JPS61133948A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent uneven density of an image due to light interference by laminating the first and the second amorphous surface layers each having a specified optical band gap and contg. carbon as a constituent element on an amorphous silicon photoconductive layer. CONSTITUTION:The photoconductive layer 15 made of amorphous Si is formed on an Al conductive substrate 4, and it has an optical band gap of about 1.62-1.70eV. The first and the second amorphous surface layers 16, 17 each having an optical band gap of 1.65-2.00, and 1.85-2.80eV, respectively, and each made of Si contg. carbon are laminated on the layer 15, thus permitting the reflected lights of irradiated laser beams with the interlayers between each layer 17, 16, 15 to be lowered, and electrophotographic characteristics to be enhanced without increasing manufacturing steps, by laminating only the first and second surface layers made of amorphous Si cong. carbon.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electrophotographic photoreceptor used, for example, in a button such as a radar printer.

[Technical background of the invention and its problems]

Conventionally, electrophotographic photoreceptors include selenium, selenium/arsenic, selenium/tellurium, cadmium sulfide resin dispersion,
Organic photoconductive materials have been used, but in recent years, amorphous silicon (hereinafter referred to as 1-81) has attracted attention.
The A-81 electrophotographic photoreceptor using this material is harmless, has no concern about pollution, can withstand high operating temperatures, has a high surface hardness, and is easy to handle. Due to its sensitivity, demand for commercialization is rapidly increasing.

On the other hand, in recent years, fax machines and word processors have become popular.

Electrophotographic printers using photoreceptors have been developed for terminals such as computers, combinations, etc., and various types of light sources are used in these printers. Among them, an electrophotographic laser printer that uses a radar as a light source uses He-Ne as the laser light source.
Gas radars such as t-rays have been used, but recently semiconductor radars have come to be mainly used because of the smaller size of printers, lower costs, and ease of modulation.

By the way, when trying to use A-81 as a photoreceptor in an electrophotographic laser printer that uses a semiconductor laser as a light source, the emission wavelength of semiconductor lasers is currently about 780 nm, and A-81 The photoreceptor has a rather low photosensitivity in the emission wavelength range of this semiconductor radar, and a clear image may not be obtained. Therefore, in order to have sufficient photosensitivity even at the emission wavelength of a semiconductor laser, G was added to the A-81 photoreceptor.

(rumanium) is often used to reduce the size of the optical band gear.

In addition, the hydrogen content of the photoconductive layer during a-8t exposure,
By lowering the optical band gear, it is also possible to lower the optical band gear and increase the long wavelength sensitivity.

However, using the above a-81 photoreceptor,
When we line-scan the radar light with a radar printer using a semiconductor radar as the light source and form an image,
Density unevenness like interference fringes may appear overlapping the character image. Further, this density unevenness can be eliminated by increasing the exposure amount of the radar, but even in that case, the character image will be left blank in places in the form of white streaks, making it impossible to obtain a good image. Furthermore, even if it does not appear in a character image, density unevenness due to interference fringes may appear in halftones when halftones are taken.

The reason for this is that the laser beam reflected on the surface of the A-81 photoreceptor, transmitted through the inside of the A-8T photoreceptor, reflected on the conductive substrate, specifically the surface of the aluminum tube, and then emitted from the surface again. This is because interference occurs between the reflected laser beam and the reflected laser beam. In the case of the A-81 photoreceptor, the photoconductive layer formed on the AA tube has some unevenness in film thickness, and this causes a difference in optical path length on the drum that causes interference. Hail. The interference effect between the reflected light from the surface of the A-81 photoconductor and the reflected light that is reflected from the surface of the At blank tube and then emitted from the surface is actually incident on the inside of the A-81 photoconductor. However, if the amount of carriers generated is not substantially limited, concentration unevenness will appear corresponding to the unevenness of the film thickness, as described above. Therefore, as a countermeasure,
It is sufficient to reduce the intensity of either of the reflected lights, and generally the surface of the At element tube is appropriately roughened or an antireflection film is provided on the surface.

When using 1-81 in an electrophotographic photoreceptor, the dark resistance of a-81 itself is approximately 10Ω·cm, so in order to increase the surface charge retention ability, it is generally used on a conductive substrate. A so-called laminated structure is adopted in which a blocking layer is provided to prevent charge injection from a conductive substrate, and a surface layer for charge retention is further provided on top of the photoconductive layer.

Therefore, when the surface of the At base tube is roughened as a countermeasure against the interference fringes described above for the a-8i photosensitive light of such a laminated structure, the narrowly spaced interference fringes corresponding to the uneven thickness of the photoconductive layer disappear, but Widely spaced interference fringes may appear in halftone images. This is due to the interference effect corresponding to the thickness unevenness of the surface layer.

Therefore, in order to eliminate these widely spaced interference fringes, it is sufficient to uniformly form a surface layer with a thickness that satisfies the anti-reflection conditions. However, if the surface layer is so thin that uniform film formation is impossible, the interference effect can be prevented by providing an antireflection film on top of the surface layer.

As mentioned above, the interference fringes that appear in radar printers can be solved by various methods, but when considering the simplification, labor saving, and productivity of the manufacturing process of the A-81 photoreceptor, it is possible to solve them as much as possible. It is better to finally manufacture the A-81 photoreceptor only with the membrane device and not add another manufacturing process. Therefore, it is disadvantageous to form an antireflection coating using a material having a refractive index compatible with A-81.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and an object of the present invention is to provide an electrophotographic photoreceptor that can prevent the occurrence of image density unevenness due to interference effects without increasing the number of manufacturing processes. It is about providing.

[Summary of the invention]

In order to achieve the above object, the present invention provides an electrophotographic photoreceptor in which a photoconductive layer made of an amorphous material containing silicon atoms as a matrix is provided on a conductive substrate. , optical band gear, 1.65 to 2.00 m
A first surface layer made of an amorphous material containing carbon as a constituent element and having an optical band gap of 1.85 to 2.80 eV is provided on the first surface layer.
The invention is characterized in that it has a second surface layer made of an amorphous material containing carbon as a constituent element.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 3 shows a film forming apparatus for forming a film on an electrophotographic photoreceptor according to the present invention, and numeral 1 in the figure is a reaction vessel. Inside this, there is an electrode 2 for applying high frequency power, a support stand 3 provided opposite to this and grounded, and a conductive substrate for film formation (conductive substrate) 4 provided on the upper part of this support stand 3. , and a heater 5 provided at the bottom of the support stand 3. The electrode 2 is insulated from the reaction vessel 1 with an insulating material 6 such as a thermal conductor, and a matching ♂ consisting of an LC circuit for matching high frequency power is installed outside the reaction vessel 1.
It is connected via the network 1 to a high frequency power source 8 for supplying power having a frequency for performing plasma discharge decomposition. In addition, 9 is a fee fs, for example, 5IH4,5
An f-s introduction pipe for introducing 12H6 gas, etc., 1
0 is the first pump which evacuates the inside of the reaction vessel 1 by a diffusion pump.
11 is a mechanical booster 4/f during film formation.
The second exhaust system, 12, 13, and 14, is pulp.

Next, an electrophotographic photoreceptor according to the present invention manufactured using the film forming apparatus described above is schematically shown in FIGS. 1 and 2.

In the electrophotographic photoreceptor shown in FIG. 1, a photoconductive layer 15 made of an amorphous material containing silicon atoms as a matrix is provided on top of a cylindrical conductive substrate 4 made of At. This photoconductive layer 15 is formed by plasma discharge decomposition using a gas such as 5tH4, St□H6, etc. When forming the film, in addition to the above-mentioned silicon-containing gas, the purpose is to increase the resistivity of the film. It is also common to form a film by mixing a gas containing an element of group mA of the periodic table.

Note that this photoconductive layer 15 has an optical band gap of 1.
．． 62 to 1.70 eV], and the film thickness was 10 to 7
Good electrophotographic properties can be obtained when the thickness is 0 μm, preferably 15 to 40 μm.

Further, on the top of the photoconductive layer 15, a first surface layer 16 is formed.
and second surface layer 12 are laminated in this order. The first surface layer 16 is formed by a plasma discharge decomposition method by mixing a gas containing silicon atoms as a matrix, such as 5tH4zS i 2H6, and a gas containing carbon, such as CH4, C2f (4, etc.), The second surface layer 17 is formed by the same method as the first surface layer 16, and has an optical band gap of 1.65 to 2.00eV. The first surface layer 16 has a thickness of 100X to 5 μm, preferably 5001 to 3 μm.

Further, the second surface layer 17 has a film thickness of 100X to 3 μm1.
Preferably it is 500X to 2 μm.

According to the above structure, by providing the first surface layer 16 and the second surface layer 17 on the top of the photoconductive layer 15, the radar light incident on the surface of the electrophotographic photoreceptor is transmitted to the second surface. When partially reflected by layer 17 and entering the interior, second surface layer 1
By setting the optical bandgap and film thickness of layer 7 to the above values, reflection of radar light at second surface layer 17 can be reduced. Furthermore, the second surface layer 11
The radar light incident on the inside reaches the first surface layer 16, but here too, by setting the optical pad gap and film thickness of the first surface layer 16, as described above,
Reflection of laser light on the first surface layer 16 can also be reduced. Next, the radar light transmitted through the first surface layer 16 reaches the surface of the photoconductive layer 150, but here, the optical band gear f of the photoconductive layer 15 and the optical band ear of the first surface layer 16 are By setting the optical band gear, f, of the photoconductive layer 15 so that , f do not change significantly, reflection on the surface of the photoconductive layer 15 can also be reduced.

That is, the second surface layer 1
7 suppresses the reflection of radar light, and furthermore, the interface between the second surface layer 17 and the first surface layer 16, the first surface layer 1
By suppressing the reflection of the radar light at the interface between the photoconductive layer 6 and the photoconductive layer 15, interference effects between the reflected radar lights can be prevented. Further, by laminating the first surface layer 16 and the second surface layer 12, it is possible to provide an electrophotographic photoreceptor having excellent charging ability, and excellent corona ion resistance, ozone resistance, and environment resistance. Can be done.

Further, in the electrophotographic photoreceptor shown in FIG. 2, the photoconductive layer 15
, the first surface layer 16, and the second surface layer 17 are similar to those of the electrophotographic photoreceptor shown in FIG. A blocking layer 18 is provided between the photoconductive layer 15 and the photoconductive layer 15 .

〔Concrete example〕

At as the conductive substrate 4 which has been thoroughly cleaned and dried
The raw tube 4 was placed in the vacuum container 1, and the inside of the vacuum container 1 was evacuated using a mechanical gas pump fK. At the same time, the heater 5 for heating the At blank tube 4 was turned on, the set temperature was set to 300° C., and heating was performed. After about 1 hour, the temperature of the At blank tube 4 stabilized at 300°C. Further, the degree of vacuum in the vacuum container 1 was 1.2×10 −5 Torr.

Next, in order to form the first layer 18, the flow rate of SiH4 was set at 300 maaM.

The flow rate ratio of B2H6 to eta4 is 5xlO, CH4
The flow rate ratio for 5in4 is 20ch, Al f 7 f!
200@ear of gas were introduced into the vacuum vessel 1, each regulated by a mass 70 controller, and maintained in that state for about 10 minutes. After confirming that the flow rate of the removal gas is stable for about 10 minutes, turn on the high frequency power supply 8 with a frequency of 13.56 MHz and turn on the high frequency power to 200 MHz.
W was applied to perform blow discharge. Note that the reaction pressure at this time was Q, 3 Torr. Further, the film forming time in this case was 10 minutes, and the film thickness of a separately formed film was measured to be 1.5 μm.

After forming the first blocking layer 18, all gases were stopped and the gas inside the vacuum container 1 was vented for 15 minutes. After that, the flow rate of 8*H4 was set to 600 sccM, and the flow rate of Alco medium bus was set to 500 secM.

The flow rate ratio of B2H6 to SiH4 was adjusted to 1×10 using a mass flow controller, and the flow rate was approximately 10
It was held in that state for a minute. After confirming that the flow rate of the removed gas was stable for about 10 minutes, the high frequency power was set to 400 W and glow discharge was performed. Note that the reaction pressure in this case was 1.4 Torr. As a result, the second photoconductive layer 15 was formed with a thickness of 35 μm by film formation for 2 hours. This photoconductive layer 15 had an optical band value of 1.63·V.

After forming this photoconductive layer 15, stop all gases,
The gas in the vacuum container 2 was flushed for 15 minutes. After that, in order to form the first surface layer 16, the flow rate of 5ta4 was set to 1008 ead, and the flow rate of CH4 was set to 300 sec.
After adjusting to M, the condition was maintained for about 10 minutes. After the flow rate of each gas was stabilized, the high frequency power was set to 150 W and glow discharge was performed. In addition, the reaction pressure in this case is 9.6
It was Torr. The film forming time was 15 minutes, and the film thickness was 0.8 μm. Further, the optical pan gear was 1.77·V.

After forming the first surface layer 16, the flow rate of CH4 was increased to 4
After increasing the flow rate to 50 aeeM and maintaining that state for about 10 minutes to stabilize the flow rate, the high frequency power was set to 150 W and the second surface layer 11 was formed.

The reaction pressure in this case was 0.68 Torr. Further, the film forming time was 3 minutes, and the film thickness was about 6,501 mm.

Further, the optical band gap was 2.0 eV.

After forming the second surface layer 17, the heating heater 5 is turned off, all gases are stopped, and the gas is injected for 20 minutes.
The drum (photoreceptor) on which the film was formed is cooled, and after the temperature drops to below 100°C, the nitrogen gas and equipment are stopped, and the drum (photoreceptor) is cooled.
(Photoreceptor) was taken out.

When the electrophotographic photoreceptor obtained in step 5 was evaluated using an evaluation device, the surface potential was 535 V.

Retention rate after 15 seconds: 72chi, half-decreased exposure: 0.51u4se
c, good electrophotographic properties were obtained with a residual potential of 12V. Furthermore, when an image was scanned using a radar printer equipped with a semiconductor radar with an oscillation wavelength of 790 nm, a good image with no density unevenness due to interference was obtained in both character images and halftones.

〔Effect of the invention〕

As explained above, according to the present invention, on a conductive substrate,
In an electrophotographic photoreceptor provided with a photoconductive layer made of an amorphous material containing silicon atoms as a matrix, an optical pan P gear and a g are in the range of 1.65 to 200 mV on the photoconductive layer. , a first surface layer made of an amorphous material containing carbon as a constituent element, and an optical band gap of 1.8.
Since the second surface layer made of an amorphous material having a voltage in the range of 5 to 2.80 V and containing carbon as a constituent element was laminated in this order, the manufacturing process required only the A-81 film formation process. This provides excellent effects such as being able to prevent the occurrence of density unevenness in images due to interference effects without increasing the electrophotographic properties or deteriorating the electrophotographic characteristics.

[Brief explanation of drawings]

1 and 2 are schematic configuration diagrams showing an electrophotographic photoreceptor according to the present invention, and FIG. 3 is a schematic configuration diagram showing a film forming apparatus for forming a film on the electrophotographic photoreceptor according to the present invention. It is a diagram.・Breath... Conductive substrate (conductive base), 15... Photoconductive layer, 16... First surface layer, 17... Second surface layer O

Claims (1)

[Claims] In an electrophotographic photoreceptor in which a photoconductive layer made of an amorphous material containing silicon atoms as a matrix is provided on a conductive substrate, an optical band gap of 1.65 is provided on the photoconductive layer.
A first surface layer made of an amorphous material having an optical band gap of 1.85 to 2.80 eV and comprising carbon as a constituent element; An electrophotographic photoreceptor characterized in that a second surface layer made of an amorphous material containing as an element is laminated in this order.