JPS6022150A - Developing device - Google Patents

Abstract

PURPOSE:To enhance jumping efficiency of a devloper remarkably and stably, to enable development at low potential, and to obtain a high-quality image by illuminating the surface layer of the photosensitive body of a developing roller with a destaticizing lamp. CONSTITUTION:The layer (a') of a developer triboelectrified with a blade 35 is formed on a developing roller 33, and the photosensitive face 29 of a photosensitive body 13 is developed. At that time, bias voltage Vb is applied to control image quality. The roller 33 faces a destaticizing lamp 37, the photosensitive layer 32 of the roller 33 is made conductive with the light incident throught the layer (a'), and electrostatic charge induced on the surface in advance or caused there by friction is removed. In this case, when Se is used, it can be fully erased by irradiating the layer (a') with a light of about 50-100lux.sec.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electrostatic latent image developing device used, for example, in electrophotography.

[Technical background of the invention and its problems]

Conventionally, methods for developing electrostatic latent images include dry development methods such as magnetic brush development, cascade development, and fur brush development, and liquid development using electrophoresis, as well as various modifications. Many things are known, but relatively few have been put into practical use.

By the way, among the developing methods that have not been put to practical use, U.S. Patent No. 3,232,190 or U.S. Patent No. 3.99
The method disclosed in No. 7,688 and the like is being considered. That is, as shown in FIG. 10), an electrode 2 having a thin layer of non-magnetic developer a is placed opposite an electrostatic latent image holding surface J, which is a surface to be developed, in a non-contact state to form a latent image. This is a method of developing (hereinafter referred to as non-contact development) by causing the developer a to fly and adhere to the latent image area by electrostatic force using an electric field generated between , is very useful in color copying machines and the like that repeatedly perform development using multicolor developers.

However, in this non-contact development, there is no effective means for maintaining uniform charging and a predetermined charge amount necessary for selectively flying the developer a. Further, the electric field required to make the developer a fly is large, for example, the latent image holding surface 1
Even if the gap between the electrode 2 and the electrode 2 is made close to 150 μm, the potential of the latent image needs to be about 100V, and there are only a limited number of photoreceptors that can withstand this potential. Furthermore, even if an external bias is applied to reduce this problem, arc discharge may occur due to the proximity of the electrodes 2, damaging various parts, or fogging may occur due to uneven charging of the developer a. There is a problem that unevenness occurs.

Therefore, the following considerations were made. That is, the force that causes the developer a to fly can be obtained by using the developer a with different charge amounts, or by providing the dielectric layer 3 on the developing electrode 2 as shown in FIG. 1(c). As a result of examining the strength of the electric field necessary for flight, it was found that developer a and electrode 2 were separated due to the charge on the developer.
It turns out that it is the mirror image force that occurs between the two. This mirror image force Fm is expressed by the particle diameter of the developer a, or the development It changes in inverse proportion to the square of the distance between agent a and electrode 2. Therefore, the attraction force, that is, the flying force ED, of the developer a caused by the electric field E generated by the latent image in the gap in the development area is expressed as follows. When it is large and the amount of charge on both sides is small (the amount of charge when FD takes the maximum value), it is easiest to fly.

However, this value of q is actually several microphones I:I
Since it is a small value equivalent to the amount of charge on the order of /gram,
The production of the developer 1 is quite difficult, and it is particularly likely to produce particles having opposite polarity charging characteristics, making it practically difficult to solve the above-mentioned problems from the viewpoint of the developer a. Therefore, considering r, which is another factor, it is conceivable to move the developer a away from the electrode 2 (increase the distance R between the developer a and the electrode 2). As an example, as shown in FIG.
It is recognized that the mirror image force Fm can be rapidly reduced by providing the dielectric layer 3 of Im. However, the dielectric layer 3
As a result, frictional electrification with the developer cannot be avoided, and as a result, new electrostatic force interference occurs between the developer a and the dielectric layer 3, which seriously deteriorates the uniformity and stability of the image. It is highly unstable over time and in response to environmental conditions.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a developing device which has been developed based on the above-mentioned circumstances and is capable of developing an electrostatic latent image, thereby making it possible to obtain a higher quality image.

[Summary of the invention]

In the present invention, a layer of developer is formed on the surface of a conveying member, this layer is placed close to an electrostatic latent image holding surface, and the developer is selectively ejected by an electric field based on the electrostatic latent on this holding surface. In the developing device which develops the electrostatic latent image by
The transport member is characterized by comprising a photoconductive material layer formed on the surface portion of the conveying member, and a light irradiation means for irradiating the photoconductive material layer with light.

[Embodiments of the invention]

A first embodiment of the present invention will be described below with reference to FIGS. 2 to 4. FIG. 2 shows an electronic copying machine using a developing device according to the present invention, and numeral 11 in the figure is a main body. On the upper surface of this main body 11, there is provided a document placing table 12 that moves back and forth in accordance with the copying process, and a drum that rotates in synchronization with the reciprocating movement of the document placing table 12 is provided approximately inside the main body 1. A photoconductor 13 having a shape of 1.5 mm is pivotally supported. An exposure system 16 is provided between the photoreceptor 13 and the original table 12, and includes a light beam 14, a focusing light transmitter 15, etc., which irradiates the original on the document table 12 and reflects the light. Light is guided onto the photoreceptor 13 to form an original image. Further, around the photoreceptor 13, in order from the image forming position along the rotational direction of the photoreceptor 13, a developing device 17, a transfer device 18, a stripping device 19, a static eliminator 20, a cleaning device 21, a static eliminator 30, and a charging device are provided. A device 22 is arranged.

Further, at the bottom of the main body 1, there is provided a transfer path 23 for the transfer paper p passing between the photoreceptor J3, the transfer device 18, and the peeling device 19, and the base end thereof is connected to a paper feed guide 24 or an expansion paper feed path 23. It is connected to a paper feed section 26 that independently feeds paper from the cassette 25, and its end faces a paper discharge tray 28 via a fixing device 27.

Therefore, the photoreceptor 13 is made of amorphous selenium, silicon,
Selected from inorganic photoreceptors such as selenium and tellurium alloys, resin-dispersed photoreceptors such as zinc oxide and cadmium sulfide, and various organic photoreceptors, the photoreceptor surface, which is a static latent image holding surface, is first charged by the charging device 22. 29 is uniformly charged to about 500 to 800V. Next, the exposure system 16 forms an image of the document to form an electrostatic latent image. This electrostatic latent image is developed by the developing device 17, thereby forming a developer image. This developer image is transferred to the transfer paper p fed from the paper feed section 26.
This transfer paper p is peeled off from the photoreceptor 13 by a peeling device 19, fixed by a fixing device 27, and then discharged onto a paper discharge tray 28.

On the other hand, the developer a remaining on the photoreceptor 13 without being transferred is neutralized by the static eliminator 20 and then removed by the cleaning device 21. The static electricity is removed and the product is ready for reuse.

By the way, the developing device 17, as shown in FIG.
A developing roller as a conveyance member, which is formed by providing a photoreceptor layer 32 as a photoconductive material layer as described above with a thickness of about 10 μm on the surface of a cylindrical row 231 as a substrate made of a conductive material such as aluminum or brass. 33, and a developer (
Toner) a hopper 34 that supplies toner a, and this hopper 34
Urethane, which is brought into contact with the tip at an angle parallel to the developing roller 33, in order to coat the developer a supplied onto the developing roller 33 in a layer of uniform thickness.
Elastic blade 3 made of rubber material such as styrene butadiene or silicone, or plate material such as phosphor bronze or stainless steel
5, a voltage applying device 36 that applies a bias voltage between the developing roller 33 and the photoreceptor 13, and a static elimination lamp 37 that irradiates the photoreceptor layer 32 of the developing roller 33 with light.

The elastic blade 35 coats the developing roller 33 rotating in a predetermined direction with about 20 to 30
The developer layer a' of ttm is frictionally charged by contact with the blade 35 or the surface of the developing row 233, and is charged to a desired polarity, for example, negative polarity. This charged developer layer a' is applied to the photosensitive surface 29 of the photoreceptor 13 having a positive electrostatic latent image.
When the particles come close to each other by about 300 μm, they fly selectively based on the electric field generated between them and the latent images, and develop the latent images one after another. At this time, a good image can be obtained by applying an image control bias voltage (b) for promoting or inhibiting the flying of the developer (a).

The developing roller 33 that has passed through the developing area is moved by the static elimination lamp 37
The photoreceptor layer 32 is made conductive by the incident light that has passed through the developer layer a', and has been induced on the surface in advance.
Alternatively, static electricity generated by friction is eliminated. In this case, if the photoreceptor layer 32 uses selenium, the
It is possible to sufficiently eliminate the charge by irradiating light of about 0 tux, sec from above the developer layer a'.

According to the above configuration, since the surface of the developing roller 33 is the photoreceptor layer 32 and the photoreceptor layer 32 is irradiated with light by the static elimination run fsv, the developing roller 3 of the developer a
As shown in FIG.
Due to the intervention of 2, the flying characteristics of the very small developer a can be greatly improved using the same principle as in FIG. In this case, the smaller the frictional charge between the developer a and the photoreceptor layer 32 and the larger the frictional charge between the developer a and the elastic blade 35, the smaller the binding force of the developer a. This is because the Coulomb force depends on the distance between charges. Therefore, the flight sensitivity of the developer a can be stably and dramatically improved, making it possible to develop an electrostatic latent image at a much lower potential, resulting in a much higher quality image.

It should be noted that the present invention is not limited to the above-mentioned embodiment, and may be configured as shown in FIG. 5 or FIG. 6, for example. That is, in the second embodiment shown in FIG. 5, a transparent cylindrical row 238 as a substrate whose glass tube surface is conductively treated and a photoreceptor layer 39 as a photoconductive material layer provided on this surface are used.
A developing roller 4o is constructed as a conveying member, and a static elimination lamp 41 is disposed inside the developing roller 4o.With this construction, in addition to the effects of the first embodiment, the light transmission efficiency is improved. At the same time, it is possible to eliminate static electricity and prevent contamination of F41.

In this case, even with the same photoreceptor layer 32 as in the first embodiment, 5
Approximately 10 tux, sec was sufficient. Further, in the third embodiment shown in Figure 6 of the Imperial Rescript, a developing belt 44 as a conveying member is constituted by a conveying belt 42 as a substrate and a photoreceptor layer 43 as a photoconductive material layer provided on this side. A scraping blade 45 for peeling off the returning developer layer a' is brought into contact with this circumferential surface, and a charge eliminating lamp 46 is opposed to the downstream side thereof. In this configuration, the expensive transparent cylindrical roll 38 is used as in the second embodiment.
There is no need to use .

Furthermore, the photoreceptor layers 32 and 39 of the above embodiment.

43 uses the same photoreceptor used for image formation (2), but it can be used up to a low level of characteristics.This is not for directly forming images. However, it is sufficient to meet the minimum requirements for temporary conductivity.For this reason, when using relatively short f7 materials such as zinc oxide or phthalocyanate organic photoconductors, However, in addition to being usable for a long period of time, this type of coating liquid material can be mass-produced and is inexpensive.In addition, there is no noticeable effect when the layer thickness is between 10 and 50 μm, but when it is thicker, Since the residual potential becomes large, it is necessary to repeat trial production for each material used and select the appropriate thickness.Furthermore, in terms of materials, it is necessary to have a stable amount of charge on the developing roller 33, 40 or the developing belt 44. On the other hand, as a developer, the materials that have been used as two-component materials are used as they are, but the amount of additives (dyes such as glosine, pigments, etc.) to control the amount of charge and polarity is selected. The photoreceptor layers 32, 39, 43 on the surface of the developing roller 33, 40 or the developing belt 44 and the elastic blades S5, 3
It is necessary to adjust it according to the triboelectric charging property of 5.35.

Prediction of the amount of charge is currently difficult, and trial and error is required for each combination. In addition, developer a
Mechanically, it is also necessary to have excellent fluidity, and for this reason, spraying in hot air or adding silica powder are effective in making the developer a spherical. Further, the developing rollers 33, 40 and the developing belt 44 are connected to the photoreceptor layer 3.
The cylindrical row 231.3B serving as the base of 2, 39.43 or the base portion of the conveyor belt 42 is roughened by sand blasting or the like, so that the surface of the photoreceptor layer 32, 39.43 is
When processed to have a fine particle surface of about 2 μm, it becomes easier to form a more uniform layer and contributes to uniform image formation.

〔Effect of the invention〕

As explained above, according to the present invention, a developer layer is formed on the surface of the conveying member, this layer is placed close to and opposed to the electrostatic latent image holding surface, and an electric field based on the electrostatic latent image on the holding surface is formed. In the developing device which develops the electrostatic latent image by selectively flying the developer, a photoconductive material layer formed on the surface of the conveying member and a photoconductive material layer Since it is equipped with a light irradiation means that irradiates light, it dramatically and stably increases the flying efficiency of the developer, making it possible to develop an electrostatic latent image at a low potential in the body, resulting in a higher quality product. It has excellent effects such as being able to obtain images of

[Brief explanation of drawings]

Fig. 10)←)(c) is an explanatory diagram of the conventional operation, Figs. 2 to 4 show the first embodiment of the present invention, and Fig. 2 is a sectional view of the electronic copying machine; 3 is a sectional view of the developing device, FIG. 4 is an explanatory diagram of the operation, FIG. 5 is a sectional view showing a second embodiment of the invention, and FIG. 6 is a sectional view showing a third embodiment of the invention. It is. 17... Developing device, 29... Electrostatic latent image holding surface (photosensitive surface), a... Developer, 31... Substrate (cylindrical roller)
, 32... photoconductive material layer (photoreceptor layer), 33...
Conveying member (developing door), 37... Static elimination lamp, 38
... Substrate (transparent cylindrical roller), 39... Photoconductive material (photoreceptor layer), 40... Conveyance member (developing roller),
41... Static elimination lamp, 42... Board (transport belt)
, 43... photoconductive material layer (photoreceptor layer), 44...
Conveyance member (developing belt), 46... static elimination lamp. 1st v! J Figure 3 Figure 5 jt) Figure 6

Claims (1)

[Scope of Claims] (Li) A layer of developer is formed on the surface of the conveyance member, this layer is placed close to and opposed to the electrostatic latent image holding surface, and the developer is The electrostatic latent image is developed by selectively flying a photoconductive material layer formed on the surface of the conveying member, and a light beam that irradiates the photoconductive material layer with light. A developing device characterized by comprising an irradiation means. (2) The conveying member is constituted by forming a photoelectric material layer on the surface of a conductive substrate, and the photoconductive material layer has a substantially large friction with the developer. The developing device according to claim 1, which does not perform charging.