JPH04274452A - Process cartridge - Google Patents

Abstract

PURPOSE:To eliminate the need of a troublesome operation for exchanging parts and to improve productivity in the case of assembling a process cartridge by making an electrostatic charging unit provided with a contact electrostatic charging member attachable/detachable with respect to the process cartridge. CONSTITUTION:An electrostatic charging roller 2 which comes in contact with a photosensitive drum 1 is provided in a housing 7 with a feed part 9 so as to be constituted as the electrostatic charging unit. The electrostatic charging unit is easily attached to or detached from the process cartridge after the cover 16 of the process cartridge is detached. Thus, conduction between the roller 2 and the feed member 9 is checked as the unit state. Therefore, the parts which are defective in the conduction are not incorporated in the process cartridge and the operation for disassembling the process cartridge or exchanging the parts is eliminated.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process cartridge that is detachably mountable to an image forming apparatus, and more particularly to the structure of a charging means provided in the process cartridge.

0002

2. Description of the Related Art As described in Japanese Patent Publication No. 62-33581, this type of process cartridge includes a charging device, a developing device, a photosensitive drum as an image carrier, and a charging device, a developing device, etc.
At least one of the process means such as a cleaning device is provided integrally within the same housing, and the unit is detachably attached to the image forming apparatus. This facilitates maintenance by replacing the entire process cartridge.

By the way, as for the charging device installed in such a process cartridge, in place of the conventionally used corona discharger, in recent years, a contact charger such as a charging roller that charges the photosensitive drum by contacting it has been widely used. It's starting to look like this.

When a conventional corona discharger is used, the voltage applied to the wire electrode is a high voltage of about 4 kV to 8 kV, and most of the current flows from the wire electrode to the shield electrode, resulting in low charging efficiency and a large amount of corona discharge. However, by using a contact charger such as the above-mentioned charging roller, the problems of conventional corona dischargers can be overcome. I was able to resolve it.

[0005]

However, since the conventional charging roller is directly held in the housing of the process cartridge, it has the following drawbacks.

(1) When there is a conduction failure in the conductive portion for applying voltage to the charging roller and the photosensitive drum cannot be charged normally, the process cartridge itself becomes unusable.

(2) Once the process cartridge is disassembled to make it usable,
Defective parts must be replaced.

(3) The edge portion where the cleaning blade in the cleaning device installed in the process cartridge contacts the photosensitive drum usually has no toner attached to the photosensitive drum when it is new, so the photosensitive drum does not rotate. A lubricant containing fluorine-based powder is applied to the cleaning blade to prevent it from curling up when it starts cleaning. Therefore, the powder adheres to the surface of the charging roller at an early stage, causing charging failure in that area and making it impossible to obtain a normal image.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a process cartridge which eliminates the above-mentioned conventional drawbacks.

That is, the present invention, which achieves the above object, provides a process cartridge that includes an image bearing member and a charging means for charging the image bearing member, and is removably attached to an image forming apparatus. A charging member that contacts the body to charge the image carrier, a support member that supports the charging member, and a member that supplies power to the charging member as one unit,
This unit is characterized in that it can be attached to and detached from the process cartridge.

[0011]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings.

FIG. 1 shows a process cartridge that can be freely attached to and detached from an image forming apparatus.

In the figure, a photosensitive drum 1 serving as an image carrier rotates in the direction of the arrow, and is uniformly charged by a charging roller (contact charging member) 2 that rotates in contact with the photosensitive drum 1. The photosensitive drum 1 is irradiated with a laser beam 10 from a laser scanning device (not shown), and an electrostatic latent image is formed on the photosensitive drum 1 according to image information. Further, an elastic blade 13 is placed on the developing sleeve 12 of the developing device 11.
The electrostatic latent image on the photosensitive drum 1 is developed and visualized using toner powder whose layer thickness is regulated by the toner powder. The visualized toner image is fed by a paper feed roller (not shown), and is transferred by a transfer roller (not shown) onto a sheet material that is conveyed in synchronized timing with a pair of registration rollers (not shown). The sheet material onto which the toner image has been transferred is fixed by a fixing device (not shown). On the other hand, the toner remaining on the photosensitive drum 1 after the transfer is cleaned by the cleaning blade 15 of the cleaning device 14.

By the way, in this embodiment, the charging roller 2 that contacts the photosensitive drum 1 is connected to the power supply member 9 as shown in FIG.
It is also provided in the housing 7 and is configured as a charging unit.

The charging unit will be described in more detail below. The charging roller 2 has a conductive elastic layer on a core metal, a high-resistance elastic layer thereon, and a protective film on the surface. The core metal parts 2a and 2b at both ends of the charging roller 2 each have a bearing 3.
, 4 are slidably supported. The bearings 3 and 4 are respectively engaged with guide rods 7a, 7b and 7c, 7d in the housing 7, and are movable in the vertical direction. Here, the material of the bearing 4 is conductive resin. Compression springs 5 and 6 are provided between the bearings 3 and 4 and the housing 7.
, 4, the charging roller 2 is pressed against the photosensitive drum 1 with a predetermined pressure. A metal power supply member 9 is provided between the compression spring 6 and the housing 7, and its end 9a is connected to a high-voltage power source on the image forming apparatus side (not shown) to supply approximately 400V to the charging roller 2. A high voltage of ~2kV is supplied.

The housing provided with the charging roller 2, the power supply member 9, etc. as described above is configured to be easily attached to and detached from the process cartridge as a charging unit.

FIG. 3 shows the charging unit installed. However, in FIG. 3, the cover 16 of the process cartridge shown in FIG. 1 is removed from the process cartridge.
The developing device 11 is omitted from the illustration.

The photosensitive drum 1 is rotatably supported by both side plates 17, 17 of the container of the cleaning device 14. Elastic claws 17a, 17b, 17c, 1 for fixing the housing 7 of the charging unit are provided on the upper parts of the side plates 17, 17.
7d, and grooves 7e and 7 are provided in the housing 7 of the charging unit at positions corresponding to the respective elastic claws 17.
f (see FIG. 2) is formed.

When mounting the charging unit, the charging unit can be easily mounted by aligning the elastic claws with the grooves and pushing the charging unit against the biasing force of the elastic claws.

On the other hand, when removing the charging unit, the charging unit can be easily removed by raising the hook portion of the elastic claw.

In this manner, the charging unit can be easily attached to and detached from the process cartridge after removing the cover 16 of the process cartridge.

[0022] This makes it possible to check the conductivity between the charging roller 2 and the power supply member 9 in the unit state, and therefore, items with poor conductivity are not incorporated into the process cartridge, unlike the conventional process cartridge. There is no need to disassemble or convert parts. In addition, as for the problem caused by the lubricant attached to the edge of the cleaning blade adhering to the charging roller, the charging unit can be easily inserted into the housing of the process cartridge after the photosensitive drum has rotated once and the lubricant has disappeared from the photosensitive drum. There is no problem because it can be attached to.

In the above-described embodiments, a roller-shaped contact charging member is shown, but the contact charging member is not limited to this, and may be a blade-shaped member.

Further, in this embodiment, the process cartridge has a developing means and a cleaning means in addition to the charging means as the process means, but the present invention is not necessarily limited to this.

Further, in consideration of the influence of the lubricant as described above, it is preferable to apply the present invention to a process cartridge having a cleaning means employing a blade cleaning method.

[0026]

[Effects of the Invention] As explained above, according to the present invention,
By making the charging unit with a contact charging member removable from the process cartridge, it is possible to check for defects in the unit before it is incorporated into the process cartridge, eliminating the need for parts replacement, which was a problem in the past. No more complicated work required. Therefore, it is expected that productivity will be improved when assembling the process cartridge.

Further, according to the present invention, it is possible to prevent charging failures caused by contamination of the contact charging member with lubricant or the like.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of a process cartridge of the present invention.

FIG. 2 is a perspective view showing a charging unit that is detachable from the process cartridge of the present invention.

FIG. 3 is a perspective view showing a state in which a charging unit is attached.

[Explanation of symbols]

1 Photosensitive drum 2　Charging roller 3,4 Bearing 7 Charging unit housing 9 Power supply member 11 Developing device 14 Cleaning device

Claims (4)

[Claims] 1. A process cartridge that includes an image bearing member and a charging means for charging the image bearing member, and is removably attached to an image forming apparatus, wherein the charging means contacts the image bearing member and charges the image bearing member. A charging member that is charged, a support member that supports the charging member, and a member for supplying power to the charging member are included as one unit, and this unit is removably attached to the process cartridge. process cartridge. 2. The process cartridge according to claim 1, wherein the process cartridge has a cleaning means having a cleaning blade that comes into contact with the image carrier to clean the surface of the image carrier. 3. The process cartridge according to claim 2, wherein a lubricant is applied to a portion of the cleaning blade that contacts the image carrier. 4. The process cartridge according to claim 1, wherein the process cartridge has a developing means for forming a toner image on an image carrier.