JP2002116660A - Photosensitive body and image forming device utilizing it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely gain continuity between a substrate of a photosensitive body and a supporting shaft and to prevent the generation of electrical trouble such as insulation failure with a simple constitution. SOLUTION: In the device, a stable continuity is gained between the substrate 21 and the supporting shaft 26 without generating any local tearing or falling off as in a conductive brush when used over a long period of time by gaining continuity between the substrate 21 of the photosensitive body 2 and the supporting shaft 26 by a conductive member 24 consisting of an assembly of short fibers with conductivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoreceptor used for electrophotographic image formation and an image forming apparatus using the same, and more particularly, to a photoreceptor substrate having a photosensitive layer formed on the surface of a cylindrical conductive substrate. The present invention relates to stabilization of conduction with a support shaft.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine using an electrophotographic system, a photosensitive layer surface is uniformly charged in order to form an electrostatic latent image on the surface of a photoreceptor, and then exposed to light. In order to release the surface charge, the cylindrical base of the photoreceptor and the support shaft holding the base are electrically connected to ground. In order to electrically connect the base of the photoreceptor and the support shaft, for example, as shown in Japanese Patent Application Laid-Open No. 9-114168, a stainless steel flange is press-fitted into a cylindrical conductive base of the photoreceptor. A conductive brush having a brush formed by cutting a thread-like long fiber such as carbon or carbon into a predetermined length is attached, one end of the conductive brush is brought into contact with the inner surface of the base, and the other end is The support shaft is slidably contacted, and the base of the photoconductor and the support shaft are electrically connected by a conductive brush.

[0003]

However, if a conductive brush made of a thin wire such as stainless steel or carbon is slid on the support shaft for a long time, a part of the brush may fall off or break, and the brush may be disconnected from the support shaft. There was a possibility that the contact pressure was reduced to cause conduction failure. Further, there is a risk that the long fibers that have fallen off may adhere to energized locations in the image forming apparatus and cause electrical troubles such as insulation failure.

The present invention solves the above-mentioned disadvantages, ensures conduction between the base of the photoreceptor and the support shaft with a simple structure, prevents the brush from coming off, and prevents electrical trouble such as insulation failure. It is another object of the present invention to provide a photoreceptor capable of forming a stable image for a long period of time and an image forming apparatus using the same.

[0005]

A photoreceptor according to the present invention has a cylindrical conductive substrate having a photosensitive layer formed on a surface thereof, and an insulating flange press-fitted into an end of the substrate.
In a photoreceptor that rotates around a metal support shaft attached to the center of a flange, the base and the support shaft are electrically connected by a conductive member that is an aggregate of conductive short fibers.

[0006] It is desirable that the thickness of the aggregate of short fibers constituting the conductive member be 0.5 mm to 4.0 mm. Also,
The diameter of the single filament of the short fiber constituting the conductive member is 0.00
It is good to set it to 3 mm to 0.1 mm.

Further, it is preferable to attach a plate-shaped pressing member to the surface of the conductive member opposite to the surface in contact with the support shaft.

Further, it is preferable that a through portion of the support shaft of the conductive member is formed by a slit or a through hole having a diameter smaller than the diameter of the support shaft.

Further, it is desirable that the aggregate of short fibers constituting the conductive member is solidified in a felt shape.

It is preferable that polyethylene terephthalate (PET) fibers be used as the short fibers constituting the conductive member.

[0011] An image forming apparatus according to the present invention is characterized in that an image is formed using the photoreceptor.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A photoreceptor of the present invention has a cylindrical conductive substrate having a photosensitive layer formed on the surface with a uniform film thickness, and a shaft hole press-fitted at both ends of the substrate and having a central hole. It has a resin flange, a conductive member, an earth plate, and a support shaft, and rotates around a support shaft inserted into a shaft hole of the flange to form an image. The conductive member is formed in a rectangular shape by an aggregate of short fibers of, for example, polyethylene terephthalate (PET). The ground plate is formed of a conductive metal material such as aluminum, for example, has a guide hole larger than the shaft hole of the flange at the center, and has a plurality of contact pieces in contact with the inner surface of the base at the outer periphery. The support shaft is formed of a conductive metal. Then, the conductive member is sandwiched and fixed to the end face of the flange on the side to be pressed into the base by a ground plate, and the flange to which the conductive member and the ground plate are fixed is pressed into both ends of the base. When this flange is pressed into both ends of the base, the contact pieces of the ground plate come into contact with the inner surface of the base to electrically connect the base and the conductive member. In this state, when the support shaft is fitted and fixed in the shaft hole of the flange, the tip of the conductive member attached to the flange is bent and comes into contact with the surface of the support shaft, thereby conducting between the base and the support shaft. Connect the substrate to ground.

[0013]

FIG. 1 is a block diagram of one embodiment of the present invention.
As shown in the figure, a printer unit 1 for performing image forming / transfer operations of an image forming apparatus includes a photoconductor 2, a revolver unit 3, a transfer unit 4, a writing unit 5, a paper feed unit 6, a transfer paper transport path 7, and a fixing unit. It has a unit 8. Around the photosensitive member 2, there are provided a discharge lamp 9, a charging charger 10, a revolver unit 3, a transfer unit 4, and a drum cleaning sleeve 11 along the rotation direction of the photosensitive member 2. The revolver unit 3 includes developing units 31, 32, 33, of black (Bk), cyan (C), magenta (M), and yellow (Y).
34. The transfer unit 4 is wound around a plurality of rollers, and has an intermediate transfer belt 41 having a belt mark 42, a primary transfer roller 43, an alignment sensor 44 for reading the belt mark 42, a secondary transfer roller 45, and a belt cleaning. It has a part 46. The intermediate transfer belt 41 has a peripheral length of two sheets of a reference image size, for example, A4 size, so that two rotations of the photoconductor 2 can form two screen images of the same color on the intermediate transfer belt 41. I have.

In this image forming apparatus, when an image forming cycle of an image sent from a host device or a document read by a document reading unit starts, if the image to be formed is one color, the belt of the intermediate transfer belt 41 of the transfer unit 4 is used. Since it is not necessary to detect the mark 42, the toner image formed on the photoconductor 2 is primarily transferred onto the intermediate transfer belt 41 regardless of the position of the belt mark 42. The secondary transfer roller 45 secondary-transfers the toner image onto transfer paper sequentially fed according to the leading end of the toner image transferred onto the intermediate transfer belt 41, and transfers the toner image transferred onto the transfer paper by the fixing unit 8. Settle and discharge. The toner remaining on the intermediate transfer belt 41 is collected by the cleaning unit 46.

If the image to be formed is of two or more colors, the image forming process is started and the belt mark 4 on the intermediate transfer belt 41 is started.
The first color image is formed on the photoconductor 2 based on the detection of the position 2 by the alignment sensor 44, and the formed image is primarily transferred to the intermediate transfer belt 41. The image formation on the photoreceptor 2 and the primary transfer on the intermediate transfer belt 41 are repeated for each color based on the detection of the belt mark 42, and a predetermined color image is superimposed on the intermediate transfer belt 41 to form on the intermediate transfer belt 41. The transferred color image is secondarily transferred to transfer paper.

For example, when a full-color image of A4 size is formed, the first black (Bk) image is formed on the photosensitive member 2 based on the detection of the belt mark 42 provided on the intermediate transfer belt 41. The formed first black (Bk) image is transferred to the intermediate transfer belt 41. Subsequently, a second black (Bk) image is formed on the photoreceptor 2, and the formed second black (Bk) image is transferred to the intermediate transfer belt 41 to be transferred to the intermediate transfer belt 41.
, Two images are simultaneously formed. Thereafter, the first and second cyan (C), magenta (M), and yellow (Y) images are sequentially formed on the photoconductor 2 based on the detection of the belt mark 42 and are superimposed on the intermediate transfer belt 41. In addition, the first and second full-color images are formed on the intermediate transfer belt 41. The image formed on the intermediate transfer belt 41 is secondarily transferred to transfer paper sequentially fed from the paper feed unit 6, fixed by the fixing unit 8, and discharged.

As shown in the sectional view of FIG. 2, the photosensitive member 2 of this image forming apparatus has a cylindrical conductive base 21 having a photosensitive layer formed on the surface thereof with a uniform thickness, and both ends of the base 21. , A resin flange 23 having a shaft hole 22 in the center, a conductive member 24, a ground plate 25, and a support shaft 26.
And a support shaft 26 inserted into the shaft hole 22 of the flange 23
To form an image. A fixed shaft 27 for fixing the conductive member 24 and the ground plate 25 is provided at the tip of the portion of the flange 23 that is press-fitted into the base 21. Conductive member 24
As shown in the front view of FIG. 2, is formed of an aggregate of short fibers of, for example, polyethylene terephthalate (PET), and is formed to have a thickness of 0.5 mm to 4.0 mm. The short fibers forming the conductive member 24 have a diameter of, for example, 0.003 mm.
It is formed of a single filament of about 0.1 mm. The ground plate 25 is formed of a conductive metal material such as aluminum, for example. As shown in the front view in FIG. 4A and the side view in FIG. It has a guide hole 28, and has a plurality of contact pieces 29 on the outer periphery that come into contact with the inner surface of the base 21. The support shaft 26 is formed of a metal having conductivity, for example, a special steel such as nickel chrome steel or chromium molybdenum steel. Then, using the fixed shaft 27 of the flange 23, the conductive member 24 is sandwiched by the ground plate 25 and fixed to the flange 23, and the conductive member 2
The flange 23 to which the 4 and the earth plate 25 are fixed is pressed into both ends of the base 21. When the flanges 23 are pressed into both ends of the base 21, the contact pieces 29 of the ground plate 25 come into contact with the inner surface of the base 21 and the base 21 and the conductive member 2 as shown in FIG.
4 is electrically conducted. When the support shaft 26 is fitted and fixed in the shaft hole 22 of the flange 23 in this state, the tip of the conductive member 24 attached to the flange 23 bends and comes into contact with the surface of the support shaft 26 as shown in FIG. Then, the base 21 and the support shaft 26 are electrically connected to connect the base 21 to the ground.

When the tip of the conductive member 24 attached to the flange 23 is brought into contact with the support shaft 26, the conductive member 24 is tough, has excellent heat resistance, has little creep and fatigue, and has excellent electrical characteristics. Since it is formed of PET fiber, it can be contacted with a sufficient contact pressure. Further, by forming the thickness of the conductive member 24 to 0.5 mm to 4.0 mm, the electrical resistance of the conductive member 24 can be reduced, and the contact area with the support shaft 26 can be sufficiently ensured. Conduction with the shaft 26 can be stably performed. Furthermore, since the conductive member 24 is formed of, for example, an aggregate of short fibers made of PET fibers, it is possible to reduce the occurrence of local cuts or falling off as in the case of using long fibers even when used for a long time. Therefore, stable conduction between the base 21 and the support shaft 26 can be achieved. Also, even if the short fibers forming the conductive member 24 fall off, the conductive member 24 is formed of, for example, a single filament short fiber having a diameter of 0.003 mm to 0.1 mm. It is possible to prevent an electrical trouble such as a short circuit or insulation failure from occurring.

In the above embodiment, the conductive member 24 is connected to the flange 23.
Is fixed to the flange 23 using one fixed shaft 27,
Although the case where the tip of the conductive member 24 is brought into contact with the support shaft 26 has been described, as shown in FIG. 5, a conductive member 24a having a length sufficient to be fixed to the two fixed shafts 27 of the flange 23 is used. Then, a slit 241 may be provided at the center through which the support shaft 26 passes as shown in (a), or a through hole 242 smaller by a certain dimension than the diameter of the support shaft 26 may be provided as shown in (b). . Thus, the slit 241 for passing the support shaft 26 is provided in the conductive member 24a,
By providing the through hole 242 smaller by a certain dimension than the diameter of 6, the contact area between the conductive member 24a and the support shaft 26 can be increased, and the contact pressure of the conductive member 24a on the support shaft 26 can be increased. The contact resistance between the conductive member 24a and the support shaft 26 can be further reduced.

The fitting allowance of the slit 241 for passing the support shaft 26 to the support shaft 26 is set to 0.1 mm to 2.0 mm, and the fitting allowance of the through hole 242 for passing the support shaft 26 to the support shaft 26 is set to 0.2 mm to 4.0 mm. mm
The force of removing the support shaft 26 from the conductive member 24a can be increased, and the contact pressure of the conductive member 24a against the support shaft 26 can be reliably increased. For example, if the diameter
The results of examining the removal force of the support shaft 26 with respect to the conductive member 24a having the through hole 242 having a diameter of 2.0 mm using the 4.0 mm support shaft 26 are shown in the following table.

[0021]

[Table 1]

As shown in the above table, the removal force of the support shaft 26 from the conductive member 24a is changed from 0.85 (N) to 2.92 (N), and the contact force of the conductive member 24a to the support shaft 26 can be reliably increased. Was.

In each of the above embodiments, the case where the conductive members 24 and 24a made of a short fiber aggregate are used has been described. However, as shown in FIG. 6, the conductive member 24 is on the side opposite to the contact surface with the support shaft 26. The pressing member 243 made of a PET film or a metal, non-metal or other resin sheet having a thin thickness of, for example, 50 μm to 200 μm is attached to the surface of the support member 26 by the elastic force of the pressing member 243. The contact force can be increased.

Further, by solidifying the aggregate of short fibers constituting the conductive members 24 and 24a in a felt shape, the contact force of the conductive member 24 with the support shaft 26 can be further increased, and the conductive member 24 can be used for a long time. Also, the short fibers can be prevented from falling off, and the occurrence of electrical trouble due to the falling off of the conductive fibers can be prevented.

As described above, an electrostatic latent image is formed by using the photosensitive member 2 in which conduction is provided between the base 21 and the support shaft 26 by using the conductive members 24 and 24a formed of the aggregate of short fibers. Thus, a stable latent image without pixel omission can be formed, and a high-quality image can be stably formed.

[0026]

As described above, according to the present invention, the base of the photoreceptor and the support shaft are electrically connected to each other by the conductive member made of an aggregate of short fibers having conductivity. Unlike the conductive brush, there is no local break or dropout, and stable conduction between the base and the support shaft can be achieved.

Further, by setting the thickness of the aggregate of the short fibers constituting the conductive member to 0.5 mm to 4.0 mm, the electric resistance of the conductive member is reduced and the contact area with the support shaft is sufficiently ensured. It is possible to stably conduct between the base and the support shaft.

Further, by setting the diameter of the single filament of the short fiber constituting the conductive member to 0.003 mm to 0.1 mm,
Even if the short fiber comes off, it is possible to prevent short-circuiting of a current-carrying part in the image forming apparatus or occurrence of electrical trouble such as insulation failure.

Further, by attaching a plate-like pressing member to the surface of the conductive member opposite to the surface in contact with the support shaft, the contact force of the conductive member to the support shaft can be further increased.

Further, the contact area between the conductive member and the support shaft can be increased by forming the through portion of the support shaft of the conductive member with a slit or a through hole having a diameter smaller than the diameter of the support shaft. In addition, the contact pressure between the conductive member and the support shaft can be increased, and the contact resistance between the conductive member and the support shaft can be further reduced.

Further, by using polyethylene terephthalate (PET) fiber having excellent heat resistance, low creep and fatigue, and excellent electrical properties for the short fibers constituting the conductive member, the conductive member can be used for a long time. And the support shaft can be stably conducted.

Further, by hardening the aggregate of the short fibers constituting the conductive member into a felt shape, it is possible to reliably prevent the short fibers from falling off.

Further, by using the photosensitive member having a conductive path between the base and the support shaft in an image forming apparatus such as a copying machine or a printer, a high quality image without pixel omission can be formed stably. .

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view illustrating a configuration of a photoconductor.

FIG. 3 is a front view illustrating a configuration of a conductive member.

FIG. 4 is a configuration diagram of a flange to which a conductive member and a ground plate are attached.

FIG. 5 is a front view showing the configuration of the second embodiment.

FIG. 6 is a perspective view showing a configuration of a third embodiment.

[Explanation of symbols]

1; printer unit, 2; photoconductor, 3; revolver unit,
4, a transfer unit, 5; a writing unit, 6; a paper supply unit, 8; a fixing unit, 21;
24; a conductive member; 25; a ground plate; 26;

Claims (9)

[Claims] 1. A cylindrical conductive base having a photosensitive layer formed on a surface thereof, and an insulating flange press-fitted into an end of the base. A photoreceptor, characterized in that the base and the support shaft are electrically connected by a conductive member comprising an aggregate of short fibers having conductivity. 2. The photoconductor according to claim 1, wherein the thickness of the aggregate of short fibers constituting said conductive member is 0.5 mm to 4.0 mm. 3. The photoconductor according to claim 1, wherein a diameter of a single filament of the short fiber constituting the conductive member is 0.003 mm to 0.1 mm. 4. The photoconductor according to claim 1, wherein a plate-shaped pressing member is attached to a surface of the conductive member opposite to a surface contacting the support shaft. 5. The photoconductor according to claim 1, wherein a through portion of the support shaft of the conductive member is formed by a slit. 6. The photoconductor according to claim 1, wherein the penetrating portion of the support shaft of the conductive member is formed with a through hole having a diameter smaller than the diameter of the support shaft. 7. The photoconductor according to claim 1, wherein the short fibers constituting the conductive member are polyethylene terephthalate (PET) fibers. 8. The photoconductor according to claim 1, wherein an aggregate of short fibers constituting said conductive member is solidified in a felt shape. 9. An image forming apparatus comprising the photoreceptor according to claim 1.