JP3276757B2 - Contact type charge applying device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact type charging device used in an image forming apparatus such as an optical printer such as a laser printer using an electrophotographic process, a copying machine, and a facsimile apparatus.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus such as a laser printer, the surface of a drum-shaped or belt-shaped image carrier is charged by a charging device and then exposed by an exposure device to form an electrostatic latent image. Is formed, the latent image is visualized with a developer from a developing device, and then transferred onto a transfer material from a sheet feeding device using a transfer device, and fixed by a fixing device.

In recent years, a contact-type charge applying device called a charging roller or a transfer roller has been used as a charging device or a transfer device in such an image forming apparatus. When the contact-type charge applying device is used as a charging device for charging the image carrier, a predetermined voltage is applied to the charging roller in a state where the charging roller is in contact with the image carrier, so that the image carrier is charged. An electric charge is applied. When a contact-type charge applying device is used as a transfer device, a transfer material is transported between an image carrier carrying a developed image and a transfer roller pressed against the image carrier. Transferring the developed image from the image carrier to the transfer material by applying a voltage having a polarity opposite to the polarity of the developer on the image carrier to the roller. In any of the above cases, since the charge is applied to the member to be charged in a contact state, the amount of ozone generated in the contact-type charge applying device is remarkably higher than that in the conventional corona discharging method. Less.

[0004] By the way, the power supply to the charge applying roller in the contact type charge applying apparatus as described above is conventionally performed by applying a voltage to a conductive bearing. However, when a rolling bearing is used as the above-described bearing, toner enters between the outer ring and the inner ring to prevent conduction, and when a bearing made of a conductive resin is used, the resistance value of the resin itself varies. As a result, poor conduction may not be obtained due to poor conduction. In order to solve the above problem, a method of supplying power by directly contacting a conductive brush or a terminal with a shaft of a charge applying roller is disclosed in Japanese Unexamined Patent Publication No.
It has been proposed as seen in JP-A-3-197980 and JP-A-4-320281.

[0005] Further, in the contact type charge applying device using such a charge applying roller, the roller surface is contaminated by repeated use. This is mainly because toner is transferred and adhered from the image carrier due to the roller being in contact with the image carrier, and dust and toner floating in the apparatus due to the charged roller. Such as by adsorbing. When the roller surface is contaminated, the charge imparting property changes, and as a result, the image quality deteriorates. To solve this problem, Japanese Patent Laid-Open No. 2-272852 proposes to provide a scraper in contact with the roller surface in order to scrape foreign substances on the roller surface.

[0006]

However, in the above-described electric charge applying apparatus employing a system in which a conductive brush or a terminal is brought into direct contact with the shaft of the electric charge applying roller to supply power.
A mechanism for directly supplying power to the shaft of the charge applying roller must be provided exclusively, and a new problem of increasing the cost due to an increase in the number of parts has occurred.

[0007] The present invention has been made in view of the above points, and has as its object to provide a contact-type charge applying device which is reduced in cost by sharing the same.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a contact-type charge applying device provided with a charge applying roller which presses against an image carrier and applies an electric charge to the image carrier or a transfer material. A conductive cleaning member that abuts against the surface of the charge applying roller and cleans the surface;
Provided is a contact-type charge applying device having voltage applying means for applying a voltage to the voltage applying roller via the cleaning member in order to apply an electric charge to an image carrier or a transfer material.

In the contact type charge applying device, it is preferable that the cleaning member extends outside the end face of the charge applying roller.

[0010]

According to the present invention, a voltage is applied to the charge applying roller through a cleaning member that contacts the surface of the charge applying roller and cleans the surface. Good voltage application can be performed without providing a mechanism for applying a voltage to the charge applying roller.

According to the present invention, when a voltage is applied to the charge applying roller via a cleaning member that contacts the surface of the charge applying roller and cleans the surface, the cleaning is performed. -From above the end face of the ning member
The phenomenon that the current leaks to the battery is prevented.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 1 is a main part configuration diagram showing an example in which the contact-type charge applying device of the present invention is used for a charging device of an image forming apparatus.

In FIG. 1, a charging roller 2, which is one of the components of the contact-type charge applying device of the present invention, is made of a conductive elastic member, and is rotatable about a conductive core 3. And is provided in pressure contact with the photoconductor 1 as an image carrier. On the surface of the charging roller 2, a conductive thin blade 8 made of a metal plate or a foam such as conductive urethane is provided in contact with the thin blade 8. Is connected to a high-voltage power supply 9. At the time of image formation, when the photosensitive member 1 starts rotating in the direction of the arrow in the drawing, a voltage is applied to the conductive charging roller 2 from the high-voltage power supply 9 through the thin plate blade 8 and the charging roller 2 is turned on. Is photoconductor 1
The surface of the photoreceptor 1 is charged to a predetermined potential by being swung in the direction of the arrow by the frictional force between the photoreceptor 1 and the photoreceptor 1.

The photosensitive member 1 whose surface is uniformly charged
Is further rotated in the direction of the arrow in the figure, and the surface of the photoreceptor 1 is irradiated with exposure light 4 by an exposure device (not shown) to form a latent image. Is formed. The developed image formed on the surface of the photoconductor 1 is transferred to the transfer roller 6 by further rotation of the photoconductor 1.
A transfer roller (not shown) is transferred to a transfer material (not shown) which has reached a pressure contact portion between the photoconductor 1 and the pressing member (not shown).
The image is transcribed under the action of the laser 6. Here, the transfer material having received the transfer of the developed image is transported to a fixing device (not shown),
The transferred image on the transfer material becomes a fixed image under the action of the fixing device, and the image formation ends. On the other hand, although the residual developer which has not been transferred is present on the surface of the photoreceptor 1 on which the developed image has been transferred, the photoreceptor 1 is further rotated and a thin cleaning blade having elasticity is formed on the photoreceptor. The residual developer is removed from the surface of the photoconductor 1 by the action of the cleaning device 7 pressed against the surface of the photoconductor 1.

Here, the photosensitive member 1 is subjected to the action of the cleaning device 7 as described above to remove the residual developer on the surface thereof. There is a developer that passes through the pressure contact portion of the body 1. Then, the developer that has passed through the pressure contact portion between the cleaning blade and the photoreceptor 1 reaches the pressure contact portion between the charging roller 2 and the photoreceptor 1, which adheres to and adheres to the surface of the charging roller 2. The developer 10 is obtained. The deposited developer covers the surface of the charging roller 2 and thus hinders the charging action of the charging roller 2, and this effect appears as white stripes in the image.

Therefore, it is necessary to remove the developer adhered on the surface of the charging roller 2. In the present invention, the above-mentioned thin plate blade 8 functions to remove the developer.
That is, since the thin plate blade 8 is provided by pressing a plate-shaped member against the surface of the charging roller 2 having elasticity, as shown in FIG. The upper adhered developer 10 is scraped off satisfactorily.

As described above, in the present invention, the charging roller is
Since a member for applying a voltage to the roller 2 and a member for removing the adhered developer 10 on the surface of the charging roller 2 are commonly used, there is no need to provide a new member, and a large cost reduction can be achieved. became.

By the way, in providing the thin blade 8 of the present invention, as shown in FIG.
Is preferably extended a predetermined length (distance X in the drawing) outside the end of the transfer roller 2. Figure 3
When the end of the thin blade 8 is provided within a predetermined length (distance Y in the drawing) from the end of the transfer roller as shown in FIG. This is because, when a high voltage is supplied to 2, a leak as shown by 11 in FIG. Therefore, with the configuration described above, the occurrence of leakage is prevented and good charging can be obtained.

The above description has been made of an example in which the contact-type charge applying device of the present invention is used for a charging device of an image forming apparatus. However, the contact-type charge applying device of the present invention can be used for a transfer device with a similar configuration. In this case, if the transfer roller is made of a conductive elastic member similarly to the above-mentioned charging roller, and is rotatable around the conductive core metal and provided in the transfer portion while being in pressure contact with the photosensitive member. good. On the surface of the transfer roller, a conductive thin plate blade made of a metal plate or a foam such as conductive urethane is provided in contact with the surface as described above,
A high voltage power supply may be connected to the thin blade. Then, at the time of image formation, when the developed image formed on the photosensitive member reaches the transfer portion, a voltage may be applied from the high voltage power supply to the conductive transfer roller through the thin plate blade.
At this time, the transfer roller can transfer the developed image on the surface of the photoreceptor to a transfer material by giving a rotation due to a frictional force between the transfer roller and the photoreceptor. And
In such an image formation, the developer adhering to the transfer roller is satisfactorily removed as in the case of the charging roller described above. When the contact-type charge applying device of the present invention is used for both a charging device and a transfer device, the above-mentioned thin plate blade can be used as a common component.

[0020]

As described above, according to the present invention, the member for cleaning the surface of the charge applying roller is also used as a member for applying a voltage to the charge applying roller. , And a contact-type charge applying device with reduced cost can be obtained.

According to the present invention, in addition to the above, since the cleaning member extends outside the end face of the charge applying roller, the cleaning member abuts on the surface of the charge imparting roller and is in contact therewith. When a voltage is applied to the charge applying roller through a cleaning member that cleans the surface, a current leaks from the end face of the cleaning member to the charge applying roller. A highly reliable contact-type charge applying device which is prevented can be obtained.

[0022]

[Brief description of the drawings]

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

FIG. 2 is a main part configuration diagram showing an embodiment of the present invention.

FIG. 3 is a configuration diagram showing an object of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging roller 3 Charging roller core metal 4 Exposure light 5 Developing device 6 Transfer device 7 Cleaning device 8 Thin blade 9 High voltage power supply 10 Adhesive developer

Claims (2)

(57) [Claims] A contact-type charging device provided with a charge-providing roller for applying a charge to the image carrier or the transfer material by pressing against the image-bearing member; A conductive cleaning member for cleaning the surface,
Contact applying means for applying a voltage to the voltage applying roller via the cleaning member for applying an electric charge to the image carrier or the transfer material. apparatus. 2. A contact-type charge applying device according to claim 1, wherein said cleaning member extends outside an end face of said charge applying roller. Applicator.