EP0056313A2 - Procédé à copier électrophotographique - Google Patents

Procédé à copier électrophotographique Download PDF

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Publication number
EP0056313A2
EP0056313A2 EP82300091A EP82300091A EP0056313A2 EP 0056313 A2 EP0056313 A2 EP 0056313A2 EP 82300091 A EP82300091 A EP 82300091A EP 82300091 A EP82300091 A EP 82300091A EP 0056313 A2 EP0056313 A2 EP 0056313A2
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EP
European Patent Office
Prior art keywords
paper
copy paper
document
charging
sheet
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP82300091A
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German (de)
English (en)
Other versions
EP0056313A3 (fr
Inventor
John Michael Payne
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
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Individual
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Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP0056313A2 publication Critical patent/EP0056313A2/fr
Publication of EP0056313A3 publication Critical patent/EP0056313A3/fr
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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

Definitions

  • This invention concerns electrophotographic copying and in particular an improved copying medium on which electrophotographic copies can be made, an improved method of producing such copies based on a reflex exposure technique and apparatus for performing the improved method.
  • Electrophotographic copying using a so-called reflex exposure technique is known.
  • a sheet of paper having one face coated with a photoconductive medium such as zinc oxide is initially charged electrostatically so that the coated surface bears a relatively uniform electric charge and the charged surface is then located in contact with a document to be copied.
  • Light is shone through the charged paper for a controlled period of time and the relatively uniform electric charge on the sheet of copying paper is converted into an electrostatic charge pattern corresponding to the inverse of the printing on the document.
  • This electrostatic pattern can either be transferred to another sheet of similarly coated paper so as to produce a right facing electrostatic pattern for subsequent development using finely divided toner in liquid suspension or as a fine powder.
  • the original sheet of paper bearing the inverted electrostatic image can itself be developed using conventional toner in liquid form or as a dry powder and the resulting inverted copy used as a new master in place of the document in a second and similar stage to the overall process. If care is taken the overall result using the two stage reflex process is almost equivalent to that in which the electrostatic charge is transferred and its only disadvantage is one of speed in that it is usually twice as long and in its double consumption of consumables unless the first image is formed on a re-usable plate or drum in place of the first sheet of paper.
  • the present invention seeks to provide an improved method of photocopying based on an improved paper by which a right facing copy can be produced using a reflex technique involving only a single stage of charging exposure and development.
  • the resulting method has thus all the advantages of reflex copying coupled with the advantages of speed and minimal consumption of consumables associated with drum and plate exposure techniques hitherto known.
  • U.K. Patent Specification 995491 discloses an electrostatic recording material comprising an insulating dielectric layer, typically of zinc oxide (although other dielectric materials are specified) and as a support therefore, a GLASSINE-type or'modified GLASSINE-type paper.
  • Modification of such paper is by the addition of fillers and/or dyes to reduce the transparency of the paper.
  • sodium silicate to such paper is also described, for the purpose of increasing the uniformity of conductivity through the paper and to improve its mechanical strength,surface smoothness and density.
  • the present invention starts from this known state of the art and provides an improved method and apparatus for producing a right facing copy and an improved paper for use in such a method and apparatus.
  • copy paper is intended to mean any sheet or film substrate carrying an appropriate chemical coating of a dielectric photo- conductive material and capable of being employed in electrophotographic processes such as described herein.
  • the expression is not intended to be limiting to materials which are conventionally throught of as papers but is intended to include any plastics or paper or film or fabric or composite thereof.
  • the paper may be in the form of separate sheets or on a roll from which it is drawn off as required.
  • a preferred material for the substrate is a paper manufactured by Wiggins Teape Limited and sold under the Trade Name GLASSINE.
  • GLASSINE A preferred form of this material is so-called bleached GLASSINE type N802.
  • the substrate may have to possess an electrical resistance which bears some relationship to the resistance of the photoconductive film applied thereto and/or to the process of charging which is to be employed in the method to be described.
  • the resistivity of the substrate material should be high although experiments have led to the applicant to believe that materials having lower resistivities than GLASSINE can still be employed provided certain measures are taken in the method of use to be described.
  • the substrate may to advantage be selected so as to have the smallest possible weight per unit area consistent with the strength etc., of the required copy. Satisfactory results have been obtained using 37 gram GLASSINE paper and it is believed that lower weight papers could be used if required.
  • a method of producing a right facing electrophotographic copy comprises the steps of:-
  • the charge induced thereon is preferably of positive polarity.
  • the toner may be dispersed in a liquid suspension or may be in the form of a dry powder.
  • the copy paper during charging, is located adjacent a conductive surface which itself is electrically insulated from its surroundings (including earth) and one side of the source of high potential used to create the field for charging the photoconductive layer, is connected to a charging electrode, spaced from the paper, and the other side is connected via a high resistance link to the conductive plate.
  • the charging electrode may be a wire.
  • the value of the high resistance link may be established by experiment. Where the substrate is GLASSINE and the photocohductive material is zinc oxide, good results have been obtained using a resistance of 200 Megohms.
  • the rear, uncoated, face of the substrate may be electrically insulated from the conductive plate by a thin layer of insulating material. This may for example be in the form of a separate sheet or film between the paper and the plate.
  • the substrate requires the use of an insulating sheet between it and the conductive plate, during charging, it has been found that after a succession of charges, the insulating sheet becomes charged itself to an extent sufficient to inhibit further useful charging of copy paper placed thereon. To this end the insulating sheet must itself be replaced or discharged if the imaging efficienty of the arrangement is to be maintained.
  • the insulating sheet may be an endless belt of plastics material or the like and the belt is discharged by moving it around a closed part adjacent one or more conductive electrodes located around its path.
  • the discharging electrodes may be earthed or have applied thereto an electric potential opposite that built up on the belt.
  • the photoconductive layer may be charged through an intermediate insulating film or layer which may be separate from the copy paper and interposed between the charging electrode and the photoconductive layer.
  • the insulating film or layer may for example be laid on the photoconductive material or may be applied to the said material by way of an additional film for example by spraying or other technique during the manufacture of the copy paper.
  • Preferred insulating materials are polypropylene, cellophane and paper.
  • a sheet of transparent material such as plastics or glass may be located in contact with the charged photoconductive surface during the exposure of the latter to light.
  • This last mentioned sheet of transparent material filters out the wavelengths of light normally absorbed by the photoconductive material employed.
  • the filtering materials may be such as to form a dichroic filter typically a red or blue or green filter.
  • the substrate may be intrinsically an electrical insulator or have applied thereto an electrically insulating layer.
  • the light for illuminating the document has to pass through the photoconductive material which is thus preferably at least translucent but thereafter only has to pass through the substrate material first to the document and thereafter from the document before it is available to form the charge pattern in the appropriately polarised surface of the photoconductive material.
  • a white on black copy is required from a black on white document and vice versa.
  • Such a copy will be referred to as a "reversed copy” and the method of the invention can be adapted to produce a so-called reversed copy if during development a charged and exposed copy paper with the invention is placed in close proximity to a conductive member which is electrically floating relative to earth potential.
  • the member may be in the form of a plate or roller and a preferred material for the same is aluminium.
  • apparatus for performing the method of the invention comprises an electrostatic charging station including a corona discharge, a high voltage source for powering same and applying a positive potential to a sheet of copy paper located in the charging station, an exposure station to which the charged copy paper can be moved, which exposure station includes a light source for illuminating the charged coated surface of the copy paper, the apparatus being adapted to expose the other side of the copy paper as it is stretched across the exposure station to allow it to be brought into contact with a document to be copied, means for developing the electrostatic charge pattern remaining on the charged surface of the copy paper after exposure at the exposure station, which development means include finely divided toner means for fixing the developed image onto the copy paper.
  • the source of high voltage may be a conventional high voltage generator using the example a transistor oscillator circuit and appropriate transformer or may comprise a piezo electric crystal with means for stressing the crystal and subjecting it to considerable forces to produce (in manner known per se) a high voltage across the faces of the crystal.
  • rectifying circuit means or switch means may be provided to ensure that pulses of only one polarity are supplied to the charging electrode.
  • rectifying circuit means this may be of the half wave or full wave type.
  • voltage multiplying circuits may be employed to increase the potential available for charging the paper.
  • the insulating film may be in the form of an endless belt of plastics material or the like with means for removing charge therefrom so as to eliminate charge build up during successive chargings.
  • the insulating sheet material may be in the form of a backing sheet lightly adhereing to the rear of the copy paper and rolled up therewith on a drum or attached to the rear of separate sheets to be fed from a hopper, and after the copy paper has passed through the apparatus, and a copy has been formed thereon, the insulating backing sheet is peeled from the copy and may be discarded. So as not to interefere with the exposing step, the insulating material must be transparent and non-light dispersing.
  • an improved paper for use in a method according to the invention comprises:-
  • Fig.l the cross section shows a copy paper having a substrate of GLASSINE type N802 paper as manufactured by Wiggins Teape Limited designated by reference numeral 10 having applied to one face thereof a thin layer of zinc oxide 12.
  • the substrate 10 is not rendered conductive nor is a conductive resin or film located between the substrate 10 and the zinc oxide layer 12.
  • Fig.2 shows an alternative arrangement in which a similar zinc oxide layer 12 is formed on a substrate 10 which again may be GLASSINE type N802 paper as previously described.
  • a transparent plastics film 14 which can be peeled off if required. The paper together with the film is passed through the charging stage and exposure stages of apparatus to be described and after passing through a toner bar for example the plastics film can be pulled away from the rear of the copy paper substrate 10.
  • toner and dispersant can cling to the rear of the copy paper after passing through the toner bath and if the rear of this paper is in fact in the form of a detachable film then any toner etc., clinging thereto can be discarded together with the film leaving the back of the copy clean.
  • Fig.3 of the drawings is a flow diagram illustrating one embodiment of apparatus for performing the method of the invention.
  • the apparatus comprises a roll of coated copy paper designated by reference numeral 16 with feed rollers 18,20 and 22. Beyond the rollers 22 is located a guillotine 24 or other knife device for cutting the paper which is passed through the line.
  • the paper is coated with zinc oxide and as previously described with reference to Fig.l the zinc oxide is supported on a substrate of GLASSINE paper of the type described.
  • the coated paper is rolled with the zinc oxide surface outer most so that when unrolled as in Fig.3., the upper surface of the paper is the coated surface.
  • the first operation is to charge the coated surface of the paper and this is achieved using a corona charging electrode typically in the form of stretched wire 26 which is electrically connected via the conductor 28 to the positive output. of high tension generator 30 to be described.
  • the other side of the generator is connected through a high resistance 32 and conductor 34 to a conductive plate typically a metal plate designated 34 and located on the underside of the paper where the latter is stretched under the charging electrode 26.
  • the conductive plate 34 is supported on two mounts 36 and 38 from a perspex bed 40. The latter serves as a mounting and also to electrically insulate the plate 34 from earth and can of course be any suitable material.
  • the high tension generator 30 may be an alternating current supply in which event a diode 42 is connected between the two output terminals to inhibit negative going pulses so as to maintain a positive only potential on electrode 26.
  • the value of the resistance 32 is adjustable as designated and is selected as appropriate to the material of the substrate etc.. Where 37 gramm, GLASSINE paper is used, the value of the resistor 32 is typically 200 Megohms.
  • the electrode 26 may include an earthed reflector plate typically parabolic in shape although this is not shown in the drawing.
  • the exposure region Beyond the charging stage in the direction of the arrow 44 is located the exposure region.
  • the charged paper passes below a lamp 46 in a reflecting housing 48 and below the stretched paper is located the document 50 which is to be copied.
  • the document 50 and the stretched copy paper designated by the reference numeral 52 are either maintained stationary or moved in synchronism with no relative movement therebetween at least over the illuminated section of the copy paper path.
  • An electrostatic image of the printing if any on the document is formed in known manner by reflection and absorbtion of light and the relatively uniform charged pattern obtained from the charging electrode 26 is replaced by a charge pattern corresponding to the printing or other markings on the document 50.
  • the charge pattern is such that charge remains in those regions of the coated surface which correspond to dark lines or dots or areas in the original document while as the charge is to a large extent dissipated in all other regions of the photoconductive layer.
  • the electrostatic image can be replaced by a visible image by a development stage in which the paper bearing the electrostatic charge pattern is passed through a bath 54 containing a liquid dispersant 56 containing in suspension finely divided toner powder.
  • a liquid dispersant 56 containing in suspension finely divided toner powder.
  • the latter is black so that black dots, lines and areas appear on the coated surface corresponding to the areas remaining charged after the exposure stage.
  • the guillotine or knife means 24 is operated so as to remove the exposed and developed length of paper bearing the final copy.
  • a film of insulating material has to be located between the rear of the paper and the conductive plate 34, this may be wound on the reel 16 with the paper in accordance with the embodiment of Fig.2 and the insulating film can be stripped from the back of the copy paper after it has been cut by the knife or guillotine 24.
  • Fig.4 shows an alternative charging region for the system shown in Fig.3.
  • the copy paper 52 does not have an insulated backing layer but nevertheless requires one between it and the conductive plate 34.
  • an endless belt of appropriate insulating plastics material 58 is stretched around two rollers 60 and 62 at least one of which is driven so as to rotate the endless belt 58.
  • the belt is rotated in the same direction and at the same speed as the paper is to move through the system.
  • any charge induced in the endless belt 58 is removed as the belt passes the discharge electrodes or electrode 64.
  • the high tension source 30 of Fig.3 may to advantage be a manually or battery operated device so as to allow the unit to be portable.
  • a manual device this may either be in the form of a highly geared generator and appropriate high tension transformer circuit or more preferably a squeeze unit incorporating a piezo electric crystal which when subjected to a squeezing force develops a high tension voltage across two faces of the crystal, As is well known, such cyrstals develope an equal and opposite voltage when the strain is released and to this end a rectifying diode such as 42 is provided to remove unwanted polarity spikes from the output.
  • a full wave rectifying bridge circuit may be employed in the alternative so as to increase the available direct current energy.
  • a preferred material for the plate 34 is aluminium.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electrophotography Using Other Than Carlson'S Method (AREA)
  • Combination Of More Than One Step In Electrophotography (AREA)
  • Photoreceptors In Electrophotography (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
EP82300091A 1981-01-10 1982-01-08 Procédé à copier électrophotographique Withdrawn EP0056313A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8100719 1981-01-10
GB8100719 1981-01-10

Publications (2)

Publication Number Publication Date
EP0056313A2 true EP0056313A2 (fr) 1982-07-21
EP0056313A3 EP0056313A3 (fr) 1982-11-03

Family

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EP82300091A Withdrawn EP0056313A3 (fr) 1981-01-10 1982-01-08 Procédé à copier électrophotographique

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EP (1) EP0056313A3 (fr)
GB (1) GB2094490A (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0124660A1 (fr) * 1983-04-28 1984-11-14 PAYNE, John, Michael Machine à copier des documents

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7542791B2 (en) 2003-01-30 2009-06-02 Medtronic Navigation, Inc. Method and apparatus for preplanning a surgical procedure

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3003404A (en) * 1956-12-21 1961-10-10 Metcalfe Kenneth Archibald Machine for effecting electrostatic printing
GB893011A (en) * 1958-02-27 1962-04-04 Ozalid Co Ltd Improvements in and relating to photographic and like reproduction methods and apparatus and materials for carrying such methods into effect
GB995491A (en) * 1961-03-16 1965-06-16 Gevaert Photo Prod Nv Photoconductive, thermoconductive and like dielectric recording materials
DE1472979A1 (de) * 1959-02-21 1969-09-18 Kalle Ag Elektrophotographisches Reflex-Kopierverfahren
US3598582A (en) * 1967-09-18 1971-08-10 Ibm Photoconductive element exhibiting photoconductive dichroism and process of using same
US3612680A (en) * 1968-11-26 1971-10-12 Equipment Dev Corp Reflex to direct photocopying method and apparatus

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3003404A (en) * 1956-12-21 1961-10-10 Metcalfe Kenneth Archibald Machine for effecting electrostatic printing
GB893011A (en) * 1958-02-27 1962-04-04 Ozalid Co Ltd Improvements in and relating to photographic and like reproduction methods and apparatus and materials for carrying such methods into effect
DE1472979A1 (de) * 1959-02-21 1969-09-18 Kalle Ag Elektrophotographisches Reflex-Kopierverfahren
GB995491A (en) * 1961-03-16 1965-06-16 Gevaert Photo Prod Nv Photoconductive, thermoconductive and like dielectric recording materials
US3598582A (en) * 1967-09-18 1971-08-10 Ibm Photoconductive element exhibiting photoconductive dichroism and process of using same
US3612680A (en) * 1968-11-26 1971-10-12 Equipment Dev Corp Reflex to direct photocopying method and apparatus

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0124660A1 (fr) * 1983-04-28 1984-11-14 PAYNE, John, Michael Machine à copier des documents

Also Published As

Publication number Publication date
EP0056313A3 (fr) 1982-11-03
GB2094490A (en) 1982-09-15

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