Classifications

• • 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
  • G03G5/08—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being inorganic
  • G03G5/082—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being inorganic and not being incorporated in a bonding material, e.g. vacuum deposited
• • 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

Definitions

• recording plates with a conducting substrate on which there is deposited a photoconductive layer of semiconducting material on which a charge pattern is produced by the charge and exposure to light, corresponding to the image pattern.
• This charge pattern is made visible by the application of a suitable inking powder which, in the course of a further step of the process, is transferred from the recording plate to a sheet of paper where it is fixed.
• recording plates employing selenium as the semiconducting material.
• Certain additives to the selenium improve the electrophotographic properties.
• the metal substrate on which the selenium layer is deposited consists either of a rigid metal plate or of a metal cylinder, or else of a flexible metal foil, such as a steel tape. Onto this metal substrate the selenium is usually deposited by way of evaporation under vacuum.
• the known electrophotographic recording plates with a selenium layer still have certain disadvantages. First, it is impossible for larger black areas to be reproduced as such, because the charge on the selenium layer is chiefly positioned in the marginal areas of the thus imaged surfaces.
• a method of preparing a selenium charge electrophotographic recording plate having a selenium layer deposited on a metal substrate comprising the steps of depositing selenium on a metal substrate by evaporation under vacuum to form a selenium layer, depositing a thin coating of a semiconducting material on a metal plate, subjecting the selenium coated metal substrate and said metal plate having a semiconducting material thereon to a glow discharge whereby a portion of said semiconducting material is deposited on said selenium layer.
• the application of the semiconducting substance is effected in such a way that a metal plate provided with a coating of the semiconducting substance to be used, is arranged as the cathode in a glow discharge, while the anode is formed by the selenium layer of the recording plate. Both the cathode and the anode are arranged at a certain distance apart each other in a suitable gas atmosphere.
• gases for the glow discharge it has proved particularly suitable to use inert gases, such as nitrogen or rare gases.
• a further improvement in the reproducibility of the selenium layers can be obtained in that the metal plate used as the cathode, is provided on its surface facing the selenium surface, with a pattern of recesses. These recesses may also extend entirely through the metal plate forming the cathode, so that the cathode is a perforated metal plate.
• the glow discharge is preferably carried out under a pressure in the order of 10 to 10 torr (mm Hg). In the course of this, there is used a voltage in the order of 800 to 2,000 V, with the current flow amounting to values between 20 and 200 milliamperes.
• the selenium surface is exposed to this glow discharge for a period of time ranging between half a minute and sixty minutes.
• an inert gas is used for the glow discharge, hence a gas which, under the glow-discharge conditions does not chemically combine with either the substrate material or the selenium.
• a suitable inert gas it is possible to use e.g. nitrogen or else a rare gas, such as argon.
• oxygen may be used as the gas for the glow discharge.
• Oxygen of course, reacts with the selenium, but this reaction has no influence upon the desired effect. No disadvantageous effects upon the electrophotographic properties of the selenium have been noticed when using oxygen.
• Suitable semiconducting materials for depositing onto the selenium surface are, in particular, semiconducting cadmium compounds, semiconducting zinc compounds and semiconducting titanium oxide.
• cadmium sulfide and cadmium selenide are particularly suitable.
• zinc oxide and zinc sulfide are particularly suitable.
• the selenium is deposited by way of evaporation under vacuum in the form of a layer in the order of 10 to microns thick.
• the selenium may still be provided with small additions.
• the selenium-coated substrate is placed at a suitable distance from a metal plate provided with a thin coating of the semiconducting material to be deposited, in an inert gas atmosphere under a pressure of l to torr, and a voltage is applied ranging between 800 and 2000 V.
• the metal plate provided with the layer of semiconducting substance to be deposited forms the cathode while the selenium layer forms the anode.
• glow discharge there will flow a current ranging between and 200 milliamperes. Action lasts for a period ranging between half a minute and sixty minutes.
• the resulting electrophotographic recording plates show substantially improved reproducibility, especially of larger black areas, and permit reproduction of a large number of gray scales.
• the surface of a selenium layer is subjected as the cathode to the glow discharge.
• a polished plate of aluminum is preferably used as the anode.
• Glow discharge is carried out under the above described conditions causing a great number of slight imperfections in the selenium surface during glow discharge. The imperfections are uniformly distributed over the entire selenium surface, however, the disintegration of the image into individual spots does not occur as is the case when using an optical raster.
• a method of preparing a selenium charge electrophotographic recording plate having a selenium layer deposited on a metal substrate comprising the steps of:
• selenium on a metal substrate by evaporation under vacuum to form a selenium layer; depositing a thin coating of a semiconducting material selected from the group consisting of cadmium sulfide, zinc oxide and zinc sulfide on a metal plate; thereafter sputtering a portion of said semiconducting material on said selenium layer by subjecting the selenium coated metal substrate and said metal plate to a glow discharge.
• a semiconducting material selected from the group consisting of cadmium sulfide, zinc oxide and zinc sulfide

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Photoreceptors In Electrophotography (AREA)

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Citations (4)

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• 1974
  • 1974-02-05 US US439807A patent/US3901783A/en not_active Expired - Lifetime
  • 1974-02-07 JP JP49014980A patent/JPS5116779B2/ja not_active Expired
  • 1974-02-08 ES ES423026A patent/ES423026A1/es not_active Expired

Patent Citations (4)

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