JP2920663B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member suitable for a simultaneous electrostatic latent image transfer system for simultaneously forming an electrostatic latent image and transferring an electrostatic latent image.

[Conventional technology]

As an electrophotographic method, an electrostatic latent image transfer method in which an electrostatic latent image on a photoreceptor is temporarily transferred to a recording paper provided with a dielectric layer and the electrostatic latent image is developed with toner is already known. This electrophotography is based on Transfer of Electro-Static Image.
Method, the so-called TESI method, which is roughly classified into a "sequential transfer method" in which the electrostatic latent image format on the photoconductor and the transfer of the electrostatic latent image to recording paper are performed in separate steps, and a photoconductor and recording paper There is a "simultaneous transfer method" in which image exposure is performed in a state where the electrostatic latent images are stacked, and an electrostatic latent image is simultaneously formed and transferred to form an electrostatic latent image on recording paper.

The photoreceptor used in the latter simultaneous transfer method has a basic structure in which a photoconductive layer is laminated on a light-transmitting conductive support, and the conductive support and the photoconductive layer are combined with each other to further improve the contrast. A layer configuration in which an insulating layer is formed between the layers has been proposed (see Japanese Patent Publication No. 57-55140 and Japanese Patent Application Laid-Open No. 56-43665).

In addition, JP-A-49-52643 discloses a layer structure in which an organic photoconductive layer having a higher dark resistance than the photoconductive layer is formed between the conductive support and the photoconductive layer. No. 46067 also proposes a layer configuration in which a transparent electrode layer, a photoconductive injection blocking layer and a photoconductive layer are sequentially laminated on a transparent support.

[Problems to be solved by the invention]

Se, Se-Te, Se-As, Te-As, ZnO, ZnCd
Inorganic materials such as S, CdS, CdS.nCdCO ₃ , CdSe, CdTe, PbO, and Sb ₂ S ₃ and organic materials such as polyvinylcarbazole, anthracene, and anthraquinone have been used.

However, these photoconductive materials do not have sufficiently high photosensitivity, and thus require a large exposure energy (tens to hundreds of lux seconds) when forming an electrostatic latent image.

Therefore, when an optical print head composed of an LED array or an EL array, which has been rapidly developed in recent years, is used, the size of the copying apparatus can be reduced. Was insufficient and I was not satisfied.

In addition, since the photoconductor does not come in contact with a developing device or a cleaner, the TESI method has less wear and scratches on the surface of the photoconductor than the ordinary Carlson method, and can extend the life of the photoconductor. On the other hand, with conventional photoconductive materials,
There is a problem that the surface hardness is not high, so that the surface of the photoreceptor is worn or scratched due to contact with the electrostatic recording paper or the transfer roller.

Accordingly, the present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a simultaneous electrostatic latent image transfer method that can be obtained with high sensitivity to light in the visible light region and that has a long life. An object of the present invention is to provide a suitable electrophotographic photosensitive member.

[Means for solving the problem]

The present invention relates to a photoconductor in which a light-transmitting insulating layer and an amorphous silicon photoconductive layer are sequentially laminated on a light-transmitting electrode.
An electrophotographic photoreceptor applied to a simultaneous electrostatic latent image transfer method in which a voltage is applied to the translucent electrode simultaneously with image exposure from the translucent electrode side by an LED head or an EL head, wherein the translucent insulating layer Is composed of an amorphous silicon-based light-transmitting insulating layer having a band gap of 1.9 eV or more and a resistivity of 10 ¹³ Ωcm or more containing carbon, oxygen or nitrogen, and carbon, oxygen and nitrogen are formed on the amorphous silicon photoconductive layer. Or containing germanium and having the composition formula Si _1-X A _x (A: C,
(N, O, Ge) to cover an amorphous silicon-based surface layer defined as 0.5 ≦ x ≦ 0.95 (amorphous silicon is abbreviated as a-Si).

 Next, the present invention will be described in detail.

FIG. 1 and FIG. 2 are views showing typical layer constitutions of the electrophotographic photoreceptor of the present invention.

In these figures, reference numeral 1 denotes a light-transmitting support, on which a light-transmitting electrode layer 2 and an a-Si based photoconductive layer 3 are sequentially laminated, or an a-Si They are laminated via an intermediate layer 4 as a system light-transmitting insulating layer. Then, a surface layer 5 as an a-Si based insulating layer is formed on the photoconductive layer 3.

The translucent support 1 has a shape such as a plate shape, a drum shape, a sheet shape, and a belt shape.
There are transparent inorganic materials such as sapphire, transparent organic resins such as fluororesin, polyester, polycarbonate, polyethylene, polyethylene terephthalate, vinylon, epoxy and mylar, as well as optical fibers and selfoc optical plates.

The transparent electrode layer 2 is made of a transparent conductive material such as ITO (indium tin oxide), tin oxide, lead oxide, indium oxide, copper iodide, or Al, Ni, Au by vapor sputtering. Or the like may be formed thin enough to be translucent.

The a-Si-based photoconductive layer 3, the intermediate layer 4, or the surface layer 5 is formed by a glow discharge decomposition method, a sputtering method, an ECR method, a vapor deposition method, or the like. Contains hydrogen (H) and halogen.

In the a-Si-based photoconductive layer 3, even if a part of the silicon element is replaced with an element such as carbon, oxygen, nitrogen, germanium, tin, and sulfur, physical properties such as conductivity, band gap, and hardness are appropriately changed. Good. When an LED head is used as a light source, light is effectively received by the a-Si-based layer.
When a head is used, the emission wavelength shifts to the shorter wavelength side. Therefore, it is preferable to increase the band gap by including an element such as carbon, oxygen, or nitrogen in the a-Si layer.
When a semiconductor laser is used, its emission wavelength shifts to a longer wavelength side. Therefore, the band gap may be narrowed by containing an element such as germanium or tin in the a-Si layer.

Further, the electrical characteristics can be adjusted by adding a group IIIa element or a group Va element of the periodic table to the a-Si-based photoconductive layer 3.

The thickness of the a-Si-based photoconductive layer 3 is preferably in the range of 0.1 to 100 μm, and more preferably 1 to 50 μm, so that the dielectric strength required for forming an electrostatic latent image can be easily secured. To effectively generate photocarriers, and furthermore, it is possible to suppress an increase in residual potential.

The intermediate layer 4 needs to have a band gap larger than that of the photoconductive layer 3 so that the layer itself does not absorb light effective for generating photocarriers in the photoconductive layer 3. An optical energy gap (hereinafter abbreviated as Egopt) containing an element such as nitrogen is preferably set to 1.9 eV or more. Further, in order to effectively prevent the injection of carriers from the electrode layer 2 into the photoconductive layer 3, the resistivity is desirably set to 10 ¹³ Ωcm or more.

The thickness of the intermediate layer 4 is 0.1 to 10 μm, preferably 0.3 to 5 μm.
The range of μm is preferable, whereby it is easy to secure the dielectric strength required for forming the electrostatic latent image. In addition, absorption of exposure in the intermediate layer is suppressed, and photocarriers are effectively used in the photoconductive layer 3. It can be generated, and the rise of the residual potential can be suppressed.

For the surface layer 5, elements such as carbon, nitrogen, and oxygen are contained in the a-Si layer in order to increase hardness and provide insulation. Further, a germanium element may be contained in order to increase the moisture resistance. These contained elements are indicated as A, and the content ratio is a-Si _1-x (A: C, N, O, G
In the case indicated by e), 0.3 ≦ x ≦ 1.0, preferably, 0.5 ≦ x ≦ 0.95.

The thickness of the surface layer 5 is 0.05 to 5 μm, preferably 0.1 to 5 μm.
The range is preferably 3 μm, and within this range, the dielectric strength and surface hardness of the photoreceptor can be increased, the environmental resistance such as moisture resistance can be increased, and the rise in residual potential can be suppressed.

Thus, when the electrophotographic photoreceptor having the above configuration is used in the simultaneous electrostatic latent image transfer method, the exposure energy at the time of forming the electrostatic latent image is reduced due to high light sensitivity. A small and low power consumption exposure light source such as an LED head or an EL head that could not be used can be used.

Also, the surface hardness is higher than that of the conventional photoreceptor, so that a long-life electrophotographic photoreceptor can be provided. The Vickers hardness of the amorphous As ₂ Se ₃ layer is 150k
a g / mm ^2, although an organic photoconductive layer is less hardness, the Vickers hardness of the hand a-Si layer 1500-20
00 kg / mm ² , and when carbon, oxygen and nitrogen are added thereto, the hardness becomes higher.

Further, when the intermediate layer 4 and the surface layer 5 are formed, the withstand voltage of the photoreceptor can be increased, and the transfer of background charge can be suppressed. As a result, a good image with high contrast and no fogging of the back can be obtained.

In the above electrophotographic photoreceptor, the translucent support 1
Although the light-transmitting electrode layer 2 is laminated thereon, the light-transmitting support 1 may be formed by using a conductive material and provided with an electrode function, so that the electrode layer 2 is not required.

〔Example〕

 Next, examples of the present invention will be described.

(Configuration of Electrophotographic Copying Machine) FIG. 3 shows a configuration of the electrophotographic copying machine used in this embodiment.

In FIG. 1, an LED head 7 and an erase lamp 8 are provided inside a photosensitive drum 6 in which a light-transmitting electrode layer 2, a photoconductive layer 3 and a surface layer 5 are sequentially laminated on a drum-shaped light-transmitting support 1. Place. A voltage can be applied to the translucent electrode layer 2 by the DC power supply 9. 10 is a conductive roller, 11
Denotes a developing device, and 12 denotes a fixing device.
During this time, the electrostatic transfer paper 13 is transported.

In such a configuration, when a voltage is first applied between the translucent electrode layer 2 of the photosensitive drum 6 and the conductive roller 10 via the electrostatic transfer paper 13 and image exposure is performed by the LED head 7, light A charge latent image corresponding to image exposure is formed on the surface of the photoconductor by photocarrier generation and photocarrier transport in the conductive layer 3, and then, the electrostatic transfer paper 13 is brought into contact with the photoconductor drum 6 with the rotation of the photoconductor drum 6. At the time of peeling, a charge latent image is transferred onto the electrostatic transfer paper 13 by air discharge in a gap between the two. The electrostatic latent image is subsequently developed as a toner image by the developing device 11 and fixed by the fixing device 12. On the other hand, the photoreceptor drum 6 is thereafter erased from the residual charges by light irradiation of the erase lamp 8, and is used for forming the next latent image.

(Example 1) An ITO layer is formed on the peripheral surface of a transparent cylindrical glass substrate as the light-transmitting electrode layer 2 to a thickness of 1000 mm by an electron beam evaporation method, and then a capacitively coupled glow discharge decomposition apparatus is used thereon. The a-Si based photoconductive layer was laminated under the film forming conditions shown in Table 1.

The photoreceptor thus obtained was mounted on the electrophotographic copying machine shown in FIG. 3, and an LED head was arranged inside the photoreceptor.
m, while the image exposure under the conditions of exposure 1.0μJ / cm ^2,
+ 500V between photoreceptor and electrostatic transfer paper via conductive roller
Was applied. Then, an electrostatic latent image is formed on the electrostatic transfer paper, and subsequently, the electrostatic latent image is developed using a two-component developing machine for negatively charged toner, and the obtained toner image is thermally fixed. An image corresponding to the exposed part was obtained. When this image was evaluated, it was an image having an image density of OD of 1.0, no fogging of the back, and a good resolution.

(Example 2) In producing the electrophotographic photosensitive member of (Example 1), a
-Photoconductive fine powder CdS ・ nCdCO instead of Si-based photoconductive layer
₃ (0.8 ≦ n ≦ 1.0) was dispersed in an acrylic resin together with a metal activator to form a thermosetting photoconductive layer having a thickness of 30 μm, and the other configuration was the same as that of (Example 1).

The photoreceptor thus obtained was mounted on an electrophotographic copying machine in the same manner as in (Example 1), an LED head was arranged inside the photoreceptor, and image exposure was performed under the conditions of a wavelength of 660 nm and an exposure of 10. μJ / cm ^2. While performing, a voltage of -800 V was applied between the photosensitive member and the electrostatic transfer paper via the conductive roller. Then, an electrostatic latent image is formed on the electrostatic transfer paper, and then the electrostatic latent image is developed using a two-component developing machine of positively charged toner, and the obtained toner image is thermally fixed. An image corresponding to the exposed part was obtained. When this image was evaluated, a sufficient electrostatic latent image was not formed due to insufficient photosensitivity of the photoconductive layer, and an image with almost no density was obtained.

(Example 3) An ITO layer was formed on the peripheral surface of a transparent cylindrical glass substrate to a thickness of 1000 mm by an electron beam evaporation method, and then photoconductive using a capacitively coupled glow discharge decomposition apparatus under the film forming conditions shown in Table 2. Layer and amorphous silicon carbide (hereinafter a-
A surface layer made of SiC) was laminated.

The x value of Si _1-x C _x in the surface layer of the photoreceptor thus obtained was 0.7, and the photoreceptor was mounted on an electrophotographic copying machine, and an LED head was arranged inside the photoreceptor to obtain a wavelength of 660 nm.
m, while the image exposure under the conditions of exposure 1.0μJ / cm ^2,
+ 500V between photoreceptor and electrostatic transfer paper via conductive roller
Was applied. Then, an electrostatic latent image is formed on the electrostatic transfer paper, and then the electrostatic latent image is developed using a two-component developing machine of negatively charged toner, and the obtained toner image is thermally fixed and exposed. An image corresponding to the part was obtained. When this image was evaluated, it was an image having an image density of OD of 1.0, no fogging of the back, and a good resolution as in (Example 1).

In this image evaluation test, the exposure amount was 1.2 μJ / cm ²
When an image was similarly obtained by applying a voltage of +700 V while performing image exposure under the conditions described above, the image had an image density of OD of 1.2, no fogging of the back, and a good resolution.

(Example 4) An ITO layer was formed on the peripheral surface of a transparent cylindrical glass substrate to a thickness of 1000 mm by an electron beam evaporation method, and then a-g under a film forming condition shown in Table 3 using a capacitively coupled glow discharge decomposition apparatus. Si
A system photoconductive layer and a surface layer were laminated.

The x value of Si _1-x N _x in the surface layer of the photoreceptor thus obtained was 0.60, the photoreceptor was mounted on an electrophotographic copying machine, an LED head was arranged inside the photoreceptor, and a wavelength of 660 nm was exposed. amount
While performing image exposure under the condition of 1.0 μJ / cm ^2, a voltage of +500 V was applied between the photosensitive member and the electrostatic transfer paper through the conductive roller to form an electrostatic latent image on the electrostatic transfer paper. . And
Subsequently, the electrostatic latent image was developed using a two-component developing machine for negatively charged toner, and the obtained toner image was thermally fixed to obtain an image corresponding to an exposed portion. After evaluating this image,
OD has an image density of 1.0, no fogging of the back,
The image had a good resolving power.

Next, while performing image exposure under the condition of an exposure amount of 1.2 μJ / cm ² , a voltage of +700 V is applied to form an electrostatic latent image on the electrostatic transfer paper. The image was developed using a two-component developing machine, and the obtained toner image was thermally fixed to obtain an image corresponding to the exposed portion. When this image was evaluated, it was an image having an image density of OD of 1.2, no fogging of the back, and a good resolution.

On the other hand, for the photoconductor of (Example 1), the exposure amount was 1.2
While performing image exposure under the condition of μJ / cm ² , a voltage of +700 V is applied to form an electrostatic latent image on the electrostatic transfer paper, and then the electrostatic latent image is developed in a two-component system using negatively charged toner. The toner image was heat-fixed to obtain an image corresponding to the exposed portion. When this image was evaluated, spot-like noise due to dielectric breakdown of the photoreceptor was observed over almost the entire surface, and the resolution was poor.

(Example 5) An ITO layer was formed on the peripheral surface of a transparent cylindrical glass substrate to a thickness of 1000 mm by an electron beam evaporation method, and then an intermediate layer was formed using a capacitively coupled glow discharge decomposition apparatus under the film forming conditions shown in Table 4. , A photoconductive layer and a surface layer.

The x value of Si _1-x N _x in the surface layer of the photoreceptor thus obtained was 0.7, the photoreceptor was mounted on an electrophotographic copying machine, and an LED head was arranged inside the photoreceptor, and a wavelength of 660 nm was exposed. amount
While performing image exposure under the condition of 1.0 μJ / cm ^2, a voltage of +500 V was applied between the photosensitive member and the electrostatic transfer paper through the conductive roller to form an electrostatic latent image on the electrostatic transfer paper. . And
Subsequently, the electrostatic latent image was developed using a two-component developing machine for negatively charged toner, and the obtained toner image was thermally fixed to obtain an image corresponding to an exposed portion. After evaluating this image,
OD has an image density of 1.0, no fogging of the back,
The image had a good resolving power.

Next, while performing image exposure under the condition of an exposure amount of 1.2 μJ / cm ² , a voltage of +800 V is applied to form an electrostatic latent image on the electrostatic transfer paper. The image was developed using a two-component developing machine, and the obtained toner image was thermally fixed to obtain an image corresponding to the exposed portion. When this image was evaluated, it was an image having an image density of OD of 1.3, no fogging of the back, and good resolving power.

(Example 6) In this example, in producing the photoreceptor of (Example 5), the photoconductive layer and the intermediate layer were formed under the film forming conditions shown in Table 4, and the surface layer was not formed. Was prepared in the same manner as in (Example 5).

The photoreceptor thus obtained was mounted on the electrophotographic copying machine shown in FIG. 3, and an LED head was arranged inside the photoreceptor.
m, while the image exposure under the conditions of exposure 1.0μJ / cm ^2,
+ 500V between photoreceptor and electrostatic transfer paper via conductive roller
Was applied. Then, an electrostatic latent image is formed on the electrostatic transfer paper, and subsequently, the electrostatic latent image is developed using a two-component developing machine for negatively charged toner, and the obtained toner image is thermally fixed. An image corresponding to the exposed part was obtained. When this image was evaluated, it was an image having an image density of OD of 1.0, no fogging of the back, and a good resolution.

Next, while performing image exposure under the condition of an exposure amount of 1.2 μJ / cm ² , a voltage of +800 V is applied to form an electrostatic latent image on the electrostatic transfer paper. The image was developed using a two-component developing machine, and the obtained toner image was thermally fixed to obtain an image corresponding to the exposed portion. When this image was evaluated, spot-like noise due to dielectric breakdown of the photoreceptor was observed in a part of the image, and the resolution was poor.

(Example 7) An ITO layer was formed on the peripheral surface of a transparent cylindrical glass substrate to a thickness of 1000 mm by an electron beam evaporation method, and then an intermediate layer was formed using a capacitively coupled glow discharge decomposition apparatus under the film forming conditions shown in Table 5. , A photoconductive layer and a surface layer.

The x value of Si _1-x N _x in the surface layer of the photoreceptor thus obtained was 0.6, and the photoreceptor was mounted on an electrophotographic copying machine, and an LED head was arranged inside the photoreceptor, and a wavelength of 660 nm was exposed. amount
While performing image exposure under the condition of 1.0 μJ / cm ² , a voltage of −500 V was applied between the photosensitive member and the electrostatic transfer paper via the conductive roller. Then, an electrostatic latent image is formed on the electrostatic transfer paper, and then the electrostatic latent image is developed using a two-component developing machine of positively charged toner, and the obtained toner image is thermally fixed and exposed. An image corresponding to the part was obtained. When I evaluated this image, O.
D. had an image density of 1.0, no fogging of the background, and a good resolution.

Next, while performing image exposure under the condition of an exposure amount of 1.2 μJ / cm ² , a voltage of −800 V is applied to form an electrostatic latent image on the electrostatic transfer paper. And the resulting toner image was heat-fixed to obtain an image corresponding to the exposed portion. When this image was evaluated, it was an image having an image density of OD of 1.3, no fogging of the back, and good resolving power.

Further, in the image evaluation test, changing the LED head of the exposure light source EL head wavelength 585 nm, while the image exposure with a voltage applied to the condition of the exposure amount 0.9μJ / cm ² of -500 V, the same images As a result, the same good image was obtained, and it was confirmed that light having a shorter wavelength than the a-Si based photoconductive layer exhibited high sensitivity characteristics.

(Moisture Resistance Test) Next, each of the photoconductors of (Example 3), (Example 4), (Example 5) and (Example 7) is mounted on an electrophotographic copying machine shown in FIG. 3 under an environment of 30 ° C. and 85% RH. However, when a running copy test of 10,000 sheets was performed, good images were maintained. On the other hand, in each photoconductor having no surface layer (Example 1) (Example 7),
It was observed that the resolving power gradually decreased.

〔The invention's effect〕

As described above, according to the electrophotographic photoreceptor of the present invention, since the a-Si-based photoconductive layer having high photosensitivity is used, the exposure energy at the time of forming an electrostatic latent image is reduced.
A small and low power consumption exposure light source such as a head and an EL head could be used.

Further, according to the electrophotographic photoreceptor of the present invention, by laminating a surface layer having high hardness, a long-life photoreceptor that is more resistant to abrasion and damage can be obtained. While the photoreceptor has been treated as a consumable item, the use of the photoreceptor of the present invention has a life almost equivalent to the life of the electrophotographic apparatus, and as a result, the photoreceptor does not need to be replaced. It is possible to provide a simple electrophotographic apparatus.

Moreover, according to the electrophotographic photoreceptor of the present invention, the dielectric strength of the photoreceptor can be increased by laminating the surface layer, and problems such as dielectric breakdown can be prevented. Further, since the surface layer is insulative, the transfer of the background charge in the non-exposed portion during the formation of the electrostatic latent image can be suppressed, whereby a high-contrast electrostatic latent image can be obtained.

Further, according to the electrophotographic photoreceptor of the present invention, by providing an insulating layer between the translucent electrode layer and the a-Si based photoconductive layer, injection of carriers from the electrode layer to the photoconductive layer can be effectively prevented. Thus, the withstand voltage of the photoconductor can be increased, and the transfer of background charge can be suppressed. As a result, a good image with high contrast and no back fog can be obtained. In addition, since the adhesion to the electrode layer is higher than when the photoconductive layer is formed directly on the electrode layer, problems such as peeling of the photoconductive layer can be avoided.

[Brief description of the drawings]

1 and 2 are cross-sectional views showing the layer structure of the electrophotographic photoreceptor of the present invention, and FIG. 3 is an explanatory view of the TESI method. DESCRIPTION OF SYMBOLS 1 ... Translucent support 2 ... Translucent electrode layer 3 ... Amorphous silicon type photoconductive layer 4 ... Intermediate layer 5 ... Surface layer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI G03G 15/18 G03G 15/00 115 (72) Inventor Hiroshi Ito 1166, Haseno, Jabizo-cho, Yokaichi City, Shiga Prefecture 6 Kyocera Corporation Shiga Yokaichi Plant (56) References JP-A-2-173756 (JP, A) JP-A-2-176765 (JP, A) JP-A-1-296254 (JP, A) JP-A-2-245766 (JP, A A) (58) Field surveyed (Int. Cl. ⁶ , DB name) G03G 5/00-5/16

Claims (1)

(57) [Claims] 1. A photosensitive member comprising a light-transmitting electrode and a light-transmitting insulating layer and an amorphous silicon photoconductive layer sequentially laminated on the light-transmitting electrode.
An electrophotographic photoreceptor applied to a simultaneous electrostatic latent image transfer method in which a voltage is applied to the translucent electrode simultaneously with image exposure from the translucent electrode side by an LED head or an EL head, wherein the translucent insulating layer Is composed of an amorphous silicon-based light-transmitting insulating layer having a band gap of 1.9 eV or more containing resistivity of 10 ¹³ Ωcm or more containing carbon, oxygen or nitrogen, and on the amorphous silicon photoconductive layer, carbon, oxygen, Composition formula Si _1-X A _x containing nitrogen or germanium
An electrophotographic photoreceptor characterized in that (A: C, N, O, Ge) is coated with an amorphous silicon-based surface layer defined as 0.5 ≦ x ≦ 0.95.