cylinder in the second cavity. Configured to slide confidential , and before
A third cavity is formed in the longitudinal direction of the cylinder and the third cavity is formed.
A hole that is substantially perpendicular to the cavity 3 is provided.
The suction cup is inserted through the cylindrical hole and the third cavity.
A sheet feeding device receiving a negative pressure from a first cavity .