US3678897A - Developer mixing apparatus - Google Patents

Developer mixing apparatus Download PDF

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Publication number
US3678897A
US3678897A US110489A US3678897DA US3678897A US 3678897 A US3678897 A US 3678897A US 110489 A US110489 A US 110489A US 3678897D A US3678897D A US 3678897DA US 3678897 A US3678897 A US 3678897A
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US
United States
Prior art keywords
toner
developer material
chute
developer
magnetic
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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
US110489A
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English (en)
Inventor
Robert E Hewitt
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Xerox Corp
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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
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Publication of US3678897A publication Critical patent/US3678897A/en
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
    • 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

  • ABSTRACT improved cascade apparatus for developing electrostatic images wherein a latent electrostatic image supported on a moving member is developed by cascading a flow of developer material including a magnetic carrier component and an electroscopic toner component through a development zone.
  • a toner dispenser dispenses toner material to supplement that portion consumed during development.
  • the dispensed toner material is received onto a chute which directs the toner material into a predetermined location in the sump of the developer housing.
  • a bucket conveyor moves developer material upwardly in the housing and spillage from the buckets is directed along the chute to combine with the dispensed toner material and also to prevent the dispensed toner material from clinging on the chute.
  • a magnetic field producing member is positioned on the chute adjacent the path of the bucket conveyor to control the direction of flow of the spillage and to pull excess developer material from the buckets.
  • This invention relates to an improved cascade development apparatus which increases the uniformity of mix of two component developer material loaded from a sump and unloaded from a bucket conveyor to an entrance chute leading to a cascade development zone for a more efficient development.
  • a xerographic plate formed of a conductive backing material upon which is placed a conductive insulating material is charged uniformly in the surface of the plate exposed to a light image of an original to be reproduced.
  • the photoconductive coating is caused to become conductive under the influence of the light image so as to selectively dissipate the electrostatic charge found thereon thus producing an electrostatic latent image.
  • the latent image is then developed by means of a variety of finely divided pigmented resins which have been specifically developed for this purpose.
  • the pigmented resin material or toner is electrostatically attracted to the latent image on the photoconductive surface in proportion to the ion charge found thereon that is areas of small charge concentration become areas of low toner density whileareas of greater charge concentration become proportionately more dense, the fully developed images generally transferred to a support material, as for example, paper and the image fixed thereto to form a permanent record of the original document.
  • cascade development In which a two component developer material is caused to flow down over the moving image bearing photoconductive surface to effect image development.
  • the toner and carrier material are triboelectrically charged to opposite polarities and the particulate toner material adheres to the carrier in a charged state.
  • the toner laden carrier beads flow over the photoconductive surface, the toner is electrostatically stripped from the carrier and attracted to the plate surface by the relatively stronger force fields associated with the imaged areas.
  • Cascade development has a high development latitude and is particularly noteworthy in freedom from background deposition. Further, the process is dependable and operates with high efficiency under extreme humidity conditions and is easily converted to give either positive or reverse reproduction of the original document to be copied.
  • cascade development there are, however, certain problems which may result with cascade development, as for example, solid areas and tonal patterns may not develop well especially if the proper mixture of carrier to toner is not maintained as toner is consumed. Also, cascade development under certain conditions, such as high electrostatic contrast, may result in carrier beads sticking to the photoconductive surface.
  • a recent tendency has been to use a cascade development process for development of the electrostatic images using a high density developer material including a magnetic carrier component with the electroscopic toner component and it is the purpose of the present invention to improve cascade development in this sense.
  • FIG. 1 is a schematic side elevation of a continuous automatic xerographic reproducing machine having a cascade development zone and incorporating development apparatus constructed in accordance with the instant invention
  • FIG. 2 is an enlarged partial sectional view of cascade developing apparatus according to the present invention.
  • FIG. 3 is an enlarged portion of FIG. 2 illustrating certain details of the present invention.
  • FIG. 1 an embodiment of the subject invention in a suitable environment such as an automatic xerographic reproducing machine employing a drum shaped xerographic plate 10 comprising a photoconductive layer which is placed on a conductive backing and is moved in an uphill direction in the development zone on a shaft 12 journaled in the machine frame.
  • the rotation causes the plate surface to sequentially pass a series of xerographic processing stations.
  • the several xerographic processing stations in the path of moving of the plate surface may be described functionally as follows:
  • the development station includes a conveyor assembly 14 for transporting developer material from a sump 16 to an elevated location.
  • the developer material comprises a mixture of any suitable magnetic carrier particles and an electroscopic toner powder with the toner powder adhering to the carrier as a result of the triboelectric effect.
  • Typical carrier materials comprise powdered iron including the types known commercially as alcoholized iron and carboxal iron, steel nickel, alloys of magnetic iron such as nickel-iron alloys, nickel-cobalt iron alloys, and magnetic oxides, such as iron oxide, hematite (F6 and magnetite (Fe-p and ferromagnetic ferrites.
  • the ferromagnetic material may be used as a core covered with a resinous coating having the desired triboelectric properties as described, for example, in U.S. Pat. No. 2,618,551 to Walkup and U.S. Pat. No. 2,874,063 to Greog.
  • Typical'electroscopic toner powders are described in U.S. Pat. No. 2,618,551 to Walkup, U.S. Pat. No. 2,618,552 to Wise, and U.S. Pat. No. 2,638,416 to Walkup and Wise.
  • the conveyor assembly 14 includes a plurality of buckets stapled or otherwise suitably secured to endless belts 22 mounted on upper pulleys 24 and lower pulleys 26 for movement in a path of travel indicated by the arrow.
  • the lowermost pulleys are located so that the buckets can pass through the sump 16 of development material beneath the cascade development zone 28.
  • the sump is continually reloaded with developer falling from the cascade development zone and captured and directed by a pickoff baffle 30.
  • Above the development zone is an input chute 32 receiving the conveyed developer material as it is unloaded or dumped from the buckets and gravity dropped for cascading through the development zone. Due to the fact that toner particles are lost from the development system through the development of the electrostatic images on the xerographic drum, a toner dispenser 36 is employed to replenish that consumed from the system.
  • a chute member 40 is positioned to receive toner material dispensed and direct the flow of the material towards one side of sump 16 adjacent to the path of bucket conveyor 14. Because the toner material is a very fine powder there is a tendency for clumps to form on the chute 40. It will be noted that chute 40 is positioned to receive developer spillage from buckets 20.
  • a magnet member 45 is positioned in close proximity to the chute member with pole faces N and S arranged at right angles to the surface of the chute member. By this arrangement the chute member which is made out of magnetic material serves as an extended pole face of the magnet member. Due to the magnetic field established from magnet member 45 and chute member 40 developer material spilled is directed across the chute member 40 where it combines with toner material being dispensed.
  • chute member 40 is made of a magnetic material, the magnetic lines of force will be shielded from the top surface of the chute member to prevent sticking of developer material along the upper surface of the chute members.
  • An apparatus dispensing toner to a cascade development station wherein a latent electrostatic image is developed by cascade flow of developer material including a magnetic component and an electroscopic toner component moving through a development zone, the improvement comprising a housing including a sump portion containing developer material including a magnetic component and an electroscopic component,
  • conveyor means including buckets disposed in the housing for moving developer material from the sump portion to an upper portion of the housing for downward cascade flow onto a latent electrostatic image moving in a development zone,
  • toner dispenser means positioned in said housing for dispensing toner material at predetermined intervals, chute means disposed below said toner dispenser means for directing the flow of the toner material towards a predetermined location of said sump portion,
  • said chute means extending towards said bucket path to receive back spillage of developer material being dropped from said upwardly moving buckets and having a magnetic field producing means associated therewith to pull excess developer material from said buckets and direct the excess developer material and spilled developer material along a predetermined path intersecting with the path of dispensed toner material whereby toner material being dispensed is continuously supplied into said sump portion for uniform mixing with developer material therein.
  • Apparatus according to claim 2 wherein the magnetic field producing means is a magnet member positioned with its poll faces extending at right angles to the magnetic member.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Dry Development In Electrophotography (AREA)
  • Developing Agents For Electrophotography (AREA)
US110489A 1971-01-28 1971-01-28 Developer mixing apparatus Expired - Lifetime US3678897A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US11048971A 1971-01-28 1971-01-28

Publications (1)

Publication Number Publication Date
US3678897A true US3678897A (en) 1972-07-25

Family

ID=22333295

Family Applications (1)

Application Number Title Priority Date Filing Date
US110489A Expired - Lifetime US3678897A (en) 1971-01-28 1971-01-28 Developer mixing apparatus

Country Status (9)

Country Link
US (1) US3678897A (ja)
JP (1) JPS5423255B1 (ja)
BE (1) BE778426A (ja)
CA (1) CA951113A (ja)
DE (1) DE2204082A1 (ja)
FR (1) FR2124988A5 (ja)
GB (1) GB1377151A (ja)
IT (1) IT946909B (ja)
NL (1) NL7200932A (ja)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4051484A (en) * 1975-11-03 1977-09-27 Martin Samuel W Magnetic printer and method of performing same
US20030224279A1 (en) * 2002-03-22 2003-12-04 Akihiro Kotsugai Carrier for developer for developing electrostatic latent image, developer using same and image forming method using same

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3348521A (en) * 1962-08-28 1967-10-24 Xerox Corp Automatic toner control system
US3367307A (en) * 1965-06-02 1968-02-06 Arlside Ltd Electrostatographic developing apparatus
US3572289A (en) * 1968-09-23 1971-03-23 Xerox Corp Magnetic brush development apparatus
US3611982A (en) * 1969-08-29 1971-10-12 Xerox Corp Development electrode control apparatus

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3348521A (en) * 1962-08-28 1967-10-24 Xerox Corp Automatic toner control system
US3367307A (en) * 1965-06-02 1968-02-06 Arlside Ltd Electrostatographic developing apparatus
US3572289A (en) * 1968-09-23 1971-03-23 Xerox Corp Magnetic brush development apparatus
US3611982A (en) * 1969-08-29 1971-10-12 Xerox Corp Development electrode control apparatus

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4051484A (en) * 1975-11-03 1977-09-27 Martin Samuel W Magnetic printer and method of performing same
US20030224279A1 (en) * 2002-03-22 2003-12-04 Akihiro Kotsugai Carrier for developer for developing electrostatic latent image, developer using same and image forming method using same
US7320852B2 (en) * 2002-03-22 2008-01-22 Ricoh Company, Ltd. Carrier for developer for developing electrostatic latent image, developer using same and image forming method using same

Also Published As

Publication number Publication date
NL7200932A (ja) 1972-08-01
JPS5423255B1 (ja) 1979-08-13
GB1377151A (en) 1974-12-11
FR2124988A5 (ja) 1972-09-22
DE2204082A1 (de) 1972-08-10
BE778426A (fr) 1972-07-24
CA951113A (en) 1974-07-16
IT946909B (it) 1973-05-21

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