US3468693A - Method and apparatus for liquid development of electrostatic images by immersion - Google Patents

Method and apparatus for liquid development of electrostatic images by immersion Download PDF

Info

Publication number
US3468693A
US3468693A US539783A US3468693DA US3468693A US 3468693 A US3468693 A US 3468693A US 539783 A US539783 A US 539783A US 3468693D A US3468693D A US 3468693DA US 3468693 A US3468693 A US 3468693A
Authority
US
United States
Prior art keywords
liquid
toner
carrier
tank
developer
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
Application number
US539783A
Other languages
English (en)
Inventor
Walter J Hanson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pitney Bowes Inc
Original Assignee
Pitney Bowes Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Pitney Bowes Inc filed Critical Pitney Bowes Inc
Application granted granted Critical
Publication of US3468693A publication Critical patent/US3468693A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • G03G15/108—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer with which the recording material is brought in contact, e.g. immersion or surface immersion development
    • 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
    • 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
    • G03G15/11—Removing excess liquid developer, e.g. by heat

Definitions

  • This invention relates to an improved developing method and apparatus. It more particularly relates to an improvement in the application of liquid developer and in the toner tank structure of electrophotographic copying machines using photoconductive materials.
  • Copying machines known generally as electrostatic are well known for making copies of original documents.
  • a uniform electrostatic charge is placed on a photoconductive coating on a carrier on which the copy is to be reproduced.
  • the electrostatic charge may be put on the coating by any suitable manner well known in the art such as by means of a corona discharge unit.
  • After the coating has been charged it is exposed to a light pattern corresponding to the image of the original document to be produced.
  • the electrostatic charge flows from the areas struck by light leaving a latent electrostatic image in the areas which are not struck by light and still retain the charge.
  • suitable charged toner particles are applied to the surface which adhere in the image area to form a copy image.
  • the particles adhere naturally, but they may also be fused later by application of heat.
  • the carrier which is usually a paper sheet is transported by rollers through a toner tank in such a manner that the sheet passes beneath the surface of the toner liquid as the paper moves through the tank.
  • the development time that is the time available for applying toner particles to the latent electrostatic image, is limited to the time the carrier sheet is immersed in the developing liquid. This is further dependent on space limitations within the machine, since the paper must be developed in the tank and dried afterward before leaving the machine.
  • Toner liquid developers are generally composed of a small amount of finely divided particles suspended in a clear dielectric liquid.
  • the particles may be carbon black, colored resins or dye pigments.
  • the particles must have a charge opposite in polarity to the charge placed on the copy paper.
  • a negative electrostatic charge is generally placed on the copy sheet having a photoconductive coating, e.g. zinc oxide, so that the toner particles will be required to have a positive charge.
  • the liquid carrier is a suitable dielectric liquid such as for example cyclohexane, kerosene, xylene or other suitable hydrocarbon liquids. It will be understood that any suitable liquid toners can be used with the invention.
  • the toner particles are applied as a suspension in the liquid.
  • the carrier paper after leaving the developing tank passes between a pair of rollers which continue to transport the paper away from the developing tank.
  • this pair of rollers also applies a squeegee action to the paper to remove liquid and aid in drying.
  • the liquid squeezed by the rollers runs down the surface of the carrier over the developed image, back to the tank. This liquid flowing back can form ripples and result in an undesirable swirl pattern on the developed copy.
  • Another object of my invention is to provide a method and means in an electrostatic copy machine for eliminating swirl patterns on the developed image.
  • a further object is ot provide an improved toner tank in an electrostatic copy machine.
  • the invention consists of providing a plastic plate or other suitable material extending from just below the surface of the liquid to the vicinity of the squeegee rollers and lying closely above the path of the copy paper being developed.
  • the spacing is such that a layer of developer liquid is maintained between the plastic plate and the copy paper, the layer including liquid carried up from the tank by the moving carrier, and liquid running back from the squeegee action of the rollers.
  • the liquid paper contact is extended.
  • the liquid since the liquid is maintained at a constant distance by the plate, there is no opportunity for ripples to develop and thus no swirl patterns form.
  • FIGURE 1 is a schematic cross-sectional view in elevation illustrating a toner tank embodying my invention.
  • FIGURE 2 is a perspective view of the tank in FIG- URE 1.
  • FIGURE 3 is a schematic cross-sectional view of an alternate embodiment of the inventive toner tank.
  • FIGURE 4 is a perspective view of the toner tank of FIGURE 3.
  • a tank 1 of generally rectangular shape contains a liquid toner developer up to level L.
  • Tank 1 is constructed of a suitable material as well known in the art, such as a clear plastic material.
  • a lower guide rack 2 consists of ribs 3 (see FIG. 2) attached to supports 4 and 5 which rest on the top edges of tank 1.
  • Upper rack 6 is positioned above rack 2 and consists of ribs 7, attached to transverse rod 7A and a continuous end plate 8 at the discharge end. Both racks 2 and 6 are made of suitable plastic material.
  • Racks 2 and 6 dip into the developer liquid below level L and form a path 9 having an entry at 10 and an exit at 11.
  • a pair of feed rollers 1212 are positioned above the entry 10 to convey a copy sheet 13 through path 9 and thus through the developer liquid.
  • a pair of rollers 1414 are positioned above the exit of path 9 to convey sheet 13 and further to squeeze any liquid from the sheet 13.
  • Plate 8 extends from slightly below liquid level L to just short of rollers 1414.
  • a photoconductive sheet 13 bearing a latent electrostatic image on the upper surface formed in known manner by means not shown is conveyed by rollers 1212 to the developing tank 1 and the liquid developer.
  • Sheet 13 passes into entry 10 and beneath liquid level L guided in path 9 between racks 2 and 6. While in the developer liquid, the latent electrostatic charge image attracts toner particles from the developer liquid to the sheet surface, thus developing a visible image on the photoconductive surface of sheet 13.
  • rollers 14-14 squeeze excess developer liquid from sheet 13 which runs down the upper surface of sheet 13 towards the liquid level L which could customarily cause ripples in the image.
  • Plate 8 lies closely adjacent to the moving sheet 13.
  • sheet 13 draws liquid up above the liquid level L by a meniscus action forming a continuous fluid zone F between plate 8 and sheet 13 extending from liquid level L up to rollers 14-14. Fluid zone F is also fed by liquid being squeezed by rollers 14-14 and flowing back down the surface of sheet 13. Because place 8 is in contact with fluid zone F, the fluid will always be of constant depth.
  • fluid zone F serves to extend the effective length of developer path 9 above level L.
  • backwash of depleted toner liquid serves to aid in removing toner particles which may have deposited on the nonimage areas of the paper thus eliminating background and providing a print with improved contrast.
  • FIGS. 3 and 4 show another embodiment of the invention wherein the toner tank is enclosed at the top except at the point for entry and exit of the paper.
  • the tank of FIG. 3 is basically similar to that of FIG. 1 in structure and function.
  • a cover 20 extends around the outer edges of tank 1 and below the paper path and supports the lower arcuate guide rack 2 which consists of separate ribs 3.
  • a cover 21 extends across the top of tank 1 above the paper path and is supported by cover 20 to which it is attached by suitable means such as screws, not shown.
  • the upper guide rack 22 consists of plates 23 dependent from the horizontal cover 24.
  • cover has a transverse ridge 25 and cover 21 has a series of curved tabs 26 which aid in guiding paper 13 from rollers 1212 into the entry 10 of path 9.
  • cover 24 has a transversely depressed portion 27 which dips downwardly to below the surface of liquid level L for a sufiicient distance to maintain continuous contact with level L for any minor variations in level L, then continues upwardly to form the continuous end plate 8.
  • toner tank 1 is covered except for entry 10 and exit 11 and the evaporation of toner liquid is kept to a minimum.
  • toner tank of FIG. 3 The operation and use of the toner tank of FIG. 3 is the same as that of FIG. 1.
  • An agitator or stirrer is generally provided inside tank 1 to maintain the pigment particles in suspension in the toner liquid, but this has not been illustrated for purposes of clarity. Moreover, it will be understood that level L may be maintained by any known means in the art.
  • a method for developing a latent electrostatic image on a carrier which comprises,
  • an apparatus for developing a latent electrostatic image on a carrier with a liquid toner developer comprising means for containing a body of liquid toner;
  • a tank for containing a body of said toner and having entry and exit points for the carrier;
  • said guide means includes upper and lower arcuate members spaced apart, and said plate is an extension of said upper guide members.
  • said toner tank includes a cover with entrance and exit openings, and said plate is a part of said cover adjacent said exit means.
  • An apparatus for the development of a latent electrostatic image on a carrier surface with a liquid toner developer comprising a tank for containing a body of toner;
  • said tank having a first cover means around the periphery thereof;
  • a second cover means fitted within said first cover means, entry and exit openings between said second cover means and adjacent areas of said first cover means, a lower arcuate guide means in said tank attached to said first cover means, an upper arcuate guide means attached to the lower side of said second cover means;
  • said entry and exit openings and upper and lower guide means forming a path through said tank for guiding the carrier through the body of toner;

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Wet Developing In Electrophotography (AREA)
US539783A 1966-04-04 1966-04-04 Method and apparatus for liquid development of electrostatic images by immersion Expired - Lifetime US3468693A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US53978366A 1966-04-04 1966-04-04

Publications (1)

Publication Number Publication Date
US3468693A true US3468693A (en) 1969-09-23

Family

ID=24152624

Family Applications (1)

Application Number Title Priority Date Filing Date
US539783A Expired - Lifetime US3468693A (en) 1966-04-04 1966-04-04 Method and apparatus for liquid development of electrostatic images by immersion

Country Status (6)

Country Link
US (1) US3468693A (de)
CH (1) CH453900A (de)
DE (1) DE1572355A1 (de)
FR (1) FR1517545A (de)
GB (1) GB1184839A (de)
SE (1) SE327338B (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4256398A (en) * 1978-04-12 1981-03-17 Dainippon Screen Seizo Kabushiki Kaisha Double surfaced developing tank
US4291969A (en) * 1979-10-09 1981-09-29 Raymond Gary E Photographic developer-printer assembly, and a conveying roller unit therefor
US4327456A (en) * 1979-09-13 1982-05-04 Agfa-Gevaert N.V. Apparatus for applying a processing liquid to a sheet or web material
US4367030A (en) * 1979-10-09 1983-01-04 Raymond Gary E Photographic developer-printer assembly, and a conveying roller unit therefor
US4933699A (en) * 1988-09-05 1990-06-12 Fuji Photo Film Co., Ltd. Rack for processing photosensitive material
US5032871A (en) * 1989-02-27 1991-07-16 Fuji Photo Film Co., Ltd. Guide with oblique ribs for wiping a material
US5302996A (en) * 1992-11-25 1994-04-12 Eastman Kodak Company Apparatus for processing photosensitive material

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US478282A (en) * 1892-07-05 heathfield
US1117578A (en) * 1912-04-01 1914-11-17 American Sheet & Tin Plate Feed mechanism for tinning or galvanizing machines.
US2925025A (en) * 1958-01-28 1960-02-16 Copease Corp Photocopying machine
FR1289393A (fr) * 1961-05-23 1962-03-30 Dispositif pour mettre en contact des feuilles munies d'une couche sensible avec au moins deux liquides
US3054340A (en) * 1958-12-04 1962-09-18 Zindler Lumoprint Kg Copying devices
GB914120A (en) * 1960-04-08 1962-12-28 Wilhelm Ritzerfeld Apparatus for producing printing master sheets
US3139808A (en) * 1960-04-29 1964-07-07 Ritzerfeld Wilhelm Method and apparatus for making printing form sheets
US3249088A (en) * 1963-04-03 1966-05-03 Scm Corp Developing tank unit for electrostatic printing
US3354802A (en) * 1964-07-22 1967-11-28 Savin Business Machines Corp Toner monitoring system for electrostatic copier

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US478282A (en) * 1892-07-05 heathfield
US1117578A (en) * 1912-04-01 1914-11-17 American Sheet & Tin Plate Feed mechanism for tinning or galvanizing machines.
US2925025A (en) * 1958-01-28 1960-02-16 Copease Corp Photocopying machine
US3054340A (en) * 1958-12-04 1962-09-18 Zindler Lumoprint Kg Copying devices
GB914120A (en) * 1960-04-08 1962-12-28 Wilhelm Ritzerfeld Apparatus for producing printing master sheets
US3139808A (en) * 1960-04-29 1964-07-07 Ritzerfeld Wilhelm Method and apparatus for making printing form sheets
FR1289393A (fr) * 1961-05-23 1962-03-30 Dispositif pour mettre en contact des feuilles munies d'une couche sensible avec au moins deux liquides
US3249088A (en) * 1963-04-03 1966-05-03 Scm Corp Developing tank unit for electrostatic printing
US3354802A (en) * 1964-07-22 1967-11-28 Savin Business Machines Corp Toner monitoring system for electrostatic copier

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4256398A (en) * 1978-04-12 1981-03-17 Dainippon Screen Seizo Kabushiki Kaisha Double surfaced developing tank
US4327456A (en) * 1979-09-13 1982-05-04 Agfa-Gevaert N.V. Apparatus for applying a processing liquid to a sheet or web material
US4291969A (en) * 1979-10-09 1981-09-29 Raymond Gary E Photographic developer-printer assembly, and a conveying roller unit therefor
US4367030A (en) * 1979-10-09 1983-01-04 Raymond Gary E Photographic developer-printer assembly, and a conveying roller unit therefor
US4933699A (en) * 1988-09-05 1990-06-12 Fuji Photo Film Co., Ltd. Rack for processing photosensitive material
US5032871A (en) * 1989-02-27 1991-07-16 Fuji Photo Film Co., Ltd. Guide with oblique ribs for wiping a material
US5302996A (en) * 1992-11-25 1994-04-12 Eastman Kodak Company Apparatus for processing photosensitive material

Also Published As

Publication number Publication date
CH453900A (de) 1968-03-31
DE1572355A1 (de) 1970-02-12
FR1517545A (fr) 1968-03-15
GB1184839A (en) 1970-03-18
SE327338B (de) 1970-08-17

Similar Documents

Publication Publication Date Title
US4504138A (en) Method and apparatus for developing electrostatic latent images
US3169887A (en) Electrophotographic developing apparatus
US3367791A (en) Liquid development of electrostatic images
US3276896A (en) Electrostatic printing
GB2104675A (en) Liquid developing composition for a latent electrostatic image
US3752119A (en) Liquid toner applicator
US3359945A (en) Development of electrostatic images
US3627557A (en) Liquid development by reducing the viscosity of the developer on a roller applicator prior to development
US4342823A (en) Perforate development electrode
US3468693A (en) Method and apparatus for liquid development of electrostatic images by immersion
US3783827A (en) Liquid development apparatus for electrophotography
US4259005A (en) Device and method for developing latent electrostatic images
US3672326A (en) Method and apparatus for applying liquid developer to copy sheets
US3415223A (en) Development apparatus for electrostatic copiers
US3808025A (en) Liquid developing method for electrophotography
US3682542A (en) Development of electrostatic images
US3192897A (en) Electrostatic printing apparatus
US4270485A (en) Liquid developing apparatus
US3913524A (en) Liquid developing apparatus for electrophotography
CA1150945A (en) Apparatus for developing latent electrostatic images
US3943268A (en) Liquid development process and apparatus for electrostatography
US3965861A (en) Separated roller liquid development
US3608523A (en) Trostatic toning apparatus
JP3702523B2 (ja) 液体現像剤を用いた現像装置
US4487496A (en) Device for adjusting the level of a developing mixture, which consists of a toner and carrier particles, on a developing roller