JPS62295063A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To form a high-quality initial image and to enhance stability against the lapse of time and printing resistance by forming a photoconductive layer composed essentially of amorphous silicon containing Ge, and the second surface layer containing nitrogen higher in concentration than N contained in the first surface layer. CONSTITUTION:The photoconductive layer 3 is formed on an electric charge injection blocking layer 2 formed on a substrate 1, the layer 3 is composed essentially of amorphous silicon containing Ge in at least one layer region of it, and the first surface layer 4 and the second surface layer 5 are composed essentially of amorphous silicon containing nitrogen in a concentration higher in the layer 5 than in the layer 4. It is preferred to control the nitrogen concentration of the layer 4 in the range of 10-100atom% of Si, and its film thickness in the range of 0.01-5mum. On the other hand, it is preferred to control the nitrogen concentration of the layer 5 in the range of 50-130atom% of Si, and its film thickness in the range of 0.01-5mum.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Field of Industrial Application The present invention relates to an electrophotographic photoreceptor containing amorphous silicon.

Conventional technology The future of electrophotographic photoreceptors is mainly due to deterioration in electrical characteristics,
It is known that this is controlled by factors such as the occurrence of scratches on the surface and changes in the quality of the photoreceptor material itself (especially thermal changes). In recent years, photoreceptors using materials mainly composed of amorphous silicon have been attracting attention because these materials have the potential to fundamentally eliminate the above-mentioned lifespan factors of conventional photoreceptors. I'll go. That is, the amorphous silicon material has stable repeatability in terms of electrical properties, high hardness and thermal stability, and has the potential to provide a photoreceptor with an extremely long life.

In addition, amorphous silicon not only has a long life expectancy, but also has high photosensitivity, and has the potential to be used in medium to high speed copying and printers.

Problems to be Solved by the Invention Amorphous silicon has great potential as a photoreceptor material, but it has dark resistance,
photosensitivity at long wavelengths, regional strength (especially ductility),
Environmental stability (temperature, humidity) for stability over time and image quality
It has problems with dependencies.

For example, although an amorphous silicon material does have high photosensitivity, its peak is around 700 nm, and a sharp drop in sensitivity is observed at wavelengths longer than that.

Therefore, when this material is applied to a photoreceptor for a printer using a semiconductor laser having a wavelength of about aoonm as a light source, the sensitivity is still insufficient. Also,
Since the relationship between sensitivity and wavelength has a steep slope in the vicinity of 800 nm, there is instability in that the effective sensitivity of the photoreceptor changes significantly due to variations in the manufacturing process of the photoreceptor or variations in the wavelength of the semiconductor laser. It is inherent.

Furthermore, although amorphous silicon materials do have high hardness and exhibit a Witzkers hardness of the order of 1000, materials with lower hardness (for example, the edges of copy paper or cleaning blades in copy machines, etc.) ) has the problem that the welded portion exhibits image omission when it comes into contact with the fused portion.

Generally speaking, when an amorphous silicon photoreceptor is repeatedly used in a copier (or printer) for a relatively long period of time,
This is known to cause a decrease in resolution (image blur). The cause of this is thought to be the attachment of foreign matter to the surface of the photoreceptor and/or deterioration of the photoreceptor itself.

In general, the image blurring phenomenon may occur not only due to the adhesion of foreign matter to the photoconductor or deterioration of its quality, but also due to structural reasons of the photoconductor (for example, the use of an inappropriate surface layer), or in this case, In this case, image deletion occurs at the initial stage, that is, within about one to several ten cycles.

The present invention aims to solve the problems of the amorphous silicon photoreceptor described above.

That is, an object of the present invention is to provide a high-quality initial image,
Another object of the present invention is to provide an electrophotographic photoreceptor that has excellent stability over time and printing durability.

Another object of the present invention is to provide an electrophotographic photoreceptor having high photosensitivity not only in the visible light region but also in the near-infrared region, which is the emission wavelength of a semiconductor laser.

Another object of the present invention is to provide an electrophotographic photoreceptor with high dark resistance and excellent charging ability.

Another object of the present invention is to provide a photoreceptor that is less dependent on the operating environment.

Another object of the present invention is to provide an electrophotographic photoreceptor that provides stable and high initial image quality in all usage environments and that does not deteriorate even after repeated use.

Means for Solving the Problems The above aspects of the present invention can be achieved by the following electrophotographic photoreceptor. That is, in the electrophotographic photoreceptor of the present invention, a groove is formed by sequentially laminating a photoconductive layer, a first surface layer, and a second surface layer on a support, and the photoconductive layer At least a part of the region is mainly composed of amorphous silicon doped with germanium atoms, and the first surface view and the second surface view are each mainly composed of amorphous silicon doped with nitrogen atoms. , and the nitrogen atom concentration in the second surface layer is higher than the nitrogen atom concentration in the first surface layer.

Hereinafter, the electrophotographic photoreceptor of the present invention will be described in detail with reference to the drawings.

1 to 3 are schematic diagrams each illustrating a typical structure of the electrophotographic photoreceptor of the present invention. In the figure, 1 is a support, 2 is a charge injection blocking layer, 3 is a photoconductive layer, 31 is a charge transport layer, 32 is a charge generation layer, and 4 and 5 are a first surface layer and a second surface, respectively. It is a layer.

The support 1 can be appropriately selected depending on the purpose, such as metals such as aluminum, nickel, chromium, and stainless steel, or plastic sheets with conductive films, glass, and paper.

Each of the layers 2 to 5 above is a layer mainly composed of amorphous silicon, and can be formed by a glow discharge decomposition method, a sputtering method, an ion blasting method, a vacuum evaporation method, or the like. Taking glow discharge decomposition as an example, the manufacturing method is as follows. First, as the raw material gas, a mixture of a main raw material gas containing silicon atoms and a raw material gas containing necessary additive atoms is used. In this case, if necessary, a carrier gas such as hydrogen gas or an inert gas may be mixed into this mixture. Taking AC discharge as an example, the film forming conditions are: frequency 50 Hz-5GH2, reactor internal pressure 10-4-5 Torr, discharge power 10-2000.
W, and the support temperature is 30-300°C. The thickness of each layer can be appropriately set by adjusting the discharge time. Further, as the main raw material gas containing silicon atoms, silanes, particularly SiH4 and/or Si2H6, are used.

The charge injection blocking layer 2 is made of amorphous silicon doped with a group Ⅰ element or a group V element. The amount of additives is 110-
A range of 5000 pp is preferred.

Further, the film thickness is preferably in the range of 0.01-5 μm.

Whether a Group Ⅰ element or a Group V element is used as an additive is determined by the charge sign of the photoreceptor.

For layer formation, diborane (B2H6) is typically used as a raw material gas containing Group I elements, and phosphine (PH3) is typically used as a raw material gas containing Group V elements.
is used. In addition to the Group I or Group V elements, other elements may be added to this charge injection blocking layer mainly composed of amorphous silicon for various purposes.

The photoconductive layer 3 is mainly made of amorphous silicon with germanium atoms added to at least a portion of its layer region.

The film thickness is preferably in the range of 1-100 μm. For layer formation, any source gas containing germanium atoms can be used as long as it contains germanium as a component and can be used in the gas phase, but germanium (G) is typically used.
eH4>gas is used. Further, as illustrated in FIGS. 2 and 3, this photoconductive layer is composed of two layers, a charge generation layer and a charge transport layer, for functional separation, thereby making the effect even more remarkable.

The charge transport layer 31 is mainly composed of amorphous silicon doped with a Group 1 element. The film thickness is preferably in the range of 1-100 μm. In layer formation, an element containing a group Ⅰ element: Y1
As for the dregs! Diborane is used in the 1'tl type. In addition, the amount of Group Ⅰ elements added is 0.11-1O0pp.
A range of is preferred.

The charge generation layer 32 is mainly composed of amorphous silicon doped with germanium atoms. Film thickness is 0. A range of 1-10 μm is desirable. In addition, the amount of germanium atoms added is
The atomic ratio to silicon atoms is preferably in the range of 0.1-1.5.

Atoms other than those mentioned above may be added to the photoconductive layer 3 mainly composed of amorphous silicon, or to the charge generation layer 32 and charge transport layer 31 that constitute it, for various purposes. It is.

The surface layers 4 and 5 are mainly composed of amorphous silicon doped with nitrogen atoms. For layer formation, nitrogen atoms can be used as a raw material gas containing nitrogen atoms (any single substance or compound that can be used as a constituent element in the gas phase can be used, but for example, N2 gas or RuihaNH3
, N2H4, HN3, etc. can be mentioned. The raw material gases containing nitrogen atoms used in the first and second surface layers 4 and 5 may be the same or different. However, the nitrogen concentration in the second surface layer 5 must be higher than the nitrogen atom concentration in the first surface layer 4. In addition to nitrogen atoms, other elements can also be added to these first and second surfaces (FIGS. 4 and 5), which are mainly composed of amorphous silicon, for various purposes.

The nitrogen atom concentration in the first surface diagram 4 is preferably in the range of 0.1-LO as an atomic ratio to silicon atoms. Moreover, the film thickness is preferably in the range of 0.01-5 μm.

The nitrogen atom concentration in the second surface layer 5 is preferably in the range of 0.5-1.3 as an atomic ratio to silicon atoms. Moreover, the film thickness is preferably in the range of 0.01-5 μm.

The electrophotographic photoreceptor of the present invention can be used in any electrophotographic process, but is particularly advantageous in an electrophotographic process in which at least the surface of the photoreceptor is heated to 35 to 50°C. can be used. This is because when used with the photoreceptor surface heated to the above range, it provides a stable and high-quality initial image under any usage environment, and the image quality does not deteriorate even after repeated use. That's because there isn't.

Such an electrophotographic process will be explained with reference to FIG.

FIG. 4 shows a schematic groove configuration of an electrophotographic apparatus using the electrophotographic photoreceptor of the present invention, where 6 is the electrophotographic photoreceptor of the present invention, and 7 is the photoreceptor placed in a dark place. 8, a latent image forming means for exposing a photoreceptor to a light image corresponding to the original image to form a latent image; 9, making the latent image visible with toner powder; 10 is a transfer means for transferring the developed image onto a transfer member; 1
1 is a fixing means for fixing the transferred image, 12 is a cleaning means, 13 is a transfer paper, 14 is a photoreceptor heating means,
A quartz lamp is installed in the rotating shaft.

The means for heating the photoreceptor can be provided at any position. In FIG. 4, the photoreceptor heating means 14 is provided inside the rotation shaft for rotating the photoreceptor, or is placed on the circumferential surface of the photoreceptor like the developing means, charging means, transfer means, etc. It may be provided at an appropriate position. Further, it is possible to provide this not only on the photoreceptor layer side but also on the support side. When provided on the support side, its position can be set arbitrarily, but
For example, a planar heater that heats the photoreceptor evenly close to the photoreceptor support side is preferable.

As a means for heating the photoreceptor, heat lamps such as quartz lamps (quartz lamps) in which nichrome wires are arranged in quartz glass, heat-resistant flexible materials such as silicone rubber [sheet heaters in which nichrome wires are arranged in raw rubber, etc.] are used. However, other methods such as a hot air blower type heater, a heater that uses radiant heat such as infrared rays, and a heater that uses heat from the fixing section are also applicable. Any means for supplying electricity to the photoreceptor heating means can be used, but in particular when the heating means is provided inside the photoreceptor support, the photoreceptor rotates, so a slip ring may be used. It is preferable to use a device that conducts electricity through the device.

EXAMPLES Hereinafter, the present invention will be specifically explained using examples and comparative examples.

Example 1 Using a capacitively coupled plasma CVD device capable of forming an amorphous silicon film on a cylindrical support, silane (SIH4) was
A charge injection blocking layer having a thickness of about 0.5 μm was produced on a cylindrical aluminum support by glow discharge decomposition of a mixture of gas, hydrogen (H2) gas, and diphorane (B2H6) scum. The manufacturing conditions at this time were as follows.

100% silane gas flow 1: 100cm3/mi 11001) l) Hydrogen diluted diborane gas flow 'J=:
2006m3/mi Sleep reactor internal pressure: 0.5 tons orr
1 Discharge type crab 100W.

Discharge time: 30 m/hole, Discharge frequency, 13.56 min Z1 Support temperature: 250°C0 (Incidentally, in all the examples and comparative examples described below, the discharge frequency and support temperature under the manufacturing conditions of each layer are as follows: (The value was fixed at the above value.) After forming the charge injection blocking layer, the inside of the reactor was sufficiently evacuated, and then a mixture of silane gas, hydrogen gas, and diborane gas was introduced and decomposed by glow discharge to form a charge injection blocking layer. A charge transport layer with a thickness of about 20 μm was formed on top. The manufacturing conditions at this time were as follows.

100% silane gas flow fij: 2000m3/m
in, ioo% hydrogen gas flow 1jA: 1806m3
/min.

1100pp hydrogen diluted diporan gas flow rate: 20cm3
/min, reactor internal pressure: 1.5 Torr.

Discharge cylinder crab 3004, discharge time: 240 m1n0 After the charge transport layer is formed, the inside of the reactor is sufficiently evacuated, and then silane gas, hydrogen gas, and germane (G e H4
) A charge generation layer having a thickness of about 2 μm was produced on the charge transport layer by introducing a gas mixture and performing glow discharge decomposition. The manufacturing conditions at this time were as follows.

100% silane gas flow 74: 120cm/min
.

ioo% hydrogen gas flow m: 1500m3/mi 1
00% Germanic gas flow m: 30 cm3/min
, reactor internal pressure: 1.3 Torr, discharge cylinder crab 200W, discharge time H3Om1n.

After the charge generation layer is formed, the inside of the reactor is sufficiently evacuated, and then a mixture of silane gas, hydrogen scum, and ammonia gas is introduced and decomposed by glow discharge to form a film with a thickness of approximately 0.3 μm on the charge generation layer. A first surface layer was produced having a . The manufacturing conditions at this time were as follows.

100% silane gas flow%: 30 cm3/mi 100% hydrogen gas flow: 2000 m3/mi
oo% ammonia gas flow m: 30 cm3/mi
n, Reactor internal pressure: 0.5 Torr 1 Discharge cylinder crab 50-1 Discharge time: 60 m1n0 When the composition of this surface layer was analyzed, the atomic ratio of nitrogen atoms to silicon atoms was approximately 0.6.

After the formation of the first surface layer, the inside of the reactor is sufficiently evacuated, and then a mixture of silane gas, hydrogen gas, and ammonia gas is introduced for glow discharge decomposition, so that about 0% A second surface layer was produced with a thickness of .1 μm. The manufacturing conditions at this time were as follows.

100% silane gas flow ti: 17 cm3/mi
n, 100% hydrogen scum flow rate: 2000m3/min
, 100% ammonia gas flow rate: 43 cm3/m
Sleep reactor internal pressure: 0.5 Torr.

Discharge cylinder crab 50mm, discharge time: 20m1n0 When the composition of this surface layer was analyzed, the atomic ratio of nitrogen atoms to silicon atoms was about 0.8.

An electrophotographic photoreceptor having a charge injection blocking layer, a charge transport layer, a charge generation layer, a first surface layer, and a second surface layer on an aluminum support obtained as described above is printed using a semiconductor laser printer to improve image quality. We conducted an evaluation. The printer settings were three types: 30° C./85% RH, 20° C. 150% RH1, and 10° C./15% RH. (Hereinafter, these three types of environments will be collectively referred to as three environments.) Furthermore, the drum heating device in the printer was operated so that the temperature of the drum surface was approximately 45°C.

In this case, clear images were shown in the three environments at the initial stage. In addition, we conducted a printing test of approximately 20,000 sheets in an environment of 20°C and 150% RH for the initial image quality evaluation, and then evaluated the image quality by changing the printer installation environment. I was able to obtain clear images that were virtually unchanged from the initial images.

In general, the printed matter obtained in this evaluation was at the initial stage and at about 20
．． Even after copying 1,000 sheets, high image density with no fog was exhibited. Furthermore, no image quality defects due to scratches on the surface of the photoreceptor were observed.

Furthermore, when the electrophotographic photoreceptor produced in this example was evaluated in a copying machine, it was found to have excellent resolution and gradation reproducibility even in any environment, and exhibited high density without fogging.

Example 2 A charge injection blocker was produced on an aluminum support using the same equipment and the same conditions and method as in Example 1.

After the charge injection blocking layer is formed, the inside of the reactor is sufficiently evacuated.
Next, a mixture of silane gas, hydrogen gas, and germane gas was introduced and decomposed by glow discharge to form a charge generation layer having a thickness of approximately 2 μm on the charge injection blocking layer. The manufacturing conditions at this time were the same as those for forming the charge generation layer in Example 1.

After the charge generation layer is formed, the inside of the reactor is sufficiently evacuated, and then a mixture of silane gas, hydrogen gas, and diborane gas is introduced and glow discharge decomposition is performed to form a charge having a film thickness of about 20 μm on the charge generation layer. A transport layer was generated. The manufacturing conditions at this time were the same as those for forming the charge transport layer in Example 1.

Following the formation of the charge transport layer, a first surface layer and a second surface layer were sequentially formed on the charge transport layer under the same conditions and method as in Example 1.

An electrophotographic photoreceptor having a charge injection blocking layer, a charge generation layer, a charge transport layer, a first surface layer, and a second surface layer on an aluminum support obtained as described above is printed using a semiconductor laser printer to improve image quality. We conducted an evaluation. At this time, the drum heating device in the printer was operated so that the temperature of the drum surface was 45°C.

In this case, clear images were formed in the three environments at the initial stage. In addition, after initial image quality evaluation, 20℃ 150%RH
We conducted a printing test of approximately 20,000 sheets under the following environment, and then evaluated the image quality by changing the printer's installation environment. In all three environments, we were able to obtain clear images that were virtually unchanged from the initial one. It was done.

Roughly speaking, the stamp side objects obtained in this evaluation are initial and about 20
,000 copies, it showed high image density with no fog. Furthermore, no image quality defects due to scratches on the surface of the photoreceptor were observed.

In addition, when the electrophotographic photoreceptor produced in this example was evaluated in a copying machine, it showed excellent resolution and gradation reproducibility and high image density without fogging in any environment.

Comparative Example 1 A charge injection blocking layer, a charge transport layer, and a charge generation layer were sequentially formed on an aluminum support using the same apparatus and the same conditions and method as in Example 1.

However, the first surface layer and the second surface layer were not formed.

When we evaluated the image quality of the photoreceptor for electrophotography using a printer that uses a semiconductor laser as a light source, we found that initially it gave a clear image, but after about 1,000 copy tests, we noticed that the image was blurry. It was done.

Comparative Example 2 A charge injection blocking layer, a charge generation layer, and a charge transport layer were sequentially formed on an aluminum support using the same apparatus, the same conditions, and the same method as in Example 2.

However, the first surface layer and the second surface layer were not formed.

When the image quality of the obtained electrophotographic photoreceptor was evaluated using a printer using a semiconductor laser as a light source, it gave a clear image at the initial stage, but after about 1,000 copy tests, the image blur became I2. It was noticed.

Comparative Example 3 A charge injection blocking layer, a charge transport layer, and a charge generation layer were sequentially formed on an aluminum support using the same apparatus, the same conditions, and the same method as in Example 1.

After the charge generation layer is formed, the inside of the reactor is sufficiently evacuated, and then a mixture of silane gas, hydrogen gas, and ammonia gas is introduced, and glow discharge decomposition is performed to form a film of about 0.3μ on the charge generation diagram. A surface layer with a thickness was produced. The manufacturing conditions at this time were as follows.

ioo% silane gas flow: 170 (B3/q+in
, 100% hydrogen gas flow 1a: 200cR+3/m
in, 100% ammonia gas flow rate: 43 cm
/min.

Reactor internal pressure: 0.5 Torr.

Electric discharge crab 50 buttocks, Discharge time: 60mln.

When the composition of this surface layer was analyzed, the atomic ratio of nitrogen atoms to silicon atoms was approximately 0.8.

When the image quality of an electrophotographic photoreceptor having a charge injection blocking layer, a charge transport layer, a charge generation layer, and a surface layer formed on an aluminum support as described above was evaluated using a semiconductor laser printer, the initial Time (number 1
0 cycles), severe image blurring was observed in each of the three environments.

Comparative Example 4 A charge injection blocking layer, a charge transport layer, a charge generation layer, and a first surface layer were sequentially formed on an aluminum support using the same apparatus and the same conditions and method as in Example 1. However, the second surface layer was not formed.

When the image quality of the obtained electrophotographic photoreceptor was evaluated using a semiconductor laser printer, it showed clear images in the three environments at the initial stage. On the other hand, after initial image quality evaluation,
A copying test of approximately 20,000 sheets was conducted in an environment of 150% RH, and then the image quality was evaluated in different environments.As a result, resolution, image density, fog, etc. Items were wet, substantially different from the initial condition, but at 30℃/85%RH and 10℃/1
In an environment of 5% RH, image blurring was observed.

Comparative Example 5 Image evaluation of the electrophotographic photoreceptor produced in Comparative Example 4 was performed in the same manner. However, the drum heating device in the printer was turned on to bring the drum surface to about 45°C.

In this case, clear images were shown in the three environments at the initial stage. On the other hand, for initial image quality evaluation, we conducted a copying test of approximately 20,000 sheets in an environment of 20°C/150% RH, and then changed the printer installation environment and evaluated the image quality. %RH environment, clear images were obtained, but at 20°C/150%RH and 10°C/15%R
Under the H environment, image blurring occurred.

Effects of the Invention Since the electrophotographic photoreceptor of the present invention has the above-described structure, it provides a high-quality initial image and has excellent stability over time and printing durability. In addition, this electrophotographic photoreceptor is
It has high photosensitivity not only in the visible light region but also in the near-infrared region emitted by semiconductor lasers (radius wavelength), has high dark resistance and excellent centering ability, and also has characteristics that are not dependent on the usage environment. It has the excellent property of being small.

Therefore, the obtained copied image has excellent resolution and gradation reproducibility, and exhibits high image density without fog both at the initial stage and after a long period of repeated operations.

Furthermore, the electrophotographic photoreceptor of the present invention can be particularly advantageously used in an electrophotographic process in which at least the surface of the photoreceptor is heated to 35 to 50°C. In other words, when used with the photoreceptor surface heated to the above range, it provides a stable and high-quality initial image under any usage environment, and does not cause deterioration in image quality even after repeated operations. .

[Brief explanation of drawings]

1 to 3 are schematic diagrams showing the structure of the electrophotographic photoreceptor of the present invention, and FIG. 4 is a schematic diagram showing the structure of an electrophotographic device using the electrophotographic photoreceptor of the present invention. This is an explanatory diagram. DESCRIPTION OF SYMBOLS 1... Support, 2... Charge injection blocking layer, 3... Photoconductive layer, 31... Charge transport layer, 32... Charge generation layer, 4... First surface layer, 5... second surface layer, 6.
. . . Photoreceptor for electrophotography, 7 . . . -Charging means, 8 . . .・Cleaning means,
13... Transfer paper, 14... Photoreceptor heating means. Figure 7, Figure 2, Figure 3, Atsushi, Figure 4

Claims (5)

[Claims] (1) Constructed by sequentially laminating a photoconductive layer, a first surface layer, and a second surface layer on a support, and the photoconductive layer is doped with germanium atoms in at least a part of its layer area. The first surface layer and the second surface layer each mainly contain amorphous silicon doped with nitrogen atoms, and the second surface layer contains nitrogen atoms. An electrophotographic photoreceptor characterized in that the concentration of nitrogen atoms is higher than the concentration of nitrogen atoms in the first surface layer. (2) The photoconductive layer is composed of two layers: a charge generation layer and a charge transport layer, the charge generation layer is mainly made of amorphous silicon doped with germanium atoms, and the charge transport layer is a third layer.
The photoreceptor for electrophotography according to claim 1, characterized in that the electrophotographic photoreceptor is mainly composed of amorphous silicon to which a group element is added. (3) The electrophotographic photoreceptor according to claim 1 or 2, further comprising a charge injection blocking layer between the support and the photoconductive layer. (4) The electrophotographic photoreceptor according to claim 3, wherein the charge injection blocking layer is made of amorphous silicon doped with a group III element or a group V element. (5) Claims 1, 2, 3, or 4 for use in an electrophotographic process in which at least the surface of the photoreceptor is heated to 35 to 50°C.
The electrophotographic photoreceptor described in .