US3257224A - Method and apparatus for developing electrostatic images - Google Patents

Method and apparatus for developing electrostatic images Download PDF

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Publication number
US3257224A
US3257224A US247025A US24702562A US3257224A US 3257224 A US3257224 A US 3257224A US 247025 A US247025 A US 247025A US 24702562 A US24702562 A US 24702562A US 3257224 A US3257224 A US 3257224A
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US
United States
Prior art keywords
roller
developer
trough
toner
magnetic
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
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US247025A
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English (en)
Inventor
Jons Kurt
Wolfinger Arthur
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.)
Azoplate Corp
Original Assignee
Azoplate Corp
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Filing date
Publication date
Application filed by Azoplate Corp filed Critical Azoplate Corp
Application granted granted Critical
Publication of US3257224A publication Critical patent/US3257224A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • G03G15/09—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer using magnetic brush
    • G03G15/0921—Details concerning the magnetic brush roller structure, e.g. magnet configuration

Definitions

  • the developers normally used in electrophotography consist of a mixture of finely divided resinous toner and a carrier for the toner of somewhat larger particle size than the toner.
  • the carrier is often of magnetizable material, e.g. iron filings, in order to enable the developer to be applied with the aid of a rotating magnetic roller to the surface of a latent electrostatic image.
  • the magnetic roller which may be a permanent magnet or may be magnetized by an electric current, dip into developer powder contained in a trough beneath the roller.
  • the toner is attracted electrostatically from the magnet to the photoconductive coating of the electrophotographic material and a visible image is formed.
  • the developer, depleted in toner is returned to the trough as the magnetic roller rotates.
  • the iron filings always come to rest at the same place, namely near the point at which renewed magnetization of the poles occurs so that the mixing operation in the trough, which can be carried out at a limited speed only and which is intended to load the iron filings with new toner, cannot take place sufiiciently rapidly.
  • the roller therefore continually picks up the toner-depleted iron filings which have just been dropped as a result of the demagnetization.
  • the present invention provides an apparatus for developing latent electrostatic images comprising a trough to contain a developer mixture of iron filings and toner powder, an agitator in the trough, an electromagnetically excited iron roller for picking up developer from the trough and transferring it to the electrophotographic material to be developed, the iron roller being made of up of rotor plates having a number of windings to which exciting current is supplied intermittently, being cut off once in every revolution of the roller and a covering of synthetic plastic 3,257,224 Patented June 21, 1956 material, and a deflector plate which coacts with the portion of the roller traveling away from the electrophotographic material and towards the developer contained in the trough to deflect towards the wall of the trough developer shed by the roller while the current is cut off.
  • the laminations of the roller consists of relatively thin soft iron sheets placed side by side with layers 'of insulating material between them.
  • the shape of these plates corresponds to the cross section of the intended roller. If the notches provided for the windings are even in number, particularly good results can be obtained.
  • the covering on the roller mayconsist of any suitable insulating plastic which is solid at normal temperatures.
  • suitable plastics are thermoplastics, such as polyolefins, e.g. polyethylene and polypropylene, polyvinyl compounds such as polyvinyl chloride, polyamides and polyesters.
  • thermosetting resins e.g. phenolformaldehyde resins.
  • plastics such as those used for insulating purposes in transformers; they are described, for example, in the handbook of Messrs. lSchgamm, Lackund, Wegrik AG, Elektro-Isolierac e.
  • the plastic coating can be applied by placing the magnetic roller in a mold, the gap between the inner Walls of mold and the surface of the magnetic roller being greater than the thickness of the plastic coating which is to be produced on the surface of the roller.
  • the intermediate spaces are now filled with a substance which contains unhardened components of a resin mixture together with a hardener. The whole is then allowed to 'stand for 20-30 hours, during which time the plastic hardens completely. After removing the roller from the mold, it is advantageous for'the surface of the plastic coating to be evened and smoothed by turning.
  • the plastic covering may also be applied to the roller by painting on a mixture of the plastic substance and a hardener.
  • the thickness of the painted coating is advantageously considerably greater than the thickness finally required.
  • the surface of the plastic coating is again finished by turning and polishing.
  • Plastic coatings, particularly thermoplastic coatings can also be applied to the roller surface in the form of ready made foils by wrapping and, where necessary, fusing.
  • the thickness of the plastic coating on the surface of the electromagnetic roller is generally between 0.2 and 1.0 mm. preferably 0.4-0.5 mm., but lesser or greater thicknesses can also be successfully used.
  • the surface of the plastic coating on the magnetic roller may be made electrically conducting and may be provided with a bias voltage with respect to the surface of the photoconductive layer of the electrophotographic material or it may be grounded. This is particularly advantageous in the case of the development of latent electrostatic images which, because of inadequate exposure, have a residual charge in the image-free parts.
  • the surface can, for example, be made conductive by treatment with a dispersion of silver particles in a suitable dispersion agent, e.g. the so-called Leitsilber (conducting silver), or it can be .coated with metal. Good results are also obtained by the application of a thin metal foil to the roller.
  • a suitable dispersion agent e.g. the so-called Leitsilber (conducting silver)
  • Leitsilber conducting silver
  • the deflector plate extends over the whole width of the electromagnetic roller.
  • the distance of the deflector plate from the surface of the roller should be kept as small as possible.
  • the length of the surface of the deflector plate over which the toner-depleted carrierruns should be as great as possible.
  • the deflector plate should discharge the carrier near to the wall of the trough.
  • the deflector plate can be joined underneath with the normally used securing devices to the wall of the vessel.
  • the apparatus may include a container for toner powder adjacent the trough and means for periodically delivering measured quantities of toner powder from the container to the trough.
  • FIGURE 1 is a transverse section through the developing apparatus
  • FIGURE 2 is a plan view
  • FIGURE 3 is a longitudinal section through the developing apparatus
  • FIGURE 4 shows the current supply member in crosssection
  • FIGURE 4a shows the current supply member in plan view.
  • the apparatus includes an electromagnetically excited roller 1 having a shaft 2 which is journaled in bearings 3 and 4 and is driven by the gears 5, 6 and 7.
  • the windings 9 of the roller 1 receive current from a source, not shown, of direct current via individual slip rings 10. 1
  • the roller 1 has twelve grooves 9' containing six separate windings which are excited by means of six slip rings 10 which coact with the brushes 26.
  • the roller 1 also has a coating 11 of synthetic plastic material. Between points 12 and 13, the slip rings 10 are provided with means for interrupting the current.
  • the roller rotates anticlockwise as viewed in FIGURE 4 and, as soon as the windings 9 have passed the point 13, they are deprived of current.
  • the developer carried by the roller is then dropped off and is deflected by a deflector plate 14 to the outer edge of the developer trough.
  • the discarded developer works its way very slowly back from the outer edge of the developer trough 14' to the agitator 15 in the trough and is taken up by the agitator and, after intensive mixing, passed to the point 12, at which magnetization of the roller recommences, and is there taken up by the roller.
  • the plastic coating 11 on the magnetic roller 1 ensures that after the current has been switched off at the point 13 the developer will not remain attracted by residual magnetism.
  • the trough is replenished with toner in a simple manner and without dust by the following mechanism:
  • a container 17 (FIG. 3) contains a certain quantityof toner for purposes of replenishment.
  • the trough is replenished with toner from the container 17 by dosing plungers 18.
  • End plates 19 on the plungers 18 normally close the feed opening 20 in the wall of the container 17 and the plungers carry sealing sleeves 21.
  • the plungers, which are fitted with return springs 24, are actuated by rocker arms 22 from a motordriven eccentric 23, which is driven at a speed appropriate to requirements.
  • the toner in the container 17 is agitated by a vane 25 which is vibrated by a rocker magnet.
  • Apparatus for developing latent electrostatic images comprising a trough adapted to contain a developer having a magnetic component, a rotatable electrically magnetizable roller mounted in the trough, the roller having a plurality of separate windings and an insulating layer on the roller surface, means for supplying and interrupting an electric current to at least one of the windings during rotation of the roller to thereby successively magnetize and demagnetize portions of the roller surface, and defleeting means mounted adjacent the roller.
  • Apparatus according to claim 1 including a container adapted to contain toner mounted adjacent the trough and means for delivering measured quantities of toner to the trough.
  • a process for applying a developer to a latent electrostatic image which comprises electrically generating a magnetic field in portions of a surface of a rotatable applicator submerged in a body of developer having a magnetic component, rotating the said portions of the surface carrying developer thereon into contact with the latent electrostatic image, rotating the said portions of the surface out of contact with the electrostatic image and interrupting the electric current, thereby eliminating the magnetic field from said portions of said surface, and passing excess developer from said portions of said surface back into the body of developer at a point remote from the initial position of the developer in the body.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Magnetic Brush Developing In Electrophotography (AREA)
US247025A 1961-12-27 1962-12-26 Method and apparatus for developing electrostatic images Expired - Lifetime US3257224A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DEK0045522 1961-12-27

Publications (1)

Publication Number Publication Date
US3257224A true US3257224A (en) 1966-06-21

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ID=7223876

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Application Number Title Priority Date Filing Date
US247025A Expired - Lifetime US3257224A (en) 1961-12-27 1962-12-26 Method and apparatus for developing electrostatic images

Country Status (4)

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US (1) US3257224A (ja)
BE (1) BE626526A (ja)
GB (1) GB976998A (ja)
NL (1) NL286833A (ja)

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3318284A (en) * 1964-01-30 1967-05-09 Hitachi Ltd Apparatus for developing electrostatic images of records
US3574301A (en) * 1969-04-02 1971-04-13 Xerox Corp Developing apparatus
US3996892A (en) * 1975-02-24 1976-12-14 Xerox Corporation Spatially programmable electrode-type roll for electrostatographic processors and the like
US3998185A (en) * 1975-02-03 1976-12-21 Xerox Corporation Microfield donors with toner agitation and the methods for their manufacture
US4017648A (en) * 1975-02-03 1977-04-12 Xerox Corporation Toner agitation through microfield donor
US4086873A (en) * 1974-07-09 1978-05-02 Konishiroku Photo Industry Co., Ltd. Electrophotographic developing device incorporating a developing electrode having an insulation layer on its surface
US5063412A (en) * 1990-09-26 1991-11-05 Xerox Corporation Development apparatus using an electromagnet to prevent development in the non-operative mode
US5289240A (en) * 1993-05-20 1994-02-22 Xerox Corporation Scavengeless developer unit with electroded donor roll
US5360940A (en) * 1993-07-14 1994-11-01 Xerox Corporation Scavengeless two component development with an electroded development roll
EP0691586A1 (en) 1994-07-05 1996-01-10 Xerox Corporation Development apparatus having an adjustable width development nip
US5500969A (en) * 1994-10-24 1996-03-26 Xerox Corporation Dual polarity commutated roll elctrostatic cleaner with acoustic transfer assist
US5570169A (en) * 1995-09-25 1996-10-29 Xerox Corporation Donor rolls with modular commutation
US5589917A (en) * 1995-09-25 1996-12-31 Xerox Corporation Donor rolls with magnetically coupled (Transformer) commutation
US5592271A (en) * 1996-01-11 1997-01-07 Xerox Corporation Donor rolls with capacitively cushioned commutation
US5594534A (en) * 1996-01-11 1997-01-14 Xerox Corporation Electroded doner roll structure incorporating resistive network
US5600418A (en) * 1995-09-25 1997-02-04 Xerox Corporation Donor rolls with exterior commutation
US5614995A (en) * 1995-09-05 1997-03-25 Xerox Corporation Electroded donor roll having robust commutator contacts
US5745827A (en) * 1997-03-31 1998-04-28 Xerox Corporation Bundled steel wire SED communicator secondary cores

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3687106A (en) * 1969-07-11 1972-08-29 Xerox Corp Donor apparatus and method

Citations (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US404465A (en) * 1889-06-04 Electric motor
US500400A (en) * 1893-06-27 Philip lange
US673980A (en) * 1900-06-22 1901-05-14 Harry M Mcnelly Electromagnet-motor.
US1048223A (en) * 1908-11-28 1912-12-24 Heinrich Stein Electromagnetic separator.
US1177981A (en) * 1914-05-14 1916-04-04 Parvin Wright Magnetic separator.
US1362072A (en) * 1917-11-17 1920-12-14 Arnold Horace Wade Magnetic ore-separator
US1371301A (en) * 1920-08-21 1921-03-15 Converse Henry Combined feeder and magnetic separator
US1449371A (en) * 1919-09-15 1923-03-27 Vincent G Apple Method of constructing armatures for dynamo-electric machines
US2449021A (en) * 1942-06-08 1948-09-07 Hoover Co Dynamoelectric machine
US2711249A (en) * 1954-05-20 1955-06-21 Fur Unternehmungen Der Eisen U Drum magnet separator
US2779306A (en) * 1955-03-25 1957-01-29 Ibm Electroscopic toner metering device
US2832311A (en) * 1956-01-10 1958-04-29 Haloid Co Apparatus for development of electrostatic images
US2844489A (en) * 1957-12-20 1958-07-22 Knapsack Ag Fluidized bed coating process
US2896101A (en) * 1957-05-03 1959-07-21 United Aircraft Corp Differential tachometer
US2904000A (en) * 1957-05-15 1959-09-15 Century Geophysical Corp Magnetic-brush developer
US2956487A (en) * 1955-03-23 1960-10-18 Rca Corp Electrostatic printing
US2975758A (en) * 1958-03-13 1961-03-21 Haloid Xerox Inc Apparatus for developing electrostatic images
US2992733A (en) * 1957-10-09 1961-07-18 Indiana General Corp Magnetic pulley and permanent magnet therefor
US3003462A (en) * 1957-01-18 1961-10-10 Bruning Charles Co Inc Apparatus for applying developer powder to photo-conductive insulating sheets
US3028266A (en) * 1957-11-04 1962-04-03 Everett P Larsh Method and apparatus for impregnating motor windings and motor stator
US3028708A (en) * 1960-01-08 1962-04-10 Columbus M Vaughan Blast cleaning machines
US3040704A (en) * 1957-04-16 1962-06-26 Rca Corp Apparatus for developing electrostatic printing
US3081737A (en) * 1961-03-01 1963-03-19 Gen Aniline & Film Corp Xerographic apparatus for applying ferromagnetic powder
US3088386A (en) * 1959-11-16 1963-05-07 American Photocopy Equip Co Electrophotographic photocopy machine
US3098765A (en) * 1959-03-16 1963-07-23 Robertson Photo Mechanix Inc Xerographic brush
US3152924A (en) * 1961-05-24 1964-10-13 Robertson Photo Mechanix Inc Xerographic brush

Patent Citations (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US500400A (en) * 1893-06-27 Philip lange
US404465A (en) * 1889-06-04 Electric motor
US673980A (en) * 1900-06-22 1901-05-14 Harry M Mcnelly Electromagnet-motor.
US1048223A (en) * 1908-11-28 1912-12-24 Heinrich Stein Electromagnetic separator.
US1177981A (en) * 1914-05-14 1916-04-04 Parvin Wright Magnetic separator.
US1362072A (en) * 1917-11-17 1920-12-14 Arnold Horace Wade Magnetic ore-separator
US1449371A (en) * 1919-09-15 1923-03-27 Vincent G Apple Method of constructing armatures for dynamo-electric machines
US1371301A (en) * 1920-08-21 1921-03-15 Converse Henry Combined feeder and magnetic separator
US2449021A (en) * 1942-06-08 1948-09-07 Hoover Co Dynamoelectric machine
US2711249A (en) * 1954-05-20 1955-06-21 Fur Unternehmungen Der Eisen U Drum magnet separator
US2956487A (en) * 1955-03-23 1960-10-18 Rca Corp Electrostatic printing
US2779306A (en) * 1955-03-25 1957-01-29 Ibm Electroscopic toner metering device
US2832311A (en) * 1956-01-10 1958-04-29 Haloid Co Apparatus for development of electrostatic images
US3003462A (en) * 1957-01-18 1961-10-10 Bruning Charles Co Inc Apparatus for applying developer powder to photo-conductive insulating sheets
US3040704A (en) * 1957-04-16 1962-06-26 Rca Corp Apparatus for developing electrostatic printing
US2896101A (en) * 1957-05-03 1959-07-21 United Aircraft Corp Differential tachometer
US2904000A (en) * 1957-05-15 1959-09-15 Century Geophysical Corp Magnetic-brush developer
US2992733A (en) * 1957-10-09 1961-07-18 Indiana General Corp Magnetic pulley and permanent magnet therefor
US3028266A (en) * 1957-11-04 1962-04-03 Everett P Larsh Method and apparatus for impregnating motor windings and motor stator
US2844489A (en) * 1957-12-20 1958-07-22 Knapsack Ag Fluidized bed coating process
US2975758A (en) * 1958-03-13 1961-03-21 Haloid Xerox Inc Apparatus for developing electrostatic images
US3098765A (en) * 1959-03-16 1963-07-23 Robertson Photo Mechanix Inc Xerographic brush
US3088386A (en) * 1959-11-16 1963-05-07 American Photocopy Equip Co Electrophotographic photocopy machine
US3028708A (en) * 1960-01-08 1962-04-10 Columbus M Vaughan Blast cleaning machines
US3081737A (en) * 1961-03-01 1963-03-19 Gen Aniline & Film Corp Xerographic apparatus for applying ferromagnetic powder
US3152924A (en) * 1961-05-24 1964-10-13 Robertson Photo Mechanix Inc Xerographic brush

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3318284A (en) * 1964-01-30 1967-05-09 Hitachi Ltd Apparatus for developing electrostatic images of records
US3574301A (en) * 1969-04-02 1971-04-13 Xerox Corp Developing apparatus
US4086873A (en) * 1974-07-09 1978-05-02 Konishiroku Photo Industry Co., Ltd. Electrophotographic developing device incorporating a developing electrode having an insulation layer on its surface
US3998185A (en) * 1975-02-03 1976-12-21 Xerox Corporation Microfield donors with toner agitation and the methods for their manufacture
US4017648A (en) * 1975-02-03 1977-04-12 Xerox Corporation Toner agitation through microfield donor
US3996892A (en) * 1975-02-24 1976-12-14 Xerox Corporation Spatially programmable electrode-type roll for electrostatographic processors and the like
US5063412A (en) * 1990-09-26 1991-11-05 Xerox Corporation Development apparatus using an electromagnet to prevent development in the non-operative mode
US5289240A (en) * 1993-05-20 1994-02-22 Xerox Corporation Scavengeless developer unit with electroded donor roll
US5360940A (en) * 1993-07-14 1994-11-01 Xerox Corporation Scavengeless two component development with an electroded development roll
US5491538A (en) * 1994-07-05 1996-02-13 Xerox Corporation Development apparatus having an adjustable width development nip
EP0691586A1 (en) 1994-07-05 1996-01-10 Xerox Corporation Development apparatus having an adjustable width development nip
US5500969A (en) * 1994-10-24 1996-03-26 Xerox Corporation Dual polarity commutated roll elctrostatic cleaner with acoustic transfer assist
EP0709751A2 (en) 1994-10-24 1996-05-01 Xerox Corporation Apparatus for cleaning particles from a surface
US5614995A (en) * 1995-09-05 1997-03-25 Xerox Corporation Electroded donor roll having robust commutator contacts
US5570169A (en) * 1995-09-25 1996-10-29 Xerox Corporation Donor rolls with modular commutation
US5589917A (en) * 1995-09-25 1996-12-31 Xerox Corporation Donor rolls with magnetically coupled (Transformer) commutation
US5600418A (en) * 1995-09-25 1997-02-04 Xerox Corporation Donor rolls with exterior commutation
US5592271A (en) * 1996-01-11 1997-01-07 Xerox Corporation Donor rolls with capacitively cushioned commutation
US5594534A (en) * 1996-01-11 1997-01-14 Xerox Corporation Electroded doner roll structure incorporating resistive network
EP0785485A2 (en) 1996-01-11 1997-07-23 Xerox Corporation Electrodes donor roll structures incorporating resistive networks
EP0786707A2 (en) 1996-01-11 1997-07-30 Xerox Corporation Donor rolls with capacitively cushioned commutation
US5745827A (en) * 1997-03-31 1998-04-28 Xerox Corporation Bundled steel wire SED communicator secondary cores

Also Published As

Publication number Publication date
NL286833A (ja)
GB976998A (en) 1964-12-02
BE626526A (ja)

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