JPH0256582A - Developing device - Google Patents

Abstract

PURPOSE:To obtain an image of uniform density having no sweep trace by arraying magnetic poles alternately in the axial direction of a developing sleeve opposite to a photosensitive body in the developing sleeve. CONSTITUTION:The developing magnetic poles 7 are arranged alternately in the axial direction of the developing sleeve. A developer which is agitated by an agitation blade 4 and conveyed onto the developing sleeve 2 is magnetized on the developing sleeve 2 by magnetic poles 6 and 7 in the developing sleeve 2. Then, the developing sleeve 2 rotates as shown b an arrow A to move the developer in the rotating direction of the developing sleeve 2 and when it is conveyed to the position opposite the photosensitive drum 1, the developer is carried to the photosensitive drum 1 to visualize an electrostatic latent image. In general, the developer forms a layer in the axial direction of the developing sleeve 2, but the developer is disordered in the axial direction of the developing sleeve 2 at the position opposite the photosensitive drum 1 by the developing magnetic poles 7 to obtain the uniform layer of the developer. Consequently, the excellent image of uniform image density having no sweep trace is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a developing device in an electrophotographic apparatus that uses a magnetic developer to visualize an electrostatic latent image.

(Prior Art) Generally, in an electrophotographic apparatus, a developing device containing a powder developer is installed on a part of the outer periphery of a photoreceptor drum, and the developer is attached to an electrostatic latent image formed on the photoreceptor drum. This makes it visible. There are two types of developer: magnetic developer and non-magnetic developer. In a developing device that uses magnetic developer, the developer is placed on a developing sleeve made of a rotatable non-magnetic plate, and is installed inside this developing sleeve. The electrostatic latent image on the photoreceptor is visualized by magnetizing the developer with the magnetic poles and forming a magnetic brush.

In such a developing device, the rotation of the developing sleeve causes
The developer magnetized on the developing sleeve moves in the rotational direction of the developing sleeve and is conveyed to a position facing the photoreceptor.

However, in such a developing device, a layer of developer is formed in the rotational direction of the developing sleeve, and a uniform layer of developer cannot be formed. For this reason, when an image is formed, there are problems such as streaks called "cross-cuts" appearing on the image and uneven image density.

(Problems to be Solved by the Invention) As detailed above, in a developing device using a magnetic developer, a layer of developer is formed in the rotational direction of the developing sleeve.
Problems such as smudges (called "bleaching") appearing on images and uneven image density occurred.

In the present invention, in order to solve the above problems, by forming a uniform layer of developer on the developing sleeve,
The objective was to obtain a good image with uniform developed density without any problems.

(Means for Solving the Problems) In order to solve the above problems, in the present invention, a plurality of magnetic poles are alternately arranged in the axial direction of the sleeve at positions facing the photoconductor in the developing sleeve. The developer layer formed in the rotational direction of the developing sleeve is disturbed in the axial direction of the developing sleeve to form a uniform developer layer, and as a result,
The aim was to obtain an image with uniform density without any blemishes.

(Function) By arranging a plurality of magnets in parallel in the axial direction inside the developing sleeve, the layer of developer is disturbed at the parts where the magnets touch each other, so that a uniform layer of developer is formed on the developing sleeve. Ru. As a result, a good image with uniform image density and no blemishes can be obtained.

(Example) Hereinafter, one example of the present invention will be described with reference to the drawings.

First, the structure of the apparatus used in this embodiment will be explained with reference to FIG. Reference numeral 1 in FIG. 1 is a photosensitive drum, on which an electrostatic latent image is formed. A rotatable developing sleeve 2 made of a non-magnetic material is installed at a position facing the photosensitive drum 1, a cutting plate 3 is placed at a position in contact with the developing sleeve 2, and a rotatable stirring blade 4 is placed above the developing sleeve 2. is installed. Further, inside the developing sleeve 2, a plurality of transport magnetic poles 6 are installed so that opposite magnetisms are placed next to each other, and a developing magnetic pole 7 is provided at a position facing the photoreceptor.
is installed. FIG. 2 shows the structure of this developing magnetic pole 7. The developing magnetic pole 7 has a structure in which a plurality of magnetic poles are arranged alternately in the axial direction of the developing sleeve.

Next, the operation of this developing device will be explained.

The developer stirred by the stirring blade 4 and conveyed onto the developing sleeve 2 is magnetized onto the developing sleeve by the magnetic pole within the developing sleeve 2 . When the developing sleeve rotates in the direction of arrow A, the developer moves in the rotational direction of the developing sleeve, and when it is conveyed to a position facing the photoreceptor drum 1, it is transferred to the photoreceptor drum 1 and becomes static. The electrolatent image becomes a visible image. The developer generally forms a layer in the axial direction of the developing sleeve, but at a position facing the photoreceptor drum, the developing magnetic pole 7
The developer is disturbed in the axial direction of the developing sleeve, resulting in a uniform developer layer.

As a result, when an image is formed, a good image with uniform image density and no "/% cutoff" can be obtained.

〔Effect of the invention〕

As detailed above, according to the present invention, the developer layer is disturbed by the action of the developing magnetic pole to form a uniform developer layer.
A good image with uniform image density and no blemishes can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the developing device of the present invention, and FIG.
FIG. 3, a schematic diagram showing the structure of a developing magnetic pole in one embodiment of the present invention, is a diagram showing another embodiment of the present invention. 6...Transportation reef 7...Developing magnetic pole agent Patent attorney Noriyuki Chika Right

Claims (1)

[Scope of Claims] A device main body having a collecting portion for collecting developer, a non-magnetic plate made of a rotatable non-magnetic material and forming a layer of developer on its surface, and an inner part of the non-magnetic plate. A plurality of transport magnetic poles having sequentially opposite polarities are installed along the circumferential surface, and a plurality of transport magnetic poles are arranged in the axial direction of the non-magnetic plate at positions facing the electrostatic latent image support on the inner circumferential surface of the non-magnetic plate. 1. A developing device comprising a developing magnetic pole formed by alternately arranging two magnets.