US3584601A - Magnetic brush belt development - Google Patents

Magnetic brush belt development Download PDF

Info

Publication number
US3584601A
US3584601A US771219A US3584601DA US3584601A US 3584601 A US3584601 A US 3584601A US 771219 A US771219 A US 771219A US 3584601D A US3584601D A US 3584601DA US 3584601 A US3584601 A US 3584601A
Authority
US
United States
Prior art keywords
magnetic
shield
developer
field producing
move
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
US771219A
Other languages
English (en)
Inventor
Lyman H Turner
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 US3584601A publication Critical patent/US3584601A/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
    • G03G15/09—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer using magnetic brush

Definitions

  • ABSTRACT Xerographic apparatus for the magnetic brush development of latent electrostatic images with a two-component magnetic developer.
  • the apparatus includes a nonmagnetic shield with a roughened face spaced from a parallel stretch of photoconductive material in a xerographic development zone.
  • a rotatable array of spaced magnets is moved on the side of the plate remote from the photoconductor to move developer in brushing contact with the latent electrostatic image being developed.
  • the magnetic array has alternating north and south faces extending transverse to the direction of movement of the magnets so that the developer alternately collapses and reforms during movement of the magnets to thereby move the developer in a direction opposite to the direction of movement of the magnets to develop images in the photoreceptor.
  • a xerographic surface comprising a layer of photoconductive insulating material affixed to a conductive backing is used to support electrostatic images.
  • the xerographic plate is electrostatically charged uniformly over its surface and then exposed to a light pattern of the image being reproduced to thereby discharge charge in the areas where light strikes the layer.
  • the undischarged areas of the layer thus form an electrostatic charge pattern in conformity with the configuration of the original light pattern.
  • the latent electrostatic image can then be developed by contacting it with a finely divided electrostatically attractable material such as a resinous powder.
  • a finely divided electrostatically attractable material such as a resinous powder.
  • the powder is held in image areas by the electrostatic fields on the layer. Where the field is greatest, the greatest amount of material is deposited; and where the field is least, little or no material is deposited.
  • a powder image is produced in conformity with thelight image or of the copy being reproduced.
  • the powder is subsequently transferred to a sheet of paper or other surface and suitably affixed to thereby form a permanent print.
  • the electrostatically attractable developing material commonly used in xerography consists of a pigmented resinous powder referred to here as toner and a carrier" of larger granular beads formed with glass, sand or steel cores located with a material removed in the triboelectric series from the toner so that a triboelectric charge is generated between the toner powder and the granular carrier. Such charge causes the toner to adhere to the carrier.
  • the carrier also provides mechanical control so that the toner can be readily handled and brought into contact with the exposed xerographic surface. The toner is then attracted to the electrostatic image from the carrier to produce a visible powder image on the xerographic surface.
  • the carrier employed is magnetic in nature, that is, it responds when placed in a magnetic field to form a brushlike array with bristles corresponding to the magnetic lines of the field producing means.
  • the carrier employed is magnetic in nature, that is, it responds when placed in a magnetic field to form a brushlike array with bristles corresponding to the magnetic lines of the field producing means.
  • movement of the magnet adjacent the latent electrostatic image may move the entrained developer across the image to deposit the charged toner in a configuration corresponding'to the image being developed. This occurs because the charge on image area portions of the photoconductor exceeds the electrostatic attraction of the carrier coating for the oppositely charged toner.
  • Typical of magnetic brush development systems employed today is that disclosed in U.S. Pat. No. 3,003,462 to Streich. According to that disclosure, a cylinder, formed with magnetic washers having alternate north and south poles, is positioned adjacent the surface being developed. The lower portion of the magnetic cylinder is in contact with a reservoir or sump of magnetic developer material while the upper portion of the magnetic cylinder is located adjacent the latent electrostatic image-bearing surface. When the magnetic cylinder is rotated and the image being developed is moved across the cylinder, magnetic bristles are formed on the surface of the cylinder which contact the image-bearing surface for its development.
  • Other types of magnetic brush development systems are those disclosed in U.S. Pat. No. 2,975,758 to Bird and U.S. Pat. No. 2,874,063 to Greig.
  • each of these prior art systems a magnetic brush is formed under the influence of a magnetic field producing means. Movement-of the magnetic field producing means causes concurrent movement of the brush of magnetic developer. Consequently, that portion of the magnetic developer near the base of the bristle of the brush, adjacent the magnetic producing means is never employed for development since that portion of developer never contacts the photoconductor. Furthermore, each of the prior art systems employs a single extended bristle contacting the image-bearing surface along a small line portion of the xerographic surface transverse to their direction of relative movement.
  • the magnetic brush development apparatus of the instant invention is adapted to form a magnetic brush with many bristles extending over a large surface area whereby image developing material may be contacted to a large surface area of a photoconductive surface. This increases the time and area of the xerographic surface being developed to increase development speed. Furthermore, the apparatus of the instant invention is designed so that the natural movement of themagnetic field producing means will cause a constant erection and disruption of the magnetic bristles so that the entire mass of two-component developer in the brush may be employed for developing images. This feature insures that freshly toned developer will be contacting the xerographic surface along its path of movement. 7
  • lt is a further object of the instant invention to cause turbulence within image developing magnetic brushes for the presentation of fresh developer within the image developing zone.
  • [t is a further object of the instant invention to disrupt and reform magnetic brushes during the development of images.
  • xerographic development apparatus including a shield having a flat portion positioned in spaced relationship from a parallel stretch of photoconductive material in a xerographic development zone.
  • the shield has a roughened surface facing the photoconductor.
  • a cylindrically shaped rotatable array of magnets having a flat stretch corresponding to the photoreceptor is movable on the side of the plate remote from the photoconductor to move developer in brushing contact with the image being developed.
  • the magnetic array has alternating north and south faces extending transverse to the direction of movement of the magnets and photoconductor so that the developer alternately collapses and reforms during movement of the magnets to thereby move the developer in a direction opposite to the direction of movement of the magnets.
  • FIG. 1 is a diagrammatic sectional view illustrating a xerographic reproducing machine adapted for continuous and automatic use and which employs the magnetic brush development apparatus of the instant invention
  • FIG. 2 is an enlarged perspective showing of the magnetic brush development apparatus shown in FIG. 1 with parts broken away for clarity.
  • FIG. 1 Shown in FIG. 1 is a xerographic machine employing the magnetic brush development apparatus of the instant invention.
  • the elements of this machine which are constructed for continuous and automatic operation, are all conventional in the xerographic art except for the novel development apparatus, which forms the basis of the instant application.
  • the several xerographic processing stations in the path of movement of the xerographic surface may be briefly described as follows:
  • a charging station A at which a uniform electrostatic charge is deposited on the photoconductive layer of the xerographic surface
  • An exposure station B at which the light or radiation pattern of copy to be reproduced is projected onto the xerographic surface to dissipate the charge in the exposed areas thereof to thereby leave a latent electrostatic image of the copy to be reproduced:
  • a developing station C at which a xerographic developing material, including toner particles having an electrostatic charge opposite to that of the electrostatic latent image, are moved into contact with the image bearing surface whereby the toner particles adhere to the electrostatic latent image to form a xerographic powdered image in the configuration of the copy being reproduced;
  • a transfer station D at which the xerographic powder image is electrostatically transferred from the xerographic surface to a transfer material or a support surface;
  • a cleaning and discharge station E at which the xerographic surface is brushed to remove residual toner particles remaining thereon after image transfer, and at which the surface is exposed to a relatively bright light source to effect substantially complete discharge of any residual electrostatic charge remaining thereon.
  • the latent electrostatic images to be developed are formed on a xerographic surface formed in the shape of an endless belt.
  • the belt is adapted to be rotated about three supporting rollers l2, l4 and 16, two of which, 12 and M, are idler rollers and the third of which, 16, is a power imparting roller driven by any convenient power source 13.
  • the movement of the xerographic belt permits its surface to be moved past the various xerographic processing stations including the development zone C.
  • the xerographic developing apparatus is provided within a developer housing formed of a nonmagnetic material such as of metal, plastic or the like.
  • the lower portion of the housing is troughlike in configuration to define a sump 22 to support a quantity of magnetic developer.
  • the developer employed includes image developing toner particles and larger carrier granules having magnetic properties.
  • the carrier granules may be metallic or other materials having magnetic properties either uncoated or coated with a carrier coating material so that a triboelectric charge is generated between it and the toner upon mutual interaction. This charge is necessary to effect the xerographic development of the images. Examples of such developers are described in US. Pat. No. 2,874,063 to Greig. Although developer is generally two-component, it could readily be formed of one-component magnetic toner.
  • the housing is supported on its sides by support members 2d which are part of the xerographic reproducing machine and are spaced a distance which is large than the width ofthe photoconductor.
  • bearings for supporting shafts upon which the magnet driving rollers 26, 28 and 30 are supported.
  • Two of these rollers 26 and 28 may be idler rollers while the third 30, is a power driven member positively driven by power source 32. If desired, one of the idler rollers may be spring biased to provide tension within the magnetic assembly.
  • Endless belts 34 are mounted on the rollers for rotation therewith.
  • the belts 34 could readily be formed on any cross-sectional configuration as could the xerographic surface 10.
  • the surface of the belts support the magnetic members 36 in their proper orientation with respect to each other and with respect to the photoconductive surface to be developed.
  • the magnets may be glued or otherwise attached to the belts. Each of the magnets extends the full width of the photoconductor surface of the xerographic belt.
  • the magnets are placed with alternating north and south faces extending transverse to the direction of their movement with spacings 38 therebetween for a purpose to be later described.
  • This shield extends from an area to extend between rollers 26 and 30. It also has an extension portion Mi so that magnetic developer passed above roller 26 will be directed beyond the magnetic field of magnets 36 and cascade down the extension portion 44 for being redeposited in the sump 22 for recirculation by the magnetic belt assembly.
  • the exterior surface 46 of the shield facing the photoreceptor is slightly roughened within the development zone as by etching or sandblasting so that movement of developer therealong, us caused by the movement of the magnets, will prohibit a smooth sliding on the bristles of the magnetic brushes along the shield within the development zone.
  • roller 30 is driven by power source 32 to rotate on its axis in a counterclockwise direction, as viewed in FIGS. 1 and 2 causing the endless belts 34 and magnets 36 to move downwardly from roll 26 to and around roll 30, upwardly to and around roll 28, and then to and around roll 26.
  • This action will be continually carried on during development of an image while the image supporting photoconductive belt is moved in a counterclockwise direction by power source 18 in a direction of the arrow as shown in the arrow in FIGS. 1 and 2.
  • magnetic lines of force extend from the faces of the magnets through the flat portion of the shield at 42. These force lines are substantially at right angles to the faces of the magnets in a relatively wide area at the center of the magnets extending at least to the photoreceptor.
  • the lines of force gradually incline toward the adjacent magnets when adjacent the edges thereof until the force field at the edge of the magnets is substantially parallel to their faces across spaces 38. Very good results were attained when the spaces between the magnets were slightly less than half the cross-sectional lengths of the magnets.
  • the roughened surface 46 of the shield prevents the developer mix from smoothly sliding thereon under the influence of the moving magnetic force lines.
  • the bristles adjacent the magnetic force lines corresponding to the approximate center areas of the magnet will first incline toward the next approaching magnet and then collapse in a loose mass under the varying position of the magnetic field producing means.
  • the mass of loose developer mixture in the areas corresponding to the spaces between the magnets will now be influenced by the lines of force from the center of the approaching magnet and will be erected as new bristles.
  • the alternating erection and collapse of the whiskers in end-overend fashion causes the entire mass of developer mixture on the surface of the enclosure to be moved in a tumbling manner in a direction opposite to the direction of movement of the magnets.
  • the developer mixture moves to that portion of the shield around roll 26 and is removed from the influence of the magnetic lines of force by reason of the shape of the shield in this area, the developer mixture gravity falls down extension 44 to the sump for remixing with the developer already there. in this manner, it is ready for recirculation under the influence of the magnets for reuse in developing images on the xerographic surface in a continuous fashion.
  • a toner dispenser 50 Positioned adjacent this portion of the developer housing is a toner dispenser 50 for the addition of supplemental toner particles for replacing that toner lost from the mixture due to the development of images.
  • the shield is held in position within the housing so as to be closely spaced from the surface being developed. This distance should be substantially equal throughout the mutual extents of the flat portion of the shield and photoconductor at a distance slightly less than the average length of the bristles of the magnetic brush so that the tips of the brushes will contact the surface of the image bearing photoconductor. As the tips of the brushes move over the xerographic surface, toner particles are transferred to image area portions of the photoconductor from the developer mix since the individual toner particles have a greater electrostatic attraction for the high charge on the image areas than the relatively low charge on the associated carrier granules.
  • each bristle of the magnetic brushes into a loose mass will occur through the movement of the magnets after the tip of each brush has contacted the xerographic surface and thus different alignments of the developer mixture will present different portions of the different portions of the developer mixture to the photoconductor upon reerection of the developer.
  • each magnetic brushing of the surface of the photoconductor member will present the maximum available toner particles for complete development of the latent electrostatic image. Beyond this, the extended length of the development zone insures complete development of the images.
  • Apparatus for developing latent electrostatic images on a photoconductive surface with magnetic developer including rotatable endless belt means having magnetic field producing means on the surface thereof arranged with spaced north and south faces extending across the periphery of the belt means to define nonmagnetic spacings therebetween, means to .support said rotatable endless belt means in spaced relation from a photoconductive surface to be developed at a distance less than the distance of the lines of magnetic force emanating from said magnetic field producing means,
  • shield means adjacent said field producing means, positioned between said field producing means and the photoconductive surface, the face of said shield means remote from said magnets being roughened to prevent the smooth sliding of developer material thereacross and means to move said field producing means in a path of movement relative to said shield means to thereby cause magnetic developer material entrained on the roughened face of said shield means by the magnetic fields there adjacent to move in image developing contact with the photoconductive surface along the roughened face of said shield means in a direction opposite the direction of movement of said field producing means.
  • Apparatus for developing a developable surface of a member supporting latent electrostatic images with magnetic developer including magnetic field producing means including spaced north and south faces supported in closed-loop configuration with a portion thereof being located adjacent a developable surface in a xerographic development zone,
  • shield means supported within the xerographic development zone intermediate the developable surface and said magnetic field producing means, shield means including a surface facing the developable surface capable of preventing the smooth sliding of magnetic developer there across and means to move said magnetic field producing means with respect to said shield means of that developer material entrained on the surface of said shield means will move across said shield means in a direction opposite from the direction of movement of said magnetic field producing means to thereby contact and develop the latent electrostatic images on the developable surface.
  • Apparatus for developing the developable surface of a member supporting latent electrostatic images with magnetic developer including first means adapted to create magnetic fields including spaced north and south faces supported for at least a portion of their extent adjacent a developable surface in a xerographic development zone,
  • second means comprising a shield supported within the xerographic development zone intermediate the developable surface and said first means, said shield including a surface facing and developable surface being adapted to prohibit the smooth sliding of developer thereacross,

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Magnetic Brush Developing In Electrophotography (AREA)
  • Dry Development In Electrophotography (AREA)
US771219A 1968-10-28 1968-10-28 Magnetic brush belt development Expired - Lifetime US3584601A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US77121968A 1968-10-28 1968-10-28

Publications (1)

Publication Number Publication Date
US3584601A true US3584601A (en) 1971-06-15

Family

ID=25091102

Family Applications (1)

Application Number Title Priority Date Filing Date
US771219A Expired - Lifetime US3584601A (en) 1968-10-28 1968-10-28 Magnetic brush belt development

Country Status (3)

Country Link
US (1) US3584601A (de)
DE (1) DE1953228A1 (de)
GB (1) GB1238277A (de)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3678895A (en) * 1969-03-15 1972-07-25 Ricoh Kk Magnetic cascade development device for dry process electrophotography
US3724422A (en) * 1970-12-14 1973-04-03 Xerox Corp Magnetic brush developing apparatus
US3753420A (en) * 1971-08-11 1973-08-21 Olivetti & Co Spa Magnetic brush developer system
US3921578A (en) * 1972-07-03 1975-11-25 Itek Corp Power cascade electrophotographic development
US4067295A (en) * 1975-03-07 1978-01-10 Xerox Corporation Magnetic microfield donor system
US4156036A (en) * 1976-07-30 1979-05-22 Epp Corp. Structured donor sheet for high-resolution non-impact printer
US4193376A (en) * 1976-11-29 1980-03-18 Sharp Kabushiki Kaisha Developer powder supply in magnet brush development
US4284031A (en) * 1978-08-04 1981-08-18 Sperry Corporation Magnetic transfer surface for controlling toner thickness
US4330193A (en) * 1979-10-01 1982-05-18 Xerox Corporation Development system
US4332457A (en) * 1977-04-22 1982-06-01 Sharp Kabushiki Kaisha Fixing device for fixing images of an original document on plain paper copy sheets
US4352552A (en) * 1980-06-25 1982-10-05 Xerox Corporation Multicolor development system for electrophotographic printing machines
US5826151A (en) * 1997-06-30 1998-10-20 Xerox Corporation Apparatus and method for non interactive agitated magnetic brush development
US5966576A (en) * 1997-07-28 1999-10-12 Eastman Kodak Company Extended development zone apparatus with rotating magnets

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3117891A (en) * 1960-09-26 1964-01-14 Xerox Corp Xerographic apparatus
US3145122A (en) * 1962-08-13 1964-08-18 Addressograph Multigraph Apparatus for applying developer powder to photo-conductive insulating material
US3208296A (en) * 1962-04-26 1965-09-28 Baermann Max Belt drive device
US3455276A (en) * 1967-05-23 1969-07-15 Minnesota Mining & Mfg Magnetically responsive powder applicator
US3457900A (en) * 1968-02-29 1969-07-29 Eastman Kodak Co Single magnetic brush apparatus for development of electrostatic images

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3117891A (en) * 1960-09-26 1964-01-14 Xerox Corp Xerographic apparatus
US3208296A (en) * 1962-04-26 1965-09-28 Baermann Max Belt drive device
US3145122A (en) * 1962-08-13 1964-08-18 Addressograph Multigraph Apparatus for applying developer powder to photo-conductive insulating material
US3455276A (en) * 1967-05-23 1969-07-15 Minnesota Mining & Mfg Magnetically responsive powder applicator
US3457900A (en) * 1968-02-29 1969-07-29 Eastman Kodak Co Single magnetic brush apparatus for development of electrostatic images

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3678895A (en) * 1969-03-15 1972-07-25 Ricoh Kk Magnetic cascade development device for dry process electrophotography
US3724422A (en) * 1970-12-14 1973-04-03 Xerox Corp Magnetic brush developing apparatus
US3753420A (en) * 1971-08-11 1973-08-21 Olivetti & Co Spa Magnetic brush developer system
US3921578A (en) * 1972-07-03 1975-11-25 Itek Corp Power cascade electrophotographic development
US4067295A (en) * 1975-03-07 1978-01-10 Xerox Corporation Magnetic microfield donor system
US4156036A (en) * 1976-07-30 1979-05-22 Epp Corp. Structured donor sheet for high-resolution non-impact printer
US4193376A (en) * 1976-11-29 1980-03-18 Sharp Kabushiki Kaisha Developer powder supply in magnet brush development
US4332457A (en) * 1977-04-22 1982-06-01 Sharp Kabushiki Kaisha Fixing device for fixing images of an original document on plain paper copy sheets
US4284031A (en) * 1978-08-04 1981-08-18 Sperry Corporation Magnetic transfer surface for controlling toner thickness
US4330193A (en) * 1979-10-01 1982-05-18 Xerox Corporation Development system
US4352552A (en) * 1980-06-25 1982-10-05 Xerox Corporation Multicolor development system for electrophotographic printing machines
US5826151A (en) * 1997-06-30 1998-10-20 Xerox Corporation Apparatus and method for non interactive agitated magnetic brush development
US5966576A (en) * 1997-07-28 1999-10-12 Eastman Kodak Company Extended development zone apparatus with rotating magnets

Also Published As

Publication number Publication date
DE1953228A1 (de) 1970-05-06
GB1238277A (de) 1971-07-07

Similar Documents

Publication Publication Date Title
US4034709A (en) Developer roll
US3457900A (en) Single magnetic brush apparatus for development of electrostatic images
US4194830A (en) Development apparatus
US3572288A (en) Development apparatus
US3176652A (en) Xerographic developing apparatus
US2832311A (en) Apparatus for development of electrostatic images
US3552355A (en) Development apparatus
US3641980A (en) Development apparatus
US3584601A (en) Magnetic brush belt development
US3638614A (en) Electrostatic latent image development apparatus
US3572289A (en) Magnetic brush development apparatus
US4098228A (en) High speed magnetic brush development system
US3412710A (en) Cleanup electrode
US3416494A (en) Xerographic development electrode
US2975758A (en) Apparatus for developing electrostatic images
GB2074903A (en) Developing latent images
US3911864A (en) Toner preloaded magnetic brush development system
US3662711A (en) Development apparatus
US3894513A (en) Copying machine with bead pickoff roller
US3415224A (en) Magnetic cascade development apparatus
EP0120688B1 (de) Entwicklungssystem unter Verwendung einer dünnen Schicht von Markierungsteilchen
US3380437A (en) Transversely reciprocating fluidized bed development apparatus
US3592166A (en) Apparatus for developing electrostatic images
US3484265A (en) Transversely reciprocating fluidized bed development method
US3542466A (en) Development apparatus