JPH07323491A - Conductive roll for electrophotographic apparatus - Google Patents

Abstract

PURPOSE:To stabilize the slide contact of the substrates of both of a small diameter photosensitive drum and a small diameter developing roll with the fixed shafts being the centers of rotation of them. CONSTITUTION:In a conductive cylindrical body, the continuity of a spring member 6 and a fixed shaft 2 is taken through the slide plate 7 provided vertically with respect to the fixed shaft 2. Therefore, even when a small diameter cylinder 1 is used, the foot of the spring member 6 can be made long. Therefore, the contact with a slide surface is stabilized and the image flaw or unnecessary radiation noise caused by the instability of the contact resistance of a slide contact part can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus used in an image forming apparatus such as a copying machine, a facsimile, and a laser beam printer for forming an image by an electrophotographic method. More specifically, the present invention relates to an electrical connection structure between a conductive cylindrical substrate and a conductive fixed shaft that is a rotation center axis of the cylinder.

[0002]

2. Description of the Related Art An electrophotographic recording method is composed of a plurality of process means such as a charger, a developing device, a transfer charger, a cleaning section, a photo-electrifier, etc. centering on a photoconductor, and a thermal recording method, an ink jet method. As compared with the recording method, the dot impact recording method, etc., there is a drawback that the recording process means is complicated. The so-called process cartridge system in which a plurality of electrophotographic process means are integrally incorporated and can be attached to and detached from the image forming apparatus main body is easy to maintain and does not make the user feel the complexity of the process. In particular, an integrated process cartridge that integrally incorporates the photoconductor, charger, developer, toner container, and cleaning unit is considered to have reached the end of its life when the toner in the process cartridge is used up, and a new process cartridge must be replaced. To be done. This type of process cartridge is suitable for personal type printers and copying machines in which the number of printed sheets is not so large.

The main process means for electrophotography such as a photoconductor, a charger and a developing device in the process cartridge are electrically imaged by connecting the contact means provided on the main body of the image forming apparatus and the contact means on the process cartridge side. It is connected to the forming apparatus body. Since there is a sliding part in the connection between the rotating body of the photosensitive drum and the base of the developing roll and the fixed shaft that is the center of rotation, there is a need for downsizing, such as in process cartridges. Prior art improvements are needed.

A conventional method for electrically connecting the photosensitive drum in the process cartridge and the main body of the image forming apparatus and grounding the photosensitive drum will be described with reference to FIG.

A flange 103 made by plastic molding is fitted to the end of the photosensitive drum 101 having the photosensitive layer 102 on the surface. Bearing part 1 of flange 103
A conductive fixed shaft 105 passes through 04. A spring member 106 is an elastic member that electrically connects the fixed shaft 105 to the photosensitive drum 101. Spring member 106
The two projections are fixed to the flange 103 by suitable means. One end of the spring member 106 is folded small to form the claws 107 and 108. The elasticity of the claws 107 and 108 electrically connects the spring member 106 and the photoconductor drum 101. Spring member 1
The other end of 06 is largely bent to form a sliding portion 109. Due to the elasticity of the sliding portion 109, the spring member 10
6 and the fixed shaft 105 are slidably connected. Fixed shaft 10
The tip of 5 is connected to the main body via an elastic contact member 110 on the image forming apparatus side. In this way, the photosensitive drum 101 is grounded. Although the above-mentioned conventional example has been described by taking the example of the photosensitive drum, the electric connection between the developing sleeve of the developing device and the shaft of the developing device was also made in the same configuration.

[0006] In the connection structure of the above-mentioned structure, the problem in dealing with miniaturization is that the fixed shaft 105 and the spring member 10
6 is a sliding contact portion with the sliding portion 109. The diameter of the photosensitive drum and the developing roll which are usually used for the process cartridge was 20 to 30 mm. In recent years, with the miniaturization of process cartridges, the diameter of these rolls is 16 mm.
It is becoming below. When the roll diameter becomes smaller, the foot 111 of the sliding portion 109 has to be shortened. However, when the foot 111 of the sliding portion 109 is shortened, the spring effect is reduced. Therefore, stable contact cannot be made at the sliding portion. As a result, in the case of a photoconductor drum, an image defect due to a grounding defect occurs in the photoconductor drum, and in the case of a developing roll, an image defect due to a development bias defect occurs. Furthermore, even if the contact is mild enough not to cause an image defect, radio waves are generated from the sliding contact portion by repeating irregular contact and non-contact. There is a problem that the unnecessary radiated radio waves cause radio interference in electric devices around the image forming apparatus. This problem remarkably occurs in the developing roll section. This is because a high voltage electric field of several hundred volts is usually applied to the developing roll. Further, when an alternating electric field is applied to the developing roll, unnecessary radiation noise becomes more remarkable.

[0007]

In the conventional structure, the spring member is slid directly on the fixed shaft to establish conduction between the spring member and the fixed shaft. Therefore, when a conductive cylinder having a small diameter is used, the legs of the spring have to be shortened, and a sufficient spring effect cannot be obtained. Therefore, there is a problem that the contact is not stable at the sliding portion.

The present invention solves the above problems and stabilizes electrical contact between a conductive cylindrical base used in the process section of an electrophotographic image forming apparatus and a conductive fixed shaft of the cylinder. It is intended to prevent image defects and unnecessary radio wave interference caused as a result of unstable contact. The present invention is particularly effective when the conductive cylinder has a small diameter, and has an optimal structure for a small-sized photosensitive drum for an integrated process cartridge and a developing roller.

[0009]

According to the present invention, there is provided a conductive cylinder rotatably supported, an insulating flange member fitted to an end of the cylinder, and a conductive cylinder penetrating the inside of the cylinder. A fixed shaft, a conductive sliding plate having electrical continuity with the fixed shaft and provided perpendicular to the fixed shaft, and fixed to the flange member to electrically connect the cylinder and the sliding surface. It is a conductive roll for electrophotography composed of a spring member to be connected.

[0010]

In the present invention, the continuity between the spring member and the fixed shaft is established through the sliding plate provided perpendicularly to the fixed shaft. Therefore, the legs of the spring member can be lengthened even when a small-diameter cylinder is used. This stabilizes the contact on the sliding surface.

Further, in the conventional structure, the spring member is biased from the direction perpendicular to the fixed shaft. Therefore, when the cylinder moves in the thrust direction, it is possible to maintain a stable contact state. However, since the distance between the spring member and the fixed shaft changes with respect to the movement in the radial direction, a stable contact state cannot be maintained.

On the other hand, in the cylinder having the structure of the present invention, since the continuity between the spring member and the fixed shaft is mediated by the sliding plate provided perpendicularly to the fixed shaft, the movement of the cylinder in the thrust direction is prevented. On the other hand, the contact state is unstable, but a stable contact state can be maintained against movement in the radial direction. Therefore, the cylinder is not fixed to the fixed shaft provided on the flange member, but is suitable for the case of a cylinder configured to move in the radial direction.

[0013]

EXAMPLES Next, the construction of the electrophotographic conductive roll of the present invention will be described by way of examples.

Although all of the examples have been described as application examples to the developing roll, the constitution of the present invention can be applied to the photosensitive drum similarly to the example of the developing roll, and the same effect as the example. Have.

(Embodiment 1) FIG. 1 is a sectional view showing the entire structure of a developing roller of Embodiment 1, FIG. 2 is a perspective view showing a flange and a spring member in the embodiment, and FIGS. It is a perspective view which shows the shape of a moving plate.

In FIG. 1, 1 is a developing roller which is a conductive cylinder, 2 is a conductive fixed shaft around which a cylindrical magnet 3 is fixed, 4 and 5 are insulating flanges, and 6 is a conductive spring. The member 7 is a conductive sliding plate.

The developing roll 1 is a non-magnetic metal. In Example 1, a stainless steel cylinder having an outer diameter of 16 mm and t = 0.8 mm was used. The fixed shaft 2 is also a non-magnetic metal, and both ends are φ
8 has stepped surfaces perpendicular to the longitudinal direction of the fixed shaft 2 at 8 and 9. A gear 10 is integrally formed with the flange 4.

The shapes of the flange and the spring member will be described with reference to FIG. On the outer periphery of the flange 4, the cutout space portion 1
1, 12 and protrusions 13 and 14 are provided. The spring member 6 is t = 0.15 mm phosphor bronze, and the fixed shaft 2 is provided at the center.
A hole 15 of 5 mm penetrating through the hole 15 and holes 16 and 17 for fitting with the projections 13 and 14 provided on the flange member around the hole 15,
Contactors 18 for contacting the sliding plates and contactors 2 for the developing roll 1 corresponding to the spaces 11, 12 of the flange 4.
It has 0 and 21.

The sliding plate 7 shown in FIG. 3 is a disc of φ = 14 made of brass with t = 0.5 mm, and has a hole 24 having a cylindrical projection 22 formed by burring in the center. . The hole diameter of the hole 24 is smaller than the end diameter φ4 of the fixed shaft 2. The sliding plate 7 of FIG. 4 has a projection 23 having a claw shape, which is different from that of FIG.

Next, the function and effect of each member will be described while explaining the assembly procedure of these members.

First, the following two pre-operations are performed. (1) The sliding plate 7 shown in FIGS. 3 and 4 is press-fitted from one end of the fixed shaft, and is pushed up to the vertical step surface 8 provided on the fixed shaft 1. Positioned on the vertical step surface 8, the sliding plate 7 is fixed at a fixed position and in a direction perpendicular to the longitudinal direction of the fixed shaft 2.

(2) As shown in FIG. 2, after inserting the small holes 16 and 17 provided in the spring member 6 into the projections 13 and 14 of the flange 4, heat or pressure is applied to the projections 13 and 14 to crush them. The spring member 6 is fixed to the flange 4. At this time,
The spring contacts 20 and 21 provided on the outer circumference of the spring member 6 are accommodated in the cutout spaces 11 and 12 of the flange 4.

A flange 5 is fitted and fixed to one end of the developing roll 1. The fixed shaft 1 that has been subjected to the previous work (1) is inserted into the bearing provided on the flange 5. The fixed shaft 1 is inserted in one end on the side where the sliding plate is not press-fitted. next,
When the flange 4 that has been subjected to the previous work (2) is fitted into the other end of the developing roll, the contacts 20 and 21 of the spring member 6 are pressed against the inner surface of the developing roll and are accommodated in the cutout space of the flange 4. To be done.

Since the developing roller 1 shown in FIG. 1 is rotatably supported by the bearings of the flanges 4 and 5, it can rotate about the fixed shaft 2.

The developing roll 1 completed as described above
Is incorporated in an image forming apparatus, and a bias voltage is applied to the fixed shaft 2 by a bias terminal 25 in the image forming apparatus. The voltage applied from the bias terminal 25 is fixed shaft 2-sliding plate 7-contacts 18, 19-contacts 20, 21.
-Applied to the developing roll 1 via the path of the developing roll 1.

By reducing the diameter of the developing roll, in the developing roll having the conventional structure, the contact resistance is likely to be unstable on the sliding surface between the spring contact and the fixed shaft. Therefore,
Conventionally, an image defect problem due to unwanted radiation interference and a bias defect was caused, but the developing roll of Example 1 had no problem at all.

The sliding plate 7 of this embodiment is fixed to the fixed shaft 2 by a burring protrusion. In the case where the protrusion is not provided, the contact between the sliding plate 7 and the fixed shaft 2 is unstable, and unnecessary radiation noise is generated. If the vertical step surface 8 is enlarged, the vertical step surface 8 can also be used as a sliding plate.

(Embodiment 2) The developing roller of Embodiment 2 has a backup plate 26 inserted between a sliding plate 7 and a step surface 8 provided on a fixed shaft, and its cross-sectional structure is shown in FIG. 5
Shown in.

Backup plate 26 used in Example 2
Is a brass disc with t = 1.0 mm and φ14, and has a hole in the center that is slightly larger than the outer diameter of the fixed shaft. The purpose of the backup plate 26 is to improve the perpendicularity between the sliding plate 7 and the fixed shaft. The backup plate 26 is a disk having an outer diameter larger than the outer diameter of the vertical step surface. Therefore,
The backup plate 26 creates a vertical wall that is higher than the vertical step surface. Since the sliding plate 7 follows this wall, the verticality of the sliding plate 7 is improved. In addition, the backup plate 26
It is also possible to change the sliding pressure between the contacts 18 and 19 and the sliding plate 7 by adjusting the wall thickness of.

[0030]

According to the present invention, the continuity between the spring member and the fixed shaft is established through the sliding plate provided perpendicularly to the fixed shaft.
Therefore, the legs of the spring member can be lengthened even when a small-diameter cylinder is used. This stabilizes the contact on the sliding surface. Since the contact resistance on the sliding surface is small, it is possible to prevent unwanted radiation interference generated from the sliding portion.

Further, in the case where the periphery of the hole of the sliding plate is burred to form a projection and the sliding plate is press-fitted into the fixed shaft by the projection, the electric resistance between the sliding plate and the fixed shaft is small, More effective.

Further, by providing a vertical step surface for positioning the sliding plate on the fixed shaft, the positional accuracy and verticality of the sliding plate can be improved.

Further, by inserting the backup plate between the vertical step surface and the sliding plate, the work of press-fitting the sliding plate can be facilitated and the verticality can be improved.

Furthermore, in the conventional structure, the spring member is biased from the direction perpendicular to the fixed shaft. Therefore,
When the cylinder moves in the thrust direction, a stable contact state can be maintained. However, since the distance between the spring member and the fixed shaft changes with respect to the movement in the radial direction, a stable contact state cannot be maintained.
On the other hand, in the cylinder having the structure of the present invention, the spring member and the fixed shaft are electrically connected to each other through the sliding plate provided perpendicularly to the fixed shaft. Although the contact state is unstable, it is possible to maintain a stable contact state with respect to movement in the radial direction. Therefore, the cylinder is not fixed to the fixed shaft provided on the flange member, but is suitable for the case of a cylinder configured to move in the radial direction. Therefore, when the present invention is applied to the developing roll, only the developing roll is floated by the spacer ring means,
It is possible to make the gap constant with the photoconductor drum.
In the developing roller having such a structure, only the developing roller moves in the thrust direction, and the fixed shaft and the magnet fixed to the fixed shaft can be fixed, so that high-resolution developing capable of realizing an accurate developing gap is possible.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the overall configuration of a developing roll in Example 1 of the present invention.

FIG. 2 is a perspective view showing a flange member and a spring member according to the first embodiment of the present invention.

FIG. 3 is a perspective view showing the shape of a sliding plate in Embodiment 1 of the present invention.

FIG. 4 is a perspective view showing another shape of the sliding plate according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional view showing the overall structure of a developing roll according to Embodiment 2 of the present invention.

FIG. 6 is a diagram illustrating a conventional configuration in which a photosensitive drum is grounded.

[Explanation of symbols]

 1 Developing Roll 2 Fixed Shaft 4, 5 Flange Member 6 Spring Member 7 Sliding Plate 8, 9 Vertical Step Surface 22, 23 Projection on Sliding Plate 26 Backup Plate

Claims (9)

[Claims] 1. A conductive cylinder rotatably supported,
An insulative flange member fitted to the end of the cylinder, a conductive fixed shaft penetrating the inside of the cylinder, and a conduction with the fixed shaft, and perpendicular to the longitudinal direction of the fixed shaft. The conductive sliding plate provided and fixed to the flange member,
A conductive roll for electrophotography comprising a spring member electrically connecting the cylinder and the sliding plate. 2. The electronic device according to claim 1, wherein the sliding plate is a plate member having a hole around which a protrusion is formed, and the fixed shaft and the sliding plate are fixed by the hole and the protrusion. Conductive roll for photography 3. The conductive roll for electrophotography according to claim 2, wherein the protrusion has a cylindrical shape. 4. The conductive roll for electrophotography according to claim 2, wherein the protrusion has a plurality of claws. 5. The conductive roll for electrophotography according to claim 2, wherein the protrusions are formed by burring. 6. The conductive roll for electrophotography according to claim 1, wherein the fixed shaft has a step surface perpendicular to the longitudinal direction of the fixed shaft. 7. A plate member having an outer diameter larger than the outer diameter of the step surface is inserted between the vertical step surface and the sliding plate.
The electroconductive roll for electrophotography according to 1. 8. The flange member includes a bearing hole for a fixed shaft,
The electroconductive roll for electrophotography according to claim 1, wherein the electroconductive roll is a plastic integrally molded product having a gear. 9. The conductive roll for electrophotography according to claim 1, wherein the flange member has a bearing hole larger than the outer diameter of the fixed shaft.