JPS62175781A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To prevent the surface of an amorphous silicon photoconductor from being deteriorated 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 blade for electrostatic charging as a main electrostatic charging mechanism. CONSTITUTION:The conductive rubber blade 15 has a tip part 16 which is pressed against the surface of a drum photoconductor layer 2 and the other end part is connected to a power source 18 for main electrostatic charging by a connection 17. A constant voltage based upon the conductive substrate 1 of a photosensitive body is applied to the tip 16 of the conductive rubber blade 15 for electrostatic charging and the blade tip 16 and photoconductor layer 2 move relatively to supply the electrostatic charge of the constant voltage to the surface of the photoconductor layer 2 uniformly. This device transfers a toner image to transfer paper 14 based on a non- corona system. The non-corona type electrostatic charging electrode contact system is employed for all electrostatic charging mechanisms of the electrophotographic device and then none of discharge products such as ozone and nitrogen oxide is generated, so there is neither the surface deterioration of the photosensitive layer nor the formation of a hydrophilic surface and the brush resistance of the photosensitive body is improved.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an electrophotographic device using an amorphous silicon-based photoconductor, and more specifically, the present invention relates to an electrophotographic device that uses an amorphous silicon-based photoconductor. The present invention relates to an electrophotographic device which has significantly improved printing durability without causing image deletion at high humidity.

(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. 3 showing a conventional electrophotographic apparatus, an amorphous silicon-based photoconductor layer 2 is provided on the surface of a metal drum 1 that is driven and rotated. Around this drum l, there are a main charging corona charger (positive charging type) 3; an image exposure mechanism consisting of a lamp 4, a document support transparent plate 5, and an optical system 6; a developing mechanism 8 having toner 7; and a toner transfer corona. Charger (positive charging type) 9; corona charger for paper separation 10;
A static elimination lamp 11 and a cleaning nog mechanism 12 are provided in this order.

First, the photoconductor J@2 is charged with a positive charge using the corona charger 3. Next, the original 13 to be copied is illuminated by the lamp 4, and the photoconductor layer 2 is exposed to a light beam image of the original through the 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 positively charged corona charging with the same polarity as the electrostatic image is performed from the back side of the transfer paper 14, so that the toner image is transferred to the transfer paper 14. to be transcribed. The transfer paper 14 on which the toner image has been transferred is transferred to A of the separation corona charger 10.
It is electrostatically peeled off from the drum by C static elimination, and the fixing area (
(not shown).

After the toner has been transferred, the photoconductor layer 2 is exposed to light from the entire surface of the photoconductor layer 2 to eliminate residual charges, and then the remaining toner is removed by the cleaning mechanism 12.

(Problems to be Solved by the Invention) However, a photoreceptor having an amorphous silicon-based photoconductor layer on a conductive substrate has problems with charging and image exposure.

Repetition of copying steps such as development and transfer causes surface deterioration, 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 oxidizes nitrogen in the air, and this nitrogen oxide is transferred to the photoreceptor. It is recognized that this is due to the fact that it adheres to the surface and the surface changes to become hydrophilic.

Such a phenomenon is unique to amorphous silicon photoconductors and has not been observed in conventional photoconductors. This is because the surface of amorphous seleno-based photoreceptors and organic photoreceptors is relatively soft, and surface degradation may be formed on the photoreceptor due to friction with the cleaning blade or rubbing with the developing magnetic brush. This is because, while this portion 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 a mechanism, an image exposure mechanism, a developing mechanism, and a transfer mechanism, all charging mechanisms are of a non-corona charging electrode contact type, and the main charging mechanism is an amorphous silicon-based photoconductor layer. It is characterized by the use of a charging conductive rubber blade whose tips come into contact.

The charging conductive rubber blade used in the present invention is preferably a conductive rubber blade in which abrasive particles are dispersed. (Function) In FIG. Components common to those of the conventional device shown in FIG. 3 are designated by common side numerals. First, in the apparatus of the present invention, all charging mechanisms are of a non-corona charging electrode contact type. The charging electrode contact method means 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 blade 15 is used in place of the main charging corona charger 3 shown in FIG. This conductive rubber blade 15 is connected to the drum photoconductor layer 20.
It has a tip 16 that is pressed against the surface, and the other end is connected to a main charging power source 18 through a wire 17.

Thus, a constant voltage is applied to the tip 16 of the conductive rubber blade 15 for charging with respect to the conductive substrate IK of the photoreceptor, and due to the relative movement between the blade tip 16 and the photoconductor layer 2, light is Electrostatic charges of a constant voltage are uniformly supplied to the surface of the conductor layer 2.

In this apparatus, the toner image formed on the surface of the photoconductor layer 2 by the developing mechanism 8 is also transferred to the transfer paper 14 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 transfer roller electrode 19 by a wire connection 20. It is connected to the power supply 21. As a result, the back surface of the transfer paper 14 is 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 type 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 humidity, no image deletion occurs, and the use of a drum heater, which is conventionally required to prevent this, can be omitted.

In the present invention, performing the main charging by pressing the tip of the conductive rubber blade brings additional advantages in addition to eliminating the disadvantages caused by corona charging.

That is, by applying pressure contact and sliding force to the surface of the photoreceptor during main charging, residual toner and photosensitive layer surface deterioration components adhering to the surface of the photosensitive layer can be effectively removed during charging. Removal of such deteriorating components is possible because the amorphous silicon-based photoconductor has extremely high hardness and does not wear itself out even with high pressure contact force. In addition, when a non-corona charging electrode contact method is applied to the photoconductor layer, if a toner film layer is formed on the guide layer, the area where this toner film layer is present will not conduct the photoconductor. As a result of the increased contact resistance between the body layer and the charged electrode,
The charging current decreases, and the surface of the photoconductor layer becomes insufficiently charged. However, in the method of the present invention, the toner film is effectively removed, so charging defects and charging unevenness do not occur. It will be effectively resolved. When abrasive particles are dispersed and present in the conductive rubber blade for charging, the above-mentioned effect is particularly effectively achieved.

(Operations and Effects of the Invention) According to the apparatus of the present invention described above, surface deterioration of the amorphous silicon photoconductor is effectively prevented, image deletion does not occur at high humidity, and its printing durability is significantly improved. In addition, since high voltage generation equipment is not required, it is possible to provide a copying machine or a splitter with significantly reduced costs.

(Example) In the present invention, as the amorphous silicon-based photoconductor layer 2, any known material can be used. This stuff is doped with hydrogen, halogens, etc., and then? It may be doped with an element of group 1 or group V of the periodic table, such as ron or phosphorus.

The physical properties of a typical amorphous silicon photoreceptor include dark conductivity (10Ω・α, activation energy <0.85
eV, photoconductivity) 10 Ω'cm, optical band gap 1.7 to 1.9 eV, the amount of bonded hydrogen is 5 to 20 atoms, and the dielectric constant of the film is 11.5 to 1.9 eV.
It is in the range of 12.5.

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

As the conductive rubber blade 15, a blade formed from a known conductive rubber can be used.

The conductive rubber may be any material as long as it has the inherent elasticity of rubber and the pressurized conductive function, such as silicone rubber, polyurethane rubber, fluororesin rubber, styrene-butadiene rubber, nitrile-butadiene rubber, polybutadiene, polyisoprene, Gutil rubber, ethylene-propylene rubber, chloroprene rubber, various conductive agents such as conductive carbon powder, various metal powders or particles, conductive zinc oxide powder, conductive tin oxide powder, conductive titanium oxide powder, etc. In addition, those which are blended with a fibrous conductive agent such as Kagen fiber, metal fiber, metal lysong organic fiber, etc. to impart conductivity are used.

As the abrasive compounded in the conductive rubber, silica powder, silica, corundum, boron nitride, boron carbide, silicon carbide, alumina abrasive, zirconia-alumina, etc. are used. It is preferable to use it in an amount of 15% by weight.

A suitable conductive rubber braid may include a polyurethane elastomer with conductive fibers embedded therein. Embedding conductive fibers in the polyurethane elastomer provides significant advantages for the mechanical and electrical properties of the blade. That is, as already pointed out, Kagen black is a method for imparting conductivity to elastomers.

It is known to blend conductive pigments such as metal powder, but this method of blending conductive pigments does not require the use of elastomers! ! In order to lower the resistance value to a satisfactory level, a large amount of pigment must be blended, and the desirable physical properties of an elastomer are lost due to the blending of such a large amount of pigment, making the grade hard and brittle. There is a drawback that. On the other hand, according to this aspect of the present invention, when embedding conductive fibers in a polyurethane elastomer, excellent conductivity can be imparted to the blade tip with a significantly small amount of fibers. It does not lose any of its excellent elastic properties, flexibility or abrasion resistance. Moreover, since the conductive fiber used in this aspect of the present invention is extremely flexible, a stable conductive path is formed even if the exposed end portion of the fiber comes into close contact with the surface of the photoreceptor. The blade extends from the tip to the root, so even if the blade tip wears out during long-term use, the conductive fibers will always be exposed at the tip, which has the advantage that its excellent conductivity will not be lost. . As the conductive fiber, it is best to use carbon 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, generally polyurethanes consisting of soft segments derived from polyester polyols or polyether polyols and hard segments derived from aromatic diisocyanates, are used.

When blending or embedding conductive fibers in a polyurethane distomer, as mentioned above, it is important to ensure that the fibers extend from the root to the tip of the elastic brake to be formed. From this point of view, multifilaments or spun yarns of conductive fibers are arranged in the width direction so that the conductive fibers are oriented in the above-mentioned direction of the blade.
Alternatively, the fibers may be used by being embedded in a polyurethane disstomer in the form of a web, nonwoven fabric, woven fabric, gauze, net, or the like.

To embed conductive fibers in a polyurethane elastomer, a sheet of polyurethane elastomer and a web or sheet of conductive fibers are layered and passed between rollers at a temperature above the melting point or softening point of the polyurethane elastomer. , a method of embedding the web or sheet in an elastomer, or a method of sandwiching a conductive fiber web or a seven-layer sandwich between two sheets of polyurethane entomer, and then crosslinking and integrating both sheets. A method is adopted in which a web or sheet of conductive fibers is placed in a mold, and a polyurethane elastomer is poured into the mold.

Although the amount used is larger than when conductive fibers are used in the form of long fibers, it is possible to mix conductive fibers in the form of 7 leases or short fibers into polyurethane. Conductivity can also be imparted by forming a matrix.

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

The amount of conductive fibers embedded in the polyurethane elastomer can be varied widely within the range that imparts conductivity to the blade tip, but is generally from 2 to 180 In9, particularly from 4 to 160 In9, per 1 crn area of the polyurethane elastomer.
114? The purpose of the present invention can be satisfied if the fibers of the present invention are contained.

The charging voltage applied to the conductive rubber blade may be such that the surface potential of the photoconductor layer is 200 to 500°.
0 to 2000. Preferably, it is t/rut. The contact pressure between the conductive rubber blade and the photoconductor, as a linear pressure (pressure per length of the blade), is generally in the range of 1 to 5 psi.

The contact between the conductive rubber blade and the photoconductor can be achieved by a countercurrent contact method in which the direction toward the tip 16 of the blade 15 and the direction of rotation of the photoconductor 20 face each other, as shown in FIG. As shown in FIG. 2-B, a co-current contact method may be adopted in which the direction of the blade 15 toward the tip 16 is along the rotational direction of the photoconductor 20, but the former method is preferable from the viewpoint of preventing discharge. Moreover, in the case of FIG. 2-A, it is generally desirable that the contact angle α between the two is within the range of 15 to 80 degrees.

In the present invention, image exposure includes an exposure method using a laser diode, a light emitting diode, a liquid crystal diode, etc., in addition to a copying exposure method that uses a light source, a lens, or a reflector to expose light by transmitted light or reflected light from an original. can also be used, and in the case of a laser diode, a rotation standard using a horigon is performed. In addition, when using the latter light emitter, the exposure of the light image is performed by digital signal control.
It is given the function of a printer.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view illustrating the process of the electrophotographic apparatus of the present invention. Figures 2-A and 2-B are diagrams for explaining the contact position of the conductive rubber blade of the electrophotographic apparatus of the present invention, and Figure 3 is a diagram for explaining the process of the conventional electrophotographic apparatus. be. 2... Amorphous silicon-based photoconductor layer, 4... Lamp, 6... Optical system, 8... Developing mechanism, 12... Ri I
J-ning mechanism, 15... Conductive rubber blade for charging, 19... Roller electrode for transfer.

Claims (2)

[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 the main charging mechanism is a charging conductive rubber blade whose tip is in contact with an amorphous silicon photoconductor layer. An electrophotographic device characterized in that it is used. (2) The device according to claim 1, wherein the conductive rubber blade for charging is a conductive rubber blade in which abrasive particles are dispersed.