JP2913066B2 - Electrophotographic photoreceptor - Google Patents

Description

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

[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 formation of an electrostatic latent image on a photoreceptor and the transfer of the electrostatic latent image to recording paper are performed in separate steps. 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.

In response to the demand for miniaturization and low power consumption using an optical print head consisting of an LED array and EL array, which has been rapidly developing in recent years, the sensitivity of the photoconductor is insufficient and it cannot be satisfied. Was.

In addition, since the photoconductor does not come in contact with a developing device or a cleaner, the TESI process eliminates abrasion and scratching of the photoconductor surface as compared with the normal Carlson method, and can extend the life of the photoconductor. On the other hand, the conventional photoconductive material has a problem that the surface hardness is not high, so that the surface of the photoreceptor is worn out or scratched due to the contact with the electrostatic recording paper or the transfer roller. is there.

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 achieves high sensitivity to light in the visible light region and achieves a long life. An object of the present invention is to provide a suitable electrophotographic photosensitive member.

[Means for solving the problem]

In the present invention, the surface of the photoreceptor having the translucent support is brought into contact with one main surface of the dielectric, and at the same time as the image exposure from the side of the translucent support, the other main surface of the dielectric and the photoreceptor The present invention relates to an electrophotographic photoreceptor used in a simultaneous electrostatic latent image transfer method for applying a voltage, wherein the translucent support includes a translucent electrode, and a Group IIIa element of the periodic table is provided on the support. 1 to 10,000 ppm or 5,000 ppm of Group Va element
An amorphous silicon-based carrier injection blocking layer and an amorphous silicon-based photoconductive layer are sequentially laminated (hereinafter, amorphous silicon is abbreviated as a-Si).
Inclusion of carbon, oxygen and nitrogen in the Si injection blocking layer
The band gap is made larger than that of the Si photoconductive layer, and the LED head is applied to the image exposure.

 Next, the present invention will be described in detail.

FIG. 1 shows a typical layer constitution of the electrophotographic photoreceptor of the present invention.

In FIG. 1, reference numeral 1 denotes a light-transmitting support, on which a light-transmitting electrode layer 2, an a-Si-based carrier injection blocking layer 3, and an a-Si-based photoconductive layer 4 are sequentially laminated. .

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, or transparent organic resins such as fluorine resin, 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 by evaporation or sputtering. , Au or the like may be formed as thin as to be translucent.

The a-Si-based carrier injection blocking layer 3 and the a-Si-based photoconductive layer 4 are formed by glow discharge decomposition, sputtering, ECR,
A film is formed by an evaporation method or the like, and an element for terminating a dangling bond, for example, hydrogen (H) or halogen is contained in the formation.

The a-Si based carrier injection blocking block 3 needs to have a band gap larger than that of the photoconductive layer 4 so that the layer itself does not absorb light effective for photocarrier generation in the photoconductive layer. May contain an element such as carbon, oxygen, or nitrogen. Then, by containing these elements, the adhesion to the electrode layer 2 is enhanced.

Further, the carrier injection blocking layer 3 contains an impurity element for preventing carrier injection from the electrode layer 2 into the photoconductive layer 4.

That is, in order to prevent the injection of negative charge carriers, the Group IIIa element of the Periodic Table is 1 to 10,000 ppm, preferably 100 to 50,000.
On the other hand, in order to prevent the injection of positive charge carriers, the Group Va element should be contained in an amount of 5,000 ppm or less, preferably 300 to 3,000 ppm. These elements may be provided with a gradient in the layer thickness direction, in which case the average content of the entire layer may be within the above range.

When the carrier injection blocking layer 3 contains a Group IIIa element as described above, the latent image finally transferred to the dielectric becomes a negative charge, whereas when the carrier injection blocking layer 3 contains a Group Va element, the latent image finally becomes negative. The latent image transferred to the dielectric has a positive charge.

As a group IIIa element, element B is preferable because it has excellent covalent bonding properties and can change semiconductor characteristics sensitively, and furthermore, excellent injection stopping power and photosensitivity can be obtained.

As a group Va element, the P element is preferable because it has excellent covalent bonding properties and can change semiconductor characteristics sensitively, and furthermore, excellent injection stopping power and photosensitivity can be obtained.

The thickness of the carrier injection blocking layer 3 is 0.1 to 10 μm.
m, preferably in the range of 0.3 to 5 μm, whereby it is easy to secure the withstand voltage required for forming an electrostatic latent image, and it is also possible to suppress unnecessary absorption of light exposure in this layer to achieve photoconductivity. Photocarriers can be effectively generated in the layer, and the rise in residual potential can be suppressed.

In the a-Si-based photoconductive layer 4, a part of the silicon element is replaced with an element such as carbon, oxygen, nitrogen, germanium, tin, and sulfur to appropriately change physical properties such as conductivity, band gap, and surface hardness. Is also good. When an LED head is used as a light source, the light is effectively received by the a-Si-based layer.However, when an EL head is used, the emission wavelength is shifted to a shorter wavelength side. Carbon, oxygen,
It is preferable to increase the band gap by containing an element such as nitrogen. In the case where a semiconductor laser is used, the emission wavelength is shifted to a longer wavelength. Therefore, the band gap may be narrowed by including an element such as germanium or tin in the a-Si layer.

Furthermore, 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 4.

The thickness of the a-Si-based photoconductive layer 4 is preferably in the range of 0.1 to 100 μm, preferably 1 to 50 μm, whereby the dielectric strength required for forming an electrostatic latent image is easily ensured, and It is possible to effectively generate photocarriers by absorption, and to suppress an increase in residual potential.

Thus, when the electrophotographic photosensitive member 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 can be reduced due to the high light sensitivity. LED head and E that were not used in the body
A small and low power consumption exposure light source such as an L head 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, the formation of the a-Si based carrier injection blocking layer 3 increases the dielectric strength of the photoreceptor and suppresses the transfer of background charge. As a result, a good image with high contrast and no back fogging can be obtained. .

In the above electrophotographic photoreceptor, the translucent electrode layer 2 is laminated on the support 1 for translucency, but other translucent supports 1 are formed using a conductive material. It may have an electrode function, and the electrode layer 2 may not be necessary.

〔Example〕

 Next, examples of the present invention will be described.

(Configuration of Electrophotographic Copying Machine) FIG. 2 shows a configuration of the electrophotographic copying machine used in this embodiment.

In FIG. 1, an LED head 6 and an erase head are provided inside a photosensitive drum 5 in which a light-transmitting electrode layer 2, a carrier injection blocking layer 3 and a photoconductive layer 4 are sequentially laminated on a drum-shaped light-transmitting support 1. The lamp 7 is arranged. A voltage can be applied to the translucent electrode layer 2 by the DC power supply 8. Reference numeral 9 denotes a conductive roller, 10 denotes a developing device, and 11 denotes a fixing device. An electrostatic transfer paper 12 is transported between the photoconductor 5 and the conductive roller 9.

In such a configuration, when a voltage is first applied between the translucent electrode layer 2 of the photosensitive drum 5 and the conductive roller 9 via the electrostatic transfer paper 12 and image exposure is performed by the LED head 6, light A charge latent image corresponding to the 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 12 is separated from the photoconductor drum 5 as the photoconductor drum 5 rotates. At this time, the charge latent image is transferred onto the electrostatic transfer paper 12 by air discharge in a gap between the two. The electrostatic latent image is subsequently developed as a toner image by the developing device 10 and fixed by the fixing device 11. On the other hand, the photoreceptor drum 5 is erased of residual charges by irradiation with light from the erase lamp 7 and is used for forming a next latent image.

(Example 1) As a transparent electrode layer on the peripheral surface of a transparent cylindrical glass substrate
An ITO layer was formed to a thickness of 1000 mm by an electron beam evaporation method, and then a carrier injection blocking layer and a photoconductive layer were sequentially stacked thereon using a capacitively coupled glow discharge decomposition apparatus under the film forming conditions shown in Table 1. .

The photoreceptor thus obtained was mounted on the electrophotographic copying machine shown in FIG.
nm, 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) Similar to (Example 1), on the peripheral surface of a transparent cylindrical glass substrate
An ITO layer was formed to a thickness of 1000 mm by an electron beam evaporation method.

Then, a photoconductive fine powder CdS · nCdCO 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.

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 1.0 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 a carrier was injected using a capacitively coupled glow discharge decomposition apparatus under the film forming conditions shown in Table 2. A blocking layer and a photoconductive layer were sequentially laminated.

The photoreceptor thus obtained is mounted on an electrophotographic copying machine,
An LED head is placed inside the photoreceptor and the wavelength is 660 nm,
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. After evaluating this image,
As in (Example 1), the image had an image density of OD of 1.0, no fogging of the background, and a good resolution.

In this image evaluation test, the LED head as the exposure light source was changed to an EL head with a wavelength of 585 nm, and the exposure amount was 0.9 μJ / cm ^2.
When an image was similarly obtained while performing image exposure under the conditions described above, a similarly good image was obtained, and it was confirmed that the a-Si photoconductive layer exhibited higher sensitivity characteristics to light having a shorter wavelength than the a-Si photoconductive layer. .

(Example 4) in fabricating the same photoconductor (Example 1), B ₂ H ₆ by changing the gas flow rate changing B element content, the 10 kinds of the photoreceptor A~J shown in Table 3 Produced. Then, the image density and the back fog when each photoconductor was used were evaluated.

In the table, ◎ indicates the case where the most excellent result was obtained, 〇 indicates the case where a somewhat excellent result was obtained, and △ indicates the case where a slightly inferior result was obtained.

From the above results, it is understood that the photoconductors B to I obtained excellent results in image density and back fog. In addition, the resolving powers of the images on the photoconductors B to I were all good results.

(Example 5) in fabricating the same photoconductor (Example 3), changing the P element content of the first a-SiC layer by changing the PH ₃ gas flow rate of K~T shown in Table 4 Ten types of photoreceptors were produced. Then, the image density and the back fog when each photoconductor was used were evaluated.

From the above results, it can be seen that the photoconductors K to R obtained excellent results in image density and back fog. The resolution of the images on the photoconductors K to R was all good.

〔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 present invention, it is possible to provide an electrophotographic photoconductor for TESI which has high durability and long life because of its excellent surface hardness.

Furthermore, according to the electrophotographic photoreceptor of the present invention, a good image having high contrast and no fog was obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the layer structure of the electrophotographic photoreceptor of the present invention, and FIG. 2 is an explanatory view of the TESI method. DESCRIPTION OF SYMBOLS 1 ... Translucent support 2 ... Translucent electrode layer 3 ... Amorphous silicon-based carrier injection blocking layer 4 ... Amorphous silicon-based photoconductive layer

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Ito 6 1166 Haseno, Snakegrove-cho, Yokaichi-shi, Shiga Pref. In the Shiga Yokaichi Plant of Kyocera Corporation (56) References JP-A-1-296254 (JP, A) JP-A-2-173756 (JP, A) JP-A-2-245766 (JP, A) JP-A-55-157747 (JP, A) (58) Int.Cl. ⁶ , DB name) G03G 5/00-5/16

Claims (1)

(57) [Claims] An element of Group IIIa of the Periodic Table of 1 to 10,000 ppm or an element of Group Va of the Periodic Table of 5,000 ppm on the translucent electrode.
An amorphous silicon carrier injection blocking layer including:
Simultaneous electrostatic latent image transfer method in which voltage is applied to the translucent electrode simultaneously with image exposure from the translucent electrode side by the LED head or EL head to the photoreceptor that is formed by sequentially laminating amorphous silicon photoconductive layers An electrophotographic photoconductor to be applied, wherein the amorphous silicon carrier injection blocking layer contains carbon, oxygen or nitrogen to increase the band gap as compared with the amorphous silicon photoconductive layer.