JPS6095467A - Preventing method of deterioration of electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent an image from becoming out of focus during continuous copying operation by holding the surface of an electrophotographic sensitive body which uses amorphous silicon (a-Si) for a photoconductive layer at high temperatures within a specific temperature range during a copying process. CONSTITUTION:A barrier layer is provided on a conductive base when necessary, an a-Si photoconductive layer is formed thereupon by doping B, halogen, etc., and a surface barrier layer is formed on the photoconductive layer when necessary to form a photosensitive body. This photosensitive body, e.g. electrophotogtaphic sensitive drum 1 is held at 40-60 deg. surface temperature during the copying process, and a surface thermometer 11, infrared-ray heater 12, and temperature controller 13 are arranged in front of, for example, a corona electrifier 2. Consequently, active species of NOx, etc., generated by the corona electrifier on the surface of the photosensitive body and water in air are made easy to separate even when stuck on the surface to eliminate an out-of- focus image dur to a decrease in resolving power and a decrease in image density caused by the dispersion of charges distributed on the surface in an image pattern resulting from the sticking of NOx, water, etc. Thus, an out-of-focus state, specially, in a high-temperature and high-humidity atmosphere is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic photoreceptor. More specifically, the present invention relates to a method for maintaining the performance of an electrophotographic photoreceptor using amorphous silicon as a photoconductive material.

Conventionally, electrophotographic photoreceptors include Se, CdS, and ZnO.
Single-layer type or laminated type organic photoconductive materials using organic semiconductors such as polyvinyl carbazole are widely used. However, in recent years, when amorphous silicon semiconductors (hereinafter abbreviated as a-3T semiconductors) are used as photoconductive materials, compared to the case where conventionally widely used photoconductive materials such as those mentioned above are used, It is highly likely to have excellent performance in terms of mechanical durability, heat resistance, moisture resistance, corona ion resistance, etc.
In addition, since it is completely non-toxic, active development has been carried out to apply it to photoreceptors for electrophotography.
59).

As a result of these development studies, it has become possible to use the Habo A-3i semiconductor as a photoconductive layer in electrophotographic photoreceptors, but the corona resistance is not sufficient and it is equivalent to the temperature in summer in Japan. When continuous copying is performed in an environment where the image quality is 30°C and a relative temperature of about 85%, the resolution decreases and image blurring occurs, and this tendency is particularly noticeable when negative corona discharge is used. There were drawbacks.

Therefore, the first object of the present invention is to improve the performance of an electrophotographic photoreceptor using an a-3T semiconductor as a photoconductive layer, so as to prevent blurring of copied images even during continuous copying under high temperature and high humidity conditions. An object of the present invention is to provide a method for preventing the deterioration of.

A second object of the present invention is to provide an electrophotographic process that can withstand continuous copying under high temperature and high humidity using an electrophotographic photoreceptor using an a-3l semiconductor as a photoconductive layer.

This object of the present invention was easily achieved by maintaining the surface of an electrophotographic photoreceptor using an a-3l semiconductor as a photoconductive layer at a high temperature during the copying process.

In the a-3i semiconductor used in the present invention, when focusing on a single St ring atom, the atoms are arranged in a certain order in the vicinity of that atom, but do not have long-range order, which is the so-called non-regular structure. means crystalline silicon semiconductor. a-3i like this
Generally, a semiconductor thin film can be easily obtained by a known method such as a glow discharge method, a sputtering method, a CVD method, or an ion blating method.

Among these methods, it is particularly convenient to use the glow discharge method or the CVD method for the photoreceptor used in the present invention. , trisilane, tetrasilane, silicoethylene, silicoacetylene, disiloxane, silylamine, monochlorosilane, dichlorosilane, trichlorosilane, tetrachlorosilane, hexachlorodisilane, octachlortrisilane, decachlortetrasilane, dodecachlorpentasilane, monofluor Silane, dibromosilane, trifluorosilane, tetrafluorosilane, hexafluorodisilane, octafluorotrisilane, monobromosilane, dibromosilane,
Tribromosilane, tetrabromosilane, hexabromodisilane, octabromotrisilane, monoiodosilane, short silane, triiodosilane, tetraiodosilane, hexaiododisilane, octaiodotrisilane, and Compounds containing halogen atoms on the sides (e.g. 5iBrCI13, sicβ2F2
) etc.

These compounds can be used alone or in combination, and if necessary, hydrogen gas or the like can also be used in combination.

The a-3i layer used in the present invention is preferably doped with impurities to ensure sufficient performance as an electrophotographic photoreceptor. Such impurities include, for example, H
, FSC, N, O, and elements of Group V B of the Periodic Table of Elements,
In addition, elements of Group V B of the Periodic Table of Elements can be used, and these can be introduced into the a-31 layer by a known method.

In the present invention, "using an RA-3I semiconductor as a photoconductive layer" does not mean only when using an RA-3I semiconductor as a single layer; It also includes the case where a PN layer is formed, or the case where an organic or inorganic charge carrier transport layer is provided on the a-51 layer (as described in JP-A-54-116930).

Further, the "electrophotographic photoreceptor using the RA-3L semiconductor of the present invention as a photoconductive layer" is applicable not only when a photoconductive layer is simply provided on a conductive support, but also when a photoconductive layer and a conductive support are provided. If a barrier layer is provided between and/or on the surface of the photoconductive layer on the opposite side to prevent charge flow and improve charging, or to prevent abrasion of the photoreceptor. It also includes the case where the photoreceptor is provided with a protective layer, other anti-reflection layer, etc.

Regarding the insulating layers that act as barrier layers, protective layers, etc., for example, U.S. Pat.
Publication No. 46-3.713, Publication No. 42-23,9
No. 10, No. 43-24.748, No. 42-1
It is described in JP-A No. 9,747, JP-A No. 36-4.121, JP-A-55-87154, JP-A No. 56-83748, and JP-A No. 57-115559.

The conductive support used in the present invention is, for example, glass,
For example, a metal such as Ni, /1,
It can be arbitrarily selected from a support on which a conductive layer is formed, such as an alloy such as nichrome, an inorganic oxide having conductivity such as tin oxide, or a plate, film, or foil made only of a conductive substance. .

Among electrophotographic photoreceptors made of these various materials, in the present invention, from the viewpoint of durability in particular, an amorphous silicon layer (a- (abbreviated as 3i+C), a photoreceptor having a structure in which an a''-5iiis as a photoconductive layer and an a-5t:0 layer as a surface barrier layer that also serves as a protective layer for the a-3t layer is preferable; The barrier layer and/or the surface barrier layer contains 1 to 50 atomic % of halogen atoms (abbreviated as a-3l:C:X, where X is a halogen atom and the atomic % is 100 atomic %).
XX/ represents (S l +C+X). ) is preferred. The carbon atoms contained in the barrier layer and/or the surface barrier layer are preferably about 5 to about 90 atom%, more preferably about 40 to about 60 atom% (in this case, the atom% is 100XC/(S) with or without impurities
(represented by l+C)). Further, when a halogen atom is contained, it is particularly preferable to contain a fluorine atom.

Such a barrier layer may, for example, contain a certain amount of a compound containing carbon atoms (preferably also containing halogen atoms, especially fluorine atoms) together with a silicon atom-containing compound as described above in the vacuum vessel. By introducing a certain amount and performing a glow discharge, it can be formed in a rich manner. Compounds containing carbon atoms used in this way include, for example, methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, ethylene, propylene, 1-butene, isobutylene, 1-pentene, Hydrocarbons having 1 to 5 carbon atoms such as 2-pentene, acetylene, methylacetylene, butyne, and methyl fluoride,
Ethyl fluoride, propyl fluoride, methyl chloride, ethyl chloride,
Methyl bromide, ethyl bromide, methyl iodide, methylene fluoride,
Examples include alkyl halides such as methylene chloride and hexafluoroethane, and among these, alkyl fluorides such as methylene fluoride and hexafluoroethane are particularly preferred. These compounds can be used alone or in any combination. In this case, depending on the mixing ratio of the silicon-containing compound and the carbon-containing compound, a-3t
Ratio of carbon atoms contained in the layer (or ratio of halogen atoms if a compound containing halogen atoms is used)
is determined.

In the present invention, in particular, the thickness of the barrier layer is about 0.00
5μ to about 0.3μ is preferable, and the thickness of the a-3 layer is about 5μ.
˜about 100μ.

However, even when using a photoreceptor that does not further provide the above-mentioned surface barrier layer on the surface of the a-3i photoconductive layer, the method of the present invention that maintains the surface temperature of the photoreceptor at a high temperature can reduce the temperature and humidity. This case is also a preferred embodiment of the present invention since it is possible to prevent deterioration of resolution and blur of the image due to continuous copying at the bottom, thereby simplifying the structure of the photoreceptor and reducing manufacturing costs.

Generally, in an electrophotographic process, charging, exposure, development, and cleaning are repeated as a set. In this case, if the initial charge is positive, a negative charging process is incorporated during cleaning, and if the initial charge is negative, a positive charging process is incorporated during cleaning. , the residual charge is usually erased.

When the photoreceptor used in the present invention is a photoreceptor that utilizes an a-3T semiconductor as a photoconductive layer, it generally lacks durability against corona discharge, particularly in environments where negative corona discharge occurs in high temperature and humidity. This tendency is remarkable at the bottom, resulting in a decrease in resolution and blurring of the image. The cause of this is not necessarily clear, but considering that there are no abnormalities in the initial charge amount and sensitivity, it is assumed that active species such as NOx generated by corona discharge adhere to the surface of the photoreceptor, and that air (Although moisture inside may also be involved), it is also thought to be due to increasing electrical conductivity in the direction of the surface of the photoreceptor.

That is, it is understood that due to the imagewise exposure that follows charging, the charges that should have been distributed in an imagewise manner are dispersed on the surface of the photoreceptor, resulting in a decrease in resolution and a decrease in image density, resulting in image blurring.

In the present invention, since the surface temperature of the photoreceptor is maintained at a high temperature, even if active species such as the aforementioned NOx and moisture in the air are once attached to the photoreceptor, they are easily desorbed again, and substantially It is understood that the absolute amount of these active species adhering to the surface of the photoreceptor, which causes deterioration of the photoreceptor, is reduced, and this effect is thought to prevent image blurring even in continuous copying under high temperature and humidity.

The heating effect of the present invention is different from the case of erasing residual charges, and is particularly effective when the surface of the photoreceptor is an a-3i layer. Therefore, it is understood that the temperature of the surface of the photoreceptor to be heated needs to be higher than the activation energy required for the active species that degrade the photoreceptor to desorb from the surface of the photoreceptor. An electrophotographic photoreceptor using an a-5i semiconductor as a photoconductive layer, wherein the surface of the photoreceptor is an a-3i layer or an a-3i layer containing carbon atoms and/or halogen atoms as impurities.
In the case of a layer, image blurring occurs even if the surface of the photoreceptor is heated to 35°C, and a clear effect is only observed at 40°C or higher.

However, heating the photoreceptor surface more than necessary (for example, 100°C or more) is not only uneconomical but also undesirable because the developing toner fuses to the photoreceptor surface. It is sufficient to heat it to about 60°C.

In the present invention, the surface of the photoreceptor can be heated directly with, for example, infrared rays, or can also be heated from the support side of the photoreceptor with a heater and/or infrared rays. When heating is performed using a contact heater, it is necessary to arrange the heater so that it can heat the entire photoreceptor, but when heating is performed non-contact using infrared rays, etc., a portion of the rotating photoreceptor is heated. It is also possible to adopt a method of heating. In this case, the heating step may be added to any part of the image forming process of charging, exposure, development, transfer, and cleaning, but in order to make the device compact, it is best to apply the heating process to the photoreceptor immediately before charging. Therefore, it is preferable to heat immediately before charging. Such an image forming process is illustrated, for example, by FIG.

Although the method of the present invention is extremely simple, it is highly effective in maintaining the image quality of electrophotography, and can prevent a decrease in resolution and image blurring even under severe conditions. .

This method is of great significance because it makes it possible to actually use a photoreceptor using an a-3i semiconductor as a photoconductive layer by a simple method.

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 Using a Pelger-type glow discharge device for manufacturing amorphous silicon, which is equipped with a vacuum system, a gas supply piping system, a gas leak system, a heater, a glow discharge device, etc., light was sequentially applied onto a conductive support. a-3i layer and a-3i of conductive layer
:C barrier layer was formed.

Aluminum drum with polished surface (support: outer diameter 1
20 mm, length 410 mm) is set on the quartz plate on the rotating support inside the Pel Jar, the inside of the Pel Jar is evacuated, and the gas piping system provided with the Pel Jar is also evacuated. The degree of vacuum is approximately 3XIO-5Torr (
mHg).

Next, the aluminum drum was heated while controlling the temperature to 250° C. using a heater provided inside the Pelger. The temperature was controlled while measuring the temperature of the drum with an alumel-chromel thermocouple.

Next, the leak pulp was slightly opened, the vacuum level inside the Pel jar was adjusted to about 0.3 Torr, and a negative pulsating high voltage power source (hereinafter abbreviated as high voltage power source) was used to connect the aluminum drum and gas blowing plate. A glow discharge of 30 W was performed for 5 minutes between the drum and the gas adsorbed on the surface of the drum.

After turning off the high-voltage power supply and closing the leak valve, the inside of the Pelger was again brought to a vacuum level of about 1X105 Torr.

Then B2H15/H2 with 290 vol ppm hydrogen dilution
(hereinafter abbreviated as B7H5/H2) from the gas supply piping system while adjusting the flow rate with a mass flow meter.
/min (SCCM). Further, the valve of the SiH4 gas supply piping system was gradually opened, and the gas was supplied at a flow rate of 150 cc/min while adjusting the flow rate with a mass flow meter. In this operation, the pressure inside the Pelger was adjusted to 4.5xlO-'Torr by adjusting the bypass valve.

When the flow rate of the supplied gas became constant, glow discharge was performed between the rotating drum and the gas blowing plate at an input power of 100 W for 5 hours to form an amorphous silicon photoconductive layer.

Next, before starting the formation of the barrier layer, the gas supply piping system is closed and the vacuum inside the Pelger is set to 1 × 10 5 Torr.
I made it.

When the degree of vacuum inside the Pel Jar reached 1X10 5 Tor, adjust the mass flow meter of the SiH4 gas supply piping system to 30 cc/min and the mass flow meter of the C2F5 gas supply piping system to 8 cc/min, and add these to the Pel Jar. Next, when the degree of vacuum inside the Pelger reached 5X10-3 Torr, the mass flow meter of the SiH4 gas supply piping system was
The mass flow meter of the C2F5 gas supply piping system was adjusted to 32 cc/min. When the flow rates of these gases reached the set values, the pressure inside the Pelger was set to 4.5 x 10-' Torr using a bypass valve.

Next, a glow discharge was performed for 6 minutes with an input power of 100 W using a high voltage power supply to form a barrier layer.

After the high-voltage power supply was turned off and the glow discharge was terminated, when the pressure inside the Pelger reached 5×10 2 Torr, the vacuum level was further increased to 1×10 5 Torr and evacuation was performed for 10 minutes. Next, turn off the heater and bring the temperature of the drum to 1.
After waiting for the temperature to reach 00°C, the drum was taken out from inside the Pelger.

The total thickness of the amorphous silicon layer formed on the D drum is 37 μm, of which the barrier layer is about 0.21 μm.
Met. The carbon atomic ratio in this barrier layer was approximately 30 atomic percent.

For the electrophotographic photoreceptor obtained as described above,
Corona discharge was performed at an applied voltage of plus 6 kV for a charging time of 0.08 seconds, and immediately image exposure was performed at 1.degree. 5 lux.seconds. Next, a developer consisting of negatively charged toner and carrier was placed on the surface of the photoreceptor drum using a magnetic brush method, and transferred onto transfer paper by positive corona discharge to obtain a copy image.

Next, to clean the remaining toner, the applied voltage is reduced by minus 5. '
After corona charging was performed at 5 kV for a charging time of 0.08 seconds, the surface of the photoreceptor was cleaned with a cleaning blade. This image forming process is referred to as (A). When all steps of this image forming process (A) were performed 3000 times in an environment of a temperature of 30° C. and a relative humidity of 85%, significant blurring occurred in the copied image.

6 On the other hand, in the image forming process (A), after toner cleaning, a process was added in which a 200W infrared lamp was attached and the photoconductor was heated while controlling the surface temperature of the photoconductor to be maintained at 40°C. B).

Naturally, the surface of the photoreceptor was kept at 40° C. throughout this process (from charging to toner cleaning).

Using this process (B), when copies were made 3000 times in an environment with a temperature of 30°C and a relative humidity of 85%, the resulting copied images were clear and the resolution was 5 to 6 J! It was p/fashion.

Furthermore, after 50,000 copies were made under this environment, the resulting copied images were clear and had a resolution of 5 to 61p/1m.
It was demonstrated that process (B) is extremely superior.

Example 2゜Using the photoreceptor produced by the method of Example 1,
Except that the photoreceptor surface temperature in process B) was 50°C.
In exactly the same manner as in Example 1, results similar to those in Example 1 were obtained.

Example 3 Even when the surface of the photoreceptor in Example 2 was set at 60° C. and the number of copies was repeated 70,000 times, neither image blurring nor reduction in resolution occurred.

These results demonstrated that the method of the present invention is extremely effective in preventing deterioration of photoreceptors using a-31.

[Brief explanation of the drawing]

FIG. 1 is an example of an image forming process according to the present invention. In the figure, 1 is a photosensitive drum using a-3t, 2 is a corona charging device for image formation, 3 is an image exposure device, 4 is a toner developing device using a magnetic brush method, 5 is a pre-transfer lamp, 6
is a transfer paper, 7 is a corona charging device for transfer, 8 is a corona charging device for peeling the paper from the drum, 9 is a corona charging device for pre-cleaning, 10 is a cleaning blade, 11 is a surface temperature needle, 12 is an infrared ray Heater 13 represents a temperature control device. 9 1st part 2

Claims (1)

[Claims] 1) A method for preventing performance deterioration due to continuous use of an electrophotographic photoreceptor using amorphous silicon as a photoconductive layer, characterized by maintaining the surface temperature of the photoreceptor at a high temperature. A method for preventing deterioration of an electrophotographic photoreceptor. 2) The method for preventing deterioration of an electrophotographic photoreceptor according to claim 1, which comprises maintaining the surface temperature of the photoreceptor at 40''C to 60C.