JP2000066524A - Paper separating device for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make excellently separable recording paper even in the case of using a high-viscosity liquid toner exerting influence on adhesion between the recording paper and the toner. SOLUTION: This paper separating device is equipped with a rotatable transfer roller 8 which is arranged to be opposed to an image carrier and to which bias voltage for transfer is applied, an endless belt means 15 laid over pulleys 12 and 14 arranged at a position corresponding to a margin part on the recording paper at least on either side in the axial direction of the roller 8 and provided at an opposed position where the roller 8 and the image carrier 6 are opposed in the moving direction of the recording paper and on a side where the recording paper is ejected from the opposed position, and a separator means 16 abutting on the outer surface of the belt means 15; and the end in the width direction of the recording paper fed to the opposed position where the image carrier 6 and the roller 8 are opposed is held and fed in a state where it is peeled from the surface of the image carrier 6 by the belt means 15 and the separator means 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet separating device for an image forming apparatus, and more particularly, to a method in which an image on a latent image carrier is temporarily transferred to an intermediate transfer member once, and the intermediate transfer member transfers the image to a sheet such as recording paper. The present invention relates to a mechanism for separating a sheet from an intermediate transfer member after secondary transfer to a sheet.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic copying machine, a facsimile machine, and a printer, when a photosensitive drum, which is a drum-shaped latent image carrier, is used, a photosensitive member uniformly charged is used. A writing process is performed on the drum using laser light or the like to form an electrostatic latent image,
The electrostatic latent image is processed into a visible image by a developing process using toner. The visible image is electrostatically transferred to a recording sheet and then fixed by a fixing device to obtain a copy image.

As a method of transferring an image to a recording sheet, instead of the method of directly transferring the image from the photosensitive drum to the recording sheet, the image is temporarily transferred from the photosensitive drum to an intermediate transfer body using a belt or the like, and then the intermediate transfer is performed. There is a method of secondary transfer from a body to recording paper. This transfer method is used when images of a plurality of colors are sequentially transferred to an intermediate transfer body, and a finally superimposed image, for example, a full-color image, is collectively transferred to recording paper.

[0004] As an example, there is the following configuration when an intermediate transfer member is used. A belt is used as the intermediate transfer member, and the belt is wrapped around a plurality of pulleys, and a part of the extended portion is opposed to and abuts on the photosensitive drum so that primary transfer can be performed. The image primarily transferred to the belt-shaped intermediate transfer body is secondarily transferred by contacting the recording paper,
Thereafter, the recording paper is separated from the intermediate transfer member.

As a structure for separating the recording paper from the photosensitive drum or the intermediate transfer member, there are a curvature separation system and a system using a pick-off blade. The former method is provided with a roller having a small radius of curvature, for example, capable of rapidly changing the sheet conveyance direction on the sheet discharge side in the recording sheet conveyance path, and the strength of the recording sheet stiffness, so-called,
Using the bending stiffness, the recording paper is separated by not following a sudden change in the transport path.
A pick-off blade is arranged at a position corresponding to the marginal position (one side) of the paper end on the surface of the photoreceptor or the intermediate transfer member, and the portion is peeled off by utilizing the fact that the margin does not adhere to the photoreceptor or the intermediate transfer member. It is a system that separates them.

[0006]

In each of the above methods, there are the following problems, and complete separation cannot be performed in some cases. Each of the above methods is a low-cost mechanism because there is no need to provide a separation mechanism that performs a special operation.However, when thin paper with low stiffness, coated paper with good smoothness, or high-viscosity liquid toner is used, In some cases, the separation property may be deteriorated due to the influence of the adhesive force of the toner or the adhesion between the paper and the photoconductor or the intermediate transfer body. For this reason,
There is a possibility that the recording sheet is wound and not separated, or the recording sheet is detached from the pick-off blade to cause paper jam or wrinkles.

SUMMARY OF THE INVENTION In view of the above-mentioned problems in the conventional separation apparatus, the object of the present invention is to reliably perform separation on a wide variety of recording papers such as thin paper to thick paper or coated paper, and to ensure adhesion between the paper and recording paper. It is an object of the present invention to provide a sheet separating device of an image forming apparatus having a configuration capable of separating well even when using a high-viscosity liquid toner that affects the toner.

[0008]

According to the first aspect of the present invention,
In an image forming apparatus having a configuration for transferring the visible image to a recording sheet moving at a constant speed with an image carrier carrying a visible image, the image forming apparatus is disposed to face the image carrier, and a transfer bias voltage is set. A rotatable transfer roller to be applied, and the transfer roller and the image carrier are disposed at a position corresponding to a margin on the recording sheet on at least one side in the axial direction of the transfer roller, and in a moving direction of the recording sheet. Endless belt means wound around pulleys provided at the opposite position and the side from which the recording paper is discharged from the opposite position, and disposed near the opposite position of the image carrier to the transfer roller. And a separator in contact with the outer surface of the endless belt means, and a widthwise end of the recording sheet fed toward a position facing the image carrier and the transfer roller. The are characterized and characterized in that the pinched and conveyed in a state of being detached from the surface of the image bearing member and said endless belt means and said separator means.

According to a second aspect of the present invention, in the sheet separating apparatus of the image forming apparatus according to the first aspect, the separator is urged toward the outer surface of the endless belt. .

According to a third aspect of the present invention, in the sheet separating device of the image forming apparatus according to the first aspect, the endless belt is driven to rotate substantially at the same speed as the surface speed of the transfer roller. .

[0011]

FIG. 1 is a schematic diagram for explaining the configuration of an image forming apparatus to which a sheet separating apparatus according to an embodiment of the present invention is applied. In FIG. After the images are sequentially transferred to the intermediate transfer member, the image superimposed on the intermediate transfer member is collectively transferred to recording paper. Hereinafter, the configuration will be described.

The image forming apparatus is a photosensitive drum 1 having a drum shape.
Around the photosensitive drum 1, a wet developing device 4 having a roller-shaped charging device 2, a laser optical device 3, and a developing roller 4A along a rotation direction (the direction of the arrow in the drawing)
The cleaning device 5 is disposed upstream of the charging device 2 in the rotation direction of the photosensitive drum 1.

After the photosensitive drum 1 is uniformly charged by the charging device 2, the laser optical device 3 performs writing with laser light based on a signal from an image processing device (not shown) to form an electrostatic latent image. After the electrostatic latent image carried on the surface is subjected to visible image processing by the developing device 4, the visible image is primarily transferred to an intermediate transfer member described later. After the primary transfer, the photosensitive drum 1 is cleaned of excess toner by the cleaning device 5 and uniformly charged by the charging device 2 to prepare for the subsequent image processing.

The intermediate transfer member includes a plurality of pulleys 6A, 6B, 6
The transfer belt 6 is wound around C and 6D, and among the pulleys, the pulley indicated by reference numeral 6A is rotated by a driving source (not shown) so that the pulley 6A is at the position facing the photosensitive drum 1. It moves in the direction. A primary transfer roller 7 that applies a transfer bias voltage across the transfer belt 6 is opposed to and abuts on a position (position indicated by a reference sign P1 in FIG. 1) of the extended portion of the transfer belt 6 that faces the photosensitive drum 1. Let me do it. A position facing the drive pulley 6A with the transfer belt 6 interposed therebetween (in FIG.
2), a secondary transfer roller 8 that can be moved toward and away from the transfer belt 6 is disposed. Paper feed roller pair 9 for recording paper S fed from the apparatus
And a guide member 10 are arranged side by side from the upstream side to the downstream side in the paper feeding direction indicated by the arrow. Drive pulley 6
A cleaning blade 11 for an intermediate transfer belt that is in contact with the transfer belt 6 is brought into contact with the vicinity of a position where the transfer roller A and the secondary transfer roller 8 are opposed to each other, and removes toner remaining on the transfer belt 6 after the secondary transfer. It is supposed to.

The intermediate transfer member has a function of transferring the visible image carried on the photosensitive drum 1 to the recording paper S by a secondary transfer process. When the visible image of each color is primary-transferred from the photosensitive drum 1 and superimposed, it is collectively transferred to the recording paper S by secondary transfer. When performing secondary transfer for multicolor images,
Secondary transfer roller 8 until the primary transfer of the final color image is completed.
Is held at a position separated from the transfer belt 6 (a position indicated by a two-dot line in FIG. 1).

The secondary transfer roller 8 is provided with a separation mechanism for the recording paper S after the secondary transfer. 2 and 3 are views showing the relationship between the secondary transfer roller 8, the transfer belt 6, and the driving pulley 6A, and showing the drive structure of the secondary transfer roller 8, respectively. The main pulley 12 is supported coaxially.
The secondary transfer roller 8 is formed by covering a metal core with a medium-resistance conductive rubber made of hydrin rubber, and as shown in FIG.
Are integrated and attached. In the secondary transfer, a transfer bias voltage is applied between the core metal of the secondary transfer roller 8 and the driving pulley 6A of the transfer belt 6, and the developed toner image is electrostatically transferred to the recording paper S abutting on the transfer belt 6. .

As shown in FIG. 3, the main pulley 12 is disposed in a margin of the recording sheet S corresponding to a position where the axial end of the secondary transfer roller 8 does not face in the axial direction of the photosensitive drum 1. And a gear 12 </ b> A integrated with the rotation shaft of the secondary transfer roller 8.

The secondary transfer roller 8 and the main pulley 12
As shown in FIG. 3, the rotational force from a drive source (not shown) is reduced by a compound gear 13 which is a driving unit having teeth that can mesh with the gear 8 </ b> B of the secondary transfer roller 8 and the gear 12 </ b> A of the main pulley 12. It is transmitted and can be rotated with a substantially matched surface speed.

The main pulley 12 has a sub pulley 14 described later.
And one end in the extending direction of the separation belt 15 wrapped around the end. The auxiliary pulley 14 has a smaller diameter than the main pulley 12, and is disposed on a side where the recording sheet S is discharged from a position where the secondary transfer roller 8 and the driving pulley 6 </ b> A of the transfer belt 6 are opposed to each other, and an image forming apparatus (not shown) It is rotatably supported by the side plate of the main body. The separation belt 15 wrapped around the main pulley 12 and the sub pulley 14 is made of elastic rubber such as urethane rubber, and a part of the extended portion (a portion indicated by reference numeral 15A in FIG. 2) is a driving pulley 6A. And is separated from the surface of the transfer belt 6 by about 0.5 to 2.0 mm at a position facing the drive pulley 6A.

In FIG. 2, a separator 16 is disposed on the outer surface of the extending portion 15A of the separation belt 15 parallel to the tangential direction of the driving pulley 6A. The separator 16 is made of a stainless steel thin plate or a plastic sheet piece having a width corresponding to the margin of the recording paper S, and has a smooth surface facing the separation belt 15. Both ends in the extending direction are supported by insulating fixing stands 17 and 18 which are respectively disposed at positions facing each other with the position facing the secondary transfer roller 8. In this embodiment, the lower surface of the separator 16 is 0.5 to 2.
0 mm is separated from the transfer belt 6.
The above toner is prevented from adhering. A pressing member 19 made of an elastic member supported by an insulating fixing base 17 is in contact with a part of the separator 16 that is in contact with a part 15A of the extended portion of the separation belt 15 and is in contact with the separator 16.
The separator 16 is urged toward the separation belt 15. A film such as Teflon may be formed on the surface of the separator 16 in order to realize low friction. In FIG. 2, reference numeral 10 denotes a guide member for the recording paper S shown in FIG.

Since the present embodiment has the above configuration,
The recording sheet S is fed from the sheet feeding device when the primary transfer process is completed, and is sent to a position where the secondary transfer roller 8 which is a secondary transfer position and the driving pulley 6A of the transfer belt 6 are opposed to each other. In FIG. 2, when the leading end of the recording paper S approaches the position facing the secondary transfer roller 8 and the transfer belt 6, one margin in the width direction, which is a direction perpendicular to the traveling direction, is separated by the separation belt 15 and the separator 16. And sandwiched between
In this state, the sheet is conveyed in conjunction with the movement of the separation belt 15. As a result, even when the transfer belt 6 is to be rolled along the peripheral surface of the driving pulley 6A while an area other than the one side in the width direction of the recording sheet S is stuck to the transfer belt 6, the one side in the width direction of the recording sheet S is , The recording paper S is peeled from one side in the width direction to the other area. The range in which the recording paper S is sandwiched between the separation belt 15 and the separator 16 is as follows.
This is the range indicated by the symbol L in FIG.

According to the present embodiment, the recording paper is nipped and conveyed in a direction different from the moving direction when the recording paper is moved while the other part is stuck to the transfer belt 6.
The transfer belt 6 is continuously provided except for a margin portion not nipped and conveyed.
And the moving direction can be changed in the same direction as the nipping and conveying direction.

In this embodiment, the case where the separation belt 15 and the separator 16 are provided at one end in the axial direction of the secondary transfer roller 8 has been described. However, the present invention is not limited to this example and both ends in the axial direction are provided. Can also be provided. In addition to the above configuration, it is also possible to perform curvature separation using the curvature of the transfer belt 6, and in this case, the radius of the drive pulley 6A of the transfer belt 6 may be reduced.

[0024]

According to the first aspect of the present invention, the recording sheet is nipped and conveyed by the endless belt and the separator in a state where the widthwise end of the recording sheet is separated from the surface of the image carrier. Even if a portion other than the end in the direction is stuck to the image carrier and tries to follow it, the recording paper is peeled off from the end in the width direction to the other portion to be separated.
Thus, the recording paper can be reliably separated regardless of the stiffness affected by the thickness of the recording paper or the viscosity of the developer used for visible image processing.

According to the second aspect of the present invention, the separator is pressed and urged toward the separation belt means.
The recording paper can be reliably pinched, whereby the separation and separation of the recording paper from the surface of the image carrier can be reliably performed.

According to the third aspect of the present invention, since the driving means for making the surface speed of the endless belt means substantially equal to the surface speed of the transfer roller is provided, adverse effects such as wrinkling and waving of the recording paper due to the speed deviation are provided. It can be eliminated.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining a main configuration of an image forming apparatus to which a sheet separating apparatus according to an embodiment of the present invention is applied.

FIG. 2 is a schematic diagram for explaining a main configuration of a sheet separating apparatus according to an embodiment of the present invention.

FIG. 3 is a partial cross-sectional view illustrating a configuration of a driving unit in the sheet separating apparatus shown in FIG.

[Explanation of symbols]

 Reference Signs List 1 photoreceptor drum 8 secondary transfer roller 8A rotating shaft 8B gear 12 main pulley 12A gear 13 composite gear serving as driving means 14 auxiliary pulley 15 separation belt 16 separator S recording paper

Claims (3)

[Claims] An image forming apparatus configured to transfer the visible image onto a recording sheet moving at a constant speed with an image carrier carrying a visible image, wherein the image forming apparatus is disposed to face the image carrier; A rotatable transfer roller for applying a transfer bias voltage, disposed at a position corresponding to a margin on the recording sheet on at least one side in the axial direction of the transfer roller, and the transfer roller in a moving direction of the recording sheet. An endless belt means wound around pulleys provided at a position facing the image carrier and a side from which the recording sheet is discharged from the facing position; and a transfer roller provided at the image carrier. A separator disposed in the vicinity of the facing position and in contact with the outer surface of the endless belt means, wherein the recording is fed toward the facing position of the image carrier and the transfer roller. A sheet separating apparatus for an image forming apparatus, wherein a widthwise end of a sheet is pinched and conveyed while being separated from the surface of the image carrier by the endless belt means and the separator means. 2. A sheet separating apparatus according to claim 1, wherein said separator is urged toward an outer surface of said endless belt. apparatus. 3. A sheet separating apparatus according to claim 1, wherein said endless belt is driven to rotate substantially in accordance with a surface speed of said transfer roller. apparatus.