JPS60130766A - Brush type electrostatic charging device - Google Patents

Abstract

PURPOSE:To prevent contactors of an electrostatic charging roller from setting and prevent the unevenness of charging by changing the directions of rotation of the charging roller in normal and reverse rotations every time the charging treatment is completed once or several times. CONSTITUTION:When a photosensitive drum 2 is charged, the charging roller 1 consisting of a roller body 1a and a fiber brush 1b is rotated as shown by an arrow A and a voltage is applied to the charging roller 1 to charge the surface of the photosensitive drum 2 by contact friction through tips of the fiber brush 1b. At this time, the charging roller 1 is reversed in the opposite direction of the arrow A every time the photosensitive drum 2 is charged once, so the force of contacting applied to the fiber brush 1 changes its direction and the fiber brush 1b is prevented from setting.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a charging device such as an electrophotographic copying machine, and particularly to a nibrush charging device.

[Prior art]

Conventionally, the main charging devices for electrophotographic copying machines, etc. are corona chargers that utilize corona discharge (although they are used in binary format,
It is dangerous because it requires a high voltage of about -3KV to 10KV during corona discharge, and ozone is generated during corona discharge, which has the disadvantage of damaging equipment around the charger.

Therefore, as an alternative to the conventional corona charger, brush charging devices have recently been actively developed. That is, in this device, a charging roller is formed by providing a large number of conductive contacts such as plated fiber brushes, metal brushes, or conductive fiber brushes on the roller surface, and while rotating this charging roller, The charging roller is brought into contact with the surface of the object to be charged, and a low voltage of about 500 V to 2 KV is applied to the charging roller to charge the object to be charged.

Therefore, compared to corona chargers, this brush charging device does not require high voltage and is therefore safer, and since it does not generate ozone, it has the advantage of not causing damage to surrounding equipment. There is.

However, in this device, since it is necessary to keep a contact such as a fiber brush in constant contact with the surface of the charged object, this contact pressure causes the contact to curl from its root and become sag. If used for a long period of time, uneven charging is likely to occur due to poor contact, and for example, in electrophotographic copying machines, there was a drawback that it adversely affected the copy image quality (1).

In addition, in the electrophotographic copying machine described above, toner remaining on the surface of the photoreceptor, which is the object to be charged, tends to adhere to the contactor.
When the amount of toner increases, the charging characteristics are adversely affected, and the surface of the photoreceptor is smeared with toner C, resulting in further deterioration of copy image quality.

[Purpose of the invention]

The present invention eliminates and improves these drawbacks of the prior art, and aims to provide a brush charging device that prevents the contacts provided on the charging roller from becoming sagging, thereby preventing uneven charging. It is something to do.

[Structure of the invention]

That is, the present invention involves rotating a charging roller provided with a large number of contacts having conductivity and bringing it into contact with the surface of an object to be charged, and applying a voltage to the charging roller. 1 In a brush charging device for charging a heavy object, the brush charging device is designed to be rotatable in the forward and reverse directions for a mini roller. By changing the direction of rotation, the contact 1 is prevented from deteriorating, thereby preventing uneven charging.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are side sectional views of a device in which the brush charging device of the present invention is incorporated as a charging device for a photosensitive drum of an electrophotographic copying machine.

That is, the brush charging device of the present invention has a roller main body (1a) and 4111 brushes (], 1) as shown in FIG.
) is provided in the vicinity of the photosensitive drum (2), which is the object to be charged.

First, the roller main body (la) is supported by a drive means (not shown) so as to be rotatable in forward and reverse directions, and is controlled by an appropriate control means so that the direction of rotation is reversed each time the photosensitive drum (2) is charged. It is configured to be connected to a power source (not shown) and to be able to apply voltage.

In addition, the outer peripheral surface of the roller body (1a) (second is carbon-dispersed acrylic fiber (manufactured by Toshisha Co., Ltd., 5A-7), carbon-dispersed nylon fiber (trade name: Beltron, manufactured by Kanebo Co., Ltd.), carbon-dispersed rayon fiber (trade name, manufactured by Unitika Co., Ltd.) The fabric (1c) is covered with a fabric (1c) in which a large number of fiber brushes (1b) made of conductive fibers such as
b) The tip portion is configured so as to come into contact with the surface of the photosensitive drum (2).

In order to charge a photosensitive drum using the brush charging device of the present invention, as shown in FIG.
) in the direction of the arrow (1 turn), and turn this charging roller (1 turn
) (Secondly, applying a voltage to the fiber brush (1b)
The tip of the photosensitive drum (2) can be electrically charged by contact friction with the surface of the photosensitive drum (2).

At this time, the charging roller (1) is connected to the photosensitive drum (2).
) is charged once, the direction of rotation is reversed,
As shown in FIG. 2, the direction of the two arrows B (one rotation) changes the direction of the contact pressure applied to the fiber blanket (lb) - 1, so that the fiber blanket (1b) can be prevented from becoming sagging.

Furthermore, since the direction of rotation of the charging roller (1) changes, the contact surface of the fiber brush (1b) that contacts the photosensitive drum (2) also changes, and compared to a conventional charging roller that rotates only in one direction, the fiber brush ( ] b) Since the distance traveled by the fiber brush (lb) increases, the I/N that has adhered to the fiber brush (lb) is naturally removed. Therefore, it is also possible to prevent toner from adhering to the fiber IsO brush. However, it goes without saying that it is also possible to have a configuration in which the charge is changed by one every time the charging process is performed.

Next, FIG. 3 shows the relationship between the number of copies and the wear and tear of the fiber brush in the blank charging device (a) according to this embodiment and the conventional brush charging device (b). Note that the amount of settling means the rate of change in the outer diameter of the fiber brush in the brush charging device.

As is clear from this graph result (2. In the conventional brush charging device (b), the amount of fatigue of the fiber brush increases in proportion to the number of copies (2). In contrast, in the brush charging device (A) according to the above embodiment, the settling amount is significantly reduced, and it is about 3 coefficient for one copy of 2 million copies, and the setting is 2. Even after using the battery for a long period of time, uneven charging occurs, indicating that it is difficult to charge.

〔Effect of the invention〕

As described above, the brush charging device of the present invention is capable of forward and reverse rotation of the charging roller. Since the direction of the contact pressure applied to the contact of the charging roller also changes each time, it is possible to prevent the contact from sagging.

Therefore, even after long-term use, stable charging is possible because uneven discharge due to poor contact does not occur, and durability can be greatly improved. When applied to a "-distribution contactor", the practical effects of the present invention are great, such as the fact that toner does not easily adhere to the surface of the photoreceptor, thereby eliminating the possibility of contaminating the surface of the photoreceptor with toner.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention, and FIGS. 1 and 2 are side cross-sectional views of the brush charging device of the present invention, and FIG. 3 is a relationship between the number of copies and the set-up of the fiber bran. FIG. Code explanation (1a)...Roller body (lb)...
・Textile Mi brush (1c)...Textile (1)...
...Charging roller (2) ...Photosensitive drum Patent applicant Fuji Xerox Co., Ltd. Agent Patent attorney Tomohiro Dochu 4.1 Same person Katsuo Naruse Figure 1 Figure 2 Figure 3 Hubi-masu Maki --- Kazuichi --- Continued from page 1 @ Inventor Tsu 1) Mae On @ Inventor Katsuno Ryuji @ Inventor Haruyuki Namba 0 Inventor Yama 1) Kotoku 2274 Hongo, Ebina City Fuji Xerox Co., Ltd. Ebina Factory 2274 Hongo, Ebina City Inside Fuji Xerox Co., Ltd. Ebina Factory 2274 Hongo, Ebina City Inside Fuji Xerox Co., Ltd. Ebina Factory 2274 Hongo, Ebina City Inside Fuji Xerox Co., Ltd. Ebina Factory

Claims (1)

[Claims] A charging roller is provided with a large number of electrically conductive contacts on the surface of the roller, and is brought into contact with the surface of the charged object while rotating, and a voltage is applied to the charging roller to charge the charged object.Brush charging A brush charging device characterized in that the direction of rotation of the charging roller can be rotated in forward and reverse directions (forming a plate), and the direction of rotation of the charging roller can be changed for each charging process once or for a plurality of times.