Claims
- 1. In an electrophotographic article in which substrate means carry thin film coatings at least one of which is a thin film coating of a photoconductive material less than 1 micron in thickness, means contiguous to the coating to facilitate uniform charging thereof before exposure; the invention comprising, said coating being very dense, wholly inorganic, microcrystalline, the crystals of said coating being generally uniformly oriented vertically relative to the surface of the substrate means, substantially free of effective barrier layers between the crystals, the coating having light transmissivity of at least 70 percent, having a dark resistivity of at least 10.sup.12 ohm-centimeters and a ratio between dark and light resistivity of at least about 10.sup.4 and being electrically anisotropic whereby said coating is capable of accepting a rapid charge and retaining same sufficient to enable toning.
- 2. The article as claimed in claim 1 in which said substrate means are transparent.
- 3. The article as claimed in claim 1 in which the means to facilitate uniform charging of the coating comprise a thin film layer of ohmic material sandwiched between the coating and substrate means.
- 4. The article as claimed in claim 1 in which said substrate means, the coating and the means to facilitate charging are flexible.
- 5. The article as claimed in claim 1 in which said substrate means comprise a transparent member; in which said thin film coating material is a semiconductor and is characterized by no greater than 85 percent light transmission; and in which the means to facilitate charging comprise a thin layer of ohmic material between said substrate means and said coating.
- 6. The article as claimed in claim 1 in which said substrate means comprise a flexible, transparent, organic polymer sheeting member; in which the light transmissivity of the coating is no greater than 85 percent, in which said coating is a semiconductor and flexible; and in which the means to facilitate charging comprise a thin layer of ohmic material between said substrate means and said thin film coating, said thin layer also being flexible.
- 7. An article as claimed in claim 1 in which said thin film coating material is dominantly cadmium sulfide.
- 8. An article as claimed in claim 2 in which said thin film coating material is dominantly cadmium sulfide.
- 9. An article as claimed in claim 3 in which said thin film coating material is dominantly cadmium sulfide.
- 10. An article as claimed in claim 4 in which said thin film coating material is dominantly cadmium sulfide.
- 11. An article as claimed in claim 5 in which said thin film coating material is dominantly cadmium sulfide.
- 12. An article as claimed in claim 5 in which the semiconductor is n-type.
- 13. An article as claimed in claim 6 in which the semiconductor is n-type.
- 14. An article as claimed in claim 3 in which said thin-film coating and said thin film layer are together less than around 5000 Angstroms thick.
- 15. An article as claimed in claim 5 in which said thin film coating and said thin film layer are together less than around 5000 Angstroms thick.
- 16. An article as claimed in claim 6 in which said thin film coating and said thin film layer are together less than around 5000 Angstroms thick.
- 17. An article as claimed in claim 1 in which said thin film coating is at least primarily zinc indium sulfide.
- 18. An article as claimed in claim 2 in which said thin film coating is at least primarily zinc indium sulfide.
- 19. An article as claimed in claim 3 in which said thin film coating is at least primarily zinc indium sulfide.
- 20. An article as claimed in claim 4 in which said thin film coating is dominantly zinc indium sulfide.
- 21. An article as claimed in claim 5 in which said thin film coating is dominantly zinc indium sulfide.
- 22. An article as claimed in claim 6 in which said thin film coating is dominantly zinc indium sulfide.
- 23. An article as claimed in claim 1 in which the said thin film coating is doped with a dopant.
- 24. An article as claimed in claim 2 in which the said thin film coating is doped with a dopant.
- 25. An article as claimed in claim 3 in which the said thin film coating is doped with a dopant.
- 26. An article as claimed in claim 1 in which said thin film coating is doped with copper.
- 27. An article as claimed in claim 2 in which said film coating is doped with copper.
- 28. An article as claimed in claim 3 in which said thin film coating is doped with copper.
- 29. An article as claimed in claim 1 in which the said thin film coating is doped with iodine.
- 30. An article as claimed in claim 2 in which the said thin film coating is doped with iodine.
- 31. An article as claimed in claim 3 in which the said thin film coating is doped with iodine.
- 32. An article as claimed in claim 3 in which said thin film coating is about 3000 Angstroms thick and said film layer is less than 1000 Angstroms thick.
- 33. An article as claimed in claim 5 in which said thin film coating is about 3000 Angstroms thick and said thin film layer less than 1000 Angstroms thick.
- 34. An article as claimed in claim 6 in which said thin film coating is about 3000 Angstroms thick and said film layer is less than 1000 Angstroms thick.
- 35. An article as claimed in claim 3 in which said thin film layer is at least primarily indium oxide.
- 36. An article as claimed in claim 4 in which said means to facilitate charging are at least primarily indium oxide.
- 37. An article as claimed in claim 5 in which said thin film layer is at least primarily indium oxide.
- 38. An article as claimed in claim 6 in which said thin film layer is at least primarily indium oxide.
- 39. An article as claimed in claim 7 in which said thin film layer is at least primarily indium oxide.
- 40. An article as claimed in claim 8 in which said thin film layer is at least primarily indium oxide.
- 41. An article as claimed in claim 35 in which the thin film layer also includes a small amount of tin oxide.
- 42. An article as claimed in claim 36 in which the thin film layer also includes a small amount of tin oxide.
- 43. An article as claimed in claim 37 in which the thin film layer also includes a small amount of tin oxide.
- 44. An article as claimed in claim 38 in which the thin film layer also includes a small amount of tin oxide.
- 45. An article as claimed in claim 39 in which the thin film layer also includes a small amount of tin oxide.
- 46. An article as claimed in claim 40 in which the thin film layer also includes a small amount of tin oxide.
- 47. The article as claimed in claim 6 in which means are provided for increasing the bonding of said thin film layer and thin film coating to the substrate means.
- 48. The article as claimed in claim 47 in which said bond increasing means comprises a second thin film layer of a transparent wholly inorganic material between the first thin film layer and the substrate means.
- 49. The article as claimed in claim 48 in which the second thin film layer is a photoconductor and has a thickness that is a small fraction of the first thin film layer.
- 50. The article as claimed in claim 49 in which the thin film layers are cadmium sulfide.
- 51. In an electrophotographic member which includes a substantially transparent thin film coating of a sputtered semiconductor on a flexible substrate of insulative material with a thin film, flexible transparent ohmic layer sandwiched between the coating and substrate; the improvement comprising; said coating being wholly inorganic, microcrystalline, flexible, substantially transparent, having the crystals thereof oriented uniformly generally vertically relative to the surface of the substrate to which the coating is applied, substantially free of effective barrier layers between the crystals, the coating having a dark resistivity of at least 10.sup.12 ohm-centimeters and a ratio of dark to light resistivities of at least 10.sup.4 and being electrically anisotropic whereby to be capable of accepting a charge and retaining same to such a degree as to enable toning.
- 52. The article as claimed in claim 51 in which there is a thin film bonding layer of substantially the same material as the thin film coating interposed between the ohmic layer and the substrate but having a thickness substantially less than either the coating or the ohmic layer.
- 53. The article as claimed in claim 51 in which means are provided to establish electrical contact from said ohmic layer to circuitry exterior of the article.
- 54. The article as claimed in claim 51 in which the ohmic layer is a semiconductor.
- 55. For use with electrophotographic members or the like, a thin film photoconductive coating r.f. sputter deposited upon a suitable substrate, said coating being wholly inorganic, microcrystalline in highly ordered uniform arrangement, oriented generally vertically relative to the surface of the substrate, substantialy free of effective barrier layers between the crystals, being an n-type semiconductor, being chemically stable and abrasion resistant, having high photoelectric gain, having uniform morphology and stoichiometry, being electrically anisotropic whereby it is capable of accepting and retaining a charge to a degree enabling toning, the dark resistivity of said coating being at least 10.sup. 12 ohm-centimeters and the ratio of dark to light resistivities being at least 10.sup.4.
- 56. The photoconductive coating as claimed in claim 55 in which said coating has a transmissivity between 70 and 85 percent.
- 57. The photoconductive coating as claimed in claim 55 in which the photoconductive coating is substantially transparent.
- 58. The photoconductive coating as claimed in claim 55 in which the coating is flexible.
- 59. The photoconductive coating as claimed in claim 55 in which the coating is cadmium sulfide about 3000 to 5000 Angstroms thick.
- 60. The photoconductive coating as claimed in claim 55 in which the dark resistivity is substantially increased upon charging in darkness.
- 61. The photoconductive coating as claimed in claim 56 in which the dark resistivity is substantially increased upon charging in darkness.
- 62. The photoconductive coating as claimed in claim 58 in which the dark resistivity is substantially increased upon charging in darkness.
- 63. The photoconductive coating as claimed in claim 59 in which the dark resistivity is substantially increased upon charging in darkness.
- 64. The photoconductive coating as claimed in claim 59 in which the coating is doped with a dopant.
- 65. In an electrophotographic film structure which includes a substrate having a thin film ohmic layer bonded to a surface thereof and a wholly inorganic thin film photoconductive coating bonded to the ohmic layer and sandwiching the layer between the substrate and the coating, the improvement comprising a film structure having the following properties:
- A. physical--the coating is microcrystalline, oriented uniformly generally vertical to the surface to which bonded, is substantially free of effective barrier layers between the crystals, is substantially inert to humidity, temperature variations and most radiation; has indefinite shelf life; is highly abrasion resistant; is very dense;
- B. optical--the film structure has between 70 percent and about 85 percent light transmissivity; and when charged and exposed to a radiation pattern, has a broad generally unpeaked spectral response; and
- C. electrical--the coating is an n-type semiconductor; is electrically anisotropic; can accept and sustain a rapid charge at a tonable level to achieve toned resolution as great as 1000 lines/mm; has a surface resistivity of at least 10.sup.12 ohm-centimeters; has a relatively low light resistivity permitting total light discharge with practically no residual charge; and has no persistent photoconductivity.
- 66. An electrophotographic film structure as claimed in claim 65 which has the following additional properties:
- A. physical--the substrate, layer and coating are flexible and capable of being rolled to a diameter of less than 1/2 inch without damage, the total thickness of the coating and layer is about 5000 A; and
- B. electrical--the coating has a speed of discharge during exposure comparable with that of high speed conventional photographic film.
- 67. The structure as claimed in claim 66 in which the coating is cadmium sulfide.
- 68. The structure as claimed in claim 65 in which there is a thin film bonding layer between the ohmic layer and the substrate member of substantially the same material as said coating and having a thickness substantially less than that of said ohmic layer.
- 69. The structure as claimed in claim 66 in which there is a thin film bonding layer between the ohmic layer and the substrate member of substantially the same material as said coating and having a thickness substantially less than that of said ohmic layer.
- 70. The structure as claimed in claim 67 in which there is a thin film bonding layer between the ohmic layer and the substrate member of substantially the same material as said coating and having a thickness substantially less than that of said ohmic layer.
- 71. The structure as claimed in claim 67 in which the layer is indium oxide.
- 72. The structure as claimed in claim 67 in which the layer is a combination of indium oxide with a lesser amount of tin oxide.
- 73. In an electrophotographic member of the type having a photoconductive coating which is initially uniformly charged and thereafter exposed to a pattern of nonuniform radiation providing photons for selective discharge of the uniform charge to provide a latent image of remaining charge corresponding to the pattern of the nonuniform radiation the improvement comprising:
- A. a substrate of insulating material
- B. a photoconductive coating carried as a deposit upon the substrate and characterized by the following properties:
- 1. made of wholly inorganic material,
- 2. r.f. cathodic sputtered
- 3. generally uniformly vertically oriented crystalline,
- 4. of a sufficient thickness to enable absorption of relatively few photons to be sufficient to provide total discharge of the exposed surface,
- 4. n-type,
- 6. providing a substantial number of recombination centers,
- 7. having a dark resistivity greater than 10.sup.12 ohm-centimeters considered statically and substantially greater than 10.sup.12 ohm-centimeters considered dynamically,
- 8. a ratio of dark to light resistivity of at least 10.sup.4,
- 9. chemically stable and abrasion resistant,
- 10. electrically anisotropic,
- 11. being capable of accepting and retaining a charge to a degree to enable it to be exposed and toned and
- 12. is substantially free of effective barrier layers between the crystals and
- C. means including a generally electrically conductive plane in association with the substrate to enable charging of the photoconductive coating by corona or the like, the combining centers being independent of the electrical plane such that said means to enable charging of said coating are neither used nor required during discharge thereof.
- 74. The electrophotographic member as claimed in claim 73 in which the electrical plane is located between the substrate and the coating.
- 75. The electrophotographic member as claimed in claim 73 in which the electrical plane comprises a layer of ohmic material sandwiched between the substrate and the coating, the layer and coating and substrate all being intimately bonded together.
- 76. The electrophotographic member as claimed in claim 75 in which the ohmic material is conductive in at least one transverse direction.
- 77. A method for manufacturing an electrophotographic film article which comprises:
- depositing a thin film layer of ohmic material upon a flexible thin organic transparent substrate in thoroughly bonded condition and a thickness which renders said thin film layer substantially transparent and flexible and
- r.f. direct cathodic sputtering a thin, electrically anisotropic film coating less than one micron in thickness of a wholly inorganic photoconductor material upon said ohmic material in a generally uniformly vertically oriented microcrystalline, substantially free of effective barrier layers between the crystals, thoroughly bonded condition and a thickness which provides a gain of said photoconductor material which is hight and which is substantially transparent and flexible,
- the total thickness of said article having a light transmissivity of not less than 70 percent and not more than about 85 percent, in which the sputtering is carried out in a chamber having an anode and a cathodic target formed of the material to be sputtered under conditions producing the usual dark space at the target, connecting the cathodic target to the high side of an r.f. generator and maintaining the anode on the negative side of ground whereby to produce a second dark space during sputtering.
- 78. The method as claimed in claim 77 in which the photoconductor material is doped during deposit by introducing a dopant into said r.f. field.
- 79. The method as claimed in claim 77 in which there is an extremely thin bonding layer of the same material as said coating is r.f. sputtered onto the substrate before the ohmic layer is deposited.
- 80. The method as claimed in claim 77 in which the ohmic layer is deposited by sputtering.
- 81. The method as claimed in claim 77 in which the ohmic layer is deposited by sputtering.
- 82. The method as claimed in claim 80 in which the sputtering is carried out in a chamber having an anode and a cathodic target formed of the material to be sputtered under conditions producing the usual dark space at the target, connecting the cathodic target to the high side of an r.f. generator and maintaining the anode on the negative side of ground whereby to produce a second dark space during sputtering.
- 83. In a method of manufacturing an article wich includes a substrate and a photoconductive coating bonded to the substrate, the step of depositing a thin film photoconductive coating on the substrate comprising the steps of establishing in a sputtering chamber a plasma between a cathodic target of photoconductive material to be sputtered and an anode carrying a substrate, connecting the cathodic target to the high negative side of the output of an r.f. generator and maintaining the anode below ground whereby to establish a Langmuir dark space between the plasma and the anode in addition to the ordinary dark space, and continuing the sputtering until a thin, electrically anisotropic film coating including said photoconductive material is coated upon a surface of said substrate in a uniformly ordered, microscrystalline layer with the crystals oriented uniformly generally vertically relative to said substrate surface, substantially free of effective barrier layers between the crystals.
- 84. The method as claimed in claim 83 in which the anode is heated.
- 85. The method as claimed in claim 83 in which the photoconductive material is cadmium sulfide.
- 86. The method as claimed in claim 85 in which hydrogen sulfide gas is introduced into the chamber as a background gas during the sputtering.
- 87. A method for manufacturing an electrophotographic article that is capable of being charged and toned and which comprises:
- A. placing a substrate member having at least a surface that is conductive in an r.f. sputtering chamber in position to have the surface sputtered, the said surface being arranged to form substantially the anode in said chamber,
- B. positioning a target of a chemical compound formed of at least two inorganic elements and no organic elements in the chamber, the compound when sputtered producing a coating which is photoconductive in nature,
- C. connecting the target and anode in an r.f. sputtering circuit in which the target is effectively the cathode at a high negative voltage with respect to ground and the anode is negatively control-biased with respect to ground,
- D. sputtering in a non-reactive mode a coating of said compound onto the substrate to form a wholly inorganic photoconductive material on the substrate which is generally uniformly vertically oriented microcrystalline, substantially free of effective barrier layers between the crystals, electrically anisotropic, having a surface resistivity which is of the order of 10.sup.12 ohm-centimeters in lateral directions when charged in darkness or discharged in light and also transversely of the coating in darkness, and which has a light resistivity transversely of the coating which is of the order of 10.sup.8 ohm-centimeters or less, which is chemically stable and abrasion resistant and which is capable of accepting a charge and retaining it to a degree enabling the coating to be toned,
- E. the sputtering being carried on in an atmosphere that includes dominantly an inert but ionizable gas for forming a plasma between the target and substrate with a dark space at the target and the bias being such as to provide a second dark space at the substrate, with an additional background gas being introduced into the chamber along with the inert gas to prevent decomposition of the compound at the target or during deposition, and
- F. continuing the sputtering process until the thickness of the coating is at least sufficient to provide maximum photoconductive gain.
- 88. The method as claimed in claim 87 in which the compound is cadmium sulfide, the background gas is hydrogen sulfide and the bias voltage of the anode is substantially less than minus 200 volts.
CROSS-REFERENCE TO RELATED APPLICATIONS
This is a continuation of Ser. No. 434,699, filed Jan. 18, 1974, now abandoned.
This application is a continuation-in-part of three copending applications as follows:
Application Ser. No. 378,180 filed July 11, 1973 entitled "ELECTROPHOTOGRAPHIC FILM, METHOD OF MAKING AND USING THE SAME AND PHOTOCONDUCTIVE COATING USED THEREWITH", now abandoned, which in turn is a continuation-in-part of the second copending application, Ser. No. 323,132 filed Jan. 12, 1973 entitled, "ELECTROPHOTOGRAPHIC FILM AND METHOD OF MAKING AND USING THE SAME", now abandoned, said copending application in turn being a continuation-in-part of the third copending application Ser. No. 260,848 filed June 8, 1972 and entitled, "ELECTRO-PHOTOGRAPHIC FILM", now abandoned.
Reference may be had to copending applications, Ser. No. 389,149 filed Aug. 17, 1973 entitled, "IMAGE RECORDING METHOD FOR ELECTROPHOTOGRAPHIC FILM" and Ser. No. 397,309 filed Sept. 14, 1973 entitled, now U.S. Pat. No. 3,864,035, "SHUTTERLESS CAMERA SYSTEM" for disclosures concerned with the method of use of the electrophotographic film of the invention.
All applications are owned by the same assignee.
US Referenced Citations (11)
Non-Patent Literature Citations (2)
Entry |
Kay et al., "Photoconductivity in Sputtered Zinc Oxide Films", IBM Tech. Discl. Bull., vol. 12, No. 6, Nov. 1969, p. 851. |
Lagnads et al., Rf-Sputtered Cadmium Sulfide Thin Crystals", Journ. Val. Sci. Tert., vol. 7, No. 2, Mar.-Apr. 1970, pp. 318-321. |
Continuations (1)
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434699 |
Jan 1974 |
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Continuation in Parts (2)
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323132 |
Jan 1973 |
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260848 |
Jun 1972 |
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