JP3136360B2 - Electrophotographic apparatus and method for preventing paper from winding around photoconductor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus, and more particularly to a method for preventing a sheet from being wound around a photosensitive member, and an electrophotographic apparatus employing the method.

[0002]

2. Description of the Related Art As a known example of a conventional electrophotographic apparatus, as described in Japanese Patent Application Laid-Open No. 2-95668, a paper is curled by a combination of an elastic roller and a metal roller in a direction of peeling from a photosensitive member. In some cases, the paper is prevented from being wound around the photosensitive member.

[0003]

However, in the above-mentioned prior art, consideration is given to the winding of the paper around the photosensitive member due to the dripping when the leading end of the paper is cut, and the winding around the thin photosensitive member having low bending rigidity. Did not.

That is, the number of sheets to be cut at one time at the time of cutting, the problem of wrapping around the photoreceptor occurring at a frequency correlated with the number of sheets, and the curl of the printed paper due to the wrapping around the photoreceptor, There was a problem that lowering.

The present inventors have found that a major cause of paper wrapping around the photoreceptor occurs when a sag equivalent to the thickness of the leading end of the paper at the time of cutting the paper is in the direction of peeling from the photoreceptor. I found it. That is, when the leading edge of the sheet is attached in a direction in which the sheet is separated from the photoreceptor, a gap layer is formed between the sheet and the transfer belt. Wraps around the photoreceptor that comes into contact at the transfer section.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problem. In particular, in a system in which a sheet is conveyed by adsorbing a sheet on a transfer belt and transferring is performed, a dripping at a leading end of the sheet is removed and a photosensitive member is removed. An object of the present invention is to provide an electrophotographic apparatus in which paper is not wrapped around a paper, and a method therefor.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a paper feeder for separating and feeding stacked paper sheets one by one, and a dielectric for electrostatically attracting and transporting the stacked paper sheets. An endless transfer belt, a pulley for driving the transfer belt, at least one pulley for stretching the transfer belt, an electrostatic latent image corresponding to print information, and electrostatic attraction on the electrostatic latent image To transfer the toner image on the photoreceptor to a sheet being conveyed by the transfer belt, the sheet is held in contact between the photoreceptor and the transfer belt. An electrophotographic apparatus comprising a transfer section, wherein a means for slightly bending the leading end of the sheet in the direction of the photoconductor is provided between the sheet feeding device and the transfer section. is there.

A supporting portion for supporting the leading end of the sheet, a fixing portion having a rounded corner in contact with the leading end of the sheet, between the sheet feeding device and the transfer portion; A moving portion for bending the paper leading end portion in the gap with the fixed portion toward the photoreceptor by moving with a predetermined gap from the portion, and a paper leading end bending means comprising: Is what you do.

Further, the stacked sheets are separated and fed one by one, and the sheets are electrostatically attracted and conveyed by an endless transfer belt made of a dielectric material, and an electrostatic latent image corresponding to print information and the electrostatic latent image are conveyed. A toner image on the photoconductor is conveyed by the transfer belt at a transfer section in which the transfer sheet is in contact with a photoconductor holding toner electrostatically adsorbed on the electrostatic latent image with the transfer belt therebetween. Of the electrophotographic device to transfer to the paper
In the method for preventing the paper from being wound around the photoconductor, the leading end of the paper conveyed to the transfer unit is slightly bent in the direction of the photoconductor.

[0010]

According to the above construction, the leading end of the sheet conveyed to the transfer section can be slightly bent in the direction of the photoreceptor, so that when the sheet is sandwiched between the photoreceptor and the transfer belt, the sheet and the transfer belt can be folded. No void layer is formed between them. Therefore, works effectively electrostatic adsorption of the transfer belt, it is never wound around the photoconductor sheet.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of an electrophotographic apparatus showing one embodiment of the present invention. The sheets 4 accumulated in the hopper 2 are separated and fed one by one, and are conveyed to the sheet leading end bending means 6. The conveying roller 8 conveys the sheet 4 to the transfer belt 10, and then the transfer belt 10 conveys the sheet 4 to a transfer section where the toner on the photosensitive drum 12 is transferred. The toner image on the photosensitive drum 12 is visualized by the developing device 14. A transfer corotron 16 is provided on the back side of the transfer belt 10 facing the photosensitive drum 12.
Are disposed, and the toner image on the photosensitive drum 12 is electrostatically attracted to the paper 4. Thereafter, the sheet 4 is transported to the fixing device 18 and the toner image is fixed on the sheet 4. The sheet 4 after the fixing is carried out to the output tray by the carry-out roller 20. In addition, the apparatus of this embodiment is provided with an optical unit 22 for displaying an image on the photosensitive drum 12, a cleaner 24 for cleaning residual toner on the photosensitive drum 12, and the like.

Here, the situation when the leading end of the sheet 4 passes through the transfer unit in the conventional electrophotographic apparatus will be described with reference to FIGS. 2 and 3. FIG. Because cut paper is cut from continuous paper by a cutting machine and manufactured, the sharpness of the cutting machine,
Depending on the number of sheets at the time of cutting, sags having different sizes like the leading end of the sheet 4 in FIG. Due to the effect of this sagging, a gap layer 26 is formed between the transfer belt 10 and the paper 4.
Occurs, where a discharge occurs and the charge is removed. As a result,
The leading end of the sheet 4 is attracted to the photosensitive drum 12, and the sheet 4 is attracted to the photosensitive drum 12 as shown in FIG. The sag is large and is about 1.5 times the thickness of the sheet, and the size of the sag is determined in one direction and at a period corresponding to the number of sheets at the time of cutting.

In order to eliminate the effect of the sag in the transfer portion and prevent the sheet 4 from winding around the photosensitive drum 12, it is preferable to bend the sheet in the direction opposite to the sag, that is, to fold the leading end of the sheet toward the photosensitive drum 12. . However, if the amount of bending is too large, a failure such as a paper jam occurs in the paper transport path after the paper leading edge bending means 6.

Hereinafter, the paper tip bending means 6 which is a main part of the present invention will be described with reference to the drawings. In the following drawings, for simplicity, the paper is illustrated as being conveyed from the left side in the drawings, as in FIGS. 1 to 3. Therefore, the bending direction of the leading edge of the paper is downward,
In other words, the paper tip folding means 6 may be mounted such that the paper tip folding means 6 is turned upside down, or the photosensitive drum 12 is turned down, so that the folding direction of the paper tip is in the direction of the photosensitive drum 12. .

FIG. 4 and FIG.
2 shows an embodiment of the means 6 for bending in the direction 2; As shown in FIG. 4, the sheet 4 is conveyed to a guide 32 provided on a stay 30 of the sheet leading edge bending means 6. The fixed blade 34 is attached to the stay 30 or the side plate of the paper tip bending means 6. As shown in FIG. 5, the tip of the fixed blade 34 is rounded unlike the cutter. The folding blade 36 that bends the leading end of the paper 4 is rotatably attached to the side plate. The paper 4 is a fixed blade 34
, And is stopped by the lower blade of the bending blade 36. Thereafter, the folding blade 36 descends, and the leading end of the paper 4 is bent.

FIG. 6 shows a process in which the leading end of the sheet 4 is bent. The sheet 4 is conveyed, the leading end of the sheet 4 collides with the lower blade of the folding blade 36, and the sheet 4 stops. Thereafter, the folding blade 36 descends, and guides the leading end of the paper 4 between the fixed blade 34 and the folding blade 36 to bend by the amount of bending L. The folding blade 36 is rotated in a reciprocating motion type or a rotary motion type.

FIG. 7 shows a control structure for driving the paper tip bending means 6. The paper 4 is stored in the control device 40.
The paper feed roller 44 is driven by the paper feed roller driving means 42 controlled by the controller and is conveyed. The leading edge of the paper 4 is detected by a paper detection sensor 46 disposed immediately before the paper leading edge folding means 6, and the control device 40 determines this detection signal,
A drive signal is output to the folding blade driving means 48 to drive the folding blade 36. After a certain period of time, the control device 40 further drives the folding blade 36 to retreat, and the paper 4
Is transported to the downstream transport path 50. After the sheet 4 has passed the sheet leading edge folding means 6, the folding blade 36 is controlled to stop at the position where the leading edge of the next sheet 4 is stopped by the lower blade again.

As shown in FIG. 8, the amount of bending L by the paper front end bending means 6 is suitably from 0.1 to 0.6 mm. When the bending amount L is 0.1 mm or less, the bending effect is insufficient, and winding around the photosensitive drum 12 occurs. On the other hand, if the bending amount L is larger than 0.6 mm, a failure is likely to occur in the sheet transport path or the stacker.

According to the present embodiment, 0.1 mm to 0.6 mm
The device for bending the paper in the direction of the photoreceptor does not work on thick paper that does not wrap around the photoreceptor. Further, the leading end of the sheet is temporarily stopped by the stopper, and in this state, the leading end of the sheet is 0.1 mm to 0.1 mm.
Since the two-stage blade that bends 6 mm operates so as to act on the leading edge of the sheet, a malfunction such as bending the leading edge of the sheet to a size larger than a specified value is prevented.

FIG. 9 and FIG.
3 shows another embodiment. FIG. 9 is a diagram illustrating a control configuration of the present example, and FIG. 10 is a diagram illustrating a process of operation. As shown in these figures,
In this embodiment, the leading edge of the paper 4 conveyed by the paper feed roller 44 is detected by the paper detection sensor 46, and the reciprocating blade 54 acts from above when the leading edge of the paper 4 protrudes by L from the end surface of the fixed base 52. Then, the portion of L is bent from the end face of the fixing base 52, and thereafter, it is retracted upward again. Also with this embodiment it is possible to obtain the same effect as that of the embodiment of FIG.

In these embodiments, a separating corotron is disposed on the back side of the transfer belt, the paper is pressed against the photoreceptor by a rubber roller having a high electric resistance, or a bias voltage is applied to the rubber roller to suck the toner. Thereby, a clear image without disturbance can be obtained.

[0022]

According to the present invention, it is possible to prevent the sheet from being wound around the photosensitive drum, which is generated by the influence of the curl or the like at the end of the sheet, which occurs when cutting the cut sheet.

Further, since no special means for separating the paper from the photosensitive drum is required, the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an electrophotographic apparatus showing one embodiment of the present invention.

FIG. 2 is a diagram illustrating a phenomenon in which a conventional sheet is wound around a photosensitive drum.

FIG. 3 is a diagram illustrating a phenomenon in which a conventional sheet is wound around a photosensitive drum.

FIG. 4 is a schematic configuration diagram showing a sheet leading end bending means according to an embodiment of the present invention.

FIG. 5 is a schematic enlarged view of a sheet leading end bent portion of FIG. 4;

FIG. 6 is a diagram illustrating a process in which the leading end of a sheet is bent in the embodiment.

FIG. 7 is a control configuration diagram of a sheet leading end bending unit according to the present embodiment.

FIG. 8 is a diagram illustrating a relationship between a bent length L of a leading end of a sheet, a sheet winding around a photosensitive drum, and a sheet conveyance jam.

FIG. 9 is a control configuration diagram of a sheet leading end bending unit according to another embodiment of the present invention.

FIG. 10 is a view showing a process in which the leading end of the sheet in the embodiment of FIG. 9 is bent.

[Explanation of symbols]

 2 Hopper 4 Paper 6 Paper tip bending means 8 Transport roller 10 Transfer belt 12 Photosensitive drum 14 Developing device 16 Transfer corotron 18 Fixing device 20 Unloading roller 22 Optical unit 24 Cleaner 26 Air gap layer 30 Stay 32 Guide guide 34 Fixed blade 36 Bending blade 40 Control device 42 Paper feed roller driving means 44 Paper feed roller 46 Paper detection sensor 48 Bending blade driving means 50 Downstream transport path 52 Fixed table 54 Reciprocating blade

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-212474 (JP, A) JP-A-57-43469 (JP, U) JP-A-57-63352 (JP, U) Field (Int.Cl. ⁷ , DB name) G03G 15/00 510 B65H 5/00 B65H 29/54 B65H 29/70

Claims (12)

(57) [Claims] A sheet feeder for separating and feeding the stacked sheets one by one; an endless transfer belt made of a dielectric material for electrostatically attracting and conveying the sheets; a pulley for driving the transfer belt; And at least one or more pulleys for stretching the transfer belt, an electrostatic latent image corresponding to the printing information, a photoconductor holding a toner electrostatically adsorbed on the electrostatic latent image, and a toner image on the photoconductor An electrophotographic apparatus comprising a transfer unit which is in contact with the photoconductor and the transfer belt in a state of being in contact with the photoconductor, in order to transfer the paper to the paper being conveyed by the transfer belt. between the transfer section, the direction of the tip <br/> the photosensitive body of the paper, and the paper surface of the photosensitive member and the opposite side
Is an electrophotographic apparatus provided with a means for folding the sheet into a planar shape . A sheet feeder for separating and feeding the stacked sheets one by one; an endless transfer belt made of a dielectric material for electrostatically adsorbing and conveying the sheets; a pulley for driving the transfer belt; And at least one or more pulleys for stretching the transfer belt, an electrostatic latent image corresponding to the printing information, a photoconductor holding a toner electrostatically adsorbed on the electrostatic latent image, and a toner image on the photoconductor An electrophotographic apparatus comprising a transfer unit which is in contact with the photoconductor and the transfer belt in a state of being in contact with the photoconductor, in order to transfer the paper to the paper being conveyed by the transfer belt. A supporting portion for supporting the leading end of the sheet, a fixed portion having a rounded corner in contact with the leading end of the sheet, and a predetermined gap from the fixed portion; The paper tip in the gap with the fixing portion. An electrophotographic apparatus , comprising: a moving portion for bending an end in the direction of the photoreceptor; 3. The electrophotographic apparatus according to claim 2, wherein
The electrophotographic apparatus according to claim 1, wherein the moving section has a contact section for contacting and stopping a leading end of the conveyed sheet. 4. The electrophotographic apparatus according to claim 2, wherein
The electrophotographic apparatus, wherein the moving unit is configured to rotate. 5. The electrophotographic apparatus according to claim 2, wherein
The electrophotographic apparatus, wherein the moving unit is configured to reciprocate in a linear direction. 6. The electrophotographic apparatus according to claim 2, wherein
The electrophotographic apparatus according to claim 1, wherein a gap between the fixed portion and the moving portion is such that a bent length of a leading end portion of the sheet is 0.1 mm to 0.6 mm. 7. The electrophotographic apparatus according to claim 1, further comprising a transfer corotron on the back side of the transfer belt. 8. The electrophotographic apparatus according to claim 1, further comprising a transfer corotron and a separation corotron on a back side of the transfer belt. 9. The electrophotographic apparatus according to claim 1, wherein the paper is pressed against the photoconductor.
An electrophotographic apparatus comprising: a rubber roller having a high electric resistance for transferring a toner image on the photosensitive member onto the sheet; 10. The electrophotographic apparatus according to claim 1, wherein a bias voltage for transferring the toner image on the photoconductor to the paper by pressing the paper against the photoconductor against the transfer unit is provided. An electrophotographic apparatus comprising a rubber roller having a high applied electric resistance. 11. A method for separating and feeding the stacked sheets one by one, conveying the sheets by electrostatic attraction using an endless transfer belt made of a dielectric, and forming an electrostatic latent image corresponding to print information and the electrostatic latent image. A toner image on the photoconductor is conveyed by the transfer belt at a transfer section in which the transfer sheet is in contact with a photoconductor holding toner electrostatically adsorbed on the electrostatic latent image with the transfer belt therebetween. In a method of preventing winding of a sheet around the photoreceptor of an electrophotographic apparatus that transfers the sheet to a sheet, a front end of the sheet to be conveyed to the transfer unit is bent in the direction of the photoreceptor, and the photoreceptor and The other side of the paper
A method for preventing paper from wrapping around a photoreceptor of an electrophotographic apparatus, wherein the method has a planar shape . 12. The method according to claim 11, wherein the bent length of the leading end of the paper is 0.1 mm to 0.6 m.
m, wherein the paper is prevented from wrapping around the photosensitive member of the electrophotographic apparatus.