JP2015013705A - Sheet supply device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a sheet supply device capable of being compatible with a wide variety of sheets and performing stable sheet supply; and an image forming apparatus including the sheet supply device.SOLUTION: A sheet supply device includes: stack means for stacking sheets; a first transport part for transporting, with a first transport force, a sheet stacked on the stack means; a second transport part for transporting, with a second transport force lower than the first transport force, the sheet transported by the first transport part; feed means, including the first and second transport parts, for feeding the sheet from the stack means; first separation means for separating the sheet fed with the first transport force of the first transport part; and second separation means, disposed downstream of the first separation means in a sheet transport path, for separating the sheet fed with the second transport force of the second transport part.

Description

  The present invention relates to a sheet supply apparatus that feeds stacked sheets used in an image forming apparatus such as a copying machine or a printer, and an image forming apparatus including the sheet supply apparatus.

2. Description of the Related Art Conventionally, as a paper feeding device, for example, as disclosed in Patent Document 1, a paper feeding device that feeds a sheet by rotating a paper feeding roller while pressing the upper surface of a stacked sheet is often used. .
Then, the fed sheet is separated by the first separation means having a separation claw, and the sheet that could not be separated by the first separation means is downstream of the sheet conveyance path from the first separation means. A sheet feeding apparatus that separates and conveys the sheet by a second separating unit disposed in the box is also used.

JP 2008-273701 A

  However, in recent years, image forming apparatuses are required to support a wide variety of sheets from thin paper to thick paper. In order to print on a wide variety of sheets, it is necessary to stably feed the sheets, but this causes problems described later.

  In order to cope with difficult-to-carry sheets such as thick paper, if the feeding force of the paper feed roller is set so as not to cause poor conveyance in the first separating means, it will be carried when a sheet that is easy to carry such as thin paper is fed. The power is too strong. For this reason, the second separating unit cannot cope with the conveying force, and the sheet that cannot be separated by the first separating unit cannot be separated into one sheet by the second separating unit. Then, there may be a phenomenon of double feeding in which a plurality of sheets are conveyed at a time.

  SUMMARY An advantage of some aspects of the invention is that it provides a sheet supply apparatus capable of handling a wide variety of sheets and capable of supplying a stable sheet, and an image forming apparatus including the sheet supply apparatus.

A placing means for placing the sheet, a first carrying portion for carrying the sheet placed on the placing means by the first carrying force, and a hollow portion, and the sheet carried by the first carrying portion, A feeding unit configured to feed a sheet from the placing unit, the second feeding unit configured to feed a second feeding force weaker than the first feeding force, the first feeding unit, and the second feeding unit. A first separation unit that separates the sheet fed by the first conveyance force of the first conveyance unit, and a downstream side of the sheet conveyance path from the first separation unit, and the second conveyance unit And a second separation unit that separates the sheet fed by the second conveying force.

  A first conveying unit configured to convey a sheet placed on the placing unit by a first conveying force; a member having a friction coefficient different from that of the first conveying unit; The sheet transported by the transport unit includes a second transport unit that transports the sheet with a second transport force that is weaker than the first transport force, the first transport unit, and the second transport unit. A sheet feeding unit configured to feed the sheet; a first separation unit configured to separate a sheet fed by the first conveyance force of the first conveyance unit; and a downstream side of the sheet conveyance path from the first separation unit. And a second separating unit that separates and conveys the sheet fed by the second conveying force of the second conveying unit.

  A placing means for placing the sheet; a first carrying portion for carrying the sheet placed on the placing means by a first carrying force; and a roller diameter different from the roller diameter of the first carrying portion, The apparatus includes a second conveyance unit that conveys a sheet conveyed by the first conveyance unit with a second conveyance force that is weaker than the first conveyance force, the first conveyance unit, and the second conveyance unit. Feeding means for feeding the sheet from the means, first separating means for separating the sheet fed by the first conveying force of the first conveying section, and a sheet conveying path from the first separating means. The sheet supply apparatus includes a second separation unit that is disposed on the downstream side and separates and conveys the sheet fed by the second conveyance force of the second conveyance unit.

  According to the present invention, separation suitable for a wide variety of sheets can be performed, and stable sheet feeding can be performed.

Cross section of image forming apparatus Perspective view of main part showing main part of paper feeding device Cross-sectional schematic diagram of the paper feeder Sectional schematic diagram of the paper feed roller in Embodiment 1 The figure which shows the change of the conveyance force in Example 1. FIG. Sectional schematic diagram of the paper feed roller in Embodiment 2 Sectional schematic diagram of the paper feed roller in Embodiment 3 Partial perspective view of a paper feed roller in Embodiment 4 Sectional schematic diagram of the paper feed roller in Example 4 Schematic diagram showing the rotation of a paper feed roller during paper feed in Example 4.

  Hereinafter, an image forming apparatus and a paper feeding apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  An image forming apparatus according to an embodiment of the present invention is an image forming apparatus such as a copying machine, a printer, a facsimile, and a composite device thereof. In the following, description will be made using an electrophotographic image forming apparatus.

[Example 1]
FIG. 1 is a cross-sectional view of the image forming apparatus of the present embodiment. In the image forming apparatus 100, the document pressing plate 104 is opened by the user, and the document is placed on the document table glass 106 with the image surface facing down. Then, the original cover 104 is closed by the user, and the original is pressed against the original table glass 106. When a user presses an operation button or the like on an operation panel (not shown), the image reading unit 108 moves rightward in FIG. The read image of the document is converted into a digital signal and transmitted to the laser scanner 110.

  The signal transmitted to the laser scanner 110 is converted into laser light, and is irradiated onto the photosensitive drum 112 via the scanner mirror 110a and the folding mirror 110b that rotate at high speed. The photosensitive drum 112 is uniformly charged by a charger 114, and an electrostatic latent image is formed on a portion irradiated with laser light. The electrostatic latent image is developed by a toner developer supplied from a developing roller 116 as a developer image forming unit, and becomes a visible toner image.

  On the other hand, the sheet is conveyed from the sheet cassette 102 in the direction of arrow E (sheet conveying direction) by the sheet feeding roller 118, and between the photosensitive drum 112 and the transfer roller 124 by the conveying roller pair 120 and the registration roller pair 122. Be transported. The transfer roller 124 transfers the toner image on the photosensitive drum 112 to the conveyed sheet. The sheet onto which the toner image has been transferred is conveyed to the fixing device 128 by the conveying device 126. The fixing device 128 heats and presses the sheet with the fixing roller 128a and the pressure roller 128b to fix the toner image on the sheet. The sheet on which the toner image is fixed is discharged to the paper discharge tray 132 by the paper discharge roller pair 130.

The configuration of the sheet feeding device of this embodiment will be described with reference to FIGS.
FIG. 2 is a perspective view illustrating a main part of the sheet feeding device according to the present exemplary embodiment.
The sheet P is placed on the paper feed cassette 102 as shown in FIG. The rear end of the sheet P is aligned by the rear end regulating plate 4.
Here, when the sheet P is viewed from the sheet conveyance direction, the upstream side is referred to as the rear end, and the downstream side is referred to as the front end.
A separation claw 5 as a first separation unit is provided on the downstream side of the sheet conveyance path of the sheet feeding roller 118, and regulates the upper surface of the uppermost portion of the stacked sheets P.

FIG. 3 is a cross-sectional view showing the main part of the paper feeding device of this embodiment.
The paper feed cassette 102 is provided with a placement plate 2 on which the sheet P is placed. The placement plate 2 has a rotation fulcrum 1a on the upstream side with respect to the sheet conveyance direction, and pushes the leading end of the sheet P upward by the urging force of the placement plate pressing spring 3.
A rear end regulating plate 4 is detachably mounted on the mounting plate 2. The rear end regulating plate 4 can change the mounting position according to the size of the sheet P to be placed.
Separating claws 5 that restrict the upper surface of the stacked sheets P are provided at both corners of the top end of the placed sheet P. The separation operation of the separation claw 5 will be described later. A paper feed roller 118 is provided at a position above the top end of the uppermost surface of the stacked sheets P.

  The paper feed roller 118 receives a driving force from a rotational driving source (not shown). The driving force is transmitted through the rotation shaft 101, rotates in the direction of arrow A in the figure, and comes into contact with the upper surface of the uppermost sheet of the stacked sheets P. Since the paper is regulated by the separation claw 5 having its leading corners locked, a certain resistance is generated against the feeding. At this time, since the coefficient of friction between the sheets is smaller than the resistance due to the regulation of the separation claw 5, only the uppermost sheet contacting the sheet feeding roller 118 slides with respect to the other sheets. Then, both corners of the leading edge of the uppermost sheet of the sheet P are bent and detached from the separation claw 5 and conveyed.

Further, on the downstream side of the separation claw 5, a separation roller 6 is disposed as a second separation unit that separates the fed sheets into one sheet and conveys the sheet to the image forming unit. The separation roller 6 includes a roller that conveys a sheet and a roller pair that applies a load to the conveyed sheet. As a result, a certain resistance is generated with respect to the feeding of the paper, but since the friction coefficient between the papers is small, only the uppermost paper that is in contact with the transport roller is transported while slipping with respect to the other paper. The
Since the plurality of stacked sheets P are separated by the separation claw 5 and then separated again by the separation roller 6, the sheets can be more effectively separated.

FIG. 4 is a schematic sectional view of the paper feed roller 118. A paper feed rubber 7, which is a high friction member, is attached to a rotary shaft 101 that receives a driving force from a rotational drive source (not shown).
The paper feed rubber 7 is provided with a first transport unit 7a and a second transport unit 7b.

  The first conveyance unit 7 a is set to a conveyance force (first conveyance force) necessary for the sheet to come off from the separation claw 5. By providing the hollow portion 11, the second conveying portion 7b has a smaller roller diameter than the first conveying portion 7a, so that the conveying force is reduced. This conveyance force is set to a conveyance force (second conveyance force) necessary for separating the sheets one by one by the separation roller 6.

  At this time, if the conveyance force for separating the sheet by the separation roller 6 is weaker than the conveyance force for removing the sheet from the separation claw 5, the first conveyance force is the second conveyance. It is set to be stronger than force. In this embodiment, since the conveyance force is changed by providing the hollow portion 11 in the paper feed rubber 7, it is possible to change the conveyance force without changing the conveyance amount.

  The relationship between the first transport force and the second transport force will be described with reference to FIG. FIG. 5 is a diagram illustrating a change in paper feeding / conveying force in the embodiment of the present invention. The vertical axis represents the strength of the conveyance force, and the horizontal axis represents the sheet leading edge position.

  The sheet fed with the first conveying force is separated and conveyed by the separation claw 5 as the first separation means. Thereafter, the conveyance force changes from the first conveyance force to the second conveyance force after the leading edge of the sheet passes through the separation claw 5 and reaches the separation roller 6 as the second separation unit. Then, the separation roller 6 performs separation and conveyance with the second conveyance force.

At this time, the first conveying force is strong enough to separate the thick paper with the separation claw 5 even in the case of thick paper feeding. The first transport force is set to be strong to cope with thick paper. However, in the case of thin paper feeding, even if the separation claw 5 cannot completely separate the second transport force, the second transport force is higher than the first transport force. Since it is weak, it has a conveying force that can be separated by the separation roller 6. For example, if the second conveying force is a conveying force that is 1 N weaker than the first conveying force, the conveying force is such that the separation roller 6 can separate the paper even when the separation claw 5 cannot complete the separation.
Thereby, since the conveyance force required for each separation claw 5 and separation roller 6 is set, a wide variety of sheets can be conveyed one by one, and stable paper feeding can be performed. .

[Example 2]
Next, a second embodiment of the present invention will be described with reference to FIG.
FIG. 6 is a schematic cross-sectional view of the paper feed roller 118 in this embodiment.
The description of the same configuration as in the previous embodiment will be omitted by using the same reference numerals, and only the difference from the previous embodiment will be described.

A paper feed rubber 8, which is a high friction member, is attached to a rotary shaft 101 that receives a driving force from a rotational drive source (not shown). The paper feed rubber 8 is provided with a large-diameter arc portion 8a as a first conveyance portion and a small-diameter arc portion 8b as a second conveyance portion.
The large-diameter arc portion 8a is set to a conveyance force (first conveyance force) necessary for the sheet to come off from the separation claw 5. The small-diameter arc portion 8b is set to a conveyance force (second conveyance force) necessary for separating the sheets one by one by the separation roller 6 because the roller diameter is set smaller than that of the large-diameter arc portion 8a. ing. At this time, the first conveying force is set to be stronger than the second conveying force. Thereby, since the conveyance force required for each separation claw 5 and separation roller 6 is set, a wide variety of sheets can be conveyed one by one, and stable paper feeding can be performed. .

[Example 3]
Next, a third embodiment of the present invention will be described with reference to FIG.
FIG. 7 is a schematic cross-sectional view of the paper feed roller 118 in this embodiment.
The description of the same configuration as in the previous embodiment will be omitted by using the same reference numerals, and only the difference from the previous embodiment will be described.

  A paper feed rubber 9 as a high friction member is attached to a rotary shaft 101 that receives a driving force from a rotational drive source (not shown).

The paper feed rubber 9 is provided with a first rubbing portion 9a and a second rubbing portion 9b.
The first rubbing portion 9 a is set to a frictional force (first conveying force) necessary for the sheet to come off from the separation claw 5. The second rubbing portion 9b is set to a frictional force (second conveying force) necessary for separating the sheets P one by one by the separation roller 6.

  At this time, the frictional force of the first rubbing portion 9a is set to be stronger than the frictional force of the second rubbing portion 9b. As long as the frictional force of the first rubbing portion 9a is stronger than the frictional force of the second rubbing portion 9b, another member may be used instead of rubber. In this embodiment, the conveying force is changed by changing the frictional force of the paper feed rubber 9.

If the conveying force is changed by changing the roller diameter, the conveying distance also changes. However, if the conveying force is changed by the frictional force, the conveying force can be changed while the conveying distance remains the same.
For this reason, when there is a restriction on the transport distance, it is preferable to change the transport force with a frictional force.

Thereby, since the conveyance force required for each separation claw 5 and separation roller 6 is set, a wide variety of sheets can be conveyed one by one, and stable paper feeding can be performed. .
[Example 4]
Next, a fourth embodiment of the present invention will be described with reference to FIGS.
FIG. 8 is a cross-sectional view of the paper feed roller in this embodiment.
FIG. 9 is a perspective view of the paper feed roller in this embodiment.
A feed roller collar 11 as a holding member into which a feed rubber 10 as a high friction member is fitted is attached to a rotary shaft 101 that receives a rotational drive force from a rotary drive source (not shown). The paper feed roller collar 11 is provided so as to be sandwiched between the side plates 101a and 101b. A pin 103a is inserted into a circular hole 101c provided in the side plates 101a and 101b. The pin 103a penetrates the paper feed roller collar 11 and is attached as a rotation fulcrum.

Further, the side plates 101a and 101b are provided with a long hole 101d on the opposite side of the circular hole 101c with the rotation shaft 101 interposed therebetween. The long hole 101 d is provided with a pin 103 b so as to penetrate the paper feed roller collar 11. The pin 103 b regulates the amount of rotation of the paper feed roller collar 11.
A spring 105 is attached between the paper feed roller collar 11 and the rotary shaft 101, one end of the spring 105 is held by the rotary shaft 101, and the other end urges the inner surface side of the paper feed roller collar 11. .

FIG. 10 is a schematic diagram showing the rotation of the rotating shaft 101 during paper feeding. When the rotational shaft 101 receives a rotational driving force from a rotational driving source (not shown), the paper feeding roller 118 rotates in the direction of arrow C in FIG.
As shown in (b), when the rotated sheet feeding roller 118 comes into contact with the stacked sheets P, the sheet is fed with the first conveying force set to the conveying force necessary for the sheet to come off from the separation claw 5. To send.
When the paper feeding roller 118 further rotates, the pin 103b moves in the direction of arrow F of the long hole 101d as shown in FIG. Rotate in the direction.

With this configuration, when the paper feed roller 118 rotates to a predetermined position, the roller diameter decreases, the conveyance force decreases, and the conveyance force necessary for separation by the separation roller 6 changes. Accordingly, a wide variety of sheets can be conveyed one by one, and stable paper feeding can be performed.
[Other examples]
In the above-described embodiment, the conveyance force is changed due to the configuration of the rubber layer of the paper feed roller 118, but the paper feed roller 118 is pressed against the placement plate 2 by controlling the placement plate pressing spring 3. It is also possible to change the conveying force by changing the force to be performed.

In this case, by providing a mechanism for moving the mounting plate 2 up and down by a motor, the mounting plate 2 is lowered at the timing when the separation claw 5 is removed, so that the force that the paper feed roller 118 presses against the mounting plate 2 is exerted. It can be changed to change the conveyance force.

2 loading plate 3 loading plate pressing spring 4 trailing edge regulating plate 5 separation claw 6 separation roller 7a first conveying portion 7b second conveying portion 12 hollow portion 102 sheet feeding cassette 118 sheet feeding roller P sheet

Claims (4)

A placing means for placing the sheet;
A first conveying unit that conveys the sheet placed on the placing means by a first conveying force;
A second conveyance unit that includes a hollow portion and conveys the sheet conveyed by the first conveyance unit with a second conveyance force weaker than the first conveyance force;
A feeding unit configured by the first conveying unit and the second conveying unit, and feeding the sheet from the placing unit;
First separation means for separating sheets fed by the first conveying force of the first conveying unit;
And a second separation unit disposed on the downstream side of the sheet conveyance path from the first separation unit and configured to separate the sheet fed by the second conveyance force of the second conveyance unit. apparatus. A placing means for placing the sheet;
A first conveying unit that conveys the sheet placed on the placing means by a first conveying force;
A second conveyance unit configured by a member having a friction coefficient different from that of the first conveyance unit, and conveys the sheet conveyed by the first conveyance unit with a second conveyance force weaker than the first conveyance force;
A feeding unit configured by the first conveying unit and the second conveying unit, and feeding the sheet from the placing unit;
First separation means for separating sheets fed by the first conveying force of the first conveying unit;
And a second separation unit that is disposed on the downstream side of the sheet conveyance path from the first separation unit and separates and conveys the sheet fed by the second conveyance force of the second conveyance unit. Sheet feeding device. A placing means for placing the sheet;
A first conveying unit that conveys the sheet placed on the placing means by a first conveying force;
A second conveyance unit configured to have a roller diameter different from the roller diameter of the first conveyance unit, and convey the sheet conveyed by the first conveyance unit with a second conveyance force weaker than the first conveyance force;
A feeding unit configured by the first conveying unit and the second conveying unit, and feeding the sheet from the placing unit;
First separation means for separating sheets fed by the first conveying force of the first conveying unit;
And a second separation unit that is disposed on the downstream side of the sheet conveyance path from the first separation unit and separates and conveys the sheet fed by the second conveyance force of the second conveyance unit. Sheet feeding device. Developer image forming means for forming a developer image;
Transfer means for transferring the formed developer image to a sheet;
Fixing means for heating the sheet on which the developer image has been transferred by the transfer means to fix the developer image on the sheet;
An image forming apparatus comprising: the sheet feeding device according to claim 1.

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