Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Patent
1988-04-21
1989-12-19
Martin, Roland E.
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
430 59, 430 66, 430 67, G03G 514
Patent
active
048882623
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an electro photographic image forming method and, more particularly, to an image forming method in which a positive charging photoreceptor is employed.
BACKGROUND ART
Hitherto, as a typical electro photographic photoreceptor for image forming purposes, a photoreceptor, for example, of the type having a photoreceptive layer containing inorganic photoconductive materials, such as selenium, zinc oxide, and cadmium sulfide, has been widely used.
Recently, various research and development efforts have been actively made for utilization of various kinds of organic photoconductive materials as materials for a photoreceptive layer of an electro-photographic photoreceptor.
For example, in Japanese Patent Publication No. 10496/1975 there is described an organic photoreceptor having a photoreceptive layer containing poly-N-vinylcarbazole and 2,4,7-trinitro-9-fluorenone. However, this photoreceptor is not very satisfactory in respect of sensitivity and durability. In order to overcome such deficiencies, attempts are being made to develop an organic photoreceptor having a photoreceptive layer in which charge generating and change transporting functions are separately pereformed by different materials, whereby high sensitivity and high durability requirements can be met.
In such electro-photographic photoreceptor of the so-called function partition type, materials capable of individually pereforming different functions can be selected from a wide range of groups of materials, and therefore an electrophotographic photoreceptor having any desired characteristics can be fabricated comparatively easily.
A large number of materials have hitherto been proposed as charge generating materials effective for use in such function partition type photoreceptor. For use of an inorganic material as such, in Japanese Patent Publication No. 16198/1968, for example, there is described the use of amorphous selenium, which material is used in combination with an organic charge transporting material.
Varieties of electro-photographic photoreceptors in which organic dyes or organic pigments are used as charge generating materials have also been proposed; for example, those having a photoreceptive layer containing a bisazo compound are already known through Japanese Provisional Patent Publication Nos. 37543/1972, 22834/1980, 79632/1979, and 116040/1981.
Now, the prior-art photoreceptors using aforesaid organic photoconductive materials are generally used as such for negative charging. The reason for this is that greater Hall mobility of charge is available in the case of negative charging, which fact is advantageous in respect of photosensitivity and otherwise. However, it has been found that the use of such negative charging photoreceptor involves the following problems.
One problem is that ozone is likely to be generated in the atmosphere in the course of negative charging by an electrifier, which will affect the environmental conditions. Another problem is that the development of a negative charging photoreceptor requires positive polarity toners, which are difficult to manufacture in view of the sequence of their triboelectric effect in relation to charge particles of ferromagnetic substances.
In view of these problems, it has been proposed to employ a photoreceptor using organic photoconductive materials, as such for positive charging. For example, when a charge transport layer is laid on a charge generating layer in forming a photoreceptor, the use of a material having a large electron transfer capability, such as trinitrofluorenone, for the charge transport layer has been proposed in order to efficiently nullify the positive charge on the surface of the photoreceptor. However, the use of such material is very unsuitable from the standpoint of pollution control, because the material is carcinogenic.
Another type of positive charging photoreceptor is disclosed in the specification of U.S. Pat. No. 3,615,414, which is such that thiapyrilium salt (a charge generating material) is used in
REFERENCES:
patent: 4563408 (1986-01-01), Lin et al.
patent: 4599286 (1986-07-01), Limburg et al.
patent: 4741981 (1988-05-01), Hashimoto et al.
Etoh Yoshihiko
Kudoh Koichi
Takei Yoshiaki
Tamaki Kiyoshi
Bierman Jordan B.
Konica Corporation
Martin Roland E.
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