US3124456A - figure - Google Patents

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US3124456A
US3124456A US3124456DA US3124456A US 3124456 A US3124456 A US 3124456A US 3124456D A US3124456D A US 3124456DA US 3124456 A US3124456 A US 3124456A
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layer
coating
image
recording element
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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
    • G03G5/14—Inert intermediate or cover layers for charge-receiving layers
    • G03G5/147—Cover layers
    • G03G5/14708—Cover layers comprising organic material
    • G03G5/14713—Macromolecular material
    • G03G5/14717—Macromolecular material obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • G03G5/1473—Polyvinylalcohol, polyallylalcohol; Derivatives thereof, e.g. polyvinylesters, polyvinylethers, polyvinylamines
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/22—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20
    • G03G15/226—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 where the image is formed on a dielectric layer covering the photoconductive layer
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/22—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20
    • G03G15/26—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which the charge pattern is obtained by projection of the entire image, i.e. whole-frame projection
    • 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
    • G03G5/10—Bases for charge-receiving or other 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
    • G03G5/14—Inert intermediate or cover layers for charge-receiving layers
    • G03G5/147—Cover layers
    • G03G5/14708—Cover layers comprising organic material
    • G03G5/14713—Macromolecular material
    • G03G5/14717—Macromolecular material obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • G03G5/14721—Polyolefins; Polystyrenes; Waxes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
    • Y10S430/001—Electric or magnetic imagery, e.g., xerography, electrography, magnetography, etc. Process, composition, or product
    • Y10S430/102—Electrically charging radiation-conductive surface

Definitions

  • An electrostatic printing process is that type of process for producing a visible recording, reproduction or copy which includes as an intermediate step, converting a light image or electrical signal into an electrostatic charge pattern.
  • the process usually includes the conversion of the charge pattern into a visible image which may be a substantially faithful reproduction of an original, except that it may be of a different size, or contrast value.
  • a typical electrostatic printing process may include producing an overall electrostatic charge on the surface of a photoconductive material such as selenium, anthracene or zinc oxide dispersed in an insulating binder.
  • a light image is projected on the charged surface, discharging the portions irradiated by the light rays while leaving the remainder of the surface in a charged condition to thus form an electrostatic image.
  • the electrostatic image is rendered visible by applying a developer powder which is held electrostatically to the charged areas of the surface.
  • the powder' image thus formed may be fixed directly to the photoconductive material or may be transferred to another surface upon which a reproduced image may be desired and then xed thereon.
  • the xing step commonly comprises fusing the developer powder to the photoconductor material by the application thereto of heat.
  • Another object of this invention is to provide an electrophotographic recording element of improved sensitivity.
  • a further object is to provide improved methods and means of electrostatic printing which do not require special precautions to prevent exposure of the recording element to ambient light.
  • Another object is to provide improved methods and means of printing utilizing a photosensitive element having a faster speed of response than those previously used in f conventional electrostatic printing processes.
  • Still another object is to provide an improved electrophotographic element having specific electrical properties which impart to said element an improved sensitivity and speed of response.
  • an improved recording element for electrostatic printing comprising a support member having on one surface thereof a layer of photoconductive material which is overcoated with a layer of insulating material.
  • the layer of insulating material has a dielectric constant/ thickness ratio at least equal to and preferably substantially larger than that of the photoconductive layer.
  • the insulating layer is selected to have a Volume resistivity at least equal to that of photoconductive layer. Either the -support member or the insulating layer is substantially transparent to permit exposure of the photoconductive layer to incident radiation.
  • the functioning of the recording element of this invention is dependent on the dielectric constant/ thickness ratios and resistivities of the insulating and photoconducting layers, it is important that these layers be in intimate contact. Should any air or gas gap exist between any portions of the two layers the effective dielectric constant/ thickness ratios thereof would be upset and functioning of the recording element substantially impaired. Thus, in a practical sense, it is essential that the two layers must be formed as an integral unit. This can easily be accomplished by coating, spraying or evaporating insulating material onto the photoconductive layer to form the insulating layer.
  • the method contemplates exposing the Photoconductive layer to a light image while simultaneously or subsequently applying an electric field across the photoconducting layer and the insulating layer.
  • the eld is applied for a time about equal to the time constant of the RC network represented by an incremental area of the insulating layer in series with a corresponding incremental area of the photoconductive layer.
  • FIGURE 1 is a sectional view of a recording element for electrostatic printing constructed in accordance with the invention
  • FIGURE 2 is a sectional View of a modification of the recording element of FIGURE 1;
  • FIGURE 3 is an electrical equivalent circuit represent ⁇ ing the recording element of FIGURE 1;
  • FIGURE 4 is another electrical equivalent circuit representing the recording element of FIGURE 1;
  • FIGURES 5 and 6 are graphs relating to the functioning of recording elements such as those of FIGURES l and 2;
  • FIGURE 7 is a sectional view of a camera that may be used with the recording element of FIGURE 1 to carry out the methods of the invention.
  • FIGURE 8 is a pictorial representation of a method for developing an electrostatic image formed on the recording element of FIGURE 2.
  • a recording element 18 comprises a relatively conductive support member 20 such as a metal plate, paper sheet, aluminized paper, etc. coated on one side with a photoconductive material 22, which in turn is overcoated with a thin transparent insulating dielectric material 24.
  • the support member 20 has a volume restistivity less than that of the photoconductive material.
  • the photoconducting layer 22A is placed contiguousrwith the support member 20.
  • the photoconducting layer 22 comprises a coating of substantially uniform thickness, of .0002 to .004 inch, upon the support member 20.
  • the photoconducting layer 22 comprises, for example, photoconducting powdered cadmium sulfide, powdered cadmium selenide, or sintered cadmium selenide.
  • a detailed description of a method of making a photoconducting layer of sintered cadmium selenide, for example, is disclosed by Thompsen in U.S. Patent 2,765,385.
  • Photoconductive layers including zinc oxide are described in the Young and Greig publication,
  • the insulating layer comprises, for example, Vinylite VYHH, applied by spraying.
  • Vinylite JYHl-I is a polyvinyl chloride-acetate resin manufactured by the Bakelite Corporation, i ew York, NY., and its approximate composition is 87 percent polyvinyl chloride and 13 percent polyvinyl acetate.
  • Other suitable insulators include polystyrene, Lucite, polyvinyl chloride and polyvinyl acetate.
  • another recording element 11d comprises a transparent electrically conductive backing Z such as an electrically conducting glass plate coated on one side with photoconductive material 22, which in turn is overcoated with a thin insulating dielectric material 24.
  • the backing 20 may be a glass plate to which an electrically conductive coating 20'@ such as NESA coating, marketed by the Pittsburgh Plate Glass Co., Pittsburgh, Pennsylvania, is applied. This coating Zila may be produced by treating a glass sheet with tin chloride.
  • Other transparent electrically conducting coatings for example, thin iridescent metallic coatings may also be used.
  • improved electrophotographic recording elements include the following:
  • Example I (FIGURE I) A sheet of paper has a coating thereon comprising a photoconducting layer of Zinc oxide in a binder. This layer has a thickness of about 10-3 cm., a dielectric constant of about 5 and a volume resistivity of about 10l2 ohm-cm. in darkness. This layer is overcoated with one of the following materials to form an insulating layer having the approximate measured electrical properties indicated:
  • Chloride Polyvinyl 2.7 to 6.1-.-- 5.5 104 to 1.2)(10-3 cm 1012 ohm-cm.
  • a metal plate 20 has a photoconductive coating 22 thereon comprising sintered cadmium selenide. This coating has a thickness of about 10-3 cm., a dielectric constant of about 3 and a dark resistivity of about 109 ohm-cm. (resistivity may be varied from 1012 ohm-cm. to as low as 10 ohm-cm. by varying quantities of incorporated impurities such as, for example, chlorine and cop- Example III (FIGURE 2)
  • a glass plate 20 has evaporated thereon a thin conductive layer 20%! of metal or tin chloride.
  • This layer Zil'a is overcoatcd with powdered cadmium suliide which is bonded to the conductive layer Zila with a binder such as, for example, ethyl cellulose.
  • the cadmium sulfide layer 22 has substantially the same electrical properties as the sintered layer 22 of Example H. Hence, the cadmium sulde layer may be provided with an insulating overcoat in the manner set forth in Example II.
  • FIGURE 3 illustrates in schematic form an electrical circuit which characterizes the recording element of FIGURE 1.
  • This equivalent circuit shows the two elements: the insulator to provide for charge storage and the photoconductor for transforming changes in light intensity into changes in electrical resistance thereby controlling the quantity of charge applied to the insulator.
  • the electrically conductive layer or support member 20 is shown pictorially, since it is a good conduct-or and represents only a common connection.
  • Any elemental segment of the photoconducting layer 22 which is coated upon the support member 20 may be represented by a parallel combination of a variable resistor 41% and a capacitor 46.
  • the resistor 44 represents the electrical resistance of an elemental segment of the photoconducting layer, and its value depends upon the intensity of incident light upon the photoconducting layer 22.
  • the capacitor 46 represents the capacitance of this same elemental segment of the photoconductive layer, and its value depends upon the photoconductor material and its dimensions.
  • the insulating layer 24 Coated over the photoconducting layer 22 is the insulating layer 24 whose equivalent circuit for each elemental segment may also be represented by a parallel combination of a iixed resistor 4S and a capacitor 50.
  • the resistor 48 represents the resistance of an elemental segment of the insulating layer
  • the capacitor Sii represents the capacitance of this same elemental segment.
  • This network is connected in series with the network representing the photoconductive layer, since both layers are physically superposed on one another in the recording element.
  • the equivalent circuit of FIGURE 3 is a lumped constant approximation of a system which actually has distributed constants.
  • the networks shown in dotted configuration indicate that a plurality of such networks are required to approximate the recording element over its entire area,
  • the equivalent circuit of FIGURE 4 is obtained.
  • the desirability of this type of circuit will be explained hereinafter.
  • the elemental capacitor 46 of the photoconductive layer and the element resistor 48 of the insulating layer have been neglected in FIGURE 4.
  • the capacitor 46 can be neglected if it is made small compared to the capacitor 50, and the resistor 48 can be neglected if it is made large compared to the resistor 44. Since the resistor 48 represents the resistance of an insulator, which is inherently very large, it can be neglected when compared to the elemental resistance of the photoconductive layer.
  • the value of the capacitor 46 can be neglected if it is made substantially smaller than the value of the capacitor 50. This can be achieved by suitable selection of the photoconductor and insulating layers. For example, assume the photoconductor selected is cadmium sulfide and it is desired to minimize its equivalent elemental capacitance 46.
  • the photoconductive layer should be made as thick as feasible since capacitance is inversely proportional to the thickness. The maximum useable thickness of the photoconductive layer is fixed by the depth of light penetration into the layer. For cadmium sulfide this limit is about microns. If, as in Example II, the cadmitun sulde coating has a dielectric constant of about 3, then the elemental capacitor 46 will have a capacitance of approximately 265 enfarads/cm?.
  • the value of the elemental insulator capacitor 50 is also inversely proportional to the thickness of the insulating layer, it is desirable to make this layer as thin as possible.
  • an insulator having a thickness such as, for example, 2 microns and a dielectric constant of about 5 an insulator elemental capacitance of 2200 ,u.,u.farads/cm.2 is obtained.
  • the insulator capacitor Sil is about 8 times larger than the photoconductor capacitor 46.
  • a lens 56 projects a radiant image such as a light image upon the recording element.
  • the switch is closed for a time less than that necessary to fully charge the insulator capacitor 50. This results in the photoconductor selectively modulating the amount of charge stored in the insulator capacitor in accordance with the amount of light incident upon each elemental photoconductor area.
  • the switch 54 is opened, the charge on the insulator capacitor 50 remains permanently stored since there is now no discharge path. Thus a latent electrostatic image is formed on the insulator layer.
  • the graphs of FIGURES 5 and 6 further illustrate the build-up of charge across the insulator 24 of FIG. 1.
  • An initial measurement is taken at a time, t1, on initiation of charging.
  • the voltage VL across light exposed areas of the insulator 24 is substantially equal to the voltage VD across unexposed areas.
  • Vsigmx a maximum difference between VL and VD is obtained at a time tom. If charging of the recording element is continued, VL will reach a. maximum which will then be rapidly attained by VD.
  • the graph of FIG. 5 illustrates charge build-up on the recording element of FIGURE l wherein the capacitance C, of the insulating layer 24 equals the capacitance Cp of the photoconductive layer 22.
  • layers are chosen so that the resistance Rd of unexposed areas of the photoconductive layer 22 is ten times the resistance of RL of exposed areas.
  • the graphs illustrate qualitatively that there is an optimum charging time (rapt) during which the maximum voltage difference across the insulator layer between exposed and unexposed areas is developed.
  • This optimum charging time is directly dependent upon the time constant of an RC network representing the equivalent circuit through an incremental area of the recording element. This time constant equals RL(Cl-Cp).
  • toptIRLCi 111 R13/RL The latter expression is a suciently accurate means for determining charging time in accordance with this invention.
  • FIGURE 7 A camera and additional accessories for utilizing the novel recording element 18 of FIGURE 2 is shown in FIGURE 7.
  • the camera comprises a lens 26, a bellows 2% and an enclosure 30 for the recording element 18.
  • the recording element is placed in the enclosure 30 and held firmly in position by a pair of insulating spring members 34.
  • the recording element 18 as described heretofore comprises the transparent electrically conducting layer 2li', the photoconducting layer 22 upon said transparent layer 20', and the thin dielectric insulating layer 24 upon the photoconductor layer 22.
  • corona discharge electrode 36 Located in the enclosure 30 and directly behind the insulating layer 24 is a corona discharge electrode 36.
  • This electrode may comprise a plurality of 3 mil corona discharge wires 38 spaced about 0.5 inch from each other and from the insulating layer 34.
  • the wires 3S are housed in a metal shield 4@ in order to direct the corona discharge upon the insulating layer 24.
  • the corona discharge wires 3S are connected to one terminal of a voltage source illustrated as a battery 42. Another terminal of the battery is connected through a switch 43 to the enclosure 3i?. By making the enclosure Si? of electrically conductive material, the layer 20 is connected through the switch 43 to the positive terminal of the battery 42.
  • a voltage of the order of 6090 volts when applied to the wires 38 produces a corona discharge therefrom.
  • the recording element i8 is placed in the camera so that the transparent layer 29 is closest to the lens 26 and a light image therefrom will be incident upon the photoconductor layer 22.
  • a similar exposure procedure to that described heretofore is utilized with the camera of FIGURE 7 to obtain a latent electrostatic image on the recording element.
  • the image 42 is tiret focused on the recording element 18.
  • the switch 43 is then closed for a specied time during or after exposure.
  • the switch i3 is opened, an electrostatic image is recorded on the insulating layer by the mechanism heretofore discussed.
  • the recording element does not undergo an irreversible change upon exposure to light.
  • a latent electrostatic image will be produced on the insulator layer only when a light image isl focused on the recording element and the corona discharge is applied thereto.
  • special precautions against exposure to light are unnecessary during manufacture and distribution and between charging and development of the recording elements.
  • the exposed recording element could be allowed to remain in ambient light for several weeks before development.
  • Another important feature of this invention is that the recording element is exposed strictly on a transient basis, meaning that there is no direct current through the recording element. Consequently the dark current properties of the photoconductor layer are not critical since such properties affect exposure time only.
  • photoconductive materials which have light sensitivities several orders ⁇ of magnitude better than other commonly used electrophotographitc materials may be used.
  • a cadmium sulde photolayer has a sensitivity approximately 800 times that of an electrophotographic material such 7 as photoconductive zinc oxide dispersed in an insulating binder.
  • the electrostatic irnage may be stored for a time if ⁇ desi-red.
  • the next step is to develop the electrostatic image with a finely-divided developer substance such as a finely-divided powder or an ink mist.
  • development of the electrostatic image is preferably accomplished by passing a developer brush 56 containing la developer powder across the surface of the insulating layer 24 bearing the latent electrostatic image.
  • Developer powder 58 is deposited on those areas of the surface reta-ining an electrostatic charge.
  • the developer brush comprises a mixture of magnetic carrier particles, for example, powdered iron and the developer powder.
  • a preferred carrier material for the developer mix consists of alcoholized iron, that is, iron particles free from grease and other impurities soluble in alcohol. These iron particles are preferably relatively small in size, being in their largest dimension about .O02 to .008. Satisfactory results are also obtained using a carrier consisting of iron particles of a somewhat Wider range of sizes up to about .OOil to .020".
  • a preferred developer powder may be prepared as follows.
  • a mixture comprising 200 grams of 200 mesh Piccolastic resin 4358 (an elastic thermoplastic resin composed of polymers of styrene, substituted styrene and its homologs), marketed by the Pennsylvania Industrial Company, Clairton, Pa., 12 grams of Carbon Black G, marketed by the Eimer Iand Amend Co., New York, NY., 12 grams of spirit Nigrosine C.S.B., marketed by the Allied Chemical and Dye Co., New York, N.Y., and 8 grams of Iosol Black, marketed by the Allied Chemical and Dye Co., New York, N.Y., are thoroughly mixed in a stainless steel beaker at about 200 C.
  • the mixing and heating should be done in as short ⁇ a time as possible.
  • the melt is poured into a brass tray and allowed to cool and harden.
  • the hardened mix is then broken up and ball milled for about 20 hours.
  • the powder is screened through a 200 mesh screen and is then ready for use as a developer powder.
  • This powder takes on a positive electrostatic charge when mixed with glass beads or iron powder. It therefore develops an electrostatic image composed of negative charges.
  • a magnetic carrier to developer powder ratio of about 100 to 1 is preferred, although this ratio may vary as widely as between 250 to 1 and 25 to 1 depending on the particular components selected.
  • the developer powder may be chosen from a large class of materials.
  • the developer powder is preferably electrically charged to aid in the development of the electrostatic latent image.
  • the powder may be electrically charged because the powder (1) is electroscopic, or (2) has interacted with other particles with which it is triboelectrica'lly active, or (3) has been charged from an electric source such as a corona discharge.
  • suitable developer powders are powdered zinc, powdered copper, carbon, sulphur, natural and synthetic resins or mixtures thereof.
  • the developer powder may be applied to the image in other ways, for example, it may be dusted onto the image, or it may be mixed with glass beads or other suitable carrier particles and then brought into contact with the surface of the printing base.
  • the beads may serve as a temporary carrier, releasing the powder particles upon contact with the charged surface.
  • Still another method of applying developer powder to the image is by use of a magnetic brush as described in the publication, Electrofax-Direct Electrophotographic Printing on Paper, op. cit.
  • a developer brush is formed by dipping a bar magnet into a mass of developer mix comprising iron particles mixed with a ycarbon pigmented rosin powder in the proportion of about to 1 by weight.
  • the bar magnet may be in any convenient form, .either electromagnetic or permanent.
  • the developer brush is lightly rubbed across the image surface, causing particles of the pigmented resin to transfer from the brush to the charge image, thereby producing a direct powder image.
  • composition of a developer mix for use with the magnetic brush is not critical. While a preferred mixture comprises about 2 percent by weight developer powder, the remainder being iron, satisfactory results may be obtained using a mixture comprising 1 percent to 6 percent by weight developer powder.
  • the developed image 58 is now fixed to the insulating layer 24%.
  • the image may be xed by heating, for example, with an infra red lamp to fuse the powder to the surface.
  • the powder image is preferably fused through the insulating layer 2d. Sulphur or synthetic resin powders may be fixed in this way.
  • the powder image 58 may be pressed into the layer 24.
  • Another method of fixing the powder image 58 is to -apply a thin coating of a solvent for the material of the powder image 58.
  • the solvent may soften the developer powder particles and cause them to adhere to one another and to the layer 2.4i.
  • a solvent may be used to soften the insulator layer 2li and cause the developer powder particles to adhere thereto. Upon standing and preferably with the application of a slight amount of heat the solvent is evaporated from the printing base.
  • a method of electrostatic printing comprising the steps of exposing a photoconductive insulating layer to an electromagnetic radiation image, said layer having an insulating coating on and integral with one surface thereof, the volume under the exposed areas of said layer combining in series with the volume of said coating under the same said areas to provide at least one electrical network having a predetermined time constant, equal to RL(Ci-

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Inorganic Chemistry (AREA)
  • Electrophotography Using Other Than Carlson'S Method (AREA)
  • Photoreceptors In Electrophotography (AREA)
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BE (1) BE584063A (en, 2012)
CH (1) CH375385A (en, 2012)
DE (1) DE1127378B (en, 2012)
FR (1) FR1243971A (en, 2012)
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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3256089A (en) * 1961-08-11 1966-06-14 Xerox Corp Masked plate xerography
US3477846A (en) * 1967-05-01 1969-11-11 Gaf Corp Xerographic charge transfer process
US3652270A (en) * 1969-01-10 1972-03-28 Matsushita Electric Ind Co Ltd Recording devices
US3973956A (en) * 1973-09-14 1976-08-10 Coulter Information Systems, Inc. Electrophotographic process employing signal comparison
US4465754A (en) * 1981-10-27 1984-08-14 Kuin Nicolaas P J Water-fixable electrostatic toner powder containing hydrolyzed polyvinyl ester
US4621919A (en) * 1983-07-13 1986-11-11 Canon Kabushiki Kaisha Metal drum and image holding member using the same
US4862414A (en) * 1986-06-11 1989-08-29 Kuehnle Manfred R Optoelectronic recording tape or strip comprising photoconductive layer on thin, monocrystalline, flexible sapphire base
US4917983A (en) * 1985-10-01 1990-04-17 Konishiroku Photo Industry Co., Ltd. Toner for developing an electrostatic latent image comprising linear polyester polymer
US6162570A (en) * 1996-03-29 2000-12-19 Oce Printing Systems Gmbh Electrophotographic printing process for printing a carrier

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1927190C3 (de) * 1968-05-30 1982-02-04 Canon K.K., Tokyo Elektrophotographieverfahren für Mehrfarbenbedruckung von Textilien

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US2845348A (en) * 1952-01-04 1958-07-29 Kallman Hartmut Electro-photographic means and method
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US2886434A (en) * 1955-06-06 1959-05-12 Horizons Inc Protected photoconductive element and method of making same
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Also Published As

Publication number Publication date
BE584063A (en, 2012)
DE1127378B (de) 1962-04-12
CH375385A (de) 1964-02-29
NL244827A (en, 2012)
FR1243971A (fr) 1960-10-21
GB930403A (en) 1963-07-03

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