Claims
- 1. A composite photosensitive element for use in electrophotography and capable of achieving dichromatic developement, which comprises: an electrically conductive substrate; a first photoconductive layer laminated on top of said substrate, said first photoconductive layer being substantially insensitive to red light, said first photoconductive layer being selected from the group consisting of (1) a vapor-deposited Se-As sub-layer consisting essentially of from 1 to 6% by weight of As and the balance is essentially Se, said Se-As sub-layer having a thickness of from 20 to 40 .mu.m, and a vapor-deposited Se-Te sub-layer coated directly on top of said Se-As sub-layer, said Se-Te sub-layer consisting essentially of from 4 to 12% by weight of Te and the balance is essentially Se, said Se-Te sub-layer having a thickness of from 0.5 to 5.mu.m, and (2) a vapor-deposited Se-Te-As layer consisting essentially of from 4 to 12% by weight of Te, from 1 to 4% by weight of As and the balance is essentially Se, said layer having a thickness of from 20 to 50.mu.m; a second photoconductive layer laminated on top of said first photoconductive layer, said second photoconductive layer being permeable to light and being sensitive to red light, said second photoconductive layer comprising a charge carrier generating sub-layer consisting essentially of a photoconductive azo pigment laminated on top of said first photoconductive layer, and a charge transport sub-layer laminated on top of said charge carrier generating sub-layer, said charge carrier generating sub-layer having a thickness of from 0.01 to 1.0 .mu.m and said charge transport sub-layer having a thickness of from 10 to 30 .mu.m; wherein said composite photosensitive element is subjected to a first negative electrification in the dark and then to a second, positive or alternating current electrification in the dark at a lower voltage than said first electrification whereby to charge said first photoconductive layer with a positive charge and to charge said second photoconductive layer with a negative charge, then effecting imagewise exposure of said composite photosensitive element through a dichromatic original having a black area and a red area on a white background whereby to form on said composite photosensitive element an electrostatic latent image in which the surface potential of the electrostatic latent image corresponding to the black area of the original is of opposite charge relative to the surface potential of the electrostatic latent image corresponding to the red area of the original, and then developing said electrostatic latent image by applying thereto, in succession, two toners of opposite polarity and different colors, whereby to obtain a dichromatic visible image.
- 2. A composite photosensitive element as claimed in claim 1 in which said first photoconductive layer consists of said layer (1).
- 3. A composite photosensitive element as claimed in claim 1 in which said first photoconductive layer consists of said Se-Te-As layer (2).
- 4. A composite photosensitive element as claimed in claim 1, claim 2 or claim 3, including an intermediate layer between said first photoconductive layer and said charge carrier generating sub-layer, said intermediate layer being capable of preventing the transfer of plus electric charges and of permitting the transfer of minus electric charges in the dark.
- 5. A composite photosensitive element as claimed in claim 4 in which said intermediate layer consists of three sublayers and the middle sub-layer consists essentially of an azo pigment or cyan coloring matter effective for filtering red light.
- 6. A composite photosensitive element as claimed in claim 1 in which said charge transport sub-layer consists essentially of an electron donor.
Priority Claims (2)
Number |
Date |
Country |
Kind |
56-4260 |
Jan 1981 |
JPX |
|
56-9248 |
Jan 1981 |
JPX |
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Parent Case Info
This application is a continuation of U.S. Ser. No. 337,211 filed Jan. 5, 1982, now abandoned.
US Referenced Citations (7)
Foreign Referenced Citations (1)
Number |
Date |
Country |
1408207 |
Oct 1975 |
GBX |
Continuations (1)
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Number |
Date |
Country |
Parent |
337211 |
Jan 1982 |
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