US3346475A - Electrophotographic method using an unsymmetrical ac current during development - Google Patents

Electrophotographic method using an unsymmetrical ac current during development Download PDF

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US3346475A
US3346475A US346184A US34618464A US3346475A US 3346475 A US3346475 A US 3346475A US 346184 A US346184 A US 346184A US 34618464 A US34618464 A US 34618464A US 3346475 A US3346475 A US 3346475A
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image
photoconductor
toner
electrode
unsymmetrical
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US346184A
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English (en)
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Matkan Josef
Robert A Chapman
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Research Laboratories of Australia Pty Ltd
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Australia Res Lab
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Priority claimed from AU27714/63A external-priority patent/AU279978B2/en
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    • 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
    • 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
    • G03G13/06—Developing
    • G03G13/10—Developing using a liquid developer, e.g. liquid suspension
    • 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

  • ABSTRACT OF THE DISCLOSURE This invention relates to the process of reproducing images and in particular it relates to a process wherein images are obtained by rendering visible memory effects produced in semiconductors.
  • Semiconductors are substances which are generally characterised by their electrical conductivity being variable by external factors such as for instance electromagnetic radiation.
  • One particular type of semiconductors is known as photoconductors.
  • photoconductors When a photoconductive substance is irradiated by a source of lightor X-rays, the electrical conductivity of the photoconductive substance increases Within certain limits in proportion with the intensity of such incident radiation. Because of this property photoconductors are used in the art of printing and in particular in electrophotography and xerography, both of which are generally within the scope of the art of elec-. trostatic printing. v
  • Electrostatic printing in its widest form can be (let scribed as a process wherein an insulating surface is provided with an electrostatic charge pattern in selective areas conforming to an image and wherein such charge pattern is subsequently rendered visible by applying a dry developer powder or a developer material suspended in an insulating liquid dispersant in order that such developer may be attracted and held electrostatically to the charged areas contained on the insulating surface.
  • the developed image may be fixed to the surface of the insulator or transferred to another surf-ace and fixed thereon, if desired.
  • Electrophotography is a special case of electrostatic printing and usually it involves the following process: A relatively conductive backing member such as metal'or paper sheet having deposited thereon a photoconductive material, such as for instance vitreous selenium or a particulate photoconductor such as for instance zinc oxide or lead monoxide and the like in a resin matrix, is subjected to a corona discharge whereby a uniform electro static charge is deposited onto the photoconductive layer. Such charged photoconductive layer is then exposed to a light or X-ray pattern whereby the irradiated areas he: come discharged whereas the shielded areas remain 3,346,475 Patented Oct. 10, 1967 ice charged and thus form a latent electrostatic image.
  • a photoconductive material such as for instance vitreous selenium or a particulate photoconductor such as for instance zinc oxide or lead monoxide and the like in a resin matrix
  • Such latent electrostatic image is then rendered visible by applying a dry developer powder or a developer material suspended in an insulating liquid dispersant in order that such developer may be attracted and held electrostatically to the charged areas.
  • the developed image may be fixed to the surface of the photoconductor or it may be transferred to another surface and fixed thereon, if desired.
  • xerography is generally used in connection With selenium as the photoconductor and dry powder developers in an electrophotographic process as hereinbefore described.
  • electrostatic printing and in particular electrophotography and xerography are based es-' sentially on the existence of an electrostatic charge in imagewise configuration upon an insulating surface and therefore all these processes involve in the first instance the step of depositing an electrostatic charge onto such insulating surface and then, as in the cases of electrophotography and xerography, modifying such electrostatic charge imagewise. It will be also noted that in electrostatic printing, in electrophotography and in xerography a latent electrostatic image is rendered visible by the application of particulate developer material which is attractable by the electrostatic charge existing on the insulating surface.
  • the present invention relates to a method wherein an image is formed on a photoconductor or semiconductor surface by selective deposition onto such surface of toner material or other medium in accordance with a conductivity pattern or memory effect contained by such surface, and wherein such deposition of toner material takes place preferentially in a dielectrophoretic cell in which however the potentials applied are insufficient to impress a charge on the photoconductor or semiconductor held in such cell.
  • the image is formed by the deposition of visually detectable matter under the influence of a low voltage field such field itself being controlled in intensity by the variance in conductivity of a pattern producing member. Consequently, the visible image produced corresponds to the pattern of conduc, tivity variance or memory effect existing on the pattern producing member.
  • the pattern controlling medium can conveniently be formed by exposure to light or X-rays of a photoconductor which exposure changes the resisitivityof such photoconductor in proportion to the intensity of the incident radiation and whereby such change in the resistivity of the photoconductor persists at least for some finite time after cessation of such exposure'as is known as a memory effect in relation to semiconductors.
  • the photoconductor then forms the controlling means for the deposition of the toner or the like.
  • X-ray patterns may be projected on to-the cell while visual image formation is effected or one of the electrodes may be transparent to allow a light image to be produced on the photoconductor sheet simultaneously with such imaging action.
  • the photoconductive element can comprise a photoconductive film deposited on a relatively conducting backing such as metal plate or foil or paper and the like.
  • the photoconductive film can be a layer of selenium or of an organic photoconductor, or it can be also a film comprising a particulate photoconductor such 'as for instance zinc oxide, cadmium selenide, lead monoxide and the like dispersed in an insulating medium such as a resin binder.
  • Such photoconductive film can also contain sensitising dyes for the purpose of increasing the response of such film to certain desired parts of the electromag netic spectrum. It is also possible to deposit such photo conductive film directly onto one of the electrodes contained in the dielectrophoretic cell.
  • the actual method of forming the image will thus be seen to consist in either using the memory effect of a photoconductor medium which has previously had a pattern exposed thereon, or to expose the photoconductor medium to a light pattern or an X-ray pattern or other condition at the time that imaging is being effected, such imaging being in each case effected by placing the photoconductive element into a dielectrophoretic cell containing two electrodes which are spaced a small distance apart, the photoconductive element being held against one of the electrodes and having the photoconductive layer exposed towards the other electrode, both such electrodes and the photoconductive element being immersed in an electrically insulating liquid in which are suspended toner particles or other means which can be moved under the influence of an electrostatic field, the image formation being effected by connecting the electrodes to a supply of electrical current of the type as will be described in the following disclosure.
  • the insulating liquid contained in the dielectrophoretic cell as referred to in the foregoing can be for instance a hydrocarbon solvent of high electrical volume resistivity such as for instance not less than ohm centimeters and of low dielectric constant such as less than 3.
  • suspended toner particles which may comprise pigments or other means which can be moved under the influence of an electrostatic field and such toner suspension may also contain other matter such' as for instance oils or resins or varnishes the presence of which may be formed to be desirable for instance to aid the dispersion of the toner material.
  • Such suspended matter or such toner particles in accordance with the present invention are characterised by being polarity sensitive, that is such particles have a tendency when in suspension to become attracted or repelled preferentially by electrostatic charges or an electrode of a certain polarity.
  • Toner or particle suspensions of this nature are substantially similar to liquid developers as known in the art of electrophotography.
  • the toner deposition is effected by the influence of an electrostatic field which is established by connecting the said electrodes to a power supply and the output of such power supply in one embodiment of this invention can be a direct current or a pulsating direct current whereas in another embodiment of this invention such output can be a symmetrical alternating current, in the case of a photoconductor of particular rectifying properties, or an unsymmetrical pulsating current of unequal magnitude, that is to say the pulsation may have a bias of either a positive or negative potential applied either in magnitude or in time.
  • a square wave can for instance be generated which has its datum line displaced from the central position of the wave so that one pulse will be stronger than the other pulse by reason of the greater amount of displacement, or alternatively the pulse can have an unequal time element so that the one crest is relatively long and the opposite remaining crest of that wave is relatively short, in both cases the effect being to favour either the positive or the negative pulse in amplitude or time.
  • FIG. 1 is a view showing the exposure of the photoconductor sheet to light to produce the memory image
  • FIG. 2 shows how the electrical cell in which development then takes place is made up, the generator producing either direct current or biased alternating current,
  • FIG. 3 shows how exposure and development can be effected simultaneously
  • a light source 1 projects an image from a" film 2 through a lense 3 on to a photoconductor film 4 on a backing member Ssuch as a sheet of paper.
  • the generator 7 is coupled to the back electrade 8 and to the front electrode 9 which are spaced apart and are immersed in a liquid 10 in tank 11, the image to be developed being in the form of a latent memory effect that is to sayin the form of a conductivity pattern on the photoconductor film 4 of the backing 5 resting on the back electrode 8.
  • the invention applies to that type of cell in which there. is a gap between the front electrode 9 and the photoconductive film 4, which gap is filled with an insulating liquid 10 in which the toner particles, which are to be moved for developmental purposes, are suspended.
  • Such modified field between the electrodes causes the toner particles to deposit onto the photoconductive layer substantially in conformity with the field intensity whereby an image is formed on such layer corresponding in density to the strength of such electrical field, such deposition of toner or other particulate means being substantially a dielectrophoretic process.
  • the dielectrophoretic cell in accordance with this invention is not to be mistaken for a type of cell which has been proposed heretofore in which an essentially conductive dry toner dust was used which itself formed the electrode, the toner dust being in that case applied at least at the front of the photoconductor sheet and itself forming as it were the front electrode, there being no insulating liquid between the face of the photoconductor film on which the latent image is contained and the electrode which effects development.
  • the preferred method is to use that contained in FIGS. 1 and 2 but if it is desired the procedure can be altered by combiuing the process of FIGS. 1 and 2 into that shown in FIG. 3 in which the various integers bear the same reference numerals as in FIGS. 1 and 2 but the light acts simultaneously with the generation of the depositing voltage, in this case the top electrode 9 of course being transparent to allow the image to be projected therethroug-h on to the photoconductor film 4, the top electrode being a grid which oscillates or as said being otherwise arranged in such a manner that the light or electromagnetic radiation image can pass therethrough.
  • the invention will operate if a direct current potential is applied which has the required polarity to move the particles under the influence of the induced field to those areas of higher conductivity where the field current can more readily flow through the photoconductor and thus it Will 'be noted that the rate of toner deposition and consequently the image density on the photoconductive layer is proportional to the conductivity of such layer, that is the image density is proportional to the intensity of radiation to which the photoconductive layer was previously exposed, the resulting image being therefore a reversal of such as for instance a positive to negative reproduction of the original radiation pattern.
  • FIGS. 4 and 5 The types of alternating Waves which can be elfectively used in this invention are shown in FIGS. 4 and 5, FIG. 4 showing how an ordinary square Wave can have its datum line displaced from the centre of the wave so as to give a lower amplitude 14 on the one side of the datum line 15 and a high amplitude 16 on the other side thereof.
  • FIG. 5 is shown a square wave which is symmetrical about the datum line 17, and in which the complete cycle 18 is shown broken up into a longer portion 19 and a shorter portion 20 so that there is a variation in time of the positive and negative pulses.
  • the toner material to be used in combination with the intensity and type of the pulsating current to be applied to the electrode depends on the electrical characteristics of the photoconductive element preferred. If for instance the photoconductive element contains inc oxide which is an n-type photoconductor and'is characterized by rectifying properties in that its resistivity is substantially higher when biased in one direction than in the other direction, the toner material preferred in this embodiment is one which is capable of being repelled by negative electrostatic charges or by a negative electrode or consequently one which can be attractive by positive electrostatic charges or by a positive electrode.
  • the pulsating current is applied to the electrode in such manner that the total energy of negative pulses appearing on the front electrode facing the photosensitive layer is higher than the total energy of the negative pulses appearing on the rear electrode located behind the photoconductive element.
  • an electrostatic field through the photoconductive element is established between the two electrodes and in eifect the photoconductive element is in this case in a reverse biased position.
  • the intensity of such electrostatic field is controlled locally by the conductivity pattern on the photoconductive element in that highest field intensity exists in the higher conductive exposed areas.
  • Deposition of the polarity sensitive toner material takes place in the high field intensity regions onto the conductive exposed areas of the photoconductive element by repulsion from the front electrode and/or by attraction from the rear electrode.
  • toner material will also deposit to some degree onto the unexposed areas causing objectionable background and diminishing contrast.
  • the electrostatic field through the photoconductive element becomes reversed between the electrodes. The overall intensity of such reversed electrostatic field is lower than that of the preceding electrostatic field due to the lower energy pulses appearing on both electrodes effecting such reversed field.
  • Toner material deposition at a lower rate takes place in presence of such lower intensity reversed field away from the photoconductive element and onto the positive front electrode and since the photoconductive element is in this case in a forward biased position so that the conductivity pattern has no influence on the field intensity, such deposition of toner material onto the front electrode is essentially uniform over the whole area facing the photoconductive element and the effect of such toner deposition onto the front electrode is uniform removal of toner material from the photoconductive element.
  • FIGS. 8 and 9 are shown the effects when a negative toner 32 is used.
  • FIG. 8 is shown the attraction during the positive cycle, that is when the backing plate 27 is positive and the photoconductor paper 30 is in reverse biased position.
  • FIGS. 6 and 7 a first case therefore, that is FIGS. 6 and 7, a
  • Both types of such papers comprised a relatively conducting paper backing having deposited thereon a photoconductive film containing zinc oxide dispersed in a resin binder.
  • Samples of the two types of papers were first dark rested for 48 hours and then a separate sample of each type was exposed in part to visible light emitted from a 100 watt incandescent globe, to ultraviolet radiation and the X-rays generated by a tube operating in the range between 50-100 kvp. Numerous exposures of varying duration were made and also the current in the X-ray tube was varied.
  • the papers were exposed to a light or radiation pattern for the purpose of forming a memory effect or a corresponding pattern of conductivity variance and the papers were processed in'the arrangements as shown in FIGS. 1, 2 and 3.
  • the image formation was effected by employing toner dispersions of the required polarity, and formulations of such toner materials are given following the examples.
  • the toner concentration was approximately that given in the formulations in which case the bulk resistivity between the electrodes as measured across the liquid toner dispersion was 10 ohms per square centimeter, which, as will be noted, is below the resistivity of either of the papers so that the conductivity pattern in the paper was capable of controlling the field between the electrodes.
  • the electrodes were spaced 3.5 mm. apart.
  • Example 1 A reversed image was formed on the type A paper employing direct current. The potential was 36 volts negative on the front electrode, 40 seconds developing time. A high intensity image was obtained with no objectionable background contamination.
  • Example 2 In Example 1 thepotential was raised to 250 volts and the developing time was reduced to 5 seconds. The resulting image was substantially similar to that of Example 1.
  • Example 3 A reversed image was formed on the type B paper employing direct current. The optimum result was obtained with a potential of 150 volts negative on the front electrode and a developing time of 15 seconds. Due to the relatively small difference in the conductivity of the exposed and unexposed areas the image contrast was poor and heavy background staining occurred.
  • Example 4 A high contrast reversed image with clean background was obtained on the type B paper employing anunsymmetrical alternating current as shown in FIG. 4 with a pulse duration of 150 milliseconds. E1 and E2 were 525 volts and 175 volts, respectively, E1 being the depositing pulse of negative polarity on the front electrode. Developing time was 30 seconds.
  • Example 6 A high contrast facsimile image with clean background was formed on the type B paper employing an unsymmetrical alternating current as shown in FIG. 4 with a pulse duration of 150 milliseconds. E1 and E2 were 540 and volts, respectively, E2 being .the depositing pulse of positive polarity on the front electrode. Developing time was 45 seconds.
  • Example 7 A high contrast reversed image with clean background 'was formed on the type A paper employing an unsymmetrical alternating current as shown in FIG. 4 with a pulse duration of milliseconds. E1 and E2 were 450 volts and 250 volts, respectively. E1 being the depositing pulse of negative polarity on the front electrode. Developing time was 45 seconds.
  • Example 8 A high contrast facsimile image with clean background was formed on the type A paper employing an unsymmetrical alternating current as shown in FIG. With a peak potential of 1400 volts and 30 seconds developing time, T1 and T2 were in the ratio of 400: 100 milliseconds with T2 as the depositing positive pulse on the front electrode.
  • the power supply for the purposes of this invention may comprise a simple set of dry cells arranged as a battery to supply the voltage required in case it is desired to operate on direct current and it is also possible to obtain direct current by rectifying alternating current or from any other source commonly known.
  • the unsymmetrical alternating current may be obtained from the commonly known multivibrator circuit as shown in the following but it is also possible to obtain such current from any other source of low frequency alternatingcurent wherein it is possible to vary either the datum line of the wave or the duration of each of the positive and negative parts of the wave.
  • the unsymmetrical alternating current may be obtained as the output from the anodes of a multivibrator or similar circuit.
  • a suitable amplifier circuit which has a low output impedance and is economical of current and which can be combined as a symmetrical pair connected to form a multivibrator may comprise a pair of tubes connected in series so far as their operation is concerned, but a resistance is placed between the cathode of the one valve and the anode of the other, the latter valve having a signal applied to its grid and the grid of the second valve being fed from the anode of this first valve, the output being taken from the cathode of the second valve.
  • V1 and V3 are grounded cathode amplifiers with their static loads formed by V2 and V4.
  • the dynamic load of V1 and V3 is the input impedance of V2 and V4 and as such impedance is very high, the actual gain obtained from V1 and V3 approaches the maximum theoretical value for the particular valve type used.
  • the valves of each pair need not be identical valve types.
  • the switching speed is very high and the output impedance is low and the average current drawn is also low.
  • pulse length being controlled by the values of C1 and C2 and also by the potential to which the grid resistors Rgl and Rg2 are returned.
  • the pulse output is very nearly the rail potential.
  • a transistorised pulse generator can be used. Development time however will be in such case substantially longer as the maximum pulse voltage obtainable from commercially available transistors is considerably lower than that from valves.
  • toners which are polarity sensitive and can be used in accordance with this invention.
  • Black toner This is a so called negative toner which is used for reversal reproduction, attracted by positive polarity charges or by a positive electrode.
  • the ingredients are milled to form a paste.
  • the toner dispersion is prepared by stirring approximately 10 grams of this paste into 500 cc. of any one of the following liquids or into the mixture of such: Shell Solvents X4 and X55, Shellsol T and trichlorotrifiuoroethane.
  • Blue toner This is also a so called negative toner which is used for reversal reproduction.
  • the toner particles are attracted by positive polarity charges or by a positive electrode.
  • roller electrodes of the plate type could carry the photoconductor sheet or the like while another, or a simple fixed electrode, could be positioned in relation thereto to give the necessary field for image deposition on the rotating roller.
  • the invention can also be used by producing an image in such a way that it can then be transferred, that is to say the image can be formed by an imaging material or coating medium which remains in a mobile state for a sufficient time to allow the image to be transferred after formation and subsequently fixed to another base.
  • the image can be formed on a sheet containing a film of semiconductor or photoconductor such sheet being placed between the electrodes in a manner as hereinbefore described, or alternatively such image can be formed directly on one of the electrodes of the cell in which case such electrode can itself carry a film of semiconductor or photoconductor substance at least on the side adjacent to the electrode of opposite polarity.
  • Microlith Black CT is a resinated carbon black pigment produced by Ciba.
  • Fastel Pink B Supra is an organic red pigment produced Staybelite Resin is a hydrogenated rosin produced by Hercules Powder C0.
  • Shell X4 is a substantially aliphatic hydrocarbon solvent, sp. gr. 0.67, boiling range 5870 C., KB value 30,
  • Shell X55 is a. substantially aliphatic hydrocarbon solvent, -sp. gr. 0.72, boiling range 58-140 C., KB value 40, produced by Shell Chemicals. e
  • Shellsol T is 'an aliphatic hydrocarbon solvent, sp. gr.

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US346184A 1963-02-25 1964-02-20 Electrophotographic method using an unsymmetrical ac current during development Expired - Lifetime US3346475A (en)

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Cited By (28)

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US3527684A (en) * 1967-03-13 1970-09-08 Eastman Kodak Co Method of increasing contrast in electrophoretic reproduction
DE2020726A1 (de) * 1969-04-23 1970-12-10 Matsushita Electric Ind Co Ltd Elektrophoretisches Lichtbildwiedergabeverfahren
DE2020733A1 (de) * 1969-04-23 1970-12-10 Matsushita Electric Ind Co Ltd Vorrichtung zur elektrophoretischen Wiedergabe von Lichtbildern
US3782818A (en) * 1972-11-17 1974-01-01 Savin Business Machines Corp System for reducing background developer deposition in an electrostatic copier
US3784397A (en) * 1970-02-04 1974-01-08 Xerox Corp Imaging system
FR2217738A1 (fr) * 1973-02-15 1974-09-06 Xerox Corp
JPS49126856U (fr) * 1973-02-15 1974-10-30
US3853555A (en) * 1972-11-28 1974-12-10 Xerox Corp Method of color imaging a layer of electrically photosensitive agglomerates
JPS5030537A (fr) * 1973-02-15 1975-03-26
US3901696A (en) * 1972-06-30 1975-08-26 Turlabor Ag Electrode-shunting method of producing electrophotographic pictures and apparatus therefor
US3941593A (en) * 1971-09-12 1976-03-02 William Alan Stewart Butement Electro-photographic method and element
FR2291531A1 (fr) * 1974-11-18 1976-06-11 Oce Van Der Grinten Nv Dispositif pour transferer electrostatiquement une image de poudre d'un support sur une matiere receptrice
JPS5316291B1 (fr) * 1971-02-09 1978-05-31
US4093456A (en) * 1975-06-25 1978-06-06 Konishiroku Photo Ind., Ltd. Process and device for electrophotographic image generation and application of the process
US4168975A (en) * 1976-06-17 1979-09-25 Repco Limited Electrophotographic image receiving plates
DE2916320A1 (de) * 1978-04-24 1979-10-31 Coulter Systems Corp Verfahren bzw. einrichtung zur entwicklung von latenten elektrostatischen ladungsbildern
JPS5518656A (en) * 1978-07-28 1980-02-08 Canon Inc Electrophotographic developing method
EP0023231A1 (fr) * 1979-07-27 1981-02-04 Tabarelli, Werner, Dr. Procédé de lithographic optique et dispositif pour copier un dessin sur une plaquette semiconductrice
US4292387A (en) * 1978-07-28 1981-09-29 Canon Kabushiki Kaisha Magnetic developing method under A.C. electrical bias and apparatus therefor
EP0041276A1 (fr) * 1980-06-03 1981-12-09 Coulter Systems Corporation Procédés de transfert de dépôts d'image formés de particules de marquage électroscopiques
US4322488A (en) * 1978-04-24 1982-03-30 Coulter Systems Corporation Developing latent electrostatic images using a liquid toner and a development electrode
US4395476A (en) * 1978-07-28 1983-07-26 Canon Kabushiki Kaisha Developing method for developer transfer under A.C. electrical bias and apparatus therefor
EP0087840A1 (fr) * 1982-03-02 1983-09-07 Océ-Nederland B.V. Machine à photocopier électrophotographique
US4473627A (en) * 1978-07-28 1984-09-25 Canon Kabushiki Kaisha Developing method for developer transfer under electrical bias and apparatus therefor
US4675267A (en) * 1981-02-25 1987-06-23 Konishiroku Photo Industry Co., Ltd. Method of developing electrostatic images using two component developer and AC charging
US5032485A (en) * 1978-07-28 1991-07-16 Canon Kabushiki Kaisha Developing method for one-component developer
US5194359A (en) * 1978-07-28 1993-03-16 Canon Kabushiki Kaisha Developing method for one component developer
US20080131613A1 (en) * 2006-11-30 2008-06-05 Jones Thomas B Fluid management system and method for fluid dispensing and coating

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US2892709A (en) * 1955-03-07 1959-06-30 Gen Dynamics Corp Electrostatic printing
US2976144A (en) * 1958-10-24 1961-03-21 Rca Corp Electrophotography
US2978968A (en) * 1958-04-14 1961-04-11 Haloid Xerox Inc Recording apparatus and method
US3043684A (en) * 1955-01-26 1962-07-10 Gen Dynamics Corp Electrostatic printing
US3084043A (en) * 1959-05-07 1963-04-02 Xerox Corp Liquid development of electrostatic latent images
US3100426A (en) * 1960-04-26 1963-08-13 Edward K Kaprelian Electrophotographic printers
US3212890A (en) * 1955-09-30 1965-10-19 Minnesota Mining & Mfg Photoconductive element for use in electrophotography containing a heavy metal soap of a long chain fatty acid; and process for using same
US3245381A (en) * 1961-04-19 1966-04-12 Agfa Ag Developing apparatus

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US3043684A (en) * 1955-01-26 1962-07-10 Gen Dynamics Corp Electrostatic printing
US2892709A (en) * 1955-03-07 1959-06-30 Gen Dynamics Corp Electrostatic printing
US3212890A (en) * 1955-09-30 1965-10-19 Minnesota Mining & Mfg Photoconductive element for use in electrophotography containing a heavy metal soap of a long chain fatty acid; and process for using same
US2978968A (en) * 1958-04-14 1961-04-11 Haloid Xerox Inc Recording apparatus and method
US2976144A (en) * 1958-10-24 1961-03-21 Rca Corp Electrophotography
US3084043A (en) * 1959-05-07 1963-04-02 Xerox Corp Liquid development of electrostatic latent images
US3100426A (en) * 1960-04-26 1963-08-13 Edward K Kaprelian Electrophotographic printers
US3245381A (en) * 1961-04-19 1966-04-12 Agfa Ag Developing apparatus

Cited By (37)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3527684A (en) * 1967-03-13 1970-09-08 Eastman Kodak Co Method of increasing contrast in electrophoretic reproduction
DE2020726A1 (de) * 1969-04-23 1970-12-10 Matsushita Electric Ind Co Ltd Elektrophoretisches Lichtbildwiedergabeverfahren
DE2020733A1 (de) * 1969-04-23 1970-12-10 Matsushita Electric Ind Co Ltd Vorrichtung zur elektrophoretischen Wiedergabe von Lichtbildern
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NL6401766A (fr) 1964-08-26
BE644307A (fr) 1964-06-15

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