US3820985A - Method and apparatus for inductive electrophotography - Google Patents

Method and apparatus for inductive electrophotography Download PDF

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Publication number
US3820985A
US3820985A US00215873A US21587372A US3820985A US 3820985 A US3820985 A US 3820985A US 00215873 A US00215873 A US 00215873A US 21587372 A US21587372 A US 21587372A US 3820985 A US3820985 A US 3820985A
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United States
Prior art keywords
toner
image
insulative member
invention according
electrostatic
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US00215873A
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English (en)
Inventor
J Gaynor
T Anderson
L Tyler
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Bell and Howell Co
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Bell and Howell Co
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Publication date
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Priority to US00215873A priority Critical patent/US3820985A/en
Priority to GB5605872A priority patent/GB1403218A/en
Priority to CA159,713A priority patent/CA990339A/en
Priority to IT33665/72A priority patent/IT972987B/it
Priority to DE2263903A priority patent/DE2263903A1/de
Priority to JP48004542A priority patent/JPS4879641A/ja
Priority to AU50723/73A priority patent/AU5072373A/en
Priority to FR7300433A priority patent/FR2167790B1/fr
Priority to US05/445,377 priority patent/US3937572A/en
Application granted granted Critical
Publication of US3820985A publication Critical patent/US3820985A/en
Assigned to MORGAN GUARANTY TRUST COMPANY OF NEW YORK reassignment MORGAN GUARANTY TRUST COMPANY OF NEW YORK SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BHW MERGER CORP.
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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
    • G03G15/226—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
    • G03G15/227—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 the length of the inner surface of the dielectric layer being greater than the length of the outer surface of 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
    • G03G15/01—Apparatus for electrographic processes using a charge pattern for producing multicoloured copies
    • G03G15/0142—Structure of complete machines
    • 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
    • G03G15/01—Apparatus for electrographic processes using a charge pattern for producing multicoloured copies
    • G03G15/0142—Structure of complete machines
    • G03G15/0147—Structure of complete machines using a single reusable electrographic recording member
    • G03G15/0152—Structure of complete machines using a single reusable electrographic recording member onto which the monocolour toner images are superposed before common transfer from the recording member
    • G03G15/0163—Structure of complete machines using a single reusable electrographic recording member onto which the monocolour toner images are superposed before common transfer from the recording member primary transfer to the final recording medium
    • 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

Definitions

  • a thin insulative film is applied to be in direct contact with a surface carrying an electrostatic image which has a potential sufficient for adherence by induction of toner to the insulative film but insufficient to discharge when in contact with or upon separation of the toned insulative film.
  • the surface is photoconductive, it is exposed before or after contact with the insulative film to a pattern of discharging radiation to form an electrostatic image thereon.
  • toner is applied to the insulative film while in direct contact with the imaged surface. Thereafter, the toner image may be transferred to a support member. Toning and toner transfer is repeated without further charge and without further exposure.
  • Apparatus utilizing the above image forming technique requires that the photoconductive layer be specially prepared to resist the abrasive effects of'exposure to toner powder and operations associated with the application, transfer of the toner powder and removal of residual unwanted toner. These effects limit the useful life of the photoconductive medium and gradually degrade copy image quality. Furthermore. such machines do not produce multiple copies from a single exposure and particularly cannot produce multiple copies bearing two or more different colors.
  • Dessauer U.S. Pat. No. 3,013,878 discloses the use of a flexible transfer material in the form of a continuous belt of insulating material applied to the surface of a photoconductive drum.
  • the belt is uniformly charged and image-wise discharged so that an electrostatic image is formed on its surface.
  • the belt is toned, separated from the drum and the toner image is transferred to'a support sheet.
  • the belt continues onto the photoconductive drum surface where it is again charged and selectively discharged for the production of further copies. Since the belt carries an electrostatic surface charge, only a single copy from a single exposure is possible.
  • Walkup U.S. Pat. No. 3,251,706 discloses an electrostatic process in which a copy sheet or web is applied to a photoconductive surface after formation of an electrostatic image thereon. Toner is applied to the copy sheetand, after the sheet is removed from the photoconductive surface, the toner is fused to the sheet. The photoconductive surface retains the xerographic electrostatic latent image.
  • the present invention provides an electrostatic process which overcomes the foregoing drawbacks and which enables the production ofa plurality of copies on plain" copy paper.
  • the process also permits the production of full color reproduction in which two, three or more toner colors are overlayed onto a single copy sheet.
  • lnexpe'nsive photoconductive materials can be used, such as zinc oxide, as well as the traditional selenium or cadmium sulfide surfaces.
  • an insulative, non-photoconductive surface may be used. lmportantly, the image carrying surface is completely protected from the abrasive effects of toner application and therefore has an extremely long lifetime.
  • any means for developing the image such as differential melting, dimpling by heat, and the like, may be used.
  • the present invention utilizes inductive electrophotography in which an insulating film overlies an electrostatic image carrying surface and involves a unique combination of insulating film properties, charging levels and other process conditions to develop an image, as with toner or otherwise, while retaining an electrostatic latent image on the image carrying surface.
  • an insulating film overlies an electrostatic image carrying surface and involves a unique combination of insulating film properties, charging levels and other process conditions to develop an image, as with toner or otherwise, while retaining an electrostatic latent image on the image carrying surface.
  • toner when toner is deposited directy on the charged photoconductor surface, some charge is lost directly to the toner.
  • the interposition of a thin insulating film as described below, prevents loss of charge.
  • a thin insulative member such as a plastic film, is applied in direct contact with an insulative surface which may be photoconductive and which may be adapted for having an electrostatic image formed thereon.
  • a photoconductive surface When using a photoconductive surface, it is initially electrostatically charged to a predetermined potential which is sufficient to effect development of an image on the insulating film but which is insufficient to discharge when the image is removed from the photoconductive surface. Before or after application of the insulating film the charged photoconductive surface is exposed to a pattern of radiation to form a latent electrostatic image of the pattern on the photoconduetive surface.
  • an electrostatic image is placed directly thereon by means of an electron beam or by a charged stylus, or the like. If toner is used as the developing agent, it can be applied while one surface ofthe insulating film is in direct contact with the image carrying surface, adhering to the opposite surface by induction.
  • the toner may be transferred and this can occur while the insulating film is in contact with the photoconduetive surface.
  • the insulating film is separated from the image carrying surface and the toner image is fused to the film or is transferred to a support member, such as copy paper, and then fused to the paper. Since the electrical field at the image carrying surface is insufficient to cause discharge upon separation of the insulating film, the latent image can be reused by reapplying the same insulating film or by applying a fresh length of insulating film. Neither further charging nor further exposure-is required to produce another toner image on the free surface of the insulating film.
  • the insulating film can be in the form of a closed loop and the image carrying surface carried by a drum so that a plurality of copies can be continuously formed.
  • the circumference ofthe drum is equal to the length of one document, copies are produced continuously as the drum rotates and the endless loop continues to advance. If the drum circumference has a length equivalent to a plurality of documents, or if a belt or other suitable configuration of the image carrying medium is provided having such length, after one charge and exposure for each page, copies of a document of plural pages are produced in sequence.
  • exposure ofeach segment can be effected with successively different wavelengths of radiation and a different colored toner applied to each segment of insulating film in synchronization with rotation of the drum.
  • the same copy sheet is repeatedly brought into successive contact with each segment for successive transfer of the differently colored toner images to a single sheet to thereby provide a full color reproduction of the document.
  • the insulating film can constitute the final copy which may be either transparent or opaque.
  • the thin insulating film can be laminated to another material for support and/or to protect the image.
  • the thin insulating film should be a good electrical insulator, and be smooth. uniform and thin. Additionally, for reuse, the film should be dimensionally stable, highly abrasion and wear resistant and thermally stable. It is critical that the film be in intimate contact with the image carrying surface so that there is virtually no space between the insulating film and photoconduetive surface.
  • the insulating film should have high lateral electrical resistivity to prevent image spread. at least about 10" ohms/ [10f surface, and a maximum thickness of about 3.0 mils, preferably about l.5 mils, to allow acceptable resolution and density of the toner image.
  • Photoconductive media composed of sensitized photoconduetive particles dispersed in a polymeric matrix can be controlled to give extremely low decay rates, as can evaporated amorphous selenium, enabling the production ofa multiplicity of high quality copies.”
  • FIG. I is a diagrammatic view of a mechanism for ac complishing one embodiment of the invention.
  • FIG. 2 is a diagrammatic view of an alternate toner transfer mechanism
  • FIG. 3 is a diagrammatic view of another alternative toner transfer mechanism
  • FIG. 4 is a diagrammatic view of a mechanism for accomplishing an alternative embodiment of the invention wherein a plural colored copy is produced;
  • FIG. 5 is a diagrammatic, partial view of a mechanism utilizing an electron beam to provide an electrostatic image
  • FIG. 6 is a diagrammatic, partial view of a mechanism utilizing a charged stylus to provide an electrostatic image:
  • FIG. 7 is a set of curves relating film thickness and mean toner particle size to resolution.
  • FIG. I one embodiment of the invention is illustrated.
  • the drawing is schematic and serves to illustrate the process steps. Therefore, relative sizes and positions are not to be taken literally but are used as convenient to ease of illustration.
  • the toner transfer station is shown in the drawing as vertically spaced a substantial distance from the photoconduetive drum surface, whereas in actual construction it 'would be located as close to the drum as practical and mitting material, which will be described hereinafter in more detail, is overlaid on a portion of photoconductive surface and is held in direct close contact with the photoconductive surface 10 by means of suitable tensioning means (not shown) operative with various rollers as required for subsequent operations.
  • the belt 18 is led over a rubber transfer roller 20 and from there to a pair of idler rollers 22 and 24 into a tank 26 containing a cleaning liquid 28, as hereinafter described, onto an idler roller 30 within the tank and from there over an idler roller 32, past a heater 34 and back onto the photoconductive surface 10 of the drum 14.
  • the drum l4 and belt 18 travel in a counterclockwise direction and a corona charging grid 36 is disposed adjacent the photoconductive surface 10 at a point prior to its contact with the belt 18.
  • a discharge lamp 38 is disposed at a position prior to the disposition of the corona charging grid 36 and subsequent to separation of the belt 18 from the photoconductive surface 10, all with respect to the direction of travel of the belt 18 and drum 14.
  • a document exposure station 40 is disposed to overlie a contact region of the belt 18 and photoconductive surface 10 and is followed in the course of travel of the drum by a toning station 42 which is also disposed adjacent a contact region between the belt 18 and photoconductive surface 10.
  • the exposure station 40 is constructed in accordance with any of a number of various types of exposure stations utilizing direct exposure through a document, reflection exposure utilizing mirrors or counterdirected exposure lamps, image forming lenses, inversion' lenses, and the like as appropriate to a particular configuration as might be desired, and such components do not form a part of the present invention as such.
  • a document 44 to be reproduced is placed face down on a glass plate support 46 and illumination lamps 48 are disposed beneath the plate 46 to direct exposure radiation through the plate 46 against the document 44.
  • the plate support 46 is movable, as indicated by the arrow 49, in the opposite direction to travel of the drum (or the same direction with an appropriate speed differential) to' expose the drum surface to the entire document.
  • the toning station 42 can have any prior art configuration, and it is found advantageous to utilize a A magnetic brush 52 which is operative with a bin 54 carrying a supply of toner particles 56 closely adjacent a contact region between the photoconductive surface 10 and belt 18.
  • the photoconductive drum surface 10 is uniformly charged by means of the corona charging grid 36 and is thereafter directly exposed and toned, toner particles adhering directly to the photoconductive surface. Thereafter, the toner particles are transferred to a paper sheet or the like.
  • the photoconductive surface is then recharged, exposed to a different document, or the same document, and again toned and the toner again transferred.
  • the present mechanism differs from prior mechanisms in that once the photoconductive drum surface 10 is charged and exposed, it need not thereafter be charged or exposed until it is desired to reproduce a different document.
  • the counterclockwise movement of the drum and belt continues without further charge and exposure, but with subsequent toning and toner transfer steps so as to produce a plurality of images from a single charge and exposure.
  • the discharge lamp 38 is activated to blanket expose the drum surface and the charging grid 36 and exposure station 40 are again actuated.
  • a control unit 57 which serves to synchronize operation of thedischarge lamp 38, corona charging grid 36 and exposure station 40, as indicated by the arrows 59, 61, 63 and 65, respectively, to deactivate these components after the initial exposure and activate them again after the desired number of copies have been produced and it is desired to reproduce a different document.
  • the control unit 57 deactivates the charging grid 36 and exposure lamps 48 after such a plurality of exposures have been made. Initially, the corona charging grid 36 is actuated to place a uniform electrical charge over the entire photoconductive surface 10.
  • the photoconductive surface 10 can be charged negatively, as indicated at 58 by the negative signs, or it may be charged positively, depending on the photoconductor, all as well known.
  • the drum and belt rotate the charged photoconductive surface 10 is brought into intimate direct contact with the belt 18 and while in such contact rotates past the exposure station 40.
  • the exposure station is actuated so as to illuminate the photoconductive surface 10 through the belt 18, dissipating chargesv at exposed regions, as well known to the art, thereby imparting a pattern of charges as a latent image of the document to be reproduced.
  • the drum l4 and belt 18 rotate past the exposure station, the exposed region is contacted by the magnetic toner brush 52 which deposits particles of toner onto the surface of the belt 18 immediately overlying the latent electrostatic image.
  • the toner is attracted to the belt 18 as a result of induced electrostatic forces through the belt and forms a toner image of the document on the belt 18.
  • the belt 18 can be then separated from the drum surface 10 and may be led with its toner image, as indicated at 60, to a toner transfer station 62.
  • the conductive roller 20 compresses the toner bearing belt 18 into contact with a support sheet 64 which is sandwiched between the belt 18 and a metallic roller 66.
  • the support sheet 64 can be a paper sheet or any desired support member to which a toner image will adhere.
  • the metal roller 66 is formed with an axially central heating rod 68, heated by means of a power source shown diagrammatically at 70, so that heat is applied through the support sheet 64 to fuse the toner thereto.
  • the support sheet 64 is fed from a supply 72 thereof by means of a pressure roller 74 actuated in registration with travel of the belt 18 by a mechanism not shown. As the toner image is transferred, the support sheet 64 passes onto a conveyor belt 76 and from there into a receptacle 78..
  • the belt 18 and drum 14 continue to rotate bringing the previously toned portion of the belt 18 back into engagement with the photoconductive drum surface 10. Since the discharge lamp 38 and corona charging grid 36 have been deactivated, the photoconductive surface 10 retains the electrostatic latent image and as the belt and drum are rotated in contact past the toner station 42, the toner 56 is again applied to the belt 18, adhering to the belt 18 as before as a result of induced electrostatic forces from the latent electrostatic image on the photoconductive surface 10. Thereafter, as the belt passes through the toner transfer station 62, another copy of the document 44 is obtained by transfer of toner from the belt 18 to another support sheet.
  • Photoconductive material can be utilized in which sensitized photoconductive particles are dispersed in a polymeric matrix to give extremely low dark decay rates.
  • sensitized photoconductive particles can be dispersed in a polymeric matrix to give extremely low dark decay rates.
  • about 80 weight percent of photoconductive zinc oxide can be dispersed in a silicone resin sold under the trademark SR-82 and coated as a layer on a drum and will have sufficiently low dark decay rate to enable the reproduction of about 20-50 copies of good quality from a single exposure.
  • Specific compositions and dark decay rates are well known and reference can be made to prior issued patents such as cited above.
  • discharge lamp 38 and corona charging grid 36 are se-' quentially actuated by the control, theexposure lamp 38 blanket exposing the photoconductive surface 10 to remove the electrostatic latent image and the corona charging unit 36 placing a uniform electrostatic charge over the photoconductive drum surface.
  • the control thereafter actuates the document exposure lamp 48 to form an electrostatic latent image of the new document through the belt 18 onto the photoconductive surface 10.
  • the potential to which the photoconductor is charged be limited to a voltage level which is insufficient to initiate charge transfer ,or discharge between the photoconductive surface 10 and the insulating belt .18.
  • the maximum potential across the photoconductive layer which will avoid charge transfer to the belt 18 depends upon the relative capacitances of the photoconductive layer and the belt 18, which forms a capacitive voltage divider.
  • the insulating belt 18 be maintained in intimate contact with the photoconductive surface 10, have a high lateral electrical resistivity, at least 10"" ohms/B of surface, to prevent image spread and have a maximum thickness of about 3 mils so as to enable satisfactory resolution and density of toner image.
  • Exemplary materials include thin insulating films formed of polycarbonates, polyphenylene oxides, polysulfones, Mylar (a transparent polyethylene terephthalate polyester film), polypropylene, Teflon (a polyfluoro hydrocarbon), Kapton (a polyimide), polyethylene, and the like.
  • the belt 18 should be transparent at least to the imaging radiations.
  • color separation images can be provided by form-' ing adjacent sections of the belt 18 with different sepa-' ration colors and this is particularly useful when the photoconductive surface 10 has an effective length equal to three or four documents.
  • the toner images can be overlaid to yield a composite, full color image.
  • the successive images can be transferred to a single transparent or opaque sheet utilizing a toner transfer mechanism as will be described hereinafter with respect to FIG. 4.
  • toner transfer station 62 in place of a toner transfer station 62, one can employ a non-reusable belt of thin insulating film and lead the toned film to a fusion station whereat the toner is fused to the insulating film to form a final, permanent copy.
  • the principles of this invention are applicable to the preparation of images utilizing a flat photoconductive surface and/or the utilization of a consumable insulative film.
  • the insulative film can be fed from a supply roller and taken up by a take up roller and thereafter discarded or reused.
  • Such a configuration can be utilized with either a flat photoconductive surface or a drum surface.
  • the cost of the thin insulative film is sufficiently small as to make such consumption a practicality.
  • the insulating film 18 may or may not need to be subjected to a cleaning step.
  • the belt 18 can be reapplied without any cleaning step, in which case the belt 18 can be led directly over the idler roller 32, bypassing the tank 26, as shown by the dashed line 82. In such case, the heater 34 would be disconnected. lf it is desired to clean the belt 18, it is simply led into the cleaning tank 26 whereupon it is contacted with a cleaning liquid such as Freon TA.
  • the cleaning liquid may be conductive so as to dissipate random electrostatic charges which may be present on the belt 18.
  • a small rotating brush 84 is supported within the conductive liquid 28 in contact with the toner carrying surface of the belt 18 to aid in dislodging any toner which may have remained adhered to the belt 18.
  • FIG. 2 there is diagrammatically illustrated an alternative toner transfer mechanism wherein-the copy paper is slightly wetted by a toner transfer solvent and thereafter brought into contact with the toned belt surface.
  • the belt 18' is led from the toning station 42 and pressed by a rubber roller 86 into contact with a copy sheet 88 against a metal roller 90.
  • the copy sheet 88 is fed from a supply 92 thereof by means of a feed roller 94 rotating in synchronization with travel of the belt 18'.
  • As the copy sheet 88 is fed toward the belt 18*, it passes between a platen 96 and an opening 97 in a solvent supply tank 98 containing a solvent 100.
  • the solvent 100 is released via a check ball 102 to lightly wet the top surface of the copy sheet 88.
  • the relative disposition of the solvent tank 98 and platen 96 can be adjusted by a mechanism not shown to adjust the amount of wetting.
  • solvent one can utilize acetone, tetrahydrofuran, methylene chloride, or
  • the toner adheres to the wetted copy sheet 88 as it passes into contact with the belt 18.
  • the solvent is sufficiently volatile to completely dry while being conveyed via the conveyer belt 76 to the bin 78.
  • FIG. 3 another alternative toner transfer mechanism is illustrated wherein the toned belt 18" is led from the toning station 42 and pressed by a conductive rubber roller 104 into contact with a copy sheet 106, fed from a supply not shown, against a grounded metal roller 108.
  • a potential is established between the conductive rubber roller 104 and metal roller 108 by a voltage source 110 andground connections, the voltage source 110 and roller ground being connected by brushes not shown.
  • a positive voltage is applied to the conductive rubber roller 104 to repel the positively charged toner particles onto the copy sheet 106. Thereafter the toner particles are fused to the copy sheet 106 by passage through a heater, not shown.
  • FIG. 4 there is illustrated a mechanism in diagrammatic form for applying successive different colored toner images onto a single copy sheet.
  • photoconductive surface 112 is carried on the conducloop or belt 120 is applied to the drum in a manner which may be identical with the application of the belt 18 tothe'drum 14 as illustrated in FIG. 1.
  • the drum 116 and belt 120 rotate counterclockwise in registration in the same manner as described in FIG. 1 so that a uniform electrostatic charge can be placed on the surface" of the photoconductive layer 112 by a corona charging grid 122 and erased by a discharge lamp 124.
  • the photoconductive surface 112 is rotated into close contact with the belt 120 so that region A enters an exposure station 126.
  • image forming radiation from exposure lamps 129 passes through associated lenses, indicated at 128.
  • a support plate 133 for a document 135 to be copied, is movable as indicated by arrow 130 in synchronization with rotation of drum 116, which, with the .lamp 128, is regulated by'a control unit 132, as described with respect to the similar mechanism inFlG. l.
  • the imaging radiation then passes through a selective color absorber 131 and through the belt 120 to impinge onto the photoconductive surface 112, selectively discharging the photoconductive surface 112 in the region A in accordance with the image pattern.
  • the color absorber 133 is shown diagrammatically as a sheet 133 of plastic film, such as Mylar, coated with color absorbing dye and fed from a feed roller 134 to a take up roller 136.
  • the filter sheet 133 is formed with successively adjacent differently colored portions in correspondence to well known color separation criteria, each portion having a length corresponding to a document length and marginal region 118.
  • the sheet 133 is formed with a leader which is followed by an initial transparent portion so as to provide a background black image.
  • the next succeeding portion transmits red light followed by a portion which transmits yellow light and followed by a portion adjacent a trailer which transmits blue light.
  • the feed and take up rollers 134 and 136 are actuated by the control 132 so that after the last, bluetransmitting portion has passed the exposure station 126, the sheet 133 is rapidly rewound for the next copy.
  • the marginal distance between the last photoconductive region Dand the first photoconductive region A, as indicated at 138, is sufficiently large to accommodate a rapid rewinding of the color separation sheet 133.
  • Other exposure mechanisms and color separation mechanisms can be utilized as desired, the foregoing mechanism illustrating only a particular means for accomplishing color separation.
  • the belt can itself be formed of successively differently absorbing portions.
  • the length of the belt 120 would be a multiple of the circumferential length of the drum, a multiple of two being convenient to accommodate the corona charging grid 122 and discharge lamp 124.
  • toner applicators 140, 142, 144 and 146 are brought into operative association with the belt 122 so that the toner contained therein can be applied to the belt 120 by inductive electrostatic attraction.
  • the toner applicators 140, 142, 144 and 146 are movable into and out of operational contact with the belt 120, as indicated by the arrows, in accordance with a selection signal generated by the control 132 as indicated by the line 148.
  • The. toner applicators contain differently colored toners in accordance to the color of exposure radiation passing through the filtersheet 133 and their actuation is selected by the control unit 132.
  • the toner applicator 140 contains black toner particles and is applied to the belt -120 overlying the exposed photoconductor surface region A.
  • Toner applicators 142, 144 and 146 contain respectively red, green and blue toner particles and are successively applied to the belt 120 as the successive regions B, C and D are rotated with the belt past their respective locations.
  • the belt 120 carrying the toner particles from the applicator 140 passes to a toner transfer station 150 where it is pressed by means of a rubber roller 152 into contact with a copy sheet 154 against the outer surface of a transfer drum 156.
  • the transfer drum is formed generally hollow with a plurality of openings 158 through its surface.
  • a vacuum source, indicated at 160 is applied interiorly of the drum 156 to cause adherence of the copy sheet 154 to the surface of the drum 156.
  • Thevacuum source 160 is then actuated by the control unit 132 as indicated by the line 162 as the copy sheet 154 is fed from a supply 164 thereof.
  • copy sheets are supplied by any mechanism known to the art, e.g., a gripping roller 166 and which rotates in registration with the drum 116 so that a copy sheet 154 is fed once for each complete rotation of the drum 116.
  • the vacuum source 160 is maintained operative until the last toner image, representing the latent image on photoconductive region D, is transferred to the copy sheet 154.
  • the control unit 132 opens the drum 156 to atmospheric pressure, allowing the belt 120 to carry the copy sheet onto a bridging platen 170 and from there on to a conveyor belt 172 to deposit the copy in a receptacle 174.
  • the control 132 successively actuates the discharge lamp 124, corona charging unit 122 and exposure lamp assembly 126.
  • a belt cleaning station 176 can be provided which is identical to the components described with re spect to FIG. 1.
  • FIG. 5 there is illustrated still another embodiment wherein in place of a photoconductive surface, one uses a surface 178 of insulative mate- .rial, which for convenience, can be carried by a drum 180.
  • An electrostatic image as desired is placed on the insulative surface 178 by means of an electron beam 182 generated by any mechanism 184 as known to the prior art as determined by a control 186.
  • the drum 180 rotates the surface 178 into close contact with a belt 188 of thin insulative material which may be identical with the belt 18 of FIG. 1, but need not be transparent Toner 189 is applied to the belt 188 and transferred in a manner as described with respect to FIG. 1.
  • the belt 188 is shown as consumable and as carrying an image fused thereon by heaterl90.
  • FIG. 6 there is illustrated an embodiment wherein an electrostatic image as desired is placed on a surface 192 of insulative material by means of a charged stylus 194 as determined by a control 196.
  • the surface 192 is rotated into close contact with a belt 198 of thin insulative film and toner 200 is applied and transferred as referred to with respect to FIG. 5.
  • EXAMPLE 1 Commercially available zinc oxide paper was charged negatively with a commercially available corona charging unit to a dark potential of 550 volts and selectively, image-wise discharged by light exposure. A sheet of 0.5 mil smooth Mylar was placed in intimate contact on the zinc oxide sheet. The Mylar sheet was toned with Hunt 67-146F toner having a mean particle size of about 9 microns, employing a hand-held magnetic brush toner applicator, which also served to assure close, intimate contact of the Mylar sheet and zinc oxide paper. In order to determine resolution, the toner was fused to the Mylar sheet by heating on a hot plate at about 125C for a few seconds to yield a copy having a resolution of about l3 line pairs per millimeter.
  • microns was utilized on 2 mils, 1 mil, 0.5 mil and 0.25 mil Mylar, respectively, to obtain copies having resolutions of 4, 6, 9 and I6 line pairs per millimeter.
  • Example II The procedure of Example I was followed except that Hunt 67-146 toner, having a mean particle size of about l6 microns, was utilized on 2 mils, l mil, 0.5 mil and 0.25 mil Mylar, respectively, to obtain copies having resolutions of 4.5, 7, 9 and l 1.3 line pairs per millimeter, respectively.
  • Example 13-16 The procedure of Example l was followed except that a modified zinc oxide paper (which accepts positive charges) was employed and a positive charge was applied with the corona charging unit.
  • Xerox microxerographic toner having a mean particle size of about 3.5 microns was applied with a powder cloud developer on 2 mils, 1 mil, 0.5 mil and 0.25 mil Mylar to obtain copies having resolutions of about 7, 1 l, 14 and 18 line pairs per millimeter, respectively.
  • Example 17 The procedure of Example 1 was followed except that 2 mils and l milGeneral Electric Lexan (a polycarbonate) was utilized to obtain copies having resolutions of 5 and 10 line pairs per millimeter, respectively.
  • the film can be used directly as transparencies or for overhead projection, or may be laminated to another material support and/or protection. Also, as above indi-' cated, development mechanisms not using toner can be utilized such as differential wetting with subsequent lithographic-type duplicating and heating the thin insulating film while on the charge bearing surface to dimple the film in areas of electrostatic charge followed by cooling to freeze theimage. The latter process is particularly applicable to certain, known heat resistant photoconductive surfaces and to other charge bearing surfaces.
  • the invention also contemplates the use of a tonerimaged thin insulating film as a master substrate in a further duplication process in which the toner image may be transferred in whole or in part to another surl3 face.
  • the toner particles can include alcohol soluble dyes for use in a subsequent spirit duplication process.
  • a process for electrostatic reproduction comprising a series of initial steps, including a charging step and an image-forming step, and a subsequent plurality of said series omitting said charging and image-forming steps, to produce a plurality of reproduction copies, said initial steps and plural series being conducted with a single thin insulative member, said initial series of steps comprising:
  • said thin insulative member in direct contact with a photoconductive surface adapted for having an electrostatic image formed thereon, said thin insulative member having a thickness of about 0.1 mil to about 3.0 mils and a resistivity of at least ohms/[10f surface; electrostatically charging said photoconductive surface, as said charging step, prior to application of said thin insulative member; exposing a predetermined region of said charged photoconductive surface, as said image-forming step, to a pattern of radiation to form an electrostatic charge image of said pattern on said photoconductive surfaee'region; thereafter, developing said electrostatic image on said thin insulative member by applying toner thereto to form a toner image thereon while said thin insulative member is in said direct contact;
  • said insulative member includes a length in excess of the length of said predetermined region and wherein said series of initial steps includes the steps of forming a further electrostatic image on a region of said charge bearing surface lateral of said first mentioned region, applying said excess length of insulative member in direct contact with said lateral region subsequent to said further electrostatic image formation thereafter developing said further electrostatic image on said thin insulative member, and carrying said further image away from said electrostatic charge attraction.
  • said insulative member comprises a film formed of plastic having a thickness of from about 0.25 mil to about 1.5 mils.
  • cent portions of said'photoconductive surface prior to application of a corresponding insulative member portion thereto successively exposing adjacent charged portions of said photoconductive surface to form successive electrostatic images, successively applying further toner to said adjacent insulative member portions subsequent to exposure of corresponding portions of said photoconductive surface and while in direct contact with said photoconductive surface to form successive toner images, and successively transferring said toner images to one or more support members.
  • said insulative member includes a length in excess of the length thereof applied to said photoconductive surface in said initial steps and wherein at least one of said plurality of series of steps is conducted on said excess length.
  • a process for electrostatic reproduction comprising a series of initial steps, including an imageand asubsequent plurality of said series omitting said image-forming step, to produce a plurality of reproduction copies, said initial steps and plural series being conducted with a single thin insulative member, said initial series of steps comprising:
  • a thin insulative member having a thickness of about 0.1 mil to about 3.0 mils and a resistivity of at least 10" ohms/[10f surface, with a surface thereof in direct contact with said charge bearing surface region;
US00215873A 1972-01-06 1972-01-06 Method and apparatus for inductive electrophotography Expired - Lifetime US3820985A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
US00215873A US3820985A (en) 1972-01-06 1972-01-06 Method and apparatus for inductive electrophotography
GB5605872A GB1403218A (en) 1972-01-06 1972-12-05 Method and apparatus for electrostatic reproduction
CA159,713A CA990339A (en) 1972-01-06 1972-12-21 Method and apparatus for inductive electrophotography
DE2263903A DE2263903A1 (de) 1972-01-06 1972-12-28 Verfahren und vorrichtung zur elektrofotografie
IT33665/72A IT972987B (it) 1972-01-06 1972-12-28 Metodo ed apparecchio per l elet trofotorrafia induttiva
JP48004542A JPS4879641A (de) 1972-01-06 1972-12-29
AU50723/73A AU5072373A (en) 1972-01-06 1973-01-03 Electrophotography
FR7300433A FR2167790B1 (de) 1972-01-06 1973-01-05
US05/445,377 US3937572A (en) 1972-01-06 1974-02-25 Apparatus for inductive electrophotography

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US00215873A US3820985A (en) 1972-01-06 1972-01-06 Method and apparatus for inductive electrophotography

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JP (1) JPS4879641A (de)
AU (1) AU5072373A (de)
CA (1) CA990339A (de)
DE (1) DE2263903A1 (de)
FR (1) FR2167790B1 (de)
GB (1) GB1403218A (de)
IT (1) IT972987B (de)

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3924945A (en) * 1974-12-03 1975-12-09 Xerox Corp Apparatus for inductive imaging with simultaneous polar ink development
US3927934A (en) * 1974-03-11 1975-12-23 Xerox Corp Electrostatographic reproduction machines
US4021106A (en) * 1973-03-21 1977-05-03 Bell & Howell Company Apparatus for electrostatic reproduction using plural charges
US4025188A (en) * 1974-11-25 1977-05-24 Xerox Corporation Photoactive device for xerography
US4027964A (en) * 1972-11-27 1977-06-07 Xerox Corporation Apparatus for interposition environment
US4049344A (en) * 1975-03-10 1977-09-20 Xerox Corporation Electrostatic imaging system
US4115114A (en) * 1972-09-21 1978-09-19 La Cellophane Electrostatic charge image transfer
US4188110A (en) * 1978-04-03 1980-02-12 Xerox Corporation Photoconductive belt supporting apparatus
US4199356A (en) * 1974-02-01 1980-04-22 Mita Industrial Company Limited Electrophotographic process, of transferring a magnetic toner to a copy member having at least 3×1013 ohm-cm resistance
US4204731A (en) * 1977-02-04 1980-05-27 Agfa-Gevaert, A.G. Apparatus for electrophotographic copying with means for effecting image penetration through the copy carriers
EP0074677A1 (de) * 1981-08-19 1983-03-23 Océ-Nederland B.V. Verfahren und Vorrichtung zur Übertragung und Fixierung von pulverförmigen Tonerbildern
US4533611A (en) * 1982-04-29 1985-08-06 Hoechst Aktiengesellschaft Process for preparing a planographic printing plate
US4545669A (en) * 1984-02-21 1985-10-08 Xerox Corporation Low voltage electrophotography with simultaneous photoreceptor charging, exposure and development
US4899197A (en) * 1988-05-17 1990-02-06 Colorocs Corporation Fuser for use in an electrophotographic print engine
US4987455A (en) * 1989-11-22 1991-01-22 Eastman Kodak Company Multicolor imaging apparatus
US4994858A (en) * 1989-11-22 1991-02-19 Eastman Kodak Company Electrostatographic apparatus for forming multicolor images on a receiving sheet
EP0464804A2 (de) * 1990-07-03 1992-01-08 Oki Electric Industry Co., Ltd. Elektrophotographisches Verfahren und Gerät
US5229235A (en) * 1988-06-27 1993-07-20 Sony Corporation Electrophotographic process using melted developer
US5298945A (en) * 1991-09-20 1994-03-29 Sharp Kabushiki Kaisha Electrophotographic printing machine

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2535572A1 (de) * 1974-08-29 1976-03-11 Xerox Corp Neue xerografische systeme und verfahren zur verbesserung der haltbarkeit und lebensdauer solcher systeme
JPS5381121A (en) * 1976-12-27 1978-07-18 Kip Kk Method of taking electrophotography and device therefor

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4115114A (en) * 1972-09-21 1978-09-19 La Cellophane Electrostatic charge image transfer
US4027964A (en) * 1972-11-27 1977-06-07 Xerox Corporation Apparatus for interposition environment
US4021106A (en) * 1973-03-21 1977-05-03 Bell & Howell Company Apparatus for electrostatic reproduction using plural charges
US4199356A (en) * 1974-02-01 1980-04-22 Mita Industrial Company Limited Electrophotographic process, of transferring a magnetic toner to a copy member having at least 3×1013 ohm-cm resistance
US3927934A (en) * 1974-03-11 1975-12-23 Xerox Corp Electrostatographic reproduction machines
US4025188A (en) * 1974-11-25 1977-05-24 Xerox Corporation Photoactive device for xerography
US3924945A (en) * 1974-12-03 1975-12-09 Xerox Corp Apparatus for inductive imaging with simultaneous polar ink development
US4049344A (en) * 1975-03-10 1977-09-20 Xerox Corporation Electrostatic imaging system
US4204731A (en) * 1977-02-04 1980-05-27 Agfa-Gevaert, A.G. Apparatus for electrophotographic copying with means for effecting image penetration through the copy carriers
US4188110A (en) * 1978-04-03 1980-02-12 Xerox Corporation Photoconductive belt supporting apparatus
EP0074677A1 (de) * 1981-08-19 1983-03-23 Océ-Nederland B.V. Verfahren und Vorrichtung zur Übertragung und Fixierung von pulverförmigen Tonerbildern
US4533611A (en) * 1982-04-29 1985-08-06 Hoechst Aktiengesellschaft Process for preparing a planographic printing plate
US4545669A (en) * 1984-02-21 1985-10-08 Xerox Corporation Low voltage electrophotography with simultaneous photoreceptor charging, exposure and development
US4899197A (en) * 1988-05-17 1990-02-06 Colorocs Corporation Fuser for use in an electrophotographic print engine
US5229235A (en) * 1988-06-27 1993-07-20 Sony Corporation Electrophotographic process using melted developer
US4987455A (en) * 1989-11-22 1991-01-22 Eastman Kodak Company Multicolor imaging apparatus
US4994858A (en) * 1989-11-22 1991-02-19 Eastman Kodak Company Electrostatographic apparatus for forming multicolor images on a receiving sheet
EP0464804A2 (de) * 1990-07-03 1992-01-08 Oki Electric Industry Co., Ltd. Elektrophotographisches Verfahren und Gerät
EP0464804A3 (en) * 1990-07-03 1992-02-12 Oki Electric Industry Co., Ltd. Electrophotographic process and apparatus
US5148225A (en) * 1990-07-03 1992-09-15 Oki Electric Industry Co., Ltd. Electrophotographic process and apparatus
US5298945A (en) * 1991-09-20 1994-03-29 Sharp Kabushiki Kaisha Electrophotographic printing machine

Also Published As

Publication number Publication date
CA990339A (en) 1976-06-01
FR2167790B1 (de) 1977-04-22
DE2263903A1 (de) 1973-07-12
JPS4879641A (de) 1973-10-25
IT972987B (it) 1974-05-31
GB1403218A (en) 1975-08-28
AU5072373A (en) 1974-07-04
FR2167790A1 (de) 1973-08-24

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