JP2000187345A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain such a high resolution as >=600 dpi. SOLUTION: An electric charge injection blocking layer comprising a-Si and a photoconductive layer are successively laminated on an electrically conductive substrate. Boron atoms are incorporated into the photoconductive layer in a proportion of 0.08-0.7 ppm to silicon atoms to obtain a photoreceptor 8. This photoreceptor 8, a corona charger 9, an exposure unit 10 which irradiates light at >=600 dpi dot density, a developing machine 12, a transfer unit 14, a cleaning means 15 and a de-electrifying means 16 are disposed to obtain the objective image forming device 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus equipped with an electrophotographic photosensitive member made of hydrogenated amorphous silicon and exposed by an LED head or laser light.

[0002]

2. Description of the Related Art A photoreceptor using amorphous silicon (hereinafter, amorphous silicon is abbreviated as a-Si) as a photoconductive layer has already been commercialized, but the a-Si photoreceptor is formed on a conductive substrate. A-Si by glow discharge decomposition
A charge injection blocking layer made of and a photoconductive layer are sequentially laminated, and amorphous silicon carbide (hereinafter a-Si
C) (which is abbreviated as C), and a technique applied to a photoconductor for a semiconductor laser printer with this configuration has been proposed (Japanese Patent Publication No. 8-14).
No. 706).

According to this technique, when forming a photoconductive layer by a glow discharge method, a flow rate ratio of diborane to silane [B ₂
By setting H ₆ ] / [SiH ₄ ] to 1 to 10 ppm,
There is an effect that charge retention is improved, and sensitivity to long wavelength light of 700 nm or more is increased.

On the other hand, in an a-Si photosensitive member in which a charge blocking layer (charge injection blocking layer), a charge transport layer, a charge generation layer (photoconductive layer) and a surface protection layer are sequentially laminated,
A technique has been proposed in which the boron doping level of the photoconductive layer is increased toward the surface protective layer and decreased toward the charge transport layer, thereby increasing the sensitivity and reducing the residual potential, thereby eliminating image blurring (image blurring). (Japanese Unexamined Patent Application Publication No.
No. 2,865), the application of this a-Si photosensitive member to a photosensitive member for a semiconductor laser printer is not specified.

[0005]

As described above, in the conventional a-Si photosensitive member for a semiconductor laser printer,
The a-Si photoconductive layer has been doped with boron in order to improve charge retention and photosensitivity.

However, despite the recent demand for high-density images with a reduced dot diameter for photoconductors for semiconductor laser printers, the relationship between boron content and dot density has not yet been studied. .

In view of the above circumstances, the present inventor has conducted intensive studies on the conditions for high-density images, and has found that boron atoms are contained in the a-Si photoconductive layer in an amount of 0.08 to 0.7 with respect to silicon atoms.
It has been found that when contained in ppm, it is suitable for a dot density of 600 dpi or more.

Accordingly, the present invention has been completed based on the above findings, and its purpose is to provide an a
An object of the present invention is to provide an image forming apparatus having a high quality and high density image by forming a Si layer structure.

It is another object of the present invention to provide an image forming apparatus having a high resolution and an improved charging ability.

[0010]

According to the present invention, there is provided an image forming apparatus comprising: a charge injection preventing layer made of a-Si on a conductive substrate;
A photoconductor in which a photoconductive layer and a surface protection layer are sequentially laminated, a charging unit for applying a charge to the surface of the photoconductor, an exposure unit for irradiating the charged area of the photoconductor with light with a dot density of 600 dpi or more; Developing means for forming an electrostatic latent image on the surface of the photoreceptor by the charging means and exposure means, and forming a toner image corresponding to the electrostatic latent image on the surface of the photoreceptor; and transferring the toner image to a transfer-receiving material Transfer means, a cleaning means for removing the residual toner on the photoreceptor surface after the transfer, and a charge removing means for removing the residual electrostatic latent image after the transfer, and the boron atom (B) is added to the photoconductive layer. It is characterized in that it is contained at a ratio of 0.08 to 0.7 ppm with respect to silicon atoms (Si).

[0011]

Diagram 1 of the embodiment of the invention photoreceptor is a layer structure of the photosensitive member 1 according to the embodiment of the invention,
A charge injection blocking layer 3 made of a-Si and a photoconductive layer 4 made of a-Si are sequentially laminated on a conductive substrate 2 by a glow discharge decomposition method, and a surface protective layer 5 is formed on the photoconductive layer 4.
Are laminated.

Copper, brass, SUS, A
Metallic conductors such as 1 and Ni, or insulators such as glass and ceramic, each of which has a surface coated with a conductive thin film. The conductive substrate 2 may be a sheet-shaped, belt-shaped or web-shaped flexible conductive sheet, such as a metal sheet such as SUS, Al, or Ni, or a polymer resin film such as polyester, nylon, or polyimide. A metal such as Al or Ni, or a transparent conductive material such as indium tin oxide (ITO) or an organic conductive material is coated thereon by vapor deposition or the like, and is subjected to a conductive treatment.

The charge injection blocking layer 3 and the surface protection layer 5 are a
-Si, a-SiC, amorphous silicon nitride, amorphous silicon oxide, etc. by glow discharge decomposition, vacuum evaporation, active reactive evaporation, ion plating, RF sputtering, DC sputtering, RF magnetron sputtering, DC A film is formed by a magnetron sputtering method, a thermal CVD method, or the like. The charge injection blocking layer 3 may be doped with a group IIIa element and / or a group Va element as a valence electron controlling impurity.

When the charge injection blocking layer 3 contains oxygen or nitrogen, the forbidden band width is widened, whereby the function of preventing charge injection can be increased, and the barrier can be increased. Thus, the adhesiveness with the substrate can be improved. However, if only oxygen is used, it reacts with the silane gas to easily cause an explosion. Therefore, it is preferable to use inert nitrogen together. In practice, nitrogen monoxide (NO) gas or the like is used.

Preferably, the photoconductive layer 4 contains boron atoms (B) in a range of 0.08 to 0.7 ppm with respect to silicon atoms (Si), and the atomic ratio B / Si is less than 0.08 ppm. In the case of (1), the outline of the dots starts to blur, and when the concentration exceeds 0.7 ppm, the charging ability is attenuated. The B atom-containing region defined as described above may be contained in the entire photoconductive layer 4 or may be contained in the surface protective layer 5 in the photoconductive layer 4.
The region adjacent to the side may be a B atom-containing region. In the B atom-containing region, the atomic ratio B / Si is 0.08 to
The range is 0.7 ppm. In that case, the content of B atoms in other regions may be lower or higher than the above B atom content.

Thus, according to the photoreceptor 1 according to the present invention,
By limiting and containing B atoms in the photoconductive layer as described above, it is suitable for high resolution with a dot density of 600 dpi or more,
It becomes an image forming apparatus for high-density images.

When the surface protective layer 5 is formed of a-SiC, the charging ability and the resolution are improved, but carbon is further provided between the photoconductive layer 4 and the surface protective layer 5 as compared with the surface protective layer 5. By interposing an intermediate layer formed with a-Si containing a small amount, the charging ability is further improved.

FIG. 3 and FIG. 4 show the carbon content distribution of such an intermediate layer. In these figures, the abscissa indicates the layer thickness direction, a indicates the interface with the photoconductive layer 4, and b indicates the interface with the surface protective layer 5. The vertical axis is the carbon content.

FIG. 3 shows a case where the methane gas or the like is gradually introduced and stopped without stopping the glow discharge during the film formation of the photoconductive layer 4 with, for example, silane gas. FIG. 4 shows the photoconductive layer 4
Film formation discharge, and then introduce methane gas etc.
This is a case where it is further increased gradually. In particular, by providing an interface a having a step as shown in FIG. 4, the charging ability was increased, and thereby higher resolution could be obtained. Further, when the C / Si atomic ratio at the interface a (site a) is 50% or less, preferably 3 to 35%, high charging ability is obtained.

Further, when the surface protection layer 5 is formed of a-SiC, the thickness of the layer is 10,000 to 20,000.
By setting the angle to 0 °, it is desirable in that there is no decrease in density, the roughness of a solid black image can be suppressed, and solid black having a uniform density can be printed. In addition,
Here, the crispness refers to a phenomenon in which, when actual printing is performed, the solid black density is not uniform, and places with low density are formed in some places.

[0021] Configuration FIG. 2 of the image forming apparatus is an image forming apparatus 7 equipped with a printer constituting the photosensitive member of the present invention, 8 denotes a photosensitive member, a corona charger 9 to the peripheral surface of the photoconductor 8, Exposure device 10 (LED head or laser light) for irradiating light after the charging, developing device 12 provided with toner 11 for forming a toner image on the surface of photoconductor 8, and transferring the toner image to transfer material 13 A transfer unit 14 for transferring, a cleaning unit 15 for removing residual toner on the surface of the photoconductor after the transfer, and a charge removing unit 16 for removing a residual electrostatic latent image after the transfer are provided. Reference numeral 17 denotes a fixing device for fixing the toner image transferred to the transfer material 13 by heat or pressure.

In the Carlson method, the following processes are repeated. The peripheral surface of the photoconductor 8 is charged by the corona charger 9. By irradiating the image with light at a dot density of 600 dpi or more by the exposure device 10, an electrostatic latent image as a potential contrast is formed on the surface of the photoconductor 8. This electrostatic latent image is subjected to dry development or wet development by the developing device 12. Due to this development, the toner adheres to the surface of the photoreceptor by electrostatic attraction with the electrostatic latent image and is visualized. The toner image on the surface of the photoreceptor is electrostatically transferred from the back surface of the transfer material 13 such as paper by applying an electric field having a polarity opposite to that of the toner, whereby an image is obtained on the transfer material 13. The cleaning unit 15 mechanically removes residual toner on the surface of the photoconductor. The entire surface of the photoconductor is exposed to intense light, and the remaining electrostatic latent image is removed by the charge removing means 16.

[0023]

(Example 1) Film forming conditions as shown in Table 1 on a cylindrical substrate (outer diameter 100 mm, longitudinal dimension 364 mm) made of Al having a purity of 99.9% (this condition is within one chamber). The charge injection blocking layer 3, the photoconductive layer 4 (containing boron atoms in a B / Si atomic ratio of 0.2 ppm) and the surface protective layer 5 were laminated by the glow discharge decomposition method. In addition, → shown in the gas amount and the film formation rate of the surface protective layer 5 indicates the first value and the last value when it changes with time.

[0024]

[Table 1]

Further, an intermediate layer shown in FIG. 4 was interposed in the layer structure shown in Table 1. The conditions for forming the intermediate layer are as shown in Table 2. In the same table, the film forming conditions for the portion a and the portion t (shown in FIG. 4) between the interface a with the photoconductive layer 4 and the interface b with the surface protective layer 5 are also shown. The composition ratio is gradually changed from to the part b.

[0026]

[Table 2]

Then, various photoconductors (samples No. 1 to No. 9) in which the thickness of the photoconductive layer 4 was changed in various ways were prepared and mounted on the image forming apparatus 7, and the dot diameter and the resolution were measured. When the charging ability was determined, the results shown in Table 3 were obtained.

The resolution was evaluated based on two criteria of ○ and ×. The mark “○” indicates a case where a resolution of 600 dpi or more was obtained, and the mark “X” indicates a case where such a high resolution was not obtained.

[0029]

[Table 3]

As is clear from this table, Sample No. 1
When the dot diameter is 42 μm or less as shown in FIGS.
It can be seen that high resolution was obtained with a thickness of 20 μm or less.

(Example 2) Next, with respect to the photoreceptor prepared in (Example 1), the CH ₄ / SiH ₄ gas flow ratio at the portion a of the intermediate layer was changed in various ways (with this gas flow ratio). A film was formed for 40 seconds, and the layer thickness x (portion a to site s) in FIG.
Various photoconductors were prepared in which the C / Si atomic ratio at the site a was variously defined, and the layer thickness of the photoconductive layer 4 was varied in various ways, and their resolution was measured. However, the results shown in Table 4 were obtained. However, C / S
When the i atomic ratio was zero, the intermediate layer shown in FIG. 3 was formed by gradually increasing the methane gas from the site s.

[0032]

[Table 4]

As is clear from the results in Table 4, even in the case of the intermediate layer (C / Si atomic ratio = 0%) shown in FIG. 3, by reducing the thickness of the photoconductive layer 4 to 5 μm,
A resolution of 0 dpi or more was obtained. Further, when the photoconductive layer 4 is formed with the intermediate layer of FIG.
m, thereby increasing the charging ability to 630 V.

(Example 3) The intermediate layer shown in FIG. 4 was interposed, and the gas flow ratio of CH ₄ / SiH ₄ at site a was set to 1.00 (C / Si atomic ratio was 22.8%). Various photoconductors were prepared by changing the film formation time in various ways (indicated by the layer thickness x in FIG. 4) and further changing the layer thickness of the photoconductive layer 4 in various ways, and mounted on the image forming apparatus 7. When the dot diameter and the resolution were determined, the results shown in Table 5 were obtained.

[0035]

[Table 5]

As is clear from the results shown in Table 5, by setting the layer thickness range x to 40 ° or 80 °, the photoconductive layer 4 could be increased to a thickness of 40 μm, and the charging ability could be increased.

(Example 4) With respect to the photoreceptor of (Example 3), the gas flow ratio of CH ₄ / SiH _{4 at} the portion a was 1.00.
(C / Si atomic ratio is 22.8%), the film formation time is 40 seconds (layer thickness x: 160 °), and the photoconductive layer 4 has a thickness of 20 μm. Various photoconductors in which the amount of boron of Example 4 was changed in various ways were prepared (Sample N).
o. 10-No. 19), each was mounted on the image forming apparatus 7, and the dot diameter and the resolution were determined. The results shown in Table 6 were obtained. The amount of boron was measured by SIMS, and based on the measurement result, B ₂ H ₆ / Si
By multiplying the H ₄ gas flow ratio by 0.8, B / Si
The atomic ratio was used. In addition, the mark “△”, which is the evaluation of the resolution, is a case where there is a practical problem due to slight deterioration.

[0038]

[Table 6]

Sample No. of the present invention 13-No. Regarding No. 16, a resolution of 600 dpi or more was obtained, and
In addition, the charging ability was increased, the outline of the dots was not blurred, and no fogging occurred. However, the sample No. 10
No. In No. 12, the outline of the dots was blurred, and so-called "blur" occurred. In addition, the sample No. In Nos. 17 to 19, fogging occurred due to the decrease in charging ability.

Example 5 Sample No. of the present invention 4 (layer thickness of photoconductive layer 4: 20 μm, C / Si atomic ratio at site a: 11.6%, layer thickness x: 80 °), the thickness of the surface protective layer was changed in any number of ways, and the degree of black stickiness was changed. Was measured, the results shown in Table 7 were obtained.

○ indicates a case where an excellent image was obtained without a rough image and no decrease in density, △ indicates a case where the image was slightly deteriorated, and X indicates a case where the image was rough or the density was reduced. Is remarkable and there is a problem in practical use.

[0042]

[Table 7]

Sample No. of the present invention 24-No. For 26, the thickness of the a-SiC surface protective layer was set to 10,000 to
By making it 20,000Å, it will not be a Kasatsu image,
Further, an excellent image without a decrease in density was obtained.

[0044]

As described above, according to the image forming apparatus of the present invention, since the a-Si photoconductive layer contains B atoms at a ratio of 0.08 to 0.7 ppm with respect to Si atoms, 6% is obtained.
High resolution of 00 dpi or more was obtained.

In the present invention, the photoconductive layer and the a-
By providing an intermediate layer formed of a-Si containing a smaller amount of carbon than the surface protective layer 5 between the SiC surface protective layer and the surface protective layer 5, the level of the carbon can be reduced particularly at the interface with the photoconductive layer. , The charging ability could be increased with high resolution. Furthermore,
The thickness of the a-SiC surface protective layer is from 10,000 to 20,000.
By setting the angle to 00 °, an excellent image was obtained without a rough image and without a decrease in density.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a layer configuration of a photoreceptor according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of an image forming apparatus of the present invention.

FIG. 3 is a cross-sectional view illustrating a carbon amount distribution of an intermediate layer in the photoconductor according to the embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a carbon amount distribution of an intermediate layer in the photoreceptor according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 8 Photoreceptor 2 Substrate 3 Photosensitive layer 5 Photoconductive layer 6 Surface protective layer 7 Image forming apparatus 9 Corona charger 10 Exposure device 11 Toner 12 Developing machine 13 Transfer material 14 Transfer device 15 Cleaning means 16 Static elimination means

Claims (1)

[Claims] 1. A photoconductor in which a charge injection blocking layer made of amorphous silicon, a photoconductive layer, and a surface protection layer are sequentially laminated on a conductive substrate, a charging unit for applying a charge to the surface of the photoconductor, and a photoconductor. Exposure means for irradiating the charged area with light at a dot density of 600 dpi or more, and forming an electrostatic latent image on the surface of the photoreceptor by the charging means and the exposure means, and forming a toner image corresponding to the electrostatic latent image Developing means for forming on the surface of the photoreceptor, transfer means for transferring the toner image to a material to be transferred, cleaning means for removing residual toner on the surface of the photoreceptor after the transfer, and removal of a residual electrostatic latent image after the transfer An image forming apparatus, wherein boron atoms are contained in the photoconductive layer by 0.08 to silicon atoms.
An image forming apparatus characterized in that it is contained at a ratio of 0.7 ppm.