JPH05134563A - Form guiding device - Google Patents

Abstract

PURPOSE:To realize the prevention of deterioration in a transfer for a toner image while preventing the occurrence of paper jamming by providing pads for highly absorbing oscillation on form path sides of two guiding plates arranged between a resist roller sending a form to a transfer unit and it. CONSTITUTION:The guiding plates 20a and 20b are arranged so that gaps opposed each other, taper, narrow parallel gap paths for the form are formed inside the pads for highly absorbing the oscillation 20c and 20d, and provided in shorter ranges than the top ends of the guiding plates 20a and 20b, and flexible films 20e and 20f whose tailing edges are longer than the top ends of the pads for highly absorbing the oscillation 20c and 20d, and which has high lubricity, are arranged on the surfaces of the pads 20c and 20d. The tailing edge part of the film 20f guiding the rear side of the form, is brought into contact with the top end part of the guiding plate 20b, to regulate a guiding surface, and the leading edge part of the film 20e guiding the front side, has a gap delta against the top end part of the guiding plate 20a, to provide a relief place. Then, a deformed form is straightened, and sent to the transfer unit, to prevent the skipping of the transfer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper guide device in an electrophotographic apparatus such as an electrophotographic copying machine or an electrophotographic printer, and more particularly, a paper for transferring a toner image formed on the surface of a rotary drum is transferred from a conveying roller. The present invention relates to a paper guide device that guides a container.

[0002]

2. Description of the Related Art In an electrophotographic apparatus such as an electrophotographic copying machine or an electrophotographic printer, a toner image formed on a surface of a rotary drum such as a photosensitive drum or an intermediate transfer drum is transferred onto a sheet and then fixed on the sheet for copying. Eject as printed matter or printed matter.
A transfer device for transferring the toner image on the surface of the rotary drum to the paper is provided so as to face the rotary drum, and the paper fed from the transport roller and guided by the paper guide device is brought into contact with the surface of the rotary drum. In this state, a transfer charge is applied to the back surface of the sheet to electrostatically transfer the toner image. Various measures have been taken in order to efficiently transfer the toner image from the rotating drum onto the paper to improve the image quality. For example, in order to increase the contact pressure of the paper against the surface of the rotating drum, the paper is bent once to increase the rigidity of the paper, or two corona discharge wires of the transfer device are used to increase the transfer charge amount. A method of increasing the charging power by hanging it has been tried.

However, these methods are not effective in an electrophotographic apparatus which has a curved paper conveyance path, uses many kinds of paper, or performs double-sided printing, and deteriorates the image quality in some cases. Acts like. For example, in an automatic photographic device that continuously feeds paper from a paper feed cassette and in an electrophotographic apparatus that manually feeds paper in a direction opposite to the automatic feed, the paper is fed from different directions. The paper guide device is arranged so as to guide the paper linearly on the tangent line of the rotary drum and feed it to the transfer device. For this reason, it is difficult for the method of increasing the rigidity of the paper in order to improve the transfer efficiency so as to obtain the same effects as those of both the automatic paper feeding and the manual paper feeding. Moreover, since the sheet conveying path leading to the conveying roller is curved, the sheet passes through the conveying roller in an elastically deformed state, and the trailing edge of the sheet leaves the conveying roller and leaves its own position in the sheet guide device. It vibrates when trying to return to the original flat state due to elasticity, and this vibration is transmitted to the transfer portion and causes transfer deviation. Further, since backside printing in an electrophotographic apparatus that performs double-sided printing is performed after a step of fixing the toner image transferred on the front side, the sheet is deformed by heating in the fixing step, and the deformed portion is a conveyance roller. Similar vibrations are generated when passing through, and the deformed portion is less likely to come into close contact with the rotating drum, which also causes transfer omission. In particular,
In the case of thick paper having a thickness of 120 to 130 μm or more, postcards, etc., these tendencies are remarkable in both single-sided printing and double-sided printing.

FIG. 5 to FIG. 7 concretely show the sheet conveyance for the toner image transfer, the transfer deviation and the paper jam occurrence in such a conventional electrophotographic apparatus.

FIGS. 5 and 6 are for explaining transfer deviation and transfer omission due to vibration and deformation (curl) of the sheet, and the rotary drum 1 transfers the toner images of respective colors formed on a photoreceptor (not shown) in an overlapping manner. The color toner image 2a thus formed is carried and rotated in the arrow direction. The transfer device 3 is provided with a corona discharge wire 3a for transferring a toner image, an AC corona discharge wire 3b for discharging a transfer charge, and a paper guide 3c, and while the paper 4 that has been sent comes into contact with the rotary drum 1 and moves. The toner image transfer charges emitted from the corona discharge wire 3a are applied to the back surface of the sheet 4 to electrostatically transfer the toner image 2a on the rotating drum 1 to the surface of the sheet 4 at the transfer point T, and the transferred toner. The charge for transfer charge elimination emitted from the corona discharge wire 3b is applied to the back surface of the sheet 4 that carries the image 2b to neutralize the transfer charge on the back surface, and the sheet 4 is moved to the rotary drum 1 Separate from.

The sheet conveying means for feeding the sheet 4 to the transfer device 3 arranges the posture of the sheet 4 and adjusts the conveying timing so that the toner image 2a formed on the rotary drum 1 and the sheet 4 are aligned at the transfer point T. The registration rollers 5a and 5b, and the guide plates 6a that guide the sheet 4 sent from the registration rollers 5a and 5b to the transfer device 3.
6b is provided. The opposing gap between the guide plates 6a and 6b is
A sheet path is wide on the side of the registration rollers 5a and 5b (rear end side) and narrow on the side of the transfer device 3 (front end side).

The transfer device 3 is constituted by such a sheet conveying means.
When the rear end portion of the sheet 4 fed into the sheet is deformed, the sheet 4 passes through the registration rollers 5a and 5b while being straightened (elastically deformed) by the registration rollers 5a and 5b, so that the rear edge is When returning to the original deformed state after leaving the registration rollers 5a and 5b, for example, as shown in the drawing, the rear end portion bounces toward the guide plate 6a and collides with the guide plate 6a to vibrate. Therefore, at this time, the transfer of the toner image 2a onto the paper portion (area L) after the transfer point T causes a transfer deviation due to the influence of the vibration. In particular, this vibration occurs with the transfer point T as a fulcrum, so that the paper 4 near the transfer point repeats contact and separation with the rotating drum 4 to generate streak-like transfer unevenness as shown in FIG. ..

[0008] These problems are caused by suppressing the vibration of the sheet 4 by narrowing the gap (sheet passage) between the guide plates 6a and 6b,
Although it can be alleviated by correcting the deformation, if the paper passage is narrowed, a paper passing resistance increases and a new problem that paper jam easily occurs occurs. FIG. 7 shows the guide plates 6a, 6
It shows a state in which a paper jam has occurred due to an increase in the sheet passing resistance due to the deformation of the leading end portion of the sheet 4 when the gap between b is narrowed. Further, even if the paper jam does not occur, if the sheet passing resistance is not uniform in the paper width direction, the advance of the leading edge of the paper 4 is slowed and the paper 4 is tilted, so that the toner image cannot be accurately transferred. There is.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a paper guide device which can prevent deterioration of a toner image transfer due to vibration and deformation of paper while preventing paper jam.

[0010]

According to the present invention, a transfer roller for transferring a toner image on a rotary drum to a sheet is arranged between the transfer roller and the transfer roller for feeding the sheet to the transfer roller, and is sent out from the transfer roller. In a paper guide device provided with a pair of guide plates facing each other across a paper path so as to guide the paper to the transfer device, an elastic body is arranged on the paper path side of the guide plate.

[0011]

Function: Deformation (curl) by narrowing the paper passage formed between the elastic bodies provided inside the pair of guide plates
It is possible to straighten the formed paper and send it to the transfer device to prevent transfer omission, and suppress the occurrence of vibration even when the trailing edge of the paper separates from the transport roller or attenuate the generated vibration. The transfer of the vibration to the transfer point is suppressed to prevent transfer deviation, and when the paper strongly contacts the elastic body, the elastic body is elastically deformed and the paper passing resistance is prevented from becoming excessively large. Prevent the occurrence of jams.

[0012]

Embodiments of the present invention will be described with reference to the drawings.
FIG. 2 is a vertical side view of the color electrophotographic printer. 7
Is a photoconductor belt stretched to rotate in the direction of the arrow,
A charger 8 and a laser exposure device 9 are provided around the photosensitive belt 7.
The developing devices 10a to 10d, the transfer drum 11, and the cleaner 12 are arranged. The rotating photoreceptor belt 7 is uniformly charged by the charger 8 and exposed by the laser exposure device 9 to form an electrostatic latent image. The toner of the color corresponding to the electrostatic latent image is used as the developer. The toner image is developed by the developing devices 10a to 10d, and is transferred to the transfer drum 11. After the transfer of the toner image, the photoconductor belt 7 is cleaned by the cleaner 12, and similarly, a toner image of a different color is formed again, and the toner image is transferred onto the transfer drum 11 so that a color toner image is formed on the transfer drum 11. To do.

In order to feed the paper 13 on which the color toner image formed on the transfer drum 11 is transferred, an automatic paper feed mechanism having an automatic paper feed cassette 14 and an extraction roller 15, a manual feed cassette 16 and an extraction roller 17 are provided. There is provided a manual paper feeding mechanism including. The paper feed guide 18 registers the paper 13 sent from both paper feed mechanisms with registration rollers 19a and 19b.
It is provided to guide you. Registration roller 19
The sheets a and 19b receive the leading edge of the sheet 13 sent from the sheet feeding mechanism, arrange the sheet, and adjust the transport timing so as to match the toner image on the transfer drum 11, and send out the sheet 13.

The paper guide device 20 according to the present invention guides the paper 13 sent from the registration rollers 19a and 19b to the transfer device 21, and as shown in FIG.
Two guide plates 20 facing each other so as to be separable in a divided structure
High vibration absorbing pads 20c, 20d formed of sponge such as polyurethane or rubber and rich in elasticity are attached to the inside of a, 20b, and flexible and highly slippery on the inner surface of the high vibration absorbing pads 20c, 20d. Film (polyethylene terephthalate film, polytetrafluoroethylene film, etc.) 2
This is a configuration in which 0e and 20f are joined to form a paper passage having a narrow gap.

The two guide plates 20a, 20b are arranged so that the facing gap is narrowed, and the high vibration absorbing pads 20c, 2 are provided.
0d is provided in a range shorter than the tips of the two guide plates 20a and 20b so that a sheet passage with a narrow parallel gap is formed inside thereof, and the high vibration absorbing pads 20c and 20d are provided on the surface thereof.
Highly slippery flexible film 20e longer than the tip of the
20f is arranged. The leading end portion of the film 20f that guides the back side of the paper 13 contacts the leading end portion of the guide plate 20b to regulate the guide surface, and the film 2 that guides the front side.
The leading end portion of 0e is δ between the leading end portion of the guide plate 20a.
An escape area is provided by forming a gap.

When the paper 13 fed by the paper guide device 20 moves while contacting the transfer drum 11, the transfer device 21 gives a transfer charge to the back surface of the paper 13 to form a toner image on the transfer drum 11. The sheet 13 is transferred onto the surface of the sheet 13, and then the transfer charge is neutralized to separate the sheet 13 from the surface of the transfer drum 11. The peeling claw 22 assists the sheet separation from the transfer drum 11.

The fixing device 23 is a sheet 1 on which the toner image is transferred.
3 to heat and fix the toner image on the sheet 13,
The paper discharge roller 24 discharges the paper 13 on which the toner image is fixed onto the paper discharge tray 25.

FIG. 3 shows a state in which the sheet 13 whose rear end portion is deformed toward the guide plate 20a moves in the sheet guide device 20 in such a color electrophotographic printer. The trailing edges of the paper 13 are registration rollers 19a and 19b.
After leaving, the rear end portion elastically bounces toward the guide plate 20a and collides with the high vibration absorption pad 20c (highly slippery film 20e) inside the guide plate 20a. This collision energy is absorbed by the high vibration absorption pad 20c, or the generated vibration is absorbed and attenuated. Therefore, the vibration of the paper 13 is not transmitted to the transfer point and the transfer deviation does not occur. Even when the paper 13 is deformed to the opposite side, the transfer deviation does not occur due to the same action. Moreover, since the paper passage is formed with a narrow parallel gap, the paper 13 can be guided to the transfer device 21 while correcting the deformation, and the transfer omission can be prevented.

FIG. 4 shows a state in which a highly rigid sheet 13 such as a thick sheet having a thickness of 150 μm or more, the tip portion of which is deformed toward the guide plate 20a, moves in the narrow sheet passage of the sheet guide device 20. .. When the high-rigidity sheet 13 is deformed, the highly slippery film 20e compresses the high vibration-absorbing pad 20c or bends to escape the gap δ until it comes into contact with the guide plate 20a. Thirteen
The increase in the paper passing resistance due to the rubbing against the paper is reduced, and the occurrence of the paper jam due to the excessive paper passing resistance is prevented. Also, paper 1
When 3 is deformed to the opposite side, the highly slippery film 20
Since the tip portion of f is pressed by the guide plate 20b,
The high vibration absorption pad 20c side is bent to suppress an increase in paper passing resistance.

Therefore, according to such a paper guide device 20, the paper 1 whose front end portion and rear end portion are deformed (curled)
3 can be guided to the transfer point while being corrected in a narrow paper path, so that the transfer failure of the front end portion and the rear end portion of the paper and the transfer deviation of the rear end portion of the paper can be prevented, and a good toner image can be transferred. It will be possible. Moreover, with respect to the deformation of the highly rigid sheet 13, the highly slippery films 20e and 20f bend the high vibration absorbing pads 20c and 20d or escape so as to narrow the gap δ, resulting in excessive sheet passing resistance. To prevent paper jams.

[0021]

According to the present invention, by narrowing the paper passage formed between the elastic bodies provided inside the two guide plates, the deformed (curled) paper is corrected to be flat and the transfer device. It is possible to prevent transfer omission by feeding the paper to the transfer roller, and suppress the occurrence of vibration even when the rear end of the sheet separates from the conveyance roller or attenuate the generated vibration and transmit the vibration to the transfer point. To prevent the transfer deviation, and to prevent the paper jam from occurring by suppressing the elastic resistance of the paper elastically deforming when the paper comes into strong contact with the paper elastic body.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a paper guide device according to the present invention.

FIG. 2 is a vertical sectional side view of a color electrophotographic printer according to the present invention.

FIG. 3 is a vertical cross-sectional side view showing a state in which a sheet having a deformed rear end portion moves inside the sheet guide device according to the present invention.

FIG. 4 is a vertical cross-sectional side view showing a state in which a high-rigidity paper sheet having a deformed front end portion moves inside the paper guide apparatus according to the present invention.

FIG. 5 is a vertical cross-sectional side view of a sheet conveying mechanism and a transfer device for transferring a toner image in a conventional electrophotographic apparatus.

FIG. 6 is a plan view of a sheet on which a toner image is transferred by a conventional electrophotographic apparatus.

FIG. 7 is a vertical cross-sectional side view showing a state where a paper jam has occurred in a narrow paper passage of a paper guide device in a conventional electrophotographic apparatus.

[Explanation of symbols]

 11 Transfer Drum 13 Paper 19a, 19b Registration Roller 20 Paper Guide Device 20a, 20b Guide Plate 20c, 20d High Vibration Absorbing Pad 20e, 20f High Sliding Film 21 Transfer Device

Claims (6)

[Claims] 1. A transfer roller for transferring a toner image on a rotating drum to a sheet, the transfer roller being disposed between the transfer roller and the transfer roller, and guiding the sheet sent out from the transfer roller to the transfer roller. A paper guide device comprising a pair of guide plates facing each other across a paper passage, wherein an elastic body is arranged on the paper passage side of the guide plate. 2. The paper guide device according to claim 1, wherein the elastic body is provided inside both guide plates, and a paper guide surface thereof is a highly sliding surface. 3. The apparatus according to claim 1, wherein the guide plates are arranged such that a facing gap between them is narrowed, and the elastic body is arranged such that a paper passage formed inside thereof is a parallel gap. Characteristic paper guide device. 4. The sheet guide device according to claim 1, wherein the pair of guide plates face each other in a separable manner. 5. The elastic body according to claim 1, wherein the elastic body is provided inside each of the guide plates in a range shorter than a tip of each of the guide plates.
A sheet guide device, characterized in that a flexible plate having a high sliding surface is arranged on the surface in a range longer than the tip of the elastic body. 6. The sheet guide device according to claim 1, wherein the elastic body includes a high vibration absorbing member.