An electrophotographic photoconductor contains at least a furan derivate or a thiophene derivate as the charge transport agent in a photoconductive layer thereof.

BACKGROUND OF THE INVENTION 
The present invention relates to a photoconductive layer of the 
electrophotographic photoconductors used in devices such as printers and 
copying machines that employ electrophotographic processes. More 
specifically, the present invention relates to constituent materials of 
the photoconductive layer. 
The photosensitive materials of a conventional electrophotographic 
photoconductor (hereinafter simply referred to as a "photoconductor") used 
for devices such as printers, facsimiles, digital copying machines and 
analog copying machines, that employ electrophotographic processes, 
include inorganic photoconductive materials such as selenium and selenium 
alloys, inorganic photoconductive materials such as zinc oxide and cadmium 
oxide dispersed into a resin binder, organic photoconductive materials 
such as poly-N-vinylcarbazole and poly(vinyl anthracene), and other 
organic photoconductive materials such as phthalocyanine compounds and 
bisazo compounds dispersed into a resin binder or deposited by vacuum 
deposition. 
It is required for the photoconductor to exhibit the functions for 
retaining surface charges in the dark, for generating electric charges in 
response to the received light, and for transporting the electric charges 
in response to the received light. The photoconductor may be classified 
into two types: 1) the mono-layered-type that exhibits the above described 
functions by one single photoconductive layer and 2) the so-called 
laminate-type consists of a layer mainly for charge generation, and a 
second layer for charge retention in the dark and charge transport in 
response to the received light. 
For image formation by the electrophotographic techniques and with these 
types of photoconductors, Carlson's process can be applied as an example. 
The Carlson's process for image formation includes the steps of 1) 
charging of the photoconductor by corona discharge in the dark, 2) 
formation of electrostatic latent images of the letters and figures in a 
manuscript on the charged surface of the photoconductor, 3) development of 
the electrostatic latent images with toner, and 4) fixing of the developed 
toner images on a paper and such carriers. The photoconductor is reused 
after removal of the charge, removal of the residual toner, and removal of 
the optical charge. 
Various image formation steps are employed in the Carlson's process. The 
corotron method or the scrotron method that uses metal wire and the 
contact charging method that uses the charging brush or charging roller 
are adopted for charging the photoconductor. Methods such as the 
two-components development method, nonmagnetic-single-component 
development method and magnetic-single-component development method are 
used in the development step. 
Recently, the organic photoconductors have been developed by virtue of the 
flexibility, thermal stability and ease of film formation thereof. U.S. 
Pat. No. 3,484,237 discloses a photoconductor that includes poly-N-vinyl 
carbazole and 2,4,7-trinitrofluorenone. Japanese Unexamined Laid Open 
Patent Application No. S47-37543 discloses a photoconductor that includes 
an organic pigment as the main component thereof. Japanese Unexamined Laid 
Open Patent Application No. S47-10785 discloses a photoconductor that 
includes an eutectic complex consisting of a dye and resin as the main 
component thereof. At present, the function-separation-type organic 
photoconductors, which include a charge generation layer and a charge 
transport layer, are mainly used. The charge generation layer comprises 
metal-free phthalocyanine, metal phthalocyanine such as titanyl 
phthalocyanine or azo compound and a resin binder. The charge transport 
layer comprises a hydrazone compound, styryl compound, diamine compound or 
butadiene compound and a resin binder. 
Among the function-separation-type photoconductors which laminate a charge 
generation layer on a conductive substrate and a charge transport layer on 
to the charge generation layer, negative-charging photoconductors exhibit 
sensitivity when the photoconductor surface is charged negatively, because 
the hole contributes to charge transport due to the nature of the charge 
transport material that functions as the electron donor. However, the 
corona discharge for negative-charging is unstable compared with the 
corona discharge for positive-charging. The corona discharge for 
negative-charging generates ozone and nitrogen oxide. The photoconductor 
surface is deteriorated physically and chemically by the ozone and 
nitrogen oxide absorbed thereto. Ozone and nitrogen oxide are very 
hazardous for the environmental safety. Accordingly, positive-charging 
photoconductors can be in practice more freely used and more widely used 
than negative-charging photoconductors. 
Various positive-charging photoconductors have been proposed. Some 
positive-charging photoconductors, which include a single-layered 
photoconductive layer comprising a charge generation agent and a charge 
transport agent, both dispersed into a resin binder, have been put into 
practical use. However, the sensitivity of these positive-charging 
photoconductors of the single-layered type is not so high enough to be 
applicable to the high speed machines. More improvements are necessary for 
repeatedly using the positive-charging photoconductors of the 
single-layered type. 
Laminate-type positive-charging photoconductors for high-speed use may be 
constructed by laminating a charge generation layer on a charge transport 
layer. However, corona discharge, light irradiation and mechanical wear 
pose problems of stability for repeated use of the photoconductor, since 
the charge generation layer is exposed on the surface of the 
photoconductor. The protection layer, disposed on the charge generation 
layer to avoid the mechanical wear of the charge generation layer, is 
problematic for improving the sensitivity and electrical properties of the 
photoconductor. 
Laminate-type positive-charging photoconductors which include a charge 
transport layer on a charge generation layer have been proposed. The 
charge transport materials including 2,4,7-trinitrofluorenone may be used. 
However, 2,4,7-trinitro-9-fluorenone is a carcinogen. The Japanese 
Unexamined Laid Open Patent Applications No. S50-131941, No. H06-59483 and 
No. H06-123986 disclose cyano compounds and quinone compounds as the 
charge transport agent. Nonetheless, no charge transport agent that can be 
satisfactorily used for the laminate-type positive-charging photoconductor 
has yet been obtained. 
Although the organic photoconductive materials have many merits which the 
inorganic photoconductive materials do not have, the conventional organic 
photoconductive materials do not exhibit all the properties required for 
electrophotographic photoconductors. It is required to fabricate a highly 
sensitive photoconductor that exhibits little change in the properties 
thereof after the photoconductor is continuously used in the 
electrophotographic apparatus continuous for a long time. Especially, the 
customer's demands are increasing for photoconductors, which can endure 
long continuous use in various electrophotographic apparatuses provided 
the foregoing with various imaging processes. The photosensitivity of the 
conventional laminate-type photoconductors is insufficient. Practical long 
use of the conventional laminate-type photoconductors causes charge 
potential lowering, residual potential rise, sensitivity lowering and such 
problems to be solved. Thus, a technology that facilitates realizing all 
the favorable properties for the electrophotographic photoconductor has 
not been established so far. 
OBJECTS AND SUMMARY OF THE INVENTION 
In view of the foregoing it is an object of the present invention to 
overcome the limitations of prior art. 
It is another object of the invention to provide an electrophotographic 
photoconductor that is stable enough to endure repeated continuous use for 
extended practical use in electrophotographic apparatuses. 
It is another object of the present invention to provide an 
electrophotographic photoconductor that can afford to be adaptable to 
various electrophotographic apparatuses which employ various known methods 
such as the corotron method or the scrotron method that uses metal wire 
for charging, which employ the contact charging method that uses the 
charging brush or charging roller for charging, which employ the two 
components-development method, which employ the 
nonmagnetic-single-component development method or which employ the 
magnetic-single-component development method. 
It is still another object of the invention to provide a highly sensitive 
electrophotographic photoconductor that exhibits excellent electrical 
properties in the positive-charging mode. It is a further object of the 
invention to provide an electrophotographic photoconductor adaptable to 
copying machines and printers. 
The present inventors have found that the foregoing problems are solved by 
the electrophotographic photoconductor that contains at least one charge 
transport agent selected from specific furan derivatives and thiophene 
derivatives in the photoconductive layer. 
According to an aspect of the invention, there is provided an 
electrophotographic photoconductor that includes a conductive substrate; a 
photoconductive layer on the conductive substrate; the photoconductive 
layer containing at least one of charge transport agents comprising furan 
derivatives and thiophene derivatives which are described by the general 
formula (I) in FIG. 4(a), where A is a hydrogen atom, substituted or 
non-substituted alkyl group, or substituted or non-substituted aromatic 
group; R.sup.1 is a hydrogen atom, halogen atom, substituted or 
non-substituted alkyl group, alkoxy group, alkylamino group, nitro group, 
cyano group, substituted or non-substituted aromatic group, or substituted 
or non-substituted heterocyclic group; R.sup.2 is a hydrogen atom, halogen 
atom, substituted or non-substituted alkyl group, alkoxy group, alkylamino 
group, nitro group, cyano group, substituted or non-substituted aromatic 
group, or substituted or non-substituted heterocyclic group; R.sup.3 is a 
hydrogen atom, halogen atom, substituted or non-substituted alkyl group, 
or substituted or non-substituted aromatic group; R.sup.4 is a hydrogen 
atom, halogen atom, substituted or non-substituted alkyl group, or 
substituted or non-substituted aromatic group; R.sup.5 is a cyano group, 
or alkoxycarbonyl group; R.sup.6 is a cyano group, or alkoxycarbonyl 
group; and X is an oxygen atom or sulfur atom. 
According to the present invention, substituents for substituted alkyls 
include halogen atoms; aryl groups such as, for example, phenyl groups; 
and heterocyclic groups, such as, for example, thienyl groups. 
According to the present invention, substitutents for substituted 
heterocyclics include halogen atoms; alkyl groups, such as, for example, 
methyl groups and ethyl groups; aryl groups, such as, for example, phehnyl 
gorups; and heterocyclic groups, such as, for example, thienyl groups. 
According to the present invention, substituents for substituted aromatics 
include halogen atoms; alkyl groups, such as, for example, methyl groups 
and ethyl groups; amino groups, such as, for example, dialkylamino groups; 
aryl groups, such as, for example, phenyl groups; and heterocyclic groups, 
such as, for example, thienyl groups. 
According to another aspect of the invention, there is provided an 
electrophotographic photoconductor that includes a conductive substrate; a 
photoconductive layer on the conductive substrate; the photoconductive 
layer containing at least one of charge transport agents comprising furan 
derivatives and thiophene derivatives described by the general formula 
(II) in FIG. 4(b), where R.sup.13 is a hydrogen atom, halogen atom, 
substituted or non-substituted alkyl group, substituted or non-substituted 
aromatic group, or substituted or non-substituted heterocyclic group; 
R.sup.14 is a hydrogen atom, halogen atom, substituted or non-substituted 
alkyl group, substituted or non-substituted aromatic group, or substituted 
or non-substituted heterocyclic group; R.sup.15 is a hydrogen atom, 
halogen atom, substituted or non-substituted alkyl group, substituted or 
non-substituted aromatic group, or substituted or non-substituted 
heterocyclic group; R.sup.16 is a hydrogen atom, halogen atom, substituted 
or non-substituted alkyl group, substituted or non-substituted aromatic 
group, or substituted or non-substituted heterocyclic group; R.sup.19 is a 
hydrogen atom, substituted or non-substituted alkyl group, or substituted 
or non-substituted aromatic group; R.sup.20 is a hydrogen atom, 
substituted or non-substituted alkyl group, or substituted or 
non-substituted aromatic group; R.sup.11 is a cyano group, or 
alkoxycarbonyl group; R.sup.12 is a cyano group, or alkoxycarbonyl group; 
R.sup.17 is a cyano group, or alkoxycarbonyl group; R.sup.18 is a cyano 
group, or alkoxycarbonyl group; and X is an oxygen atom or sulfur atom. 
According to the present invention, substituents for substituted alkyls 
include halogen atoms; aryl groups such as, for example, phenyl groups; 
and heterocyclic groups, such as, for example, thienyl groups. 
According to the present invention, substitutents for substituted 
heterocyclics include halogen atoms; alkyl groups, such as, for example, 
methyl groups and ethyl groups; aryl groups, such as, for example, phenyl 
groups; and heterocyclic groups, such as, for example, thienyl groups. 
According to the present invention, substituents for substituted aromatics 
include halogen atoms; alkyl groups, such as, for example, methyl groups 
and ethyl groups; amino groups, such as, for example, dialkylamino groups; 
aryl groups, such as, for example, phenyl groups; and heterocyclic groups, 
such as, for example, thienyl groups. 
Advantageously, R.sup.19 and R.sup.20 in the general formula (II) form a 
ring. 
The furan derivatives and the thiophene derivatives described by the 
general formulas (I) and (II) have not been used for the 
electrophotographic photoconductor. The present inventors have 
investigated application of such furan derivatives and thiophene 
derivatives described by the general formulas (I) and (II) and discovered 
their advantageous use. 
The photoconductor according to the invention exhibits high sensitivity. 
Further, the electrical potential characteristics and sensitivity 
characteristics of the photoconductor of the invention are not 
deteriorated by the long term use in various electrophotographic 
apparatuses provided with the foregoing various imaging processes. That 
is, excellent electrophotographic properties are realized by adding the 
furan derivatives or the thiophene derivatives described by the general 
formula (I) or (II) to the photoconductive layer. 
By using at least one of the furan derivatives or the thiophene derivatives 
as the charge transport agent, a highly sensitive and electrically 
excellent photoconductor that can be used in the positive-charging mode is 
obtained. 
Briefly stated, an electrophotographic photoconductor contains at least a 
furan derivative or a thiophene derivative as the charge transport agent 
in a photoconductive layer thereof. 
According to an embodiment of the present invention, a charge transport 
compound in a photoconductive layer, wherein the charge transport compound 
is a furan derivative or a thiophene derivative, wherein the charge 
transport compound is described by a general formula (I): 
##STR1## 
A being a hydrogen atom, substituted or non-substituted alkyl group, or 
substituted or non-substituted aromatic group; 
R.sup.1 being a hydrogen atom, halogen atom, substituted or non-substituted 
alkyl group, alkoxy group, alkylamino group, nitro group, cyano group, 
substituted or non-substituted aromatic group, or substituted or 
non-substituted heterocyclic group; 
R.sup.2 being a hydrogen atom, halogen atom, substituted or non-substituted 
alkyl group, alkoxy group, alkylamino group, nitro group, cyano group, 
substituted or non-substituted aromatic group, or substituted or 
non-substituted heterocyclic group; 
R.sup.3 being a hydrogen atom, halogen atom, substituted or non-substituted 
alkyl group, or substituted or non-substituted aromatic group; 
R.sup.4 being a hydrogen atom, halogen atom, substituted or non-substituted 
alkyl group, or substituted or non-substituted aromatic group; 
R.sup.5 being a cyano group, or alkoxycarbonyl group; 
R.sup.6 being a cyano group, or alkoxycarbonyl group; and 
X being an oxygen atom or sulfur atom. 
According to another embodiment of the present invention, an 
electrophotographic photoconductor comprises a conductive substrate, a 
photoconductive layer on the conductive substrate, the photoconductive 
layer comprising at least one charge transport agent, the charge transport 
agent comprising at least one furan derivative or thiophene derivative, 
the furan derivative and thiophene derivative being described by the 
following general formula (I): 
##STR2## 
A being a hydrogen atom, substituted or non-substituted alkyl group, or 
substituted or non-substituted aromatic group; 
R.sup.1 being a hydrogen atom, halogen atom, substituted or non-substituted 
alkyl group, alkoxy group, alkylamino group, nitro group, cyano group, 
substituted or non-substituted aromatic group, or substituted or 
non-substituted heterocyclic group; 
R.sup.2 being a hydrogen atom, halogen atom, substituted or non-substituted 
alkyl group, alkoxy group, alkylamino group, nitro group, cyano group, 
substituted or non-substituted aromatic group, or substituted or 
non-substituted heterocyclic group; 
R.sup.3 being a hydrogen atom, halogen atom, substituted or non-substituted 
alkyl group, or substituted or non-substituted aromatic group; 
R.sup.4 being a hydrogen atom, halogen atom, substituted or non-substituted 
alkyl group, or substituted or non-substituted aromatic group; 
R.sup.5 being a cyano group, or alkoxycarbonyl group; 
R.sup.6 being a cyano group, or alkoxycarbonyl group; and 
X being an oxygen atom or sulfur atom. 
According to an embodiment of the present invention, a method to make a 
photosensitive body by forming a photosensitive layer on a substrate, the 
photosensitive layer includes a charge transport compound wherein the 
charge transport compound is a furan derivative or thiophene derivative 
described by a general formula (I): 
##STR3## 
A being a hydrogen atom, substituted or non-substituted alkyl group, or 
substituted or non-substituted aromatic group; 
R.sup.1 being a hydrogen atom, halogen atom, substituted or non-substituted 
alkyl group, alkoxy group, alkylamino group, nitro group, cyano group, 
substituted or non-substituted aromatic group, or substituted or 
non-substituted heterocyclic group; 
R.sup.2 being a hydrogen atom, halogen atom, substituted or non-substituted 
alkyl group, alkoxy group, alkylamino group, nitro group, cyano group, 
substituted or non-substituted aromatic group, or substituted or 
non-substituted heterocyclic group; 
R.sup.3 being a hydrogen atom, halogen atom, substituted or non-substituted 
alkyl group, or substituted or non-substituted aromatic group; 
R.sup.4 being a hydrogen atom, halogen atom, substituted or non-substituted 
alkyl group, or substituted or non-substituted aromatic group; 
R.sup.5 being a cyano group, or alkoxycarbonyl group; 
R.sup.6 being a cyano group, or alkoxycarbonyl group; and 
X being an oxygen atom or sulfur atom. 
According to another embodiment of the present invention, a charge 
transport compound in a photoconductive layer, wherein the charge 
transport compound is a furan derivative or thiophene derivative described 
by a general formula (II): 
##STR4## 
R.sup.13 being a hydrogen atom, halogen atom, substituted or 
non-substituted alkyl group, substituted or non-substituted aromatic 
group, or substituted or non-substituted heterocyclic group; 
R.sup.14 being a hydrogen atom, halogen atom, substituted or 
non-substituted alkyl group, substituted or non-substituted aromatic 
group, or substituted or non-substituted heterocyclic group; 
R.sup.15 being a hydrogen atom, halogen atom, substituted or 
non-substituted alkyl group, substituted or non-substituted aromatic 
group, or substituted or non-substituted heterocyclic group; 
R.sup.16 being a hydrogen atom, halogen atom, substituted or 
non-substituted alkyl group, substituted or non-substituted aromatic 
group, or substituted or non-substituted heterocyclic group; 
R.sup.19 being a hydrogen atom, substituted or non-substituted alkyl group, 
or substituted or non-substituted aromatic group; 
R.sup.20 being a hydrogen atom, substituted or non-substituted alkyl group, 
or substituted or non-substituted aromatic group; 
R.sup.11 being a cyano group, or alkoxycarbonyl group; 
R.sup.12 being a cyano group, or alkoxycarbonyl group; 
R.sup.17 being a cyano group, or alkoxycarbonyl group; 
R.sup.18 being a cyano group, or alkoxycarbonyl group; and 
X being an oxygen atom or sulfur atom. 
According to an embodiment of the present invention, a charge transport 
compound above, wherein the R.sup.19 and R.sup.20 form a ring. 
According to another embodiment of the present invention, an 
electrophotographic photoconductor comprises a conductive substrate, a 
photoconductive layer on the conductive substrate, the photoconductive 
layer comprising at least one of charge transport agents, the charge 
transport agents comprising furan derivatives and thiophene derivatives, 
the furan derivatives and thiophene derivatives being described by the 
following general formula (II): 
##STR5## 
R.sup.13 being a hydrogen atom, halogen atom, substituted or 
non-substituted alkyl group, substituted or non-substituted aromatic 
group, or substituted or non-substituted heterocyclic group; 
R.sup.14 being a hydrogen atom, halogen atom, substituted or 
non-substituted alkyl group, substituted or non-substituted aromatic 
group, or substituted or non-substituted heterocyclic group; 
R.sup.15 being a hydrogen atom, halogen atom, substituted or 
non-substituted alkyl group, substituted or non-substituted aromatic 
group, or substituted or non-substituted heterocyclic group; 
R.sup.16 being a hydrogen atom, halogen atom, substituted or 
non-substituted alkyl group, substituted or non-substituted aromatic 
group, or substituted or non-substituted heterocyclic group; 
R.sup.19 being a hydrogen atom, substituted or non-substituted alkyl group, 
or substituted or non-substituted aromatic group; 
R.sup.20 being a hydrogen atom, substituted or non-substituted alkyl group, 
or substituted or non-substituted aromatic group; 
R.sup.11 being a cyano group, or alkoxycarbonyl group; 
R.sup.12 being a cyano group, or alkoxycarbonyl group; 
R.sup.17 being a cyano group, or alkoxycarbonyl group; 
R.sup.18 being a cyano group, or alkoxycarbonyl group; and 
X being an oxygen atom or sulfur atom. 
According to an embodiment of the present invention, an electrophotographic 
photoconductor above, wherein the R.sup.19 and R.sup.20 form a ring. 
According to another embodiment of the present invention, a method to make 
a photosensitive body by forming a photosensitive layer on a substrate, 
the photosensitive layer includes a charge transport compound wherein the 
charge transport compound is a furan derivative or thiophene derivative 
described by a general formula (II): 
##STR6## 
R.sup.13 being a hydrogen atom, halogen atom, substituted or 
non-substituted alkyl group, substituted or non-substituted aromatic 
group, or substituted or non-substituted heterocyclic group; 
R.sup.14 being a hydrogen atom, halogen atom, substituted or 
non-substituted alkyl group, substituted or non-substituted aromatic 
group, or substituted or non-substituted heterocyclic group; 
R.sup.15 being a hydrogen atom, halogen atom, substituted or 
non-substituted alkyl group, substituted or non-substituted aromatic 
group, or substituted or non-substituted heterocyclic group; 
R.sup.16 being a hydrogen atom, halogen atom, substituted or 
non-substituted alkyl group, substituted or non-substituted aromatic 
group, or substituted or non-substituted heterocyclic group; 
R.sup.19 being a hydrogen atom, substituted or non-substituted alkyl group, 
or substituted or non-substituted aromatic group; 
R.sup.20 being a hydrogen atom, substituted or non-substituted alkyl group, 
or substituted or non-substituted aromatic group; 
R.sup.11 being a cyano group, or alkoxycarbonyl group; 
R.sup.12 being a cyano group, or alkoxycarbonyl group; 
R.sup.17 being a cyano group, or alkoxycarbonyl group; 
R.sup.18 being a cyano group, or alkoxycarbonyl group; and 
X being an oxygen atom or sulfur atom. 
The above, and other objects, features and advantages of the present 
invention will become apparent from the following description read in 
conjunction with the accompanying drawings, in which like reference 
numerals designate the same elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
According to the present invention, an electrophotographic photoconductor 
includes a conductive substrate; a photoconductive layer on the conductive 
substrate; the photoconductive layer containing at least one of charge 
transport agents comprising furan derivatives and thiophene derivatives 
which are described by the general formula (I) in FIG. 4(a), where A is a 
hydrogen atom, substituted or non-substituted alkyl group, or substituted 
or non-substituted aromatic group; R.sup.1 is a hydrogen atom, halogen 
atom, substituted or non-substituted alkyl group, alkoxy group, alkylamino 
group, nitro group, cyano group, substituted or non-substituted aromatic 
group, or substituted or non-substituted heterocyclic group; R.sup.2 is a 
hydrogen atom, halogen atom, substituted or non-substituted alkyl group, 
alkoxy group, alkylamino group, nitro group, cyano group, substituted or 
non-substituted aromatic group, or substituted or non-substituted 
heterocyclic group; R.sup.3 is a hydrogen atom, halogen atom, substituted 
or non-substituted alkyl group, or substituted or non-substituted aromatic 
group; R.sup.4 is a hydrogen atom, halogen atom, substituted or 
non-substituted alkyl group, or substituted or non-substituted aromatic 
group; R.sup.5 is a cyano group, or alkoxycarbonyl group; R.sup.6 is a 
cyano group, or alkoxycarbonyl group; and X is an oxygen atom or sulfur 
atom. 
Preferably, A in the general formula (I) is a hydrogen atom, alkyl group 
containing from one to eight carbon atom or atoms, non-substituted phenyl 
group, non-substituted biphenyl group, non-substituted naphthyl group, 
phenyl group substituted by one or more halogen atom or atoms, phenyl 
group substituted by an alkyl group containing from one to eight carbon 
atom or atoms, or phenyl group substituted by an alkylamino group 
containing from one to eight carbon atom or atoms. 
Preferably, the alkyl group, alkoxy group and alkylamino group for R.sup.1 
and R.sup.2 in the general formula (I) contain from one to eight carbon 
atom or atoms. 
According to another embodiment of the present invention, there is provided 
an electrophotographic photoconductor that includes a conductive 
substrate; a photoconductive layer on the conductive substrate; the 
photoconductive layer containing at least one of charge transport agents 
comprising furan derivatives and thiophene derivatives described by the 
general formula (II) in FIG. 4(b), where R.sup.13 is a hydrogen atom, 
halogen atom, substituted or non-substituted alkyl group, substituted or 
non-substituted aromatic group, or substituted or non-substituted 
heterocyclic group; R.sup.14 is a hydrogen atom, halogen atom, substituted 
or non-substituted alkyl group, substituted or non-substituted aromatic 
group, or substituted or non-substituted heterocyclic group; R.sup.15 is a 
hydrogen atom, halogen atom, substituted or non-substituted alkyl group, 
substituted or non-substituted aromatic group, or substituted or 
non-substituted heterocyclic group; R.sup.16 is a hydrogen atom, halogen 
atom, substituted or non-substituted alkyl group, substituted or 
non-substituted aromatic group, or substituted or non-substituted 
heterocyclic group; R.sup.19 is a hydrogen atom, substituted or 
non-substituted alkyl group, or substituted or non-substituted aromatic 
group; R.sup.20 is a hydrogen atom, substituted or nonsubstituted alkyl 
group, or substituted or non-substituted aromatic group; R.sup.11 is a 
cyano group, or alkoxycarbonyl group; R.sup.12 is a cyano group, or 
alkoxycarbonyl group; R.sup.17 is a cyano group, or alkoxycarbonyl group; 
R.sup.18 is a cyano group, or alkoxycarbonyl group; and X is an oxygen 
atom or sulfur atom. 
Advantageously, R.sup.19 and R.sup.20 in the general formula (II) form a 
ring. 
Preferably, the alkyl group, alkoxy group and alkylamino group for R.sup.13 
through R.sup.16 in the general formula (II) contain from one to eight 
carbon atom or atoms. 
The furan derivatives and the thiophene derivatives described by the 
general formulas (I) and (II) are synthesized by conventionally known 
methods. The compounds described by the general formula (I) are easily 
synthesized by, for example, reacting the aldehyde compound described by 
the structural formula (Ia) in FIG. 5(a) and the reagent described by the 
structural formula (Ib) in FIG. 5(b) in an appropriate organic solvent, 
such as benzene and toluene, under alkaline presence. The compounds 
described by the general formula (II) are prepared easily by, for example, 
reacting the aldehyde described by the structural formula (IIa) in FIG. 
5(a) and the reagent described by the structural formula (IIb) in FIG. 
5(b) in an appropriate organic solvent, such as benzene and toluene, under 
alkaline presence. 
Examples of the furan derivatives and the thiophene derivatives represented 
by the general formula (I) are described in FIGS. 6(a) through 6(c). 
Further, examples of the furan derivatives and the thiophene derivatives 
represented by the general formula (II) are described in FIGS. 7(a) and 
7(b). 
Examples of the charge generation agent used in the present invention 
include phthalocyanine compounds (III-1) through (III-6) described in FIG. 
8(a), and azo compounds including the derivatives thereof (III-7) through 
(III-24) described in FIGS. 8(b) through 8(d). Various compounds (IV-1) 
through (IV-12) described in FIGS. 9(a) and 9(b) may be used in 
combination with the furan derivatives and the thiophene derivatives 
described by the general formulas (I) and (II). 
Examples of the resin binder for the charge transport layer include various 
polycarbonate resins (V-1) through (V-7) described in FIG. 10. Amine 
antioxidants, phenolic antioxidants, sulfur-containing antioxidants, 
phosphite antioxidants, phosphor containing antioxidants and benzopinacol 
antioxidants (VI-1) through (VI-45) described in FIGS. 11(a) through 11(f) 
are used in the photoconductive layer to prevent the photoconductive layer 
from being deteriorated by ozone. 
The present invention will be explained hereinafter with reference to the 
accompanied drawing figures which illustrate the photoconductive layer of 
the invention that contains the above compounds. 
In these figures, the reference numeral 1 designates a conductive 
substrate, 2 a photoconductive layer, 3 a charge generation layer, 4 a 
charge transport layer, and 5 a cover layer. 
The photoconductor shown in FIG. 1 is the so-called single-layered 
photoconductor that includes conductive substrate 1 and photoconductive 
layer 2 on conductive substrate 1. Photoconductive layer 2 contains a 
charge generation agent and a furan derivative or a thiophene derivative 
charge transport agent dispersed into a binder resin. Cover layer 5 is 
optionally formed on photoconductive layer 2. 
The photoconductor shown in FIG. 2 is the so-called laminate-type 
photoconductor that includes conductive substrate 1 and photoconductive 
layer 2 that includes charge generation layer 3 containing a charge 
generation agent and charge transport layer 4 containing a furan 
derivative or a thiophene derivative charge generation agent. 
The photoconductor shown in FIG. 3 has another laminate structure in which 
the order of layer lamination is reversed. In this laminate-type 
photoconductor, cover layer 5 is usually formed to protect charge 
generation layer 3. 
The furan derivative or the thiophene derivative in the present invention 
performs either (a) as a major charge transport material or (b) as one of 
additives in a charge transport layer as electron transport substance. In 
the case of (a), the furan derivative or the thiophene derivative is 
preferably contained at 30-70 wt %, and more preferably 40-60 wt % in a 
charge transport layer. In the case of (b), the furan derivative or 
thiophene derivative is contained preferably at 0.5-5% wt percent in a 
charge transport layer. In the case of (a), a single layered 
photosensitive body (FIG. 1) and a laminated photosensitive body of the 
type substrate/charge generation layer/charge transport layer (FIG. 2) are 
of a positive charging type. However, in the case of (b), a single layered 
photosensitive body (FIG. 1) and a laminated photosensitive body of the 
type substrate/charge transport layer/charge generation layer (FIG. 3) are 
of a positive charging type, but, a laminated photosensitive body of the 
type substrate/charge generation layer/charge transport layer (FIG. 2) is 
of a negative charging type. 
The photoconductor shown in FIG. 1 is manufactured, for example, by first 
preparing a dispersion liquid, prepared by dispersing a charge generation 
agent into a solution in which a charge transport agent and a binder resin 
are dissolved, and by coating the thus formed dispersion liquid onto a 
conductive substrate. If necessary, a cover layer is formed on the 
photoconductive layer by conventional coating methods. 
The photoconductor shown in FIG. 2 is manufactured as follows. The charge 
generation layer is formed, for example, by either 1) depositing a charge 
generation agent by vacuum deposition on the conductive substrate, or 2) 
by coating and drying a dispersion liquid, prepared by dissolving a charge 
generation agent into a solvent or by prepared by dispersing a charge 
generation agent into a binder resin, onto the conductive substrate. Then, 
the charge transport layer is formed by coating and drying a solution, 
into which a charge transport agent and a binder resin are dissolved, onto 
the charge generation layer. 
The photoconductor shown in FIG. 3 is manufactured as follows. The charge 
transport layer is formed, for example, by coating and drying a solution, 
into which was dissolved a charge transport agent and a binder resin are 
dissolved, on the conductive substrate. Then, the charge generation layer 
is formed by depositing a charge generation agent by vacuum deposition on 
the charge transport layer, or by coating and drying a dispersion liquid, 
prepared by dissolving a charge generation agent into a solvent or by 
dispersing a charge generation agent into a binder resin, on the charge 
transport layer. Then, a cover layer is formed on the charge generation 
layer by the conventional coating methods. 
Conductive substrate 1 functions as an electrode of the photoconductor and 
sustains the layers of the photoconductor. Conductive substrate 1 may be 
shaped as a cylindrical tube, plate or a film. Metals such as aluminum, 
stainless steel and nickel or glass and resin, treated to exhibit 
electrical conduction, are used for the conductive substrate 1. Insulating 
polymers such as casein, poly(vinyl alcohol), nylon, polyamide, melamine 
and cellulose, conductive polymers such as polythiophene, polypyrrole and 
polyaniline or polymers that contain metal oxide powders or low molecular 
weight compounds can be used for a surface coating for providing the 
substrate with needed electrical conductivity. 
As explained above, charge generation layer 3 is formed by depositing a 
charge generation agent by vacuum deposition, or by coating and drying a 
dispersion liquid, prepared by dissolving a charge generation agent into a 
solvent or by dispersing a charge generation agent into a binder resin. 
Charge generation layer 3 generates charges in response to the irradiated 
light. 
It is preferable for charge generation layer 3 to exhibit high charge 
generation efficiency and high efficiency of the generated charge 
injection into the charge transport layer 4. It is also preferable for the 
charge injection efficiency not to depend on the electric field and to be 
high enough even in the low electric field. 
Pigments and dyes such as phthalocyanine. (III-1) through (III-6), azo 
compounds (III-7) through (III-24), their derivatives, metal 
phthalocyanine such as titanyl phthalocyanine, quinone compounds, indigo 
compounds, cyanine compounds, squalium compounds, azulenium compounds and 
pyrilium compounds, selenium, and selenium compounds are used for the 
charge generation agent. An appropriate charge generation agent may be 
selected correspond to the wavelength range of the exposure light source 
used for image formation. The charge generation layer 3 is formed to be 5 
.mu.m or less, preferably 2 .mu.m or less, in thickness, since it is 
enough for the charge generation layer only to exhibit the charge 
generating function. The charge generation layer may contain a charge 
transport agent in addition to the charge generation agent as the main 
component thereof. 
Binder resin for the charge generation layer includes polycarbonate, 
polyester, polyamide, polyurethane, epoxy resin, poly(vinyl butyral), 
poly(vinyl acetal), phenoxy resin, silicone resin, acrylic resin, vinyl 
chloride resin, vinylidene chloride resin, vinyl acetate resin, formal 
resin, cellulose resin, their copolymers, their halides and their 
cyanoethyl compounds. These binder resins are used alone or in 
combination. 
Charge transport layer 4 is a coating film into that the furan derivative 
or the thiophene derivative described by the foregoing general formula (I) 
or (II) is dispersed. Charge transport layer 4 functions in the dark as an 
insulation layer that retains the charges of the photoconductive layer and 
transports the charges injected from the charge generation layer during 
light reception. Various compounds (IV-1) through (IV-12) may be used in 
combination as the charge transport agent. The charge transport layer 4 is 
preferably from 10 to 40 .mu.m in thickness. Various polycarbonate resins 
(V-1) through (V-7), polystyrene, polyacrylate, polyphenylene ether acryl, 
polyester, polymethacrylate, and their copolymers are used as the resin 
binder for the charge transport layer. 
Amine antioxidants, phenolic antioxidants, sulfur-containing antioxidants, 
phosphite antioxidants, phosphor containing antioxidants and benzopinacol 
antioxidants (VI-1) through (VI-45) may be used in the photoconductive 
layer to prevent the photoconductive layer from being deteriorated by 
ozone. 
Cover layer 5 retains in the dark the charge caused by the corona discharge 
and transmits the light to that the photoconductive layer is sensitive. It 
is required for cover layer 5 to transmit the exposure light to the 
photoconductive layer, to receive the generated charges injected thereto 
and to neutralize the surface charges. Organic insulating film materials 
such as polyester and polyamide may be used for the cover layer 5. 
Inorganic materials such as glass resins and SiO.sub.2, and stuffs such as 
metal and metal oxide which facilitate lowering the electrical resistance 
may be mixed to the organic insulative film materials. The coating 
materials are preferably transparent as much as possible in the wavelength 
region in which the foregoing charge generation agent absorbs light at its 
maximum. 
Though it depends on the composition thereof, the thickness of the cover 
layer may be set within an arbitrary range in which repeated use of the 
photoconductor may not cause adverse effects such as residual potential 
rise. 
EMBODIMENTS 
The present invention will be explained more in detail by way of the 
preferred embodiments below. 
First through Eighth Embodiments (E1 through E8) 
First through eighth embodiments (E1 through E8) are positive-charging 
photoconductors. 
First Embodiment (E1) 
Coating liquid for the photoconductive layer was prepared by mixing 20 
weight parts of X-type metal-free phthalocyanine (hereinafter abbreviated 
as "H2Pc"), 100 weight parts of a furan derivative (I-1), 100 weight parts 
of polyester resin (VYLON 200 supplied from TOYO BO. CO., LTD.) and 
tetrahydrofuran solvent in a mixer for 3 hr. The coating liquid was coated 
on an aluminum conductive substrate, 30 mm in outer diameter and 260 mm in 
length, such that the photoconductive layer may be 10 .mu.m in thickness 
after drying. 
Second Embodiment (E2) 
Coating liquid for the charge generation layer was prepared by mixing 70 
weight parts of titanyl phthalocyanine (hereinafter abbreviated as 
"TiOPc"), 30 weight parts of vinyl chloride copolymer and methylene 
chloride in a mixer for 3 hr. The charge generation layer was formed on an 
aluminum substrate by coating the thus prepared coating liquid such that 
the charge generation layer may be about 1 .mu.m in thickness. Then, 
coating liquid for the charge transport layer was prepared by mixing 100 
weight parts of a furan derivative (I-5), 100 weight parts of 
polycarbonate resin (PCZ-200 supplied from MITSUBISHI GAS CHEMICAL 
COMPANY, INC.), 0.1 weight parts of silicone oil (KP-340, supplied by 
Shinetsu Silicone Co., Ltd.) and methylene chloride. Finally, the coating 
liquid for the charge transport layer was coated on the charge generation 
layer such that charge transport layer may be about 10 .mu.m in thickness. 
Third Embodiment (E3) 
The photoconductor of the third embodiment was prepared in the similar 
manner as the second embodiment except that TiOPc of the second embodiment 
was replaced by a squalium pigment described by the structural formula in 
FIG. 12 and the furan derivative (I-5) of the second embodiment by a 
thiophene derivative (II-4). 
Fourth Embodiment (E4) 
The photoconductor of the fourth embodiment was prepared in the similar 
manner as the second embodiment except that TiOPc of the second embodiment 
was replaced by a bisazo pigment described by the structural formula in 
FIG. 13, the furan derivative (I-5) of the second embodiment by a 
thiophene derivative (I-13) and a polycarbonate resin (V-4) (TOUGHZET 
supplied from IDEMITSU KOSAN CO., LTD.) was used in the fourth embodiment. 
Fifth Embodiment (E5) 
The photoconductor of the fifth embodiment was prepared in the similar 
manner as the fourth embodiment except that a thiophene derivative (II-1) 
was used as the charge transport agent of the fifth embodiment. 
Sixth Embodiment (E6) 
The photoconductor of the sixth embodiment was prepared in the similar 
manner as the fourth embodiment except that a thiophene derivative (II-2) 
was used as the charge transport agent in the sixth embodiment. 
Seventh Embodiment (E7) 
The photoconductor of the seventh embodiment was prepared in the similar 
manner as the fourth embodiment except that a thiophene derivative (II-4) 
was used as the charge transport agent in the seventh embodiment. 
Eighth Embodiment (E8) 
The photoconductor of the eighth embodiment was prepared in the similar 
manner as the fourth embodiment except that the bisazo pigment of the 
fourth embodiment was replaced by a bisazo pigment described by the 
structural formula in FIG. 14 and a furan derivative (I-5) was used as the 
charge transport agent in the eighth embodiment. 
Evaluation 
The electrophotographic properties of the photoconductors fabricated as 
described above were evaluated. Initial surface potential Vs (V) when the 
photoconductor surface was positively charged by corona discharge at +4.5 
kV in the dark and surface potential Vd (V) after the photoconductor had 
been left in the dark for 5 seconds from the end of the corona discharge 
were measured. Then, sensitivity E1/2 (lux.multidot.s) was obtained by 
measuring a period of time (sec) until the surface potential Vd had been 
halved by irradiation of the white light to the photoconductor surface at 
the illuminance of 100 lux. Surface potential caused by 10 seconds 
irradiation of the white light at the illuminance of 100 lux was measured 
as the residual potential Vr (V). 
Since the photoconductors of the first through third embodiments are 
expected to be highly sensitive at long wavelengths, the 
electrophotographic properties of the first through third embodiments were 
measured also at the monochromatic light of 780 nm in wavelength. The 
surface potential Vs (V) and Vd (V) were measured in the same way as 
described above. Then, half decay exposure light quantity (.mu.J/cm.sup.2) 
was measured by irradiation of the monochromatic light (780 nm) of 1 .mu.W 
in place of the white light irradiation. Residual potential Vr (V) was 
measured by irradiating the monochromatic light for 10 seconds. The 
results of the evaluation are listed in Table 1. 
TABLE 1 
______________________________________ 
White light Monochromatic light (780 nm) 
Residual Half decay exposure 
Residual 
Sensitivity E.sub.1/2 
potential 
light quantity 
potential 
(lux .multidot. s) 
(V) (.mu.J/cm.sup.2) 
(V) 
______________________________________ 
Embodi- 
13.5 120 1.11 85 
ment 1 
Embodi- 
6.6 40 6.9 70 
ment 2 
Embodi- 
7.5 90 10.2 75 
ment 3 
Embodi- 
8.8 40 -- -- 
ment 4 
Embodi- 
11.3 90 -- -- 
ment 5 
Embodi- 
9.3 70 -- -- 
ment 6 
Embodi- 
10.0 60 -- -- 
ment 7 
Embodi- 
12.8 100 -- -- 
ment 8 
______________________________________ 
Ninth through Twenty Fourth Embodiments (E9 through E24), & Comparative 
Examples 1 through 5 
Ninth through twenty fourth embodiments (E9 through E24) and comparative 
examples 1 through 5 (C1 through C5) are negative-charging laminate-type 
photoconductors for which aluminum cylindrical substrates, 1 mm in 
thickness, 310 mm in length and 60 mm in outer diameter were used. The 
aluminum cylindrical substrates were cleaned and dried before use. 
Ninth Embodiment (E9) 
Coating liquid for resin coat film was prepared by dissolving 10 weight 
parts of alcohol-soluble polyamide copolymer resin (CM 8000 supplied from 
TORAY INDUSTRIES, INC.) into solvent mixture of 45 weight parts of 
methanol and 45 weight parts of methylene chloride. The coating liquid was 
coated on the aluminum cylindrical substrate tube by dip-coating and, then 
dried at 90.degree. C. for 30 min to form a resin coat film of 0.1 .mu.m 
in thickness for an intermediate layer. 
Then, coating liquid for the charge generation layer was prepared by 
dispersing 1 weight part of poly(vinyl acetal) resin (S.LEC KS-1 supplied 
from Sekisui Chemical Co., Ltd.) and 1 weight part of a bisazo charge 
generation agent (III-17) into 150 weight parts of methyl ethyl ketone in 
a ball mill for 24 hr. A charge generation layer of 0.2 .mu.m in thickness 
was formed on the intermediate layer by dip-coating of the coating liquid 
and by drying the coating liquid at 90.degree. C. for 30 min. 
Then, coating liquid for the charge transport layer was prepared by 
dissolving 50 weight parts of a hydrazone compound (IV-1), 50 weight parts 
of another hydrazone compound (IV-2), 100 weight parts of bisphenol 
A-type-biphenyl polycarbonate copolymer (V-4) (TOUGHZET supplied from 
IDEMITSU KOSAN CO., LTD.), 5 weight parts of a hindered phenolic compound 
(VI-2) and 1 weight part of a furan derivative (I-1) into 700 weight parts 
of dichloromethane. A charge transport layer of 20 .mu.m in thickness was 
formed on the charge generation layer by coating the coating liquid and by 
drying the coating liquid at 90.degree. C. for 30 min. 
Tenth Embodiment (E10) 
The photoconductor of the tenth embodiment was prepared in the similar 
manner as the ninth embodiment except that a furan derivative (I-5) was 
used in the tenth embodiment in place of the furan derivative (I-1) of the 
ninth embodiment. 
Eleventh Embodiment (E11) 
The photoconductor of the eleventh embodiment was prepared in the similar 
manner as the ninth embodiment except that a thiophene derivative (I-9) 
was used in the eleventh embodiment in place of the furan derivative (I-1) 
of the ninth embodiment. 
Twelfth Embodiment (E12) 
The photoconductor of the twelfth embodiment was prepared in the similar 
manner as the ninth embodiment except that a thiophene derivative (I-16) 
was used in the twelfth embodiment in place of the furan derivative (I-1) 
of the ninth embodiment. 
Thirteenth Embodiment (E13) 
The photoconductor of the thirteenth embodiment was prepared in the similar 
manner as the ninth embodiment except that a thiophene derivative (II-1) 
was used in the thirteenth embodiment in place of the furan derivative 
(I-1) of the ninth embodiment. 
Fourteenth Embodiment (E14) 
The photoconductor of the fourteenth embodiment was prepared in the similar 
manner as the ninth embodiment except that a thiophene derivative (II-4) 
was used in the fourteenth embodiment in place of the furan derivative 
(I-1) of the ninth embodiment. 
Fifteenth Embodiment (E15) 
The photoconductor of the fifteenth embodiment was prepared in the similar 
manner as the ninth embodiment except that a furan derivative (II-7) was 
used in the fifteenth embodiment in place of the furan derivative (I-1) of 
the ninth embodiment. 
Sixteenth Embodiment (E16) 
The photoconductor of the sixteenth embodiment was prepared in the similar 
manner as the ninth embodiment except that a furan derivative (II-10) was 
used in the sixteenth embodiment in place of the furan derivative (I-1) of 
the ninth embodiment. 
Seventeenth Embodiment (E17) 
The photoconductor of the seventeenth embodiment was prepared in the 
similar manner as the ninth embodiment except that a bisazo charge 
generation agent (III-7) was used in the seventeenth embodiment in place 
of the charge generation agent (III-17) of the ninth embodiment. 
Eighteenth Embodiment (E18) 
The photoconductor of the eighteenth embodiment was prepared in the similar 
manner as the ninth embodiment except that a bisazo charge generation 
agent (III-24) was used in the eighteenth embodiment in place of the 
charge generation agent (III-17) of the ninth embodiment. 
Nineteenth Embodiment (E19) 
The photoconductor of the nineteenth embodiment was prepared in the similar 
manner as the ninth embodiment except that the charge transport agents of 
the ninth embodiment was replaced by 50 weight parts of a hydrazone 
compound (IV-3) and 50 weight parts of a butadiene compound (IV-4) in the 
nineteenth embodiment. 
Twentieth Embodiment (E20) 
The photoconductor of the twentieth embodiment was prepared in the similar 
manner as the ninth embodiment except that the charge transport agents of 
the ninth embodiment was replaced by 50 weight parts of a diamine compound 
(IV-10) and 50 weight parts of a distyryl compound (IV-11) in the 
twentieth embodiment. 
Twenty First Embodiment (E21) 
The photoconductor of the twenty first embodiment was prepared in the 
similar manner as the ninth embodiment except that the resin (V-4) of the 
ninth embodiment was replaced by a polycarbonate resin (V-2) in the twenty 
first embodiment. 
Twenty Second Embodiment (E22) 
The photoconductor of the twenty second embodiment was prepared in the 
similar manner as the ninth embodiment except that the resin (V-4) of the 
ninth embodiment was replaced by a polycarbonate resin (V-6) in the twenty 
second embodiment. 
Twenty Third Embodiment (E23) 
The photoconductor of the twenty third embodiment was prepared in the 
similar manner as the ninth embodiment except that the antioxidant (VI-2) 
of the ninth embodiment was replaced by an antioxidant (VI-30) in the 
twenty third embodiment. 
Twenty Fourth Embodiment (E24) 
The photoconductor of the twenty fourth embodiment was prepared in the 
similar manner as the ninth embodiment except that the antioxidant (VI-2) 
of the ninth embodiment was replaced by an antioxidant (VI-37) in the 
twenty fourth embodiment. 
Comparative Example 1 (C1) 
The photoconductor of the comparative example 1 was prepared in the similar 
manner as the ninth embodiment except that the furan derivative of the 
ninth embodiment was not contained in the charge transport layer of the 
comparative example 1. 
Comparative Example 2 (C2) 
The photoconductor of the comparative example 2 was prepared in the similar 
manner as the seventeenth embodiment except that the furan derivative of 
the seventeenth embodiment was not contained in the charge transport layer 
of the comparative example 2. 
Comparative Example 3 (C3) 
The photoconductor of the comparative example 3 was prepared in the similar 
manner as the nineteenth embodiment except that the furan derivative of 
the nineteenth embodiment was not contained in the charge transport layer 
of the comparative example 3. 
Comparative Example 4 (C4) 
The photoconductor of the comparative example 4 was prepared in the similar 
manner as the twenty first embodiment except that the furan derivative of 
the twenty first embodiment was not contained in the charge transport 
layer of the comparative example 4. 
Comparative Example 5 (C5) 
The photoconductor of the comparative example 5 was prepared in the similar 
manner as the twenty third embodiment except that the furan derivative of 
the twenty third embodiment was not contained in the charge transport 
layer of the comparative example 5. 
Evaluation 
The electrophotographic properties of the photoconductors of the ninth 
through twenty fourth embodiments and the comparative examples 1 through 5 
were evaluated in the following way. 
The surface potential when the photoconductor surface was negatively 
charged by corona discharge at -6.0 kV in the dark for 10 seconds and 
surface potential after the photoconductor had been left in the dark for 5 
seconds from the end of the corona discharge were measured, and the 
retention rate VK5 of the surface potential 5 seconds afterward the corona 
discharge was obtained. Then, the half decay exposure light quantity 
E.sub.1/2 (lux.multidot.s) was obtained by measuring a period of time 
(sec) until the surface potential had been halved by irradiation of the 
white light to the photoconductor surface at the illuminance of 2 lux. 
The change of the surface potential during continuous use of the 
photoconductor was evaluated in an analog copying machine provided with 
the scrotron charging process and two-components developing mechanism. The 
charging mechanism, exposure mechanism and charge removal mechanism of the 
analog copying machine were fixed at certain outputs. Each photoconductor 
subjected to a running test that prints 50000 sheets of A4-size paper in 
an ordinary temperature and ordinary humidity environment. White paper 
potential Vw and black paper potential Vb were measured at the start and 
end of the running test, and the potential changes .DELTA.Vw and .DELTA.Vb 
were obtained. Table 2 lists the results. 
TABLE 2 
__________________________________________________________________________ 
Running test 
Charge 
Charge Initial 
Change 
Furan or 
generation 
transport 
Binder 
Anti- 
VK5 
E.sub.1/2 
Vw Vb .DELTA. Vw 
.DELTA. Vb 
Specimen 
thiophene 
agent 
agent resin 
oxidant 
(%) 
(lux.s) 
(V) 
(V) 
(V) 
(V) 
__________________________________________________________________________ 
E 9 I-1 III-17 
IV-1 
IV-2 
V-4 VI-2 
96.9 
0.90 
-47 
-605 
3 -2 
E 10 I-5 III-17 
IV-1 
IV-2 
V-4 VI-2 
98.0 
0.99 
-45 
-603 
3 -1 
E 11 I-9 III-17 
IV-1 
IV-2 
V-4 VI-2 
95.6 
1.02 
-45 
-605 
0 -3 
E 12 I-16 III-17 
IV-1 
IV-2 
V-4 VI-2 
96.5 
0.99 
-44 
-603 
5 0 
E 13 II-1 III-17 
IV-1 
IV-2 
V-4 VI-2 
97.0 
0.89 
-48 
-604 
4 2 
E 14 II-4 IIl-17 
IV-1 
IV-2 
V-4 VI-2 
95.6 
0.60 
-47 
-605 
0 -3 
E 15 II-7 III-17 
IV-1 
IV-2 
V-4 VI-2 
95.2 
0.90 
-45 
-607 
3 -3 
E 16 II-10 
III-17 
IV-1 
IV-2 
V-4 VI-2 
96.2 
1.02 
-45 
-605 
0 -1 
E 17 I-1 III-7 
IV-1 
IV-2 
V-4 VI-2 
96.8 
0.95 
-45 
-607 
5 -3 
E 18 I-1 III-24 
IV-1 
IV-2 
V-4 VI-2 
96.7 
0.92 
-45 
-605 
4 -1 
E 19 I-1 III-17 
IV-3 
IV-4 
V-4 VI-2 
97.2 
0.90 
-45 
-605 
2 -4 
E 20 I-1 III-17 
IV-10 
IV-11 
V-4 VI-2 
96.5 
0.96 
-45 
-607 
5 0 
E 21 I-1 III-17 
IV-1 
IV-2 
V-2 VI-2 
97.4 
1.02 
-45 
-605 
4 -3 
E 22 I-1 III-17 
IV-1 
IV-2 
V-6 VI-2 
95.8 
1.00 
-45 
-607 
2 -5 
E 23 I-1 III-47 
IV-1 
IV-2 
V-4 VI-30 
95.6 
0.95 
-45 
-605 
-1 -1 
E 24 I-1 III-17 
IV-1 
IV-2 
V-4 VI-37 
97.8 
0.98 
-45 
-605 
2 -2 
C 1 -- III-17 
IV-1 
IV-2 
V-4 VI-2 
96.0 
0.99 
-45 
-610 
82 -26 
C 2 -- III-7 
IV-1 
IV-2 
V-4 VI-2 
97.0 
0.95 
-46 
-608 
55 -19 
C 3 -- III-17 
IV-3 
IV-4 
V-4 VI-2 
95.5 
1.03 
-45 
-605 
59 -28 
C 4 -- III-17 
IV-1 
IV-2 
V-2 VI-2 
97.4 
1.03 
-44 
-609 
76 -16 
C 5 -- III-17 
IV-1 
IV-2 
V-4 VI-30 
95.2 
1.01 
-45 
-605 
93 -18 
__________________________________________________________________________ 
As Table 2 clearly indicates, the comparative photoconductors (C1 through 
C5) which do not contain any furan derivative or thiophene derivative in 
their charge transport layers exhibit much larger potential changes after 
the repeated printings as compared with the photoconductors of the ninth 
through twenty fourth embodiments (E9 through E24). That is, the 
comparative photoconductors do not exhibit excellent electrophotographic 
properties. If the ninth embodiment (E9) is compared with the seventeenth 
and eighteenth embodiments (E17 and E18), we see that stable 
electrophotographic properties are obtained as far as any one of the furan 
derivatives or thiophene derivatives is contained in the charge transport 
layer. 
Since the favorable effect of the furan derivatives or thiophene 
derivatives is apparent in the embodiments where the other components were 
changed, it is apparent that the present invention can be used in many 
different constituent configurations. It is seen that in the eighteenth 
and twentieth embodiments (E18 and E20) in which the charge transport 
agents are changed, in the twenty first and twenty second embodiments (E21 
and E22) in which the resin binder for the charge transport layer is 
changed, as well as in the twenty third and twenty fourth embodiments (E23 
and E24) in which the antioxidant is changed, the furan derivatives and 
the thiophene derivatives of the invention are applicable to various 
compositions for the electrophotographic photoconductor. 
By containing anyone of the furan derivatives or thiophene derivatives in 
the charge transport layer, the photoconductors for the printers, digital 
copying machines and facsimiles which contain anyone of the metal free 
phthalocyanine and titanyl phthalocyanine (III-1) through (III-6) exhibits 
the similar effects as those of the photoconductors of the foregoing 
embodiments which contain the azo compound for use in the analog copying 
machines. 
By containing anyone of the furan derivatives or thiophene derivatives in 
the charge transport layer, the photoconductors, which employ the corotron 
method, which employ charging brush method, which employ charging roller 
method and which employ the single-component development method, for 
various analog copying machines, digital copying machines, printers and 
facsimiles exhibit excellent stability against repeated use similarly as 
the photoconductors of the foregoing embodiments (E9 through E24) which 
employ the scrotron method and two-components development method do. 
By containing at least one of the furan derivatives and thiophene 
derivatives described by the general formulas (I) and (II) as the charge 
transport agent in the photoconductive layer according to the invention, a 
highly sensitive electrophotographic photoconductor, that is stabile 
enough to endure repeated continuous use for a long time in practical 
electrophotographic processes, is obtained. 
According to the present invention, a highly sensitive electrophotographic 
photoconductor that exhibits excellent electrical properties is obtained. 
By selecting an appropriate charge generating agent from, e.g., the 
phthalocyanine compounds, squalium compounds and some kinds of bisazo 
compound corresponding to the wavelength of the exposure light, the 
photoconductor of the invention is applicable to various copying machines 
and semiconductor laser printers. The durability of the photoconductor of 
the invention is improved, if necessary, by covering the photoconductor 
surface with a cover layer. 
Having described preferred embodiments of the invention with reference to 
the accompanying drawings, it is to be understood that the invention is 
not limited to those precise embodiments, and that various changes and 
modifications may be effected therein by one skilled in the art without 
departing from the scope or spirit of the invention as defined in the 
appended claims. 
Although only a single or few exemplary embodiments of this invention have 
been described in detail above, those skilled in the art will readily 
appreciate that many modifications are possible in the exemplary 
embodiment (s) without materially departing from the novel teachings and 
advantages of this invention. Accordingly, all such modifications are 
intended to be included within the scope of this invention as defined in 
the following claims, In the claims, means-plus-function clauses are 
intended to cover the structures described herein as performing the 
recited function and not only structural equivalents but also equivalent 
structures, This although a nail and screw may not be structural 
equivalents in that a nail relies entirely on friction between a wooden 
part and a cylindrical surface whereas a screw's helical surface 
positively engages the wooden part in the environment of fastening wooden 
parts, a nail and a screw may be equivalent structures.