JPH11255356A - Sheet feeding device and image forming device equipped with it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent wasteful consumption of energy and emission of noise while the structure remains simple. SOLUTION: When a sheet is to be attracted, a moving means 3 installed over a sheet stacking means with the possibility of elevating and sinking and holding a sheet attracting means 2 having a hollow part 2a with the bottom left open is sunk and the sheet attracting means 2 is abutted on the sheet P, and a suction force generating means 2b formed in a single piece with the sheet attracting means 2 consisting of an elastic member is deformed so as to decrease the volume of the hollow part 2a in the sheet attracting means 2. Then the moving means 3 is elevated, and the suction force generating means 2b is restored so as to return to the original volume of the hollow part 2a whose bottom opening 2a' is blocked by the sheet P in abutting, and at this time of restoration, a negative pressure is generated in the hollow part 2a, followed by the elevation of the sheet attracting means to 2 to which the sheet P is attached by this negative pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding apparatus and an image forming apparatus having the same, and more particularly to a sheet feeding apparatus in which sheets are suctioned one by one by sheet suction means.

[0002]

2. Description of the Related Art Conventionally, a copying machine, a printing machine, and other image forming apparatuses include a sheet feeding device of an air suction type as a sheet feeding device for a sheet such as a recording material or a thin plate material. Examples of such a sheet feeding device include, for example, Japanese Patent Application Laid-Open Nos.
No. 9417, Japanese Patent Application Laid-Open No. 6-127718, a suction pad as a sheet suction means, a moving means for supporting and moving the suction pad, and generating a negative pressure to apply a suction force to the suction pad. There is a configuration in which a sheet is fed by moving a suction pad that has sucked a sheet by a moving unit, the sheet being provided with a suction force generating means for applying the sheet.

[0003]

However, in such a conventional sheet feeding apparatus, a suction pressure generating means (suction pump) driven by an electric motor (motor) generates a negative pressure, and a suction pad (suction cup) is used. ), The generated negative pressure is connected by a tubular member made of a soft resin or the like to absorb the sheet, so that the structure becomes complicated as compared with a feeding device using a rubber roller. In addition, since a suction force generating means using a relatively expensive electric motor (motor) is used to generate a negative pressure, there is a problem that the cost is increased.

When a sheet made of a synthetic resin having little or no air permeability or a sheet having a filler or a surface coating agent such as glossy paper is used as a sheet, air enters into the suction pad through the sheet. Although it is easy to maintain the negative pressure in the suction pad because there is no, to continuously operate the suction pump, that is, to continuously generate a negative pressure, not only waste energy, There was a problem that noise also occurred.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and provides a sheet feeding apparatus having a simple structure and capable of preventing waste of energy and generation of noise, and an image forming apparatus having the same. The purpose is to provide.

[0006]

According to the present invention, there is provided a sheet feeding apparatus for sucking and feeding a sheet stacked on a sheet stacking means, comprising: a hollow portion having an open bottom portion; A sheet suction means having suction force generating means for generating a negative pressure in the hollow portion, and after holding the sheet suction means and contacting the sheet suction means with a sheet stacked on the sheet stacking means Moving means for moving the sheet suction means away from the sheet stacking means, wherein the suction force generating means changes the volume of the hollow portion with movement of the sheet suction means by the moving means. Thus, the sheet is attracted by generating the negative pressure.

Further, according to the present invention, the suction force generating means is formed integrally with the sheet suction means made of an elastic member, and the volume of the hollow portion is reduced by contacting the sheet by the movement of the moving means. The hollow portion is deformed and restored from the sheet stacking means to restore the volume of the hollow portion to the original volume. At the time of the restoration, a negative load is applied to the hollow portion whose bottom opening is closed by the abutted sheet. The pressure is generated.

In the present invention, the attraction force generating means is provided in the moving means, and a piston member which comes into contact with a sheet by the moving means to reduce the volume of the hollow portion, and a sheet stacking means by the moving means. When moving away from the seat, the piston member is moved to restore the volume of the hollow portion, and a bias is generated to generate a negative pressure in the hollow portion whose bottom opening is closed by the abutted sheet. And a member.

Further, the present invention includes negative pressure releasing means for releasing the negative pressure in the hollow portion generated by the suction force generating means after delivering the sucked sheet to the downstream conveying means. It is characterized by the following.

Further, the present invention is characterized in that the negative pressure releasing means releases the negative pressure by communicating the hollow portion with the atmosphere.

According to the present invention, there is provided a sheet feeding apparatus for sucking and feeding a sheet stacked on a sheet stacking means, and an image forming section for forming an image on the sheet fed by the sheet feeding apparatus. In the image forming apparatus provided, the sheet feeding device is the one according to any one of claims 1 to 5.

Further, as in the present invention, the sheet suction means having a hollow portion with an open bottom is held by the moving means, and at the time of sheet suction, the moving means is moved to bring the sheet suction means into contact with the sheet. At the same time, the suction force generating means of the sheet suction means is deformed so as to reduce the volume of the hollow portion of the sheet suction means. After that, the sheet suction means is moved away from the sheet stacking means by the moving means, and the suction force generating means is returned so that the volume of the hollow portion whose bottom opening is closed by the abutted sheet is restored. At the time of restoration, a negative pressure is generated in the hollow portion at the time of the restoration, and the sheet is sucked by the negative pressure.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view of a copying apparatus as an example of an image forming apparatus provided with a sheet feeding apparatus according to a first embodiment of the present invention. In FIG. It is. The copying apparatus 50 includes a paper cassette 55 as sheet stacking means on which recording paper P as a sheet is stacked. The recording paper P stacked in the paper cassette 55 is supplied by the sheet feeding device 1A. Paper roller pair 1
After being fed to the recording paper P, the recording paper P is conveyed to a process cartridge 52 as an image forming unit via a pair of registration rollers 63a and 63b having a function of correcting the inclination of the recording paper P.

The recording paper P on which an image has been formed by the process cartridge 52 is further transported by a transport belt 73.
The image is fixed to the fixing device 75 through a pre-fixing guide 74, and then discharged from a discharge port 78 downstream of the fixing device 75 and placed on a discharge tray 79.

Here, the process cartridge 52
Are the photosensitive drum 68, the developing sleeve 67, the photosensitive drum 6
8, a cleaning blade 69, a toner (not shown), a stirring mechanism thereof, and a waste toner container. A transfer charger 70 is provided at a position facing the photosensitive drum 68.

On the other hand, the transport belt 73 has rollers 71, 7
2 and rotatably supported by rollers 72
Are driven by driving means (not shown). The transport belt 73 is given an appropriate tension by a tensioner (not shown) of the roller 72.

The fixing device 75 comprises a heat roller 76 having a built-in heater and a pressure roller 77.
Thermal fixing of the toner printed on the recording paper P is performed in the nip portions 6, 77. The pressure roller 77 is pressed against the heat roller 76 by a spring (not shown).

In FIG. 1, reference numeral 80 denotes a platen glass on which a document is placed. Below the platen glass 80, an illumination lamp 81, an image forming lens 85, and mirrors 82, 8 are provided.
An optical system including 3, 84, and 86 is provided, and the optical system irradiates a predetermined position of the photosensitive drum 68 with reflected light 87 from the document.

Reference numeral 91 denotes a pressure plate which is disposed on the document table glass 80 so as to be openable and closable and presses the document appropriately.
Reference numeral 1 is provided with a pressure contact sheet 90 made of a sponge-like member having an appropriate hardness on the original contact surface side. Reference numeral 96 denotes a manual paper feed port, and the manual paper feed port 96 is used when recording paper which is difficult to feed from a cassette such as thick paper or thin paper is used. The recording paper from the manual paper feed port 96 is transported by rollers 97 and 98.

FIG. 2 shows the sheet feeding apparatus 1A.
FIG. 3 is a schematic perspective view of the sheet feeding apparatus.
FIG. 4 is a sectional view taken along line BB in FIG.

2 to 4, reference numeral 1 denotes a main frame of the sheet feeding apparatus 1A, and the following members constituting the sheet feeding apparatus 1A are fixed to the main frame 1.
Or it is engaged.

Reference numeral 2 denotes a pair (two) of suction pads serving as sheet suction means, and reference numeral 3 denotes swinging (up and down) above the paper cassette 55.
On the other hand, the suction pad 2 is rotatably held in one end portion within a predetermined range while swinging (downward) at the time of suction of the recording paper so that the suction pad 2 comes into contact with the recording paper P. A swing arm as a means.

Here, the suction pad 2 is made of an elastic member such as rubber and has a hollow portion 2a having an open bottom. The upper portion of the suction pad 2 has a so-called bellows structure. The bellows portion 2b, which is an example of the suction force generating means, is easily pressed by the swing arm 3 from above as described later. The hollow portion 2a is deformed so as to contract downward to reduce the volume of the hollow portion 2a. When the pressing force is released, the hollow portion 2a is restored to its original shape by the restoring force of the bellows.

After the bellows portion 2b is compressed and deformed to reduce the volume of the hollow portion 2a as described above, when the force is released to return to the original shape, the opening 2a 'of the hollow portion 2a is moved by the recording paper P. Therefore, a negative pressure is generated inside the hollow portion due to the restoring force of the bellows portion 2b, and both ends of the recording paper P in the feeding direction can be attracted by the negative pressure.

On the other hand, a projection 2c is provided on a side wall surface of the suction pad 2, and the projection 2c is provided on the main frame when the suction pad 2 moves in a recording paper conveying direction indicated by an arrow X as described later. 1 and is pressed by the pressing portion 1a which constitutes the negative pressure releasing means together with the projection 2c. And the projection 2c is in this way the pressing portion 1
a, the vicinity of the protrusion is deformed and the hollow portion 2a of the suction pad 2 communicates with the atmosphere, whereby the negative pressure in the hollow portion 2a is released and eliminated, and the suction paper of the suction pad 2 is released. It is supposed to be.

Incidentally, the pair of suction pads 2 and 2
Is held in the swing arm 3 in the width direction orthogonal to the recording paper feeding direction and at an interval that does not hinder the suction of the minimum width recording paper among the recording papers that can be used by the copying apparatus 50. Have been. In the present embodiment, the recording paper is held at an interval of about half the recording paper width of the minimum width recording paper.

On the other hand, the swing arm 3 is swingably supported by the moving table 5 via the pin 3a, and holds the suction pad 2 by a tension coil spring 7 attached to the moving table 5. The other end (hereinafter referred to as the other end)
3b is urged in a direction of lifting up, that is, a direction of bringing the suction pad 2 into contact with the recording paper P. Here, the tension coil spring 7 has a sufficient spring force to deform the bellows portion 2b of the suction pad 2 downward.

Further, the moving table 5 has a part of the bracket 5.
By engaging the groove portion 5a 'of "a" with a not-shown notch of the main frame 1, it is slidably held by the main frame 1 and recorded by a tension coil spring 6 having one end fixed to the main frame 1. The paper P is urged in the feeding direction.

Reference numeral 4 denotes a recording paper holder. The recording paper holder 4 is rotatably supported by the swing arm 3 via a pin 4a, and is urged downward by a compression spring 40 in the drawing.
Further, it is stopped at a predetermined position by a stopper 4b.

Reference numeral 8 denotes a drive shaft connected to a motor (not shown). The drive shaft 8 rotates the first cam 9 and the second cam 10. The second cam 1
Numeral 0 is for contacting the other end 3b of the swing arm 3 from above to swing the swing arm 3. Also, the first
The cam 9 comes into contact with the contact portion 5b, which is bent at the end (hereinafter referred to as the other end) of the movable base 5 opposite to the side to which the tension coil spring 6 is attached, from the inside. This is for moving the movable table 5 in parallel while resisting the movement.

On the other hand, reference numeral 20 denotes a separating claw.
Numeral 0 is for suppressing a plurality of sheets of recording paper P from being sucked up by the suction pad 2 and for separating only the uppermost sheet. It should be noted that the feed roller pair 15, 16 already described
Are for urging in a direction approaching each other by urging means (not shown) and driven by a motor (not shown) to convey the recording paper P. R indicates the rotation direction of the drive shaft 8, the first cam 9, and the second cam 10.

In the above configuration, FIGS. 3, 5 to 7
The operation of the present embodiment will be described with reference to FIG.

FIG. 3 shows a standby state before paper feeding. In this state, the largest portion of the radius of the second cam 10 is in contact with the other end 3b of the swing arm 3 from above,
As a result, the swing arm 3 is kept almost horizontal, and the suction pad 2 is separated from the recording paper P. In this state, the bellows portion 2b of the suction pad 2 is not pressed and deformed.

The first cam 9 has its largest radius in contact with the contact portion 5b of the moving base 5, so that the moving base 5 is stopped at the left end position of its movable range. .
Further, the recording paper presser 4 is urged downward by a compression spring 40, is stopped at a predetermined position by a stopper 4b, and is separated from the recording paper P.

FIG. 5 shows a state in which the suction pad 2 attempts to suck the recording paper P. In this state, the first cam 9 and the second cam 10 are moved together with the drive shaft 8 from the state shown in FIG.
Start to rotate in the direction. Here, by such rotation,
The smallest radius portion of the second cam 10 is the other end 3 of the swing arm 3.
b, the swing arm 3 swings in the direction of lowering the suction pad 2 side by the force of the tension coil spring 7. Then, by the swing of the swing arm 3, the suction pad 2 comes into pressure contact with the recording paper P while compressively deforming the bellows portion 2b.

At this time, the recording paper presser 4 is urged downward by the compression spring 40 to abut the recording paper P and press the recording paper P. At this time, the first cam 9
The largest part of the radius is still in contact with the contact portion 5b of the moving table 5, so that the moving table 5 is stopped at the left end position of its movable range.

FIG. 6 shows a state in which only the uppermost recording paper P 'among the attracted recording papers P is separated. In this state,
In the second cam 10, a portion having a radius intermediate between the maximum portion and the minimum portion of the radius abuts on the other end 3b of the swing arm 3,
As a result, the swing arm 3 returns from the state of FIG. 5 to a slightly horizontal state. With the movement of the swing arm 3, the suction pad 2 moves upward while restoring the compressed bellows portion 2b to its original shape.

When the bellows portion 2b tries to restore its original shape, a negative pressure is generated in the hollow portion 2a, and the uppermost recording paper P 'is adsorbed by the negative pressure. 2, the recording paper P 'can be pulled upward. The recording paper holder 4 is composed of a compression spring 4
The recording paper P 'is urged downward by 0, and contacts the uppermost recording paper P' to hold down the recording paper P '.

Here, the second sheet from the top has a weaker attraction force than the uppermost recording sheet P ', and is thus held down by the separation claw 20 and the recording sheet retainer 4 to the weaker attraction force. During this time, the rigidity of the recording paper overcomes, and there is also a frictional force due to the pressing force from the recording paper retainer 4, so that the second and subsequent sheets are separated from the uppermost recording paper P '. On the other hand, the first cam 9
The largest part of the radius is in contact with the contact portion 5b of the movable base 5 and stops at the left end position of the movable range.

FIG. 7 shows a state in which the sucked recording paper P ′ is sent out toward the pair of paper feed rollers 15 and 16.

In this state, the largest portion of the radius of the second cam 10 contacts the other end 3b of the swing arm 3, whereby the swing arm 3 returns to a substantially horizontal state. Further, since the first cam 9 has a portion having the smallest radius in contact with the moving table 5, the moving table 5 is moved in the arrow X direction by the spring force of the extension coil spring 6. By moving the movable table 5 in the direction indicated by the arrow X, the suction pad 2 can transfer the recording paper P ′ to the pair of rollers 15 and 16 without any trouble.

By the way, as described above, the roller pairs 15, 16
When the recording paper P 'is delivered to the
Is pressed by the claw 1a of the main frame 1, whereby the vicinity of the protrusion is deformed by a predetermined amount. When the vicinity of the projection is deformed in this manner, the hollow portion 2a communicates with the atmosphere as shown in the figure, and the air flows into the hollow portion as shown by an arrow A, and the negative pressure of the hollow portion 2a is reduced. Is canceled.

When the recording paper P 'is sent out toward the pair of rollers 15 and 16, the recording paper retainer 4 is stopped at a predetermined position similar to the position shown in FIG. Although there is contact, the pressing force is not applied, and the frictional force is extremely small, so that the conveyance of the recording paper does not interfere.

By the way, after this, the sheet feeding roller pair 15, 1
The recording paper P 'transferred to the pair 6 is guided by the paper guide plates 65 and 66 shown in FIG.
By 63b, it is transported to the process cartridge 52. On the other hand, the image information of the original (not shown) is illuminated by an illumination lamp 81 below the original platen glass 80, reflected by an imaging lens 85 and mirrors 82, 83, 84, and 86, and becomes reflected light 87. Irradiation is performed at 68 predetermined positions.

Then, the image formed on the photosensitive drum 68 is developed by the developing sleeve 67 and is transferred by the transfer charger 70 to the conveyed recording paper P ′.
Further, the recording paper P ′ is further transferred to the fixing device 75 by the transport belt 73.
Sent to Then, the toner printed on the recording paper P ′ is thermally fixed by the heat roller 76, and thereafter,
The sheet is placed on the discharge tray 79 via the discharge port 78, and the recording is completed.

As described above, by generating a negative pressure by compressive deformation and restoration of the bellows portion 2b, a conventional suction pump is not used, and an air path using a tube member or the like is not newly provided. Thus, the recording paper P can be adsorbed, whereby the configuration of the apparatus can be simplified and the cost can be reduced.

Further, by releasing the negative pressure after the recording paper P 'has been delivered to the roller pair 15 and 16, unnecessary suction force of the suction pad 2 can be prevented. Can be generated, and waste of energy and generation of noise can be prevented.

Next, a second embodiment of the present invention will be described.

FIG. 8 is a view for explaining the structure of the suction pad of the sheet feeding apparatus according to this embodiment. In FIG. 8, reference numeral 30A denotes suction force generating means. The suction force generating means 30A includes a cylinder 30 that engages with the suction pad 2 without air leakage, a seal member 33 that can smoothly rub against the inner surface of the cylinder 30 and maintain airtightness, and a sealing member 33. While holding and slidably engaging the cylinder 30, the piston (member) 31 rotatably held within a predetermined range by the swing arm 3 and the cylinder 30 are urged downward, and the sealing member 33 is The piston 31 is lifted by overcoming the frictional force, and the recording paper P
And a compression coil spring 32, which is an urging member capable of generating a suction force (negative pressure) sufficient to lift the spring.

As shown in FIG. 5 described above, when the swing arm 3 swings in the direction of lowering the suction pad 2 with the rotation of the first cam 9 and the second cam 10, the suction pad 2
Presses against the recording paper P, and thereafter the piston 31
As shown in (1), the compression coil spring 32 is compressed by the swing arm 3 and descends together with the seal member 33 to the vicinity of the lowermost portion of the cylinder 30. Thereby, the volume of the hollow portion 2a of the suction pad 2 is reduced.

Thereafter, when the swing arm 3 swings upward, the compressed coil spring 32 in the compressed state is restored by the spring force. Then, with the restoration of the compression coil spring 32,
First, with the suction pad 2 pressed against the recording paper P, only the cylinder 30 moves upward. As a result, a negative pressure is generated in the hollow part 2a, and the negative pressure causes the recording paper P to be suctioned. It can be lifted up with the pad 2.

The other structure and operation are the same as those of the first embodiment, including the negative pressure canceling means, and will not be described.

As described above, by generating a negative pressure by the suction force generating means 30A, the recording paper can be formed without using a conventional suction pump and without newly providing an air passage using a tube member or the like. P can be adsorbed, whereby the configuration of the apparatus can be simplified and the cost can be reduced.

The present invention is not limited to the first and second embodiments described above, and the negative pressure generating means in the suction pad may be of another configuration without departing from the gist of the present proposal. Good. For example, the suction pad 2 and the suction force generating means may be arranged side by side in the horizontal direction.

The number of the suction pads 2 is not limited to the number shown in the above embodiment, but may be increased or decreased according to the width or rigidity of the recording paper P. Further, the number of the swing arms 3 for holding and moving the suction pad 2 is not limited to the number shown in the above-described embodiment, and may be two or more in the entire apparatus according to various circumstances such as the width of the recording paper to be used. Good.

[0057]

As described above, according to the present invention, it is possible to generate a negative pressure in the hollow portion of the sheet adsorbing means with the movement of the moving means (downward and upward operations). It is not necessary to provide a power source such as a motor only to generate force), and the structure can be simplified. Further, since a negative pressure can be generated only when necessary, it is possible to prevent waste of energy and generation of noise.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a copying apparatus as an example of an image forming apparatus including a sheet feeding device according to a first embodiment of the present invention.

FIG. 2 is a schematic perspective view of the sheet feeding device.

FIG. 3 is a sectional view of the sheet feeding device taken along line AA.

FIG. 4 is a sectional view of the sheet feeding device taken along line BB.

FIG. 5 is a diagram showing a state when the sheet feeding device starts a recording paper suction operation.

FIG. 6 is a diagram showing a state in which only the uppermost recording paper is separated from the recording paper sucked by the recording paper suction operation.

FIG. 7 is a diagram showing a state in which the sucked recording paper is sent out to a pair of paper feed rollers.

FIG. 8 is a diagram illustrating a configuration of a suction pad of a sheet feeding device according to a second embodiment of the present invention.

FIG. 9 is a diagram showing a state when the sheet feeding device starts a recording paper suction operation.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1A sheet feeding device 1a claw 2 suction pad 2a hollow portion 2a 'opening 2b bellows portion 2c protrusion 3 swing arm 30A suction force generating means 31 piston 32 compression coil spring 50 copying device 55 paper cassette P, P' recording paper

Claims (6)

[Claims] 1. A sheet feeding apparatus for sucking and feeding sheets stacked on a sheet stacking means, wherein a hollow portion having a bottom opening and a negative pressure for sucking the sheet are generated in the hollow portion. A sheet suction means having suction force generating means for causing the sheet suction means to hold the sheet suction means and contact the sheet suction means with a sheet stacked on the sheet stacking means; Moving means for moving away from the stacking means, and generating the negative pressure by changing the volume of the hollow portion with the movement of the sheet suction means by the moving means. A sheet feeding device configured to adsorb a sheet. 2. The suction force generating means is integrally formed with the sheet suction means made of an elastic member, and is deformed so as to abut on a sheet by the movement of the moving means to reduce the volume of the hollow portion. By restoring from the sheet stacking means, the volume of the hollow portion is restored to the original volume, and at the time of the restoration, a negative pressure is generated in the hollow portion in which the opening at the bottom is closed by the abutted sheet. The sheet feeding device according to claim 1, wherein the sheet feeding device is configured to cause the sheet feeding. 3. The attraction force generating means is provided in the moving means, the piston member abutting on a sheet by the moving means to reduce the volume of the hollow portion, and when moving away from the sheet stacking means by the moving means. An urging member that generates a negative pressure in the hollow portion whose opening at the bottom is closed by the abutted sheet by moving the piston member to return the volume of the hollow portion to the original volume. The sheet feeding device according to claim 1, wherein the sheet feeding device is provided. 4. A negative pressure releasing means for releasing the negative pressure of the hollow portion generated by the suction force generating means after delivering the sucked sheet to a downstream conveying means. The sheet feeding device according to claim 1, wherein 5. The sheet feeding apparatus according to claim 4, wherein said negative pressure releasing means releases said negative pressure by communicating said hollow portion with the atmosphere. 6. An image forming apparatus comprising: a sheet feeding device that sucks and feeds a sheet stacked on a sheet stacking unit; and an image forming unit that forms an image on the sheet fed by the sheet feeding device. The image forming apparatus according to claim 1, wherein the sheet feeding device is the one according to claim 1.