JPH0140985B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing device used for electrostatic recording.

Conventionally, developing methods used for this type of electrostatic recording can be broadly classified into dry developing methods and wet developing methods. Among the dry developing methods, there is a two-component developing method. In this two-component developing method, a carrier and toner are mixed to form a developer, the toner is charged, and development is achieved by charge balance with the electrostatic latent image. This is the way to do it. This method has good image quality, is most commonly used in low-speed to high-speed copying machines, and is technically established. However, a toner concentration control mechanism is required to maintain a constant mixing ratio of toner and carrier, and spent toner in the carrier generated by mixing toner and carrier causes the developer to reach the end of its lifespan, requiring periodic replacement. There are drawbacks such as: In addition, since the single-component development method does not use a carrier, there are no problems with toner concentration control or developer life, but the image quality is poor and the paper cannot be used unless it is treated with high resistance. , the paper that can be used is limited. On the other hand, the wet development method provides good image quality, but because it uses Isopar liquid, which is a petroleum-based solvent, it must be handled with great care. In addition, it is difficult to print with high density, and there is also the problem that paper must be selected.

The present invention solves the above problems by eliminating the need for toner concentration control, replenishing the developer regardless of its lifespan, and using non-hazardous or non-polluting water-soluble or organic solvents. To provide a liquid type developer which uses a developer to maintain an image quality equivalent to gravure printing and can print without processing paper, and which develops an electrostatic latent image. That is, in the present invention, a part of the sleeve is immersed in a conductive developer filled in a tank, and a cylindrical sleeve having a number of holes penetrating the inside and outside on the circumferential surface is rotatably installed, and the liquid level of the developer is adjusted. This developing device is characterized in that the circumferential surface of the sleeve exposed above faces the surface of the rotating photoreceptor without contacting it.

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

In FIG. 1, a charger 2 charges the surface of a photoreceptor 1, and an original 3 is transferred to an exposure system 4.
When exposed to light, a latent image of the original is formed on the surface of the photoreceptor. When the latent image passes through the developing device 5, developer droplets fly onto the photoreceptor 1 and adhere to the latent image on the surface of the photoreceptor 1, forming a visible image. On the other hand, Hotupa 6
The paper is fed in synchronization with the timing at which the paper is transferred by the transfer device 7. The paper is charged by the transfer device 7, and the visible image on the surface of the photoreceptor is transferred onto the paper.
Copying is complete. Since the visible image on the surface of the photoreceptor is not entirely transferred, it is cleaned by the cleaning mechanism 8. The charge remaining on the surface of the photoreceptor is removed by the neutralizing light of the static eliminator 9, and the electrophotographic process is completed.

FIG. 2 is a sectional view of the developing device 5 according to the present invention. That is, the present invention uses a conductive developer as a developer, and the developer 1 stored in the tank 10
1, an electrically conductive cylindrical rotating sleeve 12 having a number of holes 12a, ... which penetrate inside and outside, opened on the circumferential surface,
The lower circumferential surface thereof is immersed and arranged so as to be rotatable. Further, the upper circumferential surface of the rotating sleeve 12 exposed above the liquid surface is made to face the photoreceptor 1 without coming into contact with it, and the two are rotated at a relative speed.

FIG. 3 is a schematic diagram illustrating the principles of the invention. The photoreceptor 1 and the sleeve 12 are rotating at a relative speed. When the latent image on the surface of the photoreceptor 1 gradually approaches the sleeve 12, an electrostatic field acts between it and the sleeve 12, and the developer 11 held in the hole 12a by surface tension at the same potential as the sleeve 12 is electrostatically charged. Receive power. Furthermore, the gap between the two is shown in Figure 3b.
As it becomes narrower, the electrostatic force becomes stronger,
The developer 11 flies as droplets on the surface of the photoreceptor against viscosity, surface tension, and gravity, and a visible image is formed on the surface of the photoreceptor.

According to experiments, the circumferential speed of photoreceptor 1 was set at 3 cm to 100 cm.
cm/S, relative speed of sleeve 12 from 0.2 to
About 10 times, the gap with photoreceptor 1 is 0.1 to 1.5 mm,
Good images were obtained when the potential difference between the photoreceptor latent image and the sleeve was set to 100 V or more. Incidentally, a bias voltage V may be applied to the sleeve 12 to maintain the potential difference between the latent image on the photoreceptor and the sleeve.
Further, by varying the bias voltage V, the printing density can be varied. In addition, the developer 11
The viscosity is 0.5~75cps, the surface tension is 5~100dyne/
cm, the density does not matter much, about 1 g/cm ² , and the resistance value only needs to be electrically conductive, as long as it is about 10 ⁸ Ω-cm or less. Also, it may be either water-based or oil-based. If the viscosity of the developed image 11 is high, the development speed becomes slow, if the surface tension is low, it is difficult to obtain a sharp image, and if the viscosity is high, the potential difference between the photoreceptor and the sleeve becomes large. If the gap between the photoreceptor and the developing sleeve is small, a liquid flow will be formed on the photoreceptor, resulting in a trailing image, and if there is too much, the image will be disturbed. The smaller the diameter of the hole 12a of the sleeve 12, the better the image, but the developing speed tends to be slow. The size of the hole 12a is preferably 0.005 to 0.8 mmφ, and its shape does not necessarily have to be circular.
It may also be porous.

As described above, the present invention uses a conductive developer as the developer, rotates the sleeve and photoconductor at a relative speed, and attaches the developer to the photoconductor using electrostatic force, so there is no need to control sleeve density. At the same time, it is only necessary to replenish the developer, and it is possible to print with high quality images without having to process the paper. The sleeve used in the present invention has a cylindrical shape, and the hole opened in the sleeve is a through hole penetrating the inside and outside, so it is possible to capture a certain amount of liquid without creating bubbles just by immersing it in the liquid. Even when the photoreceptor is ejected onto a photoreceptor under electrostatic force, the photoreceptor can be ejected without being affected by negative pressure or the like. Therefore, replenishing liquid to the sleeve, maintaining and transporting the liquid, and supplying it to the photoreceptor can be done smoothly.
It can be done accurately and develops high-quality visible images. Furthermore, since the sleeve that holds the developer is rotated, it has an effect that can be applied to high-speed printing machines.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of a copying machine to which a developing device according to the present invention is applied, FIG. 2 is a sectional view of the developing device according to the present invention, and FIGS. 3 a and 3 are schematic diagrams showing the principle of the present invention. 1...Photoreceptor, 5...Developer, 10...Developer, 11
...Tank, 12...Sleeve, 12a...Sleeve hole.

Claims (1)

[Claims] 1 A part of the sleeve is immersed in a conductive developer filled in a tank, and a cylindrical sleeve having a number of holes penetrating the inside and outside on its circumferential surface is rotatably installed and exposed above the surface of the developer. A developing device characterized in that the circumferential surface of the sleeve faces the surface of a rotating photoreceptor without contacting it.