US3915076A - Photoconductive plate which is sensitive when charged either positively or negatively - Google Patents

Photoconductive plate which is sensitive when charged either positively or negatively Download PDF

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US3915076A
US3915076A US430083A US43008374A US3915076A US 3915076 A US3915076 A US 3915076A US 430083 A US430083 A US 430083A US 43008374 A US43008374 A US 43008374A US 3915076 A US3915076 A US 3915076A
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layer
organic insulating
inorganic photoconductive
type
photoconductive layer
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US430083A
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Katsuhiko Gotoda
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Kyocera Mita Industrial Co Ltd
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Mita Industrial Co Ltd
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/02—Charge-receiving layers
    • G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
    • G03G5/043—Photoconductive layers characterised by having two or more layers or characterised by their composite structure
    • G03G5/0436—Photoconductive layers characterised by having two or more layers or characterised by their composite structure combining organic and inorganic layers
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/02—Charge-receiving layers
    • G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
    • G03G5/043—Photoconductive layers characterised by having two or more layers or characterised by their composite structure
    • G03G5/0433—Photoconductive layers characterised by having two or more layers or characterised by their composite structure all layers being inorganic
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/14—Inert intermediate or cover layers for charge-receiving layers
    • G03G5/142—Inert intermediate layers

Definitions

  • ABSTRACT A novel photosensitive plate which has a sensitivity regardless of the polarity of the applied charge is disclosed.
  • Said photosensitive plate comprises (a) an electroconductive substrate, (b) a first inorganic photoconductive layer formed on said substrate, (0) a substantially transparent, organic insulating layer formed on said first inorganic photoconductive layer and (d) a second inorganic photoconductive layer formed on said organic insulating layer.
  • Said photosensitive plate is characterized in that the first inorganic photoconductive layer is identical with the second photoconductive layer with respect to the type of the photoconductive material used, namely the N-type or P-type, and when the inorganic photoconductive layers are of the N-type, the organic insulating layer is composed of an organic insulating material having a long range for electrons and when the inorganic photoconductive layers are of the Ptype, the organic insulating layer is composed an organic insulating material having a long range for positive holes.
  • FIG. 2-A is a diagrammatic representation of FIG. 2-A
  • This invention relates to a photosensitive plate for use in electrophotography. More particularly, the invent on relates to a photosensitive plate for electrophotography which has a high sensitivity when charged eitherpositively or negatively.
  • conventional photosensitive plates for use in electrophotography which include a photoconductive material, especially an inorganic photoconductive material, show a photosensitivity only when a charge of one specific polarity, positive or negative, is applied on the surface thereof.
  • a photoconductive material especially an inorganic photoconductive material
  • P-type photoconductive materials such as selenium
  • N-type photoconductive materials such as zinc oxide and cadmium sulfide show a photosensitivity only when they are negatively charged.
  • a photosensitive plate for electrophotography is provided with such a property that it can have a sensitivity to a projected light when it is charged either posi tively or negatively, there will be attained an advantage that a desired positive or negative copied image can be obtained from an original of either a positive or negative image merely by changing the polarity of the applied charge without changing the kind of the developer used.
  • a photosensitive plate having such specific property will also be advantageous in that it can freely replace any of photosensitive plates to be used in commercially available electrophotographic copying machines, namely either electrophotographic copying machines sensitizing photosensitive plates by application of a positive charge or electrophotographic copying machines sensitizing photosensitive plates by application of a negative charge.
  • a photosensitive plate for electrophotography comprising a laminate of a layer of an inorganic photoconductive material such as selenium and a layer of an organic insulating material such as poly-N- vinylcarbazole has an excellent transparency and a low dark decay.
  • a photosensitive plate for electrophotography formed by laminating, in order, an electroconductive substrate, an organic insulating layer and a photoconductive layer is disclosed in the specification of US. Pat. No. 3,573,906. This photosensitive plate is transparent and advantageous in that the charge quantity can be increased though the photoconductive layer is thin.
  • This photosensitive plate shows the sensitivity only when the applied charge has a specific polarity, either positive or negative, and this selectivity depends on whether the photoconductive layer is composed of a P-type photoconductive material or N-type photoconductive material. Accordingly, it is very difficult to obtain a photosensitive plate having the foregoing specific property according to this known technique.
  • a photosensitive plate for electrophotography formed by laminating, in order, an electroconductive substrate, a photoconductive layer and an organic semiconductor layer is proposed in Japanese Patent Publication No. 5349/70. Although also this photosensitive plate is excellent in the transparency and flexibility, it shows a sensitivity only when a charge of one specific polarity is applied on the organic semiconductive layer.
  • a photosensitive plate formed by subjecting zinc oxide to a special treatment so that it may be made sensitive under application of charges of both positive and negative polarities has recently been proposed, but none of photosensitive plates of this type have a practical utility.
  • Another object of this invention is to provide a photosensitive plate capable of giving a copy of a desired image which is either positive or negative merely by changing the polarity of the applied charge at the charging step without changing the kind of the developer used.
  • a photosensitive plate for use in electrophotography which has a sensitivity when it is charged either positively or negatively, said photosensitive plate comprising (a) an electroconductive substrate, (b) a first inorganic photoconductive layer formed on said electroconductive substrate, said first inorganic photoconductive layer having preferably a thickness of at least 0.2g, (0) a substantially transparent, organic insulating layer formed on said first inorganic photoconductive layer, said organic insulating layer having preferably a thickness of l to 30,u, and (d) a second inorganic photoconductive layer formed ,on said organic insulating layer, said second inorganic.
  • the photoconductive layer having preferably a thickness "of 0.2 to 1p, wherein the first inorganic photoconductive layer (b) is identical with the second inorganic photoconductive layer (d) with respect to the type of the photoconductive material used, namely the N-type or P-type, and when the photoconductive layers are of the N-type, the organic insulating layer is composed of an organic insulating material having a long range for electrons and when the photoconductive layers are of the P-type, the organic insulating layer is composed of an organic insulating material having a long range for positive holes.
  • FIG. 1 is a view illustrating diagrammatically the section of the photosensitive plate of this invention
  • FIGS. 2-A and 2-B are curves showing the chargelight exposure characteristics of known photosensitive plates.
  • FIG. 3 is a curve showing the charge-light exposure characteristics of the photosensitive plate of this invention.
  • an inorganic photoconductive layer 2 is formed in a thickness of 0.2 to several microns on an electroconductive substrate 1 by vacuum evaporation or coating, and an organic insulating layer 3 of a thickness of several to 30 microns having a transparency is coated on said inorganic photoconductive layer 2. Further, an inorganic photoconductive layer 4 having a thickness of 0.2 to 1 micron is formed on said organic insulating layer 3 by vacuum evaporation.
  • any of conventional substrates can be used as the electroconductive substrate 1.
  • an electroconductive substrate prepared by forming a thin layer of copper on a transparent plastic film by vacuum evaporation deposition and reacting iodine with the resulting copper film an electroconductive substrate formed by vacuum evaporation chromium or an alloy of chromium with nickel thinly on a transparent plastic film, or a transparent film composed of a resin of a relatively high conductivity such as cellophane and polyvinyl alcohol.
  • inorganic photoconductive materials can be used for inorganic photoconductive layers 2 and 4.
  • P-type photoconductive materials such as selenium and selenium-tellurium alloys
  • N-type photoconductive materials such as cadmium sulfide, cadmium selenide, zinc oxide, zinc sulfide and titanium dioxide. It also is possible to employ products obtained by sensitizing these photoconductive materials with impurities or colorants so that electron-hole pairs can be formed effectively under application of actinic lights.
  • an organic insulating layer 3 is formed between the first and second inorganic photoconductive layers 2 and 4.
  • the type of the photoconductive material namely the N-type or P-type, is identical in both the photoconductive layer 2 and 4.
  • the polarity of the majority charge carrier of the first inorganic photoconductive layer 2 is identical with the polarity of the majority charge carrier of the second inorganic photoconductive layer 4. It is most desired that both the inorganic photoconductive layers 2 and 4 are composed of the same inorganic photoconductive material.
  • the thickness is so adjusted that formation of electron-hole pairs under application of actinic lights is not inhibited. In general, it is sufficient that the thickness is such that the light transmission does not exceed 80 percent, though this [imitative value varies to some extent depending on the kind of the photoconductive material. It also is necessary that the thickness of the second inorganic photoconductive layer 4 should not inhibit incidence of light into the first inorganic photoconductive layer and should give a light transmission of at least 50 percent.
  • each layer has a thickness of at least 0.2 1.
  • the sec- 0nd photoconductive layer has a thickness of up to 1 1., especially up to 0.4 1. in the case of selenium.
  • photoconductive differing in the spectral sensitivity are employed as the inorganic photoconductive layers 2 and 4, it is possible to obtain a photosensitive plate showing different sensitivity-wavelength characteristics depending on whether the polarity of the applied charge is positive or negative.
  • selenium-tellurium alloys having a sensitivity to rays having a wavelength of 350 to 750 mg is used as the inorganic photoconductive layer 2 and selenium having a sensitivity to rays having a wavelength of 350 to 500 mu is employed as the inorganic photoconductive layer 4, the resulting photosensitive plate has a sensitivity mainly to rays having a wavelength of 350 to 500 mp. when charged positively, and it shows a sensitivity to all of rays within the visible range when charged negatively.
  • the organic insulating layer 3 is provided to hold the charge on the surface and render the plate sensitive to either a negative or positive charge. If the insulating layer 3 has a transparency, it need not be photoconductive. Namely, any of materials capable of capturing the charge carrier and transporting it can be employed. In this invention, it is important that an organic insulating material which can readily transport a charge carrier of the same polarity as that of majority carrier of inorganic photoconductive materials used as inorganic photoconductive layers 2 and 4 is used as the organic insulating layer 3.
  • organic insulating materials having a long range for positive holes such as N-ethylcarbazole, poly-N- vinylcarbazole, tetraphenylpyrene, polyacenaphthylene, perylene, chrysene, 2,3-benzochrysene and 6,7- benzopyrene
  • organic insulating materials having a long range for electrons such as polyvinylanthrathene, tetracyanopyrene, 2,4,7-trinitro-9-fluorene, dinitroanthrathene and dinitroacridine are preferably employed as the organic insulating layer 3.
  • the photoconductive materials to be used as the inorganic photoconductive layers 2 and 4 and the organic insulating material to be used as the organic insulating layer 3 are in close proximity to one another with respect to the energy level of conduction band of the majority charge carrier, because injection of the charge carrier from the photoconductive layer to the insulating layer or from the insulating layer to the photoconductive layer can easily be accomplished.
  • the inorganic insulating layer meeting the above requirements is disposed between the first and second inorganic photoconductive layers meeting the above requirement.
  • FIG. 2-A In the case of a known photosensitive plate formed by laminating, in order, an insulating layer of poly-N- vinyl-carbazole and a photoconductive layer of selenium on an electroconductive substrate, as is illustrated in FIG. 2-A, an excellent photosensitivity is attained when it is charged positively, but no substantial photosensitivity is attained when it is charged negatively. In contrast, in the case of another known photosensitive plate formed by laminating, in order, a photoconductive layer of selenium and a poly-N-vinyl-carbazo le layer on an electroconductive substrate, as is shown in FIG. 2-B, an excellent photosensitivity can'be attained when it is charged negatively, but the photosensitivity attained when it is chargedpositively is as'low as not actually utilizable for electrophotographic process.
  • a photosensitive plate of this invention having a specific laminate structure comprisingfirst and second photoconductive layers and an organic insulating layer has as illustrated in FIG. 3, an excellent pho'tosensitivity when it is charged either positively or negativelyi
  • this invention is based on the novel concept that in a laminated photosensitive plate having two photosensitive layers, i.e., first and second inorganic photoconductive layers 2 and 4, electron-hole pairs are generated in both the photoconductive layers simultaneously on light exposure and extinguish the surface charge by different processes depending on the polarity of the applied charge.
  • each of 'inorganic photoconductive layers 2 and 4 is composed of a P-type inorganic photoconductive material and the organic insulating layer is composed of an insulating material having a'long range for positive holes
  • the polarity of the charge is positive
  • electron-hole pairs are generated simultaneously on light exposure in both the first and second-inorganic photoconductive layers 2 and4
  • electrons generated in the inorganic photoconductive layer 4 extinguish the surface charge and positive holes generated in the inorganic photoconductive layer 4 pass through the organic insulating layer 3 and inorganic photoconductive layer 2 and are earthed to the electroconductive substrate 1.
  • EXAMPLE 1 Chromium was deposited on polyethylene terephthalate by vacuum evaporation to such an extent that the transmission of white light was about 80 percent. Then, amorphous selenium was deposited in a thickness of 0.2g. on the chromium layer by vacuum evaporation. Then, a solution comprising 40 parts by weight of poly-N-vinylcarbazole, 160 parts by weight of tolune and 40 parts of cyclohexanone was coated on the selenium layer in such an amount that the dry thickness would be 5 to lO,u..
  • the resulting laminate assembly was completely dried at room temperature, and amorphous selenium was deposited in a thickness of 0.2;; on the poly-N-vinylcarbazole layer by vacuum evaporation.
  • the transmission of white light of the plate as a whole was about 45 percent.
  • the so obtained photosensitive plate was positively charged bycorona discharge means and exposed to an original having a light-and-shadow image under radiation of white light at 'a rateof about 20 luxes per second.
  • a toner having a charge of the negative polarity by a known development method such as magnetic brush and cascade de' velopment methods, a positive image as clear as the original image was obtained.
  • EXAMPLE 2 Amorphous selenium was deposited in a thickness of lp. on a sufficiently polished aluminium plate by vacuum evaporation, and a solution composed of 10 parts by weight of polyacenaphthylene and 50 parts by weight of toluene was coated thereon in such an amount that the dry thickness would. be 5 to 10p"
  • the plate was then dried completely at room temperature, and amorphous selenium was deposited thereon in a thickness of 0.2g. by vacuum evaporation.
  • the resulting plate was positively or negatively charged, exposed and developed in the same manner as in Example 1, and the formed image was transferred onto white paper. Thus was obtained a clear image of a high contrast.
  • a photosensitive plate for use in electrophotography which has a sensitivity when it is charged either positively or negatively, said photosensitive plate comprising (a) an electroconductive substrate, (b) a first inorganic photoconductive layer formed on said electroconductive substrate, said first inorganic photoconductive layer having a thickness of at least 0.2 mu, (c) a substantially transparent, organic insulating layer formed on said first inorganic photoconductive layer, said organic insulating layer having a thickness of 1 to 30 mu, and (d) a second photoconductive layer formed on said organic insulating layer, said second inorganic photoconductive layer having a thickness of 0.2 to 1 mu, wherein the first inorganic photoconductive layer (b) is identical with the second inorganic photoconductive layer ((1) with respect to the type of the photoconductive material, namely the N-type or P-type, and when the photoconductive layers are of the N-type, the organic insulating layer is composed of an organic insulating material having a long range for electrons and selected from the group consisting of polyvinylanth
  • a photosensitive plate for use in electrophotography which has a sensitivity when it is charged either positively or negatively, said photosensitive plate comprising (a) an electroconductive substrate, (b) a first inorganic photoconductive layer of a thickness of at least 0.2/J. formed on said electroconductive substrate, said first inorganic photo-conductive layer being composed of amorphous selenium, (c) a substantially transparent, organic insulating layer of a thickness of l to 30/1.
  • said organic insulating layer being composed of poly-N-vinylcarbazole
  • An electrostatic photographic process comprising applying a charge of a prescribed polarity uniformly on the surface of a photosensive layer of an electrophotographic plate, and exposing the charged photosensitive layer to a light image to be recorded to form an electrostatic latent image on the surface of the photosensitive layer
  • said photosensitive plate comprises (a) an electroconductive substrate, (b) a first inorganic photoconductive layer formed on said electroconductive substrate, said first inorganic photoconductive layer having a thickness of at least 0.2 mu, (a) a substantially transparent organic insulating layer formed on said first inorganic photoconductive layer, said organic insulating layer having a thickness of l to 30 mu, and (d) a second inorganic photoconductive layer formed on said organic insulating layer, said second inorganic photoconductive layer having a thickness of 0.2 to l mu, said first inorganic photoconductive layer being identical with the second inorganic photoconductive layer with respect to the type of the photoconductive material, namely the N-type or P-type, and when the photoconductive layers are

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  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Photoreceptors In Electrophotography (AREA)
US430083A 1972-12-30 1974-01-02 Photoconductive plate which is sensitive when charged either positively or negatively Expired - Lifetime US3915076A (en)

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JP (1) JPS4991646A (enrdf_load_stackoverflow)
DE (1) DE2364967C3 (enrdf_load_stackoverflow)
FR (1) FR2212568B1 (enrdf_load_stackoverflow)
GB (1) GB1403290A (enrdf_load_stackoverflow)
IT (1) IT1000405B (enrdf_load_stackoverflow)
NL (1) NL7317474A (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4047945A (en) * 1975-02-18 1977-09-13 Xerox Corporation Xeroprinting master and process
US4281054A (en) * 1979-04-09 1981-07-28 Xerox Corporation Overcoated photoreceptor containing injecting contact
US4292385A (en) * 1979-09-04 1981-09-29 A. B. Dick Company Bi-modal photoreceptor and method
US4420547A (en) * 1980-10-16 1983-12-13 Olympus Optical Company Ltd. Photosensitive member for electrophotography having ultraviolet absorption layer
US4489148A (en) * 1983-04-25 1984-12-18 Xerox Corporation Overcoated photoresponsive device
US4650737A (en) * 1985-01-26 1987-03-17 Hoechst Aktiengesellschaft Electrophotographic recording material containing benzimidazole derivative

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS561059A (en) * 1979-06-18 1981-01-08 Hitachi Ltd Electrophotographic receptor
US4343881A (en) * 1981-07-06 1982-08-10 Savin Corporation Multilayer photoconductive assembly with intermediate heterojunction
US4410616A (en) * 1982-05-10 1983-10-18 Xerox Corporation Multi-layered ambipolar photoresponsive devices for electrophotography

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3041166A (en) * 1958-02-12 1962-06-26 Xerox Corp Xerographic plate and method
US3655377A (en) * 1966-10-03 1972-04-11 Xerox Corp Tri-layered selenium doped photoreceptor
US3679405A (en) * 1967-08-26 1972-07-25 Fuji Photo Film Co Ltd Electrophotographic element having a series of alternate photoconductive and insulating layers
US3704121A (en) * 1968-09-21 1972-11-28 Fuji Photo Film Co Ltd Electrophotographic reproduction process using a dual layered photoreceptor
US3725058A (en) * 1969-12-30 1973-04-03 Matsushita Electric Ind Co Ltd Dual layered photoreceptor employing selenium sensitizer

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS558532B2 (enrdf_load_stackoverflow) * 1971-08-11 1980-03-04
JPS4945737A (en) * 1972-09-02 1974-05-01 Tokyo Shibaura Electric Co Denshishashinyo kankoban

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3041166A (en) * 1958-02-12 1962-06-26 Xerox Corp Xerographic plate and method
US3655377A (en) * 1966-10-03 1972-04-11 Xerox Corp Tri-layered selenium doped photoreceptor
US3679405A (en) * 1967-08-26 1972-07-25 Fuji Photo Film Co Ltd Electrophotographic element having a series of alternate photoconductive and insulating layers
US3704121A (en) * 1968-09-21 1972-11-28 Fuji Photo Film Co Ltd Electrophotographic reproduction process using a dual layered photoreceptor
US3725058A (en) * 1969-12-30 1973-04-03 Matsushita Electric Ind Co Ltd Dual layered photoreceptor employing selenium sensitizer

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4047945A (en) * 1975-02-18 1977-09-13 Xerox Corporation Xeroprinting master and process
US4281054A (en) * 1979-04-09 1981-07-28 Xerox Corporation Overcoated photoreceptor containing injecting contact
US4292385A (en) * 1979-09-04 1981-09-29 A. B. Dick Company Bi-modal photoreceptor and method
US4420547A (en) * 1980-10-16 1983-12-13 Olympus Optical Company Ltd. Photosensitive member for electrophotography having ultraviolet absorption layer
US4489148A (en) * 1983-04-25 1984-12-18 Xerox Corporation Overcoated photoresponsive device
US4650737A (en) * 1985-01-26 1987-03-17 Hoechst Aktiengesellschaft Electrophotographic recording material containing benzimidazole derivative

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FR2212568B1 (enrdf_load_stackoverflow) 1979-10-19
IT1000405B (it) 1976-03-30
FR2212568A1 (enrdf_load_stackoverflow) 1974-07-26
JPS4991646A (enrdf_load_stackoverflow) 1974-09-02
DE2364967A1 (de) 1974-07-11
DE2364967B2 (de) 1977-08-25
NL7317474A (enrdf_load_stackoverflow) 1974-07-02
GB1403290A (en) 1975-08-28
DE2364967C3 (de) 1978-04-27

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