US3713734A - Apparatus for forming a positive electrostatic image - Google Patents

Apparatus for forming a positive electrostatic image Download PDF

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Publication number
US3713734A
US3713734A US00197877A US3713734DA US3713734A US 3713734 A US3713734 A US 3713734A US 00197877 A US00197877 A US 00197877A US 3713734D A US3713734D A US 3713734DA US 3713734 A US3713734 A US 3713734A
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United States
Prior art keywords
screen
layer
apertures
image
fields
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Expired - Lifetime
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US00197877A
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English (en)
Inventor
Hewitt D Crane
George J Eilers
Gerald L Pressman
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Markem Imaje Corp
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Electroprint Inc
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Assigned to MARKEM CORPORATION reassignment MARKEM CORPORATION MERGER (SEE DOCUMENT FOR DETAILS). , EFFECTIVE: DEC. 30, 1986. Assignors: ELECTROPRINT, INC.,
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    • 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
    • G03G15/34—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 powder image is formed directly on the recording material, e.g. by using a liquid toner
    • G03G15/344—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 powder image is formed directly on the recording material, e.g. by using a liquid toner by selectively transferring the powder to the recording medium, e.g. by using a LED array
    • G03G15/346—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 powder image is formed directly on the recording material, e.g. by using a liquid toner by selectively transferring the powder to the recording medium, e.g. by using a LED array by modulating the powder through holes or a slit

Definitions

  • ABSTRACT A machine for making a copy on a medium such as paper of a visual image.
  • Particles of toner material are [52] U.S.Cl. ..355/3,355/4;)2/6l/l2, accelerated toward the p p through an apertured [51] Int. Cl. ..G03g 15/00 scren'hpormed 9 Screen is a g f deem) [58] Field of Search ..355/3,4, 16, 17; 96/1, 1.2 c We COmSP S f ""j that the arrangement of the toner part1cles 1mp1ng1ng 56 References Cited on the paper corresponds to the image.
  • a composite apertured screen composed of two conductwe layers UNITED STATES PATENTS separated by an insulative layer and having an insula- 3,339,469 9/1967 McFarlane ..355/l6 five layer on Outer eeanstor establishing 3,532,422 10/1970 McFarlane ..96/1.2 PP y Polanzed fields across the Inner msulatlve 3,582,206 6/1971 Burdige ..355/16 layer and across the outer insulative layer.
  • Such systems can include a support for a medium such as paper on which it is desired to form a visible image.
  • the system also can include a source of particles that have a color contrasting with that of the medium. (Such particles are typically referred to as toner, and such usage will be employed hereinafter).
  • toner typically referred to as toner, and such usage will be employed hereinafter.
  • a plurality of electrostatic charge regions is formed by the screen in a pattern that corresponds to the image so that electrostatic fields within the apertures selectively control passage of toner particles.
  • Toner particles egressing from the apertured screen therefore conform to the pattern of the image. After the toner particles impinge on the medium they can be fixed or fused thereon, if required, in accordance with known technology to provide a permanent image.
  • ions or like charged particles are formed into a suitable pattern which pattern can be directed through a cloud of toner particles.
  • the screen according to the present invention is useful in both types of system or in any other system in which formation of a pattern of charged particles is required.
  • the present invention provides an improved screen that offer certain advantages over various prior screens.
  • the screen construction according to the present invention operates at a relatively low voltage thereby simplifying fabrication and operation of the device.
  • the embodiment of the invention described in more detail hereinafter includes a composite apertured screen formed by four layers.
  • the composite screen On the upstream or obverse face of the screen, the side facing the source of toner particles, the composite screen has a conductive layer underlying which is an insulative layer.
  • a second conductive layer On the downstream face of the insulative layer is a second conductive layer underlying which is an outer insulative layer; the exposed surface of the outer insulative layer constitutes the downstream or reverse face of the screen.
  • the improved screen is incorporated into the system by so biasing the two conductive layers that within the apertures is established an electrostatic blocking field that has a polarity and magnitude sufficient to block the passage of toner particles through the apertures.
  • the outer insulative layer is selectively electrostatically charged to a polarity and magnitude sufficient to form a field that counteracts and overrides portions of the blocking field to afi'ord passage of toner particles in a pattern corresponding to an image.
  • the outer insulative layer is formed of photoconductive material, a material that has a high resistance when in a dark state and a low resistance when in an illuminated state. While in the dark state, the photoconductive layer is charged to a polarity and magnitude sufficient to create fields within the apertures that override or counteract the abovementioned blocking field. Consequently, when the screen is in a dark state, all apertures are biased to permit passage of toner particles traveling from the toner particle source to the medium. The image to be copied on the medium is then projected on the photoconductive layer so that portions of that layer that correspond to light parts of the image assume a conductive state.
  • FIG. I is a diagrammatic view of a system employing the screen of the present invention.
  • FIG. 2 is an enlarged fragmentary view of a screen according to the present invention showing the position of the electrostatic fields within an aperture;
  • FIG. 3 is a fragmentary view of a larger portion of a screen constructed according to the present invention.
  • FIG. 4 is a fragmentary view similar to FIG. 3 showing the charged condition of the screen prior to receiving an image thereon;
  • FIG. 5 is a view similar to FIGS. 3 and 4 showing the charged condition of the screen after a visible image has been impressed on the photoconductive layer thereon;
  • FIG. 6 is a diagrammatic view similar to FIG. I showing an alternate embodiment of the invention.
  • FIG. 7 is a diagrammatic view of another alternate embodiment of the invention.
  • reference numeral 12 schematically indicates an air and light impervious enclosure in which a system employing the improved screen of the invention is enclosed.
  • a source of toner particles 14 mounted within enclosure 12 is a source of toner particles 14, a composite apertured screen 16, an image receiving medium 18 and a conductive support 20 for the medium.
  • a power source 22 is provided for establishing a field between toner source 14 and conductive plate 20 so that toner particles are accelerated from .the toner source to the conductive plate.
  • Screen 16 defines a large plurality of apertures 24 in which apertures appropriate fields are established either to block or to pass toner particles in accordance with the shape of an image I to be formed on medium 18.
  • a charged particle source such as a corona source 26, which is employed to form a uniform charge on the reverse surface 28 of screen 24.
  • an image source 30 is projected onto the reverse surface of screen 24 through an optical system that includes a reflector 32 and a shutter mechanism 34. Illumination of reverse face 28 of screen 24 alters the charge pattern within the apertures of screen 24 so that toner particles egress from the screen apertures in a pattern corresponding to image source 30, whereby the image I is formed on medium 18.
  • a satisfactory embodiment of screen 16 is fragmentarily shown at greatly enlarged size in FIG. 2.
  • the screen includes an obverse face 36 that faces toward the source of toner particles.
  • Obverse face 36 is defined by a conductive layer 38 underlying which is an insulative layer 40.
  • On the surface of insulative layer 40 opposite from conductive layer 36 is a second or inner conductive layer 42; screen 16 is structurally completed by a layer 44 of photoconductive material the outer surface of which defines reverse surface 28 of screen 16.
  • insulative layer 40 and photoconductive layer 44 have thicknesses of approximately 0.001- inch and conductive layers 38 and 42 are thin films deposited on such insulative layers.
  • apertures 24 have a diameter of approximate ly 0.006-inch and as shown in the figure, the apertures extend through all layers so that each layer terminates in the wall bounding the apertures.
  • Blocking fields are formed within apertures 24 by establishing a bias or potential between conductive layers 38 and 42 that has a magnitude and polarity sufficient to form a charge across insulative 40 that creates the blocking field.
  • a bias or potential between conductive layers 38 and 42 that has a magnitude and polarity sufficient to form a charge across insulative 40 that creates the blocking field.
  • toner particle source 14 is biased to charge toner particles with a negative charge
  • conductive layer 38 is biased positively with respect to conductive layer 42.
  • Such bias is achieved by connecting a tap 46 in power source 22 to conductive layer 38 and by connecting a tap 48 of the power source to conductive layer 42.
  • the effect of such bias is to form at the surface of insulative layer 40 that abuts conductive layer 38 a plurality of positive charges and at the surface of the insulator that abuts conductive layer 42 a plurality of negative charges; the fringe of such charges within each aperture 24 form an electrostatic field within the aperture identified by field lines 50 which have a magnitude and polarization sufficient to block passage of toner particles through the aperture.
  • a potential between conductive layers 38 and 42 of about 200-300 volts is considered adequate to form a field within aperture 24 that totally blocks passage of toner particles through the aperture.
  • the'present invention provides for creation of an electrostatic field that counteracts or overrides the field designated by field lines 50.
  • the field lines of the counteracting field are identified by reference numeral 52.
  • Such counteracting field is formed by impressing on surface 28 of photoconductive layer 44, while such layer is in the dark or nonconductive state, charges of a suitable polarity, positive charges in the case exemplified in the drawings.
  • Such charges can be formed by any suitable expedient, for example, by bombardment of surface 28 with positive ions from a corona wand, radioactive source, or the like.
  • the charges impressed on reverse surface 28 are of a magnitude and polarity such that the counteracting field indicated by field lines 52 is formed by the cooperation of the charges on surface 28 and the charges existing on the surfaces of inner insulative layer 40.
  • the charges formed on reverse face 28 are more positive than the charges arising from the bias supplies connected to conductive layers 38 and 42.
  • the field formed between the charges on reverse face 28 and the charges on the surfaces of inner insulator 40 cause fringe fields within aperture 24 that have a magnitude and direction sufficient to counteract blocking field 50 to the end that the toner particles can pass through aperture 24, a condition that subsists so long as conductive layer 44 is retained in a dark state.
  • Projection of image I onto reverse surface 28 illuminates all portions of the conductive layer except those areas corresponding to the location of dark lines and/ or areas of the image. Those portions of photoconductive layer 44 that are illuminated become locally conductive so that current flow through the layer is permitted. Such current flow discharges counteracting field 52 in all apertures 24 that are associated with light portions of image I so that only blocking field 50 exists in such apertures. In apertures corresponding to dark areas of the image, however, no current flow occurs through photoconductive layer 44 as a consequence of which counteracting fields 52 subsist in such apertures.
  • a typical image projected on. the reverse face of screen 16 includes regions that have no contrasting information, regions that are completely black (or other contrasting color), and regions that are intermediate the two extremes (e.g., varying degrees of gray).
  • the present invention permits accurate reproduction of all regions of the image.
  • regions of the layer become conductive in proportion to the intensity of light impinging thereon.
  • Regions of the photoconductive layer corresponding to bright or highlight portions of the image are maximally illuminated and therefore substantially totally discharged.
  • Regions of the photoconductive layer corresponding to gray portions of the image are only partially illuminated and therefore only partially discharged.
  • Regions of the photoconductive layer, corresponding to black portions of the image are not illuminated and therefore not discharged. Accordingly, passage of toner particles through various apertures 24 in screen 16 occurs in direct proportion to the position and relative intensity in the image.
  • FIG. 3 depicts screen 16 as it exists after power source 22 has been activated.
  • a potential difference between inner electrode 42 and outer electrode 38 establishes blocking fields 50 within each aperture 24 so that any negatively charged toner particles approaching the obverse face, the lower face as viewed in FIGS. 3, 4 and 5, will be blocked and, therefore, will not pass through the apertures in the screen.
  • FIG. 4 depicts the screen after a charge from particle source 26 has been impressed on photoconductive layer 44 while the screen is in a dark condition. In such state, counteracting fields 52 are established within apertures 24 which fields fully or partially override blocking fields 50 so that the net effect within each aperture so affected is that toner particles approaching the screen will pass through the screen.
  • the region to the left labeled illuminated area and indicated by reference numeral 54 corresponds with portions of. an image that are clear, or bright, whereas the remainder of the screen corresponds with portions of the image that are black or of some other contrasting color.
  • photoconductive layer 44 becomes locally conductive and the charges thereon that sustain counteracting field 52 are dissipated. Consequently, as to the apertures within the illuminated area, e.g., aperture 24a, blocking field 50 is solely effective so that toner particles e.g., 14a, are repelled by the field and do not pass through aperture 24a.
  • the counteracting field remains effective to override the blocking field so that the toner particles e.g., 14b, can pass through such apertures.
  • Those apertures in regions of the screen that are partially illuminated will pass toner particles in reduced quantities. Accordingly, an image is formed downstream, i.e., above, as viewed in FIG. 5, of the plate 16 by toner particles identified by reference number 140.
  • FIGS. 6 and 7. a modified screen 16 is shown.
  • conductive layers 38 and 42 and inner insulative layer 40 are identical to the structure described above and therefore bear identical reference numerals; in the modified screen, however, photoconductive layer 44 is replaced by an insulative or dielectric layer that is insensitive to light. Because layer 60 is formed of insulative material, it can store a charge in the dark or in the light in the same manner that photoconductive layer 44 stores a charge when in a dark condition.
  • counteracting fields 52 have been established by impression of a charge on conductive layer 60 in a manner equivalent to that described hereinabove; i.e., by bombardment from a corona source or the like.
  • Plate 61 includes a transparent support layer 62 on one surface in which is placed a thin, transparent conductive layer 64. Overlying transparent conductive layer 64 is a photoconductive layer 66'adapted for contact with insulative layer 60 of screen 16. A suitable bias potential is applied to the plate by connection to conductive layer 64. In a dark condition, plate 61 is moved into contact with insulative layer 60 after which the visible image is projected through transparent layers 62 and 64 onto photoconductive layer 66. The regions of the photoconductive layer that are illuminated become conductive and therefore discharge fields 52 on corresponding regions of plate 16'. Consequently, the charge distribution on insulative layer 60 is selectively modified in accordance with the image projected onto plate 61 so that upon removal ofthe plate and acceleration of toner particles through screen 16', the toner particles will be arranged in accordance with the visible image.
  • FIG. 7 shows still another modification wherein screen 16 is identical to that described above in connection with FIG. 6.
  • the embodiment of FIG. 7 includes a plate 68 on which has been formed a latent electrostatic image in accordance with the procedures disclosed in U.S. Pat. applications Ser. No. 673,499 and Ser. No. 776,I46.
  • the charges on plate 68 that define an electrostatic latent image thereon are transferred to the surface of insulative layer 60 of screen 16' when the plate is brought into physical contact with the screen.
  • Such charges form counteracting fields 52 in only those apertures through which it is desired to admit toner particles.
  • the intermediate step of impressing counteracting field 52 throughout the entire area of the screen is eliminated.
  • the present invention provides an improved screen for forming an electrostatic image which is positive in reference to a visual image, to the end that positive images on a suitable medium can be formed by a screen according to this invention.
  • the screen is capable of operation at relatively low voltages and is of relatively uncomplex construction.
  • Apparatus for forming an electrostatic image that corresponds to an optical image comprising a composite screen defining a plurality of spaced apart apertures and having an outer conductive layer forming the obverse face of said screen, an insulative layer superposed on said outer conductive layer, an inner conductive layer superposed on said insulative layer, and a photoconductive layer superposed on said inner conductive layer and forming the reverse face of said screen, means connected between said outer conductive layer and said inner conductive layer for establishing a voltage gradient across said insulative layer, said voltage gradient forming a first electrostatic field that extends into said apertures to form blocking fields within said apertures polarized in a first direction, means for establishing a charge on said reverse face that forms in cooperation with said inner and outer conductive layers a second field in said apertures that has a polarity and magnitude sufficient to counteract said first field when said photoconductive layer is in a dark condition, and means for impressing the optical image on said reverse face so that relatively light regions of said image cause corresponding regions of
  • Apparatus for forming a positive image of an object on a surface comprising a plurality of particles, means for forming an electric field between said particles and a particle receiving surface for accelerating the particles on a path toward said surface, a particle pervious screen disposed in said path in substantial parallelism with said surface, said screen having a reverse face facing said surface, an obverse face opposite said reverse face, and a plurality of apertures extending therethrough between said obverse face and said reverse face, said apertures being of sufficient size to admit said particles therethrough, said screen including an electrically conductive outer layer on said obverse face, an electrically insulative layer underlying said outer conductive layer, an electrically conductive inner layer underlying said insulative layer and a photoconductive layer underlying said inner conductive layer and defining said reverse face, means for establishing a first electric field between said inner and outer conductive layer so polarized as to repel particles approaching the apertures from the direction of said obverse face, means for establishing a second electric field between said
  • a system for controlling the flow of a stream of charged particles comprising:
  • Apparatus for forming a positive image of an object on a surface with a plurality of particles comprising means for forming an electric field between the particles and a particle receiving surface for accelerating the particles on a path toward said surface, a particle pervious screen disposed in said path in substantial parallelism with said surface, said screen having a reverse face facing said surface, an obverse face opposite said reverse face, and a' plurality of apertures extending therethrough between said obverse face and said reverse face, said apertures being of sufficient size to admit said particles therethrough, said screen including an electrically conductive outer layer on said obverse face, an electrically insulative layer underlying said outer conductive layer, an electrically conductive inner layer underlying said insulative layer and a photoconductive layer underlying said inner conductive layer and defining said reverse face, means for establishing a first electric field between said inner and outer conductive layer so polarized as to repel particles approaching the apertures from the direction of said obverse face, means for establishing a second electric field between

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Photoreceptors In Electrophotography (AREA)
  • Electrophotography Using Other Than Carlson'S Method (AREA)
US00197877A 1971-11-11 1971-11-11 Apparatus for forming a positive electrostatic image Expired - Lifetime US3713734A (en)

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JP (1) JPS5642868B2 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
CA (1) CA1021006A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
CH (1) CH579293A5 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
DE (1) DE2255132A1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
FR (1) FR2159885A5 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
GB (1) GB1419520A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
IT (1) IT966842B (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
NL (1) NL7214968A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5036136A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) * 1973-08-01 1975-04-05
US3942980A (en) * 1974-07-16 1976-03-09 Addressograph-Multigraph Corporation Ion modulator device and method of using in positive and negative modes
US4014694A (en) * 1972-08-17 1977-03-29 Electroprint, Inc. Method and apparatus for forming a positive electrostatic image
US4086088A (en) * 1976-03-25 1978-04-25 Addressograph Multigraph Corporation Imaging methods for use with charged particle modulator device
DE2809790A1 (de) * 1977-03-07 1978-09-14 Olympus Optical Co Verfahren und vorrichtung zum elektrofotografischen herstellen von mehreren kopien von einer vorlage bei nur einer belichtung
JPS5412752A (en) * 1978-05-16 1979-01-30 Canon Inc Photosensitvie screen
US4141650A (en) * 1976-06-24 1979-02-27 Olympus Optical Company Limited Improved shutter apparatus for electrophotographic apparatus
US4158564A (en) * 1977-04-04 1979-06-19 Electroprint, Inc. Method and apparatus for controlling the gray scale response of a multilayer image forming screen
US4168164A (en) * 1976-07-08 1979-09-18 Konishiroku Photo Industry Co., Ltd. Screen process for forming electrostatic latent images
US4218124A (en) * 1977-11-22 1980-08-19 Konishiroku Photo Industry Co., Ltd. Photo-sensitive screen for producing electrostatic latent image
US4272597A (en) * 1977-06-24 1981-06-09 Masaji Nishikawa Electrophotographic sensitizing screen
US4332876A (en) * 1973-06-19 1982-06-01 Canon Kabushiki Kaisha Electrophotographic screen
US4600292A (en) * 1983-04-07 1986-07-15 Konishiroku Photo Industry Co., Ltd. Photoconductive screen

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4006983A (en) * 1973-10-29 1977-02-08 Electroprint, Inc. Electrostatic color printing systems using modulated ion streams
JPS53108441A (en) 1977-03-04 1978-09-21 Olympus Optical Co Ltd Zerographic apparatus

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CA553355A (en) * 1958-02-18 International Business Machines Corporation Apparatus and method for xerographic printing
DE1156308B (de) * 1956-01-10 1963-10-24 Albert Lieb Verfahren und Vorrichtung zur Herstellung von Bildern auf elektrophotographischem Wege
JPS41832Y1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) * 1964-06-16 1966-01-27
US3339469A (en) * 1962-08-06 1967-09-05 Sun Chemical Corp Electrostatic printing apparatus
US3532422A (en) * 1966-07-14 1970-10-06 Electroprint Inc Method and apparatus for electrostatic color reproduction
US3582206A (en) * 1968-03-01 1971-06-01 Electroprint Inc Ion projection aperture-controlled electrostatic printing system
US3603790A (en) * 1968-04-30 1971-09-07 Kodak Ltd Electroradiographic process

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US3680954A (en) * 1965-04-30 1972-08-01 Eastman Kodak Co Electrography

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CA553355A (en) * 1958-02-18 International Business Machines Corporation Apparatus and method for xerographic printing
DE1156308B (de) * 1956-01-10 1963-10-24 Albert Lieb Verfahren und Vorrichtung zur Herstellung von Bildern auf elektrophotographischem Wege
US3339469A (en) * 1962-08-06 1967-09-05 Sun Chemical Corp Electrostatic printing apparatus
JPS41832Y1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) * 1964-06-16 1966-01-27
US3532422A (en) * 1966-07-14 1970-10-06 Electroprint Inc Method and apparatus for electrostatic color reproduction
US3582206A (en) * 1968-03-01 1971-06-01 Electroprint Inc Ion projection aperture-controlled electrostatic printing system
US3603790A (en) * 1968-04-30 1971-09-07 Kodak Ltd Electroradiographic process

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4014694A (en) * 1972-08-17 1977-03-29 Electroprint, Inc. Method and apparatus for forming a positive electrostatic image
US4675261A (en) * 1973-06-19 1987-06-23 Canon Kabushiki Kaisha Electrophotographic process with a photoconductive screen
US4340296A (en) * 1973-06-19 1982-07-20 Canon Kabushiki Kaisha Electrophotographic apparatus
US4332876A (en) * 1973-06-19 1982-06-01 Canon Kabushiki Kaisha Electrophotographic screen
JPS5036136A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) * 1973-08-01 1975-04-05
US3942980A (en) * 1974-07-16 1976-03-09 Addressograph-Multigraph Corporation Ion modulator device and method of using in positive and negative modes
US4086088A (en) * 1976-03-25 1978-04-25 Addressograph Multigraph Corporation Imaging methods for use with charged particle modulator device
US4141650A (en) * 1976-06-24 1979-02-27 Olympus Optical Company Limited Improved shutter apparatus for electrophotographic apparatus
US4168164A (en) * 1976-07-08 1979-09-18 Konishiroku Photo Industry Co., Ltd. Screen process for forming electrostatic latent images
DE2809790A1 (de) * 1977-03-07 1978-09-14 Olympus Optical Co Verfahren und vorrichtung zum elektrofotografischen herstellen von mehreren kopien von einer vorlage bei nur einer belichtung
US4158564A (en) * 1977-04-04 1979-06-19 Electroprint, Inc. Method and apparatus for controlling the gray scale response of a multilayer image forming screen
US4272597A (en) * 1977-06-24 1981-06-09 Masaji Nishikawa Electrophotographic sensitizing screen
US4279980A (en) * 1977-06-24 1981-07-21 Olympus Optical Co., Ltd. Electrophotographic sensitizing screen
US4394427A (en) * 1977-06-24 1983-07-19 Olympus Optical Company Limited Electrophotographic sensitizing screen with peripherally clogged apertures
US4218124A (en) * 1977-11-22 1980-08-19 Konishiroku Photo Industry Co., Ltd. Photo-sensitive screen for producing electrostatic latent image
JPS5412752A (en) * 1978-05-16 1979-01-30 Canon Inc Photosensitvie screen
US4600292A (en) * 1983-04-07 1986-07-15 Konishiroku Photo Industry Co., Ltd. Photoconductive screen

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FR2159885A5 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1973-06-22
GB1419520A (en) 1975-12-31
JPS5642868B2 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1981-10-07
IT966842B (it) 1974-02-20
CH579293A5 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1976-08-31
CA1021006A (en) 1977-11-15
AU4695272A (en) 1974-03-28
JPS4859840A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1973-08-22
NL7214968A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1973-05-15
DE2255132A1 (de) 1973-05-17

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Free format text: MERGER;ASSIGNOR:ELECTROPRINT, INC.,;REEL/FRAME:004765/0682

Effective date: 19861231