JPS606846Y2 - Electrostatic latent image developing device - Google Patents

Description

[Detailed explanation of the idea] This invention relates to an electrostatic latent image developing device.

In general, the electrostatic latent image development method used in devices such as electrophotographic copying machines that use a single precept toner is the magnetic brush development method using magnetic toner, and the touch-down method using non-magnetic toner. This developing method is known.

Even in the latter method, toner is basically transported while adhering to the surface of a rotatable toner carrier covered with an elastic layer, and this toner is transferred by a charge injection electrode to which a voltage is applied in advance. is charged to a predetermined polarity, and the toner is used to visualize the image on the photoreceptor.

However, in many conventional toner carriers, the elastic layer is made of a single material.

However, the development process described above requires low hardness and high conductivity, but when the elastic layer is formed from a single rubber material like this, it is not possible to achieve high conductivity with low hardness. It's difficult.

That is, high conductivity makes it difficult to obtain low hardness, which tends to cause uneven contact with the photoreceptor, resulting in image unevenness and abrasion of the photoreceptor.

On the other hand, when the hardness is low, it becomes difficult to obtain a high conductivity, which leads to a decrease in toner charge amount and bias effect.

Therefore, in order to increase the elasticity of the toner carrier, a multilayer structure was developed in which an elastic foam backing material, a flexible conductive substrate, and resin or graphite were laminated on the outer periphery of a support that constituted a rotating drum. -36070 Publication 52-
This is disclosed in Japanese Patent No. 36414, but because of its multilayer structure, processing is complicated and costs tend to increase.

This invention was developed in view of these points, and it is possible to reduce the contact pressure between the toner carrier and the photoreceptor and expand the contact area with a toner carrier of a simple structure. It is an object of the present invention to provide an electrostatic latent image developing device that can prevent image unevenness.

This idea involves transporting a one-component toner while adhering it to the surface of a rotatable toner carrier coated with an elastic layer.
In an apparatus for visualizing an electrostatic latent image on a photoreceptor, the elastic layer of the toner carrier has a two-layer structure with an inner rubber layer having a hardness lower than that of the outer rubber layer. This is a characteristic feature.

Therefore, by forming the elastic layer into a two-layer structure consisting of an external rubber layer and an internal rubber layer with low hardness, it is possible to obtain high conductivity with a simple structure and low hardness, thereby preventing uneven images. It is designed to be transparent.

An embodiment of this invention will be explained based on the drawings.

This embodiment uses a touch-down development method using non-magnetic toner. First, a drum-shaped photoreceptor 2 is provided which rotates in one direction and forms an electrostatic latent image 1 on its circumferential surface. There is.

This photoreceptor 2 is grounded, and a toner carrier 4 is provided in a bonded state to face the photoreceptor 2 and make the electrostatic latent image 1 into a toner image 3.

A hopper 6 is provided on the surface of the toner carrier 4 to supply a non-magnetic toner 5.

Further, a charge injection electrode 8 is provided in a part of the hopper 6 and is biased by a spring 7 for pressure contact to regulate the layer thickness of the toner 5 supplied onto the toner carrier 4 and also serves as a doctor. It is being

A toner charging power source 9 is connected to this charge injection electrode 8 .

The toner carrier 4 is rotatable in the opposite direction to the photoreceptor 2, and its structure is made up of a cylindrical support 11 supported at both ends by core metal 10, as shown in FIG. An elastic layer 14 having a two-layer structure consisting of an internal rubber layer 12 and an external rubber layer 13 is laminated on the circumferential surface, and the external rubber layer 1
The end portion of 3 is bent and joined to the core metal 10.

Here, the hardness of the internal rubber layer 12 is lower than the hardness of the external rubber layer 13.

The thickness of the outer rubber layer 13 is made as thin as possible, and its electrical resistance is made highly conductive so as to effectively prevent fogging and charge the toner. Bias power supply 15 for preventing fogging
and the toner charging power source 9 are connected.

In such a configuration, the toner 5 is transported to the photoreceptor 2 side while being attached to the surface of the toner carrier 4, but when passing through the charge injection electrode 8, the outermost layer of the toner carrier 4 Since the outer rubber layer 13 is highly conductive, the toner charging power source 9 can be received between the charge injection electrode 8 and the toner charging power source 9 to effectively charge the toner.

Further, since the external rubber layer 13 is highly conductive, it can receive the bias power supply 15 to prevent fogging of the photoreceptor 2.

Regarding the state of contact with the photoreceptor 2, since the low hardness internal rubber layer 12 is provided inside the thin external rubber layer 13 and its elasticity can be fully utilized, the contact pressure is low and the contact This results in even contact, thereby preventing image unevenness and at the same time preventing the photoreceptor 2 from being worn out.

As described above, the two-layer structure consisting of the outer comb layer 13 designed for high conductivity and the inner rubber layer 12 designed for low hardness allows the elastic layer 14 to have low hardness and high conductivity.

Therefore, to summarize the internal rubber layer 12 and the external rubber layer, first of all, regarding the hardness, the external rubber layer 13 may be hard, but preferably it is 45±5H3 or more, and the hardness of the internal rubber layer 12 is that of the external rubber layer 13. Preferably lower than 45±
5) (S or lower is better.

Further, although the electrical resistance of the internal rubber layer 12 does not matter, it is preferable that the external rubber layer 13 has low electrical resistance, that is, high electrical conductivity.

That is, specifically, it has high conductivity of 1010 Ωcm or less, preferably ICP Ωcm or less.

Further, the material of the inner rubber layer 12 may be any material, but the material of the outer rubber layer 13 is not limited to any material in terms of toner adhesion, transportability, image quality, etc., and silicone rubber, neoprene rubber, etc. are preferable.

Further, the thickness of the inner rubber layer 12 is preferably thicker, but the thickness of the outer rubber layer 13 is preferably as thin as possible so that the elasticity due to the low hardness of the inner rubber layer 12 can be fully exhibited.

However, since there is a limit to the thickness of the outer rubber layer 13 due to processing, 0.5 mm is actually sufficient.

Furthermore, the surface roughness is not relevant for the internal rubber layer 12, but it is preferable that the surface roughness for the external rubber layer 13 is 5 μm or less.

In this embodiment, a non-magnetic toner is used as the toner 5, but the present invention can be similarly applied to a toner using a magnetic toner.

As mentioned above, this invention has a two-layer structure for the elastic layer of the toner carrier, consisting of an outer rubber layer and an inner rubber layer with low hardness, so the structure is simple and the elastic layer has low hardness and high conductivity. This has the effect of effectively preventing image unevenness.

[Brief explanation of drawings]

The drawings show an embodiment of this invention, with FIG. 1 being a schematic front view and FIG. 2 being a longitudinal sectional side view of the toner carrier. 2... Photoreceptor, 4... Toner carrier,
5... Toner, 8... Charge injection electrode,
12...Inner comb layer, 13...Outer rubber layer, 14...Elastic body layer.

Claims (1)

[Scope of utility model registration request] A one-component toner is attached to the surface of a rotatable toner carrier coated with an elastic layer and transported to visualize an electrostatic latent image on a photoreceptor,
The elastic layer of the toner carrier is characterized in that it has a two-layer structure consisting of a highly conductive outer rubber layer with a surface roughness of 5 μm or less and an inner rubber layer whose hardness is lower than that of the outer rubber layer. Electrostatic latent image developing device.