JP3337514B2 - 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 provided in, for example, an electrophotographic apparatus.

[0002]

2. Description of the Related Art There is a paper feeder of this type which is provided with a tray at an inner bottom of a paper feed cassette, and stores about 500 sheets on the tray.

The above-mentioned tray is gradually lifted by a dedicated elevator mechanism as the paper is fed and decreased, and the uppermost paper is always set at a fixed position and taken out by a pickup roller.

[0004] That is, when the sheet feeding operation starts, the elevator motor rotates, and the elevator arm rises via the gears of the elevator drive system. The elevator arm is located below the tray, which allows the tray to be lifted.

A sensor is attached to the pickup roller. The tray is lifted until the uppermost sheet comes into contact with the sensor, and when the sheet comes into contact with the sensor, the rotation of the elevator motor is stopped. .
As a result, the tray stops, and the paper is set at the paper feed position.

[0006]

However, conventionally, a dedicated elevator drive mechanism and a sensor are required to move the tray up and down, so that the structure is complicated, the cost is increased, and the apparatus is increased in size. However, there is a problem that the arrangement space is required widely. SUMMARY OF THE INVENTION It is an object of the present invention to provide a sheet feeding device that can set the top sheet at a sheet feeding position with a simple configuration.

[0007]

According to a first aspect of the present invention, there is provided a storage unit for storing sheets in a stacked state, and a mounting member provided in the storage unit for mounting the sheets. The sheet comes out of contact with the uppermost sheet of the laminated sheet placed on the placing member, and the sheet moves by reducing the number of sheets.
An unloading means for setting the amount of movement to a position of the uppermost sheet when half the number of sheets that can be stored in the storage unit is stored in the storage unit; and the weight of the paper of the half of the number of housing can be upper limit number of sheets and
An urging member for urging with a balancing urging force.

[0008]

[0009]

When the paper feeding operation is started, the take-out means comes into contact with the paper and the top paper is taken out. When the paper is gradually reduced by this removal, the take-out means tries to be displaced in the paper decreasing direction. At this time, the placing member is urged by the urging force of the urging member, and The displacement is regulated within a predetermined range. With this regulation,
The difference between the removal positions of the uppermost sheet and the lowermost sheet is minimized as much as possible, and the feeding distance is made constant to prevent variations in the feeding time.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in the drawings.

FIG. 2 shows the internal structure of the electronic copying machine. In FIG. 2, reference numeral 1 denotes a copying machine main body. A scanner 2 is provided on an upper side in the copying machine main body 1. The scanner 2 includes first and second carriages 5 and 6, on which a light source 7 and a first mirror 8 are disposed. The second carriage 6 is provided with second and third mirrors 9 and 10.

The light reflected by the third mirror 10 is sent to a photosensitive drum 11 to be described later via an optical system 31. The optical system 31 includes a lens 32, a fourth, a fifth, and a sixth
Mirrors 33, 34, 35.

A photosensitive drum 11 is rotatably provided substantially at the center of the copying machine body 1. Around the photosensitive drum 11, a charger 12, a developing device 13, a transfer charger 14 a, a peeling charger 1
4b, a cleaner 15 and a static eliminator 16 are provided.

In the drawing, reference numeral 26 denotes a transport path for transporting a sheet, and the transport path 26 sequentially passes along the transport direction of the sheet.
A registration roller pair 25, the transfer charger 14a,
A peeling charger 14b, a transport belt 27, a fixing roller pair 28, and a paper discharge roller pair 29 are provided.

A paper feeding device 18 to be described later is provided at a lower side in the copying machine main body 1.
Are taken out by a pick-up roller 21 as taking-out means.

The paper P picked up by the pickup rollers 21 is separated from the separation pad 22 by the separation pad 22.
The paper is separated and fed one by one by the rotation of the paper feed roller 23 pressed against the sheet. The paper P fed by the rotation of the paper feed roller 23 is transported along the transport path 24 and is sent to the registration roller pair 25.

A manual paper feeder 41 is provided on one side of the copying machine main body 1, and a paper discharge tray (not shown) for receiving the paper P discharged from the paper discharge roller pair 29 is provided on the other side. Is provided.

The paper manually fed from the manual paper feeder 41 is transported along a transport path 71. The pickup roller 76, the empty switch 72, the feed roller 74,
The separation pad 7 which is in contact with the lower portion of the feed roller 74
7 are provided.

When an image is formed, the first and second carriages 5 and 6 of the scanner 2 are moved to expose and scan the original set on the original glass table 36 with light from the light source 7. The reflected light from the original is reflected by first to third mirrors 8.
, And an image is formed on the photosensitive drum 11 via the optical system 31. The surface of the photosensitive drum 11 is charged by the charger 12, and an electrostatic latent image is formed by the image formation. The electrostatic latent image is sent to the developing device 13 by the rotation of the photosensitive drum 11, and is developed by supplying a developer. This developer image is transferred to a sheet P supplied from the sheet cassette 18 or the manual sheet feeding section 41, and the transfer charger 14
Transcribed by the action of a. Then, the sheet P on which the image has been transferred is separated from the photosensitive drum 11 by the action of the separation charger 14b, and then is conveyed by the conveyance belt 27 and sent to the fixing roller pair 28, where it is fixed. The paper is discharged onto a paper discharge tray (not shown) by the paper discharge roller 29.

When a sheet is manually inserted, the empty switch 72 is turned on and the pickup roller 76 is lowered while rotating, and the sheet is taken out. The paper is sent between the feed roller 74 and the separation pad 77, and is separated and sent out one by one.

As shown in FIGS. 1 and 3, the paper feeding device 18 has a paper feeding cassette 44 as a storage section, and a tray 45 as a mounting member is provided at an inner bottom of the paper feeding cassette 44. Is provided. On this tray 45, 500 sheets of paper P can be placed.

The pickup roller 21 as the above-described take-out means is brought into contact with the upper surface of the paper P placed on the tray 45. The pickup roller 21 is attached to a turning arm 51, and the turning arm 51 is turned by turning on and off an electromagnetic solenoid 53 to move the pickup roller 21 up and down.

That is, when the power supply to the electromagnetic solenoid 53 is stopped and demagnetized, the rotating arm 51 is rotated upward to move the pickup roller 21 upward, and the power is supplied to the electromagnetic solenoid 53 to excite. Then, the pickup roller 21 is lowered by its own weight and is brought into contact with the uppermost surface of the sheet P. On the other hand, a spring member 46 as an urging member is provided below the tray 45, and the spring member 46 pushes the tray 45 upward. In the present embodiment, the strength of the spring member 46 is designed to balance the weight of 250 sheets of A4 size paper. When the sheet P is A4 size and 250 or more sheets are placed, the tray 45 is lowered to the lowest point due to the weight of the sheet.

However, at the time of paper feeding, the electromagnetic solenoid 5
3, the rotation arm 51 is rotated downward, and the pickup roller 21 is lowered to abut on the uppermost surface of the paper P and rotate.

The paper P is taken out by the rotation of the pickup roller 21 and sent between the paper feed roller 23 and the separation pad 22. Here, the paper P is separated one by one and then fed to the registration roller 25 side in the copying machine main body 1 via the transport path 24.

By this paper feeding, the paper P decreases, and the paper P
Is less than 250 sheets, the tray 45 is lifted by the urging force of the spring 46 each time the sheet P decreases, and the position of the uppermost sheet P on the tray 45 is about 250 sheets. It does not drop below the position.

[0027] Note that if the paper P is A ₅ size, when accommodating 500 sheets of paper P in the paper feed cassette 44, the tray 45 by the weight of the sheet P, and down to the lowest point, the sheet feed At times, the pickup roller 21 descends to feed the uppermost sheet P into the main body 1.

However, since the weight of the A5 size is half that of the A4 size, the tray 45 is moved by the spring 46 each time the paper P is fed into the copying machine main body 1 and the number of sheets P is reduced to less than 500 sheets. The uppermost sheet position of the tray 45 is lifted and does not lower than the position of the uppermost sheet when 500 sheets are stored.

This situation will be described with reference to FIGS. First, FIG. 6 shows the inside of the paper feed cassette 44 when 500 sheets of A4 size paper P are stored, and FIG. 7 shows a half of the size of the paper P (A5 size in this example).
The state inside the paper feed cassette 44 when zero sheets are stored is shown.

As described above, in the present embodiment, the strength of the spring member 46 for pushing up the tray 45 is equivalent to the weight of 250 A4 size sheets, so that the A4 size sheet P ' When 500 sheets are stored in the tray 44, the tray 45 does not rise until the remaining amount of sheets reaches the weight corresponding to the urging force of the spring member 46, that is, until the number of sheets P reaches 250 sheets. When the pickup roller 21 descends, sheet feeding is performed (FIG. 6A,
(B)). When the number of sheets of paper P becomes 250 or less, the urging force of the spring member 46 exceeds the weight of the sheet of paper P.
5 is raised, and the paper P is brought into contact with the pickup roller 21 to feed paper (FIG. 6C). The pickup roller 21 has reached the lowermost position of the movable range when the number of sheets P reaches 250 (FIG. 6B), so that even if the number of sheets P reaches 250, the pickup roller 21 does not descend any further. It has become. When the paper P runs out, the position of the tray 45 pushed up by the spring material 46 matches the lowermost position of the pickup roller 21 (FIG. 6D). Next, a case where 500 sheets of A5 size paper are stored will be described.

When 500 sheets of A5 size paper are stored, the weight is equivalent to 250 sheets of A4 size paper, so that the tray 45 is at the lowest position (FIG. 7A). Since the urging force of the spring member 46 increases as the number of sheets P 'decreases, the tray 45 gradually rises.

Further, the pickup roller 21 is gradually lowered (FIG. 7B). When the sheet P 'runs out, as described above, the position of the tray 45 pushed up by the spring material 46 matches the lowermost position of the pickup roller 21 (FIG. 7C). .

As described above, the paper feed cassette 44 of this embodiment is
In order to feed all the stored sheets, the pickup roller 21 may be lowered to half the depth of the sheet cassette 44, and even if the number of sheets is small, the pickup roller 21 may reach the bottom of the sheet cassette 44. Since there is no need to descend, there is no large difference between the time required to take out the uppermost sheet and the lowermost sheet.

[0034]

As described above, according to the present invention, the tray is urged by the urging member, and the displacement of the uppermost sheet accompanying the removal of the stacked sheets is determined by maintaining the state of contact with the extracting means. Because it is restricted within the range, sensors and control mechanisms like elevator mechanisms are not required, and it can be structurally simplified,
In addition to the cost reduction, there is little change in the transport length due to the paper removal, and the paper can be fed accurately with a constant paper feed time.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a sheet feeding device according to an embodiment of the present invention.

FIG. 2 is an internal configuration diagram showing an electronic copier including the sheet feeding device of FIG. 1;

FIG. 3 is a perspective view showing a paper feed cassette of the paper feed device of FIG. 1;

FIG. 4 is an explanatory diagram showing a state in which A4 size paper is fed by the paper feeding device of FIG. 1;

FIG. 5 is an explanatory diagram showing a state in which A5 size paper is fed by the paper feeding device of FIG. 1;

FIG. 6 is an explanatory diagram showing a state inside a paper feed cassette when paper of A4 size is fed by the paper feed device of FIG. 1;

FIG. 7 is an explanatory diagram showing a state inside a paper feed cassette when paper of A5 size is fed by the paper feed device of FIG. 1;

[Explanation of symbols]

P: paper, 21: pickup roller (take-out means), 4
4 ... paper feed cassette (storage section), 45 ... tray (placement member), spring material (biasing member).

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B65H 1/18 310 B65H 1/12 310 G03G 15/00 516

Claims (2)

(57) [Claims] A storage unit configured to store sheets in a stacked state; a mounting member provided in the storage unit for mounting the paper; and a topmost one of the stacked sheets mounted on the mounting member. The sheet comes out of contact with the sheet, and the sheet moves as the sheet is reduced due to the ejection.The amount of movement is half of the upper limit number of sheets that can be stored in the storage section. And a biasing member for biasing the placement member with a biasing force that balances the weight of half the upper limit number of sheets that can be stored in the storage portion. And a sheet feeding device comprising: 2. The urging member comprises a spring member, and urges the paper so that the maximum displacement position of the paper removing means at the time of paper removal is equal to the position of the loading member when paper is not placed. The sheet feeding device according to claim 1, wherein