JPS6356990B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a developing device of an electrophotographic apparatus, and more specifically, to a developing device in which dry toner particles are conveyed to an electrostatic latent image on a photoreceptor by a developing fur brush roll to form a toner image. The present invention relates to an improvement of a fur brush developing device.

Conventionally, when carrying toner particles to an electrostatic latent image on a photoconductor to form a toner image, it is common to apply a bias voltage to the developing fur brush roll in order to remove fog in non-image areas. This is a well-known method.

However, by repeating the developing operation many times to apply a voltage with a polarity that attracts toner particles, the bias voltage gradually accumulates toner particles on the developing fur brush roll until the amount of toner particles balances the applied voltage of the bias voltage. Once the toner particles have adhered, the bias voltage no longer effectively acts on the fogging toner particles as an external electric field.

Furthermore, when toner particles accumulate on the developing fur brush roll, the effect of the developing electrode of the developing fur brush roll is lost due to the increased electrical resistance of the developing layer, resulting in development with a high edge effect. It becomes like this. Furthermore, when the accumulation of toner particles on the developing fur brush roll increases and becomes excessive, there is a problem in that the toner particles scatter and contaminate the inside of the copying machine.

The present invention has been developed based on the above circumstances, and its purpose is to prevent the toner particles adhering to the developing fur brush from accumulating more than a certain level, and to prevent fogging and edge effects, while having an extremely simple structure. It is an object of the present invention to provide a new fur brush developing device that provides images free of dust and that does not cause scattering of toner particles.

Hereinafter, the present invention will be explained with reference to an illustrated embodiment.

FIG. 1 schematically shows an example of an electrophotographic apparatus to which the present invention is applied.

The photosensitive drum 1 has a photoconductive insulating layer on its surface and rotates at a constant speed in a clockwise direction. Inorganic semiconductors such as selenium, cadmium sulfide, and zinc oxide, and organic semiconductors such as polyvinyl carbazole are used for the photoconductive insulating layer, and each has different usage characteristics. In this example, zinc oxide is used. The surface of the zinc oxide photoreceptor is uniformly charged to negative polarity by a corona charger 2. Subsequently, in order to form an electrostatic latent image on the surface of this photoreceptor, the original platen 3 is irradiated with a halogen exposure lamp 4, and imagewise exposed with a self-occurrence lens (trade name) 5. Subsequently, this electrostatic latent image is developed by the fur brush developing device 6 of the present invention. Corona transfer in which the transfer paper 8 fed from the paper cassette 7 by the paper feed roll 9 and the resist roll pair 10 is superimposed on the toner image on the photoreceptor obtained by development, and a voltage of negative polarity is applied. The toner image is transferred to the transfer paper 8 by the charger 11 and transferred. Subsequently, the transfer paper 8 is separated from the photoreceptor drum 1 by a corona separation charger 12 to which an alternating current voltage is applied, placed on a conveyor belt 13, and conveyed to a heat roll fixing device 14, where the toner image on the transfer paper 8 is fixed and discharged. It is discharged onto a tray 16 by a pair of rolls 15.

Since the residual toner remaining after transfer and the electrostatic latent image charge on the photoreceptor remain on the surface of the photoreceptor after the transfer, the electrostatic latent image charge is eliminated by the discharge lamp 17, and the residual toner is removed by the cleaner 18. The copy cycle ends.

Next, an embodiment of the fur brush developing device 6 according to the present invention will be described with reference to FIG.

19 in Figure 2 is the toner storage box (toner hopper)
20, and this developer container 1
A developing fur brush roll 21 having a portion thereof in contact with the surface of the photoreceptor 1 is housed in the roller 9, and is adapted to rotate clockwise (indicated by the arrow) in the state shown in FIG.

Also, the toner supply port 20a of the toner storage box 20
Nearby are non-magnetic dry toner particles (hereinafter simply referred to as non-magnetic toner) a... (partially enlarged in the figure)
The toner supply roll 22 that supplies the toner into the developer container 19 is a fur brush roll having bristles on the surface;
Or it consists of a metal roll with an uneven surface,
In the state shown in FIG. 2, it rotates counterclockwise (indicated by the arrow). Furthermore, a toner amount regulating member 23 is provided close to the top of the toner supply roll 22 .

Further, a lower end of the developing fur brush roll 21 on the anti-photoreceptor drum 1 side is connected to a developing container 19.
and the toner storage box 20, and the upper end is fixed to the holder 24 horizontally suspended above the developing fur brush roll 21, and the middle part is the bristles of the developing fur brush roll 21. 21a
A mesh blade 25 for collecting toner is provided with its surface in contact with....

Further, on the outside of the mesh blade 25, a non-magnetic toner a...
The toner supply roll 22 is in pressure contact with the toner supply roll 22, and the non-magnetic toner a remaining on the surface of the toner supply roll 22 is once scraped off, thereby ensuring good toner supply.

As the toner supply roll 22 rotates, the non-magnetic toner a adheres to the outer circumference of the roll 22.
A portion of the non-magnetic toner a is scraped off by the toner amount regulating member 23, so that an appropriate amount of non-magnetic toner a can be supplied to the developing fur brush roll 21. The developing fur brush roll 21 that has been supplied with the non-magnetic toner a is rotating in the direction of the arrow in FIG. Develop the electrolatent image. After development, unconsumed toner a' (partially enlarged in the figure) remains on the developing fur brush roll 21 depending on the distribution of the electrostatic latent image on the photoreceptor drum 1. The toner a' is collected by the toner collecting mesh blade 25, and is again supplied with an appropriate amount of toner by the toner supply roll 22.

In this embodiment, the mesh blade 25 has a square mesh of 1.3 mm on each side, and the thickness of the wire is 0.2 mm.
However, if 5 m/cm ² of unconsumed toner a' is attached to the surface of the developing fur brush roller 21, when the mesh blade 25 is pressed against the mesh blade 25 with a constant tension, approximately 3 mg/cm ² of unconsumed toner a'... was recovered. Further, the amount of toner used to develop the electrostatic latent image on the surface of the photoreceptor drum 1 is approximately 1.5
mg/ ^cm2 . Therefore, in this case, the developing fur brush roll 21 is supplied by the toner supply roll 22.
It is sufficient to constantly supply 3 mg/cm ² of non-magnetic toner a. By changing the distance between the surface of the toner supply roll 22 and the toner amount regulating member 23, the developing fur brush roll 21 can be adjusted to the mesh blade 25.
Since the amount of toner received via the toner can be controlled, an appropriate amount of non-magnetic toner a can always be supplied to the developing fur brush roll 21.

Furthermore, when the mesh blade 25 is made conductive and an alternating current voltage is applied to it, unconsumed toner a...
This makes it easier to remove the toner, and toner recovery is further promoted.

As explained above, the present invention provides a mesh blade in surface contact with the developing fur brush after forming a toner image, and removes unconsumed toner adhering to the bristles of the developing fur brush roll. Although it is an extremely simple structure that can be collected,
It is possible to always keep the amount of toner on the fur brush for development at an appropriate level, thus eliminating background fog and edge effects, which are the biggest drawbacks of fur brush development.
The effect is that toner scattering can be prevented.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an electrophotographic apparatus employing an embodiment of the present invention, and FIG. 2 is a schematic longitudinal sectional side view showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Photosensitive drum, 6...Fur brush developing device, 21...Fur brush roll for development, a...Dry toner particles (non-magnetic toner), 25...Mesh blade for collecting toner, a'...Unconsumed toner.

Claims (1)

[Scope of Claims] 1. In a device in which a toner image is formed by transporting dry toner particles to an electrostatic latent image forming surface by a developing fur brush, the toner particles are brought into surface contact with the developing fur brush after the toner image has been formed. A fur brush developing device comprising a mesh blade for collecting unconsumed toner adhering to a developing fur brush. 2. The fur brush developing device according to claim 1, wherein the mesh blade for collecting unconsumed toner is electrically conductive, and an alternating current voltage is applied to the mesh blade.