JPS59129882A - Developing device - Google Patents

Abstract

PURPOSE:To execute the stirring of a toner, and to prevent the generation of disorder of a picture due to the flocculation of the toner, etc. by providing a magnetic pole inside by which a repulsion magnetic field is generated between a control doctor on a developing sleeve and a developing area. CONSTITUTION:A magnet 6 by which a repulsion magnetic field is generated between a doctor blade 5 and the developing area of a photosensitive body 1 is provided in a developing sleeve 2. A toner whose layer thickness is controlled by the blade 5 and which is coated on the sleeve 2 becomes a napping state on a magnetic pole 6-2, but since the magnetic poles 6-2, 6-3 are repulsion magnetic poles, the napping length becomes longer than the usual napping. Subsequently, when the toner moves to the magnetic pole 6-3, it moves so as to jump, and during this time, the toner is stirred, and the flocculation is loosened. Therefore, the developer is stirred sufficiently, and the generation of disorder of a picture due to a flocculated toner can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing device used in an image forming apparatus such as an electrophotographic copying machine, and particularly relates to a developing device using a magnetic developer.

A developing device using a magnetic developer generally uses a rotatable developer carrier, such as a non-magnetic sleeve, which has a magnet fixed therein as a magnetic field generating means, and coats the developer onto the sleeve to form a latent image. Obtain a microscopic image by facing the surface. - In one method using a magnetic developer, an insulating magnetic toner is coated in a thin layer on a sleeve which is rotated by a magnetic blade, and an alternating voltage is applied in the development area to create an electrostatic charge between the sleeve and the electrostatic developer. A developing method in which toner is moved back and forth between the latent image surface and the latent image surface is disclosed in Japanese Patent Laid-Open No. 55-1.
8858-9. In addition, using a developer containing a mixture of a fine resin-coated magnetic carrier with the same particle size as the toner and a non-magnetic high-resistance toner, the rotation of the sleeve So-called microtoning development, which involves rubbing the electrostatic latent image surface, is also known. In either case, developer is applied onto the sleeve by a developer regulating member called a magnetic or non-magnetic doctor blade. Hopper If you collect one-component toner inside and regulate it with a doctor blade, it will be removed when the developer is left for a long time.
Otherwise, the toner aggregates in the hopper due to toner agitation, and the toner also sticks to the sleeve.

This passes between the plate and the sleeve and disturbs the image, causes background smudges on the image, or in some cases gets stuck between the sleeve and the latent image carrier.

An object of the present invention is to provide a developing device which eliminates the above-mentioned drawbacks and is improved so that the effects of toner aggregation and the like do not appear on images.

The present invention is a developing device in which a repulsive magnetic field is formed after applying a magnetic developer to a developer carrier until reaching a developing area.

Hereinafter, the present invention will be explained in detail based on the drawings.

In FIG. 1, reference numeral 1 denotes a photosensitive plate as a latent image carrier which rotates in the direction of arrow A, and has an electrostatic image formed on its surface. 2 is a sleeve made of a non-magnetic material such as stainless steel or aluminum, and has a magnet 6 fixed therein;
Rotate in the direction of arrow B. Reference numeral 3 denotes a hopper for storing magnetic toner, which has a rotating rod 4 for stirring the toner inside, and the rotating rod 4 rotates in the direction of arrow C to prevent the toner from agglomerating. Here, reference numeral 5 denotes a doctor blade made of a magnetic material such as iron, which is disposed facing one fixed magnetic pole 6-1 of the magnet 6, regulates the layer/thickness of the magnetic toner by magnetic force, and controls the layer/thickness of the magnetic toner. The second layer is coated with a thin layer of toner. The toner coated on the sleeve is 6-2.
It passes through the repelling magnetic pole S-8 shown at 6-3, where the toner layer is disturbed and re-coated. That is, the single layer of toner first stands on top of the magnetic pole 6-2. Here 6-
Since 2 and 6-3 are repulsive magnetic poles, the length of the panicle is longer than that in the normal panicle stand state. Next, the toner moves to the 6-3 pole. At this time, the toner jumps from the 6-2 pole to the 6-3 pole, and during this time, the toner is disturbed and the aggregated toner is loosened. The toner loosened in this way is conveyed to the 6-4 poles, which are development poles, and is subjected to development in the development area. The other magnetic pole is a magnetic pole for toner transport. During development, an alternating current voltage may be applied between the sleeve 2 and the photosensitive plate 1 by the power source 7, and the toner may be moved back and forth between the photosensitive plate and the sleeve to perform the development.

FIG. 2 shows another embodiment of the invention. 1 is an electrostatic latent image carrier, and 2 is a non-magnetic sleeve that moves in the directions of arrows A and B, respectively. The hopper 3 stores a developer consisting of a fine carrier made of a magnetic material such as magnetite coated with a resin and a toner mainly made of an insulating resin. 8 is a doctor blade made of a non-magnetic material such as aluminum, and the developer in the hopper is transferred to the sleeve 2.
It passes through the doctor blade 8 due to the rotational force of the magnetic field generating means 9 and the magnetic force of the magnetic pole 9-1 of the magnetic field generating means 9, and is coated on the sleeve. Here, the magnetic pole 9-1 is configured as a repelling magnetic pole, and when the developer moves to the other pole 9-2, the developer is disturbed as described above and the agglomeration is loosened. The agitated developer reaches the development pole 9-3 and is transferred to the development pole 9-3.
The electrostatic latent image carrier 1 is rubbed against the electrostatic latent image carrier 1, and the latent image is visualized.

As described above, in the present invention, by providing repulsive magnetic poles between the developer layer regulating member and the development area, the magnetic developer is stirred and image disturbances caused by agglomerated toner are prevented, and image disturbances are always maintained. A good image can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a developing device showing an embodiment of the present invention, and FIG.
The figure is a sectional view of another embodiment of the invention. In the figure, 1 is a latent image carrier, 2 is a sleeve, 5.8 is a doctor blade, 6 is a magnet, and 7 is an AC power source. Criminal: Canon Co., Ltd.

Claims (1)

[Claims] A developer carrier disposed opposite the latent image carrier in the development area, a magnetic field generating means fixed within the developer carrier, and regulating the layer thickness of the magnetic developer on the developer carrier. 1. A developing device, wherein the magnetic field generating means has a repulsive magnetic field from after the layer thickness of the magnetic developer is regulated to when the developing area is reached.