JPH05188764A - Developing device - Google Patents

Abstract

PURPOSE:To provide a one-component developing device which maintains a contrast solid image as the advantage of the one-component developing device, and can more sharply reproduce a fine line image, an ordinary line image, and a dot image, with an edge effect. CONSTITUTION:In the one-component developing device, the developing sleeve 13 of a toner carrier 130 is composed of a dielectric (binder) 13a including a conductive long carbon fiber 13b, a long fiber is, consecutive in the longitudinal direction of the toner carrier 130, and included so as to alternately arrange the long fiber and the binder 13a, and so as to apply a developing bias, and the toner carrier 130 is driven so as to make the moving speed of the surface of the carrier 130 different from that of the surface of a photosensitive drum PC.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-component developing device used in an image forming apparatus such as a copying machine or a printer. The present invention relates to a one-component developing device for supplying a thin layer of the developer to the electrostatic latent image on the surface of the electrostatic latent image carrier by the movement of the developer to visualize the latent image.

[0002]

2. Description of the Related Art In a developing device of this type, a developer carrying member is usually frictionally charged on the surface of the developer carrying member, and a regulating member for regulating the conveying amount thereof is pressed against the surface of the developer carrier. By passing through, it is charged, is formed into a thin layer of a predetermined thickness on the carrier, and is conveyed to the developing area,
Here, it is subjected to contact development with an electrostatic latent image under application of a development bias.

In FIG. 3A, the γ characteristic curve (developing characteristic curve) of the one-component developing device, that is, the horizontal axis represents the image exposure portion surface potential Vi of the electrostatic latent image carrier and the developing bias Vb. Of the image density I.D. D. Taking an example of a curve showing the change in image density with respect to the change in the difference, when the developer carrying member is made of a conductive material such as Ni, a solid image, that is, a line a in a solid black image is shown. As shown by, the γ characteristic is well established and a high contrast image can be obtained. Also, for a line image having a certain thickness, as shown by the line b, the γ characteristic stands well,
A high contrast image is obtained.

Generally, the solid portion and the line portion have different developing characteristics and the reproducibility thereof is different. However, in the developing which does not require gradation expression in a printer or the like, both the solid portion image and the line portion image have a high contrast and a high contrast. An image of density is required. The one-component development method that does not use a carrier can easily achieve small size, light weight, and low cost.
The development characteristics of the solid part and the line part are the same as those of the two-component developing device, and the print image density rises sharply with respect to the original image density. It is widely used as a device.

Incidentally, FIG. 3C shows an example of γ characteristics in a two-component developing apparatus mainly composed of carrier and toner. Line e is a solid image and line f is a γ characteristic of a line image. Is shown.

[0006]

However, in a one-component developing device, when a conductive developer carrier such as Ni is used for contact development, the latent image on the photoreceptor is reproduced too faithfully. In the case of a latent image in which the surface potential of the electrostatic latent image carrier such as a thin line such as a dot line or a small dot such as 1 dot does not drop, as shown by a dotted line b1 in FIG. However, there is a problem in that the γ characteristic becomes sluggish, the lines and dots are not clearly reproduced, and are faint.

On the other hand, in the two-component contact developing apparatus, by setting the electric resistance value of the carrier to a certain degree high, the lines of electric force generated from the line latent image are largely distorted in the vicinity of the carrier particles and the electric field in the edge portion is strengthened. It is known that a so-called edge effect occurs and an image having a high copy or print image density is reproduced even when the original image density is low, so that even fine lines or small dots can be clearly reproduced.

In the one-component developing system, a feed developing system (Japanese Patent Laid-Open No. 57-114163) is known as a method for achieving the reproducibility equivalent to that of the two-component developing system. Is a toner transport member that has a special structure in which a dielectric layer is provided on a conductive support, and a large number of microelectrodes insulated from each other are arranged on the surface of the conductive support to improve the reproducibility of fine lines. To improve.

It is also known that, by applying the volume electric resistance component of about 10 ⁷ Ωcm to the developing sleeve according to the same idea, it is possible to perform development with a similar edge effect. However, in the case of using the developer carrying member whose surface has a continuous insulating property or a high resistance value as described above,
As illustrated by the line c in FIG. 3B, the developing characteristic in the solid portion developing is gradually lowered, and even if a certain appropriate developing bias potential is applied, the high contrast required by the printer or the like is obtained. The problem that the image is not reproduced occurs.
In FIG. 3B, the line d is the developing characteristic in the line portion developing.

Therefore, in the present invention, a thin layer of charged developer is formed on the surface of a developer carrier, and the thin layer of the developer is carried on the surface of the electrostatic latent image carrier by the movement of the surface of the carrier. It is a one-component developing device that supplies a latent image and visualizes it, and maintains a solid solid image, which is an advantage of the one-component developing device, and uses the edge effect to fine line images, general line images and small images. It is an object of the present invention to provide a one-component developing device that can reproduce a point image more clearly.

[0011]

According to the present invention, according to the above object, a thin layer of a charged developer is formed on the surface of a developer carrier, and the thin layer of the developer is electrostatically latentized by moving the surface of the carrier. In a one-component developing device for supplying an electrostatic latent image on the surface of an image carrier to visualize it, at least the surface layer of the developer carrier is composed of a dielectric layer containing a conductive member, The members are continuous in a certain direction except the moving direction of the surface of the developer carrier, and are arranged alternately with the dielectric in the moving direction of the surface of the developer carrier, and a developing bias can be applied. The developer carrier is driven so that the surface moving speed of the developer carrier is different from the surface moving speed of the electrostatic latent image carrier.

It is considered that the resistance of the dielectric portion (insulating portion) constituting the surface layer portion is 10 ⁶ Ωcm or more, and the conductivity in the direction of the conductive member is 10 ⁴ Ωcm or less. The conductive member may be exposed on the surface of the developer carrying member or may be slightly buried from the surface.
In short, it is preferable that the conductive member is contained so as to exhibit the function of the conductive developer carrier in all or a part of the conductive member.

In order to apply a developing bias to the conductive member, the member is electrically connected to a conductive portion inside the surface layer of the developer carrying member, It is conceivable that the end surface is exposed to the end surface of the carrier so that a developing bias can be applied at least in the developing region through the exposed portion. In this case, it is not always necessary that all the conductive members are connected to the conductive portion inside the surface layer portion or that all the conductive members are exposed to the end surface of the carrier.

Various materials can be considered as the conductive member. As a specific example, in the production of the resin sleeve, a carbon fiber (long fiber) oriented resin composite material (prepreg) manufactured by Mitsubishi Kasei Co., Ltd. is used. Can be considered.
A prepreg is a sheet made by orienting and curing carbon fibers with an epoxy resin as a binder.It shows extremely good conductivity in the fiber orientation direction, but in the direction perpendicular to this it becomes a binder resin. It shows a close resistance value. Therefore, it is considered that this sheet is formed into a tube shape and used as a developing sleeve or a developing roller.

[0015]

According to the developing device of the present invention, a thin layer of the charged developer is formed and carried on the surface of the developer carrier, and is conveyed to the developing area by the movement of the surface of the carrier, where the surface of the electrostatic latent image carrier is carried. The electrostatic latent image is developed and the latent image is visualized. On the surface layer of the developer carrying member, conductive members are continuously arranged in a constant direction except the moving direction of the surface of the carrying member and are alternately arranged with dielectrics in the moving direction of the surface of the carrying member. Is applied, a part of the conductive member exerts the function of a conductive developer carrying member that makes the developing characteristics of the solid image good, and enables the reproduction of a hard solid image, while the dielectric material. The part of gives the edge effect to the line image, and makes it possible to reproduce a clear line image.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is an overall sectional view of a one-component developing apparatus which is an embodiment of the present invention. The developing device 10 includes a toner storage tank 11 that stores a toner 1 that is a one-component developer.
And a stirring member 12 which is rotationally driven counterclockwise in the drawing by a driving means (not shown).
A developing sleeve 13 corresponding to the surface layer of the toner carrier 130 is arranged in the opening of the toner storage tank 11, and an electrostatic latent image carrier (typically a photoconductor drum) P in a printer or the like is provided.
It comes in contact with C.

In the developing sleeve 13, a driving roller 15 made of conductive foamed silicone rubber, EPDM, aluminum roller or the like is arranged, and a developing bias is applied from the inside by a power source 17. There is. The driving roller 15 is rotationally driven in the clockwise direction in the drawing by a driving means (not shown). Although the shape and the setting position are not limited to those shown in the drawing, the toner storage tank 11 is provided with a regulation member 16 whose upper end is cantilevered by the toner storage tank 11, and the developing sleeve 13 has a regulation member 16 of about 3.5 g / mm. Are in contact with each other.

The regulating member 16 frictionally charges the toner 1 agitated and supplied by the agitating member 12 from the toner storage tank 11 to form a constant toner layer thickness on the surface of the developing sleeve 13. In this embodiment, the restriction member 16 is SUS30.
Although a stainless steel plate made of 1 steel plate was used, the material is not limited to this, and a phosphor bronze plate, rubber,
Various materials such as resin can be used.

Toner 1 is a negatively chargeable toner, and specifically, bisphenol A type polyester resin (AV: 1
9, OHV: 23, softening point 123 ° C, Tg: 65 ° C) 1
00 parts by weight, carbon black MA # 8 (manufactured by Mitsubishi Kasei Co., Ltd.) 5 parts by weight, Bontron S-34 (manufactured by Orient Chemical Industry Co., Ltd.) 3 parts by weight, and Viscole T
A composition comprising 2.5 parts by weight of S-200 (manufactured by Sanyo Kasei Co., Ltd.) was kneaded by a method known per se,
80% by weight in the range of 7 to 13 μm after pulverization and classification
Dispersed toner particles having an average particle diameter of 10 μm were manufactured, and hydrophobic silica (Talanox 500 manufactured by Tarco Co., Ltd.) was added to the toner particles in an amount of 0.5% by weight as a fluidizing agent. It was mixed and stirred for a minute.

As shown in FIG. 2, in the developing sleeve 13, an epoxy resin (dielectric) is used as a binder 13a, and carbon fibers 13b are oriented in one direction and cured to form a sheet. Resin composite material, specifically U
D tape prepreg hy-E ^R 10714AC (manufactured by Mitsubishi Kasei Co., Ltd., fiber compounding ratio 60%) was molded into a tube shape and used.

The binder is not limited to the epoxy resin, but polyester, phenol,
Thermosetting resin such as polyimide and bismaleide, PEE
Various kinds of thermoplastic resins such as K can be used. Further, the chargeability of the toner can be adjusted by selecting this binder. The blended fiber is not limited to carbon fiber, and any compound having conductivity can be used.
In this example, the carbon fibers were molded so as to be oriented in the sleeve longitudinal direction (rotational axis direction). However, the long fiber direction is not limited to this, and it can be oriented in any direction from the sleeve longitudinal direction to the rotational direction, such as 0 °, 30 °, 45 °, etc. when viewed from the sleeve longitudinal direction. It is possible. However, the rotation direction itself is excluded.

Further, since the distance between the fibers can be adjusted by adjusting the filling amount of the fibers, it is possible to adjust the resistance value (insulating property or high resistance). The molded sleeve 13 has a film thickness of about 160 μm, and the volume resistivity is 10 ⁰ Ω · cm or less in the fiber direction and 1 in the direction perpendicular thereto.
It was 0 ⁶ Ω · cm or more. In the present embodiment, the carbon fiber blending ratio was 60% and the film thickness was about 160 μm, but this value can be set quite freely, which allows control of mechanical properties and adjustment of electrical anisotropy. Is also possible. The resistance is measured by the Japan Rubber Association standard, SRI.
It was carried out according to the Wheatstone method of S2301.

More specifically, the developing sleeve 13 in this embodiment is adjusted in surface roughness Rz of the outer peripheral surface to about 5 μm by sandblasting, and the surface hardness of the obtained developing sleeve 13 is JIS K. It was 9H according to the pencil scratch test defined by 5400.
Such a developing device is mounted on a small laser beam printer having a system speed of 35 mm / sec, the developing sleeve is driven at θ (developing sleeve peripheral speed / photosensitive drum peripheral speed) = 2.5, and the developing sleeve 13 is exposed to light. In the developing area in contact with the body PC, the toner 1 existing on the surface of the developing sleeve 13 was made to adhere to the electrostatic latent image on the photoconductor to visualize the latent image. The toner image on the photoconductor thus obtained is transferred onto a transfer sheet conveyed from a transfer sheet supply unit (not shown), fixed by a fixing device (not shown), and then discharged as an image.

When the electrostatic latent image formed on the photosensitive layer on the surface of the photosensitive member is a line image, since the resin portion 13a (resistive component) exists in the developing sleeve 13, the lines of electric force generated from the latent image. Bends at the edges and emphasizes the electric field to obtain a print image with high density even when the original image density is low. If the electrostatic latent image is a solid image,
The development was rate-controlled by the conductive component in the developing sleeve 13, that is, the characteristics of the carbon fiber 13b portion, and a black solid image having a high contrast was obtained as in the case of using the conductive sleeve. (Second Embodiment) Next, another embodiment will be described.

In the second embodiment, as the developing sleeve, a tube is made by using the epoxy resin used in the above-mentioned first embodiment in which carbon fiber is oriented 30%, and the developing sleeve is used. The same device configuration was used, and the same experiment and evaluation as in Example 1 were performed. The developing sleeve manufactured at this time has a thickness of about 160 μm and an outer diameter of about 2 μm.
The surface resistivity Rz was 5 mm, the surface roughness Rz was about 5 μm, and the volume resistivity was 10 ⁰ Ω · cm or less in the fiber direction, 10 ⁶ Ω · cm or more in the direction perpendicular thereto, and the surface hardness was 9H or more.

Also in this embodiment, a sharp line image can be reproduced due to the edge effect, and in the solid part development, a hard and clear black solid image peculiar to the one-component developing device was obtained. (Comparative Example 1) Instead of the developing sleeve of Example 1,
Example 1 except that a tube was made using only carbon black and nylon 12 and used as the developing sleeve 13.
The same apparatus configuration was adopted and the same experiment and evaluation were performed. The developing sleeve manufactured at this time has a thickness of about 160.
μm, outer diameter about 25 mm, surface roughness Rz of the outer peripheral surface is about 5 μm
The volume resistivity was 10 ⁷ Ω · cm, and the surface hardness was B at m.

When such a high-resistance developing sleeve is used, a sharp line image can be reproduced due to the edge effect as described at the beginning, but the developing characteristics in solid part development are gentle. I fell asleep and could not reproduce a high contrast image without applying a fairly high developing bias potential. (Comparative Example 2) Instead of the developing sleeve of Example 1,
The same experiment and evaluation were carried out by employing the same apparatus configuration as in Example 1 except that Ni was used to produce a tube by electroforming and the developing sleeve 13 was used. The developing sleeve produced at this time has a thickness of about 35 μm, an outer diameter of about 25 mm,
Surface roughness of the outer peripheral surface is about 1.5 μm, surface hardness 9H
That was all.

When such a conductive developing sleeve was used, a solid black image was obtained as a solid image as described at the beginning. However, in the case of a fine line such as 1 dot line, the line is It wasn't reproduced clearly and faded. The present invention is not limited to the above-mentioned embodiments, but can be applied to any developing device of a one-component contact type.

For example, a developing sleeve having an inner diameter slightly larger than the outer diameter of the developing roller is fitted onto the driving roller, the developing sleeve is pressed against the driving roller from one side, and a slack portion formed on the opposite side is electrostatic latent image carrier. It can also be applied to a developing device that is brought into contact with.

[0030]

According to the present invention, a thin layer of a charged developer is formed on the surface of a developer carrier, and the thin layer of the developer is carried on the surface of the electrostatic latent image carrier by moving the surface of the carrier. A one-component developing device that supplies an electrostatic latent image and visualizes it
It is possible to provide a one-component developing device capable of maintaining a hard solid image, which is an advantage of the one-component developing device, and more clearly reproducing a thin line image, a general line image or a dot image by the edge effect.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a perspective view of a toner carrier of the developing device of FIG.

FIG. 3 is a graph showing developing characteristics of a developing device.
Figure (A) shows the developing characteristics of a conventional one-component developing apparatus, Figure (B) shows the developing characteristics of another conventional one-component developing apparatus, and Figure (C) shows the developing characteristics of a conventional two-component developing apparatus. Is.

[Explanation of symbols]

 10 developing device 1 toner 11 toner container 130 toner carrier 13 developing sleeve 15 driving roller 16 regulating member 17 developing bias power supply PC photoconductor drum

Claims (1)

[Claims] 1. A thin layer of a charged developer is formed on the surface of a developer carrier, and the thin layer of the developer is carried to form an electrostatic latent image on the surface of the electrostatic latent image carrier by moving the surface of the carrier. In a one-component developing device for supplying and visualizing this, at least the surface layer portion of the developer carrying member is composed of a dielectric layer containing a conductive member, and the conductive member moves on the surface of the developer carrying member. The developer carrying member is included so as to be continuously arranged in a fixed direction except the direction, and to be alternately arranged with the dielectric in the moving direction of the surface of the developer carrying member, and to be able to apply the developing bias. The developing device, wherein the body is driven so that its surface moving speed is different from the surface moving speed of the electrostatic latent image carrier.