US3640247A - Magnetic powder applicator - Google Patents

Magnetic powder applicator Download PDF

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Publication number
US3640247A
US3640247A US29330A US3640247DA US3640247A US 3640247 A US3640247 A US 3640247A US 29330 A US29330 A US 29330A US 3640247D A US3640247D A US 3640247DA US 3640247 A US3640247 A US 3640247A
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United States
Prior art keywords
powder
tube
magnetic
nonmagnetic
rotation
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Expired - Lifetime
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US29330A
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English (en)
Inventor
Frederick Percival Mason
Frank Arthur Oakley Waren
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Creed and Co Ltd
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Creed and 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
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G19/00—Processes using magnetic patterns; Apparatus therefor, i.e. magnetography

Definitions

  • MAGNETIC POWDER APPLICATOR [72] Inventors: Frederick Percival Mason, Burgess Hill; Frank Arthur Oakley Pain, Hove, both of England [73] Assignee: Creed & Company Limited, Hollingbury,
  • ABSTRACT A magnetizable powder applicator arrangement in a printing or display apparatus employing for example a magnetizable drum.
  • the powder is attracted to the outer surface of a nonmagnetizable tube which contains therein a rotatable row of bar magnets having like poles adjacent.
  • the divergent flux field set up by the rotating magnets causes the powder to creep along the surface of the tube in a direction opposite the magnet rotation, and onto a ledge of nonmagnetizable material.
  • the ledge is sufficiently close to the drum, yet sufiicient'ly far from the flux field, for the powder to be attracted to the drum surface without disturbing the selective magnetization thereon.
  • SHEET 3 BF 3 lnvenlors FR6DER/CK PfRC/VAZ MASON FRANK ARTHUR OAKLEY NARL'N MAGNETIC POWDER APPLICATOR This invention relates to a method and apparatus for handling magnetic powder.
  • a method of transferring magnetic powder along a nonmagnetic surface is a given direction, comprising repeatedly scanning the surface in the opposite direction with a divergent field of magnetic flux, the arrangement being such as to cause somersaulting of the powder in the given direction.
  • the invention has particular application to magnetic printing and/or display devices.
  • Such devices are well known, and essentially comprise a magnetizable surface, such as the surface of a drum or belt, which is movable relative to a set of recording heads and can be selectively magnetized by the heads in accordance with the matter to be printed or displayed, the surface then being dusted" with magnetic powder which adheres to the magnetized regions, thus forming a powder image.
  • the dusted surface my then be used directly for display of the powder image, or it may be used as a printing element for transferring the image to a further surface such as a paper tape or sheet.
  • the invention provides a magnetic printing and/or display device wherein magnetic powder is transferred along a nonmagnetic surface in a given direction by repeatedly scanning the nonmagnetic surface in the opposite direction with a divergent system of magnetic flux, the arrangement being such as to cause somersaulting of the powder in the given direction.
  • the invention provides a magnetic printing and/or display device comprising apparatus for dusting the movable magnetizable surface of the device with magnetic powder, the apparatus including a convex nonmagnetic surface extending upwardly form a supply of the powder to a substantially horizontal nonmagnetic ledge adjacent the magnetizable surface, and a magnetic rotor disposed behind the nonmagnetic surface and having its axis of rotation parallel thereto for producing at the nonmagnetic surface a system of magnetic flux which is divergent in a plane perpendicular to the axis of rotation, the arrangement being such that rotation of the rotor in a given direction causes a layer of magnetic powder to creep in the opposite direction up the nonmagnetic surface and across the ledge by somersaulting of the powder as the flux field repeatedly scans the nonmagnetic surface.
  • the invention provides a magnetic printing and/or display device comprising apparatus for dusting the movable magnetizable surface of the device with magnetic powder, the apparatus including a substantially horizontal nonmagnetic tube, a magnetic rotor inside the tube whose axis of rotation is parallel with the tube, the rotor producing a system of magnetic flux at the outer surface of the tube which is divergent in a plane perpendicular to the tube axis, and a substantially horizontal nonmagnetic ledge extending substantially tangentially from the outer surface of the tube to adjacent the magnetizable surface, the arrangement being such that rotation of the rotor in a given direction causes a layer of magnetic powder from a supply of the powder to creep up the outer surface of the tube in the opposite direction and across the ledge by somersaulting of the powder as the divergent flux system repeatedly scans the outer surface of the tube.
  • FIGS. la to Is are a time sequence of events which help to explain the principle on which the invention is based.
  • FIG. 2 illustrates a simple extension of the principle described with reference to FIGS. Ia to 1e;
  • FIG. 3 is a schematic representation of a magnetic printing and/or display device incorporating the invention.
  • FIG. 4 is a cross-sectional view of the device of FIG. 3.
  • a nonmagnetic support I has on its upper sur-. face '2 a small quantity of magnetic powder 3.
  • a bar magnet 4 disposed below the support I gives rise to a divergent system of magnet flux 5 above the surface 2.
  • the magnetic force on the powder can be resolved into two components; a horizontal component parallel to the surface 2 acting" towards the axis of the magnet, and a vertical component acting perpendicularly upwards relative to the surface 2. It isessential for carrying out the invention that the horizontal component is never sufficiently large to cause bulk movement of the powder along the surface 2 with the magnet; in other words it must be no greater than the friction, which is itself enhanced by the vertical component, between the powder and the surface. This condition can be satisfied by choosing a magnet of appropriate strength in relation to its distance belowthe surface 2, and the surface 2 can be artificially roughened to provide a better keying of the powder into the surface,
  • the magnet is sufficiently for from the powder 3 that the powder is not appreciably disturbed by the magnetic flux, but as the magnet is moved parallel to the underside of the support 1 in the direction A it eventually reaches the position shown in FIG. lb at which the magnetic powder forms into filaments which align themselves along the lines of flux, i.e., pointing away from the magnet.
  • FIG. 2 Asimple extension of this principle is shown in FIG. 2, in which the surface 2 is covered with a layer 6 of magnetic powder, and the magnet 4 is elongated to extend across the width of the support.
  • FIGS. 3 and 4 An embodiment of a magnetic printing and/or display device'incorporating the invention will now be described with reference to FIGS. 3 and 4.
  • the figures are not to scale and are only intended as a schematic illustration of the relevant parts of the device.
  • the device includes a drum 10 which is mounted in the opposite walls 16 of the device housing for rotation about an axis l I.
  • the cylindrical surface 12 of the drum is magnetizable and constitutes the surface on which matter to be printed and/or displayed is recorded as the drum rotates by a stationary set of recording heads (not shown).
  • Beneath the drum lies a trough 13 into which a supply of magnetic powder 14 can be introduced via the hopper 15, the endwalls of the trough being formed by the walls 16 of the device.
  • a nonmagnetic tube 17 is disposed horizontally along the trough.
  • the tube may be made of aluminum, and at each end meets the respective walls 16 so that magnetic powder in the trough cannot enter the inside of the tube.
  • a horizontal nonmagnetic ledge 18 extends tangentially from the top of the tube to below the drum 10, adjacent the cylindrical surface 12.
  • a magnetic rotor 19 is located inside the tube 17 for rotation about an axis 20 parallel with the tube.
  • the rotor comprises a plurality of mutually parallel bar magnets, such as 21, which are disposed side-by-side with their like poles adjacent, so effectively forming a flat rectangular magnet magnetized from edge to edge in a direction perpendicular to its axis.
  • Each edge of the rotor produces at the outer surface of the tube 17 a system of magnetic flux which is divergent in a plane perpendicular to the tube axis (FIG. 4).
  • FIGS. 3 and 4 The arrangement of the apparatus shown in FIGS. 3 and 4 is such that, according to the principle discussed with reference to FIGS. 1 and 2, rotation of the rotor in the direction of the arrow B (FIG. 4) causes a layer of powder 22 from the supply 14 to creep in the direction of the arrow C up the convex outer surface of the tube 17 and across the ledge 18, bysomersaulting of the powder as the flux system repeatedly scans the outer surface.
  • Each grain of powder is held in position on the tube by the attraction of its circumferential neighbors, but to assist somersaulting up the side of the tube it may be necessary to artificially roughen the outer surface.
  • the arrangement described also causes the layer to spread along the length of the tube, so that the trough need only be filled at one end. This is accomplished via the hopper as described previously.
  • the drum l0 rotates, in the direction of arrow D, in brushing contact with the layer of powder on the ledge.
  • the magnetized regions on its surface 12 become dusted to form a powder image of the matter for printing or display.
  • the purpose of the ledge 18 is to allow the drum to be offset from the tube I7 so that the magnetic rotor 19 does not affect the selective magnetization on the surface 12. Any powder which is not picked up by the magnetizable surface of the drum l0 falls over the edge of the ledge 18 and is thus returned to the supply in the trough 13.
  • apparatus for dusting the movable magnetizable surface of the device with magnetic powder comprising a convex nonmagnetic surface extending from a supply of the powder to a nonmagnetic ledge adjacent the magnetizable surface, and a magnetic rotor disposed behind the nonmagnetic surface and having its axis of rotation parallel thereto for producing at the nonmagnetic surface a system of magnetic flux which is divergent in a plane substantially perpendicular to the axis of rotation, the arrangement being such that rotation of the rotor in a given direction causes a layer of magnetic powder to creep in the opposite direction along the nonmagnetic surface and across the ledge by somersaulting of the powder as the flux field repeatedly scans the nonmagnetic surface.
  • apparatus for dusting the movable magnetizable surface of the device with magnetic powder comprising a substantially horizontal nonmagnetic tube, a magnetic rotor inside the tube whose axis of rotation is parallel with the tube, the rotor producing a system of magnetic flux at the outer surface of the tube which is divergent in a plane perpendicular to the tube axis, and a nonmagnetic ledge extending substantially tangentially from the outer surface of the tube to adjacent the magnetizable surface, the arrangement being such that rotation of the rotor in a given direction causes a layer of magnetic powder from a supply of the powder to creep up the outer surface of the tube in the opposite direction and across the ledge by somersaulting of the powder as the divergent flux system repeatedly scans the outer surface of the tube.
  • Apparatus according to claim 2 wherein the magnetic rotor is a flat rectangular magnet magnetized from edge to edge in a direction perpendicular to its axis of rotation.
  • the flat rectangular magnet comprises a plurality of mutually parallel bar magnets disposed side-hy-sidc with their like poles adjacent.
  • Apparatus according to claim 4 wherein the tube is disposed along a trough in which the supply of powder is contained.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
  • Printing Methods (AREA)
  • Non-Mechanical Conveyors (AREA)
US29330A 1969-05-29 1970-03-18 Magnetic powder applicator Expired - Lifetime US3640247A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB27166/69A GB1221268A (en) 1969-05-29 1969-05-29 Powder handling apparatus

Publications (1)

Publication Number Publication Date
US3640247A true US3640247A (en) 1972-02-08

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US29330A Expired - Lifetime US3640247A (en) 1969-05-29 1970-03-18 Magnetic powder applicator

Country Status (8)

Country Link
US (1) US3640247A (fr)
AU (1) AU1481870A (fr)
BE (1) BE759074A (fr)
CH (1) CH517638A (fr)
DE (1) DE2025514A1 (fr)
FR (1) FR2049697A5 (fr)
GB (1) GB1221268A (fr)
NL (1) NL7007866A (fr)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3882822A (en) * 1971-01-12 1975-05-13 Xerox Corp Apparatus for Developing Electrostatic Latent Images
US3900001A (en) * 1971-05-25 1975-08-19 Xerox Corp Developing apparatus
US3906121A (en) * 1971-05-25 1975-09-16 Xerox Corp Electrostatic development method using magnetic brush configuration transport
FR2325968A1 (fr) * 1975-09-26 1977-04-22 Xerox Corp Procede et dispositif de developpement d'images latentes magnetiques
US4108111A (en) * 1977-05-31 1978-08-22 Xerox Corporation Developer housing
DE2816426A1 (de) * 1977-04-18 1978-10-19 Du Pont Bepulverungsvorrichtung zum aufbringen von magnetisch anziehbaren tonerteilchen auf eine oberflaeche
DE2816501A1 (de) * 1977-04-18 1978-10-19 Du Pont Bepulverungsvorrichtung zum aufbringen von magnetisch anziehbaren tonerteilchen
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
US4550068A (en) * 1984-01-30 1985-10-29 Markem Corporation Vertical magnetic brush developing apparatus and method
US4613554A (en) * 1983-05-11 1986-09-23 Rhone-Poulenc Systemes Process for developing a latent image formed on a magnetic surface, device for carrying out the process and printing apparatus containing the said device

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3040704A (en) * 1957-04-16 1962-06-26 Rca Corp Apparatus for developing electrostatic printing
US3117891A (en) * 1960-09-26 1964-01-14 Xerox Corp Xerographic apparatus
US3392432A (en) * 1963-12-18 1968-07-16 Azoplate Corp Magnetic roller for electro-photographic development
US3438706A (en) * 1966-10-07 1969-04-15 Canon Kk Electrophotographic device
US3553464A (en) * 1967-03-27 1971-01-05 Ricoh Kk Device for detecting the density of developer in an electrostatographic duplicator
US3552355A (en) * 1968-04-22 1971-01-05 Xerox Corp Development apparatus

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3040704A (en) * 1957-04-16 1962-06-26 Rca Corp Apparatus for developing electrostatic printing
US3117891A (en) * 1960-09-26 1964-01-14 Xerox Corp Xerographic apparatus
US3392432A (en) * 1963-12-18 1968-07-16 Azoplate Corp Magnetic roller for electro-photographic development
US3438706A (en) * 1966-10-07 1969-04-15 Canon Kk Electrophotographic device
US3553464A (en) * 1967-03-27 1971-01-05 Ricoh Kk Device for detecting the density of developer in an electrostatographic duplicator
US3552355A (en) * 1968-04-22 1971-01-05 Xerox Corp Development apparatus

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3882822A (en) * 1971-01-12 1975-05-13 Xerox Corp Apparatus for Developing Electrostatic Latent Images
US3900001A (en) * 1971-05-25 1975-08-19 Xerox Corp Developing apparatus
US3906121A (en) * 1971-05-25 1975-09-16 Xerox Corp Electrostatic development method using magnetic brush configuration transport
FR2325968A1 (fr) * 1975-09-26 1977-04-22 Xerox Corp Procede et dispositif de developpement d'images latentes magnetiques
US4193376A (en) * 1976-11-29 1980-03-18 Sharp Kabushiki Kaisha Developer powder supply in magnet brush development
DE2816426A1 (de) * 1977-04-18 1978-10-19 Du Pont Bepulverungsvorrichtung zum aufbringen von magnetisch anziehbaren tonerteilchen auf eine oberflaeche
DE2816501A1 (de) * 1977-04-18 1978-10-19 Du Pont Bepulverungsvorrichtung zum aufbringen von magnetisch anziehbaren tonerteilchen
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
US4108111A (en) * 1977-05-31 1978-08-22 Xerox Corporation Developer housing
US4613554A (en) * 1983-05-11 1986-09-23 Rhone-Poulenc Systemes Process for developing a latent image formed on a magnetic surface, device for carrying out the process and printing apparatus containing the said device
US4550068A (en) * 1984-01-30 1985-10-29 Markem Corporation Vertical magnetic brush developing apparatus and method

Also Published As

Publication number Publication date
FR2049697A5 (fr) 1971-03-26
GB1221268A (en) 1971-02-03
NL7007866A (fr) 1970-12-01
AU1481870A (en) 1971-11-18
BE759074A (nl) 1971-05-18
DE2025514A1 (de) 1970-12-10
CH517638A (de) 1972-01-15

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