JPH0784449A - Developing device - Google Patents

Abstract

PURPOSE:To surely scrape a developer remaining on a developing roller. CONSTITUTION:In this developing device provided with a developer supplying roller 4 rotated in such a manner that it is abutted on the developing roller, to supply the developer thereto and simultaneously, functioning to scrape the developer left on the developing roller, without being supplied to a photosensitive body and returned, a reciprocating mechanism composed of a cam member 18, a projecting member 17 and a spring member 19, for reciprocating the developer supplying roller 4 in its axial direction is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for developing a latent image by supplying a developer onto an image carrier, and a copying machine, a printer device, or an electrophotographic process for forming an image. Used in facsimile machines and the like.

[0002]

2. Description of the Related Art A conventional developing device is provided with, for example, a developing roller, a developer supplying roller, a blade member, and an agitator in a developer box. The developer in the developer box is the agitator. To the developer supply roller and from the developer supply roller to the development roller, and the developer on the development roller is regulated in a thin layer by the blade member and onto the photosensitive drum as the image carrier. Supplied with.

The developer that has not been supplied onto the photosensitive drum during development (hereinafter referred to as residual developer) is
It is returned to the inside of the developer box by the rotation of the developing roller, scraped off by the developer supply roller rotating in contact with the developing roller, and collected in the box (see JP-A-63-52166).

[0004]

However, the conventional developing device described above does not have sufficient ability to scrape off the residual developer. If the residual developer is not sufficiently scraped off, the residual developer that has not been scraped off adheres to the developing roller, and the thickness of the developer thin layer and the charge amount become non-uniform, which deteriorates the image quality. there were. In particular, when the print pattern in which the developer at the same position on the developing roller is supplied to the photosensitive drum is repeated, the sticking of the residual developer is more likely to occur.

In view of the above circumstances, it is an object of the present invention to provide a developing device capable of surely scraping off the residual developer on the developing roller to prevent it from sticking, and performing good development.

[0006]

In order to solve the above-mentioned problems, the developing device of the present invention supplies the developer to the developing roller and the image bearing member by rotating while contacting the developing roller. In a developing device equipped with a developer supply roller that functions to scrape off the developer remaining on the development roller and returned to the developer box, the developer supply roller is reciprocated in the axial direction. It is characterized in that a reciprocating mechanism for moving is provided.

[0007]

According to the above structure, the residual developer on the developing roller is scraped off by both the rotation and the axial reciprocating motion of the developer supply roller, so that the residual developer is reliably removed. That is, a force obtained by adding the rotational force and the reciprocating force acts on the residual developer as a scraping force, and the action direction thereof is sequentially changed by the reciprocating movement of the developer supply roller. It is possible to surely scrape off the residual developer that is not removed, or even the residual developer that is not sufficiently scraped off from only one direction. As a result, it is possible to prevent the residual developer from sticking to the developing roller, obtain a stable and appropriate amount of charge, and form a good image without unevenness.

[0008]

【Example】

(Embodiment 1) The present invention will be described below with reference to the drawings showing the embodiment.

FIG. 1 is a side sectional view showing an electrophotographic process mechanism section. Reference numeral 5 in the figure denotes a photoconductor as an image carrier, and around the photoconductor 5 along the rotation direction thereof,
The charging device 10, the exposure device 7, the developing device 1, the transfer device 8, and the cleaning device 12 are arranged in this order.

When the charging device 10 uniformly applies positive or negative charges to the photoconductor 5 and the exposure device 7 performs light irradiation based on image information, the photoconductor 5 receives the light irradiation. The charges of the portion are removed and an electrostatic latent image is formed on the surface of the photoconductor 5.

Then, the developer 2 is supplied to the electrostatic latent image on the photoconductor 5 from the developing device 1, so that the developer 2 is attached to the latent image portion, and an image is formed by the developer 2. The image formed by the developer 2 is transferred onto a sheet by the transfer unit 8, and the sheet is discharged to the outside of the apparatus through the fixing unit.

On the other hand, the developer 2 remaining on the photosensitive member 5 without being transferred is scraped off by the cleaning blade 9 of the cleaning device 12 and collected as waste toner in the cleaning device 12.

The above-mentioned developing device 1 includes a developer box 11 for containing the developer 2 and an agitator 1 for stirring the developer 2.
3, a developing roller 3 for supplying the developer 2 onto the photoconductor 5,
The developer supplying roller 4 for supplying the developer 2 to the developing roller 3 and the developer 2 on the developing roller 3 are brought into contact with each other to regulate the thickness thereof to a constant value, and the friction at that time imparts an electric charge to the developer 2. The blade member 6 and the developer leakage prevention member 14 are provided.

FIG. 2 is a side sectional view showing the developing portion in FIG. 1 in an enlarged manner. The developing device 1 is biased toward the photoconductor 5 by a pressing unit (not shown), and the developing roller 3 is pressed against the photoconductor 5 by this biasing. As the material forming the developing roller 3, when a negatively charged (-) developer 2 is used, a material more positive in the triboelectric charging series than the developer 2, for example, an elastic body such as urethane rubber is used. To be

The developing roller 3 is provided so as to rotate counterclockwise in the figure by a drive mechanism (not shown).
Further, the developer supply roller 4 is also provided so as to rotate counterclockwise in the figure, but is further adapted to reciprocate in the axial direction thereof as described later. And both rollers 3 and 4 contact each other's peripheral surface,
The contact surfaces are rubbed together by the rotation of both rollers 3 and 4 and the reciprocating movement of the developer supply roller 4.

The developer 2 flows above the contact surfaces of the rollers 3 and 4 and is triboelectrically charged with the developing roller 3 to be adsorbed on the surface of the developing roller 3. The developer 2 adsorbed on the developing roller 3 is conveyed to a position facing the photoconductor 5 by the counterclockwise rotation of the developing roller 3 and supplied to the latent image portion of the photoconductor 5. Development is performed by.

On the other hand, the developer not supplied onto the photoconductor 5 during the development (hereinafter, referred to as residual developer) is returned to the developer box 11 again by the counterclockwise rotation of the developing roller 3 and developed. It is scraped off by the developer supply roller 4 that rotates while reciprocating while being in contact with the roller 3, and is collected in the box 11.

FIG. 3 is a front view showing a mechanism for reciprocating the developer supply roller 4 in its axial direction. 2 in the figure
A bearing portion 5 fixed to the developing device 1 supports the shaft 4a of the developer supply roller 4 rotatably and slidably in the axial direction. A rotary gear 20 is fixed to one end of the shaft 4a.
Driving force is transmitted from a motor (not shown). Of course, even if the developer supply roller 4 reciprocates in the axial direction, the transmission of the driving force to the rotary gear 20 is ensured.

A cam member 18 is fixed to the other end of the shaft 4a and outside the bearing portion 25. The distance between the cam member 18 and the bearing portion 25 is set to be equal to or longer than the distance corresponding to the reciprocating section of the developer supply roller 4.

The cam member 18 has a cam surface 18a formed on the outer surface thereof so as to be oblique to the vertical cross section of the shaft 4a. The angle θ formed by the cam surface 18a and the vertical cross section of the shaft 4a is set to 0 ° <θ <90 °.

The projection member 17 is in contact with the cam surface 18a. The protruding member 17 is fixed to the developing device 1. On the other hand, the spring member 19 is in contact with the end surface on the one end side of the shaft 4a, and the urging force of the spring member 19 constantly maintains the contact between the protruding member 17 and the cam surface 18a. The spring member 19 is fixed to the side surface of the device body.

With such a configuration, the relative position of the developer supply roller 4 with respect to the projecting member 17 periodically changes in the axial direction by the rotation of the developer supply roller 4, and the developer supply roller 4 rotates in the axial direction. It reciprocates and rubs against the developing roller 3.

The residual developer on the developing roller 3 is surely scraped off due to the rubbing of the rollers 3 and 4 due to both the rotational and axial reciprocating motions. That is, the force obtained by adding the rotational force and the reciprocating force acts on the residual developer as a scraping force, and
Since the action direction thereof is sequentially changed by the reciprocating movement of the roller 4, the residual developer which is not sufficiently scraped off only by the rotational force or the residual developer which is not sufficiently scraped off only from one direction is surely scraped off. Become.

(Embodiment 2) Another embodiment of the present invention will be described below with reference to FIG.

In the developing device of this embodiment, while the developing device of the above-described embodiment 1 always secures the contact between the projection member 17 and the cam member 18 by the spring member 19, the cam member 18 '. The guide groove 18'a formed in the above ensures that the cam member 18 'and the projection member 17 are always in contact with each other.

The guide groove 18'a is formed in the first embodiment.
Corresponding to the cam surface 18a of the cam member 18 of
The inclination θ of the guide groove 18′a with respect to the vertical cross section of the shaft 4a is set to 0 ° <θ <90 ° as in the first embodiment.

As a result, as in the first embodiment, the reciprocating motion in the axial direction is applied to the developer supplying roller 4, whereby the residual developer on the developing roller 3 is surely scraped off.

[0028]

As described above, according to the present invention, since the developer supplying roller axially reciprocates, the residual developer on the developing roller is surely scraped off. It is possible to form a good image without unevenness by preventing the toner from sticking to the surface, obtaining a stable and appropriate amount of charge.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an electrophotographic process mechanism section.

FIG. 2 is a side sectional view showing a developing portion in FIG. 1 in an enlarged manner.

FIG. 3 is a front view showing a developing supply roller driving portion of the developing device of the present invention.

FIG. 4 is a front view showing a developing supply roller driving portion of a developing device in another embodiment of the present invention.

[Description of Reference Signs] 1 developing device 3 developing roller 4 developer supply roller 17 projecting member 18 cam member 18 'cam member

Claims (1)

[Claims] 1. A developer that is supplied to the developing roller by being brought into contact with the developing roller and being rotated and is not supplied to the image bearing member but left on the developing roller and returned to the inside of the developer box. In a developing device having a developer supply roller that functions to scrape off the developer, a reciprocating mechanism for reciprocating the developer supply roller in the axial direction is provided.