US3626898A - High-speed magnetic brush developer apparatus - Google Patents

High-speed magnetic brush developer apparatus Download PDF

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Publication number
US3626898A
US3626898A US9316A US3626898DA US3626898A US 3626898 A US3626898 A US 3626898A US 9316 A US9316 A US 9316A US 3626898D A US3626898D A US 3626898DA US 3626898 A US3626898 A US 3626898A
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United States
Prior art keywords
cylinder
zone
developer
station
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
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US9316A
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English (en)
Inventor
Stanley A Gawron
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AB Dick Co
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Multigraphics Inc
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Publication date
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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

  • a high-speed magnetic brush assembly is provided in which an array of magnets are arranged inside a nonmagnetic cylinder to control the movement of the developer mixture of iron powder and toner.
  • the cylinder rotates about the fixed magnets.
  • One set of magnets attracts a quantity of mix to the cylinder and subsequent magnets transport the mix to the next station where a single or multiple magnets brush develops the paper.
  • the magnet discharges the mix from the cylinder.
  • the assembly is enclosed to contain the mix and includes a spillway for the mix leading to mixing chambers where the mix is reconditioned for reuse.
  • developer brushes useful in photoelectrostatic copying is well known and is a well-developed art.
  • the principles of operation are well defined calling for magnetic means mounted inside a rotating cylinder which is partially immersed in a supply of magnetically attractable developer mix. As the cylinder rotates, a quantity of the developer mix is accumulated on its surface in a brushlike formation which is then caused to sweep across a photoconductive member carrying a latent electrostatic image thereon thereby developing the image.
  • the magnetic brush assembly of the instant invention achieved a high-degree of success in such high-speed systems by utilizing the magnetic fields of force to create specific zones within the magnetic flux field generated by the magnetic means through which the surface of the cylinder rotates.
  • the device of the present invention provides an applicator drum having zones with varying magnetic field strengths which selectively pick up, convey, form a developer brush and then discharge the mass from the surface of the applicator to a collector.
  • the system provides for recycling the mix after each application so the mix is given an opportunity to be replenished with fresh toner.
  • the present invention provides a magnetic brush developer unit for a photoelectrostatic copying machine that is particularly suited to a high-rate of copy output while protecting the granular developer mix from undue cornminution and throwout of fine particles into the atmosphere.
  • FIG. 3 is a vertical cross section of another form of a developer showing the magnetic field generating means and the resulting magnetic flux distribution at the various zonal areas.
  • FIG. 1 the magnetic brush developer assembly identified generally with the reference character 10 equipped with a pair of infeed rollers l2 and 14 which direct the paper into the developing station identified generally as 16.
  • a pair of spaced apart guide elements 18 and 20 Leading from the infeed rollers 12 and 14 a pair of spaced apart guide elements 18 and 20 forming a throat 22 through which the sheet is guided into the developing station 16.
  • a rod 21 which is part of the paper guide 20, controls the height of the developer mix on the cylinder that can enter the developing station.
  • a set of feedout rollers 24 and 26 which provide an exitway for the paper from the developing station. Included in the exitway construction is a guide element 28 that receives the lead edge of the sheet guiding it into the nip of the feed-out rollers 24 and 26.
  • an enclosure 34 which includes a developing electrode 36 whose function and operation is fully described in U.S. Pat. No. 3,369,917, issued to Daniel Granzow, et al., issued Feb. 20, 1968.
  • a hollow cylinder 40 which is rotatably mounted on a fixed shaft 42, the hollow cylinder being suitably supported on the shaft by bearing members 43.
  • the shaft 42 is appropriately secured at its one end to the side frame of the apparatus. The other end of the shaft 42 terminates inside the cylinder 40 being received in one of the bearing members 43.
  • a magnetic flux generating assembly 44 which includes an array of several magnets disposed within the cylinder adjacent the inside surface 46 thereof.
  • the magnets 50, 52 54, 56, and 58 are secured to conductive support plates 60, 62, and 64 which act as pole pieces and are in turn secured to a series of plates 66 (one shown) mounted on the shaft 42.
  • One of the bearing members 43 extends through the end face of the cylinder exposing a shaft portion through which the drive mechanism (not shown) is connected for driving the cylinder 40. As the cylinder rotates on the bearing members 43 and the shaft 42 and the assembly 44 remain stationary.
  • a dispenser unit identified generally as 70 which contains the material for replacing the powder that is removed during the course of development.
  • the dispenser unit 70 is spaced apart from the rotating cylinder providing a spillway 72 through which the developer mix falls as it departs from the surface of the cylinder 40 when the cylinder surface moves out of the magnetic flux field.
  • a collection hopper 74 made up of two chambers 76 and 77, each equipped with rotating augers and 82.
  • the material falling off the surface of the cylinder 40 is deposited in the chamber 76 and is carried in a direction transverse the movement of the cylinder into the chamber 77.
  • the chambers 76 and 77 are separated by a wall 78 that extends longitudinally between the augers 80 and 82.
  • the floor 86 of the container 71 is sloped so that it converges at the dispensing auger 88 which dispenses the granular mass from one end of the container into the chamber 77 onto the auger 82.
  • the new powder that is added is blended with the used mass as it is conveyed by the auger 82.
  • Centrally located in the container 71 is a mixing blade 90 which gently stirs the granular mass to prevent any caking or agglomeration.
  • the container 71 is closed off with a hinged cover 92 which together with a cover plate 98 serves to enclose a substantial portion of the circumference of the cylinder 40.
  • the auger 82 gently feeds the replenished mass into the V-shaped supply chamber 84 so that the mass accumulates at the bottom of the chamber near the pickup station of the assembly 44.
  • the particles as they leave the magnetic flux pattern generated by the magnetic means 58 leaves the surface of the amass drum 40 and are received on the auger 80. As much as 75 percent of the mass leaving the surface of the drum is returned directly to the supply chamber 84 after receiving some agitation from the auger 80 through ports (not shown) in the wall 78. The remainder of the granular mass is carried into the chamber 77 for replenishment with fresh powder from the container 71, which is dispensed by the auger $8 through openings 99 at the bottom of the container.
  • the operation of the auger may be achieved by a manual control at the option of the operator or it may be associated with an automatic control such as described in US. Pat. No. 3,399,652, issued to Stanley A. Gawron on Sept. 3, 1968.
  • the second magnet 52 generates a flux pattern so as to retain the metered amount of developer mix on the surface of the cylinder.
  • the granular mass that adheres to the surface of the drum at the pickup zone is flattened against the surface due to the flux pattern passing through the magnetically conductive iron particles as the major constituent of the developer mix.
  • the magnet 56 is mounted with its poles arranged opposite to the magnet 54 so that the north pole is in contact with the pole piece 664.
  • the gaussian rating of the magnet ss at the developing station is in the range of 400-600 units. This produces a weaker magnetic field than the magnets in the zones lltlll and 1104 since it is desirable to produce a brush formation that is erect, closely formed and yet sufficiently soft so that it does not abrade the surface of the photoelectrostatic member. As the surface of the cylinder, with it granular mass enters the field in zone 106 the brush becomes upstanding following the converging lines of magnetic flux into the magnet 56 so that as it passes through the developing station 116 it sweeps across the surface of the sheet.
  • zone H08 From the developing station 16 (FIG. 11) and beyond zone 106 the cylinder carrying the granular mass moves to zone H08 where it is continued to be held by a more strong magnet, having in the range of 500-700 gauss units, and thereby assuring a strong retention of the granular mass against the surface of the cylinder, but not in a manner which is related to a brush formation.
  • the pole piece 641 terminates at the magnet having a leg portion 107 extending upward shielding the free end of magnet 58 so that the flux field generated in zone b terminates in an abrupt pattern.
  • the granular mass beyond the station 1108 will fall away from the surface of the cylinder d0 since it is no longer under the influence of a magnetic flux field and falls through the spillway '72 by force of gravity.
  • the zone 1-113 serves a discharging function moving the granular mass in the direction of the spillwuy 72.
  • the magnetic flux generating assembly is identified generally as ll Ml.
  • the magnetic assembly is disposed inside the cylinder Ill ti the latter being rotatably mounted on a fixed shaft .lllt'l.
  • Aft'ixed to the shaft is the flux generating assembly i1 1, which includes an array of individual magnets T20, T22, T24, 3126, T28, 130, and M12.
  • the magnets are mounted on pole pieces Ti t M0, and lt-Il. which in turn are secured to a series of plates ll l l (one shown) axially mounted on the shaft 1 18 to that the magnetic flux generating assembly remains stationary with respect to the rotating cylinder 31b.
  • the cylinder is driven through the shaft extension of the bearing member Mo which engages the shaft M8.
  • the array of magnets juxtaposed the inside surface ll? of the cylinder results in the creation of a series of zones through which the surface of the cylinder passes as it rotates.
  • Magnets T20 and T22 mounted on pole piece T30 form a first zone l4?) at which the mass of developer mix is picked up or attracted to the surface of the cylinder.
  • the granular mass attracted to the cylinder passes through the exitway E02 in lFlG. ll.
  • the mass is held by virtue of the lines of magnetic flux emanating from the magnets 1 .20, 122 and which are overlapped by the magnetic flux generated from the magnet i2 3 attached to the pole piece M0 which is the transport zone M9.
  • the third zone 152 is the developing zone formed by the magnets 11%, llifit] and secured at the north poles of each magnet to the pole piece 1140.
  • the south pole of the magnet faces in the direction of the inside surface ill? of the cylinder lid.
  • the developer mix accumulated and held on the surface of the cylinder moves into the developing zone i532. it follows the converging lines of force entering magnet i215 becoming upstanding in a bristlelike formation 152A.
  • the bristlelilie formation becomes flattened moving in a direction of rotation.
  • the latent image bearing sheet of electrostatic paper receives its first sweep by the brush formation llfiZA formed opposite the magnet P126.
  • the multiple magnet location in the developing zone as contrasted to the magnet array in zone T06 of H6. 2 greatly increases the area of available brush formation for developing and contacting a corresponding area on the photoconductive layer as it passes through the developing zone. This has the net affect of providing multiple development of the sheet in contrast to the development achieved in FIG. Ii.
  • Such multiple brush formation is of particular importance in a high-speed developing machine where it is critical that the fast moving photoconductive member with its charged image on the surface is brushed with as great a volume of electroscopic powder as possible in order to greatly increase the probability of attraction of the material to the image resulting in increased image density.
  • the flux pattern generated by magnet 132 forms the discharge station 154 which returns the developer mix to the dispenser unit.
  • FIG. 3 may be readily substituted for the array in FIG. 1.
  • thermoplastic toner particles in the range of -40 carrier particles to one particle of toner.
  • a charge of thermoplastic powder which is gently agitated by the blade 90.
  • the brush formation that is formed at zone 106 is brought into the next zone 108 where it is again firmly held in a somewhat flat tened condition by the high-intensity magnet 58 so that the mass is then discharged into the spillway 72 where the magnetic flux pattern terminates at magnet 58.
  • the granular mass falls into the chamber 76 where it is picked up by the auger 80 and moved longitudinally along the length of the cylinder where it is picked up by the auger 82 and moved through the chamber 77.
  • thermoplastic powder that has been removed in the developing station 16 is replenished from the dispenser unit 70 by the action of the auger 88 which dispenses incremental quantities of the toner into the chamber 77 where it is intermixed by the auger 82 with the retum developer mix. From chamber 77, where the replenished toner is thoroughly intermixed with the existing developer mix it is returned to the chamber 84 and the cycle is repeated.
  • the chamber 84 is sloped in the direction of the exitway 102 so that the developer mix accumulates in the area immediately opposite the zone 100. This obviates the need for any physical movement or compression of the developer mix in the direction of the cylinder avoiding any compaction or agglomeration of the thermoplastic materials. Further, the magnets at the zone 100 attracts substantial quantities of the developer mix from the supply station so that through the use of the magnets the quantity of material is picked up and held on the drum and transported to the developing station.
  • the entire cylinder is enclosed by the elements 34 and 94, dispenser unit 70, supply unit 74, and the cover plate 110, so
  • the aforedescribed arrangement substantially reduces the opportunities wherein the developer mix is exposed to comminution forces.
  • the granular mass falls down the spillway it is received into the chamber 76 and is generally moved away from the working area by the auger 80.
  • the chambers 76 and 77 are separated by the wall 78 so that the redistribution of replenished material into the developer mix proceeds independently of the materials falling through the spillway 72.
  • the accumulation of any developer mix in the space between the cylinder 40 and the guide plate is minimized by doctoring the surface of granular mass as it leaves the supply station 84.
  • One of the important advantages of terminating the magnetic flux pattern at station 108 is that it provides a large segment of the perimeter of the cylinder free of flux so that the granular material no longer adheres. This is particularly effective when using a cylinder made of a nonconductive material such as a plastic, obviating the need for any scraping means which would tend to remove any adhering developer mix from the surface and thus eliminates the need for an instrument which tends to grind the particles.
  • a magnetic brush assembly for a brush developer adapted to develop electrostatic images carried on a sheet material at high-speed comprising:
  • an applicator drum comprising a rotatable hollow cylinder having a fixed magnetic flux generating assembly disposed adjacent the inside surface of the cylinder for attracting and releasably retaining a mass of developer mix on the surface thereof,
  • a supply station for supplying developer mix juxtaposed a portion of the outer surface of the cylinder
  • a developing station having ingress and egress means for said sheet material and feeding said sheet material immediately adjacent the cylinder
  • mixing means disposed between said supply and collecting stations for mixing the developer mix and feeding it from the collecting station to the supply station,
  • said magnetic flux generating assembly including a series of radially spaced magnet means with said cylinder creating at least four distinct developer mix handling zones extending along the path of rotation of the cylinder from a point adjacent the supply station to a point beyond the developing station, a first zone being located adjacent the supply stationfor picking up a mass of developer mix, a second zone being located adjacent the developer station for causing the developer mass to become upstanding on the cylinder surface, a third zone for conveying the mass between said first and second zones, and a fourth zone for conveying the developer mass away from the developing station toward the collecting station, the strength of the magnetic field in the second zone where the developer mass becomes upstanding on the cylinder surface being low compared to other of the zones so as to reduce abrasion of the sheet material during developing.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Magnetic Brush Developing In Electrophotography (AREA)
  • Dry Development In Electrophotography (AREA)
US9316A 1970-02-06 1970-02-06 High-speed magnetic brush developer apparatus Expired - Lifetime US3626898A (en)

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Application Number Priority Date Filing Date Title
US931670A 1970-02-06 1970-02-06

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US9316A Expired - Lifetime US3626898A (en) 1970-02-06 1970-02-06 High-speed magnetic brush developer apparatus

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US (1) US3626898A (enExample)
JP (1) JPS5035415B1 (enExample)
BE (1) BE762571A (enExample)
CA (1) CA939138A (enExample)
FR (1) FR2078201A5 (enExample)
GB (1) GB1342824A (enExample)
NL (1) NL7101571A (enExample)

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3754526A (en) * 1971-12-17 1973-08-28 Ibm Electrophotographic development apparatus
US3783828A (en) * 1971-08-16 1974-01-08 Zellweger Uster Ag Apparatus for developing latent electrostatic charge images
US3883240A (en) * 1970-03-11 1975-05-13 Canon Kk Electrophotographic copying machine
US3939801A (en) * 1973-09-10 1976-02-24 Minolta Camera Kabushiki Kaisha Magnetic brush developing apparatus
US3945343A (en) * 1975-03-24 1976-03-23 General Electric Company Magnetic brush for use in magnetic printing
US3947107A (en) * 1974-11-20 1976-03-30 Xerox Corporation Partially submerged active crossmixer
DE2545494A1 (de) * 1974-10-10 1976-04-22 Canon Kk Entwicklungseinrichtung
US3952701A (en) * 1974-11-05 1976-04-27 Hitachi Metals, Ltd. Electrostatic developing apparatus
US3988816A (en) * 1974-10-23 1976-11-02 Tdk Electronics Company, Limited Magnet roller for electrostatic record developing device
US4040387A (en) * 1972-09-24 1977-08-09 Mita Industrial Co. Ltd. Electrostatic photographic copying apparatus
US4048958A (en) * 1976-03-08 1977-09-20 Fuji Xerox Co., Ltd. Magnetic brush developing device
US4091765A (en) * 1977-02-17 1978-05-30 Vivian L. Lowthorp, Executrix of the Estate of Ernest C. Lowthorp, deceased Developing and fusing apparatus
US4143961A (en) * 1974-04-15 1979-03-13 Hiroo Nakamoto Electrophotographic duplication apparatus
US4267796A (en) * 1978-04-28 1981-05-19 Konishiroku Photo Industry Co., Ltd. Apparatus for developing electrostatic latent image
US4555172A (en) * 1981-07-10 1985-11-26 Konishiroku Photo Industry Co., Ltd. Developing apparatus
US5052336A (en) * 1989-08-26 1991-10-01 Ricoh Company, Ltd. Developing roller for a developing unit with transport, develop and collect magnets
US5280323A (en) * 1991-09-10 1994-01-18 Xerox Corporation Development apparatus employing magnetic field shapers

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62106932U (enExample) * 1985-12-24 1987-07-08
US10948534B2 (en) 2017-08-28 2021-03-16 Teradyne, Inc. Automated test system employing robotics

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3387586A (en) * 1966-06-06 1968-06-11 Addressograph Multigraph Magnetic developer apparatus
US3402698A (en) * 1966-06-06 1968-09-24 Konishiroku Photo Ind Magnet assembly for magnetic developing brush and developing apparatus for electrostatic process
US3457900A (en) * 1968-02-29 1969-07-29 Eastman Kodak Co Single magnetic brush apparatus for development of electrostatic images
US3523518A (en) * 1964-11-20 1970-08-11 Old Town Corp Developer power replenishment means

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3145122A (en) * 1962-08-13 1964-08-18 Addressograph Multigraph Apparatus for applying developer powder to photo-conductive insulating material
JPS401348Y1 (enExample) * 1964-09-22 1965-01-16

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3523518A (en) * 1964-11-20 1970-08-11 Old Town Corp Developer power replenishment means
US3387586A (en) * 1966-06-06 1968-06-11 Addressograph Multigraph Magnetic developer apparatus
US3402698A (en) * 1966-06-06 1968-09-24 Konishiroku Photo Ind Magnet assembly for magnetic developing brush and developing apparatus for electrostatic process
US3457900A (en) * 1968-02-29 1969-07-29 Eastman Kodak Co Single magnetic brush apparatus for development of electrostatic images

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3883240A (en) * 1970-03-11 1975-05-13 Canon Kk Electrophotographic copying machine
US3783828A (en) * 1971-08-16 1974-01-08 Zellweger Uster Ag Apparatus for developing latent electrostatic charge images
US3754526A (en) * 1971-12-17 1973-08-28 Ibm Electrophotographic development apparatus
US4040387A (en) * 1972-09-24 1977-08-09 Mita Industrial Co. Ltd. Electrostatic photographic copying apparatus
US3939801A (en) * 1973-09-10 1976-02-24 Minolta Camera Kabushiki Kaisha Magnetic brush developing apparatus
US4143961A (en) * 1974-04-15 1979-03-13 Hiroo Nakamoto Electrophotographic duplication apparatus
DE2545494A1 (de) * 1974-10-10 1976-04-22 Canon Kk Entwicklungseinrichtung
US3988816A (en) * 1974-10-23 1976-11-02 Tdk Electronics Company, Limited Magnet roller for electrostatic record developing device
US3952701A (en) * 1974-11-05 1976-04-27 Hitachi Metals, Ltd. Electrostatic developing apparatus
US3947107A (en) * 1974-11-20 1976-03-30 Xerox Corporation Partially submerged active crossmixer
DE2551985A1 (de) * 1974-11-20 1976-05-26 Xerox Corp Entwicklungsvorrichtung
US3945343A (en) * 1975-03-24 1976-03-23 General Electric Company Magnetic brush for use in magnetic printing
US4048958A (en) * 1976-03-08 1977-09-20 Fuji Xerox Co., Ltd. Magnetic brush developing device
US4091765A (en) * 1977-02-17 1978-05-30 Vivian L. Lowthorp, Executrix of the Estate of Ernest C. Lowthorp, deceased Developing and fusing apparatus
US4267796A (en) * 1978-04-28 1981-05-19 Konishiroku Photo Industry Co., Ltd. Apparatus for developing electrostatic latent image
US4555172A (en) * 1981-07-10 1985-11-26 Konishiroku Photo Industry Co., Ltd. Developing apparatus
US5052336A (en) * 1989-08-26 1991-10-01 Ricoh Company, Ltd. Developing roller for a developing unit with transport, develop and collect magnets
US5280323A (en) * 1991-09-10 1994-01-18 Xerox Corporation Development apparatus employing magnetic field shapers

Also Published As

Publication number Publication date
GB1342824A (en) 1974-01-03
CA939138A (en) 1974-01-01
JPS5035415B1 (enExample) 1975-11-15
FR2078201A5 (enExample) 1971-11-05
BE762571A (fr) 1971-07-16
NL7101571A (enExample) 1971-08-10

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