JPH08179624A - Developing device - Google Patents

Abstract

PURPOSE: To prevent the decrease in developing density in the initial period of developing operation and the occurrence of initial fogging by applying a charge control material on the pressurized contact parts of a thin layer forming member with a toner carrying member. CONSTITUTION: A toner blade 3 is bent in such a manner that the radius of curvature on the inner side in the pressurized contact part with a developing roller 2 attains a prescribed value. The outer side of this round part (the pressurized contact part side with the developing roller 2) is coated with oily ink 12 in such a manner that its thickness attains >=0.05mm. The dyes and pigments contained in the oily ink 12 act as the charge control agent in the initial period of the development operation and, therefore, a uniform electrostatic charge quantity is obtd. with the individual particles of toners. Namely, if the stabilizing of the electrostatic charge quantity in the oily ink 12 is possible in the initial period of the development operation, the development is henceforce executed repetitively, by which the decrease in the development density and the occurrence of the initial fogging are no longer admitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device, and more particularly to a developing device using an electrophotographic process.

[0002]

2. Description of the Related Art Conventionally, in a developing device using a non-magnetic one-component toner, a non-magnetic one-component toner (hereinafter referred to as a toner) stored in a toner hopper is carried by rotating a toner mixer and a toner supply roller. Supplying to the developing roller which is the body.

An elastic blade made of rubber or metal as a thin layer forming member is pressed against the peripheral surface of the developing roller, and a thin layer of toner is formed on the surface by the elastic blade, and at the same time, it is elastic with the developing roller. The toner is charged by the friction of the pressure contact portion with the blade.

The electrostatic latent image formed on the photoconductor is developed by making the thin layer of the charged toner face a photoconductor which is an image carrier for carrying an image.

[0005]

In the above-described conventional developing device, the surface roughness of the developing roller is rough at the initial stage of the developing operation, and the amount of toner adhering to the developing roller is large. In the triboelectrification method using a non-magnetic one-component toner, the toner is charged by the contact and friction between the developing roller and the elastic blade. The individual toners cannot be uniformly subjected to triboelectric charging, and toners having a large charge amount or toners having a small charge amount are generated, and the charge amount distribution is widened.

Further, the developing device is often in a stationary (storing) state for a long period before starting the developing operation,
Since the toner is close to a state in which it is not charged at all, variations in the amount of charge of each toner are likely to occur when the charge of the toner rises at the beginning of the developing operation. For this reason, the development density becomes low and initial fog occurs at the beginning of the development operation.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above problems and to provide a developing device capable of preventing the development density from becoming low and the occurrence of initial fog at the beginning of the developing operation. .

[0008]

SUMMARY OF THE INVENTION A developing device according to the present invention comprises a toner carrier that rotates while contacting the peripheral surface of an image carrier that carries an image to be developed, and a non-magnetic one-component toner on the toner carrier. A developing device including a supply roller for supplying and a thin layer forming member that presses against the surface of the toner carrier to form a toner layer, and is applied to a portion of the thin layer forming member that is in pressure contact with the toner carrier. Equipped with a charge control agent.

[0009]

[Function] While thinning the toner on the developing roller,
The oil-based ink is applied to the pressure-contact portion of the frictionally charged toner blade with the developing roller.

As a result, it is possible to stabilize the charge amount of the toner at the initial stage of the developing operation and at the same time narrow the charge amount distribution of the toner. Therefore, it is possible to prevent the development density from becoming thin and the initial fog to occur. However, a good image can be obtained from the initial stage of the developing operation.

[0011]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, a non-magnetic one-component toner (hereinafter referred to as toner) 10 stored in a toner hopper 9 of a developing device 11
Is sent to the developing chamber 5 by rotation of the toner mixer 8 in the direction of arrow a.

The toner 10 sent to the developing chamber 5 adheres to the supply roller 4, and adheres to the developing roller 2 rotating in the same direction as the supply roller 4 (direction of arrow b). The toner 10 adhering to the developing roller 2 enters the pressure contact portion between the developing roller 2 and the toner blade 3 as the developing roller 2 rotates, is thinned on the developing roller 2 by the toner blade 3, and is triboelectrically charged. To be done.

Toner 1 frictionally charged on the developing roller 2
0 is an electrostatic latent image formed on the image carrier (photoreceptor) 1 which passes through the pressure contact portion between the developing roller 2 and the toner blade 3 and is rotating in the same direction as the developing roller 2 (direction of arrow b). Is conveyed by the rotation of the developing roller 2, and the electrostatic latent image is developed and visualized.

The toner 10 remaining on the developing roller 2 without being developed passes through a gap between the developing roller 2 and the seal member 7 attached to the casing 6, and is conveyed to a sliding contact portion with the supply roller 4. . The toner 10 conveyed to the sliding contact portion between the developing roller 2 and the supply roller 4 is peeled off from the developing roller 2 by the supply roller 4 and mixed with the toner 10 in the developing chamber 5.

FIG. 2 is a view showing a pressure contact portion between the developing roller 2 and the toner blade 3 in FIG. In the drawing, the toner blade 3 is bent so that the inner radius R is 0.2 mm at the pressure contact portion with the developing roller 2, and the oil-based ink 12 is provided on the outer side of this R portion (the pressure contact portion side with the developing roller 2). Is applied to have a thickness of 0.05 mm or more.
The material of the toner blade 3 is SUS304CS.
P (t = 0.1 mm) is used.

By applying the oil-based ink 12 to the portion of the toner blade 3 that is in pressure contact with the developing roller 2, the dye or pigment contained in the oil-based ink 12 acts as a charge control agent at the beginning of the developing operation. A uniform charge amount is obtained for each of the particles.

Here, the toner 10 itself in the developing chamber also contains a charge control agent mainly composed of a dye (organic metal complex having a central metal such as a metal-containing azo dye). The control agent alone is insufficient to stabilize the charge amount at the beginning of the developing operation.

The fact that the developing density becomes low or the initial fog occurs at the beginning of the developing operation is a phenomenon that appears uniquely when the developing roller 2 is new, and cannot be seen after printing to some extent. Therefore, if the charge amount of the toner 10 can be stabilized by the action of the charge control agent by the dye or pigment in the oil-based ink 12 at the beginning of the developing operation, the development density is reduced by the repeated development thereafter, and Since the phenomenon of fogging is not seen, there is no problem even if the oil-based ink 12 disappears due to friction between the toner blade 3 and the developing roller 2.

The time when the oil-based ink 12 is applied to the toner blade 3 is before the contact with the developing roller 2 when the toner blade 3 is used alone or when it is incorporated in the developing device 11. In any case, the toner blade 3 is fixed, the contact pressure between the bent portion of the toner blade 3 and the pen tip for applying oil-based ink such as felt is set to 200 g, and the pen for oil-based ink application is reciprocated once. The oil-based ink 12 is evenly applied to the toner blade 3.

As described above, by applying the oil-based ink 12 to the pressure contact portion of the toner blade 3 with the developing roller 2,
By stabilizing the charge amount of the toner 10 at the initial stage of the developing operation and narrowing the charge amount distribution of the toner 10 at the same time,
It is possible to prevent the development density from becoming low and the occurrence of initial fog, and it is possible to obtain a good image from the beginning of the developing operation.

FIG. 3 is a diagram for explaining the transition of the reflection density according to the embodiment of the present invention. In the figure, Δ indicates the oil-based ink 1 at the portion where the toner blade 3 is pressed against the developing roller 2.
2 shows the transition of the reflection density when the toner 2 was applied, and □ shows the transition of the reflection density when the oil-based ink 12 was not applied to the portion where the toner blade 3 was pressed against the developing roller 2.

When 400 sheets are printed by the developing device 11 in which the oil-based ink 12 is applied to the contact portion of the toner blade 3 with the developing roller 2, the initial fog density is 0.001.
On the other hand, when 400 sheets are printed by the developing device in which the oil-based ink 12 is not applied to the contact portion of the toner blade 3 with the developing roller 2, the initial fog density is 0.016.

As described above, by applying the oil-based ink 12 to the contact portion of the toner blade 3 with the developing roller 2, the charge amount of the toner 10 at the initial stage of the developing operation can be stabilized, and at the same time, the toner 10 can be charged. The charge amount distribution can be narrowed. Therefore, it is possible to prevent the development density from becoming low and the occurrence of initial fog, and it is possible to obtain a good image from the initial stage of the developing operation.

[0025]

As described above, according to the present invention, the charge control agent is applied to the pressure contact portion between the toner carrier and the thin layer forming member that pressure contacts the surface of the toner carrier to form the toner layer. There is an effect that it is possible to prevent the development density from becoming low and the occurrence of initial fog at the beginning of the development operation.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a view showing a pressure contact portion between a developing roller and a toner blade of FIG.

FIG. 3 is a diagram for explaining a transition of reflection density according to an embodiment of the present invention.

[Explanation of symbols]

 1 image carrier 2 developing roller 3 toner blade 4 supply roller 5 developing chamber 8 toner mixer 9 toner hopper 10 non-magnetic one-component toner 12 oil-based ink

Claims (3)

[Claims] 1. A toner carrier that rotates while being in contact with a peripheral surface of an image carrier that carries an image to be developed, a supply roller that supplies non-magnetic one-component toner to the toner carrier, and a surface of the toner carrier. A thin-layer forming member that presses against the toner to form a toner layer, wherein the developing device has a charge control agent applied to a portion of the thin-layer forming member that is pressed against the toner carrier. Development device. 2. The developing device according to claim 1, wherein the charge control agent is an oil-based ink containing at least one of a dye and a pigment. 3. The developing device according to claim 1, wherein the charge control agent has a film thickness of 0.05 mm or more.