KR20060113161A - Image transferring unit and electrophotographic image forming apparatus with the same - Google Patents

Abstract

An image transfer unit and an electro photographic type image forming apparatus with the same are provided to inhibit contamination of a paper adsorption roller and a transfer belt. The second roller(145) is arranged in parallel to the lower portion of the first roller(143). A transfer belt(141) is wound to the first and second rollers and circulates. Transfer rollers(150Y,150M,150C,150K) are arranged between the first and second rollers and oppositely to photosensitive media. The transfer belt is interposed between the transfer rollers. A paper adsorption roller(152) is arranged oppositely to the second roller. A protection member(155) covers the outer circumference surface of the paper adsorption roller.

Description

Image transfer unit and electrophotographic image forming apparatus with the same

1 is a cross-sectional view showing a conventional image transfer unit.

2 is a cross-sectional view showing an electrophotographic image forming apparatus according to a preferred embodiment of the present invention.

3 is a perspective view illustrating the image transfer unit of FIG. 2, and FIG. 4 is an enlarged perspective view of a part of the image transfer unit.

<Description of the symbols for the main parts of the drawings>

100 ... electrophotographic image forming apparatus 110 ...

114 ... Photosensitive media 125 ...

130 ... Fusing unit 140 ... Image transfer unit

141 ... Transfer Belt 150 ... Transfer Roller

152 ... Paper Suction Roller 143 ... First Roller

145 ... Second roller 155 ... Protective member

The present invention relates to an electrophotographic image forming apparatus, and more particularly, to an image transfer unit capable of preventing contamination of paper due to waste toner, and an electrophotographic image forming apparatus having the same.

In general, an electrophotographic image forming apparatus is, for example, a laser printer, a digital copier, etc., to scan light on a photosensitive medium charged to a predetermined potential to form an electrostatic latent image on its outer peripheral surface, and to develop a developer (deeloping agent) on the electrostatic latent image. It is a device that prints an image by inserting the toner and developing it into a visible image, then transferring and fixing the same on paper.

1 is a cross-sectional view showing an example of an image transfer unit for transferring a visible image developed on a photosensitive medium onto a sheet of paper.

Referring to FIG. 1, the conventional image transfer unit 10 includes a first roller 11 and a second roller 12 arranged in parallel in the vertical direction, and the first roller 11 and the second roller 12. It includes a transfer belt 15 wound around the circulation. Transfer rollers 20 are disposed between the first roller 11 and the second roller 12, and interposed between the transfer belt 15 and the developer roller 25 on the opposite side of the transfer roller 20. The photosensitive medium 27 is disposed. In addition, the paper adsorption roller 30 is disposed on the opposite side of the second roller 12 with the transfer roller 15 interposed therebetween. When a predetermined voltage is applied to the paper adsorption roller 30, static electricity is induced to the paper being transported so that the paper is absorbed by the transfer belt 15 and is conveyed upward.

In the conventional image transfer unit 10 having the above configuration, the waste toner spilled from the developing unit 25 in the printing process falls down to contaminate the paper adsorption roller 30 and the transfer belt 15, and thus contaminate. There is a problem that the paper adsorption roller 30 and the transfer belt 15 are contaminated with the paper and degrade the quality of the printed image.

The present invention is to solve the above problems, to provide an image transfer unit having an improved structure so that the contamination of the paper adsorption roller and the transfer belt and an electrophotographic image forming apparatus having the same.

The present invention to solve the above technical problem, the first roller and the second roller arranged in parallel below the first roller;

A transfer belt wound around the first roller and the second roller;

A transfer roller disposed between the first roller and the second roller, the transfer roller being disposed opposite the photosensitive medium with the transfer belt interposed therebetween;

A paper adsorption roller interposed between the transfer belt and disposed opposite the second roller; And,

It is provided with an image transfer unit comprising a; protection member to cover the upper outer peripheral surface of the paper adsorption roller.

Preferably, the protective member may be configured not to cover the lower outer peripheral surface of the paper adsorption roller.

Preferably, the protective member may be configured to be mounted on the shafts of both ends of the paper adsorption roller.

In addition, the present invention provides an electrophotographic image forming system comprising a photosensitive medium on which an image is developed on an outer circumferential surface by supplying toner, and an image transfer unit which absorbs and transfers paper and transfers the image developed on the photosensitive medium to the paper In the apparatus,

The image transfer unit includes: a second roller arranged in parallel under the first roller and the first roller;

A transfer belt wound around the first roller and the second roller;

A transfer roller disposed between the first roller and the second roller, the transfer roller being disposed opposite the photosensitive medium with the transfer belt interposed therebetween;

A paper adsorption roller interposed between the transfer belt and disposed opposite the second roller; And,

It provides a electrophotographic image forming apparatus comprising a; protection member for covering the upper outer peripheral surface of the paper adsorption roller.

Hereinafter, with reference to the accompanying drawings will be described in detail an image transfer unit and an electrophotographic image forming apparatus having the same according to a preferred embodiment of the present invention.

2 is a cross-sectional view illustrating an electrophotographic image forming apparatus according to a preferred embodiment of the present invention, FIG. 3 is a perspective view illustrating the image transfer unit of FIG. 2, and FIG. 4 is an enlarged portion of the image transfer unit. It is a perspective view shown.

Referring to FIG. 2, in the electrophotographic image forming apparatus 100 according to an exemplary embodiment of the present invention, a direct image in which visible images of different colors are sequentially transferred onto a sheet of paper and overlapped to form a color image directly on the sheet of paper. Type color image forming apparatus. The electrophotographic color image forming apparatus 100 includes four developing devices 110Y, 110M, 110C, and 110K, four optical scanners 125Y, 125M, 125C, and 125K, and a transfer belt 141 inside the case 101. It includes an image transfer unit 140, and a fixing unit 130. In addition, a paper feed cassette 127 in which paper is loaded, a pickup roller 128 for picking up sheets of paper from the paper cassette 127, a feed roller 129 for conveying the picked up paper, and a paper on which images are printed. It is provided with a discharge roller 132 to discharge the outside of the case (101).

The developing unit 110 is a cartridge type that is replaced with a new one when the developer toner is consumed. In the embodiment shown in FIG. 2, toners of different colors for printing a color image, for example, yellow (Y), Four developing units 110Y, 110M, 110C, and 110K each containing toners of magenta (M), cyan (C), and black (K) colors are provided.

When the door 102 of one side of the case 101 is opened, the image transfer unit 140 is horizontally arranged in association with the opening of the door 102, so that the toner is used to develop the developer 110Y, 110M, 110C, and 110K. ) Can be exchanged.

In this embodiment, four optical scanners 125Y, 125M, 125C, and 125K are provided in correspondence with the four developing devices 110Y, 110M, 110C, and 110K. Each optical fiber scanner 125Y, 125M, 125C, and 125K emits light corresponding to image information of yellow (Y), magenta (M), cyan (C), and black (K) colors of each developer housing (111Y, 111M, 111C). , 111K) to the photosensitive media 114Y, 114M, 114C, and 114K mounted therein. A laser scanning unit (LSU) using a laser diode as a light source may be employed as the optical scanners 125Y, 125M, 125C, and 125K.

Each of the developing devices 110Y, 110M, 110C, and 110K includes photosensitive media 114Y, 114M, 114C, 114K, and developing rollers 115Y, 115M, 115C, and 115K inside the housings 111Y, 111M, 111C, and 111K. Equipped. In the photosensitive media 114Y, 114M, 114C, and 114K, a portion of an outer circumferential surface facing the transfer belt 141 is exposed to the outside of the housings 111Y, 111M, 111C, and 111K for image transfer. . In addition, the developing devices 110Y, 110M, 110C, and 110K include charging rollers 119Y, 119M, 119C, and 119K, respectively. A charging bias is applied to the charging rollers 119Y, 119M, 119C, and 119K in order to charge the outer periphery of the photosensitive medium 114Y, 114M, 114C, and 114K to a uniform electric potential.

The developing rollers 115Y, 115M, 115C, and 115K attach toner to the outer circumference thereof and supply them to the photosensitive media 114Y, 114M, 114C, and 114K. The developing bias for supplying the toner to the photosensitive media 114Y, 114M, 114C, 114K is applied to the developing rollers 115Y, 115M, 115C, and 115K. In addition, although not shown, inside the housings 111Y, 111M, 111C, and 111K, a supply roller and a development roller 115Y, 115M, 115C, and 115K supplying toner to the developing rollers 115Y, 115M, 115C, and 115K. A doctor blade, which regulates the amount of toner attached, and a stirrer for stirring the toner contained in the housings 111Y, 111M, 111C, and 111K so as not to harden, and transferring the toner to the supply roller side. The developing devices 110Y, 110M, 110C, and 110K of the present embodiment form passages so that the light scanned by the optical scanning machines 125Y, 125M, 125C, and 125K can be scanned onto the photosensitive media 114Y, 114M, 114C, and 114K. Openings 112Y, 112M, 112C, and 112K.

The image transfer unit 140 includes a first roller 143 which is a driving roller, a second roller 145 which is a driven roller arranged in parallel under the first roller 143, and the first roller 143. And four transfer rollers 150Y, 150M, 150C, and 150K disposed between the transfer belt 141 wound around the second roller 145 and disposed between the first roller 143 and the second roller 145. It is provided. In addition, the auxiliary support rollers 147 and 148 for supporting the transfer belt 141 is provided. The four transfer rollers 150Y, 150M, 150C, and 150K are disposed on opposite sides of the four photosensitive media 114Y, 114M, 114M, and 114K with the transfer belt 141 interposed therebetween. A transfer bias is applied to the transfer rollers 150Y, 150M, 150C, and 150K.

In addition, the image transfer unit 140 has a paper adsorption roller 152 disposed on the opposite side of the second roller 145 with the transfer belt 141 interposed therebetween, and an upper side of the paper adsorption roller 152. It is provided with a protective member 155 to cover the outer peripheral surface. The paper adsorption roller 152 induces static electricity to the paper picked up from the paper feed cassette 127 and conveyed upward so that the paper is adsorbed on the transfer belt 141.

Hereinafter, the color image forming process of the electrophotographic color image forming apparatus as described above will be described.

Each photosensitive medium 114Y, 114M, 114C, 114K is charged at a uniform potential by the charging bias applied to the charging rollers 119Y, 119M, 119C, 119K. The four optical scanners 125Y, 125M, 125C, and 125K each emit light corresponding to image information of yellow (Y), magenta (M), cyan (C), and black (K) colors. And 112K through the photosensitive media 114Y, 114M, 114C, and 114K, whereby an electrostatic latent image is formed on the outer circumferential surface of the photosensitive media 114Y, 114M, 114C, and 114K. The developing bias is applied to the developing rollers 115Y, 115M, 115C, and 115K. Then, the toner moves from the developing rollers 115Y, 115M, 115C, and 115K to the outer circumferential surface of the photosensitive media 114Y, 114M, 114C, and 114K. , Visible images of magenta (M), cyan (C) and black (K) colors are developed.

On the other hand, the paper is picked up from the paper feed cassette 127 by the pickup roller 128 and fed by the feed roller 129. When a predetermined voltage is applied to the paper adsorption roller 152, static electricity is induced to the paper fed upwardly, and the paper is attracted to the transfer belt 141 by the electrostatic force, and at the same speed as the traveling line speed of the transfer belt 141. Transferred.

The front end of the sheet to be transferred to the transfer belt 141 has a transfer roller 150Y and a transfer belt 141 at the front end of a visible image of yellow (Y) color formed on the outer circumferential surface of the photosensitive medium 114Y. The transfer nip is reached in accordance with the point of time when the transfer nip is formed to face. At this time, when a transfer bias is applied to the transfer roller 150Y, the visible image formed on the photosensitive medium 114Y is transferred to the paper. As the paper is continuously conveyed, the visible images of magenta (M), cyan (C), and black (K) colors formed on the outer circumferential surfaces of the other photosensitive media 114M, 114C, and 114K are sequentially transferred to the paper, and a color image is printed on the paper. Is formed. The fixing unit 130 applies heat and pressure to the color image formed on the paper to fix it to the paper. The paper on which the fixing is completed is discharged out of the case 101 by the discharge roller 132.

3 to 4, the image transfer unit 140 includes a shaft 143a at the end of the first roller 143, a shaft 145a at the end of the second roller 145, and a paper adsorption roller 152. A side frame 160 rotatably supporting the shaft 152a at the end. At the end of the first roller 143, a drive gear 144 for receiving power from a motor (not shown) is provided.

The protection member 155 extends in the longitudinal direction of the paper adsorption roller 152 to cover the upper outer circumferential surface of the paper adsorption roller 152 and has a circular cross section (see FIG. 2). Thus, even if the waste toner is leaked from the developing devices 110Y, 110M, 110C, and 110K in the printing process, the waste toner falls only on the outside of the protection member 155 or slips down from the protection member 155, and the paper adsorption roller 152 is removed. ), Contamination by waste toner is suppressed. In addition, since waste toner is not attached to the outer circumferential surface of the paper adsorption roller 152, contamination of the transfer belt 141 caused by the transfer of the waste toner from the paper adsorption roller 152 to the transfer belt 141 is also suppressed.

The protection member 155 is opened so as not to cover the lower outer circumferential surface of the paper adsorption roller 152. Thus, even if a small amount of waste toner penetrates through the paper adsorption roller 152 beyond the protection member 155, it can be easily discharged through the open bottom. In addition, it is possible to easily clean the paper adsorption roller 152 without removing the protection member 155 from the paper adsorption roller 152 through the open bottom.

Holders 156 are provided at both ends of the protective member 155 to be mounted on the shafts 152a at both ends of the paper adsorption roller 152. When the opening 156a of the holder 156 is pushed against the shaft 152a and the protection member 155 is pushed against the shaft 152a, the holder 156 is opened to accommodate the shaft 152a. As the holder 156 is retracted by elasticity, the protection member 155 is mounted to the shaft 152a.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

The image transfer unit and the electrophotographic image forming apparatus having the same of the present invention include a protection member for protecting the paper adsorption roller, thereby preventing damage to the paper adsorption roller. In addition, contamination of the paper adsorption roller and the transfer belt due to the outflow of the waste toner is suppressed, thereby preventing the deterioration of the print image quality.

In addition, according to a preferred embodiment of the present invention, it is possible to clean the paper adsorption roller without removing the protective member, it is possible to prevent damage to the transfer belt or paper adsorption roller due to inadvertent mounting.

Claims (4)

A second roller arranged in parallel under the first roller and the first roller; A transfer belt wound around the first roller and the second roller; A transfer roller disposed between the first roller and the second roller, the transfer roller being disposed opposite the photosensitive medium with the transfer belt interposed therebetween; A paper adsorption roller interposed between the transfer belt and disposed opposite the second roller; And, And a protective member surrounding the upper outer circumferential surface of the paper adsorption roller. According to claim 1, The protective member is an image transfer unit, characterized in that configured not to cover the lower outer peripheral surface of the paper adsorption roller. The method according to claim 1 or 2, And the protective member is configured to be mounted on shafts at both ends of the paper adsorption roller. An electrophotographic image forming apparatus comprising: a photosensitive medium on which an image is developed on an outer circumferential surface by supplying toner; and an image transfer unit which absorbs and transfers paper and transfers the image developed on the photosensitive medium to the paper; Image transfer unit, A second roller arranged in parallel under the first roller and the first roller; A transfer belt wound around the first roller and the second roller; A transfer roller disposed between the first roller and the second roller, the transfer roller being disposed opposite the photosensitive medium with the transfer belt interposed therebetween; A paper adsorption roller interposed between the transfer belt and disposed opposite the second roller; And, And a protective member covering the upper outer circumferential surface of the paper suction roller to cover the upper outer circumferential surface of the paper adsorption roller.

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