US3778144A - Xerographic development electrode apparatus - Google Patents

Xerographic development electrode apparatus Download PDF

Info

Publication number
US3778144A
US3778144A US00172839A US3778144DA US3778144A US 3778144 A US3778144 A US 3778144A US 00172839 A US00172839 A US 00172839A US 3778144D A US3778144D A US 3778144DA US 3778144 A US3778144 A US 3778144A
Authority
US
United States
Prior art keywords
development
conductive members
developer
spaced
electrode
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
US00172839A
Other languages
English (en)
Inventor
F Hudson
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.)
Xerox Corp
Original Assignee
Xerox Corp
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 Xerox Corp filed Critical Xerox Corp
Application granted granted Critical
Publication of US3778144A publication Critical patent/US3778144A/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
    • G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
    • G03G15/0801—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer for cascading

Definitions

  • This invention relates to a development electrode apparatus for developing electrostatic latent images formed on a xerographic plate such as a xerographic photoconductive .belt assembly.
  • axerographic' plate comprising a layer of photoconductive insulating material on a conductive backing is given auniform electric charge over its surface and is then exposed to the subject matter to be reproduced, uusually by conventional projection .techniques. This exposure discharges the plate areas in accordance withthe radiation'intensity that reaches them and thereby creates. an electrostatic la- 1 tent image on 'or in the photoconductive layer. Development of the.
  • latent image is effected with an electrostatically charged, finely divided material such as an electroscopic powder that is brought into surface contact with the'photoconductive layer 'and is held thereon electrostatically in a pattern corresponding to xthe electrostatic .latent image. Thereafter, the. devel-.
  • an electrostatically charged, finely divided material such as an electroscopic powder that is brought into surface contact with the'photoconductive layer 'and is held thereon electrostatically in a pattern corresponding to xthe electrostatic .latent image.
  • oped xerographic powder image is usuallytransferred to a support surface to which it may be fixed by any suitable means.
  • the two-components of the cascade developer include a relatively hardcarrier the electrostaticlatent image withsh'arpness and uniform densitypl'lowever', where'the copy to be reproduced is possessed of'images having at least some areas of other than line copy form,such as solidly wide, dark areas termed solid area," the cascade development technique is by itself known to 'be inherently unable to effect faithful development thereof. Instead of a faithful, uniform deposition acrossthe entireimage'area, there results a halo appearing development consisting of developed fringes about the image perimeter and an absence 'of'developer in the-central portions. owing to the improper and non-uniform adherence of the developer powder thereat.
  • a development electrode comprising a series of wires has been found to be ineffective which regard to the cascade development process.
  • U.S. Pat. No. 2,784,109 to Walkup a development electrode comprising a series of fine, parallel grid wires stretched out between two sides of a rigid metal frame is disclosed. While the development electrode disclosed in this patent obviates the jamming problem encountered with cascade development, the wires are spaced at such intervals that the field effect desired from the wires (i.e. the solid area enhancement) decreases.
  • a device is disclosed which comprises a plurality of flexible,
  • the development electrode apparatus as contemplated by the present invention which comprises a series of fine, parallel wires tautly stretched between two sides of a rigid rectangular structure, the wires being of a thickness and being spaced such that there is no clogging of developer during cascade development and yet retaining complete continuity in the electrode effect of the device. It has been found that the wire development electrode of the present invention is especially useful for high speed development.
  • FIG. 1 For a general understanding of the xerographic processing system in which the invention is incorporated, reference is made to FIG. 1 in which the various system components are schematically illustrated.
  • a radiation light image of a copy to be reproduced is projected onto the sensitized surface of a xerographic plate to form an electrostatic latent image thereon.
  • the latent image is usually developed with an oppositely charged developing material to form a xerographic powder image, corresponding to the latent image on the plate surface.
  • the powder image is then electrostatically transferred to a support surface to which it may be fused by any suitable form of fusing device, whereby the powder image is caused permanently to adhere to the support surface.
  • a xerographic copier having a photosensitive element 60 on which a latent electrostaticimage of the information to be reproduced is formed.
  • the photosensitive element is in the shape of a belt which is slidably mounted and driven by shafts 62.
  • the photosensitive belt comprises an electrically conductive substrate material 63 which, in turn, is covered on its other surface with a layer 64 of a photoconductive insulating material such as-vitreous selenium.
  • the photosensitive belt element has five processing stations located about its periphery which carry out the basic steps of the xerographic process. These stations include charging station 10', exposing station 20, developing station 30, transfer station 40, and cleaning station 50.
  • the latent electrostatic image is formed on the photosensitive belt surface by passing it through charging station 10 and exposing station 20.
  • the charging station consists of any suitable means for placing a uniform charge on layer 64 such as corona charging device 11 shown in the drawing.
  • Exposing station 20 comprises projector 21 which projects and focuses a light pattern on the photosensitive surface conforming to the image to be reproduced by the xerographic system.
  • the image projected onto the photosensitive layer of the belt causes selective charge dissipation on elemental areas of layer 64 to form a latent electrostatic image thereon.
  • Other means for forming electrostatic images on insulating surfaces are known in the art and may be used instead of the one shown.
  • the photosensitive element After the formation of the latent electrostatic image by passing the photosensitive belt through stations 10 and 20, the photosensitive element is then forwarded to developing station 30.
  • a developer mixture comprising a toner powder composition and carrier material is cascaded over the belt surface whereby the toner particles are attracted to and deposited on the charged portions of the surface conforming to an image configuration.
  • the toner particles used generally consist of resinous electroscopic powder while the carrier material is a coarse, granular material generally re ferred to as carrier beads.
  • the development phenomenon occurs because of the fact that when the toner and carrier beads are mixed, toner particles are attracted to the large carrier bead nucleus through triboelectric attraction. Consequently, when the developer mixture is cascaded over the surface of the photosensitive belt the toner particles are attracted from their respective carrier beads and deposited on the photosensitive surface by the electrostatic charge pattern thereon.
  • the cascade development assembly comprises housing 31 containing a quantity of developer composition.
  • the mixture is lifted to an elevate'dposition over the photosensitive surface by buckets 34 which are supported on conveyor 33 which, in turn, is supported and driven by pulleys 35.
  • the development mixture lifted to the elevated position over the photosensitive surface is dumped onto the surface in the vicinity of the deflector plate 37.
  • the deflector plate directs the developer mixture onto the surface of the belt where it flows across said surface through development zone 39 and then into the trough 38 of housing 31.
  • the development zone 39 contains the development electrode of the present invention which is shown in greater detail in FIG. 2 and is spaced from the surface of the belt.
  • Development electrode 70 contains a plurality of taut, parallel spaced elongated wires 72 within housing 71 which enable the developer composition to flow freely within the gap between the development electrode and the photosensitive belt when the electrode is alligned in the direction of developer flow.
  • the deflection plate 37 developer composition cascades onto the and from there flows between the photosensitive belt surface and the development electrode whereupon the toner is picked up on the charged areas. Because of the parallel spaced taut wires of the electrode and their alignment generally parallel to the direction of developer flow, the developer composition is allowed to move continuously uninhibited along the extended planar surface of the photosensitive belt whereupon full development of the image bearing surface takes place.
  • the lower end 74 of the developer electrode extends beyond the lower end of the planar surface of the photosensitive belt whereby the excessive developer'can freely flow (as indicated by reference numeral 76) back into the trough 36 whereupon denuded carrier beads pick up more toner which is recycled again through the cascade development process.
  • the belt carries the developed image through transfer station 40 where the toner image is transferred from the photosensitive surface to support material 41.
  • Transfer of the developed image onto the support material is aided by a corona device 42 which applies an electrostatic charge having a polarity opposite that of a triboelectric charge on the toner particles to the support material.
  • Transfer takes place between guide rollers 45 which act to position the support material against the photosensitive belt at the transfer station.
  • Support material 41 is fed from reel 43 before transfer and is rewound on reel 44 after transfer takes place.
  • fusing device 46 is desirable and should be placed along the path of this support material between the point where the developed image is transferred to the support material and the point where the support material is rewound on reel 44.
  • the fusing device is positioned to heat the toner particles thereby permanently fixing them to the support material.
  • the final station shown in the drawing is cleaning station 50 comprising a cylindrical fur brush 51 which contacts the photosensitive surface of the belt.
  • the cleaning station is utilized to remove any residual toner particles from the photosensitive surface after transfer occurs and before a new image cycle is begun. It is intended that various moving elements be driven by any suitable means, for instance, the motor that drives the belt 63 can also, through appropriate gearing, drive all the other moving elements in the copier.
  • FIG. 2 there appears a frontal view of the development electrode of the present invention.
  • a plurality of spaced wires 72 are fixed tautly to housing 71.
  • the development electrode is placed in conjunction with the cascade development system such that the wires are substantially parallel to the direction of movement of the xerographic plate and also to the direction of developer flow.
  • the diameter of the wire as well as the distance between wires are critical elements in obtaining optimum results with respect to the instant development electrode. Should the wires be spaced too closely together, then jamming of the developer composition under-the wires will occur.
  • the diameter of thewire should be in the range of 0.004 to 0.050 inches and spaced at distances of from about 0.010 to 0.250 inches center to center spacing.
  • FIG. 3 demonstrates another embodiment of the present invention.
  • the development electrode is inclined at an angle to the direction of travel of the photoconductive belt surface 60.
  • the angle of the skewed development electrode has been accentuated in the drawing for purposes of illustration but in actual practice an angle of only a few degrees from the direction of belt travel is required to effeet the beneficial results of this particular embodiment.
  • the developer composition 36 flows in a direction counter to the direction of the photosensitive belt and encounters the development electrode. Because of the angle of the development electrode, accumulated toner is forced to flow across the belt surface in a manner such that total development necessarily takes place.
  • the slight angle of the development electrode not only insures complete development but also obviates the possibility of line gaps in the ultimate copy stemming from the total alignment of the taut parallel spaced wires in the direction of flow.
  • the development electrode be made of a suitable conducting material in that a sufficient number of parallel placed lines of such material be present to insure a continuous field.
  • the conducting material may consist of aluminum, stainless steel, copper, nickel and compositions thereof.
  • a xerographic reproduction unit including a photosensitive surface; means to form an electrostatic latent image on said surface and a developing apparatus for delivering two-component cascade developer to said surface at a developing station for cascade development of the latent image thereon;
  • a development electrode apparatus comprising a plurality of taut generally parallel spaced conductive members located in said development station and in a plane spaced from and generally parallel to said photosensitive surface;
  • said conductive members extending in the same general direction as the movement of the cascading developer
  • said conductive members each having a maximum cross sectional dimension of from about 0.004 to 0.050 inch and center to center spaced from each other from about 0.010 to 0.250 inch;
  • said photosensitive surface extending away from and at an angle to said plane of said conductive members at the lower end of the development station;
  • said conductive members extending substantially beyond the lower end of the development station to the extent that excessive developer freely flows off said photosensitive surface
  • the maximum cross sectional dimension of the conductive members is each no greater than about 0.010 inch and the conductive members are spaced from each other at a distance of no greater than about 0.045 inch.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Dry Development In Electrophotography (AREA)
  • Developing For Electrophotography (AREA)
US00172839A 1971-08-18 1971-08-18 Xerographic development electrode apparatus Expired - Lifetime US3778144A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US17283971A 1971-08-18 1971-08-18

Publications (1)

Publication Number Publication Date
US3778144A true US3778144A (en) 1973-12-11

Family

ID=22629451

Family Applications (1)

Application Number Title Priority Date Filing Date
US00172839A Expired - Lifetime US3778144A (en) 1971-08-18 1971-08-18 Xerographic development electrode apparatus

Country Status (6)

Country Link
US (1) US3778144A (nl)
JP (1) JPS5423587B2 (nl)
CA (1) CA972550A (nl)
DE (1) DE2239976C3 (nl)
GB (1) GB1393144A (nl)
NL (1) NL161898C (nl)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4050413A (en) * 1975-09-22 1977-09-27 Xerox Corporation Magnetic brush crossmixing system
US4120713A (en) * 1976-06-21 1978-10-17 A/S Weston Taeppefabrik Process and apparatus for the continuous production of a fibrous web-like pile product
US4133292A (en) * 1976-08-13 1979-01-09 Olympus Optical Company, Ltd. Wet-developing stationary electrode

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS572996Y2 (nl) * 1976-07-22 1982-01-19

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3011474A (en) * 1959-02-06 1961-12-05 Harold O Ulrich Xerographic development electrode apparatus
US3147147A (en) * 1961-06-05 1964-09-01 Xerox Corp Xerographic developing apparatus and electrode
US3331355A (en) * 1965-01-04 1967-07-18 Xerox Corp Xerographic developing apparatus
US3393663A (en) * 1966-07-21 1968-07-23 Xerox Corp Fluidizing electrode development apparatus
US3472657A (en) * 1965-04-30 1969-10-14 Xerox Corp Xerographic development method and apparatus
US3606863A (en) * 1969-02-12 1971-09-21 Xerox Corp Development electrode

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3011474A (en) * 1959-02-06 1961-12-05 Harold O Ulrich Xerographic development electrode apparatus
US3147147A (en) * 1961-06-05 1964-09-01 Xerox Corp Xerographic developing apparatus and electrode
US3331355A (en) * 1965-01-04 1967-07-18 Xerox Corp Xerographic developing apparatus
US3472657A (en) * 1965-04-30 1969-10-14 Xerox Corp Xerographic development method and apparatus
US3393663A (en) * 1966-07-21 1968-07-23 Xerox Corp Fluidizing electrode development apparatus
US3606863A (en) * 1969-02-12 1971-09-21 Xerox Corp Development electrode

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4050413A (en) * 1975-09-22 1977-09-27 Xerox Corporation Magnetic brush crossmixing system
US4120713A (en) * 1976-06-21 1978-10-17 A/S Weston Taeppefabrik Process and apparatus for the continuous production of a fibrous web-like pile product
US4133292A (en) * 1976-08-13 1979-01-09 Olympus Optical Company, Ltd. Wet-developing stationary electrode

Also Published As

Publication number Publication date
NL161898C (nl) 1980-03-17
JPS4831953A (nl) 1973-04-26
CA972550A (en) 1975-08-12
NL161898B (nl) 1979-10-15
JPS5423587B2 (nl) 1979-08-15
DE2239976A1 (de) 1973-04-05
DE2239976C3 (de) 1980-06-12
NL7211096A (nl) 1973-02-20
DE2239976B2 (de) 1979-09-13
GB1393144A (en) 1975-05-07

Similar Documents

Publication Publication Date Title
US3011474A (en) Xerographic development electrode apparatus
US3620615A (en) Sheet stripping apparatus
US3649262A (en) Simultaneous development-cleaning of the same area of an electrostatographic image support surface
US3641980A (en) Development apparatus
US3638614A (en) Electrostatic latent image development apparatus
US3412710A (en) Cleanup electrode
US3416494A (en) Xerographic development electrode
US3791730A (en) Apparatus for developing electrostatic latent images
US3572289A (en) Magnetic brush development apparatus
US3584601A (en) Magnetic brush belt development
US4210448A (en) Process for electrophotographic image formation and transfer
JPH0740167B2 (ja) 電子写真装置用のバイアスした掃去グリッド
US3662711A (en) Development apparatus
US3719169A (en) Plural electrode development apparatus
US3778144A (en) Xerographic development electrode apparatus
US5184194A (en) Carrier particle scavenging device
US3357403A (en) Powder cloud development apparatus
US4139296A (en) Cross mixer
US3543022A (en) Method and apparatus for charging discrete small areas of xerographic plates to different potentials in continuous tone printing
US3492476A (en) Electrostatic charging device utilizing both a.c. and d.c. fields
US3532494A (en) Solid area development in xerography employing an insulating screen in the charging step
US3592166A (en) Apparatus for developing electrostatic images
US3807997A (en) Plural electrode development methods for latent electrostatic images
US3166420A (en) Simultaneous image formation
JPH0560104B2 (nl)