US3892566A - Electrostatic process where the developer is the photosensitive medium - Google Patents

Electrostatic process where the developer is the photosensitive medium Download PDF

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US3892566A
US3892566A US332396A US33239673A US3892566A US 3892566 A US3892566 A US 3892566A US 332396 A US332396 A US 332396A US 33239673 A US33239673 A US 33239673A US 3892566 A US3892566 A US 3892566A
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Prior art keywords
light
developer
image
medium
toner
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US332396A
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English (en)
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Alan J Brock
John D Brock
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Repco Research Pty Ltd
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Repco Research Pty Ltd
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G17/00—Electrographic processes using patterns other than charge patterns, e.g. an electric conductivity pattern; Processes involving a migration, e.g. photoelectrophoresis, photoelectrosolography; Processes involving a selective transfer, e.g. electrophoto-adhesive processes; Apparatus essentially involving a single such process
    • G03G17/04—Electrographic processes using patterns other than charge patterns, e.g. an electric conductivity pattern; Processes involving a migration, e.g. photoelectrophoresis, photoelectrosolography; Processes involving a selective transfer, e.g. electrophoto-adhesive processes; Apparatus essentially involving a single such process using photoelectrophoresis
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
    • Y10S430/001—Electric or magnetic imagery, e.g., xerography, electrography, magnetography, etc. Process, composition, or product
    • Y10S430/102—Electrically charging radiation-conductive surface

Definitions

  • a further disability with any of the systems is that unless the fixing conditions are correct the image can be lost or can deteriorate with time.
  • the object of the present invention is to produce a system which does not require a photoconductive surface to produce an image and does not require a field applied between a pair of electrodes through one of which the image must be projected.
  • the marking medium is itself the photoconductive medium which is energised in such a way that it deposits according to an electrical field and thus the deposition can take place on any plain surface of paper or any other suitable medium and moreover because the developer is the photosensitive medium and has the required light sensitivity, deposition takes place only on the areas required.
  • the developer being deposited imagewise by using a corona which electrically charges the developer particles but light or other electromag netic waves discharge the developer particles so that they deposit pattern wise on ordinary paper or any other suitable surface under influence of the corona field.
  • the toner particles must be capable of taking a charge from a corona field to move in such field but also to have the charge modified in the areas of the image where light exists.
  • the developer has marking particles which have photoconductive properties and as an example the marking particles could comprise zinc oxide or a similar particulate photoconductor which is coloured to give the required marking medium, or it could be zinc oxide particulate material or the like which has been coated with a resin to form a compound particle, or it can be a photosensitive dye, but whatever the form, either the photoconductive medium or the resin or other associated medium is dyed or coloured or is selected according to colour so that it can go down in a selected area to form the actual image but will not go down in those areas where the deposition conditions do not exist.
  • the marking particles could comprise zinc oxide or a similar particulate photoconductor which is coloured to give the required marking medium, or it could be zinc oxide particulate material or the like which has been coated with a resin to form a compound particle, or it can be a photosensitive dye, but whatever the form, either the photoconductive medium or the resin or other associated medium is dyed or coloured or is selected according to colour so that it can go down in a selected area to form
  • the basic principle of the invention is the use of a developer which itself has the necessary light sensitivity to activate the developer to go down imagewise.
  • the invention consists in the application of the developer to a surface on which the image is to be produced simultaneously with the projection on the surface of an image pattern or light or other electromagnetic waves so that developer present at this lo cality will vary in its charge holding properties according to the amount and colour of effective light striking the particular developer particles.
  • the photoconductive medium in particulate form can be coated with a resin which is at least slightly soluble in the developer during the time of suspension in the developer carrier liquid so that when the image is developed and the particles moved down onto the surface in accordance with the selective action of the light and the field. these particles will adhere to the surface and when the image so produced is removed from the developer, and the partial solvent for the resin evaporates, the resin will be firmly bonded to the surface and a smudge free image will result.
  • a fixing medium is not necessarily associated with the photoconductive medium, it can be applied to the image before or after development has taken place, or a fixing medium which can be in solution in a carrier liquid can be applied overall irrespective of image selectivity by simply going down onto the surface on which the marking particles have been deposited, in which case what is equivalent to a glazed surface can be produced which however is still free of photosensitive media excepting in the actual image areas and therefore does not have the weight and other problems which result where a complete surface is given a coating of photoconductor or the like onto which the marking medium is then deposited.
  • dyed photoconductive particles such as zinc oxide can be suspended in a liquid such as a hydrocarbon having an electrical resistivity in excess ohm. cm. and a dielectric constant of for instance 3 and these developer particles can then be moved in the liquid to deposit on the surface where they are required in a differential manner according to the applied field and light modifying effect of the image.
  • the carrier liquid can be more conductive. say having a resistivity in excess of 10 ohm centimetre.
  • the invention can also be applied in dry developer processes provided the developer medium is suspended or moved in a medium such as a gas which can have the required characteristics to permit the light activated particles to discharge to attain the differential movement of charged and discharged particles.
  • FIG. I shows somewhat schematically in side eievation a system in which a stack of sheets of paper are fed forward through a coating applicator station. the developer which is coated on at this station being then moditied by the projection thereon of an image and the application of a corona discharge, after which the excess developer is removed where not attached the sheet being then dried and the paper discharged to a receiving tray.
  • FIG. 2 shows a similar type of application but utilising a rotary drum feed, but again involving a stack of papers which are fed through a developer applicator stage and then imaged by the corona and light. after which the excess developer which is not forming the image is removed from the sheet and the sheet is dried and fed to a receiving tray.
  • FIG. 3 is shown diagrammatically the general basis of the invention where (a) shows how the developer is applied to the paper and charged by a corona producing device and light modified at the same time, while (b) shows how the wash then removes the unattached developer material to leave only the image on the paper,
  • a stack of papers 1 is carried on a platform 2 which is adapted to be fed upwardly by a lifting mechanism 3, such as a hydraulic mechanism.
  • the stack of papers 1 is guided by the frame 4.
  • a vacuum platten 5 which is connected through a line 6 to a suitable vacuum source. This is regulated so that when the vacuum platten 5 which moves on the guide 7 is energised. the perforate surface 8 of the vacuum platten engages the upper sheet of paper from the stack 1 and the platten is then moved in the direction of the arrow to cause the paper to traverse the developer applicator zone 9 which comprises a pair of rollers 10 oppositely driven to feed developer to the area 9 from a tank 11 containing the developer.
  • Developer 12 is fed to the tank 11 through a line 13 and surplus developer is drawn off through the line [4.
  • the developer comprising a particulate photoconductive or photoinsulative substance in an insulating medium.
  • the photoconductive substance being tinted such as by including or having on it a resin coating which is adapted to hold a charge on its surface in that it is an insulator, but is slightly soluble in the carrier liq uid so that the surface of the particles is in a condition where when the surface to which it has been applied is thoroughly dried, the tackiness of the medium will cause permanent adhering to the surface.
  • the vacuum platten 5 passes on until it is at the imaging station 16, where an image is projected on to the paper by a projector 17 having a lens 18 and a transparency or the like 19, this then producing a light image on the photosensitive medium on the paper.
  • a pair of corona wires 20 are alternately actuated from a commutator 2] at a high frequency so that each wire is energised a number oftimes during the continuance of the illumination.
  • the high voltage supply unit being designated 22.
  • the vacuum platten 5 is now moved on to pass the paper over the washing station 25 which comprises a tank 26 having a supply of washing fluid.
  • washing fluid which may be similar to the carrier liquid, applied to it through the line 27 and removed through the line 28 so that there is a renewal of this liquid, or the liquid may be passed through filter or the like (not shown) by means of a pump, (also not shown) to maintain the required purity of the liquid.
  • This liquid may be chosen to soften the developer particles for fixing purposes when the liquid is removed.
  • a pair of rollers 29 which are driven in opposite directions by a motor or the like so that they carry liquid upwards on their outer peripheries to form a pool 31 of agitated liquid which is pro jected into the path of the paper being carried across this washing locality by the vacuum platten S. and the action of this is to remove any of the coating particles which are not rigidly held so that only the particles which were forced into firm contact by the field will re main in position on the surface of the paper sheet but the remaining developer particles will be removed and the final product will then be a plain sheet of paper similar to that which was fed into the machine from the paper stack excepting that an image is now produced on it by the adhesion at this stage of the coloured coating particles.
  • any carrier liquid remaining, and washing fluid. is evaporated, thus causing the image to be firmly fixed to the paper surface due to the resin which is present and which hardens as the liquid is evaporated.
  • the platten 5 then moves on to the discharge locality 35 where the vacuum is terminated and if necessary a slight positive pressure applied to eject the sheet on to the tray 36.
  • the platten 5 then returns to its starting locality, and when a further copy is to be made. the vacuum is again applied and after engaging a paper the platten moves forwardly through the various stations to produce another copy.
  • a paper stack 40 is guided by a frame 41 and rests on a lifting platform 42, which is urged upwardly by a hydraulic mechanism 43 or any other suitable loading such spring loading.
  • a drum 44 which has a plain periphery excepting at a paper picl-e up location where it has a perforate portion 45 behind which is a cavity defined by a wall 46 to form a vacuum platten 47.
  • a perforate portion 45 draws paper towards it and holds the sheet firmly on the perforate portion so long as the suction is applied, this being defined approximately by the line after which the suction in the platten is released and a positive pressure 1) applied over the are indicated in the illustration. the points marked corresponding in each case to the leading edge of the platten 47.
  • the action of the platten 47 is to draw the top sheet of the paper from the stack against the perforate portion and hold it there so that as the drum rotates in the direction of the arrow. a sheet of paper will be drawn out from stack 40 and will be firmly held on the platten 47 by the suction applied thereby.
  • Adjacent the paper stack 40 is the coating station 50 which comprises a tank 51 having within it a roller 52 driven by a belt 53 from the gear box 54 ofa motor 55, the tank 51 containing in it the developer 56.
  • the roller 52 is constantly driven in the direction of the arrow and that serves to keep coating medium agitated and also to keep the surface of the coating roller 52 wet with the coating liquid.
  • an applicator roller 57 which has its surface wetted with the developer liquid 56, but the applicator roller 57 is under control of the solenoid 58 so that it can be pushed forwardly at an appropriate time to contact a sheet of paper from the stack 40 as it reaches this locality and thus apply coating material in the form of the developer to the surface of the paper.
  • the light image is in this case produced from an original placed on to the curved transparent rest 60, and is scanned by a mirror 61, which moves at a rate such that scanning of the original takes place in proportion to the rotational speed of the drum 44, a lens 62 projecting the image from the mirror through a slit 63 on to the paper as it passes through this station.
  • the corona wires are indicated by 65 and are connected through the commutator 66 to the high voltage generator 67, the wires 65 being again alternately fed at a rapid rate for the purpose of obtaining a scanning sweep over the slit 63 as it will be realized that if both wires were fed simultaneously, the two Coronas produced would deflect to give a null zone on a medial level but by alternating the supply to the wires each in turn cover the slit 63 so that the result is a balanced charging action through the slit to the drum 44, the material forming the slit being insulating if necessary.
  • the surface of the paper has a developer image produced on it as it passes the slit 63, but imme diately it leaves this area it reaches the washing station 70 which comprises a wall 71 which may be an electrode.
  • this wall being provided with three ducts 72, 73. and 74, the duct 72 being a central duct, and like the ducts 73 and 74 extends across the complete width of the drum the central duct 72 being a supply duct for the washing fluid, while the ducts 73 and 74 on either side of it are suction ducts which remove the fluid.
  • the paper From the washing locality the paper enters a drying station 76 and after leaving this is discharged from the platten by termination of the suction and by the application of positive pressure if required, to be received on the tray 77.
  • the drum can continue to rotate until a required number of copies has been produced because each time it reaches a position shown in FIGv 2 and the suction is applied, a sheet of paper will be picked up by the platten and will be moved first through the coating station then through the exposure station and then through the washing and drying stations to produce the final copy.
  • FIG. 3 is shown somewhat schematically how the process operates.
  • At (a) is shown how the sheet 80 is placed on to a base 81 which is earthed and forms a base electrode.
  • 82 represents a pair of corona discharge wires and these are connected to the high voltage generator 83 through a commutator 84.
  • the high voltage generator is also earthed.
  • Excitation of the generator 83 causes a corona to be produced between the discharge wires 82 and the base electrode 8].
  • a flow of developer which forms the coating material into the light image and corona zone this comprising photosensitive particles 86 held in a carrier liquid 87, this preferably being a liquid having an insulating value above l0 ohm centimeter photoconductor particles preferably being coating with a colouring medium corresponding to the colour of the final reproduction required, which colouring medium can be a resin slightly soluble in the carrier liquid, but more preferably in the washing fluid, so that when subsequently the liquid is dried off, any particles adhering to the sheet 80 will be bonded thereto.
  • the projector 90 produces the white zones 9] representing a light image.
  • the shaded zone 92 indicating dark areas.
  • photoconductor and photo-insulators may be used. the only requirement being that there shall be a difference in conductivity of those particles which are in the light part of an image and those which are in the dark part thereof. which positioning affects their conductivity and. thus. their mobility and retention on the surface which forms one of the electrodes and which supports the medium on which the image is to be produced.
  • the marking particles which. as said. must be light sensitive so that their conductivity changes when light is projected on to them and this. of course. means that if a selection is made of particles which are sensitive to one particular colour of light then those particles only will be activated when that light strikes them and. therefore. if three groups of marking particles are used each sensitive to one of the colours of a colour system. the correct particles can he made to go down in correct localities in accordance with a colour image which is projected on to the surface.
  • Zinc oxide Special Z. product of Durham Chemicals Aust. 5 grams lsopar G. isoparaftinic solvent of Esso Corp 200 grams By kneading these materials in a ball mill for about 3 hours a white toner suspension was produced which was fed into the exposure unit. During exposure and in the presence of an electric field the white zinc oxide particles migrated to the dark areas of the image producing a negative reproduction.
  • EXAMPLE 2 The photosensitive response of the above suspension in Example 1 was modified by introducing a polarity regulating agent such as Beckosol 1535 a product of Reichold Corp. of Japan.
  • a polarity regulating agent such as Beckosol 1535 a product of Reichold Corp. of Japan.
  • Example 3 The suspension of Example I was modified by introducing a soluble fixative into the Isopar G such as a hydrocarbon resin or a rubbery polymer such as Solprene 1206, a product of the Phillips Imperial Chemical Ltd.
  • a soluble fixative such as a hydrocarbon resin or a rubbery polymer such as Solprene 1206, a product of the Phillips Imperial Chemical Ltd.
  • EXAMPLE 4 The photoresponse of the zinc oxide in Example l. was modified by dyeing the zinc oxide with quinoline yellow. rose bengal. or bromophenol blue from 0.5 per cent methyl cellusolve solutions.
  • EXAMPLE 5 The zinc oxide was dyed with acridine yellow. methylene blue. bromophenol blue or naphthol green from l per cent methanol solution.
  • EXAMPLE 7 In Example 6. the Watchung Red was replaced with Benzidine Yellow GGR a product of the Toyo Ink. Co. oflapan or Phthalocyanine green LX or copper phthalocyanine Cl 74260 from Imperial Colour and Chemical Co. of USA or Irgalite GLSM phthalocyanine blue of Geigy Co. Switzerland.
  • Example 8 In Example I the zinc oxide was replaced by cadmium selenide, X4401. product of Dry Colour and Chemical Manufacturing Co. Victoria, Australia.
  • Example 9 In Example I the zinc oxide was replaced by cad mium sulphide, copper activated.
  • EXAMPLE 10 In Examples 1 and 6 the photosensitive medium was replaced by Naphthol Red B. or Calcium Lithol Red. or lndofast double scarlet toner. or Quindo Magenta, or Vulcan Fast Red BBE toner or the like.
  • Cadmium Reds Pigment Red I08 Cl WW6 (Cadmium sulphs selenidcs) eg. Cadmium Red c ⁇ . I.C.I.A.N 7.v Red Oxide Pigment Red l0lillll (.l. 7749] (Ferric Oxide) cg. Natural Spanish Red ()xide ex Hardic Trading BLLES ORGANIC hthtiloeyanine Pigment Bliic I5 ('I 'NIhll Blue teopperl e g. NIURLISIILII Fast Blue BGA ex l.(' IAN Z.
  • Monoazo Blue Pigment Blue 23 CI cg Hclio Fast Brilliant Blue RR ex Bayer Lmerkusen lndanthroiie Blue Pigment Blue C l Nmtlll cg Monolite Fast Blue SR5 ex LC l A.l ⁇ '.7..
  • INORGANIC Ultramarine Blue Pigment Blue 29 CI. 77011? Polysulphidc of Sodium (a K Li or Agi apatino silicate) cg. L'ltraniarine Blue ex l.(.l..- ⁇ N].
  • Iron Blues Pigment Blue 27 (.l. T'ISIU 77521) t Potassium (or sodium or ammonium l l'crric l errocyaiiidcl eg Prussian Blue ex Rohi. Bryce,
  • YELLOWS ORGANIC Arylamide Yellow Pigment Yellow 1 Cl. l 1680 (2I'lIIlOp't0IUILII11C aectoacettimlide) e.g. Monolite Fast Yellow GNA ex I.C.I.A.N.Z.
  • Benzidine Yellow Pigment Yellow 12 (II. 21090 Anilide (3.3 dichloro henzidine acetoacetanilide) eg. Graphtol Yellow A-HG ex SLIIRIUL Mono Azo Yellow Pigment Yellow 97 Cl cg. Permanent Yellow FGL ex Austv Hoechst Benzidine Yellow Pigment Yellow l4 C I.
  • the method ol producing images on a surface which comprises:
  • which developer comprises a carrier liquid with an electrical resistivity in excess of ohm centimeter and a toner medium which can receive a charge from a corona but which charge is modified by light when and where the said toner medium is subjected to light whereby the electrical resistivity of the said toner medium varies in light and dark areas and thus varies in retention delay characteristics on the said surface when in a field.
  • a method of producing images which comprise the steps of:
  • first being a developer application station where the surface is wetted with developer.
  • second station being the corona charging station for the developer and the simultaneous light exposure through a slit associated with a traversing scanner whereby the image is progressively formed on the said surface as it passes the said slit.
  • the third station being a washing and drying station through which the said surface passes.
  • the method of claim 1 wherein the said surface travels continuously through a series of stations.
  • the first being a developer application station where the surface is wetted with developer by a roller which carries the developer to the said surface.
  • the second station being the corona charging station for the developer and the simultaneous light exposure through a slit associated with a traversing scanner whereby the image is progressively formed on the said surface as it passes the said slit.
  • the third station being a washing station through which the said surface passes. said washing station comprising ducts to cause liquid flow over the surface to be washed by supplying liquid to the said surface and withdrawing the liquid by suction at a locality remote from the supply locality.
  • toner particles consist of light sensitive particles the conductivity of which changes in the simultaneous presence of light and a corona discharge. said toner particles being disposed in a carrier liquid having an electrical resistivity in excess of l0 ohm. centimeter.
  • the light sensitive developer medium is a particulate photoconductor or photoinsulator suspended in a hydrocarbon solvent with an electrical resistivity in excess of 10 ohm centimeter. the photoconductor being milled in the said solvent to produce a fine wetted suspension of the photoconductor in the said solvent.
  • the said developer medium contains a hydrocarbon resin or a rubbery polymer polarity regulating and fixing agent which adheres to the said photoconductor or photoinsulator and is wetted by the said solvent.
  • particulate photoconductor has its photoresponse modified by dyeing the photoconductor to increase its sensitivity to light of a selected wavelength.
  • the particulate photoconductor is zinc oxide having its photoresponse modified by dyeing the zinc oxide with dyes selected from the following grouping: quinoline yellow. rose benzal. bromophenol blue. from a methyl celusolve so lution or acridine yellow. methylene blue. bromophenol blue or naphthol green from a methanol solution.
  • the light sensitive developer medium is a coloured substance dispersed in a carrier liquid with an electrical sensitivity in excess of 10 ohm centimeter, the said coloured medium being taken from the following grouping:
  • Phtholocyanine blue Benzidine yellow. Para red.

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US332396A 1972-02-18 1973-02-14 Electrostatic process where the developer is the photosensitive medium Expired - Lifetime US3892566A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2502355A1 (fr) * 1981-03-20 1982-09-24 Philips Nv Dispositif de nettoyage pour le support d'image intermediaire d'un dispositif d'impression electrophoretique
FR2502803A1 (fr) * 1981-03-26 1982-10-01 Philips Nv Buse servant a appliquer du liquide sur le support d'image intermediaire d'un dispositif d'impression electrophoretique

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3234019A (en) * 1961-04-10 1966-02-08 Xerox Corp Method for formation of an electrostatic image resistant to deterioration on storage

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3234019A (en) * 1961-04-10 1966-02-08 Xerox Corp Method for formation of an electrostatic image resistant to deterioration on storage

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2502355A1 (fr) * 1981-03-20 1982-09-24 Philips Nv Dispositif de nettoyage pour le support d'image intermediaire d'un dispositif d'impression electrophoretique
FR2502803A1 (fr) * 1981-03-26 1982-10-01 Philips Nv Buse servant a appliquer du liquide sur le support d'image intermediaire d'un dispositif d'impression electrophoretique

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AU5225073A (en) 1974-08-22
JPS4890742A (en(2012)) 1973-11-27
GB1422716A (en) 1976-01-28

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