JP2001318504A - Electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic device including plural photoreceptors which are uniform in the life of the plural photoreceptors, are high in reliability and low in running costs. SOLUTION: This electrophotographic device includes the plural photoreceptors which are formed by laminating surface protective layers consisting preferably of any of a-SiC:H, a-SiN:H, a-C:H and a-CN;H on photosensitive layers containing at least amorphous Si and in which the film thickness or hardness of at least one surface protective layer of the photoreceptors is different from that of the surface protective layers of the other photoreceptors.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor having a plurality of photoreceptors, of which at least one of the surface protective layers has a different thickness or hardness from the surface protective layers of the other photoreceptors. And an electrophotographic apparatus.

[0002]

2. Description of the Related Art Conventionally, a plurality of image forming units are provided, and in each image forming unit, a visible image (toner image) having a different color is formed, and these toner images are sequentially transferred onto the same recording material in a superimposed manner. Various types of image forming apparatuses, so-called color image forming apparatuses, have been proposed. Among them, an electrophotographic color image forming apparatus is frequently used. In such an electrophotographic color image forming apparatus, a plurality of image forming units, generally four image forming units, are arranged side by side, and a dedicated photosensitive drum is used as an image carrier of these image forming units. Yellow, magenta, cyan,
A black visible image, that is, a toner image is formed separately, and toner images of each color are sequentially transferred onto a recording material carried and conveyed by a recording material carrying means composed of a dielectric belt, for example. A required full-color image or multi-color image is obtained by heating and fixing the multiple toner images on the recording material collectively by a fixing device. Since this method enables a color image to be output at a high speed, many color image apparatuses using this method have been put on the market.

An example of such an electrophotographic color image forming apparatus will be briefly described with reference to FIG. This color image forming apparatus is capable of forming, for example, visible images (toner images) of respective colors of yellow, magenta, cyan, and black in the apparatus main body, and includes first to fourth four image forming units Pa, Pb, and Pc. And Pd are linearly arranged, and each of the image forming units Pa to Pd includes dedicated photosensitive drums 1a, 1b, 1c and 1d as image carriers, respectively. Each of the photoreceptor drums 1a to 1d is driven to rotate in the direction of the arrow shown in the figure, and the periphery thereof is a dedicated image forming process means, for example, a primary charger 2a,
2b, 2c, 2d, image exposure devices 3a, 3b, 3c, 3
d, developing units 4a, 4b, 4c, 4d, and cleaner 5
a, 5b, 5c, 5d, etc. are provided.

A recording material supporting means, in this example, an endlessly moving recording material carrying belt 8 is provided between a plurality of rollers in a known manner below the photosensitive drums 1a to 1d of the image forming portions Pa to Pd. The transfer charging means 6a, 6b, 6c, and 6d are respectively disposed inside. Further, in the drawing of the recording material carrying belt 8, a paper feed unit is disposed on the right side, and the fixing unit 7 is disposed on the opposite side, that is, on the left side in FIG. Further, a pair of registration rollers 13 for feeding the recording material P at a time is arranged between the paper supply unit and the recording material carrying belt 8. 13, is fed onto and held on the recording material carrying belt 8, and moves along the belt 8 in the direction indicated by an arrow in FIG.
It is sequentially conveyed to the transfer area of Pd.

In the above-described configuration, the recording material P sent from the paper feeding unit is temporarily stopped when its tip is slightly sandwiched by the registration rollers 13, and the image forming process and the timing of the first image forming unit Pa are stopped. The sheets are fed together and fed onto the recording material carrying belt 8. The first image forming unit Pa scans the photosensitive drum 1a, which is uniformly charged by the primary charger 2a, with image information of the yellow component color in the original image by using a laser beam or the like to scan the electrostatic of the yellow component color. A latent image is formed. This electrostatic latent image becomes a yellow visible image by the yellow toner attached thereto in the developing device 3a.

On the other hand, the recording material P is conveyed while being carried on a recording material carrying belt 8, and in the transfer area below the photosensitive drum 1a of the first image forming portion Pa, the photosensitive member is operated by the transfer charging means 6a. The yellow visible image formed on the drum 1a, that is, the toner image is transferred onto the recording material P. While the yellow toner image is being transferred onto the recording material P in this way, an electrostatic latent image of a magenta component color is formed in the second image forming portion Pb, and this electrostatic latent image is formed by the developing device 3b. When the recording material P is conveyed to a transfer area below the photosensitive drum 1b of the second image forming portion Pb, the magenta toner image moves to the transfer area, and the transfer material P By the action, it is transferred in a state of being superimposed on the yellow toner image on the recording material P.

Hereinafter, the third and fourth image forming units Pc and Pd will be described.
Also, similarly to the first and second image forming units Pa and Pb, cyan and black toner images are sequentially formed,
These toner images are sequentially multiplex-transferred onto the recording material P conveyed by the recording material carrying belt 8.

When the image forming process is completed, the recording material P is separated from the recording material carrying belt 8 and sent to the fixing device 7, where it is collectively fixed to obtain a desired full-color image. Further, the photosensitive drums 1a to 1d of the image forming units Pa to Pd after the transfer have been completed.
In steps a to 5d, the residual toner is removed to prepare for the subsequent latent image formation.

The image forming apparatus having the above-described structure is advantageous in speeding up since it has an image forming unit for each color, but is expensive because it has four photosensitive drums which are consumables, and is expensive. Even when an image is formed (usually black), the four photosensitive drums rotate while being in contact with the recording material carrying belt 8 in the same manner as the drum for forming an image. And the life is shortened.

In recent years, with the progress of digitization, the above-mentioned color printer, which is frequently used as an output device of a computer, is required to have a high operation rate and high reliability, and reducing the frequency of replacement due to drum wear is a major issue. In addition, from the viewpoint of ecology, eliminating waste, that is, reducing consumables and extending the life of consumables, specifically,
It is our absolute task to increase the durability and the reliability of the drum, which has more than one million drums. From another perspective, the reduction of carbon dioxide, that is, the reduction of power consumption and the protection of forests, are also issues clearly imposed as global standards. Specifically, reduction of power consumption during standby of a heater or the like,
The use of recycled paper, non-wood pulp paper, and the like is becoming active. Under these circumstances, there is a demand for not only extending the life but also reducing and eliminating drum heaters and promoting the wear of the drum by the filler used for recycled paper.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. Hei 7-13399, it is set or automatically recognized whether the image to be formed is a black-and-white image or a color image for the purpose of shortening the copying time when forming a single-color image. Various image forming apparatuses equipped with functions have been proposed. As disclosed in Japanese Patent Application Laid-Open No. Hei 5-341618, photosensitive drums 1a to 1d not used for image formation when forming a monochromatic image and a recording material support A proposal has been made to make the belt 8 non-contact.

Conventionally, an OPC drum has been used as a photosensitive drum in such an electrophotographic color image forming apparatus. The OPC drum has advantages that it is rich in mass productivity, relatively inexpensive, and does not necessarily require a drum heater.

[0013]

However, the OPC
Since the service life of the drum is shorter than the service life of the main body, it is necessary to periodically replace the drum cartridge by a service person. Further, as described above, the life of the photoconductor drum differs depending on the frequency of use, so that the replacement becomes more complicated, the stop time becomes longer, and as a result, the operation rate per hour is reduced. .

An object of the present invention is to provide an electrophotographic apparatus having a plurality of photoconductors, in which the life of the plurality of photoconductors is uniform, high quality images can be provided, and running costs and resource consumption can be reduced. To provide.

Another object of the present invention is to provide a photoreceptor group having a uniform photoreceptor life for use in an electrophotographic apparatus having a plurality of photoreceptors.

[0016]

The above objects of the present invention are attained by the inventions described below.

(1) An electrophotographic apparatus having a plurality of photoconductors, wherein each photoconductor includes at least amorphous Si.
A surface protective layer made of an amorphous material is laminated on a photosensitive layer containing at least one of the photosensitive members so that the life of the plurality of photosensitive members is uniform. An electrophotographic apparatus, wherein the thickness of the protective layer is different from that of the protective layer.

(2) An electrophotographic apparatus including a plurality of photoconductors, wherein each photoconductor includes at least amorphous Si.
A surface protective layer made of an amorphous material is laminated on a photosensitive layer containing, and the hardness of at least one surface protective layer of at least one photosensitive member is set so that the life of the plurality of photosensitive members is equal. An electrophotographic apparatus, wherein the hardness of the layer is different from that of the layer.

(3) A photoreceptor group used in an electrophotographic apparatus having a plurality of image forming units, wherein each photoreceptor has a surface protective layer made of an amorphous material laminated on a photosensitive layer containing at least amorphous Si. The thickness of the surface protective layer of at least one of the photoconductors is different from the thickness of the surface protective layer of the other photoconductor so that the life of the photoconductor group is uniform. Photoconductor group.

(4) A photoreceptor group used in an electrophotographic apparatus having a plurality of image forming units, wherein each photoreceptor has a surface protective layer made of an amorphous material laminated on a photosensitive layer containing at least amorphous Si. The photoreceptor group, wherein the hardness of the surface protective layer of at least one of the photoreceptors is different from the hardness of the other surface protective layers so that the life of the photoreceptor group is uniform.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, at least one
By making the thickness or hardness of the surface protective layer of the photoreceptor different from the thickness or hardness of the surface protective layer of other photoreceptors in accordance with the frequency of use of each photoreceptor, It is possible to provide a high quality image without the need to replace the drum cartridge even when the body (drum) is used for a long time without the life of the body (drum) coming first. That is, the thickness or hardness of the photoconductor is made larger than that of other photoconductors in accordance with the frequency of use.

In the present invention, the amorphous material used as the surface protective layer includes a-SiC: H, a-
SiN: H, aC: H and / or a-CN: H are preferred. By using such an amorphous material,
It is thought that it became possible to control the deposits on the surface protective layer, and it was also possible to simultaneously prevent the high humidity flow.

In the present invention, the thickness of the surface protective layer made of the above-mentioned amorphous material is made larger in at least one photosensitive member than in the other photosensitive members, that is, at least one surface of the photosensitive member. The initial thickness of the protective layer is Ta, and the thickness of the surface protective layer of the other photoconductor is Tb.
Where preferably, 1.1 ≦ Ta / Tb ≦ 2.0 and 650 nm ≦ [Ta or Tb] ≦ 13
By setting the thickness to 00 nm, the lifetimes of a plurality of photoconductors can be made uniform while preventing an increase in residual potential and a decrease in sensitivity.

Further, the present inventors have found that the wear rate of the surface protective layer can be controlled by controlling the hardness of the surface protective layer as shown in FIG.

In FIG. 2, the a-SiC: H protective layer and the aC: H surface protective layer have a gas mixture ratio, a gas flow rate, a film forming furnace internal pressure, a film forming discharge power, and a substrate temperature as described later. Under control, photoconductors having a plurality of hardnesses were produced. This was obtained by modifying the cleaner part of NP6750 manufactured by Canon Inc. into an elastic cleaning roller, performing a durability test, and plotting the wear rate of the surface layer on a graph. As is apparent from the results, it is considered that the wear life can be controlled using the hardness as a scale. In the present invention, when the hardness of the surface protective layer of one photosensitive member is defined as Ha and the hardness of the surface protective layer of another photosensitive member is defined as Hb, preferably, 1.1 ≦ Ha /
Hb ≦ 3.0 and 3000 N / mm ² ≦
By setting [Ha or Hb] ≦ 13000 N / mm ² , the life of a plurality of photoconductors can be uniform.

The structure of the photoreceptor for an electrophotographic apparatus according to the present invention will be described below with reference to FIG. FIG. 1 is a schematic sectional view of a typical amorphous silicon photosensitive member used in the present invention. In FIG. 1, a photoconductor is formed by sequentially laminating a photoconductive layer 302 made of non-single-crystal silicon containing at least hydrogen and a surface protective layer 304 on a conductive substrate 301. In addition, a charge injection blocking layer 305 may be added to improve the ability to block charges from the substrate.

The deposition of the light receiving member by the plasma CVD method can be performed by a known method, but the higher the high-frequency power (power), the higher the possible power is aC: H, a-CN: H
In the case of amorphous carbon-based film formation such as described above, hydrocarbons are particularly preferable because the decomposition of hydrocarbons proceeds sufficiently. Specifically, it is preferably 5 W / cm ³ or more with respect to the hydrocarbon raw material gas. However, if it is too high, an abnormal discharge occurs and the characteristics of the electrophotographic photoreceptor are deteriorated. It needs to be suppressed.

With respect to the pressure in the discharge space, when a film is formed from a raw material gas which is hardly decomposed such as a hydrocarbon, a polymer is liable to be generated if there is a collision between decomposed main bodies in a gas phase. High vacuum is desirable. 13.3P when using normal RF (typically 13.56 MHz) power
a to 1330 Pa, VHF band (typically 50 to 450
MHz) when using 13.3 mPa to 13.3 P
a is maintained.

The photoreceptor manufactured as described above may be further used, if necessary, in Japanese Patent No. 2047474 (Japanese Patent Publication No.
It is particularly preferable that the abnormally-grown protrusions are polished by a photoreceptor surface treatment method as described in 7-07702) so that Rmax is 5 μm or less.

[0030]

EXAMPLES The present invention and its effects will be empirically described below by showing experimental examples, examples and comparative examples, but it should not be understood that the present invention is limited by these examples. The photoreceptors used in these examples were those polished so that the abnormal growth projections Rmax were 5 μm or less as described above.

Experimental Example 1 After a charge injection blocking layer and a photoconductive layer were laminated on a cylindrical conductive substrate under the conditions shown in Table 1 using a plasma CVD apparatus,
Under the conditions of Table 2, the thickness of the surface protective layer was set to 620 to 1930 nm.
And electrophotographic photosensitive members were manufactured.

Next, the photosensitive member is transferred to a Canon copier CL.
Modified C1000 (135mm / s process speed)
ec) and a continuous paper passing durability test of 3 million sheets (43
(100,000 rotations) to measure the amount of wear and evaluate the high humidity flow. Originals are Bk (black), Y at 6% original density.
(Yellow), M (magenta), and C (cyan) have a color standard chart of Bk: 25% Y: 25% M: 25% C: 25% and a character (black) chart of 6% original density The test was performed using the same number of combinations. In this experimental machine, as a means for rubbing the surface protective layer of the photoreceptor,
A cleaning blade and an elastic cleaning roller were installed. Further, this experimental machine is equipped with a function of automatically recognizing whether a formed image is a black-and-white image or a color image, so that the photosensitive drums other than Bk are not worn when printing the character chart.

The film thickness of the surface protective layer is measured at a plurality of locations on the photoreceptor with a spectrophotometer (MCPD2000 manufactured by Otsuka Electronics Co., Ltd.), and based on the obtained spectral reflection waveform and the refractive index of the film, the thickness of each location is determined. After calculating the film thickness, the average was obtained.

The amount of wear of the surface protective layer is obtained by measuring the thickness of the surface protective layer before and after the durability test in the same manner, and converting the value to the amount of wear per 10,000 revolutions.

The residual potential was measured using a surface potentiometer (344 manufactured by Trek) so that the surface potential at the developing device could be measured by modifying a Canon CLC1000 copying machine as a measuring device.
Etc.) were prepared. The temperature of the photoconductor and the main static elimination light are set in a predetermined state, the photoconductor is set and rotated, and the surface potential at the time when the image exposure amount is maximized is measured as the residual potential.

The potential shift is determined as a potential shift by measuring the potential change for 2 minutes with the image exposure turned off following the residual potential.

FIG. 3 is a graph showing the results of this experiment.
Regarding the remaining film thickness of the surface protective layer of the Bk drum after the durability test of 3 million sheets, the result is obtained when the initial film thickness is changed. It can be seen that the remaining film thickness monotonically increases as the initial film thickness increases. . Further, the film thickness of the surface layer of the drum where the image quality began to deteriorate was measured and found to be 60 nm. However, it is considered that the surface layer partially disappeared, and it became impossible to withstand practical use. According to the study of the present inventors, the surface layer thickness at which the image quality began to deteriorate was 60 nm, but a variation of about 30 to 100 nm was predicted, and it was judged comprehensively that if the initial film thickness was smaller than 650 nm. It was determined that the service life was insufficient and printing of 3 million sheets could not be guaranteed.

FIG. 4 is a graph showing the results of this experiment.
The residual potential is a result when the initial film thickness is changed. It can be seen that the residual potential monotonically increases as the initial film thickness increases, and that the residual potential rapidly increases when the initial film thickness exceeds 1300 nm.

FIG. 5 is a graph showing the results of this experiment.
The potential shift is a result when the initial film thickness is changed. As the initial film thickness increases, the potential shift increases monotonically, and when the initial film thickness becomes larger than 1300 nm, the residual potential rapidly increases. I understand.

The same experiment was performed on the a-SiN: H surface layer, aC: H surface layer and a-CN: H surface layer in Tables 3 to 5, but almost the same tendency was measured. The effect can be expected.

Experimental Example 2 In the same manner as in Experimental Example 1, a charge injection blocking layer and a photoconductive layer were laminated on a cylindrical conductive substrate under the conditions shown in Table 1 using a plasma CVD apparatus. Hardness of protective layer is 2
The electrophotographic photosensitive member was manufactured by depositing the film while changing the thickness from 800 to 14500 N / mm ² . The film thickness is about 500nm
And

Next, in the same manner as in Experimental Example 1, the photosensitive member was mounted on a remodeled machine (a process speed of 135 mm / sec) of a copying machine CLC1000 manufactured by Canon, and a continuous paper passing durability test was performed on 2 million sheets (2.8 million rotations). The measurement of the amount of wear and the evaluation of the high humidity flow were performed. The hardness of the surface protective layer of the photoconductor drum is measured using a dynamic ultra-micro hardness tester (Shimadzu DUH)
-201S), and the dynamic hardness was measured at multiple points and averaged.

FIG. 6 is a graph showing the results of this experiment.
Regarding the remaining film thickness of the surface protective layer in the Bk drum after the durability test of 2 million sheets, it is a result when the hardness of the surface protective layer is changed. It can be seen that the film thickness monotonically increases as the hardness increases. . Further, the film thickness of the surface layer of the drum where the image quality began to deteriorate was measured and found to be 60 nm.
However, it is considered that the surface layer partially disappeared, and it became impossible to withstand practical use. According to the study by the present inventors, the surface layer thickness at which the image quality started to deteriorate was Rz60n.
m, but 30 to 10 depending on the film forming conditions of the photosensitive layer.
Variations of about 0nm are expected and comprehensively judged,
When the hardness was less than 3000 N / mm ² , the life was short, and it was determined that printing of 2 million sheets could not be guaranteed.

FIG. 7 is a graph showing the results of this experiment.
This is the result when the hardness of the surface protective layer is changed for the high-humidity image flow. Regarding the evaluation of high humidity flow,
The image level was evaluated after being left overnight in a high-temperature, high-humidity environment at 2 ° C. and a relative humidity of 80%. A: No image deletion occurred, B: Slight image deletion occurred, but no practical problem occurred. C: There was a practical problem.

It can be seen that the level of image deletion deteriorates as the hardness increases. Furthermore, hardness is 13000N
It can be seen that the level of the image flow sharply deteriorates when the ratio exceeds / mm ² .

Here, a-SiC: H is used as the surface protective layer.
Although the surface layer was taken as an example, a similar experiment was conducted using a-SiN: H
The same procedure was performed for the surface layer, aC: H surface layer and a-CN: H surface layer, but almost the same tendency was measured, and similar effects can be expected.

[0047]

TABLE 1 Light-receiving member manufacturing conditions blocking layer _{···· SiH 4 300ml / min H 2} 500ml / min NO 8ml / min B 2 H 6 2000ppm power 100W (13.56 MHz) pressure 53.2 Pa (0.4 torr ) Film thickness 1 μm Photoconductive layer: SiH ₄ 500 ml / min H ₂ 500 ml / min Power 400 W (13.56 MHz) Internal pressure 66.5 Pa (0.5 torr) Film thickness 25 μm

[0048]

Table 2 Manufacturing conditions for surface protective layer of Experimental Example 1 SiH ₄ / CH ₄ 20 ml / min / 300 ml / min Power 150 W (13.56 MHz) Temperature 250 ° C. Internal pressure 53.2 Pa (0.4 torr)

[0049]

Table 3 Other manufacturing conditions of surface protective layer of Experimental Example 1 SiH ₄ / N ₂ 1 ml / minm / 100 ml / min Power 500 W (13.56 MHz) Temperature 250 ° C. Internal pressure 53.2 Pa (0.4 torr)

[0050]

Table 4 Other manufacturing conditions of the surface protective layer of Experimental Example 1 CH ₄ 200 ml / min Power 1000 W (105 MHz) Temperature 200 ° C. Internal pressure 7 Pa (0.05 trr)

[0051]

Table 5 Other manufacturing conditions of the surface protective layer of Experimental Example 1 CH ₄ / N ₂ 100 ml / min / 200 ml / min Power 150 W (13.56 MHz) Temperature 220 ° C. Internal pressure 53.2 Pa (0.4 torr)

[0052]

Table 6 Production conditions for surface protective layer of Experimental Example 2 SiH ₄ / CH ₄ (A) 10 ml / min / 500 ml / min (B) 10 ml / min / 600 ml / min (C) 10 ml / min / 700 ml / min ( D) 30 ml / min / 300 ml / min Power 150 W (13.56 MHz) Temperature 250 ° C. Internal pressure 53.2 Pa (0.4 torr) In the following examples, the present invention will be further described. As long as the above conditions are satisfied,
It is needless to say that a uniform layer is not essential, and a multilayer / graded layer may be preferable.

Example 1 In the same manner as in Experimental Example 1, Table 1 was obtained by using a plasma CVD apparatus.
After the charge injection blocking layer and the photoconductive layer were laminated on the cylindrical conductive substrate under the conditions described in the above, a surface protective layer was deposited under the conditions shown in Table 2 to produce an electrophotographic photoreceptor.

Next, the photosensitive member is transferred to a Canon copier CL.
Modified C1000 (135mm / s process speed)
ec), and a continuous paper passing durability test of 3 million sheets (4.3 million rotations) was performed to measure the amount of wear and evaluate the image. Originals are Bk (black), Y at 6% original density.
(Yellow), M (magenta), and C (cyan) have a color standard chart of Bk: 25% Y: 25% M: 25% C: 25% and a character (black) chart of 6% original density The same number was combined in each case.

The film thickness for protecting the surface of the photoconductor for Bk printing is T
a, when the thickness of the surface protective layer of the other photoconductor is Tb,
The thickness ratio Ta / Tb was set to 1.4.

For image evaluation, high humidity flow and density stability during continuous printing were evaluated.

Regarding the evaluation of the high humidity flow, after printing, 32
After being left overnight in a high-temperature, high-humidity environment at 80 ° C. and a relative humidity of 80%, image evaluation was performed.

With respect to the evaluation of image stability, solid-color solid copy was performed by continuous printing, and the image was measured for reflectivity using a reflectometer to check the change in image density caused by potential shift.

Table 7 shows the results obtained in the above evaluation.

In Table 7, the symbol 〇: excellent, △:
No problem in practical use, ×: Means a problem in practical use.

As is evident from the table, the results of the system according to the present example were excellent overall.

Comparative Example 1 The life, the image flow, and the density stability when the film thickness ratio Ta / Tb was 1.0 were evaluated in the same manner as in Example 1. Table 7 shows the results. As is clear from this table, the result was that the life was poor and there was a practical problem overall.

Comparative Example 2 The life, image deletion, and density stability when the film thickness ratio Ta / Tb was 2.2 were evaluated in the same manner as in Example 1. Table 7 shows the results. As is clear from this table, although the result of the concentration stability was slightly poor, it was at a level where there was no problem in practical use, and the result was that there was no problem in practice overall.

Comparative Example 3 In the same manner as in Example 1, the life, image flow, and density stability when the film thickness ratio Ta / Tb was 3.1 were evaluated. Table 7 shows the results. As is clear from this table, the results of concentration stability are poor and there is a practical problem overall,
And the result was obtained.

[0065]

[Table 7] Example 2 In the same manner as in Experimental Example 2, a charge injection preventing layer and a photoconductive layer were laminated on a cylindrical conductive substrate using the plasma CVD apparatus under the conditions shown in Table 1, and then a surface protective layer was deposited under the conditions shown in Table 6. And
An electrophotographic photoreceptor was manufactured.

Next, the photoreceptor was also converted to a copier CLC1000 modified by Canon (process speed 135).
mm / sec), and a continuous paper passing durability test of 30
The measurement was performed on 100,000 sheets (4.3 million rotations), and the wear amount was measured and the image was evaluated. The hardness of the surface protective layer of the photoconductor for Bk printing is Ha, and the hardness of the surface protective layer of the other photoconductor for printing is Hb.
The hardness ratio Ha / Hb was 1.5.

In the image evaluation, the high-humidity flow and the density stability during continuous printing were similarly evaluated.

Table 8 shows the results obtained by the above evaluation.

In Table 8, the symbol: Δ: excellent,
Δ: No problem in practical use, ×: Problem in practical use.

As is evident from the table, the results of the system of the present example were generally excellent.

Comparative Example 4 The life, image deletion, and density stability when the hardness ratio Ha / Hb was set to 1.0 were evaluated in the same manner as in Example 2. Table 8 shows the results. As is clear from this table, the result was that the life was poor and there was a practical problem overall.

Comparative Example 5 The life, image flow, and density stability when the film thickness ratio Ta / Tb was 3.5 were evaluated in the same manner as in Example 2. Table 8 shows the results. As is apparent from this table, although the result of the image deletion was slightly poor, it was at a level where there was no problem in practical use, and the result was that there was no problem in practice overall. In Table 8, the symbols have the same meaning as in Table 7.

[0073]

[Table 8] Examples 3 to 6 In the same manner as in Examples 1 and 2, a photoreceptor with further changed conditions was manufactured, and the results of evaluation by a 1.5 million-sheet durability test are shown in Table 9. In Table 9, the symbol ◎ indicates particularly excellent, and the other symbols have the same meanings as in Tables 7 and 8.

[0074]

[Table 9] Comparative Examples 6 to 8 In the same manner as in Examples 1 and 2, photoconductors were manufactured under further different conditions, and the evaluation results are shown in Table 10. The symbols in Table 10 have the same meaning as in Table 9.

[0075]

[Table 10]

[0076]

The electrophotographic apparatus having a plurality of photoreceptors according to the present invention provides a high quality image even when used for a long time without the life of a specific photoreceptor being shorter than that of the others. This has made it possible to reduce running costs and resource consumption. In addition, since the photoreceptor group for an electrophotographic apparatus having a plurality of photoreceptors according to the present invention has a uniform photoreceptor life, when mounted on the electrophotographic apparatus, the apparatus can achieve high reliability and resource saving. .

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an amorphous silicon photoconductor used in the present invention.

FIG. 2 is a diagram showing a relationship between hardness and a wear amount.

FIG. 3 is a diagram showing the results of Experimental Example 1.

FIG. 4 is a diagram showing the results of Experimental Example 1.

FIG. 5 is a diagram showing the results of Experimental Example 1.

FIG. 6 is a diagram showing the results of Experimental Example 2.

FIG. 7 is a diagram showing the results of Experimental Example 2.

FIG. 8 is a schematic sectional view showing an example of a conventional electrophotographic color image forming apparatus.

[Explanation of symbols]

 Pa to Pd Image forming unit 1a to 1d Photoreceptor drum 2a to 2d Primary charger 3a to 3d Image exposing device 4a to 4d Developing unit 5a to 5d Cleaner 6a to 6d Transfer charger 7 Fixing unit 8 Recording material carrying belt 13 Registration roller P Recording material 301 Conductive substrate 302 Photoconductive layer 304 Surface protective layer 305 Charge injection blocking layer

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Koji Yamazaki 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H027 HB02 HB14 2H030 AB02 BB02 BB23 BB71 2H068 DA05 DA07 DA12 DA17 DA20 FB13

Claims (14)

[Claims] 1. An electrophotographic apparatus comprising a plurality of photoconductors, wherein each photoconductor has a surface protective layer made of an amorphous material laminated on a photoconductive layer containing at least amorphous Si. An electrophotographic apparatus, wherein the film thickness of the surface protective layer of at least one photoconductor is different from the film thickness of the surface protective layers of the other photoconductors so that the lifespans of the photoconductors are uniform. 2. The photoconductor according to claim 1, wherein the surface protective layer comprises at least a-SiC: H, a-SiN: H, aC: H and a
2. The electrophotographic apparatus according to claim 1, comprising any one of -CN: H. 3. The electrophotographic apparatus according to claim 1, wherein the thickness of the surface protective layer of the at least one photosensitive member is larger than the thickness of the surface protective layer of the other photosensitive member. 4. When the initial thickness of the surface protective layer of the at least one photoreceptor is Ta and the initial thickness of the surface protective layer of the other photoreceptor is Tb, 1.1 ≦ Ta / Tb. ≦ 2.
0 and 650 nm ≦ [Ta or Tb] ≦ 1
The electrophotographic apparatus according to claim 3, wherein the thickness is 300 nm. 5. A method according to claim 1, wherein said means for rubbing the surface protective layer of the photoreceptor comprises one of a cleaning blade, a mag brush, a transfer roller, and an elastic cleaning roller, or a combination thereof. An electrophotographic apparatus according to the above. 6. An electrophotographic apparatus comprising a plurality of photosensitive members, wherein each photosensitive member has a surface protective layer made of an amorphous material laminated on a photosensitive layer containing at least amorphous Si. An electrophotographic apparatus, wherein the hardness of the surface protective layer of at least one photosensitive member is different from the hardness of the surface protective layer of another photosensitive member so that the lifespans of the members are uniform. 7. The photoconductor according to claim 1, wherein the surface protective layer comprises at least a-SiC: H, a-SiN: H, aC: H and a
7. The electrophotographic apparatus according to claim 6, comprising any one of -CN: H. 8. The electrophotographic apparatus according to claim 6, wherein the hardness of the surface protective layer of the at least one photoconductor is higher than the hardness of the surface protective layer of the other photoconductor. 9. When the hardness of the surface protective layer of the one photoreceptor is Ha and the hardness of the surface protective layer of the other photoreceptor is Hb, 1.1 ≦ Ha / Hb ≦ 3.0. There and
3000 N / mm ² ≤ [Ha or Hb] ≤ 1300 N
9. The electrophotographic apparatus according to claim 8, wherein the ratio is / mm ² . 10. The apparatus according to claim 6, wherein said means for rubbing the surface protective layer of the photoconductor comprises one of a cleaning blade, a mag brush, a transfer roller, and an elastic cleaning roller, or a combination thereof.
An electrophotographic apparatus according to any one of claims 1 to 9. 11. A photoreceptor group used for an electrophotographic apparatus having a plurality of image forming units, wherein each photoreceptor has a surface protective layer made of an amorphous material laminated on a photosensitive layer containing at least amorphous Si. Wherein the thickness of the surface protective layer of at least one of the photoconductors is different from the thickness of the surface protective layer of the other photoconductor so that the life of the photoconductor group is uniform. Body group. 12. When the initial thickness of the surface protective layer of the at least one photoreceptor is Ta and the thickness of the surface protective layer of the other photoreceptor is Tb, 1.1 ≦ Ta / Tb ≦ 2.0
650 nm ≦ [Ta or Tb] ≦ 13
The photoconductor group according to claim 11, which has a thickness of 00 nm. 13. A photoreceptor group used for an electrophotographic apparatus having a plurality of image forming units, wherein each photoreceptor has a surface protective layer made of an amorphous material laminated on a photosensitive layer containing at least amorphous Si. Wherein the hardness of the surface protective layer of at least one of the photoconductors is different from the hardness of the surface protective layer of the other photoconductor so that the service life of the photoconductor group is uniform. Body group. 14. When the initial hardness of the surface protective layer of the at least one photosensitive member is Ha and the hardness of the surface protective layer of the other photosensitive member is Hb, 1.1 ≦ Ha / Hb ≦ 3. 0
And 3000 N / mm ² ≤ [Ha or H
The photoconductor group according to claim 13, wherein b] ≦ 13000 N / mm ² .