JPH0536454U - Charging device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a charging device capable of suppressing a rotation torque to a low level and not damaging a surface of a charging member or a contact surface of a cleaning member due to abrasion. [Structure] The charging roller 4 is separated from the photosensitive drum 2 by a separating member 30 and is brought into contact with the cleaning member 27. The charging roller 4 is rotated in association with the operation of the separating member 30 to clean the charging roller 4.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a charging device.

[0002]

[Prior Art]

 Conventionally, as a method for uniformly charging the surface of a charged member such as a photoconductor as an electrostatic latent image carrier or a transfer material in an image recording apparatus using an electrophotographic process such as an electrophotographic copying machine or a laser beam printer. It was common to use a corotron or a scorotron that uses corona discharge. This is to apply a high voltage of 5 to 10 kV to a thin metal wire such as tungsten to cause a corona discharge phenomenon due to local dielectric breakdown of air, and move the generated ions to the surface of the charged member to be charged. Is.

However, since corotrons and scorotrons generate a large amount of ozone due to the use of corona discharge, ozone removal devices such as ozone filters are required, and the applied voltage is high and the power supply is large and expensive. There was a flaw.

Therefore, in recent years, roller charging using a conductive rubber has been extensively studied, and some of them have been put to practical use (for example, JP-A-54-150131 and JP-A-56). -132356 gazette etc.).

This is because a conductive rubber, in which a conductive material such as carbon black or metal powder is dispersed, is fixed to a metal core of a conductive metal via a conductive adhesive, and 0.5 The charging is performed by applying a voltage of about 2 kV to the surface of a member to be charged such as a photoconductor and rolling the member while pressing it.

The charging device using this charging roller has advantages that the applied voltage can be small, a small power source can be used, an inexpensive one can be used, and almost no ozone is generated.

However, it is unavoidable that fine paper powder, rosin, talc, and other deposits generated from paper that is frequently used as a transfer material adhere to the charging roller due to repeated use of the charging roller. Since the roller is charged, dust and toner floating in the device may be adsorbed, which may cause uneven charging.

In order to solve these problems, a method has been devised in which a cleaning member is brought into contact with the charging roller to remove foreign matter on the surface of the charging roller (for example, Japanese Patent Laid-Open No. 2-272582).

[0009]

[Problems to be solved by the device]

 However, the cleaning member of the above invention is always in contact with the charging roller, and there are problems that the rotating torque increases and both surfaces are worn due to the friction between the surface of the charging roller and the contact surface of the cleaning member. ..

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a charging device that suppresses the rotating torque to a low level and does not damage the surface of the charging roller and the cleaning member.

[0011]

[Means for Solving the Problems]

 In order to achieve this object, the charging device of the present invention comprises a cleaning member for cleaning the surface of the charging member, the charging member is separated from the electrostatic latent image carrier, and is brought into contact with the cleaning member. And a charging member moving means.

[0012]

[Action]

 In the charging device of the present invention having the above structure, the charging member and the cleaning member are separated from each other during normal use, and the charging member and the electrostatic latent image carrier are separated by the charging member moving means only during cleaning. Cleaning is performed by contacting the cleaning member.

[0013]

Embodiment An embodiment embodying the present invention will be described below with reference to the drawings.

First, referring to FIG. 1, a process unit 1 of a laser printer equipped with the charging device of the present invention will be described.

The process unit 1 according to the present embodiment mainly includes a photosensitive drum 2, a charging roller 4, a developing sleeve 8, and a cleaning blade 18.

The photoconductor drum 2 rotates in the direction of arrow a, and the contact type charging roller 4 first charges the surface thereof to about −700V. The charging roller 4 is rotated by the rotation of the photosensitive drum 2. Then, the laser beam 6 emitted from a laser light emitting element (not shown) lowers the potential of only the characters or figures on the photosensitive drum 2 to about -100V. Further, the toner 10 is carried to the developing area by the developing sleeve 8 to visualize the electrostatic latent image on the photosensitive drum 2. This image is transferred onto the paper 14 by the transfer roller 12 provided on the laser printer side. At this time, 100% of all the toner is not transferred, so about 10% of the untransferred toner remaining on the surface of the photosensitive drum 2 is scraped off by the cleaning blade 18.

Next, a pressing mechanism of the charging roller 4 to the photosensitive drum 2 will be described.

As shown in FIG. 2, both ends of the rotary shaft 20 of the charging roller 4 are configured to be received by bearings 22 (only one side is shown in FIG. 2). A holder 24 provided on the cover 1a supports vertically movable. A spring 26 is attached to the bearing 22 on the side of the upper cover 1a of the bearing 22, and the bearing 22 is constantly pressed in the direction of the arrow b (toward the photosensitive drum 2). Due to the action of the spring 26, the charging roller 4 is always in contact with the photosensitive drum 2 at a constant pressure and a constant nip width.

Further, as shown in FIG. 3, a cleaning member 27 made of polyurethane sponge, felt or the like is attached in the direction opposite to the contact point of the charging roller 4 with the photosensitive drum 2 (the back side of the upper cover 1a). In the normal use state, the charging roller 4 and the cleaning member 27 are separated from each other.

Next, a mechanism for separating the charging roller 4 from the photosensitive drum 2 and a cleaning mechanism will be described.

As shown in FIG. 4, gears 28 are provided on both sides (only one side is shown in FIG. 4) of the rotary shaft 20 of the charging roller 4, and are separated in a direction perpendicular to the axial direction of the rotary shaft 20. Each member 30 is provided. FIG. 5 is a view of FIG. 4 viewed from the same direction as FIG. The spacing member 30 has a narrow width in a portion in contact with the rotation shaft 20, and has a width that increases toward the left in FIG. Further, a rack 32 is provided above the separating member 30, and when the separating member 30 is slid, the rack 32 meshes with a gear 28 provided on the rotating shaft 20. Further, a knob 34 for operating the separating member 30 from the outside is provided. The knob 34 projects to the outside of the process unit 1 as shown in FIG.

The operation at the time of cleaning the charging device having the above configuration will be described.

When cleaning the charging roller 4, first, the process unit 1 is taken out from the apparatus main body. Next, the knob 34 is slid in the direction of arrow c in FIG. Then, as shown in FIG. 7, the rotating member 20 of the charging roller 4 is pushed up to the upper cover 1a side by the separating member 30, and the charging roller 4 and the cleaning member 27 come into contact with each other. When the knob 34 is further slid, the gear 28 provided on the rotating shaft 20 and the rack 32 provided on the separating member 30 mesh with each other, and the charging roller 4 rotates in the direction of arrow d in conjunction with the movement of the separating member 30. .. By this rotation operation, the cleaning member 27 cleans the entire surface of the charging roller 4. When the knob 34 reaches the right end, return it to the original left end. At this time, the charging roller 4 is cleaned while rotating in the opposite direction to that described above, and finally separated from the cleaning member 27 and again contacts the photosensitive drum 2. By performing the above operation once or several times, the foreign matter on the surface of the charging roller 4 can be completely wiped off.

As is clear from the above description, in the charging device of this embodiment, the charging roller 4 and the cleaning member 27 are separated from each other during normal use, so that the rotation torque can be suppressed to a low level, and the charging roller 4 can be kept low. The surface and the contact surface of the cleaning member 27 are not damaged by abrasion.

Further, since the charging roller 4 and the cleaning member 27 rotate in contact with each other in association with the operation of the separating member 30, the charging roller 4 can be automatically cleaned.

The present invention is not limited to the embodiments described in detail above, and modifications can be made without departing from the spirit of the invention.

[0027]

[Effect of the device]

 As is clear from the above description, in the charging device of the present invention, the charging member and the cleaning member are separated from each other during normal use and contact only during cleaning, so the rotational torque during normal use can be kept low. Therefore, the surface of the charging member and the contact surface of the cleaning member are not damaged by abrasion.

[Brief description of drawings]

FIG. 1 is a sectional view of a process unit.

FIG. 2 is a configuration diagram showing a pressure contact mechanism of a charging roller to a photosensitive drum.

FIG. 3 is an explanatory diagram showing a relationship between a charging roller and a cleaning member during normal use.

FIG. 4 is a perspective view showing a relationship between a charging roller and a separating member.

FIG. 5 is a side view showing a relationship between a charging roller and a separating member.

FIG. 6 is a perspective view of a process unit.

FIG. 7 is a side view showing an operation of separating the charging roller from the photosensitive drum.

FIG. 8 is a side view showing an operation of cleaning the charging roller.

[Explanation of symbols]

 2 photoconductor drum 4 charging roller 27 cleaning member 30 spacing member

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Soichiro Nishimura 15-1 Naeshiro-cho, Mizuho-ku, Nagoya-shi Brother Industrial Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. A charging device for charging or discharging a surface of an electrostatic latent image bearing member by bringing a charging member to which a voltage is applied from the outside into contact with the electrostatic latent image bearing member, for cleaning the surface of the charging member. A charging device comprising: a cleaning member; and a charging member moving unit that separates the charging member from the electrostatic latent image carrier and contacts the cleaning member.