The present invention is directed to an electrophotographic photoreceptor which is smooth without orange peel, inhibits the rise of a residual potential and the drop of a charged potential, and is excellent in stability even when it is repeatedly used. The photoreceptor comprises a charge generation material, a charge transport material, a polyarylate having a polymerization degree of 10 to 5,000, a polycarbonate having a polymerization degree of 10 to 5,000, and a polydimethylsiloxane having a polymerization degree of 0 to 2,000.

BACKGROUND OF THE INVENTION 
(i) Field of the Invention 
The present invention relates to an electrophotographic photoreceptor 
having an excellent surface smoothness for use in various printing 
machines and copying machines. 
(ii) Description of the Related Art 
Electrophotographic photoreceptors which have now been put to practical use 
can be classified into an inorganic photoreceptor using an inorganic 
material and an organic photoreceptor using an organic material. Typical 
examples of the inorganic photoreceptor include a selenium-based 
photoreceptor comprising amorphous selenium (a-Se) or amorphous selenium 
arsenic (a-As.sub.2 Se.sub.3), a photoreceptor obtained by dispersing a 
dyestuffsensitized zinc oxide (ZnO) or cadmium sulfide (CdS) in a binder 
resin, and a photoreceptor using amorphous silicon (a-Si). 
However, among the above-mentioned inorganic photoreceptors, the 
selenium-based photoreceptor and the photoreceptor using cadmium sulfide 
are poor in heat resistance and storage stability. In addition, these 
photoreceptors contain materials which are harmful to humans, and so they 
cannot simply be discarded from the viewpoint of an environmental 
protection and must be collected under regulations. Furthermore, the 
above-mentioned zinc oxide-dispersed photoreceptor has a poor sensitivity 
and a low durability, and for this reason, it has scarcely been used 
nowadays. The above-mentioned amorphous silicon-based photoreceptor has 
features such as a high sensitivity and a high durability, but owing to 
its complex manufacturing process, it has a drawback such as the 
occurrence of image failure. 
On the other hand, typical examples of the organic photoreceptor include a 
photoreceptor using charge transfer complexes of 
2,4,7-trinitro-9-fluorenone (TNF) and polyvinylcarbazole (PVK), and 
double-layered photoconductive structures having a charge generation layer 
containing a charge generation material for generating a charge carrier at 
the time of light irradiation and a charge transport layer containing a 
charge transport material for receiving and transporting the charge 
carrier generated in the charge generation layer. The organic materials 
are more present than the inorganic materials, and the organic materials 
most suitable for the photoreceptor can be selected from a large number of 
the organic materials, whereby the photoreceptors having the excellent 
storage stability and no poison can be prepared at a low cost. In recent 
years, the organic photoreceptors are considered to be most important 
since durability thereof has been improved. 
For the above-mentioned PVK-TNF charge transfer complex-based organic 
photoreceptor, various improvements have been made, but a sufficient 
sensitivity has not been attained so far. On the other hand, the 
above-mentioned function-separated type organic photoreceptors have a 
relatively excellent sensitivity, and so they occupy most of the organic 
photoreceptors which have now been put to practical use. 
Known examples of such a function-separated type organic photoreceptors 
include a photoreceptor comprising a charge generation layer formed by 
applying an organic amine solution of chlorodiane blue and a charge 
transport layer containing a hydrazone compound (Japanese Patent 
Publication Sho 55 No. 42380), a photoreceptor comprising a charge 
generation layer containing a disazo compound and a charge transport layer 
containing a hydrazone compound (Japanese Patent Application Laid-open Sho 
59 No. 214035), and a photoreceptor comprising a charge generation layer 
containing an azulenium salt compound and a charge transport layer 
containing a hydrazone compound (Japanese Patent Application Laid-open Sho 
59 No. 53850). In addition, there has also been suggested a photoreceptor 
in which an anthanthrone or a quinone compound which is a kind of pigment 
is used as a charge generation material (U.S. Pat. No. 3877935). 
Each of these organic photoreceptors can be prepared by forming a 
photoconductive layer on a sheet-like or a drum-like conductive support. 
As a method of forming the photoconductive layer on the sheet-like 
conductive support, there is known a method using a Baker applicator or a 
bar coater. For the sake of the drum-like support, there are known a spray 
method, a vertical ring method and an immersion coating method, and among 
these methods, the immersion coating method is usually employed, because a 
device for use in this method is simple. In these methods, the formation 
of the photoconductive layer on the conductive support is carried out by 
applying a coating liquid for the formation of the photoconductive layer 
onto the conductive support to form a coating film, and then drying this 
coating film. However, in this formation process, a solvent contained in 
the coating film is vaporized by the drying, and at this time, an eddy 
convection is generated in the coating film, so that the surface of the 
dried coating film becomes uneven and smoothness is lost. This phenomenon 
is usually called "orange peel". 
Heretofore, in order to inhibit the generation of this orange peel, there 
is known a method in which a solvent having a low vaporization speed is 
used. However, if this method is particularly used for the drum-like 
conductive support, the coating film drops during the drying, so that 
thickness unevenness occurs between top and bottom surfaces of the 
support. In addition, much time is taken for the drying and productivity 
also lowers, and for these reasons, the method is not practical. In 
consequence, this method is unsuitable for the prevention of the orange 
peel. 
In the field of coating materials, a polysiloxane (the so-called silicone 
oil) is added to a coating material in order to obtain the smoothness on 
the surface of a coating film. In addition, it is also known that the 
silicone oil is effective to prevent silking and cratering. Thus, also in 
the preparation of the electrophotographic photoreceptor, it has been 
tried to add this silicone oil to the coating solution for the formation 
of the photoconductive layer, and it has been found that the silicone oil 
is effective to prevent the orange peel (Japanese Patent Publication Sho 
49 No. 15220 and Japanese Patent Application Laid-open Sho 55 No. 140849, 
Sho 55 No. 5050, Sho 57 No. 212453 and Hei 4 No. 199154). However, these 
disclosed techniques simultaneously lead to the rise of a residual 
potential and inconveniently lowers the characteristics of the 
photosensitive material. 
Japanese Patent Application Laid-open Hei 1 No. 234854 discloses an 
electrophotographic photoreceptor which can be obtained by applying a 
dispersion comprising a 4,10-dibromoanthanthrone pigment, a polycarbonate 
and dichloroethane onto a resin intermediate layer to form a charge 
generation layer, and then further applying there-onto a coating solution 
comprising the polycarbonate, methylphenylsilicone and 1,2-dichloroethane 
to form a charge transport layer. The sensitivity of this photoreceptor 
scarcely deteriorates, but it has a problem that the residual potential 
largely rises. In consequence, the disclosed photoreceptor is not 
considered to be satisfactory. 
Additionally, in order to obtain the electrophotographic photoreceptor 
having an excellent surface smoothness without impairing the 
characteristics of the photoreceptor, it has also be tried that a specific 
binder resin is combined with a specific polysiloxane to form a 
photoconductive layer (Japanese Patent Application Laid-open Hei 6 No. 
83080 and Hei 6 No. 89038). 
SUMMARY OF THE INVENTION 
Under such circumstances, an object of the present invention is to provide 
an electrophotographic photoreceptor which is excellent in surface 
smoothness and in which the characteristics of the photoreceptor do not 
deteriorate even when it is repeatedly used. 
A first aspect of the present invention is directed to an 
electrophotographic photoreceptor comprising a conductive support and a 
photoconductive layer laminated on the conductive support wherein said 
photoconductive layer contains a charge generation material, a charge 
transport material, a polyarylate represented by the formula (I) 
##STR1## 
wherein l represents a polymerization degree of 10 to 5,000, polycarbonate 
represented by the formula (II) 
##STR2## 
wherein m represents a polymerization degree of 10 to 5,000, and a 
polydimethylsiloxane represented by the formula (III) 
##STR3## 
wherein n represents a polymerization degree of 0 to 2,000. 
A second aspect of the present invention is directed to an 
electrophotographic photoreceptor comprising a conductive support, and a 
charge generation layer and a charge transport layer laminated on the 
conductive support wherein said charge transport layer contains a 
polyarylate represented by the formula (I) 
##STR4## 
wherein l represents a polymerization degree of 10 to 5,000, a 
polycarbonate represented by the formula (II) 
##STR5## 
wherein m represents a polymerization degree of 10 to 5,000, and a 
polydimethylsiloxane represented by the formula (III) 
##STR6## 
wherein n represents a polymerization degree of 0 to 2,000. 
Further advantages and features of the present invention as well as scope, 
properties and utilization of the present invention will be apparent from 
the detailed description of suitable embodiments of the present invention 
given hereinafter.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A photoreceptor of the present invention can be basically prepared by the 
following procedure, but this procedure may be partially different in 
compliance with the undermentioned constitution of the photoreceptor. That 
is to say, the photoreceptor can be prepared by dissolving or dispersing a 
charge generation material and a charge transport material which are 
photoconductive materials, a polyarylate represented by the formula (I), a 
polycarbonate represented by the formula (II) and a polydimethylsiloxane 
represented by the formula (III) in an organic solvent to form a coating 
solution, applying this coating solution onto a conductive support, and 
then drying the same to form a photoconductive layer. The 
electrophotographic photoreceptor of the present invention will be 
schematically described with reference to FIGS. 1 to 3. 
FIG. 1 shows double-layered photoconductive structures in which a 
photoconductive layer 4 comprising the two layers of a charge generation 
layer 2 and a charge transport layer 3 is formed on a conductive support 
1. 
FIG. 2 shows a photoreceptor in which an undercoat layer 5 is formed 
between the conductive support 1 and the photoconductive layer 4, and this 
undercoat layer 5 is provided for the sake of the improvement of coating 
properties, the improvement of the smoothness of the support, protection 
from mechanical damage, and the stabilization of electrical properties. 
FIG. 3 shows a single layer type photoreceptor in which a charge generation 
material 6 is dispersed in the charge transport layer 3 to form the 
photoconductive layer 4 on the conductive support 1. 
The conductive support in the photoreceptor of the present invention 
exemplified in FIGS. 1 to 3 must be conductive in itself, and examples of 
the conductive support include conductive metals such as aluminum, 
aluminum alloys, copper, zinc, stainless steel, nickel and titanium; a 
plastic and a paper on which a conductive metal film of aluminum, gold, 
silver, copper, zinc, nickel, titanium, indium oxide, tin oxide or the 
like is vapor-deposited; a plastic and a paper containing conductive 
particles; and a plastic containing a conductive polymer. The support can 
take a shape of a drum, a sheet, a seamless belt or the like. 
Next, the photoconductive layer which is formed on the above-mentioned 
conductive support will be described with regard to the constitutions of 
the photoconductive layer in FIGS. 1 to 3. 
With regard to the double-layered photoconductive structures shown in FIG. 
1, a charge generation material is contained in the charge generation 
layer of the photoconductive layer. Examples of the usable charge 
generation material include inorganic photoconductive materials such as 
selenium, its alloys, arsenic-selenium, cadmium sulfide, zinc oxide and 
amorphous silicon; organic pigments such as phthalocyanines, azo 
compounds, quinacridones, polycyclic quinones and perylenes; and organic 
dyes such as thiapyrylium salts and squarylium salts. The charge 
generation material has an absorption in a region of from visible ray to 
near infrared ray, it absorbs light to generate a carrier, and it is also 
durable. Among these charge generation materials, the above-mentioned 
organic pigments are preferable, because the formation of the 
photoreceptor is easy therefrom and a material having various optional 
absorption wavelengthes can be selected therefrom. To this charge 
generation layer, a chemical sensitizer or an optical sensitizer can be 
added. Examples of the chemical sensitizer include electron-acceptable 
materials, for example, cyano compounds such as tetracyanoethylene, 
7,7,8,8-tetracyanoquinodimethane; quiones such as anthraquinone and 
p-benzoquinone; nitro compounds such as 2,4,7-trinitrofluorenone and 
2,4,5,7-tetranitrofluorenone. Examples of the optical sensitizer include 
dyestuffs such as xanthene dyestuffs, thiazine dyestuffs and 
triphenylmethane dyestuffs. 
As a method for forming the charge generation layer, there can be used a 
gaseous phase deposition method such as a vacuum deposition method, 
sputtering or a chemical vapor deposition method (CVD). Alternatively, the 
charge generation material is dissolved in a solvent to form a coating 
solution, or the charge generation material is milled and dispersed in a 
solvent by means of a ball mill, a sand grinder, a paint shaker or an 
ultrasonic dispersing machine, and if necessary, a binder resin is added 
thereto to form a coating solution. The thus formed coating solution may 
be applied onto the sheet-like support by a Baker applicator, a bar 
coater, casting or spin coat, or alternatively the coating solution may be 
applied onto the drum-like support by a spray method, a vertical ring 
method or an immersion coating method to form the change generation layer. 
Examples of the binder resin which can be added, if necessary, for the 
formation of the charge generation layer include a polyarylate, a 
polyvinyl butyral, a polycarbonate, a polyester, a polystyrene, a 
polymethyl methacrylate, a polyvinyl chloride, a phenoxy resin, an epoxy 
resin and a silicone resin. 
Examples of the above-mentioned solvent include ketones such as acetone, 
methyl ethyl ketone and cyclohexanone; esters such as ethyl acetate and 
butyl acetate; ethers such as tetrahydrofuran and dioxane; aromatic 
hydrocarbons such as benzene, toluene and xylene; and aprotic polar 
solvents such as N,N-dimethylformamide and dimethyl sulfoxide. 
The thickness of the charge generation layer is in the range of 0.05 to 5 
.mu.m, preferably 0.08 to 1 .mu.m. If the thickness of the charge 
generation layer is less than 0.05 .mu.m, sensitivity is poor, and if it 
is more than 5 .mu.m, charging properties deteriorate. 
In the charge transport layer which is laminated on the charge generation 
layer, a charge transport material is contained. Examples of the charge 
transport material include high-molecular compounds such as 
polyvinylcarbazole and polysilane; and low-molecular compounds such as 
hydrazone compounds, pyrazoline compounds, oxadiazole compounds, stilbene 
compounds, triphenylmethane compounds, triphenylamine compounds, styryl 
compounds and enamine compounds. These compounds are preferable as the 
charge transport material, because they have no absorption in a region of 
from visible ray to near infrared ray, possess a high carrier mobility, 
and are durable. 
The charge transport layer can be formed as follows: The above-mentioned 
charge transport material is first dissolved in a solvent, and the 
polyarylate of the formula (I), the polycarbonate of the formula (II) and 
the polydimethylsiloxane of the formula (III) are then added to the 
solution to form a coating solution. Next, this coating solution may be 
applied onto the sheet-like support by means of the Baker applicator, the 
bar coater, the casting or the spin coat, or alternatively the coating 
solution may be applied onto the drum-like support by the spray method, 
the vertical ring method or the immersion coating method to form the 
charge transport layer on the change generation layer. 
The molecular weight of the polydimethylsiloxane is preferably in the range 
of 200 to 10,000, more preferably 1,000 to 10,000. The amount of the 
polydimethylsiloxane to be added is preferably in the range of 0.015 or 
more to less than 2% by weight, more preferably 0.02 to 1% by weight based 
on the total weight of the binder resin. If the amount of the 
polydimethylsiloxane is less than 0.015% by weight based on the total 
weight of the binder resin, any orange peel prevention effect cannot be 
exerted, and if it is 2% by weight or more based on the total weight of 
the binder resin, the rise of the residual potential increases. 
A ratio of the polyarylate to be mixed is suitably 10% by weight or more 
based on the total weight of the binder resin. If the amount of the 
polyarylate to be added is less than 10% by weight based on the total 
weight of the binder resin, the rise of the residual potential increases. 
Furthermore, a ratio of the polycarbonate to be mixed is suitably 10% by 
weight or more based on the total weight of the binder resin. If the 
amount of the polycarbonate to be added is less than 10% by weight based 
on the total weight of the binder resin, the drop of the charging 
properties increases. 
With regard to the binder resin for use in the formation of the charge 
transport layer, there may be added a polyester, a polystyrene, a 
polymethyl methacrylate, a polyvinyl chloride, a phenoxy resin, an epoxy 
resin or a silicone resin to the mixture of the above-mentioned 
polyarylate and polycarbonate. 
Examples of the usable solvent include halogen solvents such as 
dichloromethane and 1,2-dichloroethane; ketones such as acetone, methyl 
ethyl ketone and cyclohexanone; esters such as ethyl acetate and butyl 
acetate; ethers such as tetrahydrofuran and dioxane; aromatic hydrocarbons 
such as benzene, toluene and xylene; and aprotic polar solvents such as 
N,N-dimethylformamide and dimethyl sulfoxide. If the solvent having a low 
vaporization speed is used, sag or the like occurs, and hence it is 
desirable to use a solvent such as dichloromethane, acetone or 
tetrahydrofuran. 
The thickness of the charge transport layer is in the range of 5 to 50 
.mu.m, preferably 10 to 40 .mu.m. If the thickness of the charge transport 
layer is less than 5 .mu.m, the charging properties become poor, and if it 
is more than 50 .mu.m, it is difficult to form a uniform film. 
To the charge generation layer or the charge transport layer, an 
antioxidant may be added as an additive. Examples of the antioxidant 
include vitamin E, hydroquinones, hindered amines, hindered phenols, 
p-phenylenediamines, arylalkanes, derivatives thereof, organic sulfur 
compounds and organic phosphorus compounds. 
The undercoat layer shown in FIG. 2 is provided for the sake of the 
improvement of coating properties, the improvement of the smoothness of 
the support, protection from mechanical damage, and the stabilization of 
electrical properties, and examples of the undercoat layer include 
polyvinyl alcohol, polyvinyl butyral, casein and N-methoxymethylated 
nylons. The thickness of the undercoat layer is preferably in the range of 
0.2 to 10 .mu.m. If the thickness of the undercoat layer is less than 0.2 
.mu.m, the merit of the formation of the undercoat layer cannot be 
exerted, and if it is more than 10 .mu.m, sensitivity is poor. 
The single layer type photoreceptor shown in FIG. 3 comprises the 
conductive support and the photoconductive layer on the conductive 
support, and this photoconductive layer is formed by dispersing the 
above-mentioned charge generation material and charge transport material 
in the charge transport layer. 
This single layer type photoreceptor can be prepared by dissolving or 
dispersing the above-mentioned charge generation material and charge 
transport material as well as the binder resin containing the resins 
represented by the formulae (I), (II) and (III) in the above-mentioned 
solvent to form a coating solution, applying this coating solution onto 
the conductive support by the above-mentioned formation method, and then 
drying the same. 
The constitutions of the electrophotographic photoreceptor of the present 
invention are not limited to the photoreceptors shown in FIGS. 1 to 3, and 
the present invention covers various other similar constitutions. For 
example, a surface protective layer may be further formed on the surface 
of the photoconductive layer. 
When the three components of the polyarylate of the formula (I), the 
polycarbonate of the formula (II) and the polydimethylsiloxane of the 
formula (III) are contained in the photoconductive layer formed on the 
conductive support, there can be obtained an electrophotographic 
photoreceptor which has no orange peel and a smooth surface, can prevent 
the rise of the residual potential and the drop of the charged potential, 
and has so an excellent stability as to be repeatedly usable. 
EXAMPLES 
Next, a photoreceptor of the present invention will be described in more 
detail with reference to examples and comparative examples, but the scope 
of the present invention should not be limited to these examples at all. 
For the photoreceptors obtained in the examples and the comparative 
examples, the following evaluations were made. 
Measurement of sensitivity: 
The sensitivity was measured by a drum evaluation device which was made by 
the present inventors. That is to say, the sensitivity was evaluated by a 
reciprocal number of a light energy required until a charged potential had 
been 1/2, when irradiation was carried out with a light having 550 nm and 
10 .mu.W/cm.sup.2 separated by an interference filter. 
Measurement of charged potential (V.sub.0) and residual potential 
(V.sub.r): 
An obtained electrophotographic photoreceptor was put on a commercially 
available copying machine (SF8260; made by Sharp Corporation), and after 
the confirmation of an image, the charged potentials (V.sub.0) and the 
residual potentials (V.sub.r) were measured at an initial stage and after 
use of 10,000 times as a potential fluctuation at the time of the repeated 
use. 
Measurement of orange peel: 
The surface of the photoconductive layer was visually evaluated, and the 
layer having no orange peel and the layer having the orange peel were 
evaluated to be o and x, respectively. 
In this connection, the sensitivity and the charged potential in Examples 
11, 12 and 14 were measured in slightly different manners, and so the 
measurement procedures will be supplementally described in the examples. 
A dimethyl silicone oil (SH200, 50 cs; made by Toray Silicone Co., Ltd.) 
which can be used in the examples corresponds to polydimethylsiloxane 
represented by the formula (III). 
EXAMPLE 1 
(Double-layered photoconductive structures) 
2 parts by weight of a polycyclic quinone pigment represented by the 
formula 
##STR7## 
as a charge generation material and 1 part by weight of a phenoxy resin 
(PKHH; made by Union Carbide Corp.) were dispersed in 97 parts by weight 
of 1,4-dioxane for 12 hours by a ball mill dispersing machine to prepare a 
dispersion. 
A tank was filled with this dispersion, and a cylindrical aluminum support 
(aluminum drum) having a diameter of 80 mm and a length of 340 mm was 
immersed in the tank. Afterward, the support was pulled up, and the thus 
applied layer on the support was then dried for 1 hour to form a charge 
generation layer having a thickness of 1 .mu.m. 
On the other hand, 100 parts by weight of a hydrazone compound represented 
by the formula 
##STR8## 
as a charge transport material, 50 parts by weight of a polyarylate 
(U-100; made by Unitika Ltd.) and 50 parts by weight of a polycarbonate 
(S-2000; made by Mitsubishi Gas Chemical Company, Inc.) as binder resins, 
and 0.02 part by weight of a dimethyl silicone oil (SH200, 50 cs; made by 
Toray Silicone Co., Ltd.) were dissolved in 800 parts by weight of 
dichloromethane to prepare a coating solution for the formation of a 
charge transport layer. 
Next, by immersion, this coating solution was applied onto the charge 
generation layer formed on the support, and then dried at 80.degree. C. 
for 1 hour to form the charge transport layer having a thickness of 20 
.mu.m, whereby such double-layered photoconductive structures as shown in 
FIG. 1 were prepared. 
For the thus obtained photoreceptor, the above-mentioned evaluations were 
made. The results are shown in Table 1. 
EXAMPLES 2 to 9 
(Double-layered photoconductive structures) 
The same procedure as in Example 1 was repeated except that a ratio of a 
polyarylate to a polycarbonate and the amount of a dimethyl silicone oil 
were changed as in Table 1, to prepare such a photoreceptor as shown in 
FIG. 1, and evaluations were then made. The results are shown in Table 1. 
Comparative Example 1 
(Double-layered photoconductive structures containing no dimethyl silicone 
oil) 
The same procedure as in Example 1 was repeated except that a dimethyl 
silicone oil was not used, to prepare such a photoreceptor as shown in 
FIG. 1, and its characteristics were then evaluated. The results are shown 
in Table 1. 
With regard to the photoreceptor, the rise of a residual potential was 
scarcely observed, but orange peel was seen all over the surface of a 
photoconductive layer and an obtained image was also in a rough state. 
Comparative Example 2 
(Double-layered photoconductive structures containing no polyarylate resin) 
The same procedure as in Example 1 was repeated except that a polyarylate 
was not used in a binder resin for a charge transport layer and 100 parts 
by weight of a polycarbonate (S-2000; made by Mitsubishi Gas Chemical 
Company, Inc.) and 0.1 part by weight of a dimethyl silicone oil (SH200, 
50 cs; made by Toray Silicone Co., Ltd.) were used, to prepare such a 
photoreceptor as shown in FIG. 1, and its characteristics were then 
evaluated. The results are shown in Table 1. With regard to the 
photoreceptor, no orange peel was observed on the surface of a 
photoconductive layer, and a clear image was obtained, but a residual 
potential rose when the photoreceptor was repeatedly used. 
Comparative Example 3 
(Double-layered photoconductive structures containing no polycarbonate 
resin) 
The same procedure as in Example 1 was repeated except that a polycarbonate 
was not used in a binder resin for a charge transport layer and 100 parts 
by weight of a polyarylate (U-100; made by Unitika Ltd.) and 0.1 part by 
weight of a dimethyl silicone oil (SH200, 50 cs; made by Toray Silicone 
Co., Ltd.) were used, to prepare such a photoreceptor as shown in FIG. 1, 
and its characteristics were then evaluated. The results are shown in 
Table 1. With regard to the photoreceptor, no orange peel was observed on 
the surface of a photoconductive layer, and a clear image was obtained, 
but a charged potential dropped when the photoreceptor was repeatedly 
used. 
EXAMPLE 10 
(Double-layered photoconductive structures) 
4 parts by weight of a chlorodiane blue represented by the formula 
##STR9## 
as a charge generation material was dissolved in 257 parts by weight of 
ethylenediamine, and the solution was then stirred for 45 minutes. Next, 
247 parts by weight of n-butylamine was added thereto, followed by 
stirring for 45 minutes to prepare a coating solution. 
A tank was filled with this dispersion, and a cylindrical aluminum support 
having a diameter of 80 mm and a length of 340 mm was then immersed in the 
tank. Afterward, the support was pulled up, and the thus applied layer on 
the support was then dried at room temperature for 1 hour to form a charge 
generation layer having a thickness of 1 .mu.m. 
On the other hand, 100 parts by weight of a hydrazone compound represented 
by the formula 
##STR10## 
as a charge transport material, 50 parts by weight of a polyarylate 
(U-100; made by Unitika Ltd.) and 50 parts by weight of a polycarbonate 
(K-1300; made by Teijin Chemicals Limited) as binder resins, and 0.05 part 
by weight of a dimethyl silicone oil (SH200, 50 cs; made by Toray Silicone 
Co., Ltd.) were dissolved in 800 parts by weight of dichloromethane to 
prepare a coating solution for the formation of a charge transport layer. 
By immersion, this coating solution was applied onto the charge generation 
layer formed on the support and then dried at 80.degree. C. for 1 hour to 
form the charge transport layer having a thickness of 20 .mu.m, whereby 
such a photoreceptor as shown in FIG. 1 was prepared. Afterward, 
evaluations were made, and the results are shown in Table 1. 
EXAMPLE 11 
(Double-layered photoconductive structures having an undercoat layer) 
6 parts by weight of a copolymer nylon (Amilan CM 8000; made by Toray 
Industries, Inc.) was dissolved in a mixed solvent of 47 parts by weight 
of methyl alcohol and 47 parts by weight of chloroform, and a tank was 
filled with this dispersion and a cylindrical aluminum support having a 
diameter of 30 mm and a length of 255 mm was immersed in the tank. 
Afterward, the support was pulled up, and the thus applied layer on the 
support was then dried at 110.degree. C. for 10 minutes to form a 
undercoat layer having a thickness of about 2 .mu.m. 
Next, 2 parts by weight of an X type non-metallic phthalocyanine 
represented by the formula 
##STR11## 
as a charge generation material, 1 part by weight of polyvinyl butyral 
(Eslec BMS; made by Sekisui Chemical Co., Ltd.) were dispersed in 97 parts 
by weight of dichloroethane by a ball mill dispersing machine for 12 hours 
to prepare a dispersion. 
A tank was filled with this dispersion, and the above-mentioned cylindrical 
aluminum support equipped with the undercoat layer was immersed in the 
tank. Afterward, the support was pulled up, and the thus applied layer on 
the support was then dried at room temperature for 1 hour to form a charge 
generation layer having a thickness of 0.2 .mu.m. 
On the other hand, 100 parts by weight of a styryl compound represented by 
the formula 
##STR12## 
as a charge transport material, 70 parts by weight of a polyarylate 
(U-100; made by Unitika Ltd.) and 30 parts by weight of a polycarbonate 
(Novalex 7025A; made by Mitsubishi Chemical Industries, Ltd.) as binder 
resins, and 0.03 part by weight of a dimethyl silicone oil (SH 200, 50 cs; 
made by Toray Silicone Co., Ltd.) were dissolved in 800 parts by weight of 
chloroform to prepare a coating solution for the formation of a charge 
transport layer. 
By immersion, this coating solution was applied onto the charge generation 
layer formed on the support and then dried at 100.degree. C. for 1 hour to 
form the charge transport layer having a thickness of 20 .mu.m, whereby 
such a photoreceptor as shown in FIG. 2 was prepared. 
The sensitivity of this photoreceptor was measured in the same manner as in 
Example 1 except that a drum evaluation device made by the present 
inventors and a light of 780 nm were used, and the photoreceptor was then 
put on a commercially available laser beam printer (JX9500; made by Sharp 
Corporation). After the confirmation of an image, charged potentials 
(V.sub.0) and residual potentials (V.sub.r) were measured at an initial 
stage and after use of 10,000 times as a potential fluctuation at the time 
of the repeated use. The results are shown in Table 1. 
EXAMPLE 12 
(A single layer type photoreceptor) 
2 parts by weight of a perylene pigment represented by the formula 
##STR13## 
as a charge generation material was dispersed in 98 parts by weight of 
1,2-dichloroethane by a paint shaker to prepare a dispersion. 
100 parts by weight of a hydrazone compound represented by the formula 
##STR14## 
as a charge transport material, 50 parts by weight of a polyarylate 
(U-100; made by Unitika Ltd.) and 50 parts by weight of a polycarbonate 
(K-1300; made by Teijin Chemicals Limited) as binder resins, and 0.03 part 
by weight of a dimethyl silicone oil (SH200, 20 cs; made by Toray Silicone 
Co., Ltd.) were dissolved in 700 parts by weight of dichloromethane, and 
the resultant solution was then added to the above-mentioned dispersion to 
prepare a coating solution for the formation of a photoconductive layer. 
By immersion, this coating solution was applied onto a cylindrical aluminum 
support having a diameter of 80 mm and a length of 340 mm, and then dried 
at 100.degree. C. for 1 hour to form a photoconductive layer having a 
thickness of 15 .mu.m, whereby such a single layer type photoreceptor as 
shown in FIG. 3 was prepared. 
The sensitivity of this photoreceptor was measured by the same drum 
evaluation device as in Example 1 made by the present inventors, and the 
photoreceptor was then put on a test machine made by remodeling a 
commercially available copying machine (SF8100; made by Sharp Corporation) 
into a device for positive charging. After the confirmation of an image, 
charged potentials (V.sub.0) and residual potentials (V.sub.r) were 
measured at an initial stage and after use of 10,000 times as a potential 
fluctuation at the time of the repeated use. The results are shown in 
Table 1. 
EXAMPLE 13 
(Double-layered photoconductive structures) 
2 parts by weight of a bisazo pigment represented by the formula 
##STR15## 
as a charge generation material and 1 part by weight of polyvinyl butyral 
(XYHL; made by Union Carbide Corp.) were dispersed in 97 parts by weight 
of cyclohexanone by a ball mill to prepare a dispersion. 
A tank was filled with this dispersion, and a cylindrical aluminum support 
having a diameter of 80 mm and a length of 340 mm was immersed in the 
tank. Afterward, the support was pulled up, and the thus applied layer on 
the support was then dried at 110.degree. C. for 10 minutes to form a 
charge generation layer having a thickness of 0.8 .mu.m. 
On the other hand, 100 parts by weight of a hydrazone compound represented 
by the formula 
##STR16## 
as a charge transport material, 40 parts by weight of a polyarylate 
(U-100; made by Unitika Ltd.), 40 parts by weight of a polycarbonate 
(C-1400; made by Teijin Chemicals Limited) and 20 parts by weight of a 
polyester resin (V290; made by Toyobo Co., Ltd.) as binder resins, and 
0.02 part by weight of a dimethyl silicone oil (SH200, 50 cs; made by 
Toray Silicone Co., Ltd.) were dissolved in 800 parts by weight of 
dichloromethane to prepare a coating solution for the formation of a 
charge transport layer. 
By immersion, this coating solution was applied onto the charge generation 
layer formed on the support, and then dried at 80.degree. C. for 1 hour to 
form the charge transport layer having a thickness of 20 .mu.m, whereby 
such a photoreceptor as shown in FIG. 1 was prepared. Afterward, 
evaluations were carried out by the same procedures as in Example 1. The 
results are shown in Table 1. 
EXAMPLE 14 
(Double-layered photoconductive structures) 
2 parts by weight of a perylene pigment represented by the formula 
##STR17## 
as a charge generation material and 1 part by weight of a phenoxy resin 
(PKHH; made by Union Carbide Corp.) were dispersed in 97 parts by weight 
of 1,4-dioxane for 12 hours by a ball mill dispersing machine to prepare a 
dispersion. 
This dispersion was applied, by the use of an applicator, onto a conductive 
support in which an aluminum layer was formed on the surface of 
polyethylene terephthalate by a vapor deposition method, and then dried at 
room temperature to form a charge generation layer having a thickness of 1 
.mu.m. 
On the other hand, 100 parts by weight of a hydrazone compound represented 
by the formula 
##STR18## 
as a charge transport material, 30 parts by weight of a polyarylate 
(U-100; made by Unitika Ltd.), 30 parts by weight of a polycarbonate 
(C-1400; made by Teijin Chemicals Limited) and 40 parts by weight of a 
polyester resin (V-290; made by Toyobo Co., Ltd.) as binder resins, and 
0.02 part by weight of a dimethyl silicone oil (SH200, 50 cs; made by 
Toray Silicone Co., Ltd.) were dissolved in 800 parts by weight of 
dichloromethane to prepare a coating solution for the formation of a 
charge transport layer. 
Next, by the use of an applicator, this coating solution was applied onto 
the charge generation layer formed on the support and then dried at 
80.degree. C. for 1 hour to form the charge transport layer having a 
thickness of 20 .mu.m, whereby such a photoreceptor as shown in FIG. 1 was 
prepared. 
This photoreceptor was stuck on a cylindrical aluminum support having a 
diameter of 80 mm and a length of 340 mm with a conductive tape, and the 
sensitivity of the photoreceptor was measured by a drum evaluation device 
made by the present inventors. Afterward, the photoreceptor was then put 
on a commercially available copying machine (SF8260; made by Sharp 
Corporation), and after the confirmation of an image, charged potentials 
(V.sub.0) and residual potentials (V.sub.r) were measured at an initial 
stage and after use of 10,000 times as a potential fluctuation at the time 
of the repeated use. The results are shown in Table 1. 
EXAMPLE 15 
(Double-layered photoconductive structures having an undercoat layer) 
8 parts by weight of titanium oxide (TTO-55(A); made by Ishihara Sangyo 
Kaisha Ltd.) and 2 parts by weight of a copolymer nylon (Amilan CM 8000; 
made by Toray Industries, Inc.) were dispersed in a mixture of 45 parts by 
weight of methyl alcohol and 45 parts by weight of chloroform for 8 hours 
by a paint shaker to prepare a coating solution for an undercoat layer. A 
tank was filled with this coating solution, and a cylindrical aluminum 
support having a diameter of 80 mm and a length of 340 mm was immersed in 
the tank. Afterward, the support was pulled up, and the thus applied layer 
on the support was then dried at 110.degree. C. for 10 minutes to form the 
undercoat layer having a thickness of 1 .mu.m. 
Next, 2 parts by weight of a bisazo pigment represented by the formula 
##STR19## 
as a charge generation material and 1 part by weight of an epoxy resin 
(Rikaresin BPO-20E; made by Shin-Nippon Rika Co., Ltd.) were dispersed in 
97 parts by weight of dimethoxyethane for 12 hours by a ball mill 
dispersing machine to prepare a dispersion. A tank was filled with this 
dispersion, and the above-mentioned cylindrical aluminum support equipped 
with the undercoat layer was immersed in the tank. Afterward, the support 
was pulled up, and the thus applied layer on the support was then dried at 
room temperature for 1 hour to form a charge generation layer having a 
thickness of 0.2 .mu.m. 
On the other hand, 70 parts by weight of a bishydrazone compound 
represented by the formula 
##STR20## 
and 30 parts by weight of a hydrazone compound represented by the formula 
##STR21## 
as charge transport materials, 40 parts by weight of a polyarylate (U-100; 
made by Unitika Ltd.), 40 parts by weight of a polycarbonate (C-1400; made 
by Teijin Chemicals Limited) and 20 parts by weight of a polyester resin 
(V-290; made by Toyobo Co., Ltd.) as binder resins, and 0.02 part by 
weight of a dimethyl silicone oil (SH200, 50 cs; made by Toray Silicone 
Co., Ltd.) were dissolved in 800 parts by weight of dichloromethane to 
prepare a coating solution for the formation of a charge transport layer. 
By immersion, this coating solution was applied onto the previously formed 
charge generation layer and then dried at 80.degree. C. for 1 hour to form 
the charge transport layer having a thickness of 20 .mu.m, whereby such a 
photoreceptor as shown in FIG. 2 was prepared. 
The surface of the obtained photoreceptor was smooth without any orange 
peel. Afterward, for the obtained photoreceptor, evaluations were carried 
out, and the results are shown in Table 1. 
EXAMPLE 16 
(Double-layered photoconductive structures having an undercoat layer) 
8 parts by weight of titanium oxide (TA-300; made by Fuji Titanium Co., 
Ltd.) and 2 parts by weight of a methoxymethylated nylon (EF30T; made by 
Teikoku Chemicals Co., Ltd.) were dispersed in a mixture of 28 parts by 
weight of methyl alcohol and 52 parts by weight of 1,2-dichloroethane for 
8 hours by a paint shaker to prepare a coating solution for an undercoat 
layer. A tank was filled with this coating solution, and a cylindrical 
aluminum support having a diameter of 80 mm and a length of 340 mm was 
immersed in the tank. Afterward, the support was pulled up, and the thus 
applied layer on the support was then dried at 110.degree. C. for 10 
minutes to form the undercoat layer having a thickness of 1.5 .mu.m. 
Next, 2 parts by weight of a bisazo pigment represented by the formula 
##STR22## 
as a charge generation material and 1 part by weight of a phenoxy resin 
(PKHJ; made by Union Carbide Corp.) were dispersed in 97 parts by weight 
of 1,4-dioxane for 5 hours by a paint shaker to prepare a dispersion. A 
tank was filled with this dispersion, and the above-mentioned cylindrical 
aluminum support equipped with the undercoat layer was immersed in the 
tank. Afterward, the support was pulled up, and the thus applied layer on 
the support was then dried at room temperature for 1 hour to form a charge 
generation layer having a thickness of 0.2 .mu.m. 
On the other hand, 90 parts by weight of a bishydrazone compound 
represented by the formula 
##STR23## 
and 10 parts by weight of a hydrazone compound represented by the formula 
##STR24## 
as charge transport materials, 30 parts by weight of a polyarylate 
(Crystalate A-801; made by Kanegafuchi Chemical Industry Co., Ltd.), 40 
parts by weight of a polycarbonate (L-1225; made by Teijin Chemicals 
Limited) and 30 parts by weight of a polyester resin (V-200; made by 
Toyobo Co., Ltd.) as binder resins, and 0.02 part by weight of a dimethyl 
silicone oil (SH200, 100 cs; made by Toray Silicone Co., Ltd.) were 
dissolved in 800 parts by weight of dichloromethane to prepare a coating 
solution for the formation of a charge transport layer. 
By immersion, this coating solution was applied onto the previously formed 
charge generation layer and then dried at 80.degree. C. for 1 hour to form 
the charge transport layer having a thickness of 20 .mu.m, whereby such a 
photoreceptor as shown in FIG. 2 was prepared. 
The surface of the obtained photoreceptor was smooth without any orange 
peel. Afterward, for the obtained photoreceptor, evaluations were carried 
out, and the results are shown in Table 1. 
EXAMPLE 17 
(Double-layered photoconductive structures having an undercoat layer) 
8 parts by weight of titanium oxide (TTO-55(A); made by Ishihara Sangyo 
Kaisha Ltd.) and 2 parts by weight of a methoxymethylated nylon (EF30T; 
made by Teikoku Chemicals Co., Ltd.) were dispersed in a mixture of 28 
parts by weight of methyl alcohol and 52 parts by weight of 
1,2-dichloroethane for 8 hours by a paint shaker to prepare a coating 
solution for an undercoat layer. A tank was filled with this coating 
solution, and a cylindrical aluminum support having a diameter of 80 mm 
and a length of 340 mm was immersed in the tank. Afterward, the support 
was pulled up, and the thus applied layer on the support was then dried at 
110.degree. C. for 10 minutes to form the undercoat layer having a 
thickness of 1 .mu.m. 
Next, 2 parts by weight of a bisazo pigment represented by the formula 
##STR25## 
as a charge generation material and 1 part by weight of a phenoxy resin 
(PKHJ; made by Union Carbide Corp.) were dispersed in 97 parts by weight 
of tetrahydrofuran for 5 hours by a paint shaker to prepare a dispersion. 
A tank was filled with this dispersion, and the above-mentioned 
cylindrical aluminum support equipped with the undercoat layer was 
immersed in the tank. Afterward, the support was pulled up, and the thus 
applied layer on the support was then dried at room temperature for 1 hour 
to form a charge generation layer having a thickness of 0.2 .mu.m. 
On the other hand, 100 parts by weight of an enamine compound represented 
by the formula 
##STR26## 
as a charge transport material, 40 parts by weight of a polyarylate 
(U-100; made by Unitika Ltd.), 40 parts by weight of a polycarbonate 
(C-1400; made by Teijin Chemicals Limited) and 20 parts by weight of a 
polyester resin (V-290; made by Toyobo Co., Ltd.) as binder resins, and 
0.02 part by weight of a dimethyl silicone oil (SH200, 50 cs; made by 
Toray Silicone Co., Ltd.) were dissolved in 800 parts by weight of 
dichloromethane to prepare a coating solution for the formation of a 
charge transport layer. 
By immersion, this coating solution was applied onto the previously formed 
charge generation layer, and then dried at 80.degree. C. for 1 hour to 
form the charge transport layer having a thickness of 20 .mu.m, whereby 
such a photoreceptor as shown in FIG. 2 was prepared. 
The surface of the obtained photoreceptor was smooth without any orange 
peel. Afterward, for the obtained photoreceptor, evaluations were carried 
out, and the results are shown in Table 1. 
EXAMPLE 18 
(Double-layered photoconductive structures having an undercoat layer) 
8 parts by weight of titanium oxide (TTO-55(A); made by Ishihara Sangyo 
Kaisha Ltd.) and 2 parts by weight of a methoxymethylated nylon (EF30T; 
made by Teikoku Chemicals Co., Ltd.) were dispersed in a mixture of 28 
parts by weight of methyl alcohol and 52 parts by weight of 
1,2-dichloroethane for 8 hours by a paint shaker to prepare a coating 
solution for an undercoat layer. A tank was filled with this coating 
solution, and a cylindrical aluminum support having a diameter of 80 mm 
and a length of 340 mm was immersed in the tank. Afterward, the support 
was pulled up, and the thus applied layer on the support was then dried at 
110.degree. C. for 10 minutes to form the undercoat layer having a 
thickness of 1.5 .mu.m. 
Next, 2 parts by weight of a bisazo pigment represented by the formula 
##STR27## 
as a charge generation material and 1 part by weight of a phenoxy resin 
(PKHH; made by Union Carbide Corp.) were dispersed in 97 parts by weight 
of 1,4-dioxane for 20 hours by a ball mill to prepare a dispersion. A tank 
was filled with this dispersion, and the above-mentioned cylindrical 
aluminum support equipped with the undercoat layer was immersed in the 
tank. Afterward, the support was pulled up, and the thus applied layer on 
the support was then dried at room temperature for 1 hour to form a charge 
generation layer having a thickness of 0.3 .mu.m. 
On the other hand, 100 parts by weight of an enamine compound represented 
by the formula 
##STR28## 
as a charge transport material, 50 parts by weight of a polyarylate 
(U-100; made by Unitika Ltd.) and 50 parts by weight of a polycarbonate 
(C-1400; made by Teijin Chemicals Limited) as binder resins, 2 parts by 
weight of vitamin E (DL-.alpha.-tocopherol) and 1 part by weight of a 
dimethyl silicone oil (SH200, 20 cs; made by Toray Silicone Co., Ltd.) 
were dissolved in 800 parts by weight of dichloromethane to prepare a 
coating solution for the formation of a charge transport layer. 
By immersion, this coating solution was applied onto the previously formed 
charge generation layer and then dried at 80.degree. C. for 1 hour to form 
the charge transport layer having a thickness of 20 .mu.m, whereby such a 
photoreceptor as shown in FIG. 2 was prepared. 
The surface of the obtained photoreceptor was smooth without any orange 
peel. Afterward, for the obtained photoreceptor, evaluations were carried 
out, and the results are shown in Table 1. 
Comparative Example 4 
(Double-layered photoconductive structures) 
The same procedure as in Example 1 was repeated except that 0.01 part by 
weight of a dimethyl silicone oil (SH200, 50 cs; made by Toray Silicone 
Co., Ltd.) was added, to prepare a sample, and its characteristics were 
then evaluated. The results are shown in Table 1. 
Orange peel was observed all over the surface of the obtained 
photoreceptor, and an obtained image was also in a rough state. The rise 
of a residual potential was scarcely observed. 
Comparative Example 5 
(Double-layered photoconductive structures) 
The same procedure as in Example 1 was repeated except that 2 parts by 
weight of a dimethyl silicone oil (SH200, 50 cs; made by Toray Silicone 
Co., Ltd.) was added, to prepare a sample, and its characteristics were 
then evaluated. The results are shown in Table 1. 
No orange peel was observed all over the surface of the obtained 
photoreceptor, and a clear image was obtained. However, a residual 
potential rose, when the photoreceptor was repeatedly used. 
As is apparent from the results shown in Table 1, the photoreceptors 
containing the three components of a polyarylate, a polycarbonate and a 
polydimethylsiloxane, i.e., the photoreceptors of Example 1 to 18 have no 
orange peel and scarcely bring about the rise of a residual potential and 
the drop of a charged potential. On the contrary, as in Comparative 
Example 1 to 5, the photoreceptors beyond the scope of the present 
invention lead to the orange peel, the rise of the residual potential and 
the drop of the charged potential. 
TABLE 1 
______________________________________ 
Kinds of Contained Resins and the Like 
Dimethyl 
Poly- Poly- Silicone 
acrylate carbonate Oil 
(pts. wt.) (pts. wt.) 
(pts. wt.) 
______________________________________ 
Example 1 
50 50 0.02 
Example 2 
30 70 0.02 
Example 3 
10 90 0.02 
Example 4 
10 90 0.10 
Example 5 
10 90 0.20 
Example 6 
70 30 0.02 
Example 7 
90 10 0.02 
Example 8 
90 10 0.10 
Example 9 
90 10 0.50 
Example 10 
50 50 0.05 
Example 11 
70 30 0.02 
Example 12 
50 50 0.03 
Example 13 
40 40 0.02 
Example 14 
30 30 0.02 
Example 15 
40 40 0.02 
Example 16 
30 40 0.02 
Example 17 
40 40 0.02 
Example 18 
50 50 1.00 
Comp. Ex. 1 
50 50 0 
Comp. Ex. 2 
0 100 0.10 
Comp. Ex. 3 
100 0 0.10 
Comp. Ex. 4 
50 50 0.01 
Comp. Ex. 5 
50 50 2.00 
______________________________________ 
Charged Residual 
Pre- Potential Potential 
vention 
Sensi- V.sub.0 (V) Vr (V) 
Of tivity At After At After 
Orange (cm.sup.2 / 
Initial 
10,000 
Initial 
10,000 
Peel .mu.J) Stage times Stage times 
______________________________________ 
Example 1 
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1.5 -710 -700 -15 -25 
Example 2 
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1.5 -720 -710 -15 -25 
Example 3 
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1.5 -730 -720 -20 -30 
Example 4 
.smallcircle. 
1.5 -730 -720 -20 -30 
Example 5 
.smallcircle. 
1.5 -730 -720 -20 -30 
Example 6 
.smallcircle. 
1.5 -710 -700 -15 -25 
Example 7 
.smallcircle. 
1.5 -700 -690 -15 -20 
Example 8 
.smallcircle. 
1.5 -700 -690 -15 -20 
Example 9 
.smallcircle. 
1.5 -700 -690 -15 -20 
Example 10 
.smallcircle. 
1.3 -710 -705 -15 -25 
Example 11 
.smallcircle. 
2.6 -700 -690 -20 -30 
Example 12 
.smallcircle. 
0.8 710 700 45 55 
Example 13 
.smallcircle. 
4.0 -710 -700 -10 -20 
Example 14 
.smallcircle. 
1.1 -710 -700 -40 -50 
Example 15 
.smallcircle. 
2.0 -700 -690 -10 -20 
Example 16 
.smallcircle. 
2.5 -720 -710 -10 -25 
Example 17 
.smallcircle. 
3.0 -720 -710 -10 -20 
Example 18 
.smallcircle. 
3.1 -720 -700 -10 -20 
Comp. Ex. 1 
x 1.5 -710 -700 -15 -25 
Comp. Ex. 2 
.smallcircle. 
1.5 -710 -760 -15 -80 
Comp. Ex. 3 
.smallcircle. 
1.5 -700 -640 -10 -15 
Comp. Ex. 4 
x 1.5 -700 -685 -10 -20 
Comp. Ex. 5 
.smallcircle. 
1.5 -700 -755 -10 -65 
______________________________________