JPS62223771A - Developing device - Google Patents

Abstract

PURPOSE:To obtain an image of high quality by forming an flexible conductive layer on the surface of an elastic roll to constitute a developing roll and forming a proper contact width between the developing roll and an electrostatic latent image holding body. CONSTITUTION:The developing roll 1 forming a toner layer on its surface is rotated around its axis while holding a required contact width with a photosensitive drum 9 holding an electrostatic latent image at its surface. In case the contact width between the drum 9 and the roll 1 is less than a prescribed value, the electrostatic latent image is not properly developed. By constituting the roll 1 by forming a flexible elastic layer consisting of urethane foam around a metallic shaft and forming a flexible conductive layer around the elastic layer, the roll 1 holding toner 4 on its outer periphery is rotated and pressed against the drum 9 while keeping a proper contact width and appropriate development is executed.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention relates to a developing device that visualizes an electrostatic latent image formed on a photoreceptor or a dielectric material, and particularly relates to a developing device that visualizes an electrostatic latent image formed on a photoreceptor or a dielectric material. The present invention relates to a developing device using a one-component non-magnetic developer that does not require magnets or magnets.

(Prior Art) Conventionally, developing devices using a one-component non-magnetic developer are disclosed in U.S. Pat.
Fur brush developing device disclosed in No. 05 etc.
Impression developing devices disclosed in US Pat. No. 3,731,146 and powder cloud developing devices disclosed in US Pat. No. 2,725,304 are known.

First, the fur brush developing device applies a triboelectric charge to the toner using animal fur and short fibers, but there are problems such as image deterioration in high humidity and image deterioration due to changes in the nap of the fur. was there.

Further, the powder cloud developing device uses atomized toner powder for development, which increases the size of the device and has problems such as scattering of the toner powder.

The impression developing device forms a layer of toner on the surface of a conductive rubber roller using an applicator, and develops the toner by pressing it against a photoreceptor.

Here, it is important to select the (A quality) so that the surfaces of the applicator and the developing roller are triboelectrically charged to the opposite polarity to the toner.

For this reason, the materials for the surface of the applicator and developing roller are limited, and conductive rubber is generally hard and lacks flexibility, so when developing in contact with a drum-shaped photoreceptor, the developing nip must be set wide. There were problems such as that it was difficult to do so.

In particular, when the developing nip is narrow, the contact time between the electrostatic latent image and the toner layer becomes short, making it impossible to produce a good image.

In addition, in order to obtain higher quality images, it is important to create a speed difference between the electrostatic latent image and the developing roller so that they rub against each other. When the developing roller is configured, it is actually extremely difficult to cause the developing roller to rub the photosensitive drum once while maintaining a sufficient developing nip width.

(Problems to be Solved by the Invention) As described above, the conventional developing device using a one-component nonmagnetic developer has a problem in that it is unable to form a high-quality image.

The present invention has been made to address the above-mentioned drawbacks of the conventional apparatus, and an object of the present invention is to provide a developing apparatus capable of obtaining a high-quality developed image with a simple configuration using a -component non-magnetic developer. .

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a developing device that supplies a developer to an electrostatic latent image holder to visualize it. A flexible conductive layer is provided on the outer peripheral surface of the elastic roll, and a one-component non-magnetic ring imager is charged with tribostatic charge on the surface of the conductive layer. A developer layer forming means for forming a thin layer and a means for applying a voltage to the conductive layer are provided, and the thin layer of the developer formed on the surface of the conductive layer contacts the electrostatic latent image carrier. The elastic rolls are arranged so as to touch or rub against each other.

(Function) Therefore, the developing roll formed of the elastic roll and the flexible conductive layer covering the surface of the elastic roll has flexibility, and the developing roll is suitable for the electrostatic latent image carrier and the flexible conductive layer covering the surface of the elastic roll. Contact or one brush stroke with the contact width.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view schematically showing an embodiment of a developing device according to the present invention.

This developing device includes a developing roll 1, an elastic plate 2 pressed against the developing roll 1, a holder 3 to which one end of the elastic plate 2 is fixed, a toner container 5 containing toner 4, etc.
It consists of an elastic film 6 that prevents the toner 4 from falling out of the toner container 5, a casing 7 to which the elastic film 6 is fixed, and a power source 8 that applies voltage to the developing roll 1. It is configured to be pressed against the body drum 9.

This developing roll 1 is rotated by a drive device (not shown) in the direction of the arrow shown in FIG.
An elastic plate 2 made of a phosphor bronze plate or the like is pressed.

Also, one end of this elastic plate 2 is fixed to a holder 3,
The other end, that is, the free end, is arranged so as not to contact the developing roll 1.

That is, in order to obtain a good image, it is necessary to form a uniform thin layer of charged toner 4 on the surface of the developing roll 1, but as described above, the sides of the elastic plate 2 excluding the edges are 1, it is possible to form a single layer of toner that satisfies such requirements.

It is also possible to form a relatively uniform layer of toner when the edge of the elastic plate 2 is pressed against the developing roll 1; however, in this case, the edge of the elastic plate 2 should not have any unevenness such as burrs. Therefore, it is necessary to improve the machining accuracy.

On the other hand, the toner 4 must be given a triboelectric charge having a polarity opposite to that of the latent image charge through contact with the elastic plate 2 and the developing roll 1. Therefore, it is necessary to use those having sufficient polarity control.

Therefore, in this example, we used a negatively charged type resin with an average particle diameter of 1
A 2 μm non-magnetic toner is used.

It is desirable to use a metal plate as the elastic plate 2 in order to always give a constant value of tribocharge to the toner 4, but any material that can give the toner 4 a tribocharge of the opposite polarity to the latent image charge may be used. A high resistance material or an insulator can also be used.

In this embodiment, the elastic plate 2 has a thickness of 0.15 mm.
A stainless steel plate of 1 ml was used, and the length from the center of the contact position with the developing roll 1 to the fixed end was 27 mm, and the length to the free end was 3 mm.

In addition, the elastic film 6 has the function of returning toner remaining on the surface of the developing roll 1 without contributing to the development of the electrostatic latent image into the toner container 5 as the developing roll 1 rotates, and of returning the toner in the toner container 5. It has the function of preventing spillage to the outside.

In this embodiment, a polyester film with a thickness of 100 μm is used as the elastic film 6, and one end is fixed to the lower part of the casing 7.

FIG. 2 is a partial sectional view of the developing roll 1 in this developing device.

This developing roll 1 includes a metal shaft 10, a flexible elastic layer 11 made of foamed urethane provided on the outer periphery, a polyester tube 12 bonded to the outer periphery, and a polyester tube 12 provided on the outer periphery of the polyester tube 12. It is composed of a conductive layer 13 having a conductive property.

In this embodiment, as the conductive layer 13, a special film (of aluminum) deposited on the outer periphery of the polyester tube 12 is used.

Note that this conductive layer 13 can also be made of a conductive layer in which carbon is dispersed in resin.

The polyester tube 12 having a thin aluminum film on its surface is bent at the end of the developing roll 1 and processed so that the aluminum thin film contacts the shaft 10. Therefore, a developing bias can be applied to the conductive layer 13 via the shaft 10.

Next, the operation of this developing device will be explained.

The above-mentioned developing roll 1 is brought into contact with the photoreceptor drum 9, and the first
When rotated in the direction of the arrow shown in the figure, the toner 4 in the toner container 5 slips under the pressure of the elastic plate 2, adheres to the surface of the developing roll 1 due to the triboelectric charge acquired at this time, and is attached to the surface of the photoreceptor drum 9. will be transported towards.

At this time, the nip width between the photoreceptor drum 9 and the developing roll 1 is set to 8
mm, the surface potential of the photoreceptor drum 9 is +700V, the developing bias applied to the conductive layer 13 on the surface of the developing roll 1 by the power source 8 is +200V, the surface speed of the photoreceptor drum 9 and the surface speed of the developing roll 1 is 110 mm/sec.
A good developed image can be obtained by performing development as follows.

On the other hand, when development was carried out with the nip width set to 2 mm, the resulting image was insufficient in image density and resolution.

As described above, in forming a developed image, the developing nip or the contact time between the electrostatic latent image and the toner layer is important, and this embodiment can flexibly meet such requirements.

That is, for example, development can be carried out by setting the developing nip width to 8 mm and the surface speed of the developing roll 1 to 1.5 times the surface speed of the photoreceptor drum 9. In this case, the developing roll 1 and the photoreceptor drum 9 are It is possible to obtain an image with roughly better image Ia degree and resolution than the image obtained by contacting at the same speed.

As described above, this embodiment constitutes the elastic layer 11 (A
Since there are no particular restrictions on the electrical conductivity or triboelectricity of the material, a flexible material such as urethane foam can be used.

A flexible conductive layer 13 is provided on the surface of the elastic layer 11, and this supports a single layer of toner, so even when the photoreceptor drum 8 is made of a hard material, sufficient You can get the nip width.

It is also possible to rub the developing roll against the photoreceptor drum 9 while maintaining a sufficient developing nip width, thereby making it possible to obtain an image of relatively good quality.

[Effects of the Invention] As explained above, according to the present invention, since the flexible conductive layer is provided on the surface of the elastic roll, the thin layer of developer and the electrostatic latent image carrier are properly connected. It is possible to make contact or rub with a certain contact width, and it is possible to obtain a high-quality image.

[Brief explanation of drawings]

FIG. 1 is a sectional view schematically showing one embodiment of the present invention, and FIG.
The figure is a partial sectional view of the developing roll in the same embodiment. 1...Development roll 2...Elastic plate 4...Non-magnetic toner 8...Power supply 9. ..... Photosensitive drum 10 ..... Shaft 11 ..... Elastic layer 12 ..... Polyester tube 13 ...
... Conductive layer applicant Toshiba Corporation Patent attorney Satoshi Suyama - Figure 1 Figure 22

Claims (8)

[Claims] (1) In a developing device that supplies developer to an electrostatic latent image holder and visualizes it, an elastic roll is rotatably supported, and a flexible roller is provided on the outer peripheral surface of the elastic roll. a developer layer forming means for forming a thin layer of a one-component non-magnetic developer charged with a tribostatic charge on the surface of the conductive layer, and means for applying a voltage to the conductive layer; . A developing device, characterized in that the elastic roll is arranged so that the thin layer of the developer formed on the surface of the conductive layer contacts or rubs against the electrostatic latent image holder. (2) Patent claim that the elastic roll consists of a metallic roll-shaped core, a cylindrical elastic member provided on the outer peripheral surface of this core, and a cylindrical film provided on the outer peripheral surface of this elastic member. The developing device according to item 1. (3) The developing device according to claim 2, wherein the conductive layer is provided on the outer peripheral surface of the cylindrical film. (4) The developing device according to claim 2 or 3, wherein the cylindrical elastic member is made of polyurethane foam. (5) The developing device according to claim 1, wherein the elastic roll is arranged so that the nip width between the conductive layer and the electrostatic latent image holder is 3 mm or more. (6) The developing device according to claim 1, wherein the developer layer forming means comprises a rigid blade or an elastic blade, and an end or side surface of the blade is pressed against the conductive layer. (7) The developing device according to claim 6, wherein the blade is made of a metal body. (8) The developing device according to claim 6, wherein the blade is made of a dielectric material that imparts to the developer a tribostatic charge of a polarity opposite to that of the electrostatic latent image.