US3576623A - Development system employing a coronode immersed in a liquid developer - Google Patents

Development system employing a coronode immersed in a liquid developer Download PDF

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Publication number
US3576623A
US3576623A US707574A US3576623DA US3576623A US 3576623 A US3576623 A US 3576623A US 707574 A US707574 A US 707574A US 3576623D A US3576623D A US 3576623DA US 3576623 A US3576623 A US 3576623A
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United States
Prior art keywords
image
developer
development
liquid
liquid developer
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Expired - Lifetime
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US707574A
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English (en)
Inventor
Christopher Snelling
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Xerox Corp
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Xerox Corp
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/06—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
    • G03G15/101—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer for wetting the recording material
    • G03G15/102—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer for wetting the recording material for differentially wetting the recording material
    • 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
    • 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

  • This invention relates to an imaging system and, more specifically, to an improved development system for electrostatic latent images.
  • electrostatic latent images may be formed and developed on the surface of certain high resistant materials, and subsequently converted into a visible image.
  • an electrostatic pattern may be formed on an insulating substrate such as by exposure to a potential source through a stencil.
  • a uniform charge is deposited on the particular surface and then dissipated by selective exposure to a pattern of activating electromag netic radiation.
  • the resulting charge pattern is conventionally made visible by development with electroscopic marking particles through electrostatic attraction thus forming a visible image or image body of electroscopic matter corresponding to the latent image. This image may then be fixed in place or transferred to a secondary surface to form the final print.
  • the developer comprises a [finely divided opaque solid dispersed in a liquid having a high electrical resistance.
  • liquid development approach has certain distinct advantages over the use of dry development techniques, such as greater simplicity and increased speed of operation coupled with improved control and versatility in the development process there are inherent disadvantages in such a system. While increasing the speed of development and therefore the speed of the entire printing process, the liquid development approach still provides a process wherein there is no apparent technique whereby the amount of developer which contacts the surface of the image bearing member may be effectively controlled. Furthermore, it is generally necessary to introduce an additional mechanism into the system to provide for a uniform developer medium in the development zone.
  • Another object of this invention is to provide a novel liquid development process capable of localized control at the site of image development.
  • Another object of this invention is to provide a liquid development system 'which insures increased speed of development while simultaneously replenishing the depleted developer in the development zone.
  • a further object of this invention is to provide a novel liquid development imaging system which applies nonuniform electric -field phenomena in a liquid developer process.
  • Still a further object of this invention is to provide a liquid development system which is capable of regulating image density.
  • the foregoing objects and others are accomplished in accordance with the present invention, generally speaking, by providing a development process whereby an electrostatic charge pattern is formed on the surface of a high resistance material.
  • the resulting pattern is brought into close association with a liquid developer.
  • Present beneath the surface of the liquid developer is positioned at least one coronode unit capable of emitting charge to the surrounding liquid environment.
  • the development system consists of a point source-to-plane imaging system.
  • the developer liquid may be presented to the surface of the image bearing member in the form of a liquid spray by electrostatic atomization continuously generated and simultaneously charged by the coronode unit immersed in the developer.
  • the process of the present invention to a polychromatic imaging system, utilizing the proper filter systems it is possible to produce a multicolor print in a stepwise mode by selective displacement of a liquid developer contain ing the proper colorant in a manner 'which eliminates conventional registration problems.
  • the presence of a coronode beneath the surface of a liquid developer increases the development speed by insuring that pigment or toner depleted during the development process is quickly replaced by fresh developer. This results from the pumping action caused by the discharge of the coronode (electrode) in the liquid.
  • the system comprises a point-to-plane electrode arrangement.
  • the development zone may be localized and development action controlled externally by this means of deforming the liquid surface thus providing a technique of regulating image density.
  • the process of the present invention also insures homogeneous particle charge polarity.
  • the charging of the suspended pigmented or toner particles by eiher charge transfer from the ionized liquid or direct contact with the coronode allows for the use of not only those developer materials which heretonow have been found suitable in a liquid development process, but also permits the use of normally unsuitable developer material.
  • point source is used in the course of the present invention it is intended to mean a localized source of energy such as a needle, wire, thin knife-like edge or other similar device.
  • FIG. 1 represents a continuous imaging and development process of the present invention utilizing a dielectric drum as the image support member.
  • FIG. 2 represents a continuous imaging and development process of the present invention utilizing a photoconductive drum as the image support member.
  • FIG. 1 there is seen a rotary drum 1 which for the sake of the present illustration will be represented as a dielectric material such as Mylar, polyethylene terephthalate, commercially available from E. I. du Pont de Nemours & Co.
  • an electrostatic charge pattern 3 representing the image which is to be reproduced, formed at exposure station 4.
  • a trough like container 5 Positioned beneath the drum or imaging substrate 1 is a trough like container 5 which carries a developing liquid 6 consisting of a dispersion of a color supplying component in a neutral organic liquid with high electrical resistivity and low dielectric constant. Immersed in the insulating liquid developer in .an electrode 7.
  • a high voltage source 10 connects the immersed electrode 7 to ground.
  • the surface of the insulating liquid developer may be deformed selectively so as to contact the surface of the image bearing drum when the latent image 3 passes above the surface of the liquid developer thus regulating the size of the developer zone which contacts the latent image.
  • the amount of developer to which the latent image is exposed has a bearing upon the density of the respective images and prints produced therefrom.
  • the resulting developed image will then continue to rotate with the drum to transfer station 11 where it contacts transfer web 12 to which it is transferred upon pressure applied by the transfer roller 13.
  • the web is fed and rewound by idler rollers 14 and 15, respectively.
  • the image is fixed by heating unit 16.
  • the surface of the rotating drum is then cleaned of its residual developer by brush 17 and is thus prepared for a new imaging cycle.
  • FIG. 2 represents an application of the process of the present invention utilizing a photoconductive drum as the imaging member.
  • a photoconductivc drum generally designated 20 which consists of a conductive substrate 21 and a thin photoconductive layer 22 overlying the surface.
  • the photoconductive cylinder rotates in the direction indicated by the arrow so as to pass charging device 23 which produces a uniform charge on the surface of the photoconductive layer.
  • the charged surface then passes under exposure station 24 producing an electrostatic charge pattern 25 on the surface of the photoconductive layer 22.
  • the latent image continues around the drum until it reaches the development station which consists of a container 26 for the high resistance liquid developer 27. Immersed in the liquid developer is electrode 28, a substantial portion of which is covered with dielectric material 29.
  • a high voltage source 30 connects the immersed electrode to ground. As the latent image passes above the surface of the immersed electrode, a potential is applied to voltage source 30 which causes the surface of the liquid developer to be deformed so as to selectively contact the electrostatic charge pattern on the surface of the image bearing member.
  • This controlled development process permits the development of an image pattern having a specific density.
  • the developed image then proceeds to transfer station generally designated 31 consisting of the transfer roller 32 and feed and take up rollers 33 and 34, respectively.
  • the developed image is pressure transferred to the surface of a copy Web 35 and fixed, by any suitable means, such as a heat generating unit 36.
  • the drum surface then passes the brush mechanism 37 which cleans the residual developer material from the surface of the photoconductive layer. The drum is then ready for recycling.
  • the immersed electrode of the present invention is represented in the illustrations as an electrode with a knife-like edge from which the charges are emitted, any suitable configuration may be employed which will achieve the desired effect.
  • a series of needle-like electrodes may be employed to provide the necessary field and current density or a thin wire electrode may be used such as a corotron wire.
  • a corotron wire it is generally desirable to utilize an insulated shield to partially enclose the corotron wire so as to direct the charge to the desired area of the liquid developer while preventing unnecessary loss of energy.
  • a Wide range of voltages may be employed in the present system.
  • the applied potential will depend upon the desired image density, thus controlling the degree of image developer contact with the image-bearing support.
  • the applied potential necessary to attain the desired effect will vary depending upon the spacing of the electrode with respect to the liquid developer surface, as well as the spacing of the surface of the liquid developer with respect to the image support member and the shape of the immersed electrode.
  • the emitting surface of the immersed electrode will be positioned about 1 to about 10 mm. below the surface of the liquid developer and the image support member -will be operated at a distance of about .5 to about 5 mm. from the surface of the liquid developer.
  • the applied potential generally will range from about 5 kv. to about 10 kv.
  • Any suitable organic liquid having a high volume resistivity, preferably at least about 10 ohms-cm. or greater and a low dielectric constant preferably less than about 3.4, may be used in the course of the present invention.
  • Typical liquids include aromatic hydrocarbons such as benzene, toluene, xylene, etc.; aliphatic hydrocarbons such as hexane, cyclohexane, heptane, etc.; halogenated hydrocarbons such as trichloroethylene or carbon tetrachloride; silicone oils and mixtures thereof.
  • Any suitable colorant particle which may be suspended in the insulating liquid may be utilized.
  • Typical particles are talcum powder, charcoal, aluminum bronze, sulfur, pulverized resins of all varieties such as ordinary rosin, sealing wax, coumarone-indene resin, the treated pine resins sold under the trademark Vinsol resin, and various other synthetic and natural resins. Hard waxes are also found suitable. Powdered dyes may also be used or the resin or other powder used may be dyed any color desired. For example, the Vinsol resin may be melted with a small proportion of nigrosene dye, cooled and pulverized to give a dark colored powder. The suspended colorant or toner particles are electrostatically charged and develop a latent image by migration to the image surface under infiuence of the image charge.
  • the specific image support member utilized will be determined by the particular process employed to form the electrostatic charge pattern. If the electrostatic charge pattern is to be formed at'a remote station and then transferred to the support member or formed directly on the support member by selective charge deposition, then generally any suitable insulating material may be used as the particular support. Typical dielectric materials include polyethylene, polyurethane, polyethylene terephthalate, polyvinyl chloride, polytetrafluoroethylene and polyvinyl fluoride.
  • a photoreceptor consisting of a base conductive support such as aluminum or steel will have coated on its surface a photoconductive layer in either a homogeneous form such as a selenium coating or in a suspension form of a photoconductive pigment in a carrier resin.
  • Typical photoconductive compositions and plates are those as disclosed in U.S. Pat. No. 3,121,006; 3,121,007; and 3,151,982.
  • the image may be then transferred to a secondary substrate or copy web by any suitable technique such as by pressure transfer or adhesive pickofl.
  • Typical materials that may be used as a copy web support include polyethylene terephthalate, polyvinyl fluoride, polyurethane, polyethylene, and ordinary bond paper. Any suitable means may be used to fix the image formed on the copy web such as by placing a lamination over the top surface of the transferred pigment image or by heat or vapor fusing of the resulting image to the substrate.
  • Example I 15 grams of a phenol modified pentaerythritol ester of rosin known under the tradename as Pentarol 20 is digested in 25 grams of xylene and when solution is completed, 15 grams of a linseed oil modified alkyd resin of medium oil length, known under the tradename Rhodene L6/100 is added. 150 grams of Phthalocyanine Blue is then added to the above mix and blended in a ball mill until mixing is complete and pigment particle size is reduced to about 0.5 micron, average. After about 8 hours of milling in the ball mill it is found that the pigment particles are coated with a thin film of the above mix.
  • the resulting paste is dispersed in a chlorinated-fiuorinated hydrocarbon solvent, trichloromonofluoromethane, forming the developer liquid, approximately 0.5 gram of the mix being dispersed in 100 ml. of the liquid.
  • a coronode with a knife-like edge is immersed in the liquid developer which is contained in a trough-like arrangement.
  • An electrostatic latent image formed on the surface of a zinc oxide plate is placed in a position about 2 mm. from the surface of the liquid developer.
  • the immersed electrode has its discharge edge from which the corona is emitted situated about 5 mm. beneath the surface of the liquid developer opposite the imaged photoconductive plate.
  • a voltage of about 7 kv. is applied to the immersed coronode.
  • the surface of the liquid developer is selectively displaced by the applied voltage and contacts the surface of the imaged zinc oxide photoconductive substrate.
  • the coated pigment particles Upon contact of the liquid developer with the imaged plate the coated pigment particles deposit on those areas of the image where a suitablpotential exists, until the charge of the image has been satisfied by the particles deposited, the particles being held in position by the electrical force until the carrier liquid present on the imaged substrate evaporates. A high density image is thus developed on the photoconductive plate.
  • Example II The following blend is prepared:
  • Example III The following developer paste is formulated:
  • the Pentarol 20 is digested in xylene and when solution is complete the Rhodene L6/100 is added.
  • the Phthalocyanine Blue is then mixed with the resins and blended in a ball mill until mixture is complete and pigment particle size is reduced to the required fineness of about 0.5 micron, average.
  • the resulting blend is mixed in a ball mill for about 8 hours.
  • About 0.5 g. of the developer paste is mixed in about 100 cos. of trichloroethylene.
  • a Mylar substrate having an electrostatic latent image formed thereon is placed about 2 mm. above the surface of the liquid developer.
  • a knife-like, longitudinally shaped coronode is immersed beneath the surface of the liquid developer opposite the latent image with the knife-like coronaemitting edge being about 5 mm. beneath the surface of the liquid developer.
  • the excess solvent evaporates from the surface of the Mylar substrate, thus leaving a high density image developed on the surface of the Mylar substrate.
  • Example IV The process of Example I is repeated with the exception that the coronode is located about 1 mm. beneath the surface of the developer solution.
  • the developer solution is thus presented to the latent image in the form of a spray which develops the image in a manner similar to that disclosed in Example I. A high density image is produced.
  • any of the above listed typical materials may be substituted when suitable in the above examples With similar results.
  • steps used to carry out the process of the present invention other steps or modifications may be used, if desirable.
  • multiple development stations may be used in the development process.
  • other materials may be incorporated in the imaging suspension, the immersed coronode, or the particular image support to enhance, synergize, or otherwise desirably affect the properties of the process of the present invention.
  • the developer liquid may contain thickening agents so as to effectively control the viscosity of the developer solution.
  • a process of image development comprising forming an electrostatic latent image on the surface of an image support member, positioning said image bearing member in close proximity to the surface of a liquid developer suspension, said suspension comprising developer particles dispersed in an insulating carrier liquid, said developer having immersed beneath the surface at least one coronode 8 capable of emitting charge to the surrounding liquid References Cited environment, and applying a potential to said immersed UNITED STATES PATENTS coronode of such a magnitude to selectivity deform the surface of said liquid developer in a controlled manner so 3,084,043 4/ 1963 Gundlach 96 1 as to contact the latent image on said support member, thereby developing said image.
  • 5 GEORGE F. LESM-ES Primary Examiner 2.
  • said image support member comprises an insulating substrate having a latent image electrostatically formed thereon.
  • U S C1 X 3 The process as disclosed in claim 2 wherein said insulating substrate is a photoreceptor. 118637; 1l737LX; 252-62.1

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Wet Developing In Electrophotography (AREA)
  • Liquid Developers In Electrophotography (AREA)
  • Photoreceptors In Electrophotography (AREA)
US707574A 1968-02-23 1968-02-23 Development system employing a coronode immersed in a liquid developer Expired - Lifetime US3576623A (en)

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Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3722994A (en) * 1969-06-04 1973-03-27 Canon Kk Method and device for removing developing liquid
US3782818A (en) * 1972-11-17 1974-01-01 Savin Business Machines Corp System for reducing background developer deposition in an electrostatic copier
US3839071A (en) * 1969-12-29 1974-10-01 Honeywell Inc Printing method
JPS49114425A (de) * 1973-02-28 1974-10-31
US3918966A (en) * 1972-09-28 1975-11-11 Commw Of Australia Liquid development of an electrical image in which a pulsating field is employed
US3933490A (en) * 1971-11-04 1976-01-20 Canon Kabushiki Kaisha Improvements in transfer electrophotography
US3972611A (en) * 1970-03-18 1976-08-03 Canon Kabushiki Kaisha Apparatus for transferring images produced by liquid developer
JPS52152238A (en) * 1977-06-20 1977-12-17 Canon Inc Liquid developing device
US4126711A (en) * 1974-09-24 1978-11-21 Xerox Corporation Charge pattern development method and apparatus
US4139299A (en) * 1975-04-04 1979-02-13 Ricoh Company, Ltd. Auto-bias developing apparatus
US4146324A (en) * 1971-07-08 1979-03-27 Canon Kabushiki Kaisha Liquid developing device in electrophotographic copying apparatus
USRE31964E (en) * 1974-06-17 1985-08-06 Savin Corporation Automatic development electrode bias control system
US4707112A (en) * 1986-05-16 1987-11-17 Xerox Corporation Liquid development system
DE4118434A1 (de) * 1990-06-06 1991-12-12 Mitsubishi Paper Mills Ltd Verfahren zur elektrophotographischen umkehr-nassentwicklung
US5122815A (en) * 1989-11-30 1992-06-16 Seikosha Co., Ltd. Magnetic recording device
US5128721A (en) * 1988-02-12 1992-07-07 Nec Corporation Liquid development apparatus for developing a latent electrostatic image
EP0638850A2 (de) * 1993-08-09 1995-02-15 Lexmark International, Inc. Elektrophotographisches Bilderzeugungsgerät
US20150048709A1 (en) * 2012-03-21 2015-02-19 Tm4 Inc. Interphase Insulator

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3722994A (en) * 1969-06-04 1973-03-27 Canon Kk Method and device for removing developing liquid
US3839071A (en) * 1969-12-29 1974-10-01 Honeywell Inc Printing method
US3972611A (en) * 1970-03-18 1976-08-03 Canon Kabushiki Kaisha Apparatus for transferring images produced by liquid developer
US4146324A (en) * 1971-07-08 1979-03-27 Canon Kabushiki Kaisha Liquid developing device in electrophotographic copying apparatus
US3933490A (en) * 1971-11-04 1976-01-20 Canon Kabushiki Kaisha Improvements in transfer electrophotography
US3918966A (en) * 1972-09-28 1975-11-11 Commw Of Australia Liquid development of an electrical image in which a pulsating field is employed
US3782818A (en) * 1972-11-17 1974-01-01 Savin Business Machines Corp System for reducing background developer deposition in an electrostatic copier
JPS49114425A (de) * 1973-02-28 1974-10-31
USRE31964E (en) * 1974-06-17 1985-08-06 Savin Corporation Automatic development electrode bias control system
US4126711A (en) * 1974-09-24 1978-11-21 Xerox Corporation Charge pattern development method and apparatus
US4139299A (en) * 1975-04-04 1979-02-13 Ricoh Company, Ltd. Auto-bias developing apparatus
JPS52152238A (en) * 1977-06-20 1977-12-17 Canon Inc Liquid developing device
US4707112A (en) * 1986-05-16 1987-11-17 Xerox Corporation Liquid development system
US5128721A (en) * 1988-02-12 1992-07-07 Nec Corporation Liquid development apparatus for developing a latent electrostatic image
US5122815A (en) * 1989-11-30 1992-06-16 Seikosha Co., Ltd. Magnetic recording device
DE4118434A1 (de) * 1990-06-06 1991-12-12 Mitsubishi Paper Mills Ltd Verfahren zur elektrophotographischen umkehr-nassentwicklung
US5398105A (en) * 1990-06-06 1995-03-14 Mitsubishi Paper Mills Limited Method of electrophotographic wet reversal development
EP0638850A2 (de) * 1993-08-09 1995-02-15 Lexmark International, Inc. Elektrophotographisches Bilderzeugungsgerät
EP0638850A3 (de) * 1993-08-09 1995-03-08 Lexmark International, Inc. Elektrophotographisches Bilderzeugungsgerät
US20150048709A1 (en) * 2012-03-21 2015-02-19 Tm4 Inc. Interphase Insulator
US9647504B2 (en) * 2012-03-21 2017-05-09 Tm4 Inc. Interphase insulator

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Publication number Publication date
DE1908292B2 (de) 1974-04-25
DE1908292C3 (de) 1974-11-21
GB1259880A (en) 1972-01-12
DE1908292A1 (de) 1969-09-11

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