JPS62175779A - Electrophotographic device using amorphous silicon - Google Patents

Abstract

PURPOSE:To prevent the surface of an amorphous silicon photoconductor from deteriorating and to improve its brush resistance by employing a non-corona type electrostatic charging electrode contact system for all electrostatic charging mechanisms and using a conductive rubber roller for electrostatic charging as a main electrostatic charging mechanism. CONSTITUTION:A constant voltage based on the conductive substrate 1 of a photosensitive body is applied to the peripheral surface 16 of the conductive rubber roller 15 for electrostatic charging and the roller peripheral surface 16 and photoconductor layer 2 are pressed against each other to supply an electrostatic charge of the constant voltage to the surface of the photoconductor layer 2 uniformly. A toner image formed on the surface of the photoconductive layer 2 by a developing device 8 is transferred to transfer paper 14 on a non- corona basis. Thus, the non-corona type electrostatic charging electrode contact system is employed for all charging mechanisms, and consequently there is neither the surface deterioration of the photosensitive layer nor the formation of a hydrophilic surface because no discharge product such as ozone and nitrogen oxide is formed, thereby improving the brush resistance of the photosensitive body greatly.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electrophotographic device using an amorphous silicon-based photoconductor. The present invention relates to an electrophotographic device which is prevented from causing image deletion at high humidity and whose printing durability is significantly improved.

(Prior Art) Amorphous silicon-based photoconductor layers have high surface hardness, are sensitive to light on the long wavelength side, and have good sensitivity, so they are attracting attention as photoconductors for electrophotography. ing.

In FIG. 2 showing a conventional electrophotographic apparatus, an amorphous silicon-based photoconductor layer 2 is provided on the surface of a metal P ram 1 that is driven and rotated. Around this drum 1, a main charging corona charger (positive charging type) 3; an image exposure mechanism consisting of a run f4, a document support transparent plate 5, and an optical system 6; a developing mechanism 8 having toner 7; a toner transfer corona Charger (positive charging type) 9; corona charger 10 for paper separation;
A static elimination rung 11; and a cleaning mechanism 12 are provided in this order.

First, the photoconductor layer 2 is charged with a positive charge using the corona charger 3. Next, the original 1 to be copied is displayed using the lamp 4.
3 is illuminated, and the photoconductor layer 2 is exposed to a light beam image of the original through an optical system 6, thereby forming an electrostatic latent image corresponding to the original image. This electrostatic latent image is developed with toner 7 by a developing mechanism 8. The transfer paper 14 is supplied so as to be in contact with the drum surface at the position of the toner transfer charger 9, and a positive corona charge with the same polarity as the electrostatic image is performed from the back side of the transfer paper 14.
The toner image is transferred onto transfer paper 14. The transfer paper 14 on which the toner image has been transferred is transferred to the AC of the separation corona charter 10.
It is electrostatically stripped from the drum by neutralization and sent to a processing area such as a fusing area (not shown).

After the toner has been transferred, the photoconductor layer 2 is exposed entirely to light by a charge eliminating rung 11 to erase residual charges, and then a cleaning mechanism 12 removes the residual toner.

(Problems to be Solved by the Invention) However, a photoreceptor having an amorphous silicon-based photoconductor layer on a conductive substrate requires repeated copying processes such as charging, image exposure, development, and transfer.・Causes surface deterioration.
The drawbacks are that image deletion occurs at high humidity during long-term use, and the printing durability of the photoreceptor is still generally low.

The reason for this is that corona discharge is used to charge the photoreceptor, which generates ozone, which oxidizes the surface of the photoreceptor, or that nitrogen in the air is oxidized and this nitrogen oxidation occurs. This is thought to be due to substances adhering to the surface of the photoreceptor, making the surface hydrophilic.

Such a phenomenon is unique to amorphous silicon photoconductors and has not been observed in conventional photoconductors. This is because amorphous selenium-based photoreceptors and organic photoreceptors have relatively soft surfaces, and surface deterioration may be formed on the photoreceptor due to friction with the cleaning grade or rubbing with the developing magnetic brush. This is because, whereas this part is scraped, such a scraping effect cannot be expected with an amorphous silicon-based photoreceptor having a high surface hardness.

Therefore, the technical problem of the present invention is to prevent surface deterioration of an amorphous silicon photoconductor, and to significantly improve its printing durability without causing image deletion at high humidity. We are in the process of providing equipment.

(Means for Solving the Problems) The present invention provides an electrophotographic photoreceptor having an amorphous silicon-based photoconductor layer on a conductive substrate, and a main charger disposed along a travel path of the photoreceptor. In an electrophotographic apparatus consisting of an image exposure mechanism, a developing mechanism, and a transfer mechanism, all charging mechanisms are of a non-corona type charging electrode contact type, and the main charging mechanism is an amorphous silicon photoconductor layer and a surface contact type. It is characterized by the use of a contacting conductive charging roller.

(Function) In FIG. 1 showing the schematic layout of the electrophotographic apparatus of the present invention, members common to each member of the conventional apparatus shown in FIG. 2 are indicated by common side illumination numerals. First, in the apparatus of the present invention, all charging mechanisms are of a non-corona charging electrode contact type. The charging electrode dissolution method refers to a method in which a charging electrode, which is a conductor, contacts a layer to be charged to perform charging.

In the present invention, a charging conductive rubber roller 15 is used in place of the main charging corona charger 3 shown in FIG.

The conductive rubber roller 15 has a circumferential surface 16 that is pressed against the surface of the drum photoconductor layer 2, and the circumferential surface 16 is connected to a main charging power source 18 through a connection 17. Thus, a constant voltage is applied to the circumferential surface 16 of the electrically conductive rubber charging roller 15 with respect to the electrically conductive substrate 1 of the photoreceptor), due to the pressure contact between the roller surface 16 and the photoconductor layer 2). , electrostatic charges of a constant voltage are uniformly supplied to the surface of the photoconductor layer 2.

In this apparatus, a photoconductor layer 20 is developed by a developing mechanism 8.
Transfer of the toner image formed on the surface to the transfer paper 14 is also performed in a non-corona method. That is, in the transfer area, a transfer roller electrode 19 is arranged so as to be in pressure contact with the surface of the photoconductor layer 20 having the toner image via the transfer paper 14, and this roller electrode 19 is connected to the surface of the photoconductor layer 20 having the toner image. 20 is connected to a transfer power source 21. As a result, the back and surface of the transfer paper 14 are charged by the roller electrode 19 so as to have the same polarity as the charge on the photoconductor layer 2, and the toner image is transferred.

Further, the transfer paper 14 on which the toner has been transferred is separated from the photoreceptor drum using the curvature of the photoreceptor drum.
This is easily accomplished by using a mechanical separation mechanism such as 2.

According to the present invention, since all the charging mechanisms in the electrophotographic apparatus are of a non-corona charging electrode contact type, discharge products such as ozone and nitrogen oxides are not generated.
There is no surface deterioration of the photosensitive layer or formation of a hydrophilic surface, and the printing durability of the photosensitive member can be significantly improved. Further, there is no dew condensation on the surface of the photosensitive layer at high temperatures, no image deletion occurs, and the use of a drum heater, which has conventionally been necessary to prevent this, can be omitted.

In the present invention, performing the main charging by pressing the surface of the conductive rubber solder 2 brings particular advantages in relation to the use of an amorphous silicon-based photoconductor layer as a photoreceptor. That is, the amorphous silicon photoreceptor has a higher capacitance than other photoreceptors, such as selenium photoreceptors and organic photoreceptors, and as a result, the transfer of charge to the surface due to pressure contact with the electrode is difficult. This has the advantage that injection can be easily performed.

Furthermore, the conductive demler used in the present invention is in close contact with the surface of the photoreceptor with virtually no air gap due to its elasticity or gas ductility, making it easy to transfer or inject charges to the surface of the photoreceptor. It will be held in Further, since the photosensitive drum and the electrode are gradually separated along their peripheries, it is possible to smoothly separate the photoreceptor drum and the electrode without any troubles such as discharge.

(Example) In the present invention, any known amorphous silicon photoconductor layer 2 may be used. For example, amorphous silicon deposited on a substrate by plasma decomposition of silane gas or the like may be used. This stuff is doped with hydrogen, halogen, etc. It may be doped with Group I or Group V elemental ice of the periodic table, such as ron or phosphorus.

The physical properties of a typical amorphous silicon photoreceptor include dark conductivity <10 Ω・α and activation energy <0.
．． s s sV, photoconductivity) 10-'Ω-1・α-1
, an optical band gear, the voltage is 1.7 to 1.9 eV, the amount of bonded hydrogen is 5 to 20 atoms, and the dielectric constant of the film is in the range of 11.5 to 12.5. .

This amorphous silicon photoconductive layer can be glass-charged or negatively charged depending on the doping species.

As the conductive im-roller 15, a roller made of a known conductive rubber can be used. The conductive rubber may be any material as long as it has both the elasticity inherent in rubber and the pressurized conductive function, such as silicon rubber, polyurethane, fluorine rubber, styrene-butadiene, nitrile-butadiene, polybutadiene,
Polyisoprene, butyldim, ethylene-propyleneim, chloroglene rubber K, various conductive agents such as conductive Kagen powder, various metal powders or particles, conductive zinc oxide powder, conductive tin oxide powder, conductive titanium oxide powder, etc. A powder conductive agent or a fibrous conductive agent such as carden fiber, metal fiber, or metallized organic fiber is blended to impart conductivity.

A suitable conductive roller may include one in which conductive fibers are embedded in a polyurethane disstomer. Embedding conductive fibers in the polyurethane disstomer provides significant advantages for the mechanical and electrical properties of the roller.

In other words, as a method of imparting conductivity to a nidistomer, it is known to mix conductive pigments such as the previously mentioned pigments, carbon black, metal powder, etc. In this method, in order to reduce the electrical resistance of the shellastomer to a satisfactory level, it is necessary to incorporate a large amount of pigment, and due to the orientation of such a large amount of pigment, the desirable physical properties of the shellastomer are lost. , the disadvantage is that the rollers are hard and brittle.

On the other hand, according to this aspect of the present invention, when embedding conductive fibers in the polyurethane distomer, excellent conductivity can be imparted to the surface of Row 2 with a significantly small amount of fibers, / +7 It does not lose any of the excellent elastic properties, flexibility or abrasion resistance of the cretan elastomer. Furthermore, since the conductive fiber used in this aspect of the present invention is extremely flexible, the exposed end portion thereof comes into good contact with the surface of the photoreceptor to form a stable conductive path. As the conductive fiber, it is best to use carden fiber from the viewpoint of ease of blending into polyurethane and various physical properties as a fiber. However, other fine metal fibers and various synthetic fibers treated with electrical conductivity can also be used.

As the polyurethane elastomer, polyurethane rubbers conventionally used in this field are used, generally poly9-rethane consisting of soft segments derived from polyester polyols or polyether polyols and hard segments derived from aromatic diisocyanates.

When blending or embedding conductive fibers in polyurethane elastomer, it is important that the fibers extend from the root to the tip of the row 2 to be formed, as described above. From the point of view, the conductive fibers are arranged in the form of multifilaments or spun yarns arranged in the radial direction and/or the circumferential direction so that the conductive fibers are distributed and located at least on the roller surface, or in the form of waeps, nonwoven fabrics, etc. of the fibers. It is used in the form of woven cloth, gauze, netting, etc., embedded in polyurethane nydistomer.

To embed conductive fibers in a polyurethane elastomer, wrap or a sheet of conductive fibers around a roller of the polyurethane elastomer, and heat the wrap or sheet into the polyurethane elastomer at a temperature above the melting point or softening point of the polyurethane elastomer. A method of embedding the conductive fiber in a mold, or a method of placing a conductive fiber cube or sheet in a mold and pouring the I-refrethane elastomer into the mold, etc., are employed. Although the amount used is larger than when using conductive fibers in the form of long fibers, it is possible to mix conductive fibers in the form of 7 leases or short fibers into polyurethane, and to create a matrix of short fibers in polyurethane. Conductivity can also be imparted by forming such a layer.

In order to improve the adhesion between the conductive fibers and the polyurethane elastomer, the fibers may be pretreated with a silane coupling agent or the like.

The amount of conductive fibers embedded in the polyurethane elastomer can vary widely within the range that imparts conductivity to the roller, but in general, one volume of polyurethane elastomer is 1 c.
The object of the present invention can be satisfied if the fiber content is 70 to 550 cm per comb.

The charging voltage applied to the conductive rubber roller may be such that the surface potential of the photoconductor layer is 200 to 500 volts, and for this purpose, the voltage applied to the blade should be 500 to 2000 volts. It is preferable to set it as N root. The contact pressure of the conductive rubber roll against the photoreceptor is preferably in the range of 0.5 to 2 kv'cm in terms of linear pressure (pressure per roll length).

The conductive rubber roller and the photosensitive drum may be brought into contact with each other substantially without slipping, that is, at the same speed, and with an electric current of 0.5 to 30 mA ec between the two.
It may be possible to make contact with each other so that there is a slight speed difference. Alternatively, the conductive roller may be actively driven,
It may be configured to follow the rotation of the photoreceptor drum.

In the present invention, image exposure uses a reso-diode, a light-emitting diode, a liquid crystal diode, etc., in addition to a copy exposure method that uses a light source, a lens, or a reflector to perform exposure using transmitted light or reflected light from an original. In the case of a laser diode, rotational scanning using a Holigan is performed. In addition, when the latter light emitting body is used, the exposure of the light image is performed under digital signal control, and the function as a printer is provided.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view illustrating the process of an electrophotographic apparatus according to the present invention, and FIG. 2 is a schematic sectional view illustrating the process of a conventional electrophotographic apparatus. 2...Amorphous silicon photoconductor layer 4...Rung 6...Optical system 8...Developing mechanism 12...Cleaning mechanism 15...Charging conductive rubber roller 19...Transfer Figure 1 Figure 2 Roller electrode for use

Claims (1)

[Claims] (1) An electrophotographic photoreceptor having an amorphous silicon-based photoconductor layer on a conductive substrate, and a main charging mechanism, image exposure mechanism, development mechanism, and transfer mechanism arranged along the movement path of the photoreceptor. In an electrophotographic apparatus, all charging mechanisms are of a non-corona type charging electrode contact type, and a charging conductive rubber roller in surface contact with an amorphous silicon-based photoconductor layer is used as the main charging mechanism. An electrophotographic device characterized by: