JP2002156810A - Electrifying roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrifying roll capable of suppressing defective electrification due to the rust, as to the electrifying roll for electrifying an object to be electrified while rotating in contact with the object to be electrified, and which is provided with a cylindrical body whose surface is provided with an elastic layer on which a voltage is applied and a shaft passing through the axial center of the cylindrical body. SOLUTION: As for the shaft 122, rust preventive agent 123 are separately applied on the shaft parts where both ends of the cylindrical body 121 are positioned.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of applying a charge to an object to be charged by rotating in contact with the object. And a shaft passing through the axis of the cylindrical body.

[0002]

2. Description of the Related Art In image formation in a conventionally known image forming apparatus, first, an input image signal is subjected to gradation processing, and an electrostatic latent image is formed on a photosensitive member based on the signal. . Next, the electrostatic latent image on the photoconductor is developed by transferring the toner stored in the developing device to the photoconductor, thereby forming a toner image on the photoconductor. Further, the image is finally formed on the recording medium by transferring and fixing the toner image formed on the photoconductor on a predetermined recording medium.
In such image formation, it is necessary to previously charge the photosensitive member to a predetermined potential before forming an electrostatic latent image on the photosensitive member. In transferring a toner image onto a recording medium, it is sometimes necessary to charge the recording medium to be transferred to a potential having a polarity opposite to the potential of the toner forming the toner image.

[0003] Therefore, an image forming apparatus includes a charging roll having a cylindrical body having an elastic layer to which a voltage is applied on its surface, a conductive shaft penetrating the axis of the cylindrical body, and rotating both ends of the shaft. A bearing portion that freely supports the shaft, and a power supply member that contacts one end of the shaft and applies a voltage to the elastic layer, and rotates the cylindrical body in contact with a charged object such as a photoconductor or a recording medium. In some cases, a charging device that gives a charge to the object to be charged is used.

By the way, in such a charging device,
If rust is generated on a sliding portion of the shaft with the bearing portion or a contact portion with the power supply member, a rotation failure or a power supply failure may be caused, and a charging failure may be caused.

[0005] Therefore, conventionally, the shaft is made of stainless steel or electroless nickel plated.

[0006]

However, when paper is used as the recording medium, heat is sometimes applied to fix the toner image transferred to the paper, and the heat contained the paper. Water evaporates in the device, and the humidity in the device tends to increase. Further, the humidity inside the device may increase depending on the installation environment of the device. If the charging roll is exposed to high humidity for a long time, moisture in the atmosphere may permeate the elastic layer. Here, the elastic layer is used to improve its performance.
It is often made of a special material containing a strongly acidic substance, and the water soaked pushes out the strongly acidic substance contained in the elastic layer, and this strongly acidic substance may adhere to the shaft. If a strong acid substance adheres to the shaft, rust may be generated on the shaft sliding part with the bearing part or the contact part with the power supply member simply by using stainless steel or electroless nickel plating on the shaft. It is difficult to stop.

Therefore, in order to prevent the strongly acidic substance from being extruded, a technique of applying a coating film on the surface of the elastic layer may be adopted. However, if the coating film is thickened, the original function of the elastic layer may be impaired. Therefore, it was not possible to apply a coating film to obtain a sufficient effect.

Although the charging roll of the image forming apparatus based on the electrophotographic technique has been described so far, the charging roll for the charging process in the general equipment is also similarly used for the shaft for the above-mentioned reason. In some cases, rust is generated on a sliding portion with the bearing portion and a contact portion with the power supply member, which may cause poor charging.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a charging roll which is less likely to cause charging failure due to rust.

[0010]

Means for Solving the Problems The first charging roll of the present invention, which achieves the above object, provides a charge to the object by rotating while being in contact with the object. In a charging roll having a cylindrical body having an elastic layer to which a voltage is applied on its surface and a shaft penetrating the axis of the cylindrical body, the shaft is:
A rust preventive is applied to portions of the shaft where both ends of the cylindrical body are located.

The second charging roll of the charging roll of the present invention that achieves the above object imparts a charge to the charged object by rotating while being in contact with the charged object, In a charging roll having a cylindrical body having an elastic layer on the surface to which a voltage is applied and a shaft penetrating the axis of the cylindrical body, the shaft is provided with a rust preventive agent on a portion of the shaft protruding from the cylindrical body. The third charging roll among the charging rolls of the present invention, which achieves the above object, rotates while being in contact with the object to be charged, thereby charging the object to be charged. And a charging roll having a cylindrical body having an elastic layer to which a voltage is applied on its surface and a shaft penetrating the axis of the cylindrical body,
It is characterized by having a rust prevention member fitted to a portion protruding from the cylindrical body.

[0012] Further, the fourth charging roll of the charging roll of the present invention that achieves the above object imparts a charge to the charged object by rotating while being in contact with the charged object, In a charging roll having a cylindrical body having an elastic layer to which a voltage is applied on its surface and a shaft penetrating the axis of the cylindrical body, the shaft is provided at a portion of the shaft protruding from the cylindrical body. The fifth charging roll among the charging rolls of the present invention, which achieves the above object, is rotated in a state of being in contact with the object to be charged. A charging roll for applying an electric charge to the object to be charged and having a cylindrical body having an elastic layer to which a voltage is applied on a surface thereof, and a shaft penetrating the axis of the cylindrical body; Shift is of the shaft, the protruding part from the cylinder, and characterized in that the circumferential groove around the shaft is formed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing an embodiment of the charging roll of the present invention, an image forming apparatus as an example of an apparatus employing the charging roll of the present invention will be described with reference to FIG.

FIG. 1 is a schematic structural view of an image forming apparatus employing the charging roll of the present invention.

The image forming apparatus 1 shown in FIG. 1 is a printer, and includes a photosensitive member 11, a charging roll 12, an exposure device 1
3, a developing device 14 having a developing roll 141, a transfer roll 15, a fixing roll 16, a cleaning blade 17, a paper cassette 18, a manual feed mechanism 19, two feed rolls 20, a registration roll 21, and an exit roll 22.
It has.

In the image forming apparatus 1, the charging roll 12
After the photoconductor 11 is charged to a predetermined potential, the exposure device 13 irradiates a laser beam corresponding to image information (an arrow indicated by a dashed line in the figure) to form an electrostatic latent image on the surface of the photoconductor 11. Is done. This electrostatic latent image is developed by the toner carried by the developing roll 141 of the developing device 14, and a toner image is formed on the surface of the photoconductor 11. Further, the paper stored in the paper cassette 18 or the paper inserted in the manual feed mechanism 19 is used as a recording medium.
The paper is fed toward the inside of the apparatus by the feed roll 20. The fed sheet is conveyed between the photoreceptor 11 and the transfer roll 15 by the registration roller 21 correcting the posture and timing of paper feeding. The toner image on the surface of the photoconductor 11 is transferred by the transfer roll 15 to the paper conveyed between the photoconductor 11 and the transfer roll 15, and the transferred toner image is fixed by the fixing roll 16 and A print image is formed thereon. The sheet on which the print image is formed is sent out of the apparatus by the exit roll 22. The untransferred toner remaining on the surface of the photoconductor 11 after the transfer process is removed by the cleaning blade 17, and after the surface of the photoconductor 11 is neutralized by an unillustrated static eliminator, the charging roller 12 is again charged.
To the charging step.

Subsequently, referring to FIG. 2 and FIG.
A contact charging method, which is one of the methods for charging the charging device 1, will be described.

FIG. 2 is a top view of the housing in which the photosensitive member and the charging roll of the present invention are supported from above, and FIG.
FIG. 4 is a diagram showing one end of a charging roll attached to a housing.

To charge the photoconductor 11 using the charging roll 12 by the contact charging method, the charging roll 12 is disposed so as to be in contact with the surface of the photoconductor 11, and the charging roll 12 is charged.
And a discharge is generated in a minute gap near the contact portion.

A photosensitive member 11 is rotatably supported on a housing 100 shown in FIG. The charging roll 12 is
It has a cylinder 121 having an elastic layer 1211 on its surface, and a shaft 122 penetrating through the axis of the cylinder.
Both ends of the shaft 122 are supported by bearings 101 shown in FIG. 3 provided on the housing 100 so that the shaft 122 is parallel to the axis of the photoconductor 11. The elastic layer 1211 is made of a special material containing a strongly acidic substance in order to improve its performance. Shaft 12
No. 2 has conductivity, and is made of stainless steel or stainless steel plated with electroless nickel in order to improve corrosion resistance. Further, the pressing spring 1 shown in FIG.
The cylindrical body 121 is pressed and urged against the photoconductor 11 by 02 and linearly contacts the photoconductor 11, and the charging roll 12 rotates following the rotation of the photoconductor 11. A leaf spring-shaped power supply member 103 is in contact with one end of the shaft 122, and a predetermined voltage (DC voltage + AC voltage) from a voltage application power supply (not shown) is applied to the power supply member 103, whereby 11 is charged to a required potential. In addition,
Instead of the leaf spring-shaped power supply member 103, a pressing spring 102
The bearing 101 may be made of a conductive material, and these may be used as a power supply member.

Next, a description will be given of the result of analyzing the mechanism of rust generation on the sliding portion of the shaft 122 with the bearing portion 101 and the contact portion with the power supply member 103. First, shaft 1
Most of the rust generated in the elastic layer 21 is generated by the strong acid substance in the elastic layer, which is pushed out by the water soaking into the elastic layer 1211, and adheres to the shaft 122. Of the extruded strongly acidic substances, those that adhere to the shaft 122 are often extruded from both end surfaces of the elastic layer 1211. When the strongly acidic substance adheres to the shaft 122, the cylindrical body 121 Adheres along the end face of
The strongly acidic substance adhering to the shaft 122 is likely to stay in portions of the shaft 122 where both ends of the cylindrical body 121 are located, and first, rust is generated in this portion.
As time passes, the generated rust is generated on the shaft 12.
2 and finally, the shaft 122 slides with the bearing 101 and the power supply member 103.
And reaches the contact portion.

Hereinafter, the charging roll of the present invention will be described in the first
A description will be given using the embodiments to the fifth embodiment. In the following description, the same components as those described above are denoted by the same reference numerals.

First, the first of the charging rolls of the present invention is used.
A charging roll corresponding to the charging roll described above will be described with reference to FIG.

FIG. 4 is a view showing the charging roll of the first embodiment. In FIG. 4, for convenience of explanation, the cylindrical body 12
1 is indicated by a dashed line.

The shaft 122 of the charging roll 12 according to the first embodiment is obtained by applying a rust preventive agent 123 such as paint to both ends of the cylindrical body 121 of the shaft 122.
Therefore, rust generated on the shaft 122 can be cut off from the beginning. In addition, the elastic layer 1211 conventionally used to prevent the strongly acidic substance from being extruded.
Is difficult to apply to the end surface of the elastic layer 1211. However, in the present embodiment, by dealing with the shaft 122 side, it is possible to make it difficult to generate rust. Furthermore, since the rust preventive agent 123 may be applied to a limited range of both ends of the cylindrical body 121 of the shaft 122, even if the rust preventive agent 123 has insulating properties, Conductivity to the body 121 can be ensured.

Subsequently, the second of the charging rolls of the present invention
The charging roll corresponding to the charging roll described above will be described with reference to FIG.

FIG. 5 is a view showing a charging roll of the second embodiment.

The shaft 122 of the charging roll 12 according to the second embodiment is obtained by applying a rust preventive agent 124 such as paint to a portion of the shaft 122 protruding from the cylindrical body 121.

A charging roll corresponding to a third charging roll of the charging roll of the present invention will be described with reference to FIG.

FIG. 6 is a view showing a charging roll according to the third embodiment.

The charging roll 12 of the third embodiment has a rust preventive member 125 made of rubber or the like fitted on a portion of the shaft 122 protruding from the cylindrical body 121.

In the second and third embodiments, even if rust is generated on the shaft 122 where both ends of the cylindrical body 121 are located, the applied rust preventive agent 124 or the fitted rust preventive The member 125 can suppress the growth of rust. In the third embodiment shown in FIG.
The rust preventive member 125 is fitted so as to be in contact with the end face of the cylindrical body 121. Therefore, the rust preventive member 125 prevents the strong acid substance from being extruded instead of the conventionally used coating layer. And rust can be hardly generated.

Next, a charging roll corresponding to a fourth charging roll of the charging roll of the present invention will be described with reference to FIG.

FIG. 7 is a view showing a charging roll according to the fourth embodiment.

The shaft 122 of the charging roll 12 according to the fourth embodiment has a portion protruding from the cylindrical body 121 of the shaft 122.
And a ridge 126 formed integrally therewith.

A charging roll corresponding to the fifth charging roll of the charging roll of the present invention will be described with reference to FIG.

FIG. 8 is a view showing a charging roll according to the fifth embodiment.

The shaft 122 of the charging roll 12 according to the fifth embodiment is formed by forming a circumferential groove 127 around the shaft 122 at a portion of the shaft 122 protruding from the cylindrical body 121.

In the fourth and fifth embodiments, even if rust is generated on the shaft 122 where both ends of the cylindrical body 121 are located, the ridge 126 and the circumferential groove 127 are formed.
It takes time for the rust to reach the sliding portion of the shaft 122 with the bearing portion 101 and the contact portion with the power supply member 103 due to the presence of the charging roller 12. Is the bearing portion 101 of the shaft 122.
, And the possibility of reaching the contact portion with the power supply member 103 can be reduced.

In each of the above embodiments, the elastic layer 1
A coating film which has been conventionally used may be applied to the surface of 211 to prevent the strongly acidic substance from being extruded.

Although the charging roll 12 of the image forming apparatus 1 has been described above as an example, in the image forming apparatus 1, in addition to the charging roll 12, the transfer roll 15 described with reference to FIG. The present invention can be applied to the transfer roll 15, and the charging roll of the present invention is not limited to the image forming apparatus 1, and is widely used as a charging roll for a charging process in general equipment. Can also be applied.

[0042]

As described above, according to the present invention, it is possible to provide a charging roll which is less likely to cause poor charging due to rust.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus employing a charging roll of the present invention.

FIG. 2 is a top view of a housing in which a photosensitive member and a charging roll of the present invention are pivotally supported.

FIG. 3 is a diagram showing one end of a charging roll attached to a housing.

FIG. 4 is a diagram showing a charging roll of the first embodiment.

FIG. 5 is a diagram illustrating a charging roll according to a second embodiment.

FIG. 6 is a diagram illustrating a charging roll according to a third embodiment.

FIG. 7 is a diagram illustrating a charging roll according to a fourth embodiment.

FIG. 8 is a diagram illustrating a charging roll according to a fifth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming apparatus 11 Photoreceptor 12 Charging roll 121 Cylindrical body 1211 Elastic layer 122 Shaft 123 Rust preventive agent 124 Rust preventive agent 125 Rust preventive member 126 Protrusion strip 127 Circumferential groove 13 Exposure device 14 Developing device 15 Transfer roll 16 Fixing roll 17 Cleaning blade 18 Paper cassette 19 Manual feed mechanism 20 Feed roll 21 Registration roll 22 Exit roll 100 Housing 101 Bearing unit 102 Pressure spring 103 Power supply member

Claims (5)

[Claims] 1. A cylindrical body having an elastic layer to which a voltage is applied on a surface thereof, wherein the cylindrical body has an elastic layer to which a voltage is applied. And a shaft through which a rust inhibitor is applied to portions of the shaft where both ends of the cylindrical body are located. 2. A cylinder having an elastic layer to which a voltage is applied on a surface thereof, the cylinder having an elastic layer to which a voltage is applied, and an axial center of the cylinder being rotated by rotating while being in contact with the object. And a shaft that penetrates the cylindrical body, wherein the shaft is formed by applying a rust preventive agent to a portion of the shaft protruding from the cylindrical body. 3. A cylinder having a surface on which an elastic layer to which a voltage is applied is provided, by applying a charge to the object to be charged by rotating while being in contact with the object to be charged, and an axis of the cylinder. A charging roller having a rust-preventive member fitted to a portion of the shaft protruding from the cylindrical body. 4. A cylinder having an elastic layer to which a voltage is applied on a surface thereof and a cylinder having an elastic layer to which a voltage is applied, the cylinder being rotated while rotating in contact with the object. A charging roller having a shaft penetrating the shaft, wherein the shaft has a portion protruding from the cylindrical body of the shaft, and a protruding strip extending around the shaft is formed on the shaft. . 5. A cylindrical body having an elastic layer to which a voltage is applied on a surface thereof, wherein the cylindrical body has an elastic layer to which a voltage is applied, by rotating while rotating in contact with the charged body, and an axis of the cylindrical body. And a shaft that penetrates the cylindrical body, wherein the shaft has a portion protruding from the cylindrical body of the shaft and a circumferential groove surrounding the shaft formed therein.