EP0423158B1 - Doppelfarbbildverfahren und vorrichtung - Google Patents

Doppelfarbbildverfahren und vorrichtung Download PDF

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Publication number
EP0423158B1
EP0423158B1 EP89906820A EP89906820A EP0423158B1 EP 0423158 B1 EP0423158 B1 EP 0423158B1 EP 89906820 A EP89906820 A EP 89906820A EP 89906820 A EP89906820 A EP 89906820A EP 0423158 B1 EP0423158 B1 EP 0423158B1
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EP
European Patent Office
Prior art keywords
image
charge
pigmented particles
particles
liquid
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.)
Expired - Lifetime
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EP89906820A
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English (en)
French (fr)
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EP0423158A1 (de
Inventor
Benzion Landa
Yehuda Niv
Israel Grossinger
Yossi Adam
Moshe Levanon
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HP Indigo BV
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Indigo BV
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Filing date
Publication date
Priority claimed from US07/202,677 external-priority patent/US4966824A/en
Priority claimed from US07/202,514 external-priority patent/US5121164A/en
Priority claimed from US07/202,322 external-priority patent/US4947201A/en
Priority claimed from US07/202,688 external-priority patent/US5108866A/en
Priority claimed from US07/268,855 external-priority patent/US5012300A/en
Application filed by Indigo BV filed Critical Indigo BV
Publication of EP0423158A1 publication Critical patent/EP0423158A1/de
Application granted granted Critical
Publication of EP0423158B1 publication Critical patent/EP0423158B1/de
Anticipated expiration legal-status Critical
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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
    • G03G13/06—Developing
    • G03G13/10—Developing using a liquid developer, e.g. liquid suspension
    • 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
    • G03G13/01—Electrographic processes using a charge pattern for multicoloured copies
    • G03G13/013—Electrographic processes using a charge pattern for multicoloured copies characterised by the developing step, e.g. the properties of the colour developers
    • G03G13/0131—Electrographic processes using a charge pattern for multicoloured copies characterised by the developing step, e.g. the properties of the colour developers developing using a step for liquid development, e.g. plural liquid color developers
    • 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
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/10—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer
    • G03G15/104—Preparing, mixing, transporting or dispensing developer
    • 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

  • the present invention relates to an imaging apparatus according to the preamble of claim 1.
  • U.S. Patent No. 4,264,185 (Ohta) describes a process in which areas of an electrostatic latent image corresponding to two colors in an original document are developed. Ohta's process applies toners of different colors and polarities to the latent image, using separate mechanisms. In order to repel other, undesired toner particles from one development unit, a bias voltage of opposite polarity is applied to the latter unit, and vice-versa.
  • Ohta's process may use separate baths of the two toners, or a single partitioned bath with liquid communication between the compartments. Even where a single partitioned bath is used, the latent image is developed in two distinct steps. It is unclear from the disclosure in this patent how the question of clean-up of the background is to be dealt with, if at all.
  • a toner of 14 microns mean particle size and resistivity of at least 1015 ohm-cm, triboelectrically chargeable to positive polarity, comprised styrene-acrylic copolymer (100) and red colored charge controlling pigment (5); while a carrier of 20 microns mean particle size, resistivity of 1014 ohm-cm, triboelectrically chargeable to negative polarity, comprised styrene-acrylic copolymer (100), magnetic fine powder (200), carbon black (4) and silica fluidity agent (1.5); parts indicated in parentheses are by weight.
  • the developer comprised a 1:9 mixture of toner and carrier.
  • U.S. Patent 4,411,976 describes a method of increasing the density of liquid developed gap transferred electrophotographic images and developing composition for use therein wherein the carrier sheet is heated either before or after transfer to a temperature less than 100 degrees C at which the binder or polymer forming the toner particles will solvate the liquid entrained in the transferred image to increase the density of the image.
  • the present invention seeks to provide an improved imaging system and process.
  • an imaging system comprising means for forming a latent image on a surface, the latent image including a first portion having a high level of electrostatic charge, a second portion having a low level of electrostatic charge and a third portion having an intermediate level of electrostatic charge, means for developing the latent image by contacting it with a liquid toner composition comprising an insulating, nonpolar liquid having admixed therewith at least one charge director, a first type of pigmented particles having charges of a first polarity and a second type of pigmented particles having charges of an opposite polarity, such that the first type of pigmented particles becomes deposited onto the first portion and the second type of pigmented particles becomes deposited onto the second portion, and means for regulating the concentration of the at least one charge director in the liquid toner composition.
  • an imaging system comprising means for forming a latent image on a surface, the latent image including a first portion having a high level of electrostatic charge, a second portion having a low level of electrostatic charge and a third portion having an intermediate level of electrostatic charge, means for developing the latent image by contacting it with a liquid toner composition comprising an insulating, nonpolar liquid having admixed therewith a first type of pigmented particles having charges of a first polarity and a second type of pigmented particles having charges of an opposite polarity, such that the first type of pigmented particles becomes deposited onto the first portion and the second type of pigmented particles becomes deposited onto the second portion and means for removing unwanted pigmented particles from a region of the developed image defined by the third portion, the means for removing comprising first removal means biased at a potential between (i) the average surface potential of the third portion and (ii) the potential of the first portion, for the removal of the
  • an imaging system comprising means for forming a latent image on a surface, the latent image including a first portion having a high level of electrostatic charge, a second portion having a low level of electrostatic charge and a third portion having an intermediate level of electrostatic charge and means for developing the latent image by contacting it with a liquid toner composition comprising an insulating, nonpolar liquid having admixed therewith at least one charge director, a first type of pigmented particles having charges of a first polarity and a second type of pigmented particles having charges of an opposite polarity, such that the first type of pigmented particles becomes deposited onto the first portion and the second type of pigmented particles becomes deposited onto the second portion, wherein the at least one charge director comprises first and second charge directors and wherein the charges of the first polarity on the first type of pigmented particles are induced by the first charge director and the charges of the opposite polarity on the second type of pigmented particles are
  • the toner composition also includes at least one charge director and the system also comprises means for regulating the concentration of the at least one charge director in the liquid toner composition.
  • the system also comprises means for removing unwanted pigmented particles from a region of the developed image defined by the third portion, the means for removing unwanted pigmented particles comprising first removal means biased at a potential between (i) the average surface potential of the third portion and (ii) the potential of the first portion, for the removal of the first type of pigmented particles from the third portion, and second removal means biased at a potential between (i) the average surface potential of the third portion and (ii) the potential of the second portion, for the removal of the second type of pigmented particles from the third portion.
  • the at least one charge director comprises first and second charge directors and the charges of the first polarity on the first type of pigmented particles are induced by the first charge director and the charges of the opposite polarity on the second type of pigmented particles are induced by the second charge director.
  • the means for developing comprises a development electrode biased at an electrostatic potential level near to the surface potential of the intermediate level of electrostatic charge.
  • the charges of the first polarity on the first type of pigmented particles and the charges of the opposite polarity on the second type of pigmented particles are induced by the at least one charge director.
  • the at least one charge director comprises first and second charge directors and the means for regulating the concentration of the at least one charge director in the liquid toner composition comprises means for separately regulating the concentrations of the first and second charge directors.
  • an imaging process comprising the steps of forming a latent image on a surface, the latent image including a first portion having a high level of electrostatic charge, a second portion having a low level of electrostatic charge and a third portion having an intermediate level of electrostatic charge, the charges on the first, second and third portions being of the same polarity, and developing the latent image by contacting it with a liquid toner composition comprising an insulating, nonpolar liquid having admixed therewith a first type of pigmented particles having charges of a first polarity and a second type of pigmented particles having charges of an opposite polarity, such that the first type of pigmented particles becomes deposited onto the first portion and the second type of pigmented particles becomes deposited onto the second portion.
  • a dual color imaging process which comprises the steps of forming an image having adjacent first and second areas respectively containing first and second types of pigmented resin, undesirably separated by third areas relatively free of resin of the first and second types, and causing the image to flow into the third areas, thereby at least partially eliminating the third areas.
  • the step of causing comprises the step of heating the image.
  • the image is produced by employing a liquid toner composition which comprises an insulating, nonpolar liquid having admixed therewith two different particulate pigments carrying opposite charges.
  • the particulate pigments comprise at least one binder wax.
  • the particulate pigments also comprise at least one polymeric material.
  • the at least one polymeric material comprises an ethylene copolymer including carboxylic acid functionality.
  • liquid toner composition for use in development of a latent electrostatic image in an electrostatic imaging process, which comprises an insulating, nonpolar, nontoxic liquid having admixed therewith two different particulate pigments carrying charges which are opposite from each other, wherein the composition comprises also at least one charge director which promotes charging of the two particulate pigments in an opposite sense, respectively.
  • the composition also comprises at least one polymeric carrier for the particulate pigments.
  • the at least one charge director comprises a single charge director.
  • the at least one charge director comprises two charge directors, which are effective to charge one of the two particulate pigments positively, and the other of the two particulate pigments negatively.
  • a process for preparing a liquid toner composition which comprises the step of combining first and second types of pigmented particles and at least one charge director to provide a liquid toner composition wherein the first type of pigmented particles acquire charges of a first polarity and the second type of pigmented particles acquire charges of a second polarity, opposite to the first polarity.
  • the step of combining also comprises the step of polarizing the first and second types of pigmented particles, whereby the first type of pigmented particles acquires charges of the first polarity and the second type of pigmented particles acquires charges of the second polarity.
  • the polarizing step may be effected either prior to, in the course of, or after combining the first and second types of pigmented particles with each other.
  • the at least one charge director is operative to cause the first type of pigmented particles to acquire charges of the first polarity and the second type of pigmented particles to acquire charges of the second polarity.
  • the at least one charge director comprises two charge directors, which are operative to cause the first type of pigmented particles to acquire charges of the first polarity and the second type of pigmented particles to acquire charges of the second polarity.
  • a method for maintaining first and second concentrations of respective first and second charge directors suspended in a toner composition comprising pigmented particles at respective given first and second values, the method comprising at least two of the following steps: (a) developing at least one color patch using the toner composition, obtaining measurements of the optical densities of the at least one color patch, (b) obtaining a measurement of the conductivity of a toner composition and comparing the conductivity measurement to a reference, (c) removing pigmented particles from a sample of the toner composition and measuring the amount of absorption of light of at least one given wavelength by the sample, determining the respective amounts of the first and second charge directors which need be added to the composition to restore the first and second concentrations of the first and second charge directors in the toner composition to the respective first and second given values; and adding the non-zero ones of the respective amounts of the first and second charge directors to the composition.
  • FIG. 1 there is shown electrostatic imaging apparatus employing a liquid toner composition comprising two oppositely charged and differently colored pigmented particles.
  • a metal drum 2 which carries a photoconductor 4 and which is mounted by disks 6 onto a shaft 8 to which the disks are secured by a key 10 so that the shown assembly, which is provided in a light-proof housing (not shown) is operative to rotate a shaft 8.
  • Shaft 8 is driven in any appropriate manner (not shown) in the direction of arrow 9 past a corona discharge device 12 adapted to charge the surface of the photoconductor 4.
  • the image to be reproduced is focused by a lens 14 upon the charged photoconductor. Since shaft 8 is grounded at 17 and disks 6 are conductive, the areas struck by light conduct the charge, or a portion thereof, to ground, thus forming an electrostatic latent image. Formation of the electrostatic latent image in this way is shown in Fig. 2A.
  • the developing liquid containing two different pigmented particles, as described herein, is circulated from any suitable source (not shown) through a pipe 16 into a development tray 18 from which it is drawn through a pipe 20 for recirculation.
  • photoconductor 4 is positively charged, e.g. if a selenium photoconductor is used, negatively charged pigmented particles 23 will travel to electrostatic latent image areas having generally the highest positive potential, here shown at 1000 V, while positively charged pigmented particles 25 will travel to the latent image areas having generally the lowest positive potential of near 0 V, typically 50 V to 100 V.
  • the background carries a charge of typically 500 V.
  • the photoconductor is negatively charged, e.g. if a cadmium sulfide photoconductor is used, negatively charged pigmented particles travel to electrostatic latent image areas having generally the lowest negative potential, while positively charged pigmented particles travel to the latent image areas having generally the highest negative potential.
  • the developed image from which excess liquid has been removed by a background clean-up unit 30 and which contains differently pigmented areas having respectively positive and negative charges, is passed under a corona discharge device 44, which imposes, for example, a negative DC electrical discharge so as to convert image areas of positive charge to a negative charge and image areas of negative charge to a relatively greater negative charge.
  • a corona discharge device 44 which imposes, for example, a negative DC electrical discharge so as to convert image areas of positive charge to a negative charge and image areas of negative charge to a relatively greater negative charge.
  • particles 23 now carry a greater negative charge than before and particles 25, which previously carried a positive charge, now carry a relatively small negative charge.
  • transfer of the image to a carrier sheet 100 may be effected, as described below in detail, by provision of a single corotron operative to charge the sheet to a polarity opposite to that of the developed image.
  • the negative DC electrical discharge may be combined with AC electrical discharge so as to narrow (or if desired to reduce to zero) the difference in surface potentials between the differently pigmented areas.
  • a pair of register rollers 32 and 34 is adapted to feed a carrier sheet 100, which is to receive the developed image, to a transfer station, where, as shown particularly in Fig. 2D, a corona discharge device 46 is operative to impress upon the rear of the carrier sheet a charge of polarity opposite to that of the toner particles forming the image after electrical treatment of the image by corona discharge device 44.
  • the developed image is thus drawn towards the carrier sheet by electrophoresis.
  • Rollers 32 and 34 are mounted onto and secured for rotation with respective axles 36 and 38.
  • a pick-off-member 48 assists in the removal of the carrier sheet bearing the developed image from the photoconductor. The image is then fixed onto carrier sheet 100 prior to delivery to an exit tray.
  • a cleaning roller 56 formed of any synthetic resin known to the art and appropriate for this purpose, is driven in a direction of rotation opposite to that of the photoconductor, to scrub clean the surface thereof.
  • insulating, nonpolar liquid may be fed through a pipe 58 to the surface of the cleaning roller 56.
  • a wiper blade 60 completes the cleaning of the photoconductive surface. Any residual charge left on the photoconductive drum is neutralized by flooding the photoconductor surface with light from a lamp 62.
  • a background clean-up unit referenced generally 30, comprises, according to the illustrated embodiment, a pair of rollers 74 and 76 which are rotated (by means not shown) on axles 78 and 80 respectively, in the indicated direction, counter to that of photoconductor surface 4 (arrow 9). Background clean-up unit 30 is also operative to remove excess liquid from the photoconductive surface 4, by virtue of the reverse rotation of roller 74 as indicated in Fig. 3.
  • the use of a reverse rotating roller for removal of excess liquid is described in U.S. Patent 3,907,423, the disclosure of which is incorporated herein by reference.
  • the image includes areas of negative black toner particles developed at 1000 volts positive potential, and areas of positive red toner particles developed at near zero potential and background areas having potential at 500 volts to which some red and black toner particles adhere.
  • Roller 74 is charged with a positive potential of, for example, 600 volts and thus attracts black particles from the background without detaching of red toner particles from the image.
  • Roller 76 is charged with a positive potential of, for example, 400 volts and thus attracts red particles from the background without detaching black toner particles from the image.
  • Rollers 74 and 76 are provided with respective wiper blades 82 and 84 for removal and transfer of adherent pigmented particles to circulating insulating, nonpolar liquid which may be fed into the clean-up unit through a pipe 70 and out through a pipe 72.
  • any pigmented particles suspended in the liquid are removed by a filter 31, which may be any type of conventional filtering apparatus suited for this purpose.
  • the filtered liquid may subsequently be recirculated into clean-up unit 30 via pipe 70. It is appreciated that due to the efficient cleaning activity of rollers 74 and 76 in the region therebetween and between photoconductor surface 4, it is possible to feed unfiltered liquid toner through pipe 70.
  • Rollers 74 and 76 are spaced about 50 to 200 microns apart, so that red particles repelled by roller 74 are attracted to roller 76 and black particles repelled by roller 76 are attracted to roller 74.
  • rollers 74 and 76 in the structure of Fig. 3 described above is operative to remove from the photoconductor surface particles from regions having voltages between 400 and 600 volts.
  • Fig. 6 it is noted that for two adjacent colored areas the transition of photoconductor voltages is not entirely sharp, as illustrated at A, but instead is more correctly represented by a curve B. Thus there are defined at the transitions between areas of black and red color, regions at which the voltage is between 400 and 600 volts. The width of these regions is indicated by D. At these regions, the operation of the background removal apparatus is effective to remove both the red and black toner particles thus producing undesired uncolored areas in these regions.
  • width D is relatively small, due to the fact that the undesired uncolored areas occur at a color transition, they are noticed by the human eye.
  • the insulating, nonpolar liquid used as the medium for toner particles as well as for other optional purposes as described herein, preferably has a resistivity in excess of about 109 ohm-cm and a dielectric constant below about 3.0.
  • Suitable such liquids are hydrocarbons, preferably aliphatic and more preferably isomerized aliphatic hydrocarbons, as, for example, those marketed by Exxon Corporation under such trade marks as ISOPAR-G, ISOPAR-H, ISOPAR-L and ISOPAR-M, which meet the preferred resistivity and dielectric requirements.
  • Polymers useful as binders for the pigmented particles may be thermoplastic.
  • the presently preferred polymers are known under the trade mark ELVAX II, manufactured by E.I. Du Pont de Nemours & Company.
  • the ELVAX II family are ethylene copolymers combining carboxylic acid functionality, high molecular weight and thermal stability.
  • the presently preferred ELVAX II resins are those designated 5720 and 5610.
  • Other polymers which may be used are the ELVAX polymers and the ethylene/ethyl acrylate series made by Union Carbide such as those designated DPD 6169, DPDA 6182 Natural and DTDA 9169 Natural.
  • Still other useful polymers made by Union Carbide are those designated DQDA 6479 Natural 7 and DQDA 6832 Natural 7; these are ethylene/ vinyl acetate resins.
  • the polymers are pigmented so as to render the latent image visible in two colors.
  • the pigments may be present generally in an amount of 1-60% by weight with respect to the weight of the polymer.
  • the selection of two pigments from the examples listed in the description which follows or/and from those otherwise known in the art may be readily performed by a person of ordinary skill in the art.
  • a toner liquid composition which comprises an insulating, nonpolar liquid having admixed therewith two different pigmented particles carrying opposite charges. It should be emphasized that the choice of colors of the pigmented particles is entirely at the discretion of the person operating the process, subject only to the condition that the pigmented particles should be adapted to be oppositely charged in the same medium.
  • Illustrative examples of potentially suitable pigments are Cabot Mogul L (black), Monastral Blue G (C.I. Pigment Blue 15 C.I. No. 74160), Quindo Magenta (Pigment Red 122), Indo Brilliant Scarlet Toner (Pigment Red 123, C.I. No. 71145), Dalamar Yellow (Pigment Yellow 74, C.I. No. 11741), blue pigment BT-383D (DuPont), yellow pigment YT-717D (DuPont), red pigment RT-455D (DuPont) and blue pigment Helioecht Blue GO (Bayer).
  • One of the two pigments may be, if desired, a finely ground ferromagnetic material, e.g. Mapico Black.
  • suitable materials are metals including iron, cobalt, nickel and various magnetic oxides including Fe2O3 and Fe3O4; and others known in the art. Mixtures of known magnetic materials may also be used.
  • the liquid toner composition employed may be prepared by a method which comprises the steps of: separately wet-grinding two pigments, which are respectively adapted to acquire charges of opposite polarities, preferably together with a thermoplastic polymeric binder for the pigments, in an inert medium until homogeneous and until the dispersed solids have predetermined characteristics selected from the group consisting of a desired particle size range and a fibrous structure; and polarizing the pigmented particles in the resultant wet-ground composition, whereby the pigmented particles acquire charges of opposite polarities, respectively.
  • the polarizing step is preferably carried out by addition of either one or two charge directors to the wet-ground composition, as otherwise described herein.
  • the liquid toner composition may be prepared (e.g.) by initially mixing a suitable polymer together with a plasticizer and separately with each of the two selected pigments, until homogeneity is achieved. Thereafter, the mixture is allowed to cool while mixing is continued.
  • the mixing temperature may range from about 65 to about 100°C, preferably about 90°C. Mixing times prior to cooling, typically about 90 minutes, may range between about 10 minutes and 3 hours.
  • Any suitable mixing or blending device may be employed, such as the Ross double planetary mixer (manufactured by Charles Ross & Son of Hauppauge, New York).
  • the mixture After the mixture has been cooled, it is charged to an attritor, disk mill, sand mill, impeller attrition mill, vibro-energy mill, or the like.
  • the liquid used during the grinding operation may be e.g., ISOPAR-H, which is present in an amount of 70-90% by weight in respect of the polymer.
  • the particle size is determined, for example, by centrifugal analysis using, e.g., a Horiba Centrifugal Particle Size Analyzer, Model CAPA 500, manufactured by Horiba Instruments Inc. of Irvine, California.
  • the ground material for each pigment is then dispersed e.g. in ISOPAR-H and mixed with a charge director to form a working dispersion having a solids content of about 0.5 to about 3% by weight.
  • the amount of charge director is dependent on its characteristics and the requirements of the use of the particular toner in question.
  • the working dispersions for both pigments are then combined or alternatively they may be combined prior to mixing with the charge director.
  • charge directors may be used in either one of two ways, in one of which a single charge director may be used to induce opposite charges on two different pigmented particles, respectively.
  • the use of a single charge director in conjunction with the selection of two suitable pigmented particles may be done as e.g. is illustrated in certain of the Examples, below.
  • two charge directors are used simultaneously in the same composition, whereby there is induced a positive charge on one species of particles and a negative charge on the other species of particles. Illustration of the use of two charge directors is given in certain of the Examples below.
  • Examples of charge directors which according to the prior art were regarded as inducing negative charges are e.g. magnesium, calcium and barium petronates; aluminum stearate, metal dialkylsulfosuccinates, other metal soaps such as copper oleate, and lecithin.
  • Examples of charge directors which according to the prior art were regarded as inducing positive charges are e.g. manganese naphthenate, manganese octoate, zirconium octoate and cobalt octoate.
  • Monitoring may be effected, for example, by measuring the optical density of the toner liquid as it passes through development tray feed pipe 16 (see also Fig. 1). This may be effected by way of two LEDs (light emitting diodes) referenced 92 and 94, emitting two different wavelengths of light and by a pair of connected light detectors, referenced 96 and 98, respectively.
  • LEDs light emitting diodes
  • the different light wavelength intensities are passed on, as in digital form, to a microprocessor 90, which contains information useful in correlating the different light wavelengths' intensities with concentrations of the two pigmented particles.
  • the information contained in the microprocessor may be compiled by means of studies on similar liquids containing known concentrations of the two pigmented particles.
  • black and blue pigmented particles are used and that the blue pigmented particle is blue light transparent and red light absorbing.
  • detector 96 utilizing blue light may thus be used to determine the concentration of black pigmented particles, while detector 98 utilizing red light may be similarly used to determine the total concentration of the two pigmented particles; thus the concentrations of both pigmented particles in the toner liquid may be determined.
  • microprocessor 90 upon receiving input from detectors 96 and 98 as described, microprocessor 90 is programmed to operate either or both pigmented particle pumps, respectively referenced 101 and 102, once it has determined that the concentration of either or both of the pigmented particles has fallen below a desired concentration. In this way, continuous regulation and, if necessary, replenishment, of the pigmented particles is possible.
  • this may be effected by compiling tables relating the conductivity of a toner liquid to various concentrations of the particular charge director therein and, when required, measuring the conductivity of operational toner liquid for determination of the charge director concentration by reference to the tables.
  • a further indication of the depletion of charge director(s) in the toner liquid may be obtained by developing patches of each color and measuring their optical densities. Optical densities which are too high indicate depletion of charge director(s), while the contrary is indicated by optical densities which are too low. Such information could be utilized in conjunction with that obtained from conductivity measurements and also from light measurements, as applicable.
  • the electrostatic latent image to be developed comprises areas of high, low and intermediate levels of electrostatic charge.
  • the electrostatic latent image to be developed comprises areas of high, low and intermediate levels of electrostatic charge.
  • the grey will be represented in the latent image by an intermediate charge level, while the white and black areas will be represented by the two other levels of charge.
  • the three charge levels could be generated, for example, by modulating the power of the exposing laser beams (in a laser printer) or the amount of charge which is supplied to a latent image holding substrate (in an electrostatic or ionographic printer).
  • the system described herein need not be applied to copy colors which are similar to those in a colored original.
  • a process including copying similar colors can be made feasible by the combined use of color filters, a reading element and a printing head, with the result that the colored original will be stored and used in the form of digital information which may be utilized so as to give the desired three level latent image.
  • the formulations therein were used to develop latent images from black and white Letraset originals which had either a grey or colored background.
  • the electrostatic imaging response of the photoconductor results in a latent image composed of areas of approximately 1300V (first color) and 50V (second color) on a 600V background.
  • the development bias was set at about 600V.
  • Example VIII When using the formulation of Example VIII, the developed image was transferred to paper using an additional pre-transfer corotron with a test copier configuration, and in addition a separate background cleaning station with clear liquid input, as described herein, was used.
  • the electrostatic imaging response of the photoconductor resulted in a latent image composed of areas of approximately 1000 Volts (first color), 50 Volts (second color) and a 500 Volt background.
  • the development bias was set at about 600 Volts and the cleaning rollers 74 and 76 in the configuration of Fig. 3 were set at positive 600 Volts and 400 Volts respectively.
  • the developed image in all cases may be subjected to fusing temperatures at about 120°C or higher on a hot plate fuser, in order to eliminate undesired relatively uncolored areas between adjacent colors.
  • a roll fuser configuration is used with some pressure, at about 100°C.
  • Examples I-IV and VI illustrate an embodiment of the invention in which a single charge director suffices for the two pigmented particles in the toner compositions to become oppositely charged.
  • Examples V, VII and VIII illustrate an embodiment of the invention in which two charge directors are used to render the two pigmented particles in the toner compositions oppositely charged.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Liquid Developers In Electrophotography (AREA)
  • Color Electrophotography (AREA)
  • Wet Developing In Electrophotography (AREA)

Claims (12)

  1. Bilderzeugungsvorrichtung mit
    einem bilderzeugenden Element, das eine bilderzeugende Fläche (4) aufweist, die zur Bewegung in einer ersten Richtung angeordnet ist,
    Einrichtungen (14) zur Erzeugung eines elektrostatischen, latenten Bildes auf der bilderzeugenden Fläche, wobei das latente Bild Bild- und Nicht-Bild-Bereiche auf entsprechenden ersten und zweiten elektrischen Potentialen aufweist,
    Einrichtungen (22) zum Entwickeln des elektrostatischen, latenten Bildes unter Verwendung eines flüssigen Entwicklers, der geladene Tonerteilchen enthält, die auf den Bild-Bereichen abgelegt werden sollen und auf den Nicht-Bild-Bereichen nicht abgelegt werden sollen,
    Einrichtungen (30) zum Entfernen von Tonerteilchen von den Nicht-Bild-Bereichen und von überschüssiger Flüssigkeit von sowohl den Bild- als auch den Nicht-Bild-Bereichen nach dem Entwickeln des Bildes, wobei die Einrichtungen zum Entfernen enthalten
    ein Element mit einer zweiten Fläche (74), die sich im Abstand von der bilderzeugenden Fläche (4) befindet und sich in einer zur ersten Richtung entgegengesetzten Richtung bewegt,
    Einrichtungen (46) zum Übertragen des Bildes auf ein Substrat nach dem Entfernen von überschüssiger Flüssigkeit und von Tonerteilchen von den Nicht-Bild-Bereichen, dadurch gekennzeichnet, daß
    die Einrichtungen zum Entfernen Einrichtungen (70) zum Zuführen von Reinigungsflüssigkeit zu wenigstens einem Bereich des Raumes zwischen der bilderzeugenden Fläche und der zweiten Fläche aufweisen.
  2. Vorrichtung nach Anspruch 1, mit einem Element, daß eine erste Fläche (76) aufweist, die von der bilderzeugenden Fläche (4) beabstandet ist und sich in einer zur ersten Richtung entgegengesetzten Richtung bewegt, wobei die ersten und zweiten Flächen auf dritte bzw. vierte elektrische Potentiale aufgeladen sind, die sich zwischen den ersten und zweiten Potentialen befinden und voneinander abweichen.
  3. Vorrichtung nach Anspruch 2, wobei das sich bewegende bilderzeugende Element eine Trommel (2) ist, die um eine Rotationsachse rotiert, die rechtwinklig zu der ersten Richtung liegt.
  4. Vorrichtung nach Anspruch 3, wobei das Element mit der ersten Fläche (76) ein rotierender Zylinder ist, dessen Rotationsachse rechtwinklig zu der ersten Richtung liegt.
  5. Vorrichtung nach Anspruch 4, wobei der rotierende Zylinder und die rotierende Trommel parallele Achsen aufweisen und in der gleichen Richtung rotieren.
  6. Vorrichtung nach einem der vorhergehenden Ansprüche, wobei das Element mit der zweiten Fläche (74) ein rotierender Zylinder ist, dessen Rotationsachse rechtwinklig zu der ersten Richtung liegt.
  7. Vorrichtung nach einem der Ansprüche 3 bis 5, wobei das Element mit der zweiten Fläche (74) ein zweiter rotierender Zylinder ist, dessen Achse parallel zu der Achse der Trommel (2) liegt, und wobei der rotierende Zylinder und die rotierende Trommel in der gleichen Richtung rotieren.
  8. Vorrichtung nach Anspruch 1, wobei das sich bewegende bilderzeugende Element eine Trommel (2) ist, die um eine Rotationsachse rotiert, die rechtwinklig zu der ersten Richtung liegt.
  9. Vorrichtung nach Anspruch 8, wobei das Element mit der ersten Fläche (76) ein rotierender Zylinder ist, dessen Rotationsachse rechtwinklig zu der ersten Richtung liegt.
  10. Vorrichtung nach Anspruch 9, wobei der rotierende Zylinder und die rotierende Trommel parallele Achsen aufweisen und in der gleichen Richtung rotieren.
  11. Vorrichtung nach Anspruch 6 oder 7, wobei die Zuführeinrichtungen enthalten:
    eine Flüssigkeit beinhaltendes Gehäuse, das dem rotierenden Zylinder zugeordnet ist, der die zweite Fläche aufweist, und
    Einrichtungen zum Zirkulieren der Reinigungsflüssigkeit innerhalb des Gehäuses.
  12. Vorrichtung nach einem der vorhergehenden Ansprüche, wobei die Zuführeinrichtungen Einrichtungen (31) zum Entfernen der pigmentierten Teilchen aus der Reinigungsflüssigkeit aufweisen.
EP89906820A 1988-06-06 1989-06-05 Doppelfarbbildverfahren und vorrichtung Expired - Lifetime EP0423158B1 (de)

Applications Claiming Priority (15)

Application Number Priority Date Filing Date Title
US20255188A 1988-06-06 1988-06-06
US20256988A 1988-06-06 1988-06-06
US07/202,677 US4966824A (en) 1988-06-06 1988-06-06 Liquid toner composition containing two different charge directors
US202569 1988-06-06
US202688 1988-06-06
US07/202,514 US5121164A (en) 1988-06-06 1988-06-06 Method for maintaining a liquid composition
US07/202,322 US4947201A (en) 1988-06-06 1988-06-06 Imaging system
US202514 1988-06-06
US202551 1988-06-06
US202322 1988-06-06
US07/202,688 US5108866A (en) 1988-06-06 1988-06-06 Process for preparing liquid toner composition
US202677 1988-06-06
US268855 1988-11-08
US07/268,855 US5012300A (en) 1988-06-06 1988-11-08 Two-color imaging system and process
PCT/NL1989/000042 WO1989012257A2 (en) 1988-06-06 1989-06-05 Dual color imaging method and apparatus

Publications (2)

Publication Number Publication Date
EP0423158A1 EP0423158A1 (de) 1991-04-24
EP0423158B1 true EP0423158B1 (de) 1996-05-01

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JP (1) JP2866689B2 (de)
DE (1) DE68926393T2 (de)
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JP6003916B2 (ja) * 2014-02-03 2016-10-05 コニカミノルタ株式会社 液体現像剤

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Also Published As

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DE68926393T2 (de) 1996-11-21
JP2866689B2 (ja) 1999-03-08
JPH04501616A (ja) 1992-03-19
WO1989012257A3 (en) 1990-05-17
EP0423158A1 (de) 1991-04-24
WO1989012257A2 (en) 1989-12-14
DE68926393D1 (de) 1996-06-05
HK152396A (en) 1996-08-16

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