US3908595A - Magnetic brush development apparatus utilizing magnetic means - Google Patents

Magnetic brush development apparatus utilizing magnetic means Download PDF

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Publication number
US3908595A
US3908595A US436713A US43671374A US3908595A US 3908595 A US3908595 A US 3908595A US 436713 A US436713 A US 436713A US 43671374 A US43671374 A US 43671374A US 3908595 A US3908595 A US 3908595A
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United States
Prior art keywords
magnetic
latent image
moving
longitudinal axis
magnet
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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US436713A
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English (en)
Inventor
Ryuzo Okada
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.)
Fujifilm Business Innovation Corp
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Fuji Xerox Co Ltd
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Publication date
Application filed by Fuji Xerox Co Ltd filed Critical Fuji Xerox Co Ltd
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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

Definitions

  • ABSTRACT Magnetic brush developing apparatus for developing a latent image on a moving insulating layer with magnetic developer, the apparatus comprising first mag- 1 1 Sept.
  • netic means having a longitudinal axis extending substantially parallel to the moving, latent image bearing layer and substantially transverse to the direction of movement thereof, the first magnetic means having only one plane of polarization which is directed substantially transverse both to the longitudinal axis and the moving, latent image bearing layer to produce a first magnetic field at the layer, means for moving the magnetic developer through the first magnetic field to initiate development of the latent image, second magnetic means having a longitudinal axis extending substantially parallel to the moving, latent image bearing layer and substantially transverse to the direction of movement thereof, the second magnetic means being subsequent to the first magnetic means along the direction of movement of the image bearing layer and being polarized at a plurality of predetermined angles about the longitudinal axis where, at each angle, the second magnetic means is polarized in a direction substantiallly transverse to the longitudinal axis to thereby produce a plurality of magnetic fields at the layer, means for transferring the magnetic developer from the first magnetic field produced by the first magnetic means to the plurality of magnetic fields produced by the second magnetic means to continue and complete
  • FIG. I PRIOR ART
  • FIG. 2
  • This invention relates to a developing apparatus in a copying machine, and more particularly to magnetic brush developing apparatus using a plurality of magnetic brush rolls in a dry type high-speed copying machine.
  • the peripheral speed of the photosensitive plate is increased with increased copying speed.
  • the peripheral speed of the magnetic brush rolls is increased too much, the developer powder is blown off the periphery of each roll by centrifugal force or it slips on the roll surfaces.
  • scattering of the toner particles into the air is promoted thus soiling the background portion of the copying paper or the inside of the copying machine. Therefore, to alleviate this problem and to obtain reproductions with high image quality, it has been necessary to use a plurality of magnetic brush rolls disposed along the periphery of the plate to keep the peripheral speed of each roll below a certain level,
  • each of the magnetic brush rolls comprises a magnet fixed with a certain orientation and a cylindrical body rotatably disposed around the magnet.
  • the magnets used in such magnetic brush rolls may be roughly divided into the following two types in terms of shape.
  • One type is the rectangular prismatic magnets which have a magnetization pattern directed toward the sensi tive plate, and the other type is the cylindrical or columnar magnets which are magnetized to provide more than two poles on the magnet surface.
  • each magnet provides magnetism on both the front and back sides so that the magnetic lines of force at both ends of each magnet are directed opposite to that of the circular field in the middle of the magnet. That is, magnetic lines of force at the ends present a pattern such as indicated by a in FIG. 1 and these tend to be oppositely directed to those at the middle of the magnet.
  • the image density at the end areas of each magnet is lower than the density in the middle portion thereof.
  • a primary purpose of the present invention is to provide an improved developing apparatus in a copying machine where the aforementioned problems of the prior art are overcome.
  • FIG. 1 is a diagrammatic illustration of a pattern of magnetic lines of force produced by a rectangular prismatic magnet.
  • FIG, 2 is a schematic drawing of an illustrative embodiment of the present invention.
  • FIG. 3 is a sectional view taken along the line III-lII of FIG. 2.
  • a sensitive drum 1 is illustrated, the surface of which is subjected to electric charging and exposure by a method generally known as the xerography process, so as to form thereon electrostatic latent images.
  • a developing mechanism 2 is provided in opposition to the surface of the sensitive drum 1 for developing the electrostatic latent images on the drum surface.
  • Developing mechanism 2 comprises three magnetic brush developing rolls 3, 4 and 5, a toner distributor 6, a developer guide plate 7, a developer stirring means 8, and a developer flow rate regulator plate 9.
  • Each of the magnetic brush developing rolls 3, 4 and 5 includes at least one magnet (which are described in more detail below) and a preferably non-magnetic cylinder disposed for clockwise rotation about its associated magnet or magnets.
  • a pair of rectangular prismatic magnets 13 and 14 are fixedly disposed in rotatable cylinder 10 of magnetic brush developing roll 3, and cylindrical magnets 15 and 16 are respectively fixedly disposed in rotatable cylinders 11 and 12 of rolls 4 and 5, and these magnets are secured to fixed rods 17, 18 and 19, respectively.
  • the developer is supplied from a space between the cylinder 10 of the lowermost magnetic brush developing roll 3 and the developer flow rate regulator plate 9 by the attraction of magnets 13 and 14 for the developer and is moved forward in the magnetic field of these magnets with rotation of cylinder 10 to initiate development of the latent image on drum 1. It is subsequently transferred to rolls 4 and 5 as image development continues.
  • the used developer separates from the topmost magnetic brush developing roll 5 and flows down over developer guide plate 7.
  • the used developer with reduced toner content is replenished with toner from toner distributor 6.
  • the toner-replenished developer falls through double-layer de veloper stirring means 8.
  • One of the layers in stirring means 8 moves the developer forwardly in FIG. 2 and the other layer moves it rearwardly in FIG. 2, to thereby provide a uniform toner distribution in the developer and to maintain an optimum pattern of electric charging of both toner and carrier.
  • FIG. 3 is a view along the line lIIIII of FIG. 2.
  • the cylinders l0, l1 and 12 are rotated by their respective driving shafts 20, 21, and 22, and the magnets are secured to the fixed rods l7, l8 and 19, respectively, which are, in turn, secured to a side wall 26 of the housing through securing means 23, 24 and 25, respectively.
  • the broken slant lines in FIG. 3 show the pattern of developer. According to results of experiments, it was confirmed that developer on the magnetic brush developing rolls has the following features. Rise-up of developer is high and a satu rated state of coarse developer is created at part I? in FIG. 3, but such tendency is diminshed in parts L and (I, and that the range of uniform deposition of the developer is relatively narrow at part b and wider at parts c and (I.
  • the developing apparatus comprises magnetic brush developing rolls using cylindrical or columnar magnets and a magnetic brush developing roll using a pair ofjoined rectangular prismatic magnets, the magnets being arranged so that the high rise-up of devel oper caused by the rectangular prismatic magnets will help to reduce non-uniformity of image density caused by deflection of the developing rolls and sensitive plate as is the case in conventional developing systems, while the cylindrical or columnar magnets effect uniform development along the width of the copying paper, thus making it possible to obtain uniform image quality with a relatively simple structure.
  • the present invention has been described by way of a preferred embodiment thereof, it is not limited to this particular embodiment.
  • the direction of rotation of the sensitive plate or the direction of flow of the developer can be selected freely to suit the situation, and hence the additional use of a developer lifting mechanism is involved within the technical scope of the present invention.
  • the number of magnetic brush developing rolls is not limited to three as in the shown embodiment but any number of such rolls, if not smaller than two, can be used as is necessary.
  • Magnetic brush developing apparatus for developing a latent image on a moving insulating layer with magnetic developer, said apparatus comprising a rectangular magnet having a longitudinal axis extending substantially parallel to said moving, latent image bearing layer and substantially transverse to the direction of movement thereof. said rectangular magnet having only one plane of polarization which is directed substantially transverse both to said longitudinal axis and said moving, latent image bearing layer to produce a first magnetic field at said layer;
  • At least one cylindrical magnet having a longitudinal axis extending substantially parallel to said moving. latent image bearing layer and substantially transverse to the direction of movement thereof, said cylindrical magnet being subsequent to said rectangular magnet along the direction of movement of said image bearing layer and being polarized at a plurality of predetermined angles about said longitudinal axis where, at each angle, said cylindrical magnet is polarized in a direction substantially transverse to said longitudinal axis to thereby pro Jerusalem a plurality of magnetic fields at said layer; means for transferring said magnetic developer from said first magnetic field produced by said rectangular magnet to said plurality of magnetic fields produced by said cylindrical magnet to continue and complete the development of said latent image; said cylindrical magnet compensating the tendency of said rectangular magnet to underdevelop the latent image portions adjacent the end portions of the rectangular magnet and said rectangular magnet compensating the tendency of said cylindrical magnet to nonuniformly develop the latent image.
  • both said moving means and said transferring means comprise rotatable, hollow cylinders concentric with said first and second magnetic means respectively.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Magnetic Brush Developing In Electrophotography (AREA)
US436713A 1973-04-05 1974-01-25 Magnetic brush development apparatus utilizing magnetic means Expired - Lifetime US3908595A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP48038232A JPS49126337A (fr) 1973-04-05 1973-04-05

Publications (1)

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US3908595A true US3908595A (en) 1975-09-30

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US436713A Expired - Lifetime US3908595A (en) 1973-04-05 1974-01-25 Magnetic brush development apparatus utilizing magnetic means

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US (1) US3908595A (fr)
JP (1) JPS49126337A (fr)
DE (1) DE2414980C3 (fr)
GB (1) GB1449322A (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3977361A (en) * 1975-05-13 1976-08-31 Fuji Xerox Co., Ltd. Magnetic brush developing device
US3985099A (en) * 1974-05-13 1976-10-12 Fuji Xerox Co., Ltd. Magnetic brush developing device
US4108658A (en) * 1974-03-11 1978-08-22 Oce-Van Der Grinten N.V. Process for developing electrostatic latent images
US4266868A (en) * 1979-07-16 1981-05-12 Minnesota Mining And Manufacturing Company Multiple roll developing apparatus
US5630201A (en) * 1995-03-10 1997-05-13 Hitachi Koki Co., Ltd. Development apparatus having a plurality of rolls rotated at particular speeds
US20130195513A1 (en) * 2012-01-26 2013-08-01 Fuji Xerox Co., Ltd. Developing device and image forming apparatus

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3133834A (en) * 1961-06-22 1964-05-19 Rca Corp Electrostatic developing apparatus
US3152924A (en) * 1961-05-24 1964-10-13 Robertson Photo Mechanix Inc Xerographic brush
US3543720A (en) * 1968-02-29 1970-12-01 Eastman Kodak Co Apparatus for development of electrostatic images
US3640248A (en) * 1969-06-04 1972-02-08 Xerox Corp Electrostatic magnetic developing apparatus
US3724422A (en) * 1970-12-14 1973-04-03 Xerox Corp Magnetic brush developing apparatus

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3152924A (en) * 1961-05-24 1964-10-13 Robertson Photo Mechanix Inc Xerographic brush
US3133834A (en) * 1961-06-22 1964-05-19 Rca Corp Electrostatic developing apparatus
US3543720A (en) * 1968-02-29 1970-12-01 Eastman Kodak Co Apparatus for development of electrostatic images
US3640248A (en) * 1969-06-04 1972-02-08 Xerox Corp Electrostatic magnetic developing apparatus
US3724422A (en) * 1970-12-14 1973-04-03 Xerox Corp Magnetic brush developing apparatus

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4108658A (en) * 1974-03-11 1978-08-22 Oce-Van Der Grinten N.V. Process for developing electrostatic latent images
US3985099A (en) * 1974-05-13 1976-10-12 Fuji Xerox Co., Ltd. Magnetic brush developing device
US3977361A (en) * 1975-05-13 1976-08-31 Fuji Xerox Co., Ltd. Magnetic brush developing device
US4266868A (en) * 1979-07-16 1981-05-12 Minnesota Mining And Manufacturing Company Multiple roll developing apparatus
US5630201A (en) * 1995-03-10 1997-05-13 Hitachi Koki Co., Ltd. Development apparatus having a plurality of rolls rotated at particular speeds
US20130195513A1 (en) * 2012-01-26 2013-08-01 Fuji Xerox Co., Ltd. Developing device and image forming apparatus

Also Published As

Publication number Publication date
DE2414980A1 (de) 1974-10-10
DE2414980B2 (de) 1979-05-10
DE2414980C3 (de) 1980-03-06
JPS49126337A (fr) 1974-12-03
GB1449322A (en) 1976-09-15

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