JP4336152B2 - Transfer device and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transfer apparatus and an image forming apparatus that transfer a toner image to a transfer target by a roller to which a bias voltage is applied.
[0002]
[Prior art]
An electrophotographic image forming apparatus that forms an electrostatic latent image on a photosensitive member with a laser beam or the like in accordance with an image signal, and transfers the electrostatic latent image to a transfer material or the like as a toner image is a copier, printer Widely used in facsimiles. In recent years, a color image forming apparatus for transferring a color image to a transfer material or the like using a color image signal has also been provided.
[0003]
A typical method of color image formation includes an intermediate transfer method in which toner images of different colors formed on a plurality of photosensitive members are transferred while being superimposed on an intermediate transfer member, and then transferred to a transfer material in a batch. There is a direct transfer system in which toner images of different colors formed on a photoconductor as an image carrier are transferred while being directly superimposed on a transfer material. Since a plurality of photoconductors are arranged side by side facing a transfer material or an intermediate transfer body, this is called a tandem method, and yellow (Y), magenta (M), cyan (C), and black (K) for each photoconductor. For each color, an electrophotographic process such as electrostatic latent image formation and development is executed, and the image is transferred onto a running intermediate transfer member in the intermediate transfer method, and transferred onto a running transfer material in the direct transfer method. To do. The tandem color image forming apparatus using each of these methods supports an endless intermediate transfer belt that receives and carries an image from a photoreceptor in the intermediate transfer method, and supports a transfer material in the direct transfer method. In general, an endless conveyor belt that travels while moving is employed. Each photoconductor is provided with a transfer roller so that the intermediate transfer belt or the conveyance belt is pressed against the photoconductor. In the intermediate transfer system, a fixing roller pair is provided as a fixing device for fixing the image on the transfer material by pressing the transfer material on the intermediate transfer belt on which the toner image is transferred. One of each transfer roller and fixing roller pair is marked with a high voltage in order to increase the transfer efficiency of the toner image to the intermediate transfer belt or transfer material.
[0004]
However, especially in the intermediate transfer belt, since the material is made of a dielectric material having a moderate electrical resistance, leakage is likely to occur between the axial end portions of the transfer roller and the intermediate transfer belt. As a result, the high voltage applied to the transfer roller drops, and the toner image corresponding to the voltage drop is not transferred to the transfer material on the intermediate transfer belt or transport roller, or to the transfer material on the fixing roller pair. There is a problem that is likely to occur.
[0005]
Therefore, for example, in the invention described in Patent Document 1, it is proposed to cover an insulating member on the surface of the intermediate transfer belt that contacts both ends of the transfer roller in the axial direction. Further, in the invention described in Patent Document 2, a cover is attached to the roller end surface to prevent creeping leakage from the roller end portion.
[0006]
[Patent Document 1]
Japanese Patent No. 2936812 [0007]
[Patent Document 2]
Japanese Patent No. 3169030 [0008]
[Problems to be solved by the invention]
However, in the invention described in Patent Document 1, since the surface of the intermediate transfer belt is in contact with not only the transfer roller but also the photosensitive member and the intermediate transfer belt cleaning device, the insulating member is provided outside the member that contacts the intermediate transfer belt. If the belt is provided so as not to come into contact, the intermediate transfer belt and the apparatus are enlarged accordingly. Further, when the insulating member comes into contact with the photosensitive member or the intermediate transfer belt cleaning device, they are rubbed against each other, so that they are worn out or twisted, making it difficult to extend the life.
[0009]
On the other hand, the invention described in Patent Document 2 prevents creeping leakage from the roller end, but prevents leakage between the intermediate transfer belt and the bias roller that applies a voltage to the intermediate transfer belt. Not.
[0010]
There is little or no difference in linear velocity between the photoconductor and the intermediate transfer belt, so there is little wear or twist. However, since the photosensitive layer of the photosensitive member is thin, the photosensitive layer becomes thin even with a small amount of wear, and the place facing the vicinity of the end of the insulating layer of the intermediate transfer belt is between the conductive layer of the photosensitive member base layer and the intermediate transfer belt. Leakage is likely to occur. As a result, it is difficult to extend the life of the photoreceptor.
[0011]
Further, in the intermediate transfer belt cleaning device, the position of the insulating member of the intermediate transfer belt is a position facing the end of the cleaning member or the toner leakage prevention seal of the cleaning device container, and a linear velocity difference is generated from the intermediate transfer belt. Therefore, the insulating member of the intermediate transfer belt is greatly worn and twisted, and it is difficult to extend the life of the insulating member for preventing leakage.
[0012]
The present invention has been made in view of such a state of the art, and its purpose is to prevent leakage between the transfer roller and the intermediate transfer belt or the transfer material conveying belt and obtain a good image, It is an object of the present invention to provide a transfer device and an image forming apparatus capable of preventing the wear and wrinkling due to rubbing and extending the life of the apparatus.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the first means includes a core metal to which a bias voltage having a polarity opposite to the polarity of the toner image on the image carrier is applied from a high voltage power source, and an intermediate resistance layer covering the periphery of the core metal. The primary bias roller is configured to apply a bias to the inner surface of the intermediate transfer belt, which does not have insulation, and transfer the toner image on the image carrier to the intermediate transfer belt. A bias is applied to the inner surface of the intermediate transfer belt by a repulsive transfer bias roller composed of a core bar to which a bias voltage having the same polarity as that of the toner image is applied from a high-voltage power source and an intermediate resistance layer covering the periphery of the core bar. A transfer device for applying and transferring a toner image on the intermediate transfer belt to a transfer material ,
By the running of the intermediate transfer belt on the inner surface of the intermediate transfer belt, both end surfaces of the intermediate resistance layer of the primary bias roller can be opposed to both end surfaces of the intermediate resistance layer of the repulsive transfer bias roller. A belt-like insulating member is provided at both ends of the inner surface of the intermediate transfer belt so as to cover the entire portion.
[0014]
Second means, in the first means, the image bearing member is a plurality arranged along the running direction of the intermediate transfer belt, each image bearing member of the plurality, the polarity of the toner image on the image bearing member reverse the polarity of the bias voltage by the primary bias rollers composed of a resistive layer in covering around the metal core and metal core that has been applied from high-voltage power supply, while themselves during have such an insulating property transfer belt A core bar to which a bias voltage having the same polarity as the polarity of the toner image on the intermediate transfer belt is applied from a high-voltage power source is applied to the inner surface of the image transfer member to transfer the toner image on the image carrier to the intermediate transfer belt. And a repulsive transfer bias roller comprising a middle resistance layer covering the periphery of the metal core, a bias is applied to the inner surface of the intermediate transfer belt and a toner image on the intermediate transfer belt is transferred to a transfer material a is, the intermediate transfer bell And each traveling through both end surfaces in the resistance layer of the intermediate transfer belt wherein all the primary bias rollers on the inner surface of the further, can be a portion facing the respective end surfaces of the resistance layer in said repulsive bias roller A belt-like insulating member is provided at both ends of the inner surface of the intermediate transfer belt so as to cover the entire portion.
[0015]
The third means is an axial direction in which the intermediate resistance layer covering the periphery of the core metal of the primary bias roller is opposed to the insulating member in the first means or the second means so as not to contact the insulating member. It is characterized in that the outer diameters at both ends are small .
[0016]
According to a fourth means, in any one of the first to third means, the middle resistance layer covering the periphery of the core of the repulsive force transfer bias roller faces the insulating member so as not to contact the insulating member. It is characterized in that the outer diameters at both ends in the axial direction are reduced .
[0017]
The fifth means is a writing means for writing image data on an image carrier, an image forming means for forming a latent image by the writing means and developing it to form a visible image, and an image visualized by the image forming means. And an image forming apparatus configured to include a transfer device according to first to third means for transferring the image onto a transfer material .
[0022]
In the following embodiments, the image carrier is the photoreceptors 40Y, 40C, 40M, and 40K, the transfer body is the intermediate transfer belt 10, the rollers are the primary bias rollers 62Y, 62C, 62M, and 62K, and the insulating member. Is the insulating member 203, the core is the core 201, the middle resistance layer is the elastic body 202, the repulsive transfer bias roller is the repulsive transfer bias roller 16, the writing means is the exposure device 21, and the image forming means is the image forming apparatus. 18Y, 18C, 18M, and 18K respectively.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the case where the present invention is applied to an intermediate transfer type color copying machine is taken as an example. FIG. 2 is a diagram schematically showing the overall configuration of the color copying machine according to the embodiment of the present invention.
[0024]
In FIG. 2, reference numeral 100 is a copying apparatus main body, 200 is a paper feed table on which it is placed, 300 is a scanner mounted on the copying apparatus main body 100, and 400 is an automatic document feeder (ADF) mounted thereon.
[0025]
In the copying apparatus main body 100, an endless intermediate transfer belt 10 is wound around the first and second support rollers 14 and 15 and the repulsive force transfer bias roller 16 at the center. In FIG. 2, it can be rotated and conveyed clockwise. In this embodiment, an intermediate transfer member cleaning device 17 for removing residual toner remaining on the intermediate transfer belt 10 after image transfer is provided on the left side of the second support roller 15 in the drawing.
[0026]
Further, on the intermediate transfer belt 10 stretched between the first support roller 14 and the second support roller 15, along the conveyance direction, yellow (Y), cyan (C), magenta (M), Four image forming apparatuses 18Y, 18C, 18M, and 18K for forming a black (K) monochrome image are arranged side by side to constitute the image forming unit 20. Each of the image forming apparatuses 18Y, 18C, 18M, and 18K includes a drum-shaped photoconductor 40Y, 40C, 40M, and 40K, and a charging device, a developing device, a photoconductor cleaning device, a static eliminator, and the like disposed around the photoconductors. It consists of an image unit. Primary bias rollers 62Y, 62C, 62M, and 62K are provided so as to come into contact with the back surface of the intermediate transfer belt 10 at positions facing the photoconductors 40Y, 40C, 40M, and 40K, respectively. An exposure device 21 is provided on the image forming unit 20. The alphabet after the reference number represents a color, and is distinguished by adding Y for yellow, C for cyan, M for magenta, and K for black.
[0027]
On the other hand, a secondary transfer device 22 is provided on the opposite side of the intermediate transfer belt 10 from the image forming unit 20. In the illustrated example, the secondary transfer device 22 is configured by spanning a secondary transfer belt 24 that is an endless belt between a repulsive transfer bias roller 16 and two rollers 23. One of the rollers 23 is disposed so as to press against the repulsive transfer bias roller 16 via the intermediate transfer belt 10, and the image on the intermediate transfer belt 10 is transferred onto the transfer paper (transfer material) 1.
[0028]
A fixing device 25 for fixing the transfer image on the transfer paper to the transfer paper 1 is provided downstream of the secondary transfer device 22 in the transfer conveyance direction. The fixing device 25 is configured to press a pressure roller 27 against a fixing belt 26 that is an endless belt. The secondary transfer device 22 described above also has a transfer paper transport function for transporting the transfer paper 1 after image transfer to the fixing device 25. Under the secondary transfer device 22 and the fixing device 25, a transfer paper reversing device 28 for reversing the transfer paper 1 to record images on both sides of the transfer paper 1 is provided in parallel with the image forming unit 20.
[0029]
When making a copy using this color copying machine, set the document on the document table 30 of the automatic document feeder 400 or open the automatic document feeder 400 and set the document on the contact glass 32 of the scanner 300. Then, the automatic document feeder 400 is closed and pressed by it.
[0030]
When a start switch (not shown) is pressed, when a document is set on the automatic document feeder 400, the document is transported and moved onto the contact glass 32, and then the document is set on the other contact glass 32. When this occurs, the scanner 300 is immediately driven to travel on the first traveling body 33 and the second traveling body 34. Then, the first traveling body 33 emits light from the light source and further reflects the reflected light from the document surface toward the second traveling body 34, and is reflected by the mirror of the second traveling body 34 and passes through the imaging lens 35. The document is placed in the reading sensor 36 and the original content is read.
[0031]
When the start switch is pressed, the first support roller 14 that is a drive roller is driven to rotate, and the remaining two follower rollers 15 and the repulsive transfer bias roller 16 are driven and rotated. The transfer belt 10 is rotated and conveyed. At the same time, the individual image forming means 18 rotates the photoconductor 40 to form black, yellow, magenta, and cyan monochrome images on each photoconductor 40. Then, along with the conveyance of the intermediate transfer belt 10, the monochrome images are sequentially transferred to form a composite color image on the intermediate transfer belt 10.
[0032]
On the other hand, when the start switch is pressed, one of the paper feed rollers 42 of the paper feed table 200 is selectively rotated, the transfer paper 1 is fed out from one of the paper feed cassettes 44 provided in multiple stages in the paper bank 43, and the separation roller The sheet is separated one by one at 45 and put into the sheet feeding path 46, conveyed by the conveying roller 47, guided to the sheet feeding path 48 in the copying machine main body 100, abutted against the registration roller 49 and stopped. In addition to this, the sheet feeding roller 50 is rotated to feed the transfer paper 1 on the manual feed tray 51, separated one by one by the separation roller 52, put into the manual feed path 53, and pushed against the registration roller 49. You may make it stop.
[0033]
Then, the registration roller 49 is rotated in synchronization with the composite color image on the intermediate transfer belt 10, the transfer paper 1 is fed between the intermediate transfer belt 10 and the secondary transfer device 22, and transferred by the secondary transfer device 22. Then, a color image is recorded on the transfer paper 1.
[0034]
The transfer paper 1 after image transfer is fed to the fixing device 25 by the secondary transfer device 22, and heat and pressure are applied by the fixing device 25 to fix the transferred image, and then the switching paper 55 is switched by the switching claw 55 and discharged by the discharge roller 56. The paper is discharged and stacked on the paper discharge tray 57. At this time, it is switched by the switching claw 55 and is put into the transfer paper reversing device 28, where it is reversed and led again to the transfer position, an image is recorded also on the back surface, and then discharged onto the discharge tray 57 by the discharge roller 56. You can also
[0035]
On the other hand, the intermediate transfer belt 10 after image transfer is removed by the intermediate transfer body cleaning device 17 to remove residual toner remaining on the intermediate transfer belt 10 after image transfer, and prepares for image formation by the image forming unit 20 again. In general, the registration roller 49 is often used while being grounded. However, a bias can be applied to remove the paper dust of the transfer paper 1.
[0036]
FIG. 1 is a perspective view showing in detail a part of the characteristic part in the embodiment of the present invention. In this figure, the back surface of the intermediate transfer belt 10 is shown facing upward. As described above, the primary bias rollers 62Y, 62C, 62M, and 62K serve as the transfer electric field forming means for forming transfer electric fields at the transfer positions of the photoconductors 40Y, 40C, 40M, and 40K. They are provided at positions facing 40M and 40K so as to contact the back surface of the intermediate transfer belt 10, respectively. These primary bias rollers 62Y, 62C, 62M, and 62K are composed of a conductive core bar 201 and an elastic body 202 made of a medium resistance rubber or the like. The cores 201 of the primary bias rollers 62Y, 62C, 62M, and 62K are applied with a voltage having a polarity opposite to that of the toner images on the photoreceptors 40Y, 40C, 40M, and 40K from a high voltage power source (not shown) during image formation. . Similarly to the primary bias rollers 62Y, 62C, 62M, and 62K, the repulsive force transfer bias roller 16 includes a cored bar 201 and an elastic body 202 made of a medium resistance rubber or the like. A voltage having the same polarity as the toner image on the intermediate transfer belt 10 is applied from a high voltage power source (not shown).
[0037]
On both ends of the intermediate transfer belt 10 in the direction orthogonal to the running direction (both edges of the intermediate transfer belt) and on the back surface (inner side of the intermediate transfer belt) with respect to the image forming surface outside the image surface, polyethylene, A strip-shaped insulating member 203 made of polyester or the like is provided. Axial direction of a total of five rollers including four primary bias rollers 62Y, 62C, 62M and 62K and one repulsive transfer bias roller 16 disposed at positions facing the photoconductors 40Y, 40C, 40M and 40K. Both end portions are arranged so as to contact the insulating member 203 on the back surface of the intermediate transfer belt 10.
[0038]
Thus, the axial end portions of the four primary bias rollers 62Y, 62C, 62M, and 62K and the single repulsive bias roller 16 are in contact with the insulating member 203 provided on the inner surface of the intermediate transfer belt 10. Therefore, the leakage of voltage from these rollers can be prevented, and the insulating member 203 includes the first and second support rollers 14 and 15, the repulsive transfer bias roller 16, and the primary bias rollers 62Y, 62C, The first and second support rollers 14 and 15 that pull the intermediate transfer belt 10 and the repulsive transfer bias roller 16 and the intermediate transfer belt 10 are rotated without any difference in linear speed. There is little abrasion of the insulating member 203, and the leak prevention effect by the insulating member 203 can be kept long. Furthermore, it is not necessary to provide a leak prevention member for each of the bias rollers, and a leak prevention member can prevent leakage of the end surfaces in the axial direction of all the bias rollers. Can do.
[0039]
Note that the outer diameters of the first and second support rollers 14 and 15 that pull the intermediate transfer belt 10 and the end portions in the axial direction of the repulsive transfer bias roller 16 that face the insulating member 203 are reduced so that the insulating member 203 By preventing contact, the life can be further extended.
[0040]
In the above-described embodiment, the indirect method of the color copying machine is taken as an example, but the present invention is applied to the direct method color copying machine described in the prior art as long as it is a copying machine having a bias roller. be able to.
[0041]
【The invention's effect】
As described above, according to the present invention, since the insulating member is provided on the back surface of the transferred object, the insulating member comes in contact with a part other than the bias roller. Since the body rotates with no difference in linear velocity, there is little wear and the life of the insulating member for preventing leakage can be extended.
[Brief description of the drawings]
FIG. 1 is a perspective view showing in detail a part of a characteristic part in an embodiment of the present invention.
FIG. 2 is a diagram schematically showing an overall configuration of a color copying machine according to an embodiment of the present invention.
[Explanation of symbols]
10 Intermediate transfer belt 16 Repulsive transfer bias rollers 18Y, 18C, 18M, 18K Image forming means 20 Tandem image forming unit 22 Secondary transfer device 25 Fixing devices 40Y, 40C, 40M, 40K Photoconductors 62Y, 62C, 62M, 62K Primary Bias roller 100 Copier main body 200 Paper feed table 300 Scanner 201 Core metal 202 Elastic body 203 Insulating member

Claims (5)

The primary bias roller is composed of a core metal to which a bias voltage having a polarity opposite to the polarity of the toner image on the image carrier is applied from a high-voltage power source, and a middle resistance layer covering the core metal. A bias voltage is applied to the inner surface of the intermediate transfer belt that does not have the toner, the toner image on the image carrier is transferred to the intermediate transfer belt, and a bias voltage having the same polarity as the polarity of the toner image on the intermediate transfer belt is a high voltage power source. A bias is applied to the inner surface of the intermediate transfer belt by a repulsive transfer bias roller composed of a cored bar applied from and a middle resistance layer covering the periphery of the cored bar to transfer the toner image on the intermediate transfer belt A transfer device for transferring to a material ,
By the running of the intermediate transfer belt on the inner surface of the intermediate transfer belt, both end surfaces of the intermediate resistance layer of the primary bias roller can be opposed to both end surfaces of the intermediate resistance layer of the repulsive transfer bias roller. A transfer apparatus comprising a band-shaped insulating member provided at both ends of the inner surface of the intermediate transfer belt so as to cover the entire portion. Said image bearing member is a plurality arranged along the running direction of the intermediate transfer belt, each image bearing member of the plurality of bias voltages of polarity opposite the polarity of the toner image on the image bearing member is applied from a high voltage power source by the primary bias rollers composed of a resistive layer in covering around the metal core and metal core, itself has a bias is applied to the inner surface of the stomach during the transfer belts has an insulating property, the image bearing member A core metal to which a bias voltage having the same polarity as the polarity of the toner image on the intermediate transfer belt is applied from a high voltage power source and an intermediate resistance layer covering the periphery of the core metal; A transfer device configured to apply a bias to the inner surface of the intermediate transfer belt by a repulsive transfer bias roller configured by transferring a toner image on the intermediate transfer belt to a transfer material ;
Due to the running of the intermediate transfer belt, both end surfaces of the intermediate resistance layers of all the primary bias rollers on the inner surface of the intermediate transfer belt, and further, both end surfaces of the intermediate resistance layers of the repulsive transfer bias roller, respectively. The transfer apparatus according to claim 1, wherein strip-shaped insulating members are provided at both end portions of the inner surface of the intermediate transfer belt so as to cover all the portions that can be opposed portions. Resistive layer in covering the periphery of the core metal of the primary bias roller claims, characterized in that the outer diameter of the axial end portion of the insulating member and the counter so as not to contact with the insulating member is smaller The transfer apparatus according to 1 or 2 . Resistive layer in covering the periphery of the metal core of the repulsive transfer bias roller, billed, characterized in that the outer diameter of the axial end portion of the insulating member and the counter so as not to contact with the insulating member is smaller Item 4. The transfer device according to any one of Items 1 to 3 . Writing means for writing image data to the image carrier;
An image forming means for forming a latent image by the writing means and developing to form a visible image;
The transfer device according to claim 1, wherein the image visualized by the image forming unit is transferred to a transfer material;
An image forming apparatus comprising the.

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