The present invention relates to an electrophotographic photoreceptor containing titanyl phthalocyanine in a crystalline state that has a maximum intensity peak of the Bragg angle 2.theta. at 27.2.degree..+-.0.2.degree. crystal planes corresponding to diffraction lines at 9.6.degree..+-.0.2.degree., 11.7.degree..+-.0.2.degree. and 24.2.degree..+-.0.2.degree. in a diffraction spectrum obtained with characteristic X-rays of Cu K.alpha. at a wavelength of 1.541 .ANG., and that also has an aggregated state such that a visible and near infrared absorption spectrum has a maximum absorption in the range of 780-860 nm, said photoreceptor further containing an ethylene copolymer resin and/or a polyamide resin in an intermediate layer provided between a light-sensitive layer and an electroconductive layer or an electroconductive substrate.

BACKGROUND OF THE INVENTION 
The present invention relates to an electrophotographic photoreceptor, in 
particular, one that is suitable for use with printers, copiers, etc. and 
which shows high sensitivity to light from LEDS and Laser Diode. 
Electrophotographic photoreceptors having high sensitivity to visible 
light are used extensively with copiers, printers, etc. 
Most common photoreceptors that are used in these applications are 
inorganic photoreceptors provided with light-sensitive layers that are 
chiefly composed of inorganic photoconductive materials such as selenium, 
zinc oxide and cadmium sulfide. However, such inorganic photoreceptors are 
not completely satisfactory in such characteristics as photosensitivity, 
heat stability, moisture resistance and durability that are required of 
electrophotographic photoreceptors to be used with copiers, printers, etc. 
For instance, selenium will crystallize upon heating or exposure to dirt 
such as sebum, often leading to deterioration of the photoreceptors that 
use it as a photoconductor. Photoreceptors that use cadmium sulfide are 
low in moisture resistance and durability, whereas those using zinc oxide 
are poor in durability. Further, photoreceptors using selenium or cadmium 
sulfide are subject to great restraints during manufacture and handling 
because of the toxicity of these materials. 
With a view to solving these problems with inorganic photoconductive 
materials, attempts have been made to use a variety of organic 
photoconductive materials in the light-sensitive layers of photoreceptors 
and active R&D efforts are being made today along this line. For example, 
Japanese Patent Publication No. 50-10496 describes an organic 
photoreceptor having a light-sensitive layer containing polyvinylcarbazole 
and trinitro-fluorenone. However, even this photoreceptor is not 
completely satisfactory in terms of sensitivity and durability. To 
overcome this problem, an electrophotographic photoreceptor of a 
functionally separated type in which carrier generating and transporting 
capabilities are individually fulfilled by different materials has been 
developed. In this type of photoreceptors, suitable materials can be 
selected from a broad range of choices and hence a photoreceptor having 
desired characteristics can be obtained fairly easily. For these reasons, 
it is anticipated that an organic photoreceptor having high sensitivity 
and durability can be produced using the concept of function separation. 
Various organic dyes and pigments have so far been proposed for use as 
carrier generating materials in functionally separated electrophotographic 
photoreceptors and those which are used commercially include polycyclic 
quinone compounds typified by dibromoanthanthrone, pyrylium compounds, 
eutectic complexes of pyrylium compounds and polycarbonates, squarium 
compounds, phthalocyanine compounds, azo compounds, etc. 
However, many of these carrier generating materials are predominantly 
sensitive to the short or medium wavelength range of visible light and 
they are not suitable for use in photoreceptors on laser printers that 
employ semiconductor lasers as light sources since they do not have the 
necessary sensitivity in the operating wavelength range of 750-850 nm. 
Certain azo compounds are phthalocyanine compounds have been found to have 
predominant sensitivity in a wavelength range longer than 750 nm. These 
compounds are provided with a specific aggregated or crystalline structure 
not only to shift the predominant absorption to the longer wavelength 
range but also to enhance their ability to generate carriers. To design 
these compounds, reviewing the conditions for their production and those 
for fabricating photoreceptors is important. Because of these technical 
complexities, no carrier generating materials have been discovered that 
are satisfactory in all aspects including chargeability, sensitivity and 
resistance to cyclic use and an electrophotographic photoreceptor having 
high performance is yet to be developed. 
In ordinary electrophotographic photoreceptors, the electrical contact 
between a grounded conductive layer and a light-sensitive layer is not 
microscopically uniform and the efficiency of carrier injection from the 
conductive layer may differ from one site to another, creating local 
differences in the distribution of electric charges held on the 
photoreceptor's surface. These differences will become visible as image 
defects after development, which are white spots in the black background 
in a positive-working development process or black spots in the white 
background in a negative- working reversal development process. In 
particular, black spots appearing in a reversal development process are as 
deleterious to image quality as background fogging. 
With a view to solving these problems, it has been proposed that an 
intermediate layer be provided between a conductive layer and a 
light-sensitive layer so as to block carrier injection into the 
light-sensitive layer. However, as the blocking characteristic increases, 
the sensitivity of the photoreceptor will decrease or the residual 
potential remaining after exposure will increase. Thus, an optimum 
combination of materials for light-sensitive layer and intermediate layer 
has not yet been discovered that is capable of blocking carrier injection 
without suffering the disadvantages described above. 
SUMMARY OF THE INVENTION 
An object, therefore, of the present invention is to provide an 
electrophotographic photoreceptor that has high sensitivity and which yet 
produces low residual potential after exposure. 
Another object of the present invention is to provide an 
electrophotographic photoreceptor that has a satisfactory sensitivity to a 
light source such as Laser Diode that emits light at long wavelengths. 
Still another object of the present invention is to provide an 
electrophotographic photoreceptor that produces few image defects, in 
particular, black spots when processed by reversal development. 
These objects of the present invention can be attained by an 
electrophotographic photoreceptor containing titanyl phthalocyanine in a 
crystalline state that has a maximum intensity peak of the Bragg angle 2 
.theta. at 27.2.degree..+-.0.2.degree. and crystal planes corresponding to 
diffraction lines at 9.6.degree..+-.0.2.degree., 11.7.+-.0.2.degree. and 
24.1.degree..+-.0.2.degree. in a diffraction spectrum obtained with 
characteristic X-rays of Cu Ku at a wavelength of 1.541 .ANG., and that 
also has an aggregated state such that a visible and near infrared 
absorption spectrum has a maximum absorption in the range of 780-860 nm, 
said photoreceptor further containing an ethylene copolymer resin and/or a 
polyamide resin in an intermediate layer provided between a 
light-sensitive layer and an electroconductive layer or an 
electroconductive substrate.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention is described hereinafter in detail. Ethylene 
copolymer resins and polyamide resins in an intermediate layer may be used 
either on their own or as admixtures. Ethylene copolymer resins to be used 
in the present invention are copolymers containing alkylene monomers such 
as ethylene and propylene. Preferred alkylene monomers are echylene. 
Illustrative copolymerizable monomers include vinyl acetate, acrylic acid, 
methacrylic acid, acrylate esters, methacrylate esters, vinyl alcohol, 
vinyl chloride, vinylidene chloride, vinyl fluoride, acrylonitrile, vinyl 
acetal, maleic acid, maleic anhydride, hydroxystyrene, acrylamide and 
vinylpyrrolidone. Preferred comonomers include vinyl acetate, acrylic 
acid, methacrylic acid, maleic acid, acrylate esters and methacrylate 
esters. 
These comonomers preferably occupy 5-50 wt %, more preferably 10-40 wt %, 
of the etylene copolymer. If their content is less than 5 wt %, the 
resulting resin does not have desired properties such as high solubility, 
good adhesion and ease of coating. If the content of comonomers exceeds 50 
wt %, the blocking capability of the resin will decrease markedly. The 
ethylene copolymer desirably has a molecular weight ranging from 2 to 500 
g/10 min in terms of MFR (melt flow rate as measured by the method 
described in JIS K 6730-1981). 
Commercially available resins that can be used as the ethylene copolymer 
resin in the present invention are listed below: 
Sumitate HE-10 (product of Sumitomo Chemical Co., Ltd.), 
Sumitate KA-10, Sumitate KA-20, Sumitate KA-31, 
Sumitate KC-10 and Sumitate KE-10; 
Acrift WH-302 (product of Sumitomo Chemical Co., Ltd.), 
Acrift WK-402 and Acrift WM-506; 
Evaflex A-703 (product of Mitsui Du Pont Polychemical Co., Ltd.) and 
Evaflex A-704; 
New Crel N-010 (product of Mitsui Du Pont Polychemical Co., Ltd.), New Crel 
N-035 and New Crel N-1560; 
Yukaron A-200K (product of Mitsubishi Petrochemical Company Ltd.), Yukaron 
A-2l0M, Yukaron A-2l0S, Yukaron A-220M, Yukaron A-500W, and Yukaron 
A-5l0W; 
Primacol 5980 (product of Dow Chemical Company); NUC-6570 (product of 
Nippon Yunikar Co., Ltd.) and NUC-6070; 
NB-730 (product of Nippon Yunikar Co., Ltd.) and MB-870. 
Typical examples of the polyamide resin that is used in the present 
invention are nylon resins, and copolymer nylons as well as nylon resins 
that have been modified to become soluble in water or alcohols are 
particularly preferred. Examples of such nylon resisns are listed below: 
Lakkamide 5003 (product of Dainippon Ink & Chemicals, Inc.) and Lakkamide 
5216; 
CM 4000 (product of Toray Industries, Ltd.) and CM 8000; 
AQ Nylon A-70 (product of Toray Industries, Ltd.), AQ Nylon A-90 and AQ 
Nylon P-70; 
Tresin F30 (product of Teikoku Kagaku Sangyo K.K.), Tresin MF-30, Tresin 
EF-30T, Tresin M-20, Tresin FS-350 and Tresin FS-500. 
The thickness of the intermediate layer used in the present invention is 
not limited to any particular value but in order to avoid any damage to 
sensitivity characteristics, the intermediate layer is preferably not 
thicker than 10 .mu.m, more preferably not thicker than 4 .mu.m. 
The X-ray diffraction spectrum of the titanyl phthalocyanine to be used in 
the present invention was measured under the following conditions and 
"peaks" in the spectrum are acute-angled projections that are clearly 
distinguishable from noise: 
______________________________________ 
X-ray tube Cu 
Voltage 40.0 kV 
Current 100 mA 
Start angle 6.00 deg. 
Stop angle 35.00 deg. 
Step angle 0.020 deg. 
Time of measurement 0.50 sec. 
______________________________________ 
The absorption spectrum is one of a reflection type which was obtained by 
performing measurement with Model 320 Auto-recording Spectrophotometer of 
Hitachi Ltd. 
The method for preparing the titanyl phthalocyanine that is to be used in 
the present invention is hereunder described by way of example. First, 
titanium tetrachloride is reacted with phthalodinitrile in an inert, 
high-boiling point solvent such as .alpha.-chloronaphthalene. The reaction 
temperature usually ranges from 160.degree. to 300.degree. C., with the 
range of 160.degree.-260.degree. C. being preferred. The resulting 
dichlorotitanium phthalocyanine is hydrolyzed with a base or water to 
obtain titanyl phthalocyanine, which is subsequently treated with a 
solvent to obtain the desired crystal-line form. The treatment with a 
solvent may be performed with a common stirrer but other apparatus can 
also be employed such as a homo-mixer, a disperser, an agitator, a ball 
mill, a sand mill or an attritor. 
The titanyl phthalocyanine described above may be used in combination with 
other carrier generation materials in the present invention. Carrier 
generation materials useful for this purpose are titanyl phthalocyanine 
compounds having different crystalline forms than the titanyl 
phthalocyanine to be used in the present invention, such as u-titanyl 
phthalocyanine,.beta.-titanyl phthalocyanine, titanyl phthalocyanine of 
mixed .alpha.-and .beta.-forms, and amorphous titanyl phthalocyanine. 
Phthalocyanine pigments other than those listed above, azo pigments, 
anthraquinone pigments, perylene pigments, polycyclic quinone pigments, 
squarium pigments, etc. may also be used. 
Various carrier transport materials may be used in the electrophotographic 
photoreceptor of the present invention and representative examples include 
compounds having nitrogenous heterocyclic nuclei or condensed rings 
thereof as typified by oxazole, oxadiazole, thiazole, thiadiazole and 
imidazole, polyarylalkane compounds, pyrazoline compounds, hydrazone 
compounds, triarylamine compounds, styryl compounds, styryltriphenylamine 
compounds, .beta.-phenylstyryl triphenylamine compounds, butadiene 
compounds, hexatriene compounds, carbazole compounds, and condensed 
polycyclic compounds. 
Specific examples of such carrier transport materials are described in 
Unexamined Published Japanese Patent Application No. 61-107356 and the 
structures of typical examples are shown below: 
##STR1## 
Photoreceptors are known to be fabricated in various forms of structure and 
the electrophotographic photoreceptor of the present invention may assume 
any of these forms. Desirably, it is a functionally separated 
photoreceptor of either superposition or dispersion type. Common examples 
of the layer arrangement for a functionally separated photoreceptor is 
shown in FIGS. 1-3. The layer arrangement shown in FIG. 1 comprises a 
conductive support 1 which is coated with an intermediate layer 5, on 
which are superposed a carrier generation layer 2 and a carrier transport 
layer 3 to form a light-sensitive layer 4. In FIG. 2, the arrangement of 
carrier generation layer 2 and carrier transport layer 3 is reversed to 
form a light-sensitive layer 4'. FIG. 3 shows a single-layer arrangement 
in which an intermediate layer 5 is provided on the conductive support 1 
and on this intermediate layer is formed a light-sensitive layer 4" 
containing a carrier generation material 6 and a carrier transport 
material 7 dispersed therein. 
The light-sensitive layer is advantageously formed by coating a carrier 
generation or transport material either on its own or as a solution having 
said material dissolved therein together with a binder or a suitable 
additive. Since carrier generation materials usually have low solubility, 
it is effective to apply a solution having these carrier generation 
materials dispersed as fine particles in suitable dispersion media using a 
dispersing machine such as an ultrasonic disperser, ball mill, sand mill 
or a homo-mixer. In this case, binders and other additives are usually 
added to the resulting dispersion. 
A broad range of solvents or dispersion media may be used to form the 
light-sensitive layer and illustrative examples include: butylamine, 
ethylenediamine, N,N-dimethylformamide, acetone, methyl ethyl ketone, 
cyclohexanone, tetrahydrofuran, dioxane, ethyl acetate, butyl acetate, 
methyl cellosolve, ethyl cellosolve, ethylene glycol dimethyl ether, 
toluene, xylene, acetophenone, chloroform, dichloromethane, 
dichloroethane, trichloroethane, methanol, ethanol, propanol and butanol. 
If a binder is to be used in forming carrier generation or transport layer, 
said binder may be of any type but it is desirable to use a high-molecular 
weight polymer that is hydrophobic and that has a film-forming capability. 
Non-limiting examples of such polymers are listed below: 
______________________________________ 
polycarbonates polycarbonate Z resin 
acrylic resin methacrylic resin 
polyvinyl chloride 
polyvinylidene chloride 
polystyrene styrene-butadiene copolymer 
polyvinyl acetate 
polyvinyl formal 
polyvinyl butyral 
polyvinyl acetal 
polyvinyl carbazole 
styrene-alkyd resin 
silicone resin silicone-alkyd resin 
polyester phenolic resin 
polyurethane epoxy resin 
vinylidene chloride-acrylonitrile copolymer 
vinyl chloride-vinyl acetate copolymer 
vinyl chloride-vinyl acetate-maleic anhydride 
copolymer. 
______________________________________ 
These binders may be used either on their own or as admixtures. The carrier 
generation material is generally used in an amount of 10 -600 parts by 
weight, preferably 50-400 parts by weight, per 100 parts by weight of the 
binder, and the carrier transport material is generally used in an amount 
of 10-500 parts by weight per 100 parts by weight of the binder. 
The thus formed carrier generation layer preferably has a thickness of 
0.01-20 .mu.m, with the range of 0.05-5 .mu.m being more preferred. The 
carrier transport layer generally has a thickness of 1-100 .mu.m, 
preferably 5-30 .mu.m. 
In order to improve sensitivity or reduce residual potential or fatigue due 
to cyclic use, the light-sensitive layer of the electrophotographic 
photoreceptor of the present invention may contain one or more 
electron-accepting materials. Useful electron-accepting materials are 
selected from among the following compounds having high electron affinity: 
succinic anhydride, maleic anhydride, dibromosuccinic anhydride, phthalic 
anhydride, tetrachlorophthalic anhydride, totrabromophthalic anhydride, 
3-nitrophthalic anhydride, 4-nitrophthalic anhydride, pyromellitic 
anhydride, mellitic anhydride, tetracyanoethylene, 
tetracyanoquinodimethane, o-dinitrobenzene, m-dinitrobenzene, 
1,3,5-trinitrobenzene, p-nitrobenzonitrile, picryl chloride, quinone 
chlorimide, chloranil, bromanil, dichlorodicyano-p-benzoquinone, 
anthraquinone, dinitroanthraquinone, 9-fluorenylidene-(malonodinitrile), 
polynitro-9-fluorenylidene-(malonodinitrile), picric acid, o-nitrobenzoic 
acid, p-nitrobenzoic acid, 3,5-dinitrobenzoic acid, pentafluorobenzoic 
acid, 5-nitrosalicylic acid, 3,5-dinitrosalicylic acid, phthalic acid, and 
mellitic acid. 
These electron-accepting materials are used in such amounts that the weight 
ratio of carrier generation material to electron-accepting material is in 
the range of from 100:0.01 to 100:200, preferably from 100:0.1 to 100:100. 
Antioxidants, photo-stabilizers and other agents to prevent deterioration 
may be incorporated in the light-sensitive layer for the purpose of 
improving its storage stability, endurance, and resistance to 
environments. 
The support on which the light-sensitive layer is to be formed may be a 
metal plate, a metal drum or a thin conductive layer that is made of a 
conductive polymer, a conductive compound such as indium oxide or a metal 
such as aluminum or palladium and which is coated, vapor-deposited, 
laminated or otherwise formed on a substrate such as paper or a plastic 
film. 
Having the construction described above, the electrophotographic 
photoreceptor of the present invention has improved charging 
characteristic, sensitivity characteristic and resistance to cyclic use as 
will be understood from the examples that follow. 
SYNTHESIS EXAMPLE 1 
Titanium tetrachloride (14.7 ml) was added dropwise to a mixture of 
phthalodinitrile (65 g) and .alpha.-chloronaphthalene (500 ml) in a 
nitrogen stream. Thereafter, the reaction mixture was slowly heated to 
200.degree. C. and stirred for 3 h at 200.degree.-220.degree. C. to 
complete the reaction. Subsequently, the reaction mixture was left to cool 
to 130.degree. C. and filtered while hot. The cake on the filter was 
washed with .alpha.-chloronaphthalene, washed with methanol several times 
and further washed with hot water (80.degree. C.) several times. 
To the thus obtained Nutsche cake, o-dichlorobenzene was added and the 
mixture was milled with a sand grinder at a temperature in the range of 
40.degree.-60.degree. C. After dilution with methanol, the mixture was 
filtered and washed with acetone and methanol to obtain a sample of the 
titanyl phthalocyanine that is to be used in the present invention. As 
shown in FIG. 4, this titanyl phthalocyanine was a crystal having a 
maximum intensity peak at a Bragg angle (2 .theta.) of 27.3.degree. and 
characteristic peaks at 9.5.degree., 9.7.degree., 11.7.degree. and 
24.1.degree. in X-ray diffraction. At the same time, it contained a small 
amount of .alpha.-titanyl phthalocyanine. 
SYNTHESIS EXAMPLE 2 
The Nutsche cake obtained in Synthesis Example 1 was dried and a portion (5 
g) of it was stirred in 100 g of 96% sulfuric acid at 3.degree.-5.degree. 
C. The sulfuric acid solution obtained by subsequent filtration was poured 
into 1.5 liters of water and the precipitating crystal wa recovered by 
filtration. This crystal was washed with water repeatedly until the 
washings became neutral. 
To the thus obtained Nutsche cake, 1,2-dichloroethane was added and the 
mixture was stirred at room temperature for 1 h. By subsequent filtration 
and washing with methanol, a sample of the crystal to be used in the 
present invention was obtained. As shown in FIG. 5, this crystal had a 
maximum intensity peak at a Bragg angle (2 .theta.) of 27.3.degree. and 
characteristic peaks at 9.6.degree., 11.7.degree. and 24.1.degree. 
COMATIVE SYNTHESIS EXAMPLE 1 
The Nutsche cake obtained in Synthesis Example 2 was dried and milled in 
the presence of methyl cellosolve to obtain .alpha.-titanyl phthalocyanine 
having the X-ray diffractometer scan shown in FIG. 6. 
EXAMPLE 1 
Three parts by weight (all "parts" to that are appear hereinafter are on a 
weight basis) of an ethylene-vinyl acetate copolymer ("Sumitate KAl0" of 
Sumitomo Chemical Co., Ltd.) was dissolved in 100 parts of toluene with 
heat and the solution was passed through a 0.6-.mu.m filter. It was then 
dip-coated onto the surface of an aluminum drum to form an intermediate 
layer 0.5 .mu.m thick. 
Three parts of the titanyl phthalocyanine obtained in Synthesis Example 2 
which had the X-ray diffractometer scan shown in FIG. 5 and 20 parts of a 
binder resin (silicone resin "KR-5240" of Shin-Etsu Chemical Co., Ltd. 
dissolved in 15% xylene/butanol) were dispersed in 100 parts of methyl 
ethyl ketone (dispersion medium) by means of a sand mill. The dispersion 
was dip-coated onto the previously formed intermediate layer to form a 
carrier generation layer 0.2 .mu.m thick. Subsequently, a solution having 
1 part of a carrier transport material (T-1), 1.5 parts of a 
polycarbonate resin ("Jupilon Z200" of Mitsubishi Gas Chemical Co., Inc.) 
and a trace amount of silicone oil ("KF-54" of Shin-Etsu Chemical Co., 
Ltd.) dissolved in 10 parts of 1,2-dichloroethane was dip-coated onto the 
carrier generation layer and dried to form a carrier transport layer 25 
.mu.m thick. The so fabricated photoreceptor was designated as sample No. 
1. The absorption spectrum of this photoreceptor was as shown in FIG. 7. 
COMATIVE EXAMPLE 1 
A comparative photoreceptor was fabricated by repeating the procedure of 
Example 1 except that the titanyl phthalocyanine having the X-ray 
diffractometer scan shown in FIG. 5 was replaced by a comparative titanyl 
phthalocyanine having the X-ray diffractometer scan shown in FIG. 6. This 
comparative photoreceptor was designated as comparative sample No. 1. 
COMATIVE EXAMPLE 2 
Another comparative photoreceptor was fabricated as in Example 1 except 
that no intermediate layer was provided. This comparative photoreceptor 
was designated as comparative sample No. 2. 
COMATIVE EXAMPLE 3 
Still another comparative photoreceptor was fabricated as in Example 1 
except that the intermediate layer was composed of a polyester resin 
("Vylon 300" of Toyobo Co., Ltd.). This comparative photoreceptor was 
designated as comparative sample No. 3. 
COMATIVE EXAMPLE 4 
Yet another comparative photoreceptor was fabricated as in Example 1 except 
that the intermediate layer was composed of a polycarbonate resin 
("Panlite L-1250" of Teijin Chemicals Ltd.). This comparative 
photoreceptor was designated as comparative sample No. 4. 
EXAMPLES 2-4 
Photoreceptors were fabricated as in Example 1 except that the intermediate 
layer was composed of one of the ethylene copolymers shown in Table 1 
below. These photoreceptors were designated as sample Nos. 2-4. 
EXAMPLE 5 
Four parts of a soluble nylon resin ("Lakkamide 5003" of Dainippon Ink & 
Chemicals Co., Inc.) was dissolved in 100 parts of methanol with heat and 
the solution was passed through a 0.6-.mu.m filter. It was then dip-coated 
onto the surface of an aluminum drum to form an intermediate layer 0.6 
.mu.m thick. Three parts of the titanyl phthalocyanine prepared in 
Synthesis Example 1 and which had the X-ray diffractometer scan shown in 
FIG. 4 and 1.5 parts of a polyvinyl butyral resin ("XYHL" of Union Carbide 
Corporation) were dispersed in 100 parts of methyl ethyl ketone 
(dispersion medium) by means of a sand mill. The resulting dispersion was 
dip-coated onto the previously formed intermediate layer to form a carrier 
generation layer 0.3 .mu.m thick. Subsequently, a solution having 1 part 
of a carrier transport material (T-2), 1.3 parts of a polycarbonate resin 
("Panlite K-1300" of Teijin Chemicals Ltd.) and a trace amount of silicone 
oil ("KF54" of Shin-Etsu Chemical Co., Ltd.) dissolved in 10 parts of 
1,2-dichloroethane was dip-coated onto the carrier generation layer and 
dried to form a carrier transport layer 20 .mu.m thick. The so fabricated 
photoreceptor was designated as sample No. 5. The absorption spectrum of 
this photoreceptor was as shown in FIG. 8. 
EXAMPLES 6 AND 7 
Additional photoreceptors were fabricated as in Example 5 except that the 
intermediate layer was composed of one of the polyamide resins shown in 
Table 1. The so fabricated photoreceptors were designated as sample Nos. 6 
and 7. 
TABLE 1 
______________________________________ 
Example 
No. Sample No. Intermediate layer 
______________________________________ 
2 2 Sumitate KA-20 (Sumitomo 
Chemical Co., Ltd.) 
3 3 Evaflex A-703 (Mitsui Du Pont 
Polychemical Co., Ltd.) 
4 4 Evaflex A-704 (Mitsui Du Pont 
Polychemical Co., Ltd.) 
5 5 Lakkamide 5003 (Dainippon Ink 
& Chemicals Inc.) 
6 6 CM 8000 (Toray Industries, 
Ltd.) 
7 7 Diamide X1874M (Daicel-Hulse 
Co., Ltd.) 
______________________________________ 
Evaluation 
The samples were set in a laser printer adapted from "U-Bix 1550" of Konica 
Corp. and equipped with Laser Diode as a light source. The grid voltage 
was adjusted so that the potential in the unexposed area, V.sub.H, would 
be -700.+-.10 volts, and the potential in the exposed area, V.sub.L, was 
measured upon irradiation at 0.7 nW. Reversal development was effected at 
a developing bias of -600 volts and the quality of copy image was 
evaluated in terms of black spots in the white background by counting the 
number of black spots (.gtoreq.0.05 mm.PHI.) per square centimeter with an 
image analyzer "Ominicon Model 3000" (Shimadzu Corp.). The results were 
evaluated by the following criteria: O, no more than one black point per 
cm.sup.2 ; .DELTA., 2-10 black spots per cm.sup.2 ; X, 11 or more black 
spots per cm.sup.2. The results of evaluation are shown in the following 
table 2. 
TABLE 2 
______________________________________ 
Sample No. V.sub.L (V) 
Black spot 
______________________________________ 
Sample 1 -30 .circle. 
Sample 2 -30 .circle. 
Sample 3 -35 .circle. 
Sample 4 -30 .circle. 
Sample 5 -45 .circle. 
Sample 6 -45 .circle. 
Sample 7 -50 .circle. 
Comparative sample 1 
-80 X 
Comparative sample 2 
-25 X 
Comparative sample 3 
-30 X 
Comparative sample 4 
-30 X 
______________________________________ 
As is clear from the above results, the electrophotographic photoreceptors 
fabricated in accordance with the present invention had high sensitivity 
and yet the image produced had few defects, in particular, very few black 
spots when reversal development was effected.