JPS6289976A - Electrostatic latent image developing device - Google Patents

Abstract

PURPOSE:To prevent a toner from being solidified in a replenishing device by providing a rotating member, which removes the toner on a developing roller, between the developing roller and the side wall of the toner replenishing device. CONSTITUTION:A toner removing roller 16 consists of a metal or conductive rubber and is provided between the upstream side wall of a hopper 4 in the rotation direction of a developing roller and the developing roller 1, and a scraper 17 which scrapes the toner on the surface of the roller 16 is provided on the side wall above the removing roller 16. A DC bias power source 18 is connected between the developing roller 1 and the roller 16, and a bias voltage having a polarity opposite to that of the toner electrostatically charged by a charging plate 6 is applied to the roller 16. The roller 16 is always brought into contact with the roller 1 to attract electrostatically the remaining toner on the roll 1. The toner attracted to the surface of the roll 16 is scraped by the scraper 17 and is used again in the hopper as it is.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic latent image developing device for developing an electrostatic latent image formed on a photoreceptor by electrophotography using -component nonmagnetic toner.

First, an example of such a developing device to which the present invention is applied will be explained with reference to FIG. The developing roller 1 is for holding a one-component non-magnetic toner on its surface and bringing the second roller into contact with the electrostatic latent image on the photoreceptor 2 . This roller is made of conductive rubber, preferably silicone rubber. The photoreceptor 2 has selenium on a conductive support 2a.
Zinc oxide.

A photoconductive layer 2b such as cadmium oxide or polyvinyl carbazole is coated to form a sheet or belt.

It is formed into a drum shape. A bias power source 3 is connected between the developing roller 1 and the conductive support 2a of the photoreceptor 2. This is done by applying a potential to the developing roller 1 that is slightly higher than the surface potential of the non-image area of the electrostatic latent image formed on the photoreceptor.

This is to prevent toner from adhering to non-image areas. The hopper 4 accommodates -component non-magnetic toner 5,
This is for supplying this onto the developing roller 1.

The amount of Je supplied toner is regulated by the tip of the side wall 4a of the hopper in the direction of rotation of the developing roller. The charging plate 6 frictionally charges the toner supplied on the developing roller to a polarity opposite to that of the electrostatic image formed on the photoreceptor. Resin is used. These resins can charge the toner negatively or positively depending on whether they are higher or lower on the triboelectric charging series than the resin components constituting the toner. The toner on the developing roller is charged by the charging plate 6.

The static ffi latent image on the photoreceptor 2 is contacted and visualized.

In a developing device having such a configuration, the toner attached to the developing roller is not removed from the developing roller and replaced with new toner other than being consumed for developing the electrostatic latent image, and the toner attached to the developing roller of the hopper is not replaced with new toner. Since pressure is constantly applied between the tip of the side wall in the rotation direction and the charging plate, toner aggregation and assimilation and changes in the amount of triboelectric charging are likely to occur.

this is.

This adversely affects image quality, such as an increase in edge effects and a decrease in image density, and also deteriorates the replenishment of toner from the hopper.

In order to improve these problems, it may be possible to use a toner with good fluidity. This makes the toner less likely to solidify and improves replenishment, but it still solidifies after a long period of time. Furthermore, if a toner with better fluidity is used, although solidification can be prevented, the toner tends to scatter, contaminating the device.

It is also possible to weaken the contact pressure of the charging plate, but the amount of charge on the toner is small and the charge tends to be non-uniform.

The developing device according to the present invention includes a rotating member for removing toner on the developing roller after development.

Thereby, the amount of toner replenishment can be kept constant, and the amount of charging can be kept constant.

In the developing device according to the invention, the rotating member for removing toner is an electrically biased roller. This is in constant contact with the developer roller and removes toner on the developer roller.

The removed toner is collected in a hopper and reused.

Therefore, an object of the present invention is to provide a developing device having a frictional charging plate, which prevents toner from solidifying on a developing roller and improves the quality of a developed image.

A further object of the present invention is to provide the above-mentioned developing device in which the toner on the developing roller is removed by a rotating member after development, thereby improving toner replenishment and keeping the IF charge amount constant.

The present invention will be described in detail below with reference to FIG.

In FIG. 2, reference numeral 16 indicates an electrically biased roller as a rotating member for removing toner.

The toner removing roller 16 is made of metal or conductive rubber, and is disposed between the side wall of the hopper 4 on the upstream side in the rotational direction of the developing roller 1 and the developing roller 1, and is used to remove toner from the hopper 4. A scraper 1 is provided on the upper side wall of the roller 16 to scrape off the toner on the surface of the roller 16.
7 is provided. A DC bias power supply 18 is connected between the developing roller 1 and the roller 15 for removing 1 hener, and a bias voltage having a polarity opposite to that of the toner charged by the charging plate 6 is applied to the roller 16. It has become so.

The toner removing roller 16 is in constant contact with the developing roller 1 and electrostatically absorbs residual toner on the developing roller 1. The toner absorbed onto the surface of the roller 16 is scraped off by a scraper 17 that is in contact with the counter in one direction relative to the rotating direction of the roller 16, and is reused in the hopper as it is.

FIG. 3 shows the relationship between the density of the developed image and the number of times of development in the apparatus shown in the above embodiment and the conventional apparatus.

The one-dot chain line shows the allowable limit A of image density, the solid line shows the relationship in the conventional device B, and the broken line shows the relationship in the device [C] shown in the embodiment according to the present invention. As is clear from the figure, the conventional device [
! In B, when development is performed a certain number of times or more, the image density falls below the allowable limit A, resulting in defective copies. On the other hand, in the apparatus C shown in this embodiment, even if a large number of developments are performed, the image density does not suddenly decrease, but gradually decreases.

However, since the removed toner is reused, a decrease in image density due to fatigue of the I-toner is unavoidable, so when the toner approaches the allowable limit A, the toner is replaced with a new one.

As described above, by using the developing device according to the present invention, it is possible to perform electrostatic latent image development with a constant supply amount of toner and a constant charge amount.

Furthermore, by providing a rotating member that removes the toner on the developing roller between the developing roller and the side wall of the toner replenishing device, it is possible to obtain the effect of stirring the toner within the replenishing device. It is also possible to prevent the toner from solidifying.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram showing an example of a conventional developing device to which the present invention is applied, FIG. 2 is a schematic block diagram showing an embodiment of the present invention, and FIG. FIG. 3 is a diagram showing the relationship between image density and the number of times of development in the apparatus. 1...Developing roller, 2...Photoreceptor, 3,18
...Bias power supply, 4...Hopper, 5...
・-Component non-magnetic toner, 6... Frictional charging plate, 16.
...Rotating member for toner removal. Lost eyes, 9 points, 2 areas

Claims (1)

[Claims] a developing roller having a rubber surface for holding a one-component non-magnetic toner on the surface and bringing it into contact with an electrostatic latent image on a photoreceptor; and a toner replenishing device for supplying the toner onto the developing roller. , a charging plate for frictionally charging the supplied toner, and a charging plate disposed between the side wall of the toner replenishing device on the upstream side in the rotational direction of the developing roller and the developing roller; An electrostatic latent image developing device comprising: a rotating member for removing toner;