US3707389A - Latent electrostatic image development - Google Patents

Latent electrostatic image development Download PDF

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Publication number
US3707389A
US3707389A US104365A US3707389DA US3707389A US 3707389 A US3707389 A US 3707389A US 104365 A US104365 A US 104365A US 3707389D A US3707389D A US 3707389DA US 3707389 A US3707389 A US 3707389A
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US
United States
Prior art keywords
toner
donor
development
reservoir
donor member
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Expired - Lifetime
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US104365A
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English (en)
Inventor
John Maksymiak
James W Smith
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Xerox Corp
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Xerox Corp
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Publication date
Application filed by Xerox Corp filed Critical Xerox Corp
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Publication of US3707389A publication Critical patent/US3707389A/en
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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
    • G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
    • G03G15/0806—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer on a donor element, e.g. belt, roller
    • G03G15/0808—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer on a donor element, e.g. belt, roller characterised by the developer supplying means, e.g. structure of developer supply roller

Definitions

  • the reservoir is maintained at a potential lower than the charged donor member.
  • the toner is triboelectrically charged in the vibrating reservoir via a coating on the inside of the reservoir capable of so charging the toner and said toner is attracted to the dielectric surface of the donor which is corona charged oppositely to that of the toner.
  • This method and apparatus relates to the development of electrostatic images and more particularly to an improved method and apparatus for xerographic development by which a toner layer is presented to a latent image for development thereof.
  • a photoconductive surface is charged and then exposed to a light pattern of the information to be reproduced thereby forming an electrostatic latent image on the photoconductive surface.
  • Toner particles which may be finely divided, pigmented, resinous material are presented to the latent image Where they are attracted to the photoconductive surface.
  • a toner image can be fixed and made permanent on the photoconductive surface or it can be transferred to another surface where it is fixed.
  • Transfer development broadly involves bringing a layer of toner to an imaged photoconductor where toner particles will be transferred from the layer to the image areas.
  • a layer of toner particles is applied to a donor member which is capable of retaining the particles on its surface and then the donor member is brought into close proximity to the surface of the photoconductor. In the closely spaced position, particles of toner in the toner layer on the donor member are attracted to the photoconductor by the electrostatic charge on the photoconductor so that development takes place.
  • the toner particles must traverse an air gap to reach the imaged regions of the photoconductor.
  • the toner-laden donor actually contacts the imaged photoreceptor and no air gap is involved.
  • the tonere United States Patent O 3,707,389 Patented Dec. 26, 1972 laden donor is rolled in a non-slip relationship into and out of contact with the electrostatic latent image to develop image in a single rapid step.
  • the toner-laden donor is skidded across the xerographic surface. Skidding the toner by as much as the width of the thinnest line will double the amount of toner available for development of a line which is perpendicular to the skid direction, and the amount of skidding can be increased to achieve greater density or greater area coverage.
  • transfer development is generic to development techniques where (1) the toner layer is out of contact with the image photoconductor and the toner particles must traverse an air gap to effect development, (2) the toner layer is brought into rolling contact with the image photoconductor to effect development, and (3) the toner layer is brought into contact with the imaged photoconductor and skidded across the image surface to effect development. Transfer development has also come to be known as touchdown development.
  • a cylindrical or endless donor member is rotated so that its surface can be presented to the moving surface of a photoconductive drum bearing an electrostatic image thereon.
  • a number of processing stations including, a donor loading station, at which toner is retained on the donor member surface; a charging station at which a uniform charge is placed on the particles of toner retained on the donor surface; a development station at which the toner particles are presented to the image photoconductor for image develop ment; and another charging station at which a neutralizing charge is placed upon the residual toner particles and at which a cleaning member removes residual toner from the peripheral surface of the donor.
  • the first layer of poorly insulating material is so selected as to have a resistivity sufficiently high to accept an electrostatic charge thereby permitting electrostatic charging of the entire donor surface including the posts or dots and the areas therebetween to uniform potential.
  • the resistivity of the first dielectric is sufiiciently low so that by the time the donor member has moved from the point of charging into the toner loading mechanism, substantially all of the electrostatic charge on this portion has been lost, i.e. discharged to the condutive backing. This then leaves the posts or dots uniformly charged to a desired potential by virtue of its considerably higher resistivity.
  • the toner particles When a donor member of this construction comes into contact with a suitably charged mass of toner particles, the toner particles will be attracted to the post or dot areas and the regions between the dots or posts will be free of toner particles.
  • the donor member in this manner is loaded with toner for presentation to the development region of the system.
  • Still another object of the invention is to improve upon known transfer development processes.
  • the apparatus includes a means for developing the latent image and this means includes: (a) a donor member adapted to transport toner particles to said said latent image comprising an endless member having a continuous, corona-chargeable dielectric surface; (b) means to continuously advance said donor member past a plurality of treating stations, said treating stations including: (1) a charging station located adjacent the surface of said donor member and including a charging means adapted to corona charge the surface of said donor member; (2) a toner loading station including a toner support member and a supply of toner particles supported thereby, said support member comprising a conductive material having on the toner-contacting surface thereof a material capable of triboelectrically charging said toner particles to a polarity opposite to that of the charge on the surface of said donor member; means for maintaining said conductive material at a lower potential than the charge on said donor member, said toner support member being located
  • the present invention is also directed to a method of developing a latent electrostatic image.
  • the process includes forming a latent electrostatic image on the surface of an image-retaining surface, transporting the surface of a donor member, having a corona-chargeable dielectric surface, past a plurality of treating stations, said treating stations including, (1) a toner loading station comprising a supply of toner particles supported by a conductive support member which has on the toner-contacting surface thereof a material capable of triboelectrically charging said toner particles during relative motion therebetween, (2) a charging station including a charging means adapted to corona charge said dielectric surface; (3) a development station at which toner particles carried by said donor member are presented in developing relation to said latent image; maintaining said support member in close proximity to the periphery of said donor member; corona charging the surface of said donor member while vibrating said conductive support member so as to charge said toner particles and fiuidize the same into contact with said dielectric surface and while maintaining said conductive support member at
  • FIG. 1 is a sectional view of xerographic apparatus in accordance with the present invention.
  • FIG. 2 is an enlarged cross sectional view of one portion of the donor member and toner loading station in accordance with the present invention.
  • the present invention is a transfer development sys tem and method in which toner particles are applied to an electrostatic latent image on a latent electrostatic image retaining surface to develop the image.
  • the system and method is described herein as part of a xerographic copier, it can be utilized in conjunction with any reproduction system wherein a latent electrostatic image is to be developed by applying toner thereto.
  • a xerographic plate is in the form of a drum 10 which passes through stations A-E in the direction shown by the arrow.
  • the drum has a suitable photosensitive surface, such as one including selenium overlying a layer of conductive material, on which a latent electrostatic image can be formed.
  • the various stations about the periphery of the drum which participate in the reproduction process are: charging station A, exposing station B, developing station C, transfer station D, and cleaning station E.
  • Stations A, B, D, E represent more or less conventional means for carrying out their respective functions. Apart from their association with the novel arrangement to be described with respect to station C they form no part of the present invention.
  • a suitable charging means 12 e.g. a corotron, places a uniform electrostatic charge on the photoconductive material.
  • a light pattern via a suitable exposing apparatus 14, e.g. a projector, is exposed onto the charged surface of drum 10.
  • the latent image thereby formed on the surface of the drum is developed or made visibly by the application of a finely divided pigmented resinous powder called toner, at developing station C, which is described in greater detail below.
  • transfer station D comprising copy sheet 16, corona charging device 18 and fuser device 20.
  • cleaning station E comprising cleaning device 22, e.g. a rotating brush.
  • the apparatus includes a donor member 24.
  • Donor member 24 includes a grounded metal cylinder 26 carrying on the surface thereof a corona chargeable dielectric film 28-.
  • the donor member is rotatably mounted adjacent a toner reservoir 32 which is more particularly described below.
  • Reservoir 32 contains a supply of toner particles 34.
  • the donor roll 2 f is located so as to provide a small gap between the surface of drum 10 and the outer surface of a toner layer carried by donor roll 24. This gap can be approximately l-10 mils.
  • Donor roll 24 is adapted to be rotated in the direction shown by the arrow.
  • a charging means 30 e.g. a corona charging device.
  • This charging device is located between the toner reservoir 32 and the development region of the system and is adapted to corona charge the surface of donor roll 24 prior to its entry into the toner reservoir.
  • a second charging device 38 eg, a corona charging device, which is adapted to impart a uniform charge to toner particles carried by the surface of the donor roll.
  • the donor roll is prepared for toner reloading by exposing the residual toner thereon to a neutralizing charging means 40, e.g. a corotron, to make easier the removal of the residual toner by way of a suitable cleaning means, e.g. a rotating brush 42, which may be equipped with a vacuum means not shown.
  • a neutralizing charging means 40 e.g. a corotron
  • a suitable cleaning means e.g. a rotating brush 42, which may be equipped with a vacuum means not shown.
  • the donor roll is thus freed of any image history or ghost image from the development region and is prepared to pick up a new supply of toner.
  • Toner reservoir 32 includes a conductive support member 44 having on the interior toner-contacting surface thereof material 46 which is capable of triboelectrically charging the toner particles to a polarity opposite to that of the charge on the surface of the donor member.
  • the material selected as coating 46 should be such that when relative motion is created between this surface and toner particles supported thereby, a positive charge will be produced on the one material and a negative charge on the other.
  • An example of such a material is polymerized methyl methacrylate known commercially as Lucite and manufactured by E. I. du Pont de Nemours & Company, Wilmington, Del.
  • This material when in frictional contact with a toner material such as carbon-pigmented, resinmodified phenolformaldehyde resin known commercially as Amberol F-71, manufactured by Rohm and Haas Company, the Resinous Products Division, Washington Square, Philadelphia, Pa., causes the toner to acquire a negative charge while it acquires a positive charge.
  • a toner material such as carbon-pigmented, resinmodified phenolformaldehyde resin known commercially as Amberol F-71, manufactured by Rohm and Haas Company, the Resinous Products Division, Washington Square, Philadelphia, Pa.
  • a toner material such as carbon-pigmented, resinmodified phenolformaldehyde resin known commercially as Amberol F-71, manufactured by Rohm and Haas Company, the Resinous Products Division, Washington Square, Philadelphia, Pa.
  • Other suitable materials to be employed as coating 46 and as the toner particles herein are represented by those disclosed in US. Pat. 2,638,416.
  • Conductive support member 44 is shown to
  • a vibrating means 36 is in association with toner reservoir 32 and is adapted to impart relative motion between the material 46 coated on the inside reservoir 32 and the toner particles.
  • the degree of relative motion should be such that it will cause rubbing contact of the toner particles with material 46 and also to bring the toner particles into contact with the surface of donor member 24.
  • Charging device 30 is shown depositing a positive charge onto the surface of dielectric layer 28. As the donor member rotates into the toner particles, the particles are attracted to the positively corona charged dielectric donor surface.
  • the toner reservoir is filled with an appropriate toner and the reservoir is vibrated via vibrating means 36.
  • Next donor member 24 is rotated and a corona charge is applied to the surface thereof via charging means 30.
  • the charged donor surface as it reaches its lowest point in the reservoir, will attract toner particles to the surface thereof and these toner particles will be transported to the development region for development of the latent electrostatic image.
  • charging device 38 e.g. a corona charging device, can apply a uniform charge to the layer of toner.
  • the donor member has been described basically as a cylinder, it may be an endless belt adapted to deliver toner from the toner source to the several stations.
  • Conventional drive means e.g. motors, belts, etc. are employed to drive the several movable members all in a manner well within the skill of the art.
  • the method of developing a latent electrostatic image comprising forming a latent electrostatic image on the surface of an image-retaining surface, transporting an endless donor member, having a corona-chargeable dielectric surface on a conductive substrate, past a plurality of treating stations, said treating stations including, (1) a toner loading station comprising a toner support member and a supply of toner particles supported thereby, said support member being of a conductive material which has on the toner-contacting surface thereof a material capable of triboelectrically charging said toner particles during relative motion therebetween; (2) a charging station including a charging means adapted to corona charge said dielectric surface prior to its contact with toner particles; and (3) a development station at which toner particles carried by said donor member are presented in developing relation to said latent image; maintaining said toner support member in close proximity to the periphery of said donor member; maintaining said conductive substrate at a reference potential and uniformly corona charging the surface of said donor member while vibrating said conductive support member, so as to charge

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Dry Development In Electrophotography (AREA)
  • Electrophotography Using Other Than Carlson'S Method (AREA)
US104365A 1971-01-06 1971-01-06 Latent electrostatic image development Expired - Lifetime US3707389A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US10436571A 1971-01-06 1971-01-06

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US3707389A true US3707389A (en) 1972-12-26

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US (1) US3707389A (cs)
JP (1) JPS5432333B1 (cs)
BE (1) BE777721A (cs)
CA (1) CA949827A (cs)
DE (1) DE2200449A1 (cs)
FR (1) FR2121330A5 (cs)
GB (1) GB1375048A (cs)
IT (1) IT946354B (cs)
NL (1) NL7200006A (cs)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3866574A (en) * 1973-02-15 1975-02-18 Xerox Corp Xerographic developing apparatus
US3914460A (en) * 1973-01-09 1975-10-21 Xerox Corp Development utilizing electric fields
US3950089A (en) * 1975-02-24 1976-04-13 Xerox Corporation Coated roll for magnetic brush development and cleaning systems
US4155330A (en) * 1977-07-25 1979-05-22 Eastman Kodak Company Electrographic development apparatus for use with conductive toner
US4266503A (en) * 1978-05-25 1981-05-12 Tokyo Shibaura Denki Kabushiki Kaisha Apparatus for forming a cloud of toner particles
DE3148231A1 (de) * 1980-12-05 1982-10-14 Ricoh Co., Ltd., Tokyo Entwicklungseinrichtung
US5229823A (en) * 1992-01-30 1993-07-20 Eastman Kodak Company Toner agitator system
US5742885A (en) * 1996-06-24 1998-04-21 Xerox Corporation Development system employing acoustic toner fluidization for donor roll

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4618241A (en) * 1981-07-27 1986-10-21 Xerox Corporation Apparatus, process for charging toner particles

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3914460A (en) * 1973-01-09 1975-10-21 Xerox Corp Development utilizing electric fields
US3866574A (en) * 1973-02-15 1975-02-18 Xerox Corp Xerographic developing apparatus
US3950089A (en) * 1975-02-24 1976-04-13 Xerox Corporation Coated roll for magnetic brush development and cleaning systems
US4155330A (en) * 1977-07-25 1979-05-22 Eastman Kodak Company Electrographic development apparatus for use with conductive toner
US4266503A (en) * 1978-05-25 1981-05-12 Tokyo Shibaura Denki Kabushiki Kaisha Apparatus for forming a cloud of toner particles
DE3148231A1 (de) * 1980-12-05 1982-10-14 Ricoh Co., Ltd., Tokyo Entwicklungseinrichtung
US5229823A (en) * 1992-01-30 1993-07-20 Eastman Kodak Company Toner agitator system
US5742885A (en) * 1996-06-24 1998-04-21 Xerox Corporation Development system employing acoustic toner fluidization for donor roll

Also Published As

Publication number Publication date
AU3768972A (en) 1973-07-12
FR2121330A5 (cs) 1972-08-18
BE777721A (fr) 1972-07-05
JPS5432333B1 (cs) 1979-10-13
CA949827A (en) 1974-06-25
GB1375048A (cs) 1974-11-27
NL7200006A (cs) 1972-07-10
DE2200449A1 (de) 1972-07-20
IT946354B (it) 1973-05-21

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