JPH10198246A - Carrier cleaning device - Google Patents

Abstract

(57) [Problem] To efficiently remove a carrier of a two-component developer attached to a recording medium. An elastic member is rotated while being in contact with a recording medium, and a carrier attached to the recording medium is attracted to the elastic member by a magnetic force or a magnetic force and an electrostatic force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic recording apparatus, and more particularly to a carrier cleaning apparatus for removing a carrier adhered to a recording medium.

[0002]

2. Description of the Related Art Electrophotographic recording in which a toner is formed by applying a toner to an electrostatic latent image corresponding to image information formed on a recording medium by a developing device, and the toner image is transferred from the recording medium to recording paper. In the apparatus, a two-component developer composed of a toner and a magnetic carrier is widely used as a developer. In this developing method, the carrier may adhere to the recording medium during development, and the toner image around the adhered carrier is difficult to be transferred to recording paper, causing a problem of causing an image defect. In order to prevent this, a carrier cleaning device for removing a carrier attached to a recording medium is used. A conventional carrier cleaning device is mainly constituted by a cylindrical sleeve having a built-in columnar magnet, and is installed facing a recording medium with a small gap.

In recent years, a carrier having a small particle size has been used as a carrier for a two-component developer. However, since this carrier has a strong electrostatic force with a recording medium, a magnetic powder is dispersed in a resin. A carrier called a so-called resin carrier has a problem that it is difficult to be attracted to the carrier cleaning device due to a weak magnetic force.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a carrier cleaning apparatus having improved carrier collecting ability in view of the above circumstances.

[0005]

According to the present invention, in order to achieve the above object, the elastic member is rotated while contacting the recording medium to exert a mechanical force on the carrier, and the carrier adhered to the recording medium. And a magnetic force or a magnetic force and an electrostatic force are applied to the elastic member.

[0006]

FIG. 1 shows a first embodiment of the present invention. In the drawing, charging, exposure,
A toner image formed by the toner 2 positively charged by the developing process and an unnecessary carrier 3 negatively charged are attached. The carrier cleaning device 4 is provided so as to house the columnar stationary magnet 41, the magnet 41, and a cylindrical conductive sleeve 42, which rotates counterclockwise at substantially the same speed as the recording medium 1, and is mounted on the outer periphery of the sleeve 42. Covered elastic member 43, carrier 3 holding electric charge by frictional charging
A power supply 44 for applying a voltage to the sleeve 42 for electrostatically attracting the carrier 3, a scraper 45 for scraping the carrier 3 attached to the elastic member 43, and a collection container 46 for storing the scraped carrier 3. The sleeve 42 and the elastic member 43 are lightly pressed against the recording medium 1 by a pressing member such as a spring (not shown). The carrier 3 adsorbed on the surface of the elastic member 43 is scraped off by the scraper 45 and stored in the collection container 46. The collection efficiency is improved when the moving speed of the elastic member 43 is shifted by several percent from the moving speed of the recording medium 1 which is completely the same. This is presumably because a force that shifts the carrier 3 attached to the recording medium 1 in the lateral direction due to the speed difference acts to weaken the adhesion to the recording medium 1.
The elastic member 43 does not need to apply a strong pressure to the recording medium 1 and therefore only needs to be in light contact with the recording medium 1.

FIG. 2 shows a second embodiment of the present invention. The drawing differs from the first embodiment in that a thin sheet-like rubber magnet is used as the elastic member 43 instead of the columnar stationary magnet 41. According to the present embodiment, since the multi-polarized rubber magnet comes into direct contact with the carrier 3, a strong magnetic attraction force is exerted on the carrier 3 and the collection efficiency is increased.

FIG. 3 shows a third embodiment of the present invention. In the figure, a conductive sleeve 42 made of a non-magnetic material such as aluminum and an elastic member 43 are sequentially and integrally provided on the surface of a symmetrically magnetized magnet 41. They rotate integrally at substantially the same speed as the recording body 1 in the counterclockwise direction.
The sleeve 42 has a positive DC voltage 44 and an AC voltage 47
Are superimposed and applied. Electrostatically and magnetically elastic member 4
The carrier 3 adsorbed on the carrier 3 is stored in a collection container 46 by a scraper 45. According to the present embodiment, the carrier 3 receives the force of electrically oscillating by the AC voltage and the force of magnetically oscillating by the rotation of the magnet 41, thereby further increasing the recording medium 1.
This has the effect of increasing the efficiency of collection, making it easier to move away from the ground.

FIG. 4 shows a fourth embodiment of the present invention. In the figure, a symmetrically magnetized magnet 41 has an elastic member 43 on its surface, and rotates clockwise inside a nonmagnetic conductive sleeve 42 that rotates counterclockwise. A positive DC voltage 4 is applied to the sleeve 42 as in the third embodiment.
4 is applied with an AC voltage 47 superimposed thereon. The carrier 3 electrostatically and magnetically attracted to the elastic member 43 is stored in the collection container 46 by the scraper 45. According to this embodiment, similarly to the third embodiment, the carrier 3 receives the force of electrically oscillating by the AC voltage and the force of magnetically oscillating by the rotation of the magnet 41, and is further separated from the recording medium 1. This has the effect of increasing the collection efficiency.

As the elastic member used in the present invention, rubber materials such as urethane rubber and silicon rubber are suitable.
It is also preferable to use a rubber material whose surface is coated with a chemically inactive fluorine resin as a protective layer for contact with the recording medium and toner.

[0011]

As described above, according to the present invention, there is an effect that the carrier of the two-component developer adhered to the recording medium can be reliably removed.

[Brief description of the drawings]

FIG. 1 is a schematic side view of a carrier cleaning device according to an embodiment of the present invention.

FIG. 2 is a schematic side view of a carrier cleaning apparatus according to another embodiment of the present invention.

FIG. 3 is a schematic side view of a carrier cleaning apparatus showing still another embodiment of the present invention.

FIG. 4 is a schematic side view of a carrier cleaning device showing still another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Recording body, 2 ... Toner, 3 ... Carrier, 4 ... Carrier cleaning device, 41 ... Magnet, 43 ... Elastic member, 44
... DC voltage (power supply), 45 ... Scraper, 47 ... AC voltage (power supply)

Claims (3)

[Claims] 1. An electrophotographic recording apparatus for developing an electrostatic latent image formed on a recording medium with a two-component developer comprising a toner and a carrier, wherein the carrier attached to the recording medium is removed during development. In the carrier cleaning device, an elastic member that rotates while being in contact with the recording body;
A carrier cleaning apparatus, comprising: means for applying a magnetic field for adsorbing the carrier to the elastic member; and means for removing the carrier adsorbed on the elastic member from the elastic member. 2. A carrier cleaning apparatus according to claim 1, further comprising means for applying an electric field to said elastic member for electrostatically adsorbing said carrier. 3. The carrier cleaning apparatus according to claim 1, wherein the elastic member moves at a substantially same speed in a same direction as the recording body at a contact portion with the recording body.