JPH08248770A - Developing device - Google Patents

Abstract

PURPOSE: To form a thin layer of a sufficient quantity of toner on a toner carrier over a long term by providing an auxiliary member for supplying toner which scrapes the toner remaining on a toner supplying member, without being supplied to the toner carrier. CONSTITUTION: A scraping plate 12 being the auxiliary member for supplying the toner is disposed in the press-contact part of a developing roller 2 with the toner supplying roller 3. The toner still carried on the toner supplying roller 3, without being supplied therefrom to the developing roller 2 is scraped by the part 14 of the scraping plate 12 and carried by the developing roller 2 through a path 10. Therefore, a sufficient quantity of toner can be supplied to the developing roller 2. Moreover, in the residual toner carried by the developing roller 2, after development is completed, the toner infiltrated into the press- contact part without being scraped by the toner supplying roller 3, in the entrance of the press-contact part with the toner supplying roller 3 is scraped by a part 15 and carried by the toner supplying roller 3 through a path 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a toner carrier for carrying a toner conveyed to a developing area, and a layer thickness regulating member for regulating the layer thickness of the toner on the carrier. The present invention relates to a developing device for visualizing a latent image formed on a latent image carrier by a toner after the layer thickness is regulated.

[0002]

2. Description of the Related Art It is well known in the prior art to use a developing device of the above type in an electrophotographic image forming apparatus such as a copying machine, a printer or a facsimile. Generally, in a developing device adopted in an image forming apparatus, a two-component developer containing a carrier and a toner, or a one-component developer containing no carrier (a developer consisting of toner particles only, or a toner flowing therein) Property, charge controllability, and cleaning properties of the residual toner on the latent image carrier, SiO ₂ , Si
A developer containing inorganic compound particles such as C or an auxiliary component such as zinc stearate) is used.

In this case, in particular, in a conventional developing device using a one-component developer (hereinafter, simply referred to as a toner if necessary), the amount of toner adhering to the toner carrier is insufficient and the toner is visibly visible. There is a possibility that the image quality of the image may deteriorate. In particular, when a non-magnetic toner which does not contain a ferromagnetic substance and does not contain a carrier made of a ferromagnetic substance is used in the composition constituting the toner particles, the toner is attached to the toner carrier by magnetic force. Therefore, it is particularly easy to cause a shortage of deposited toner.

Therefore, a toner supply member for positively supplying the toner to the toner carrier is provided, the toner is adhered to the toner carrier by the rotation of this member, and then the toner is regulated by the layer thickness regulating member. A developing device that regulates the layer thickness has been proposed.

[0005]

However, the amount of toner supplied to the toner carrier is not sufficient even by the developing device of the above-mentioned system, and the rotational speed of the toner carrier is changed to the rotational speed of the latent image carrier. If the same level is set, the final image density will be reduced. Therefore, conventionally, the rotational speed of the toner carrier is set to 3 to 4 times the rotational speed of the latent image carrier to artificially cover the insufficient amount of toner deposited on the toner carrier. , A toner in which the density of the trailing edge portion of an image becomes high when a so-called solid portion which is an entire surface image is developed.
The phenomenon of being from the rear end was occurring.

The present invention has been made in view of the above problems, and an object of the present invention is to form a sufficient amount of a thin toner layer on a toner carrier for a long period of time. Is to

[0007]

As a result of intensive studies, the inventors of the present invention have found that the toner supply member is deficient in toner supply amount due to the toner supply member. A considerable amount of toner among the toner transported to the pressure contact part with
It has been found that the above-mentioned phenomenon is not supplied to the toner carrier and passes through the pressure contact portion while being carried by the toner supply member, and the present invention has been completed.

That is, according to the present invention, a toner carrier for moving the toner carrying surface to convey the toner to the developing area, and the toner carrier arranged in pressure contact with the toner carrier. Of the toner carrier whose surface moves in the direction opposite to the toner carrier at the pressure contact portion, and the toner carrier of the toner carrier than the pressure contact position of the toner carrier. A latent image is formed by the toner after the layer thickness is regulated, which has a layer thickness regulating member which is disposed at a position downstream of the toner carrier in the direction of movement so as to face the toner carrier and regulates the toner layer thickness on the toner carrier. In a developing device for visualizing a latent image formed on a carrier, in the pressure contact portion between the toner carrier and the toner supply member, the toner left unsupplied on the toner carrier is left. Toner scraping off the toner on the supply member
A developing device having a supply assisting member is provided.

Further, in the developing device, the toner
The developing device is provided in which the supply assisting member is a thin plate.

In the developing device, the toner
There is provided a developing device in which two longitudinal end faces of the supply assisting member are disposed in the pressure contact portion between the toner supply member and the toner carrier.

In the developing device, the toner
One of the longitudinal end faces of the supply assisting member projects from the press contact portion to the upstream side in the moving direction of the toner carrier, and the toner
Provided is a developing device arranged in pressure contact with a carrier.

In the developing device, the toner
The supply auxiliary member is made of a conductive material, and a developing device to which an alternating voltage is applied is provided.

[0013]

According to the present invention, the toner conveyed to the pressure contact portion between the toner carrier and the toner supply member by the toner supply member is scraped off from the toner supply member by the toner supply auxiliary member. It is supplied to the toner carrier. Therefore, the toner
In the toner conveyed by the supply member to the pressure contact portion between the toner carrier and the toner supply member, less toner passes through the pressure contact portion without being supplied to the toner carrier, and the toner carrier is reduced. Toner supply rate to

Further, according to the present invention, the toner carried on the toner carrying member is satisfactorily removed after the development is completed.

Further, according to the present invention, the frictional charging of the toner by the pressure contact between the toner carrier and the toner supply member is not impaired, and the toner is favorably charged.

Further, according to the present invention, it is possible to make the width of the toner supply assisting member sufficiently long.

According to the present invention, the mobility of the toner on the toner carrier and the toner on the toner supply member is increased, and the toner on the toner carrier and the toner on the toner supply member are increased. The toner is scraped off well.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

First, a first embodiment of the present invention will be described with reference to FIGS.
Will be explained. First, FIG. 1 is a sectional view showing a main part of an image forming apparatus to which the developing device of this embodiment can be applied.
In FIG. 1, a photoreceptor 1 which is a latent image carrier having an electrostatic latent image formed on its surface through a conventionally known image forming process.
In contrast, the toner carrier has elasticity and has a toner on the surface.
The developing roller 2 having a thin layer formed thereon is brought into contact with the toner through a toner to perform development. Here, the toner thin layer is formed on the developing roller 2 as follows. First, the toner 4 stored in the storage unit is rotated by the toner supply roller 3 having elasticity, which is a toner supply member, in the direction of the arrow in the drawing, and the developing roller 2 and the toner supply roller 3 are rotated. It is transported to the pressure contact part with. Then, the toner conveyed to the above-mentioned pressure contact portion is triboelectrically charged from the developing roller 2 and the toner supplying roller 3 and adheres to the developing roller 2 by an image force to be a thin layer thickness regulating member. The layered blade 5 is conveyed to the pressure contact portion and is subjected to the layer thinning action. The developing layer thinned in this way is
The toner on the roller 2 is conveyed to a portion where the photoconductor 1 and the developing roller 2 face each other, and is provided for development. On the other hand, after the development, the toner remains on the surface of the developing roller 2 corresponding to the non-image portion of the latent image and causes an afterimage, so this residual toner needs to be removed. -Supply roller 3 is developing roller 2
The toner supply roller 3 rotates in the same direction and moves in opposite directions at the opposite portions, so that the toner supply roller 3 remains on the developing roller 2.
It also has the function of scraping off.

In the developing device having such a structure, however, a part of the toner supplied to the pressure contact portion between the developing roller 2 and the toner supplying roller 3 is part of the toner supplying roller 3. The image is not supplied to the developing roller 2 due to a mirror image force or the like and passes through the pressure contact portion. If such a large amount of toner passes through, the toner supply efficiency to the developing roller 2 becomes low, and the toner carrying amount of the developing roller 2 generally held by the one-component developing device. Cause low. Regarding the scraping of the residual toner on the developing roller 2 after the completion of development, a part of the toner conveyed to the pressure contact portion is also scraped off by the scraping action of the toner supply roller 3. Without passing through the pressure contact portion, it causes an afterimage.
As described above, in order to increase the capacity of the toner supply and the scraping of the toner in order to cope with the insufficient capacity, the developing roller 2, the toner supplying roller 3, and the toner-4 are used.
Since the material, structure, etc. are limited, the cost becomes high.

Therefore, in the present invention, as shown in FIG. 2, a scraping plate 12 as a toner supply assisting member is arranged at the pressure contact portion between the developing roller 2 and the toner supply roller 3. The scraping plate 12 is a thin plate made of a conductive material such as stainless steel or steel. The scraping plate 12 does not impair the triboelectrification effect on the toner due to the pressure contact between the developing roller 2 and the toner supplying roller 3. It is preferable that the width is smaller than the pressure contact nip width of the roller 2 and the toner supply roller 3.

Here, the scraping plate 1 in FIG. 2 is shown in FIG.
2 is an enlarged view of a peripheral portion (circle portion in FIG. 2) of FIG. The toner is not supplied to the developing roller 2 from the toner supplying roller 3
The toner still carried on the supply roller 3 is the scraping plate 1
Toner scraped off and scraped off at 14 in FIG.
Is conveyed by the developing roller 2 through a path 10 in the drawing. Therefore, a sufficient amount of toner can be supplied to the developing roller 2. In addition, after the development is completed, the residual toner carried by the developing roller 2 is not scraped off by the toner supplying roller 3 at the inlet of the pressure contacting portion with the toner supplying roller 3 and enters the pressure contacting portion. The residual toner that has entered is scraped off at the portion 15 of the scraping plate 12 in the drawing, and the scraped toner is 1 in the drawing.
It is conveyed by the toner supply roller 3 through the path 1. Therefore, the toner thin layer on the developing roller 2 becomes a uniform toner thin layer, and the portion moved to the side of the electrostatic latent image bearing member during the development is subjected to the toner layer thickness or charging until the next development. It is possible to prevent an image defect called a sleeve ghost which occurs because the amount and the like do not recover to the same condition as other portions. still,
In the present embodiment, in order to efficiently perform the scraping action by the scraping plate 12 as described above, edges 14 and 15 in the figure of the scraping plate 12 are subjected to edge processing. Further, since an alternating voltage is applied to the scraping plate 12 by the power source 13, the mobility of the toner is improved and the scraping efficiency is increased.

Next, a second embodiment of the present invention is shown in FIG. The second embodiment differs from the first embodiment only in the width and the disposition position of the scraping plate 20. That is, one end of the scraping plate 20 is located in the pressure contact portion between the developing roller 2 and the toner supply roller 3 as in the first embodiment, but the other end is from the pressure contact portion to the developing roller. The roller 2 protrudes toward the upstream side in the rotation direction of the roller 2 and is pressed against the developing roller 2. In this way, the scraping of the residual toner after the development on the developing roller 2 cannot be performed by the effect of the toner supply roller 3, but the scraping is not caused due to the characteristics of each member. Scraping plate 20
In many cases, the action of is sufficient. Therefore, in such a case, the width of the scraping plate 20 can be made sufficiently wide by adopting the configuration shown in the second embodiment, and the deformation and bending of the scraping plate 20 can be prevented and the reliability can be improved. Is improved.

[0024]

As described above, according to the present invention, the toner conveyed by the toner supplying member to the pressure contact portion between the toner carrier and the toner supplying member is the toner supplying auxiliary member. -Scraped from the supply member and supplied to the toner carrier. Therefore, in the toner conveyed by the toner supply member to the pressure contact portion between the toner carrier and the toner supply member, less toner passes through the pressure contact portion without being supplied to the toner carrier, The toner supply rate to the toner carrier increases. Therefore, a sufficient amount of thin toner layer can be formed on the toner carrier for a long period of time.

Further, according to the present invention, since the toner carried on the toner carrier is favorably removed after the development is completed, it is possible to form a uniform thin toner layer on the toner carrier. it can.

Further, according to the present invention, the frictional electrification of the toner due to the pressure contact between the toner carrier and the toner supply member can be favorably carried out. Therefore, a sufficiently charged thin toner layer can be formed on the toner carrier.

Further, according to the present invention, the width of the toner supply assisting member can be made sufficiently long. Therefore, it is possible to provide a developing device with improved reliability by preventing the toner supply auxiliary member from being deformed or bent.

According to the present invention, the mobility of the toner on the toner carrier and the toner on the toner supply member is increased, and the toner on the toner carrier and the toner supply member on the toner carrier are increased. The toner is scraped off well. Therefore, a sufficient amount of a thin toner layer can be formed on the toner carrier for a long time, and a uniform toner layer can be formed on the toner carrier.
Thin layers can be formed.

[Brief description of drawings]

FIG. 1 is a main part configuration diagram showing an image forming apparatus to which a developing device of the present invention can be applied.

FIG. 2 is a main part configuration diagram showing a first embodiment of the present invention.

FIG. 3 is an enlarged view of a main part configuration showing a first embodiment of the present invention.

FIG. 4 is a main part configuration diagram showing a second embodiment of the present invention.

[Explanation of symbols]

 1 Photoreceptor 2 Developing Roller 3 Toner Supply Roller 4 Toner 5 Thinning Blade 12, 20 Scraping Plate 13 Power Supply

Claims (5)

[Claims] 1. A toner carrier for transporting the toner to a developing area by moving a surface carrying the toner, and a toner carrier which is disposed in pressure contact with the toner carrier and supplies the toner to the toner carrier. The surface of the member is the toner at the press-contact portion.
A toner supply member that moves in the opposite direction to the carrier, and a toner supply member facing the toner carrier at a position downstream of the pressure contact position of the toner supply member in the moving direction of the toner carrier. A toner on a carrier, a layer thickness regulating member for regulating a layer thickness, and a developing device for visualizing a latent image formed on a latent image carrier by the toner after the layer thickness is regulated. A toner supply auxiliary member for scraping off the toner on the toner supply member left unsupplied on the toner carrier in the pressure contact portion between the carrier and the toner supply member. Developing device. 2. The developing device according to claim 1, wherein the toner supply auxiliary member is a thin plate. 3. The developing device according to claim 2, wherein both end faces in the longitudinal direction of the toner supply assisting member are disposed in the pressure contact portion between the toner supply member and the toner carrier. Developing device. 4. The developing device according to claim 2, wherein one surface of an end surface in the longitudinal direction of the toner supply assisting member projects from the pressure contact portion to the upstream side in the moving direction of the toner carrier. A developing device, which is arranged in pressure contact with a carrier. 5. The developing device according to claim 1, wherein the toner supply auxiliary member is made of a conductive material, and an alternating voltage is applied.