JPH03236080A - Transfer roller device - Google Patents

Abstract

PURPOSE:To decrease transfer defect by providing outer peripheral surface members consisting of elastic bodies divided to plural cylindrical members on a back up roller and setting the pressure for pressurized contact with paper at the increasingly lower pressure the nearer the central side where the number of the divided surface is large. CONSTITUTION:The elastic deformation larger toward the central side is generated in the outer peripheral member 36. This member 36 is divided to the cylindrical members 36a and the number of the divisions per unit length is set larger in the central side than on both end sides in the axial direction. Discontinuous differences arise in the elastic deformation rates on both sides of the tight contact end faces between the adjacent members 36a. Elastic reactions are discontinuous as well and friction forces are generated on these tight contact end faces and act as the forces to counter the elastic reactions. The forces lower than the forces corresponding to the elastic deformation rates of the members 36 are pressed by these members and act as the reactions on the transfer roller. The paper is thus transported between the transfer roller and the back up roller 13C in the state in which the pressure contact with the paper is larger the nearer both sides. The generation of the transfer defect is obviated in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transfer roller device applied to electrophotographic copying machines, printers, and the like.

[Conventional technology]

For example, in a full-color copying machine, normally yellow, magenta, and cyan toner images are formed individually on a photoreceptor belt, and then they are sequentially transferred onto an intermediate transfer belt in an overlapping state. Next, the toner images superimposed on this intermediate transfer belt are transferred onto paper.

The transfer from the intermediate transfer belt to the paper is performed by supporting the intermediate transfer belt 42 from the back side with a rubber backup roller 41 and feeding the transfer belt 43 so as to overlap the intermediate transfer belt 42, as shown in FIG. At the same time, a metallic transfer roller 44 is pressed against the intermediate transfer belt 42 via the paper 43 at a position corresponding to the backup roller 41, and in this state, a transfer voltage is applied between the transfer roller 44 and the backup roller 41 side. This is done by applying a voltage. The transfer roller 44 as described above is manufactured with a processing accuracy of, for example, a cylindricity of about 0.01 mm or less in order to make the pressure distribution as uniform as possible during the transfer.

[Problem to be solved by the invention]

However, conventionally, even if the transfer roller 44 has the above-mentioned allowable cylindricity, if the outer diameter is larger at the center than at both ends, as shown in FIG. 7, for example, the cylindricity Δ
A shape in which D is close to the above allowable limit of 0.01 mm (hereinafter referred to as 0.01 mm).
01 (referred to as a crown shape), the pressure distribution between the transfer roller 44 and the backup roller 41 is higher on the center side, and as shown in FIG. In the paper 43, undulations occur due to the force directed toward the center side where the pressure is higher, and furthermore, wrinkles 45 and
. . and is sent out from between the transfer roller 44 and the backup roller 41. In this state, the paper 4 is transferred to the intermediate transfer heald 42 during transfer.
3 is not maintained in a uniform state of adhesion, resulting in a problem of poor transfer.

The present invention has been made in view of the above, and an object of the present invention is to reduce the occurrence of paper waviness during transfer, thereby reducing transfer defects, and further simplifying the configuration for this purpose. An object of the present invention is to provide a transfer roller device that can be used as a transfer roller device.

[Means to solve the problem]

Therefore, the transfer roller device according to claim 1 of the present invention is provided with paper fed from a paper conveyance means such as a paper feed roller,
In a transfer roller device that transfers the image on the image forming body to paper while the image forming body such as the intermediate transfer belt is sandwiched between a transfer roller and a bank amplifier roller and is fed out while pressurizing them, both ends in the axial direction The l# characteristic is that the back unroller is provided with an outer circumferential surface member made of an elastic body divided into a plurality of cylindrical members with a larger number of divisions per unit length toward the center. .

Further, the transfer roller device according to claim 2 of the present invention sandwiches the paper and the image forming body supplied from the paper conveyance means between the transfer roller and the backup roller, and while feeding them while pressurizing them, the image forming body is In a transfer roller device that transfers an image on a forming body to a sheet of paper, the backup roller is provided with an outer circumferential surface member formed of an elastic body having a larger elastic modulus on the center side than on both ends in the axial direction. It is characterized by

Note that in this specification, the word "paper" means a sheet-like material that is not limited to paper.

[For production]

According to the configuration of claim 1 above, when a large amount of elastic displacement occurs on the outer circumferential surface member of the pack unroller on the axially central side, this outer circumferential surface member is divided into a plurality of cylindrical members. A discontinuous difference occurs in the amount of elastic displacement between adjacent cylindrical members on both sides of each close end surface, and therefore a discontinuous difference occurs in the elastic reaction force between each close end surface. Therefore, frictional force is generated on these close end surfaces,
As this frictional force acts as a force against the elastic reaction force, a force lower than the force corresponding to the amount of elastic displacement of each cylindrical member acts as a reaction force on the member pressing it. In the above case, by increasing the number of divisions on the center side, and therefore increasing the number of division surfaces where the above-mentioned frictional force occurs, the center side, which has a large amount of elastic displacement, is moved from the center side to both ends. It is possible to create a state in which a reaction force is smaller than that of the above. As a result, even when the 0.01 crown-shaped transfer roller is pressed against the bank-up roller, the contact pressure on the axial center side with the transfer roller can be made smaller than on both ends. Become. As a result, contrary to the conventional method, the paper is conveyed while being subjected to tensile force from the center to both sides, which suppresses the occurrence of wrinkles that have been common in the past, resulting in poor transfer. is reduced. In this way, with a simple configuration in which the outer circumferential surface member made of the elastic body of the backup roller is divided, it is possible to maintain the conveyance state of the paper with high pressure on both ends in the axial direction, thereby preventing transfer defects. It is possible to reduce the

Further, according to the configuration of claim 2, since the backup roller is formed of an elastic body having a larger elastic modulus on both end sides than on the axial center side, the 0.01 crown-shaped transfer roller Even when pressing, it is possible to make the reaction force proportional to the amount of elastic displacement and the elastic coefficient smaller on the center side than on both ends. Therefore, in this case as well, a simple configuration in which the outer circumferential surface member of the back amp roller is made of elastic bodies with different elastic modulus increases the pressing pressure at both ends in the axial direction, thereby suppressing the occurrence of wrinkles. It is possible to maintain the state in which the paper is conveyed, and it is possible to reduce transfer defects.

[Embodiment 1] An embodiment of the present invention will be described below based on FIGS. 1 to 4. Note that this embodiment exemplifies a case where the transfer roller device is applied to a full-color copying machine.

As shown in Figure 3, a full-color copying machine has an original IO
An optical system 2 for exposure is provided below a document table glass 1 on which a document is placed. This optical system 2 includes an exposure lamp 2a that irradiates light toward the original 10, and an exposure lamp 2a that emits light toward the original 10.
A plurality of reflecting mirrors 2b, which guide the reflected light from the light onto the photoreceptor heald 3 as shown by the dotted chain line in the figure, an imaging lens 2c arranged on the optical path, and three primary colors (red, green, blue). The filter device 2d has a color filter.

The photoreceptor heald 3 is an organic photoreceptor (OPC photoreceptor).
A hook is provided between a driving roller 4a and a driven roller 4b which are arranged parallel to each other at a constant interval. Near the center of the upper surface of this photoreceptor belt 3 are developer tanks 5a, 5b,
5c are arranged in a non-contact manner, and these developing tanks 5a to 5c are arranged in a non-contact manner.
5c stores yellow, cyan, and magenta developers, respectively. Further, around the driven roller 4b side of the photoreceptor belt 3, in addition to a charging charger 6a and a static elimination lamp 6b, a device for removing toner remaining on the photoreceptor belt 3 is provided on the lower surface of the photoreceptor belt 3. A cleaner 7 is provided.

On the other hand, a transfer intermediate device 11 is provided on the driving roller 4a side. This intermediate transfer device 11 is provided with an intermediate transfer heald 12 as an image forming body, and this intermediate transfer heald 12 includes a driving roller 13a and a first driven roller 1.
3b, and a second driven roller (hereinafter referred to as a backup roller) 13c which functions as a backup roller for a transfer roller 25, which will be described later. Further, in a portion of the intermediate transfer belt 12 between the driving roller 13a and the first driven roller 13b,
The drive roller 4a side of the photoreceptor heald 3 is in pressure contact, and the monochromatic toner image formed on the photoreceptor belt 3 is transferred onto the intermediate transfer belt 12 on the back side of the intermediate transfer belt 12 at this pressure contact portion. An intermediate transfer roller 14 is provided for this purpose. In addition, the drive roller 13a
A cleaner 15 for removing toner remaining on the intermediate transfer belt 12 is arranged near the intermediate transfer belt 12 .

In the case of the figure, two paper feed cassettes 21 are installed at a position on the right side of the transfer intermediate device 11 in the figure, and any selected paper feed cassette 2
The paper 22 taken out from the transfer intermediate device 1 [11] is transferred to the backup roller 13c in the transfer intermediate device 1 [11] and the backup roller 13c by being transported by the paper feed roller (paper transport means) 23 and guided by the paper guide 24. The transfer roller 25 is arranged to face the transfer roller 25 . This transfer roller 25 sandwiches the paper 22 together with the intermediate transfer belt 12 between it and the backup roller 13c and sends it out to the left.
It has a function of transferring the full-color toner image on the intermediate transfer belt 12 to the paper 22, the details of which will be explained later.

On the left side of the transfer roller 25 in the figure, there is a peeling plate 2 for peeling the paper 22 from the intermediate transfer heald 12.
6 is provided, and furthermore, a paper conveyance heald 27,
A fixing device 28 for fixing the full-color toner image on the paper 22 to the paper 22 is provided at the end of the paper conveyance heald 27 .

In the above configuration, to briefly explain the operation of full-color copying, the light emitted from the exposure lamp 2a is applied to the document 1.
0, this reflected light passes through an imaging lens 2c and a filter device 2d through a reflecting mirror 2b..., and the filter device 2d extracts only light of a specific color component corresponding to each color filter and is exposed to light. Irradiation is applied onto the body heald 3.

Through this exposure operation, a latent image is formed on the photoreceptor heald 3, which is developed with one of the developers in the developing tanks 5a to 5c, which is a complementary color to the specific color light, to form a monochromatic toner image in an area that is not irradiated with light. This monochrome toner image is then intermediately transferred onto the intermediate transfer belt 12 by the intermediate transfer roller 14. By performing the above operations of exposure → monochrome development → intermediate transfer for each color filter (red, green, blue), intermediate transfer is performed three times (yellow, magenta, cyan) to the intermediate transfer heald 12. A full-color toner image is formed on the intermediate transfer heald 12 by overlapping monochrome toner for each color component.

When a full-color toner image is formed on the intermediate transfer heald 12, the paper 22 that has been taken out from one of the paper feed trays 21 and 21 and has been waiting at a predetermined position is moved between the hack up roller 13c and the transfer roller 25. sent between
A full color toner image is transferred onto the paper 22 as it passes between these. The paper 22 on which the full-color toner image has been transferred is introduced into a fixing device 28 by a paper transport belt 27, and the full-color toner image is fixed.

By the way, the intermediate transfer held 12 as described above is used as the dispute paper 2.
Transferring the full color toner image to intermediate transfer held 1
2 and the paper 22, and press the transfer roller 25 against the backup roller 13c, thereby causing the intermediate transfer bell) 1
This is performed by applying a voltage while pressing the full-color toner image on paper 22 against paper 22. For this reason, as shown in FIG. 4, the transfer roller 25 is mounted so that it can move forward and backward in the direction toward the backup roller 13c, as shown by arrow A in the figure, and is also able to move forward and backward in the direction toward the backup roller 13c. is sometimes rotatably supported as a driven roller that rotates as the intermediate transfer belt 12 moves. Further, this transfer roller 25 is made of metal such as stainless steel, and an electric current a! A transfer voltage is applied from 31. Note that between the hack unroller 13c and the first driven roller 13b,
More specifically, the first driven roller 13 is approximately 10 to 18 mm from the point where the transfer roller 25 contacts the backup roller 13c with the intermediate transfer heald 12 and the paper 22 in between.
A grounded back electrode roller 32 is provided at a position on the b side. This back electrode roller 32 is made of stainless steel and has a diameter of about 8 mm, for example, and extends over the entire width of the intermediate transfer belt 12. By slidingly contacting the intermediate transfer heald 12 from the back side, the back electrode roller 32 extends over the entire width of the intermediate transfer belt 12.
is held at ground potential.

-4, As shown in the first part, the pack unroller 13c has a shaft center member 3 made of a steel pipe with an outer diameter of 18 mm, for example.
An outer peripheral member 36 having a rubber hardness of 40°, for example, is fitted onto the outer periphery of the rubber member 5. The outer circumferential member 36 is divided into 14 cylindrical members 36a, in the case of the figure, on a plurality of planes perpendicular to the axis. Further, the axial lengths of these cylindrical members 36a are configured to be shorter toward the center, and gradually longer toward both ends while maintaining a symmetrical relationship on both sides. To illustrate these dimensions, the axial length of each of the six central cylindrical members 36a is 10 mm, and the cylindrical members 36 outside these
a... are sequentially lengthened to 20 mm, 30 mm, and 40 mm, and the cylindrical members 36a and 36a at both ends are each 51 m long.
m is a back unroller 13c with a total length of 342 mm.
An outer circumferential member 36 is configured.

FIG. 2 shows a transfer roller 2 attached to a bank amplifier roller 13c configured by providing an outer circumferential member 36 having a divided configuration as described above.
5 is pressed with a predetermined force and the sheet sandwiched between the sheets is pulled out. An example of the test results of the relationship between the position in the axial direction and the pulling force is shown. In this case, the transfer roller 25 has the above-mentioned 0, 01 crown shape. In addition, the same figure also shows the test results of a conventional non-divided hack unroller using a chain double-dashed line. However, in the above example,
The distribution is smaller toward the center than on both sides.

That is, when the transfer roller 25 as described above is pressed, the outer peripheral member 36 undergoes a large elastic deformation at the center thereof. In this case, since the outer peripheral member 36 is divided into a plurality of cylindrical members 36a..., the amount of elastic displacement on both sides of each close end surface between the adjacent cylindrical members 36a is discontinuous. Therefore, the elastic reaction force corresponding to the amount of elastic deformation also becomes discontinuous between the close contact end surfaces. Therefore, a frictional force is generated on these close contact end surfaces, and this frictional force acts as a force that resists the elastic reaction force, so that the force from each cylindrical member 36a is greater than the force corresponding to the amount of elastic deformation. The reduced force acts as a reaction force on the transfer roller 25 pressed against it. and,
In the above, the center side is divided densely, so that a large frictional force acting against the elastic reaction force acts on the center side. As a result, the pull-out force distribution is smaller at the center side, where the amount of elastic deformation is larger, than at both end sides.

Conventionally, the pressure of the paper against the intermediate transfer heddle was greater at the center, which caused wrinkles due to the undulation of the paper, for example, when transporting weak paper.However, according to the above, the transfer roller Even if the roller 25 has the above-mentioned 0.01 crown shape, contrary to the conventional case, the transfer roller 25 and the bank unroller 13c are in contact with the paper 22 with a large pressure on both sides.
The paper 22 is conveyed between the two. In this case, the paper 2 is subjected to tensile force from the center toward both sides.
Since the paper 22 is transported while maintaining uniform contact with the intermediate transfer belt 12 over its entire width, the occurrence of transfer defects is reduced.

[Embodiment 2] Another embodiment of the present invention will be described below based on FIG. In this embodiment, the only difference is the structure of the bank amplifier roller from the previous embodiment, so explanation of the structure other than this backup roller will be omitted, and the members are the same as those shown in the drawings of the above embodiment. Components having the same functions as those shown in FIG.

The hack unroller 13C in this embodiment is the fifth
As shown in the figure, the outer peripheral member 36 is connected to the central cylindrical member 36.
c, and side cylindrical members 36s and 36s on both sides of the central cylindrical member 36c. For example, the axial length of the central cylindrical member 36c is 160 m.
m, the side cylindrical members 36s and 36s are each 91 mm in length, and by connecting them in the axial direction, the outer peripheral member 36 having an outer diameter of, for example, 24 mm and a total length of 342 mm can be fitted with a 13c is configured. In this case, the central cylindrical member 3.6c is made of silicone rubber, for example, with a rubber hardness of 40°, and the side cylindrical members 36s are made of silicone rubber, for example, with a rubber hardness of 60°.

In this case, for example, when the 0.01 crown-shaped transfer roller is pressed, the amount of elastic deformation is sometimes larger on the axial center side, but as described above, the center cylindrical member 36c has a larger elastic deformation on the side. By being made of an elastic body with a smaller elastic modulus than the cylindrical members 36S and 36s, in a test to measure the paper pullout force when the transfer roller 25 is pressed against the backup roller 13c with a specified force, the center side is more Almost the same distribution results as in the above embodiment are obtained, in which the distribution is smaller than that at both ends. Therefore, in this case as well, paper 2
2, since it is possible to maintain a conveying state in which a tensile force is applied from the center toward both sides, the occurrence of transfer defects is reduced.

Although each of the above embodiments has been described using a transfer roller device incorporated in a full-color copying machine as an example, the transfer roller device of the present invention can be applied to other printer devices with almost the same configuration. It is possible.

〔Effect of the invention〕

As described above, the transfer roller device according to claim 1 of the present invention has a structure in which the elastic body is divided into a plurality of cylindrical members, with the number of divisions per unit length being larger on the center side than on both ends in the axial direction. In this configuration, the outer circumferential surface member consisting of the following is provided on the backup roller.

As a result, from the outer circumferential surface member, a force corresponding to the amount of elastic deformation is greatly reduced on the center side where the number of divided surfaces is large, and a force that is significantly reduced acts on the paper as a pressing pressure. Even in the case of the 0.01 crown shape, the paper conveyance state in which the pressure at both ends in the axial direction is greater than that at the center can be maintained with a simple configuration in which the outer circumferential surface member is divided. As a result, wrinkles that conventionally occur are suppressed, and transfer defects are reduced.

Further, the transfer roller device according to claim 2 is configured such that the pack unroller is provided with an outer circumferential surface member formed of an elastic body having a larger elastic modulus on the center side than on both ends in the axial direction. be.

As a result, even when pressing the 0.01 crown-shaped transfer roller, for example, the reaction force proportional to the amount of elastic displacement and elastic coefficient can be made smaller on the center side than on both ends. It is possible. Therefore, it is possible to maintain a conveyance state that does not cause waviness or wrinkles in the paper with a simple configuration in which the outer peripheral member is made of elastic bodies with different elastic coefficients, and as a result, it is possible to reduce transfer defects. play.

[Brief explanation of drawings]

1 to 4 show one embodiment of the present invention. FIG. 1 is a perspective view of the backup roller. FIG. 2 is a graph showing an example of the results of measuring the pulling force of the paper sandwiched between the backup roller and the transfer roller while changing the axial position. FIG. 3 is a schematic diagram showing a simplified internal structure of a full-color copying machine. FIG. 4 is a schematic diagram showing the vicinity of the transfer roller in the full-color copying machine. FIG. 5 shows another embodiment of the present invention, and is a perspective view of a backup roller. FIGS. 6 and 7 show conventional examples. FIG. 6 is a perspective view showing the transfer and conveyance state of paper. FIG. 7 is a front view showing an example of the shape of the transfer roller. 12 is an intermediate transfer belt (image forming body), 13c is a backup roller, 22 is paper, 23 is a paper feed roller (paper transport means), 25 is a transfer roller, 36 is an outer peripheral member, and 36a is a cylindrical member. 411Q 511th

Claims (1)

[Claims] 1. The paper and the image forming body supplied from the paper conveying means are sandwiched between a transfer roller and a backup roller, and while they are being fed out while being pressurized, the image on the image forming body is transferred to the paper. In the transfer roller device for transferring, the backup roller is provided with an outer peripheral surface member made of an elastic body divided into a plurality of cylindrical members with a larger number of divisions per unit length on the center side than on both ends in the axial direction. A transfer roller device characterized by: 2. In a transfer roller device that pinches the paper and the image forming body supplied from the paper conveyance means between a transfer roller and a backup roller, and transfers the image on the image forming body to the paper while feeding them while pressurizing them. . A transfer roller device, wherein the backup roller is provided with an outer circumferential surface member formed of an elastic body having a larger elastic modulus on the center side than on both ends in the axial direction.