US3527684A - Method of increasing contrast in electrophoretic reproduction - Google Patents

Method of increasing contrast in electrophoretic reproduction Download PDF

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Publication number
US3527684A
US3527684A US622499A US3527684DA US3527684A US 3527684 A US3527684 A US 3527684A US 622499 A US622499 A US 622499A US 3527684D A US3527684D A US 3527684DA US 3527684 A US3527684 A US 3527684A
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Prior art keywords
photoconductor
particles
reproduction
layer
developer
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Expired - Lifetime
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US622499A
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English (en)
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William C York
James G Jarvis
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Eastman Kodak Co
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Eastman Kodak Co
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G13/00—Electrographic processes using a charge pattern
    • G03G13/22—Processes involving a combination of more than one step according to groups G03G13/02 - G03G13/20
    • 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
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/02—Charge-receiving layers
    • G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
    • G03G5/06—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being organic
    • G03G5/0601—Acyclic or carbocyclic compounds
    • G03G5/0612—Acyclic or carbocyclic compounds containing nitrogen
    • G03G5/0614—Amines
    • G03G5/06142—Amines arylamine
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/10—Bases for charge-receiving or other layers
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/12—Developers with toner particles in liquid developer mixtures

Definitions

  • ABSTRACT OF THE DISCLOSURE A method for increasing the contrast between the exposed and unexposed areas of a pattern of conductivity induced in a photoconductive layer, in which said layer is treated prior to exposure so that charged particles will be repelled from the unexposed areas upon development of said pattern.
  • This invention relates to electrophotographic reproduction and more particularly to an improved electrophoretic process by which contrast between the exposed and unexposed areas of a photoconductive material is increased upon developing the imagewise pattern by deposition of charged particles.
  • Desirably useful organic photoconductors such as those based on triphenylamine, would be ineffective in such an aqueous developer system, because the resistance of the photoconductor per unit of area would be much too high to permit obtaining the required current flow with practical voltages. Further, there is deposition of charged particles on the unexposed areas of the photoconductive material for at least some part of the time of current flow which serves to decrease the contrast between the image and background areas.
  • the invention relates to a system comprising a photoconductive material contiguously associated with an electrically conductive support which constitute a composite record sheet.
  • An electrically insulating organic liquid vehicle is used for the development bath and contains dispersed charged toner particles.
  • the record sheet is positioned in the bath and in spaced relation to a development electrode, a power supply including a switch being connected between the support and the electrode.
  • the photoconductive material can be precharged to enhance contrast; (2) a high impedance photoconductor, such as amorphous selenium or any one of many other organic photoconductive compounds, which leads to lower current density, hence, a smaller power supply, can be used; and (3) a negative-positive or a positive-positive can be made.
  • the invention involves exposing "ice a pattern of radiation on the surface of a photoconductive layer applied to an electrically conductive support or sheet.
  • This structure comprises a record sheet which is immersed in a developer bath with the photoconductive layer substantially parallel to, spaced from and facing a development electrode in the bath. Both the record sheet and the electrode are electrically connected in series with one another through a power supply, Le, a source of electrical potential including a switch, one side of the source being connected to the support and the other side connected to the electrode.
  • a power supply, Le a source of electrical potential including a switch, one side of the source being connected to the support and the other side connected to the electrode.
  • either one of the support or the electrode can be transparent so as to enable the pattern of radiation to be incident on the photoconductive layer.
  • the pattern of radiation is projected through the bath and through the transparent conductive support to the photoconductive layer.
  • the developer-treatment bath comprises a dispersion of electrically charged toner or developer particles in an electrically insulating organic liquid which is inert to the charged particles and the electrodes and stable against any change in an electrical field.
  • One object of the invention is to provide an improved electrophotographic reproduction system for obtaining an imagewise reproduction of improved contrast.
  • Another object of the present invention is to provide an improved electrophotographic reproduction system in which a photoconductive material is treated either prior or subsequent to exposure for obtaining increased contrast between the exposed and unexposed areas of the imagewise reproduction.
  • a further object of the invention is to provide an improved electrophotographic reproduction system in which lower current densities, and hence a smaller power supply are required to obtain a reproduction having increased contrast.
  • Yet another object of the invention is to provide an improved electrophotographic reproduction system in which an electrically insulating organic (nonaqueous) liquid having a dispersion of charged particles is used as a developer of the electrostatic image.
  • Still another object of the invention is to provide an improved electrophotographic reproduction system in which exposure and development of a photoconductive record sheet can be carried out simultaneously and either a negative-positive or a positive-positive reproduction can be obtained in accordance with the color of the charged particles that are dispersed in the developer liquid.
  • FIG. 1 is a schematic vertical cross-sectional view of one embodiment of the invention in which the record sheet is the anode and the development electrode (i.e., the cathode) is transparent;
  • FIG. 2 is a schematic view similar to that of FIG. 1 1n which the record sheet comprises a transparent conductive support which serves as the cathode;
  • FIG. 3 is a schematic vertical cross-sectional view of another embodiment of the invention in which an imagewise reproduction is obtained by the use of a reusable photoconductive belt.
  • a cassette 10 or similar container holds the developer 11 comprising an electrically insulating organic liquid 12 wherein there are dispersed negatively charged toner or developer particles 13 (FIG. 1) or positively charged particles 14 (FIG. 2).
  • the record sheet 15 (FIG. 1), comprising an electrically conductive support 21 and a layer of photoconductive material 22, is supported on and insulated from the bottom of cassette 10, the support 21 being connected by a suitably arranged conductor through a switch 17 to a source of potential 18.
  • the source of potential 18 is such as to be capable of producing an electrical field of about a few thousand volts per centimeter between record sheet 15 and a development electrode 19 which can have a central opening or can be transparent, such as a NESA glass electrode (a product of Pittsburgh Plate Glass Co.) composed of a glass sheet having an electrically conductive coating containing stannous oxide on one surface.
  • the source of potential 18 is also connected through a conductor to electrode 19 which is supported by suitable insulator brackets 20 from the top rim of cassette and thus insulated from it.
  • the record sheet is supported on brackets with the layer of photoconductive material 22 facing electrode 19 which is supported on and insulated from the bottom of cassette 10.
  • support 21 is transparent as well as conductive and can be of cellulose acetate or a similar material that has coated thereon or incorporated therein a material which will provide the necessary electrically conductive characteristics.
  • a light source 24 emits light which by means of a suitable lens system 25 is directed through an image-bearing transparency 26.
  • the image radiation pattern is projected by lens 25 through the electrode 19 (FIG. 1) or through the transparent support 21 (FIG. 2) onto the layer 22, thereby exposing the photoconductive layer 22 to a corresponding pattern of radiation.
  • switch 17 is closed.
  • the charged toner particles 13 negative in FIG. 1, and 14 positive in FIG. 2 collect on the exposed (illuminated) areas of the photoconductor 22 due to the electrical field generated between the conductive support 21 and the electrode 19. This is especially so when the photoconductor is a very good insulator in the dark.
  • any accumulation of charged particles in the unexposed (dark) areas assumes a high enough potential to cause discontinuance of particle flow to these areas.
  • such an accumulation of particles in the unexposed areas reduces the contrast between the exposed and unexposed areas.
  • the conductivity of the exposed areas of the photoconductor prevents development of any such potential. Accordingly, toner particles continue to accumulate on the exposed areas so long as the circuit is closed, a supply of charged particles is maintained in the developer, and/or photoconductivity persists.
  • the loss of contrast in the imagewise reproduction due to accumulation of toner particles on the unexposed (background) areas can be prevented by altering or biasing the photoconductive layer with the use of invisible charge carriers having a color that contrasts with that of the charged toner particles used for forming the imagewise reproduction.
  • reproductions having satisfactory contrast can be obtained even with photoconductors which may not be very good insulators.
  • an invisible charge carrier is a gaseous ion such as is produced by a corona charger.
  • the photoconductor is charged uniformly by a corona discharge, for example, as schematically shown in FIG. 3 (precharger 32), before it is placed in contact with developer 11.
  • a corona discharge for example, as schematically shown in FIG. 3 (precharger 32)
  • exposure thereof to the pattern of radiation renders the exposed areas conductive and in the unexposed areas the potential is sufficiently high and of a polarity so as to repel any charged particles.
  • the charged particles 13 in FIG. 1 and 14 in FIG. 2 accumulate only in those areas which are exposed to the pattern of radiation.
  • Another way of accomplishing the same result is to subject the photoconductor to a developer having charged particles of low color, such as colorless or white. After a suflicient number of such particles have accumulated in the unexposed areas so the potential in these areas is sufficient to repel the particles, the record sheet is brought into contact with a second developer containing charged particles of high color, such as black or a similar distinctly contrasting color, or charged particles of such contrasting color are added to the bath and the development of the imagewise reproduction then continues as already described.
  • a developer having charged particles of low color such as colorless or white.
  • a positive-to-positive reproduction procedure can be obtained by interchanging the order of using the two contrasting colored toner particles as described above.
  • a positive-to-positive reproduction can also be obtained by using a dark photoconductor on which the developer will deposit low color particles, e.g. white charged toner particles.
  • the charged particles can be selected for many reasons other than their absorption of light; for example, wettability, reactivity, luminescence, extent of solubility, or ferromagnetism.
  • EXAMPLE 1 A sheet of aluminum foil and paper laminate coated (on its foil side) with triphenylamine organic photoconductor was placed in a metal cassette and spaced oneeighth inch from a NESA glass electrode. The cell then was filled with an organic liquid developer comprising a dispersion of positively charged toner particles in an odorless paint thinner which is a deodorized highly paraffinic mineral spirits containing minimal amounts of naphthenic and aromatic hydrocarbon materials and having a boiling range of from about 352 to 386 F.
  • an organic liquid developer comprising a dispersion of positively charged toner particles in an odorless paint thinner which is a deodorized highly paraffinic mineral spirits containing minimal amounts of naphthenic and aromatic hydrocarbon materials and having a boiling range of from about 352 to 386 F.
  • the record sheet support and the electrode were then connected to a power supply and switch, as shown schematically in FIG. 1, and a potential of 300 volts (a field of 945 volts per centimeter) was applied across the NESA glass (positive) and the aluminum foil (negative) support for the photoconductor while the photoconductive layer simultaneously was given an imagewise exposure.
  • This exposure was to the image of a silver negative projected through the dispersion of the toner particles in the paint thinner.
  • the illumination was 225 foot candles without the negative in the projector.
  • a 20 second exposure/processing step yielded a reproduction bearing a visible image of high print density but with a relatively undesirable background.
  • the triphenylamine organic photoconductive coating on the laminate comprised 3 parts of triphenylamine and 7 parts of Vitel' 101X polyester resin (product of Goodyear Tire and Rubber Co.). This coating contained small amounts of crystal violet and 7,12-dioxo-l3-oxadibenzo- (u,h) fiuorene as sensitizers and maleic acid as a stabilizer.
  • the positively charged toner used in the liquid developer was prepared from 0.3 part of spirit-soluble Nigrosine (product of General Aniline & Film Corp.), 3 parts of Styron PS-Z polystyrene (product of Dow Chemical Co.), and 0.5 part of Rexobase PW cationic surfactant (product of Emkay Chemical Co.) fused together, cooled and coarsely ground. Further reduction in size was obtained by ball milling in an odorless paint thinner and then diluting this mixture with additional paint thinner to a dispersion suitable for use.
  • spirit-soluble Nigrosine product of General Aniline & Film Corp.
  • Styron PS-Z polystyrene product of Dow Chemical Co.
  • Rexobase PW cationic surfactant product of Emkay Chemical Co.
  • EXAMPLE 2 (Use of lower printing voltage) Substantially complete elimination of background deposit and enhanced sharpness of the imagewise reproduction resulted from reducing the inter-electrode spacing so that lower processing voltages can be used, thereby requiring fewer charged particles to alter the potential in the unexposed areas.
  • the precharged, imagewise exposed laminate then was developed with an impressed voltage of 5 6 volts, yielding a much sharper image produced with negligible background deposit.
  • Precharging enables using higher processing potentials for producing images without background deposits as shown by the following example.
  • EXAMPLE 3 This example employed an organic photoconductorcoated sheet similar to that of Examplel in its use of triphenylamine, but differing by being a two-layer triphenylamine composition, with one sensitized layer and one nonsensitized layer.
  • This so-called double layer triphenylamine photoconductor was prepared by gelatin-subbing a cellulose acetate support to give it improved adhesion. This was followed by applying an electrically conductive layer of an internal lactone of a copolymer of maleic anhydride and vinyl alcohol which had been made conductive by treatment with sodium hydroxide.
  • asensitized layer comprising one part of triphenylamine in 3 parts of Vitel 101X polyester resin, including 2% of a thiapyrylium salt 2,6-bis(p-ethylphenyl)-4-(para-pentyloxyphenyl)thiapyrylium perchlorate, as the sensitizer.
  • the second triphenylamine layer was applied which was the same as the first layer but-prepared without a sensitizer.
  • a two-layer triphenylamine photoconductor as described above was given a positive precharge of 400 volts with a corona wire charger to enable the photoconductor to repel toner from the background areas during develop ment.
  • the photoconductor was then treated in the same way as was the laminate of Example 1, except that the applied potential was raised to 700 volts.
  • the resulting image was of high density and without undesirable background. The precharging enables using higher processing potentials without provoking undesirable background deposits.
  • EXAMPLE 4 A two-layer triphenylamine coating, as the photoconductor on a transparent conducting cellulose acetate support (such as used in Example 3), was given a +300 volt corona precharge and placed in the electrophoretic cell (similar to that shown in FIG. 1, but modified as in FIG. 2) with the photoconductive surface spaced oneeighth inch from a blackened metal electrode. The photoconductor then was imagewise exposed through its transparent (cellulose acetate) conducting support while a potential difference of 700 volts was applied between the support and the electrode. The imagewise reproduction was markedly sharper than in prior examples, due to the fact that the pattern of radiation did not have as long a path through the liquid dispersion (see FIG. 2) before reaching the photoconductive layer as in FIG. 1 and, hence, was not as scattered.
  • EXAMPLE 5 Poor insulator used without and with corona charge
  • a zinc oxide-coated paper was prepared by coating 9. paper support with a suspension of four parts of finely divided zinc oxide in one part of a 50-50 n-butyl-isobutyl methyl methylmethacrylate copolymer (a product of E. I. du Pont de Nemours & Co.) without any sensitizer or other additive.
  • the zinc oxide-coated paper was treated as in Example 1. Since a zinc oxide layer is a relatively poor insulator, unless it has been corona charged, the result was a uniform deposit of the toner particles from the liquid developer over the entire liquid contacted zinc oxide photoconductive layer.
  • corona precharge The advantage of applying a corona precharge was demonstrated by giving another sheet of the same zinc oxide-coated paper a negative corona precharge of approximately 300 volts to enable the zinc oxide-coated photoconductor to repel toner from the background areas during development. The cell then was filled with a liquid dispersion of negatively charged toner particles. This dispersion was prepared as follows.
  • the negatively-charged zinc oxide-coated paper photoconductor then was processed in this dispersion of negatively-charged toner particles in the same way as was the photoconductor in Example 3.
  • the resulting image was of relatively high print density and without undesirable background, similar to the results in Example 3, but of lower maximum density because this negative toner was somewhat inferior to the Nigrosine and polystyrene positive toner used in Example 3.
  • Nigrosine black with polystyrene toner particles dispersed in the odorless paint thinner liquid vehicle of the developer dispersion of Example 3 were replaced by corresponding particles of a copper-activated zinc sulfide phosphor (a luminous paint pigment, product of Luminous Products, Inc.) in an amount of 0.5 gram per milliliters of the thinner.
  • a sheet of the same triphenylamine organic photoconductor of Example 3 was then treated in contact with the copper-activated zinc sulfide phosphor containing developer in the same way as in that example.
  • the resulting print manifested high print density, lacked undesirable background, and luminesced in an imagewise pattern when excited with UV radiation.
  • the photoconductor and/or the charged toner particles can be replaced, respectively, by any other compatible photoconductor or toner particles.
  • any such substitution of the photoconductor if the substitute is not a very good insulator in the dark so that the contrast of the reproduction may not be satisfactory, any of the above-described preliminary steps for providing a limited potential, usch as a corona precharge, or preliminarily contacting the photoconductor with charged developer particles having a color, such as white or colorless, can be used to provide the desired contrast.
  • a compatible dark colored photoconductor can be used together with sufficiently light colored to white or colorless charged toner particles in the developer.
  • the NESA glass transparent electrode of Example 1 can be replaced by any other similarly suitable transparent electrode.
  • the photoconductor withdrawn by unrolling from a photoconductor supply roll 31 receives a precharge as it is moved over and past a corona precharger 32.
  • the precharged photoconductor is then moved under the transparency 33 and is illuminated by the light from a light source 34 which passes through a variable slit in a mask 35 and, in turn, through transparency 33 to expose the photoconductor.
  • the black electrode 36 immersed in the developer bath in the cassette motivates'charged toner particles to migrate to the photoconductor in contact with the top of he developer bath upon completing the circuit by closing the switch in the connecting line between power supply 37 and roller contacts engaging the conductive support for the photoconductor.
  • a transfer paper web fed from a supply roll 38 is brought into contact with the photoconductor transfer rollers 39.
  • the transfer paper with the image reproduction imprinted thereon is then separated from the photoconductor.
  • the photoconductor then passes over a cleaning roller 40 and is taken up for rerun on takeup roll 41.
  • the light source 34 and mask 35 can be replaced by an optical system similar to that shown in FIG. 1 with the photoconductor arranged in the focal plane of the optical system.
  • a method for producing on a record sheet comprising an electrically conductive support and at least one layer of a photoconductive material on one surface of said support a visible imagewise reproduction of a pattern of radiation having ahigh degree of contrast, the steps which comprise:

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  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
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US622499A 1967-03-13 1967-03-13 Method of increasing contrast in electrophoretic reproduction Expired - Lifetime US3527684A (en)

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US (1) US3527684A (fr)
BE (1) BE712127A (fr)
DE (1) DE1622954A1 (fr)
FR (1) FR1561533A (fr)
GB (1) GB1221347A (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2154313A1 (de) * 1971-11-02 1973-05-10 Kalle Ag Verfahren zur herstellung von aufzeichnungen und hierzu geeignetes aufzeichnungsmaterial
US3804660A (en) * 1970-08-17 1974-04-16 Commw Of Australia Dielectric recording on insulator surfaces
US3808026A (en) * 1972-03-13 1974-04-30 Xerox Corp Liquid development of electrostatic latent image
US3836381A (en) * 1972-10-02 1974-09-17 Secretary Supply Australia Method of developing a dielectric pattern on a semiconductor surface using a two-component developer
US3839071A (en) * 1969-12-29 1974-10-01 Honeywell Inc Printing method
US4496432A (en) * 1983-06-27 1985-01-29 At&T Technologies, Inc. Electrolytic methods for enhancing contrast between metallic surfaces
US6194108B1 (en) * 1996-10-17 2001-02-27 Fuji Xerox Co., Ltd. Image forming method and image forming device using same
US20050174549A1 (en) * 2004-02-09 2005-08-11 Asml Netherlands B.V. Lithographic apparatus and device manufacturing method

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB873080A (en) * 1957-04-05 1961-07-19 Commw Of Australia Improved method of producing images by wet xerographic processes
US3038799A (en) * 1958-01-13 1962-06-12 Commw Of Australia Method of reversing the image in xerography
US3140945A (en) * 1959-06-19 1964-07-14 Commw Of Australia Electrostatic printing
US3346475A (en) * 1963-02-25 1967-10-10 Australia Res Lab Electrophotographic method using an unsymmetrical ac current during development
US3448030A (en) * 1965-06-28 1969-06-03 Xerox Corp Electrically photosensitive particles useful in photoelectrophoretic and xerographic imaging processes

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB873080A (en) * 1957-04-05 1961-07-19 Commw Of Australia Improved method of producing images by wet xerographic processes
US3038799A (en) * 1958-01-13 1962-06-12 Commw Of Australia Method of reversing the image in xerography
US3140945A (en) * 1959-06-19 1964-07-14 Commw Of Australia Electrostatic printing
US3346475A (en) * 1963-02-25 1967-10-10 Australia Res Lab Electrophotographic method using an unsymmetrical ac current during development
US3448030A (en) * 1965-06-28 1969-06-03 Xerox Corp Electrically photosensitive particles useful in photoelectrophoretic and xerographic imaging processes

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3839071A (en) * 1969-12-29 1974-10-01 Honeywell Inc Printing method
US3804660A (en) * 1970-08-17 1974-04-16 Commw Of Australia Dielectric recording on insulator surfaces
DE2154313A1 (de) * 1971-11-02 1973-05-10 Kalle Ag Verfahren zur herstellung von aufzeichnungen und hierzu geeignetes aufzeichnungsmaterial
US3808026A (en) * 1972-03-13 1974-04-30 Xerox Corp Liquid development of electrostatic latent image
US3836381A (en) * 1972-10-02 1974-09-17 Secretary Supply Australia Method of developing a dielectric pattern on a semiconductor surface using a two-component developer
US4496432A (en) * 1983-06-27 1985-01-29 At&T Technologies, Inc. Electrolytic methods for enhancing contrast between metallic surfaces
US6194108B1 (en) * 1996-10-17 2001-02-27 Fuji Xerox Co., Ltd. Image forming method and image forming device using same
US20050174549A1 (en) * 2004-02-09 2005-08-11 Asml Netherlands B.V. Lithographic apparatus and device manufacturing method
US7050146B2 (en) * 2004-02-09 2006-05-23 Asml Netherlands B.V. Lithographic apparatus and device manufacturing method
USRE42849E1 (en) 2004-02-09 2011-10-18 Asml Netherlands B.V. Lithographic apparatus and device manufacturing method

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GB1221347A (en) 1971-02-03
DE1622954A1 (de) 1970-12-03
FR1561533A (fr) 1969-03-28
BE712127A (fr) 1968-07-15

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