JPH055111B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a developing device, and more specifically,
It relates to a wet developing device.

(Prior Art) An electronic copying machine is equipped with a developing device for visualizing an electrostatic latent image carried on a photoreceptor, and a typical example is a developing device that uses a liquid developer. There is a wet developing device used.

As a wet type developing device, a multi-stage developing device is known in which a plurality of stages of developing sections are provided along the moving direction of a photoreceptor surface serving as an electrostatic latent image bearing surface.

This multi-stage developing device has, for example, a plurality of stages of developing rollers for supplying developer disposed near the photoreceptor drum along the rotational direction of the drum, thereby controlling the contact area between the developer and the electrostatic latent image. The aim is to expand development efficiency and improve development efficiency.

By the way, in such a multi-stage developing device, especially in a developing device using a developing roller, new developer is normally supplied to the surface of the photoreceptor by the developing roller in the later stage, but in reality, new developer is supplied to the surface of the photoreceptor. When the developer supplied from the developing roller and which has consumed the toner particles remains on the surface of the photoreceptor as it moves, and this photoreceptor surface is the drum surface, As the surface tangles with movement, the developer supplied by the subsequent developing roller only comes into contact with the remaining developer, and is not given an opportunity to contact the electrostatic latent image on the photoreceptor surface. Even if a new developer was supplied from a downstream developing roller, it was not possible to improve the development efficiency with the new developer.

(Objective) The present invention has been made in view of the above, and an object of the present invention is to provide a developing device that eliminates the above-mentioned drawbacks.

(Structure) The present invention provides a developing device in which a plurality of stages of developing sections are arranged along the moving direction of a photoreceptor surface, in which residual developer on the photoreceptor surface is removed between the developing sections, and a subsequent developing section The feature is that a new developer is supplied again.

The present invention will be explained below with reference to illustrated embodiments.

In FIG. 1, numeral 1 is a photosensitive drum;
is the first developing roller, 3 is the second developing roller, and 4 is the second developing roller.
5 indicates a stirring roller, and 5 indicates an excess liquid removal roller, respectively.

The photosensitive drum 1 is rotatable in the direction indicated by an arrow A in the figure by a rotation drive section (not shown).

On the other hand, each of the first and second developing rollers 2 and 3 has a gap between them and the surface of the photoreceptor drum set to 75 to 100 μm, and the developing portions are arranged in multiple stages along the rotating direction of the photoreceptor drum 1. It is rotatably driven in the direction shown by arrow B in the figure.

In the vicinity of each of the first and second developing rollers, there is a developer supply section 6 introduced from a developer tank (not shown).
Further, a developer reservoir section 7 is provided, in which the developer supplied from the supply section 6 is stored, and a part of the circumferential surface of the first and second developing rollers 2, 3 is immersed in the reservoir section. ing.

The stirring roller 4 is disposed between the first and second developing rollers 2 and 3 along the rotating direction of the photosensitive drum 1, with a gap between the stirring roller 4 and the photosensitive drum 1 being set to 50 μm.

The stirring roller 4 is driven to rotate in a direction opposite to the rotation direction of the photoreceptor drum 1, as shown by an arrow C in the figure, and a developer scraping member 8 is applied to a part of the circumferential surface of the stirring roller 4. are in contact with each other.

The stirring roller 4 is rotated in the first direction depending on its direction of rotation.
This is for removing the developer supplied from the developing roller 2 and in which the toner has been consumed from the surface of the photoreceptor drum.

The surplus liquid removing roller 5 is disposed at the final position of the developing section, is driven in a direction opposite to the rotating direction of the photoreceptor drum 1, and is used to scrape off excess developer remaining on the surface of the photoreceptor drum before transfer. Remove by.

A scraper 9 is attached to the circumferential surface of the surplus liquid removal roller 5 for scraping off the surplus developer removed from the surface of the photoreceptor drum.

Note that the gap between the surplus liquid removing roller 5 and the drum surface is set to 50 μm to increase the liquid removal efficiency.

In the developing device having the above configuration, the remaining developer supplied from the first developing roller 2 and traveling around the photoreceptor drum 1 after toner particles are consumed is distributed between the developing roller, the stirring roller 4, and the drum surface. Utilizing the difference between Then, new developer is supplied to the surface of the photoreceptor drum again.

Further, when the stirring roller 4 removes the developer remaining on the drum surface from the surface, it agitates the developer, so that the toner particles are dispersed in the remaining developer and the toner particles are transferred to the surface of the drum. Move toward the electrostatic latent image.

Therefore, the stirring roller 4 not only removes the developer, but also contributes to the development during the removal, albeit for a short time. Therefore, the development efficiency may be increased by applying a development bias to the stirring roller that mechanically removes the developer.

In the above-described embodiment, the rotation directions of the first and second developing rollers 2 and 3 are set so that their moving directions in the vicinity of the photosensitive drum 1 are the same. The rotation setting is not limited to this, but the rotation setting may be made in the opposite direction to the rotation direction of the photoreceptor drum 1, as shown in FIG.

(Effects) According to the present invention, when multi-stage development is performed, the so-called old developer that has been supplied by the first-stage development section and has consumed toner particles is removed from the surface of the single-layer photoreceptor, so that the second-stage development Fresh developer supplied from the section can be brought into contact with the surface of the photoreceptor. This makes it possible to develop the latent image with new developer during multi-stage development. The ratio between the amount of developer supplied and the content of toner particles in the developer can be increased.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, and FIG. 2 is a schematic diagram showing a modification of the main part of the embodiment of the present invention. 1...Photosensitive drum, 2, 3...Developing roller,
4... Stirring roller.

Claims (1)

[Scope of Claims] 1. A developing device comprising a wet developing section including at least a first and a second developing roller along the moving direction of a photoreceptor carrying an electrostatic latent image, The first and second developing rollers and the removing member are arranged between the developing rollers and remove the remaining developer after toner has been consumed on the photoreceptor, and the first and second developing rollers and the removing member A developing device characterized in that the developing device is arranged with a predetermined distance. 2. The developing device according to claim 1, wherein the member for removing residual developer is a rotatable roller. 3. The developing device according to claim 1, wherein the member for removing residual developer is driven to move in a direction opposite to the moving direction of the photoreceptor.