Stock material or miscellaneous articles – Composite – Of metal
Reexamination Certificate
1999-06-09
2001-05-01
Turner, Archene (Department: 1775)
Stock material or miscellaneous articles
Composite
Of metal
C148S276000, C148S277000, C148S415000, C148S437000, C148S440000, C148S523000, C148S538000, C148S549000, C427S126100, C427S126300, C427S318000, C427S402000, C427S419100, C427S419200, C428S469000, C428S699000, C428S701000
Reexamination Certificate
active
06224987
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a conductive substrate for an electrophotographic photoconductor. More specifically, the present invention relates to a conductive substrate for an electrophotographic photoconductor having an aluminum oxide film on its surface. The present invention further relates to a manufacturing method of a conductive substrate for an electrophotographic photoconductor.
Electrophotography has developed in the field of the photostatic copiers. Recently, electrophotography has been applied to laser printing and the like. Since electrophotography is far superior than conventional impact printing in image quality, speed, and stillness, it has come to be employed widely in many devices. The conventional photoconductor installed in these devices is made of a conductive substrate having a photoconductive layer formed thereon.
The conventional conductive substrate consists of a conductive base having an undercoating layer formed thereon. Aluminum is widely used for the conductive base. Organic substances are widely used for the photoconductive layer.
The undercoating layer is formed from coating a layer of plastic, such as polyamide, onto the conductive substrate. In the alternative, the undercoating layer is formed by anodizing an oxide film onto the conductive substrate. The latter is widely used in photoconductors of high reliability, since oxide films are advantageous under environments of high temperature and high humidity. A conductive base soaked in an electrolytic solution is anodized. An oxide film is then formed on the conductive base.
Generally, the film thickness of the oxide film formed on the conductive base is ruled by the current density and the passing duration of the current, so long as the anodic current concentration is not exceeded.
Recent anodizing methods of aluminum include adjusting the configuration and spacing of an opposing electrode. Further methods devise a wave form of the current which makes the electrolytic solution foam, improving the circulation of the electrolytic solution. Such a method enables uniform distribution of the current over the entire surface of the aluminum base anode. The uniform distribution of current controls the thickness deviation of the oxide film within the range of ±1 &mgr;m. This limit in the thickness deviation creates a photoconductor having excellent printing quality.
Referring to
FIG. 2
, a surface of a conductive aluminum base
2
a
of a conventional electrophotographic photoconductor is anodized to form an aluminum oxide film
3
. Conductive substrate
1
a
for a photoconductor includes conductive aluminum base
2
a
and aluminum oxide film
3
.
A charge generation layer
4
a
and a charge transport layer
4
b
are successively formed on a surface of conductive substrate
1
a
to give a photoconductive layer
4
. Charge generation layer
4
a
absorbs light and generates free charges. Charge transport layer
4
b
receives and transports these free charges.
A semiconductor laser light having a wave length of 780 nm is widely used as a light source for a printer.
Referring to
FIG. 3
, the above-mentioned light, having a wavelength of 780 nm, is irradiated on a conventional electrophotographic photoconductor. Conductive substrate
1
a
has aluminum base
2
a
and aluminum oxide film
3
. Photoconductive layer
4
has charge generation layer
4
a
and charge transport layer
4
b
on conductive substrate
1
a.
A part of the semiconductor laser light, having a wave length of 780 nm, incident to a photoconductor indicated by an arrow L, reaches aluminum oxide film
3
without being absorbed by charge generation layer
4
a
. The light partially penetrates aluminum oxide film
3
. The penetrated light is reflected at the boundary of aluminum base
2
a
and aluminum oxide film
3
(arrow A). A portion of the light does not penetrate aluminum oxide film
3
. This portion is reflected at the boundary of charge generation layer
4
a
and aluminum oxide film
3
(arrow B).
Reflected lights A and B have the same single wavelength and are coherent. Light B interferes with light A in photoconductive layer
4
, resulting in the generation of interference fringes due to thickness variations. These interference fringes cause irregular printing density.
Japanese Laid-open Patent Publication No.6-317921 and Japanese Laid-open Patent Publication No.7-301935 disclose means to prevent irregular printing density by controlling the generation of interference fringes. These reports propose to anodize aluminum using a current of changing wave form, allowing the light to scatter in the oxide film.
When various improved manufacturing methods, such as those mentioned in Japanese Laid-open Patent Publication No.6-317921 and Japanese Laid-open Patent Publication No.7-301935, are used to obtain an uniform current density, there is obtained an aluminum oxide film with small thickness deviations. However, when semiconductor laser light is irradiated onto the photoconductor, interference fringes are generated due to small thickness variations by an interference action as described in FIG.
3
.
On the other hand, an aluminum oxide film exhibiting the above-mentioned effect of light scattering in the oxide film results in increased thickness deviation. This increase in thickness deviation leads to photoconductors having variations in their characteristics.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a conductive substrate for an electrophotographic photoconductors which overcomes the foregoing problems.
It is a further object of the present invention to provide a method of manufacturing a conductive substrate for an electrophotographic photoconductors which overcomes the foregoing problems.
It is another object of the present invention to provide a conductive substrate for an electrophotographic photoconductor having an aluminum oxide film of minimum thickness deviation and an aluminum base which prevents the generation of interference fringes when semiconductor laser light is irradiated onto the electrophotographic photoconductor.
It is yet another object of the present invention to provide a method of manufacturing a conductive substrate for an electrophotographic photoconductor having an aluminum oxide film of minimum thickness deviation and an aluminum base which prevents the generation of interference fringes when semiconductor laser light is irradiated onto the electrophotographic photoconductor.
It is still a further object of the present invention to provide an electrophotographic photoconductor having a conductive substrate with an aluminum oxide film of minimum thickness deviation and an aluminum base which prevents the generation of interference fringes when semiconductor laser light is irradiated onto the electrophotographic photoconductor.
Briefly stated, the present invention provides a conductive substrate of an electrophotographic photoconductor having magnesium silicide precipitated therein as an impurity compound. The conductive substrate has an aluminum oxide film of minimum thickness deviation, and an aluminum base which exhibits a light scattering effect. An electrophotographic photoconductor using such a conductive substrate suppresses interference fringes caused by the interference action of a semiconductor laser light. Furthermore, irregular printing density and the formation of black spots is eliminated. A method for making such a conductive substrate includes annealing an aluminum base doped with silicon and magnesium to precipitate out Ms
2
Si, followed by anodizing a surface of the aluminum base to form an aluminum oxide film.
According to an embodiment of the present invention, there is provided a conductive substrate for an electrophotographic photoconductor comprising: an aluminum base; an aluminum oxide film on the aluminum base; and the aluminum base having magnesium silicide, Mg
2
Si, precipitated therein.
According to a method of the present in vention, there is provided a method of making a conductive substrate for an ele
Fuji Electric & Co., Ltd.
Morrison Law Firm
Turner Archene
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