JPH033228B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fur brush type developing device used, for example, in electronic copying machines, electronic printing devices, and the like.

Recently, an economical fur brush type developing device that does not use a carrier (iron powder) has been proposed for electronic copying machines and the like. As shown in Fig. 1, this type of developing device has a long hair body a.
Roller b as a fur brush developing means having
There are two methods in which the surface of the photoconductor c is developed by stroking it with
There is a developing method using a roller f as a fur brush developing means, in which the core e is made soft so that the portion in contact with the surface of the photoreceptor c is bent.

However, in the former fur brush developing roller b having long bristles a, the bristles a get worn out after long-term use, the developing bias for preventing fogging is ineffective, and excess toner is released as the fur brush developing roller b rotates. A smoke state is formed, and uncharged toner causes significant fogging. In order to prevent this, a fog prevention roller g must be added, and the structure becomes complicated.

On the other hand, the fur brush developing roller f which uses the latter short bristles d and has a soft core e has a developing bias voltage i for preventing fogging by fixing the core e and the bristles d with a conductive adhesive h. It becomes possible to apply the voltage. However, the conditions for the antifogging developing bias voltage i to work effectively are that a certain amount of toner must be supplied, and that the toner held by the bristles d is sufficient to be charged by friction with the bristles d. must be done. If the amount of toner is large, the hair body d
Although this is partly related to the density of
Fogging occurs. Conversely, if the amount of toner is small, the density of development will decrease. Therefore, it is necessary to arrange the toner charging roller j and the toner supply roller k near the fur brush developing roller f, which makes the structure complicated and increases the rotational torque between the rollers f, j, and k. However, the drawback is that a powerful motor is required, which increases the price.

The present invention was made based on the above circumstances, and
Its purpose is to have a relatively simple configuration,
It is an object of the present invention to provide a developing device that prevents fogging due to uncharged toner and provides a good developing state by sufficiently charging the toner supplied to a fur brush developing means.

Hereinafter, one embodiment of the present invention will be described based on FIG. 3. 1 in the figure is toner storage box (hopper) 2
A fur brush developing roller 4 having a portion thereof in contact with the surface of the photoreceptor 3 is accommodated in the developing container 1 . This fur brush developing roller 4 is made of short bristles 7 as a fur coated with a conductive adhesive 6 on a soft core (elastic body) 5.
It has a fixed configuration. Here short hair body 7
The length is 0.5~5mm, the thickness is 1.5~10d (denier)
In this embodiment, the length is set to 2 mm and the thickness is set to 5 d, as an example.

Further, a toner replenishment roller 8 is provided at the toner replenishment port of the toner storage box 2.
The toner 9 inside is supplied into the developer container 1 as the toner supply roller 8 rotates.

Further, a DC bias voltage 1 for forcibly charging the toner is provided at the bottom of the inner wall surface of the developer container 1 in a state in which it is in close proximity to or in contact with the bristles 7 of the fur brush developing roller 4.
A sheet-like electrode 11 to which 0 is applied is provided.

Furthermore, the fur brush developing roller 4 has bristles 7.
An AC bias voltage 12 for preventing fogging is applied from the back surface of the bristles 7 so that an AC electric field is applied to the bristles.

Thus, when the toner 9 supplied into the developer container 1 by the toner replenishing roller 8 passes through the sheet electrode 11 to which the DC bias voltage 10 is applied, the toner 9 is forcibly charged, which is necessary for development. Maintain a certain amount of charge. At this time, when zinc oxide is used for the photoreceptor 3 and an electrostatic latent image is formed with negative charge, a positive DC voltage is applied to the sheet electrode 11 so that the toner 9 has a positive charge. If the potential of the photoreceptor 3 is a positive charge, a negative DC voltage is applied.

At this time, most of the toner 9 is charged due to the bias applied to the sheet electrode 11, but
Some of the toners 9 have not yet reached the saturation value. In addition, since the resistance of the toner 9 used in this method is relatively low, the toner 9 that has not reached the saturation value is injected with the charge from the photoconductor 3, and the toner 9
Development occurs in the form of scattering of..., and furthermore, those toners 9... appear as fog in the developed image.

Therefore, in order to prevent this, an alternating current electric field with a frequency of 1 KHz is generated from the back surface of the bristles 7 to collect unsaturated toner.

In the above-mentioned embodiment, an alternating current electric field was applied to the fur brush developing roller 4, but the toner 9
A DC bias having a polarity opposite to that of the charge may be applied.

In addition, it goes without saying that the present invention can be modified in various ways without departing from the gist of the invention.

As explained above, according to the present invention, the structure is relatively simple and inexpensive, and the toner supplied to the fur brush developing means is sufficiently charged, and uncharged toner is collected to the fur brush developing means side. This has the effect that good development can be performed without fog caused by uncharged toner.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a conventional fur brush developing device, FIG. 2 is a schematic diagram of a different conventional fur brush type developing device, and FIG. 3 is a schematic diagram of an embodiment of the developing device of the present invention. It is a diagram. 1...Developing container, 4...Fur brush developing roller,
7... Fur, 9... Toner, 10... DC bias voltage for forcibly charging toner, 12... AC bias voltage for anti-fogging measures.

Claims (1)

[Scope of Claims] 1. A fur brush developing roller made of flocked short fibers is housed in a developing container, and the toner is forced onto the inner wall of the developing container so that the fur of the fur brush developing roller approaches or comes into contact with the fur brush developing roller. A developing device comprising: a charging member; further comprising: applying a bias voltage to the toner forcible charging member; and applying an AC bias voltage from the rear surface of the fur so that an AC electric field is applied to the fur.