JP3084909B2 - Photoconductor unit of electrophotographic apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus for forming a color image on a transfer material by superposing a plurality of monochrome toner images.

[0002]

2. Description of the Related Art In recent years, devices using dry toner occupy the mainstream in electrophotographic apparatuses, and have been put to practical use as copiers, laser beam printers (hereinafter, LBP) and the like. In recent years, the demand for colorization has been increasing from the market in addition to monochrome, and color copying machines have been put on the market.

An electrophotographic apparatus that forms a color image by applying an electrophotographic process technology selectively forms an image by irradiating an exposure light beam corresponding to each color onto a photosensitive member having a photosensitive layer.
Developing a plurality of electrostatic latent images corresponding to a specific component among the plurality of predetermined color components with toner of each predetermined color,
A method of forming a color image on one transfer material by superimposing the single-color toner images has been adopted.

For example, US Pat. No. 4,652,115
In Japanese Patent Application Laid-Open No. 63-292156, an intermediate transfer member is provided between a photosensitive member and a transfer material conveying path, and toner images of different colors individually formed on the photosensitive member are optionally transferred to the intermediate transfer member. There has been proposed a method in which a composite image is obtained by transferring the composite image on a body, and the composite image is collectively transferred to one transfer material.

Hereinafter, a conventional electrophotographic apparatus using an intermediate transfer member will be described with reference to FIGS. FIG. 5 is a configuration diagram of an electrophotographic apparatus using an intermediate transfer member, and FIG. 6 is a side view of a conventional photoconductor unit.

In FIGS. 5 and 6, the photosensitive unit 1
Is a photoreceptor 2 in which a photosensitive layer such as selenium (Se) or an organic photoconductor (OPC) is applied in a thin film shape on the outer peripheral surface of a belt base material such as a seamless closed loop resin, and the like. It has a supporting exposure roller 3, a driving roller 4, a tension roller 5, and a charger 6 for charging the photoconductor. The photoconductor 2 has two fixed exposure rollers 3,
A vertical plane 2a is formed between the drive rollers 4, and tension is applied to the photoconductor 2 by a tension roller 5 pressed in the direction of arrow C from the inside of the photoconductor 2, and is driven by a drive motor (not shown). Due to the driving force of the driving roller 4, it is rotated in the direction of arrow A. As shown in FIG. 5, the charger 6, the exposure optical system 7, black (K), yellow (Y), and magenta (M) are arranged on the peripheral surface of the belt-shaped photoconductor 2 in the rotation direction of the photoconductor indicated by an arrow A. ), Cyan (C) color developing units 8K, 8Y, 8M, 8C, an intermediate transfer body unit 9, a photoconductor cleaning device 10, and a static eliminator 11. As shown in FIG. 6, the charger 6 includes a charging wire 12 made of a tungsten wire or the like, and a shield plate 13 and a grid plate 14 made of a metal plate.
By applying a high voltage of about 4 to 5 kv to the charging line 12, the charging line 12 causes a corona discharge and the grid plate 14.
To charge the photoreceptor 2 uniformly. Reference numeral 15 denotes an exposure light beam emitted from the exposure optical system 7. The exposure light 15 is obtained by subjecting an image signal from a gradation conversion device (not shown) to light intensity modulation or pulse width modulation by a laser drive circuit (not shown), and forms a static image corresponding to a specific color on the photoreceptor 2. An electrostatic latent image is formed. Each developing device stores toner corresponding to each color, and a developing sleeve 33 for charging the toner.
Is provided. The development of each color is performed by the separation / contact cams 16K, 16Y, 1 whose both ends are rotatably supported by the body body.
6M and 16C are rotated in accordance with the color selection signal, and the selected developing device, for example, 8K is brought into contact with the photoconductor 2 to perform the operation. The unselected developing units 8Y, 8M, and 8C are separated from the photosensitive member 2. The intermediate transfer body unit 9 includes a seamless loop belt-shaped intermediate transfer body 17 made of a conductive resin or the like, an intermediate transfer body driving roller 18 for driving the intermediate transfer body 17, an intermediate transfer body transfer roller 19, and an intermediate transfer body. A tension roller 20 is provided to apply tension to the intermediate transfer member by pressing in the direction of arrow D from the inside of the transfer member 17, and the driving force of the intermediate transfer member drive roller 18 by a drive motor (not shown) causes the arrow E to move. Orbit in the direction. Further, the intermediate transfer member 17
In order to transfer the toner image on the photoconductor 2 to the photoconductor 2, an intermediate transfer roller 21 is provided to face the photoconductor 2 with the intermediate transfer member 17 interposed therebetween.

Reference numeral 22 denotes an intermediate transfer member reference detecting sensor for detecting a reference position of the intermediate transfer member 17.
The reference position is detected by an intermediate transfer member reference mark such as a slit disposed at one end of the reference mark. Reference numeral 23 denotes an intermediate transfer member cleaning device for scraping residual toner on the intermediate transfer member 17, which is separated from the intermediate transfer member 17 while forming a composite image of each color on the intermediate transfer member 17, It contacts the intermediate transfer member only when cleaning is performed. Reference numeral 24 denotes a transfer material cassette containing a transfer material (paper) 25. The transfer material 25 is sent out one by one from a transfer material cassette 24 to a paper transport path 27 by a paper feed roller 26. Reference numeral 28 denotes a registration roller for temporarily stopping the transfer material 25 to make the transfer material 25 coincide with the position of the composite image on the intermediate transfer body 17, and is in pressure contact with a driven roller 29. 30
Reference numeral denotes a transfer roller for transferring the composite image on the intermediate transfer member 17 to the transfer material 25. The transfer roller contacts and rotates with the intermediate transfer member 17 only during transfer. 31 is a heat roller 3 having a heat source inside.
2 and a pressure roller 33.
The composite image transferred onto the transfer roller 5 is fixed to the transfer material 25 by pressure and heat with the rotation of the heat roller 32 and the pressure roller 33 to form a color image.

The relationship between the components and the operation of the electrophotographic apparatus including the above components will be described below.

The photosensitive member 2 and the intermediate transfer member 17 are driven by drive sources (not shown), and are controlled so that their peripheral speeds become the same constant speed. Further, the intermediate transfer body 1
An image forming area 7 is previously set by an intermediate transfer member reference detection sensor 22 that detects an intermediate transfer member reference mark for determining a reference position.

In this state, first, a high voltage of about -4 kV to -5 kV is applied to the charging line 12 in the charger 6 connected to the high voltage power supply to cause a corona discharge to be performed, thereby making the surface of the photosensitive member 2 uniform. Charge to about 700V. Next, the photoreceptor 2 is rotated in the direction of arrow A, and the uniformly charged surface of the photoreceptor 2 is irradiated with an exposure light beam 15 of a laser beam corresponding to, for example, a predetermined black (K) in a plurality of color components. Then, an irradiated portion on the photoreceptor 2 forms an electrostatic latent image from which electric charges have disappeared. The timing of starting the latent image formation at this time is determined by a signal from the intermediate transfer body reference detection sensor 22 that detects the reference position of the intermediate transfer body 17. On the other hand, the black developing device 8K detects the reference position with the intermediate transfer member reference detecting sensor 22, and after a predetermined time elapses, is pushed in the direction of arrow B by the rotation of the separation / contact cam 16K and contacts the photosensitive member 2. On the other hand, the developing sleeve 34K having the toner on the surface immediately before the contact
To a negative potential of about -300V. If a negative charge is given to the toner in advance, the toner adheres only to a portion of the photoreceptor 2 where the exposure light beam 15 has been irradiated and the charge has disappeared, and development is performed by a so-called negative-positive process. The developing device 8K that has completed the development moves from the contact position with the photoconductor 2 to the separation position by rotating the separation / contact cam 16K by 180 degrees.
The toner image formed on the photosensitive member 2 by the developing device 8K is transferred to the intermediate transfer member 17 by applying a high voltage of +800 V to the intermediate transfer roller 21 arranged in contact with the photosensitive member 2 for each color. The residual toner that has not been transferred from the photoconductor 2 to the intermediate transfer body 17 is removed by a cleaning blade 10 a housed in the photoconductor cleaning device 10, and the charge on the photoconductor 2 is further removed by the charge eliminator 11.

Next, when the color of cyan (C) is selected, the separation / contact cam 16C rotates, and this time, the developing unit 8C is pushed in the direction of the photosensitive member 1 to come into contact with the photosensitive member 1 to develop the cyan (C). To start. In the case of a copying machine or a printer using four colors, the above-described developing operation is sequentially repeated four times, and the intermediate transfer member 17 is formed.
The four color black (B), cyan (C), magenta (M), and yellow (Y) toner images are superimposed on each other to form a composite image. The transfer material 25 is sent from the transfer material cassette 24 along the paper transport path 27, and is stopped by a registration roller 28 which takes timing to transfer the composite image. The composite image formed on the intermediate transfer body is contacted with the intermediate transfer body 17 by the paper transfer roller 30 which has been separated so far, and
A high voltage of about 1000 V is applied, and the toner image is collectively transferred to the transfer material 25 conveyed from the registration roller 28 by pressure. The residual toner on the intermediate transfer body 17 that has not been completely transferred onto the transfer material 25 by the paper transfer roller 30 is removed by the intermediate transfer body cleaning device 23. Subsequently, the transfer material 25 onto which the toner image has been transferred is supplied to the fixing device 3.
1, where it is fixed by the heat of the heat roller 32 and the nip pressure of the pressure roller 33 and is output as a color image. The intermediate transfer member cleaning device 23 is separated from the intermediate transfer member 17 until a combined image is obtained, and is brought into a contact state after being transferred to the transfer material 25 by the paper transfer roller 30 to remove residual toner. You.

With the above operation, recording of one image is completed, and a high quality color recorded image is obtained. Here, FIG.
The conventional photoconductor unit 1 will be described with reference to FIG.

In FIG. 6, a shaft 5a of the tension roller 5 is shown.
Is guided by an elongated hole 1b provided on the side wall 1a, and is pressed in the direction of arrow C by a spring 35. Since the respective axes of the drive roller 4 and the exposure roller 3 of the photoconductor 2 are fixed on the side wall 1a, the photoconductor 2 is tensioned by the pressing force of the tension roller 5 in the direction of arrow C. When the drive roller 4 rotates, the photosensitive member 2 rotates in the direction of arrow A. Here, the circumferential length difference of the photoconductor 2 is almost impossible to produce the same circumferential length in manufacturing, so that the circumferential length difference always occurs for each product. For this reason, when the photoconductor is replaced, if the circumference of the new photoconductor 2 is longer than the circumference of the previous photoconductor 2, the position of the tension roller 5 moves to the position of 5b indicated by a two-dot chain line and the photoconductor 2 is moved. Tension. Further, since the photoconductor cleaning device 10 is fixed to the side wall 1a to which the photoconductor is fixed, the cleaning blade 10 housed in the photoconductor cleaning device 10 is used.
The contact state a changes to a position 10b indicated by a two-dot chain line.

[0014]

As described above, in the structure of the conventional photoreceptor unit 1, the position of the tension roller for applying tension to the photoreceptor fluctuates due to the difference in the circumference of the photoreceptor. Since the contact state with the cleaning blade fluctuates, the pressing force and the contact angle of the cleaning blade on the photoreceptor fluctuate. As a result, defective cleaning of the residual toner on the photoreceptor and turning of the cleaning blade have occurred, resulting in image deterioration of an output image.

The present invention solves the above-mentioned conventional problems, stabilizes the contact of the cleaning blade with the photosensitive member,
An object of the present invention is to provide an electrophotographic apparatus that can always create a high-quality image.

[0016]

In order to achieve the above object, a photoconductor unit of an electrophotographic apparatus according to the present invention comprises an endless belt-shaped photoconductor suspended between two parallel rollers, and an endless belt-shaped photoconductor. A tension roller that applies tension to the photoconductor, a charger that charges the surface of the photoconductor, and a cleaning device that removes residual toner on the surface of the photoconductor at a position where the photoconductor contacts the tension roller. The two parallel rollers and the tension roller are supported by a first housing, and the charger and the cleaning device are mounted on a second housing.
Supported by a housing, the second housing is coupled to the first housing by an axis of one of the two parallel rollers, and an axis of the tension roller is provided on the first housing. The first elongated hole and the second elongated hole provided on the second housing guide the first elongated hole so that the longitudinal direction of the first elongated hole and the longitudinal direction of the second elongated hole intersect at a substantially right angle. It is.

[0017]

According to the present invention, the surface of the photoreceptor can be pressed with a constant pressing force and a constant contact angle by the above-mentioned structure, so that it is possible to prevent defective cleaning of residual toner and image deterioration due to turning of the cleaning blade.

[0018]

Next, an embodiment of the present invention will be described with reference to the drawings.

The overall configuration of the electrophotographic apparatus according to one embodiment of the present invention is the same as that of the prior art shown in FIG.

FIG. 1 is a side view of a photosensitive unit 1 according to an embodiment of the present invention. The photoconductor unit 1 is roughly composed of two housings. One is a second housing 1c in which the charger 6 and the photoconductor cleaning device 10 are incorporated, and the other is the exposure roller 3 and the driving roller 4
Is a first housing 1d in which the shaft of FIG. The shaft 5a of the tension roller 5 receives the pressing force of the spring 35 as in the conventional example, but the tension roller shaft 5a is guided by the elongated hole 1e on the first housing 1d and the second housing It is also guided by a slot 1f above 1c. Slot 1e
Is the pressing direction of the spring 35 as in the conventional example, but the longitudinal direction of the elongated hole 1f intersects at right angles to the longitudinal direction of the elongated hole 1e, and the tension roller shaft 5a
And a shaft 3 a of the exposure roller 3.

FIGS. 2 (a) and 2 (b) show a state where the position of the tension roller 5 moves as the circumference of the photosensitive member 2 changes. FIG. 2B shows a state in which the circumferential length of the photoconductor 2 is longer than that in FIG. 2A, but the tension roller shaft 5a is moved in the direction of arrow C by the pressing force of the spring. At this time, the second housing 1c can rotate around the exposure roller shaft 3a. Therefore, the contact state between the cleaning blade 10a and the tension roller 3 can be kept the same as in FIG. 2A.
Therefore, even if the circumference of the photoconductor 2 changes, cleaning failure of the residual toner on the photoconductor 2 does not occur.

FIG. 3 is a side view of a photosensitive unit 1 according to another embodiment of the present invention. The photoreceptor unit 1 is the same as FIG. 1 in that it is composed of two housings. That is, one is the charger 6 and the photoconductor cleaning device 10
Is a second housing 1c in which the shafts of the exposure roller 3 and the driving roller 4 are installed.
It is. The shaft 5a of the tension roller 5 receives the pressing force of the spring 35 as in the conventional example, but the tension roller shaft 5a is guided by the long hole 1e on the first housing 1d.
Unlike FIG. 1, the elongated hole 1f on the second housing 1c is fitted with the shaft 3a of the exposure roller 3. The longitudinal direction of the long hole 1e is the pressing direction of the spring 35 as in the conventional example,
The longitudinal direction of the long hole 1f intersects at right angles to the longitudinal direction of the long hole 1e, and is provided in parallel with a line connecting the tension roller shaft 5a and the shaft 3a of the exposure roller 3.

FIGS. 4A and 4B show a state in which the circumference of the photosensitive member 2 changes and the position of the tension roller 5 moves. FIG. 4B shows a state in which the circumferential length of the photoconductor 2 is longer than that in FIG. 4A, but the tension roller shaft 5a is moved in the direction of arrow C by the pressing force of the spring. At this time, the second housing 1c can rotate around the exposure roller shaft 3a. Therefore, the contact state between the cleaning blade 10a and the tension roller 3 can be kept the same as in FIG. 4A.
Therefore, even if the circumference of the photoconductor 2 changes, cleaning failure of the residual toner on the photoconductor 2 does not occur.

[0024]

As is apparent from the above embodiments, according to the present invention, the charger for charging the photosensitive member separately from the first housing supporting the roller for rotating the endless belt-shaped photosensitive member. And a second housing to which a cleaning device for cleaning is fixed.
Since the housing rotates relative to the first housing, the contact condition between the cleaning blade of the cleaning device and the photoconductor does not change. Therefore, even when the photoconductor is replaced, the cleaning blade remains on the photoconductor. Since the surface is pressed at a constant pressure and a constant contact angle, it is possible to prevent poor cleaning of residual toner and image deterioration due to turning of the cleaning blade.

[Brief description of the drawings]

FIG. 1 is a side view of a photoconductor unit of an electrophotographic apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a photosensitive unit of the electrophotographic apparatus according to one embodiment of the present invention.

FIG. 3 is a side view of a photoconductor unit of an electrophotographic apparatus according to another embodiment of the present invention.

FIG. 4 is a cross-sectional view of a photoconductor unit of an electrophotographic apparatus according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view of an electrophotographic apparatus using a photosensitive unit according to an embodiment of the present invention and a photosensitive unit according to a conventional example.

FIG. 6 is a cross-sectional view of a photosensitive unit of a conventional electrophotographic apparatus.

[Explanation of symbols]

 Reference Signs List 1 photoconductor unit 1e first long hole 1f second long hole 2 endless belt-shaped photoconductor 3 exposure roller 4 drive roller 5 tension roller 6 charger 10 cleaning device 35 spring

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 15/00 550 G03G 21/00 350-352 G03G 21/16-21/18

Claims (3)

(57) [Claims] An endless belt-shaped photoconductor suspended between two parallel rollers; a tension roller for applying tension to the endless belt-shaped photoconductor; a charger for charging a surface of the photoconductor; A cleaning device that removes residual toner on the surface of the photoconductor at a position where the photoconductor contacts the tension roller, wherein the two parallel rollers and the tension roller are supported by a first housing; And the cleaning device are supported by a second housing, and the second housing is connected to the first housing by the axis of one of the two parallel rollers, and the axis of the tension roller is connected to the first housing by the first housing. Guided by a first elongated hole provided on the housing and a second elongated hole provided on the second housing, the longitudinal direction of the first elongated hole and the longitudinal direction of the second elongated hole intersect substantially at right angles. Photoconductor unit of an electrophotographic apparatus configured as described above. 2. An endless belt-shaped photoconductor suspended between two parallel rollers, a tension roller for applying tension to the endless belt-shaped photoconductor, a charger for charging a surface of the photoconductor, A cleaning device that removes residual toner on the surface of the photoconductor at a position where the photoconductor contacts the tension roller, wherein the two parallel rollers and the tension roller are supported by a first housing; And the cleaning device are supported by a second housing, the second housing is coupled to the first housing by an axis of one of the two parallel rollers, and an axis of the tension roller is Guided by a first elongated hole provided on one housing and a second elongated hole provided on the second housing, the longitudinal direction of the first elongated hole and the longitudinal direction of the second elongated hole are substantially perpendicular to each other. Intersect and the axis of the tension roller is When a tension is applied to the photoreceptor by pressing in the direction of the cleaning blade of the cleaning device by a spring force along the one elongated hole, the axis of the tension roller can move along the second elongated hole. Second
A photoconductor unit of an electrophotographic apparatus, wherein a housing rotates around an axis of a roller coupled to the first housing to reduce a change in a relative position between the cleaning blade and the tension roller. 3. A parallel roller having a bearing fixed on a first housing, a tension roller having a bearing slidably fitted in a first elongated hole provided on the first housing, and An endless belt-shaped photoconductor suspended between the parallel rollers and the tension roller; a charger fixed on the second housing and charged on the surface of the photoconductor; and a tensioner fixed on the second housing. A cleaning device for removing residual toner by a cleaning blade in contact with the photoconductor at a tangent plane of a cylindrical surface formed by a roller pressing the photoconductor, and a fixed bearing provided on the second housing and the first bearing; The bearing sliding in the first elongated hole on the housing shares the tension roller shaft to connect the first housing and the second housing, and the second housing is connected to the second housing.
A second elongated hole substantially perpendicular to the longitudinal direction of the first elongated hole is provided in the housing to make one roller shaft of the two parallel rollers slide with each other. The shaft of the parallel roller can move along the second elongated hole when the tension is applied to the photoconductor by pressing the photosensitive member in the direction of the cleaning blade by the spring force along the elongated hole. The photosensitive body unit of the electrophotographic apparatus, wherein the two housings rotate around an axis of a tension roller coupled with the first housing to reduce a change in a relative position between the cleaning blade and the tension roller.