JPH06250425A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body which does not cause fog in a picture image, image flowing nor black spots. CONSTITUTION:The photosensitive body has a structure comprising an amorphous silica (a-Si) carrier injection preventing layer 5, a-Si photoconductive layer 6, and surface layer 7 successively formed on a conductive substrate 4. The atomic density of each layer is specified as follows with the unit of atoms/cm<3>. The carrier preventing layer: <=5.5X10<22> in the amorphous state (a-state) and >=2.0X10<21> for dangling bond compensation (D-compensation). Photosensitive layer: <=5.0X10<22> in the a-state and >=2.0X10<21> for D- compensation. Surface layer: <=3.0X10<22> in at least one of a-state Si and Ge, <=5.0X10<22> in at least one of a-state N and C, and >=5.5X10<22> for D- compensation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member comprising an amorphous silicon photoconductive layer.

[0002]

2. Description of the Related Art Recently, an amorphous silicon photoconductive layer (hereinafter, amorphous silicon is abbreviated as a-Si).
The electrophotographic photosensitive member made of is commercialized, and the production amount thereof is increasing year by year.

The basic structure of this a-Si type photosensitive member is shown in FIG.
As shown in FIG. 1, an a-Si based photoconductive layer 2 is formed on the conductive substrate 1.
Was formed, and a surface layer 3 made of, for example, amorphous silicon carbide was laminated to increase the surface hardness. On the other hand, when the electrophotographic photoreceptor of this structure is used under high temperature and high humidity, Image deletion (so-called so-called blurring) occurred, which hindered practical use.

To solve this problem, a heater is provided in the vicinity of the electrophotographic photosensitive member and the photosensitive member is heated to 35 to 50 ° C.
Then, the water content on the surface of the photoconductor is reduced to prevent the occurrence of image deletion.

On the other hand, it is also known that the charged product adhering to the surface of the photoconductor absorbs moisture under high temperature and high humidity and causes the image deletion, and the efficiency is improved. A cleaning process has been developed that can electrically remove charged products.

However, even in the a-Si type photoconductor having the above-mentioned constitution and the cleaning process, the a-S
After repeating printing at room temperature and humidity with a device equipped with an i-type photoconductor, turn off the power (heater for the photoconductor heating
FF) After that, leave it under high temperature and high humidity for several hours (or overnight), then turn on the power again (O of the heater for heating the photoconductor).
N) When an image is formed, there is a problem that image fogging occurs on the first tens to hundreds of sheets.

In order to solve such a problem, the present inventor has already disclosed in Japanese Patent Application No. 4-247730 that the atomic density of the surface layer 3 in the amorphous state is 6.5 × 10 ²² atoms / c.
If the density is m ³ or less, or if the density of at least one atom of hydrogen or fluorine that compensates for the dangling bond is 5.0 × 10 ²² atoms / cm ³ or more, image fogging or image deletion It is proposed that will not occur.

[0008]

However, by using the electrophotographic photosensitive member proposed above and by providing a heater near the electrophotographic photosensitive member, the photosensitive member is heated to 35 to 50 ° C. Even if the water content on the surface of the photoconductor is reduced, after further repeating printing durability under high temperature and high humidity with a device equipped with the a-Si photoconductor, turn off the power (heater for photoconductor heating OFF). After that, the process of leaving it under high temperature and high humidity for several hours (or overnight) and turning on the power again (turning on the heater for heating the photoconductor) is repeated several times, and an image is formed immediately after turning on the power. Upon careful observation of the images, it was found that the first few images had light image smearing and light fog. Moreover, it was also found that black spots were generated in the image.

The image deletion and fog are gradually recovered by printing several sheets to several tens of sheets after the power is turned on. There are cases where the black spots are gradually recovered and cases where they are not easily recovered.

As described above, when the printer is operated in a more severe environment of high temperature and high humidity, a good image cannot be obtained when the power is turned off in the environment and the power is turned on the next day for printing. There was a problem.

[0011]

The electrophotographic photoreceptor of the present invention comprises a conductive substrate on which silicon (Si) or germanium (G) is formed.
e), an atom of at least one of oxygen (O), nitrogen (N) and carbon (C) in an amorphous state, and a carrier injection blocking layer composed of hydrogen or fluorine atoms compensating for dangling bonds of the atoms. Laminate the photosensitive layer in sequence,
A structure in which a surface layer composed of atoms in an amorphous state composed of at least one of silicon, germanium, nitrogen and carbon and atoms of hydrogen or fluorine compensating for dangling bonds of the atoms is laminated on the photosensitive layer. The atomic density of each layer is set as follows.

Carrier injection blocking layer Atomic density in amorphous state: 5.5 × 10 ²² atoms / cm ³ or less Density of dangling bond compensating atoms: 2.0 × 10 ²¹ atoms / cm ³ or more Atomic density of photosensitive layer in amorphous state: 5.0 × 10 ²² atoms / cm ³ or less Density of atoms for dangling bond compensation: 2.0 × 10 ²¹ atoms / cm ³ or more Surface layer in amorphous state Density of at least one atom of Si or Ge: 3.0 × 10 ²² atoms / cm ³ or less Density of at least one atom of N or C in an amorphous state 5.0 × 10 ²² atoms / cm ³ or less Density of dangling bond compensating atoms: 5.0 × 10 ²² atoms / cm ³ or more

[0013]

Although the present inventor cannot escape the realm of reasoning, as a result of a multi-faceted study of the causes of light image blurring and light fog in the image and the occurrence of black spots in the image, high temperature and high humidity When left for a long time and then turned on the power to immediately start printing (printing endurance), the temperature of the photoconductor does not rise immediately after that, and as a result, it is absorbed in each layer of the photoconductor. The remaining water remains and each layer is in an electrically low resistance state as a result, and as a result, the charging potential does not become high, which causes light image deletion and light fogging, and I think that black spots will occur. Further, as a proof of this inference, the present inventor has confirmed by experiments that the black dots are a-Si regions containing a large amount of water.

Based on this inference, the present inventor sets the carrier injection blocking layer to have a relatively coarse film structure by setting the atomic density of the amorphous state to 5.5 × 10 ²² atoms / cm ³ or less. The water content of this layer is low.

Further, by setting the atomic density of the photosensitive layer in the amorphous state to 5.0 × 10 ²² atoms / cm ³ or less to set a relatively rough film structure, the water content of this layer also decreases.

Furthermore, the density of dangling bond compensating atoms in both the carrier injection blocking layer and the photosensitive layer is 2.0 ×.
If it is 10 ²¹ atoms / cm ³ or more, in a rough film structure, atoms having a small covalent bond radius are uniformly distributed so as to fill the gaps, and further, there is a water repellent action that repels water, which results in adsorption / adsorption. It reduces the amount of water trying to enter.

Further, 5.0 × 10 5 mixed atoms composed of oxygen (O) or nitrogen (N) or carbon (C) containing at least oxygen (O) are provided in both the carrier injection blocking layer and the photosensitive layer.
^When it is contained at ²¹ atoms / cm ³ or less, the hygroscopic silicon oxide-based SiO (N: C) compound is reduced, and the water content is reduced even when it is placed under high temperature and high humidity.

Further, in the surface layer of the electrophotographic photosensitive member having the above-mentioned constitution, at least one atom of Si or Ge in an amorphous state containing 3.0 × 10 ²² atoms / cm ³ or less and 5. By combining at least one atom of amorphous N or C contained at 0 × 10 ²² atoms / cm ³ or less, a surface layer having a relatively rough film structure is laminated. It is considered that the water content of is reduced. For this reason as well, the present inventor cannot escape the realm of inference. However, when the heater for heating the photoconductor is turned off, adsorption and intrusion of water are suppressed, and immediately after the heater for heating the photoconductor is turned on, It is considered that adsorption and release of invading water are accelerated, and thus fogging of an image is less likely to occur. As a result, in the case of a device equipped with a conventional a-Si-based photoconductor, an image fog is applied to the first several tens to several hundreds of sheets by a printing durability test in which printing is repeated under normal temperature and humidity. Although the surface potential was lowered by several tens of V, the potential was not lowered and the image fogging did not occur. as a result,
Even when a more severe printing durability test was performed in which the printing durability was repeated under high temperature and high humidity, the surface potential did not decrease and the image fogging did not occur.

In addition, the inventor of the present invention deduces that the reason why good results were obtained for the surface layer of the electrophotographic photosensitive member having the above-mentioned constitution is as follows. That is, it is considered that this is caused by mixing Si or Ge, which is weak in ozone (oxidation), with N or C, which is strong in ozone (oxidation), but in addition, the light transmittance is increased to obtain high sensitivity (optical energy Egopt . 2.2eV or more), the residual potential can be reduced to secure the concentration (optical energy Egopt. 3.0).
eV or less), and the reason why it is possible to secure the necessary wear resistance by increasing the hardness due to the alloying.

Moreover, according to the surface layer, the density of at least one atom of hydrogen or fluorine that compensates for dangling bonds is 5.0 × 10 ²² atoms / cm ³ or more, so that a rough film structure is obtained. On the other hand, atoms with a small covalent radius are evenly distributed so as to fill the gap, and there is also a water-repellent effect that repels these waters, and these uniform distribution and water-repellent effect are effectively combined. It is considered that the amount of water absorbed and absorbed will decrease.

According to the electrophotographic photosensitive member having the above-mentioned structure, the density of atoms in the amorphous state is lowered as compared with each layer of the conventionally known electrophotographic photosensitive member, and the surface layer having a rough film structure is laminated. In the case of manufacturing by the glow discharge decomposition method, depending on the film forming conditions, it can be formed by increasing the film forming rate, increasing the gas pressure, and decreasing the high frequency power as compared with the conventional case.

Further, under such film forming conditions, in order to further increase the density of at least one atom of hydrogen or fluorine that compensates for dangling bonds to a predetermined content or more, film forming is performed as compared with the conventional method. It can be formed by increasing the speed and setting the substrate temperature lower.

[0023]

EXAMPLES Hereinafter, the case where the electrophotographic photosensitive member of the present invention is manufactured by the glow discharge decomposition method will be described as an example. Figure 1
Shows the layer structure of the electrophotographic photosensitive member produced in this example, and FIG. 2 shows the glow discharge decomposition apparatus used in this example.

First, in FIG. 1, a carrier injection blocking layer 5, an a-Si based photoconductive layer 6 and a surface layer 7 are sequentially laminated on a conductive substrate 4, and in this example, the conductive substrate 4 is used.
A carrier injection blocking layer 5 made of aluminum metal.
The surface layer 7 is formed of an amorphous silicon carbide layer (hereinafter, amorphous silicon carbide is abbreviated as a-SiC) of a -Si-based layer. However, not limited to this example, the following materials can be used for each member.

The conductive substrate 4 may be composed of a conductive member such as an aluminum alloy, or a conductive film formed on the surface of resin or glass by vapor deposition or the like.

The carrier injection blocking layer 5 is made of an a-Si base material and contains hydrogen and fluorine.
It may be constituted by containing at least one element selected from Group I, Group IV, and Group V and, if necessary, containing carbon, oxygen, nitrogen and the like.

The surface layer 7 uses hydrogen (H) or fluorine (F) as a dangling bond compensating element.
-SiC: F, a-SiC: H: F, a-SiCN:
H, a-SiCGe: H, a-SiN: H, a-Si
N: F, a-SiN: H: F, a-C: H, a-C:
F, a-C: H: F, a-CN: H, a-Ge: H, a
-Ge: F, a-SiGe: H, a-SiGe: F, a
It is considered that even an amorphous alloy layer such as -SiGe: H: F (a- represents amorphous) has the same operational effect.

The thickness of each layer may be set as follows. According to the Carlson process, the development potential is generally 400 to 800 V, and accordingly, the carrier injection blocking layer 5 is 0.8 to 1.6 μm or more, and the a-Si based photoconductive layer 6 is 28 to 56 μm or more. is necessary.

Further, in the so-called optical backside recording system in which the conductive substrate 4 is made of a light-transmissive substrate and light is emitted from the substrate, the developing potential is 30 to 100 V, and accordingly carrier injection is performed. The blocking layer 5 is 0.06 to
0.4 μm or more, and the a-Si-based photoconductive layer 6 needs to be 2 to 7 μm or more.

Next, the structure of the glow discharge decomposition apparatus 8 of FIG. 2 will be described. In the figure, 9 is a cylindrical metal reactor, 10
Is a cylindrical conductive substrate support for mounting the photosensitive drum,
Reference numeral 11 is a substrate heating heater, 12 is a cylindrical glow discharge electrode plate used for film formation of a-Si, a gas ejection port 13 is formed in the electrode plate 12, and 14 is a reaction gas. A gas inlet for introducing gas into the furnace, 15 for discharging residual gas of the gas exposed to glow discharge, and 16 for the substrate support 10 and the electrode plate 12 for glow discharge. It is a high frequency power source that generates glow discharge between the two. Further, the reaction furnace 9 has a cylindrical body 9a.
And a lid 9b and a bottom 9c, and an insulating ring 9d is provided between the cylinder 9a and the lid 9b, and between the cylinder 9a and the bottom 9c. As a result, one terminal of the high frequency power source 16 is electrically connected to the glow discharge electrode plate 12 via the cylindrical body 9a, and the other terminal is electrically connected to the substrate support body 10 via the lid body 9b and the bottom body 9c. ing. In addition, the motor 1 attached to the lid 9b above
The substrate support 10 is rotationally driven by the rotary shaft 18 by the rotary shaft 7, and the substrate 4 also rotates accordingly.

Using this glow discharge decomposition apparatus 8, aS
In the case of producing an i photoconductor drum, the drum-shaped substrate 4 for a-Si film formation is mounted on the substrate support 10, and a-Si generation gas is introduced into the reaction furnace through the gas introduction port 14, This gas is jetted to the surface of the substrate through the gas jet port 13, the substrate is set to a required temperature by the heater 11, and glow discharge is generated between the substrate support 10 and the electrode plate 12. By rotating, an a-Si film can be formed on the peripheral surface of the substrate 4.

(Example 1) In this example, the a-Si type photoconductor A and the photoconductor B having the structure shown in FIG. 1 were formed under the film forming conditions shown in Tables 1 and 2.
Was produced. Each of the photoconductors A and B is composed of the carrier injection blocking layer 5 and the a-Si based photoconductive layer 6 as shown in Table 1. Further, the common surface layer 7 is formed under the film forming conditions as shown in Table 2. And two types of photoconductor A corresponding to
B was produced.

[0033]

[Table 1]

[0034]

[Table 2]

The atomic densities of the carrier injection blocking layer 5 and the a-Si photoconductive layer 6 of these two types of photoconductors A and B are 0.5 μm on the separately prepared conductive substrate. A film was formed as shown in Table 1, a part thereof was cut into 1 cm square, and the analytical value of the layer was determined by RBS (Rutherford backscattering) analysis. Further, the hydrogen atom density was similarly obtained by SIMS (secondary ion mass) analysis method. The results are shown in Table 3.

[0036]

[Table 3]

With respect to the two types of photoreceptor A and photoreceptor B thus obtained, the photoreceptor temperature was set to 45 ° C., and 10,000 sheets were printed at room temperature and normal humidity (33 ° C., 85% RH). After repeating 10,000 copies printing 5 times, it was exposed to high temperature and high humidity (33 ° C, 8
After leaving it for 12 hours at 5% RH) and turning on the power in this state to observe the state of the initial image, the results shown in Table 4 were obtained for image fogging, image deletion, and the presence or absence of black spots. Was given.

In the table, ◯ indicates that the entire surface of the recorded image is good, Δ indicates that part (5% or less) of the recorded image is defective, and x indicates the total area of the recorded image. 5% or more of the cases are defective. Hereinafter, the same evaluation criteria are adopted.

[0039]

[Table 4]

As is clear from these results, the photoconductor A having a low atomic density in the amorphous state and a high density of dangling bond compensating atoms is an excellent photoconductor free from image fogging and image deletion. I understood.

(Example 2) In this example, a-Si type photoconductors C and D having the structure shown in FIG. 1 were manufactured under the film forming conditions shown in Table 5. Each of the photoconductors is composed of a common surface layer 7 as shown in Table 2, but two different types of carrier injection blocking layer 5 and an a-Si based photoconductive layer are formed by changing the film forming conditions as shown in Table 5. 6 is formed, and two types of photoconductors C and D are correspondingly formed.
Was produced.

[0042]

[Table 5]

Atomic densities of oxygen and nitrogen contained in the carrier injection blocking layer 5 and the a-Si photoconductive layer 6 of the two types of photoreceptors C and D were measured in the same manner. The results shown in Table 6 were obtained.

[0044]

[Table 6]

With respect to the two types of photoreceptor C and photoreceptor D thus obtained, the photoreceptor temperature was set to 45 ° C., and 10,000 sheets were printed at room temperature and normal humidity (33 ° C., 85% RH). After repeating 10,000 copies printing 5 times, it was exposed to high temperature and high humidity (33 ° C, 8
When left for 5 hours at 5% RH) and turned on the power in this state to see the state of the initial image, the results shown in Table 7 were obtained for image fogging, image deletion, and the presence or absence of black spots. Was given.

[0046]

[Table 7]

As is clear from this result, the photoconductor C in which the amount of oxygen and nitrogen contained in the carrier injection blocking layer 5 and the a-Si based photoconductive layer 6 is smaller than 5.0 × 10 ²¹ atoms / cm ^3.
It was found that in Example 1, there was no image fogging and image deletion, and an excellent photoconductor in which the generation of black spots was improved was obtained.

Example 3 In this example, the a-Si type photoconductor E and the photoconductor F having the constitution shown in FIG. 1 were formed under the film forming conditions shown in Tables 8 and 9.
Was produced. Each of the photoconductors comprises a carrier injection blocking layer 5 and an a-Si based photoconductive layer 6 as shown in Table 8,
Although it is constituted by the common surface layer 7 as shown in Table 2, as shown in Table 9, the film thickness of the carrier injection blocking layer 5 and the film thickness of the a-Si based photoconductive layer 6 are changed. A variety of photoconductors E and F were manufactured. This film thickness was formed on a separately prepared conductive substrate under the same conditions, and the step between the adhesion region and the non-adhesion region of the film was measured by a surface roughness meter, and was determined based on these conditions and calculations.

[0049]

[Table 8]

[0050]

[Table 9]

With respect to the two types of the photoconductors E and F thus obtained, the photoconductor temperature was set at 45 ° C., and 10,000 sheets were printed at room temperature and normal humidity (33 ° C., 85% RH). After this 10,000-sheet printing endurance was repeated 10 times, under high temperature and high humidity (33 ° C,
After leaving it at 85% RH for 12 hours and turning on the power in this state to see the state of the initial image, the results shown in Table 10 were obtained for image fogging, image deletion, and the presence or absence of black spots. Was given. The developing potential of the printer used for this evaluation is 450V.

[0052]

[Table 10]

As is clear from this result, the film thicknesses of the carrier injection blocking layer 5 and the a-Si photoconductive layer 6 are as follows (a) with respect to the development potential given by the equipment and recording method.
It was found that in the case of (b), that is, in the case of the photoconductor E, there was no image fogging and image deletion, and an excellent photoconductor in which the generation of black spots was improved was obtained. (A) Thickness of carrier injection blocking layer (μm)> 0.003
0 × development potential (V) (b) film thickness (μm) of a-Si-based photoconductive layer> 0.050
× Development potential (V) (Example 4) In this example, as shown in Table 11, the conductive substrate 4 made of aluminum (the substrate 4 has a drum shape,
The outer diameter is Φ30 mm, the inner diameter is Φ25 mm, and the longitudinal dimension is 260 mm).
System photoconductor E is manufactured, and thus photoconductor G to photoconductor I are produced.
Was produced.

[0054]

[Table 11]

With respect to the thus obtained three types of photoconductors G to I, the cleaning level of the image deletion prevention cleaning process is deteriorated and the image deletion is liable to occur, whereby the image after the drum heater is turned on is set. When the flow recovery time was measured, the results shown in Table 11 were obtained. When the amount of deformation of each substrate 4 was measured by this production, the results shown in the same table were obtained.

As is clear from the results shown in Table 11, the degree of recovery of image deletion is good as the thickness of the substrate is small, but on the other hand, the deformation of the substrate progresses.

According to the experiments repeated by the present inventor,
The substrate 4 has a drum shape and the outer diameter is Φ10.
If the inner diameter is 300 mm, the inner diameter is Φ8.6 to 288 mm, and the longitudinal dimension is 50 to 1,000 mm, the thickness of the substrate is 0.7 to 6.0 mm, preferably 1.0 to 4.0 mm. did.

[0058]

As described above, according to the present invention, the carrier injection blocking layer is set to have a relatively rough film structure by setting the atomic density of the amorphous state to 5.5 × 10 ²² atoms / cm ³ or less. Further, the water content of both layers was reduced by setting the atomic density of the photosensitive layer in the amorphous state to 5.0 × 10 ²² atoms / cm ³ or less to form a relatively rough film structure. If the density of dangling bond compensating atoms in both layers is set to 2.0 × 10 ²¹ atoms / cm ³ or more,
In a rough film structure, atoms with a small covalent radius are evenly distributed so as to fill the gaps, and also have a water-repellent action that repels water, which can reduce the amount of water that tends to adsorb and enter. It was Furthermore, if both the carrier injection blocking layer and the photosensitive layer contain oxygen or a mixed atom of nitrogen or carbon containing at least oxygen of 5.0 × 10 ²¹ atoms / cm ³ or less, a hygroscopic silicon oxide-based material is obtained. S
The iO (N: C) compound was reduced, and the water content was reduced even when the compound was placed under high temperature and high humidity. Moreover, the surface layer contains at least one atom of Si or Ge in an amorphous state contained at 3.0 × 10 ²² atoms / cm ³ or less and 5.0 × 10 ²² atoms / cm ³ or less. By combining at least one atom of N or C in an amorphous state, a surface layer having a relatively rough film structure was laminated, and the water content of the surface layer was reduced. As a result, even when the printing test was repeated under high temperature and high humidity, the surface potential did not decrease, image fog and image deletion did not occur, and the occurrence of black spots was improved. A high quality and highly reliable electrophotographic photosensitive member can be provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a layer structure of an electrophotographic photosensitive member according to an example.

FIG. 2 is a schematic explanatory diagram of a glow discharge decomposition apparatus used in an example.

FIG. 3 is a cross-sectional view showing the basic structure of an amorphous silicon-based electrophotographic photosensitive member.

[Explanation of reference numerals] 1, 4 ... Conductive substrate 5 ... Carrier injection blocking layer 2, 6 ... Amorphous silicon-based photoconductive layer 3, 7 ... Surface layer

Claims (1)

[Claims] 1. Silicon, germanium, on a conductive substrate,
A carrier injection blocking layer composed of an atom in an amorphous state composed of at least one of oxygen, nitrogen and carbon and a hydrogen atom or a fluorine atom compensating for a dangling bond of the atom, and a photosensitive layer are sequentially laminated, and An electrophotographic photoreceptor having thereon a surface layer comprising an atom in an amorphous state composed of at least one of silicon, germanium, nitrogen and carbon and an atom of hydrogen or fluorine compensating for a dangling bond of the atom, The atomic density of the carrier injection blocking layer in the amorphous state is 5.5 × 10 ²² atoms /
1. The atomic density of at least one of hydrogen and fluorine, which is less than or equal to ³ cm ³ and compensates for dangling bonds, is 2.
0 × 10 ²¹ atoms / cm ³ or more, and the atomic density of the photosensitive layer in the amorphous state is 5.0 × 10 ²² atoms / cm ³
And the density of at least one atom of hydrogen or fluorine that is less than or equal to and compensates for dangling bonds is 2.0 ×
10 ²¹ atoms / cm ³ or more, and at least one of amorphous silicon or germanium in the surface layer.
The density of the atoms of the seed is 3.0 × 10 ²² atoms / cm ³ or less and the density of at least one atom of nitrogen or carbon in an amorphous state is 5.0 × 10 ²² atoms / cm.
The density of at least one atom of hydrogen or fluorine that is ³ or less and compensates for dangling bonds is 5.0.
× 10 ²² atoms / cm ³ or more, an electrophotographic photoreceptor.