Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F7/00—Magnets
  • H01F7/02—Permanent magnets [PM]
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/0013—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor using fillers dispersed in the moulding material, e.g. metal particles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/14—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles
  • B29C45/14336—Coating a portion of the article, e.g. the edge of the article
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F7/00—Magnets
  • H01F7/02—Permanent magnets [PM]
  • H01F7/0231—Magnetic circuits with PM for power or force generation
  • H01F7/0252—PM holding devices
  • H01F7/0268—Magnetic cylinders
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
  • B29K2995/0003—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds having particular electrical or magnetic properties, e.g. piezoelectric
  • B29K2995/0008—Magnetic or paramagnetic
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
  • B29L2031/00—Other particular articles
  • B29L2031/32—Wheels, pinions, pulleys, castors or rollers, Rims
  • B29L2031/324—Rollers or cylinders having an axial length of several times the diameter, e.g. embossing, pressing or printing

Definitions

• the invention relates to electrophotography and more particularly to developer magnet rolls for electrophotography.
• Developer magnet rolls are typically made of strontium ferrite in a nylon binder and are formed into cylindrical shapes that function within a surrounding cylindrical developing sleeve.
• the magnetic pole pattern which is contained within the core of the magnet is typically comprised of four or more alternating North-South poles formed longitudinally along the cylinder, resembling a "four leaf clover pattern" when viewed from the end.
• the core is supported within the developing sleeve framework via end shafts that are integral to the developer magnet roll.
• the developer magnet roll which is usually composed of a ferrite and a binder, is formed by the following methods.
• the magnets are typically assembled onto a cold rolled steel shaft for strength and magnetized longitudinally during the extrusion process and formed into a hollow cylinder, then demagnetized and finally, remagnetized into a final pole configuration using electromagnets after assembly.
• This method is inherently expensive due to the multi-step process of extruding the magnetic compound, gluing the soft, flexible magnet onto a shaft and magnetizing the developer magnet into a final desired pattern.
• a strong metallic shaft is insert molded within a ferrite and soft, flexible thermoplastic such as ethylene vinyl acetate (EVA) binder to form the developer magnet roll with magnetization accomplished with permanent magnets within the mold or with electromagnets.
• EVA ethylene vinyl acetate
• the magnets are typically 100% molded to include the small diameter end mounting means.
• the roll magnets using a nylon binder are either magnetized during molding with the use of permanent l magnets or by using electromagnetic coils within the mold to partially magnetize the roll with final magnetization occurring after molding.
• the nylon binder magnets have acceptable performance and are inexpensive, but if the ratio of weight to length and/or magnet diameter to mounting diameter is large, the end shafts are fragile and can break easily. If the end shaft diameters are increased for added strength, then acceptable strength is obtained.
• the mounting diameter size is limited in many applications, due to the surrounding geometry and the necessity for adequate clearance by adjoining elements, such as the inside diameter of the developer sleeve end plugs, through which the end shafts protrude.
• Completed magnet rolls must be straight with a minimum circular run out to have acceptable magnetic performance.
• U.S. Patent 4,557,582 describes the planar attachment of magnetic strips to a non-circular cross sectioned, asymmetrical polygon shaped supporting shaft which has at least the end portions shaped this way to attach it to a cartridge.
• the magnetic strips when made separately are difficult to assemble together in a long cylindrical shaped envelope and the shaft provides the mechanical mounting method.
• U.S. Patent 4,580,121 describes ferrite magnets with a rubber binder held on an aluminum extruded shaft that has a plurality of ribs and is bound together using heat shrink tubing.
• the nonmagnetic aluminum extruded shaft provides the vehicle to mount the strip magnets.
• U.S. Patent 4,604,042 describes an insert-molding method that places a central shaft within a bonded (nylon) ferrite magnet to compensate for large length to diameter: ratios greater than 5 where rare earth permanent magnets within the mold magnetize the final cylindrical magnet roll.
• U.S. Patent 4,872,4108 describes a ferrite magnet with nylon binder that includes a cross sectioned flat drive or longitudinal end polygon protrusion at each end.
• U.S. Patent 4,954,800 describes the use of electromagnetic magnetization of roll magnets during molding to establish longitudinal poles.
• Patent 5,682,587 describes a universal hollow magnet with metal filled resin bearings of different configurations which have unique end shaft shapes like D's or squares. These support bearings are described as conical end support members that can also perform the electrical contact with the bias voltage of the cartridge. The end shafts perform multiple purposes including support, an accurate bearing surface and an electrical contact point.
• U.S. Patent 3,149,403 pertains to stub shafts inserted or insert-molded into a non-magnetic core or body, to which magnetic modules are subsequently attached.
• the magnet body is a composite structure of magnetic and nonmagnetic elements.
• U.S. Patent 4,142,218, relates to a magnetic roll created as a composite structure consisting of a non-magnetic body and/with end hubs to which longitudinal magnet inserts are added, and to which end shafts are inserted post molding of the body/hubs.
• U.S. Patent 5,583,473 discloses one shaft end integrally molded as a part of the magnet roll body, and the second end shaft being press-fit past the molding of the body/first-end.
• an improved developer magnet roll for use in a developer sleeve for electrophotography is provided.
• Figure 1 is a longitudinal cross-sectional view showing a magnet roll according to the invention.
• a magnet body roll 1 comprised of a particulate ferrite material, such as strontium ferrite and a binder, and end pin shafts 2, attached thereto.
• the end pin shafts are made of a material such as metal, ceramic or plastic.
• the end pin shafts 2, 30 are inserted into a mold and the magnet body roll 2 is formed during a standard injection molding process (i.e., by injecting melted binder with the ferrite particles
• a typical binder for the ferrite is a rigid thermoplastic such as nylon 6 or nylon 12.
• the injection molded developer magnet roll exhibits improved strength, improved straightness, improved processing and cost savings through the incorporation of the insert molded end shafts, especially in situations with a large ratio of overall magnet diameter to support shaft diameter.
• a preferred embodiment of this invention utilizes a non-magnetic material for the end shafts, such as non-magnetic grades of stainless steel. This embodiment is preferable when used with injection molding equipment containing permanent magnets to produce said magnetic rollers.

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Manufacturing & Machinery (AREA)
• Power Engineering (AREA)
• Electromagnetism (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Dispersion Chemistry (AREA)
• General Physics & Mathematics (AREA)
• Magnetic Brush Developing In Electrophotography (AREA)
• Injection Moulding Of Plastics Or The Like (AREA)
• Rolls And Other Rotary Bodies (AREA)
• Moulds For Moulding Plastics Or The Like (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=22105921

Family Applications (1)

Country Status (6)

Families Citing this family (2)

Citations (5)

Family Cites Families (1)

• 1999
  • 1999-05-04 AU AU41826/99A patent/AU4182699A/en not_active Abandoned
  • 1999-05-04 WO PCT/US1999/009802 patent/WO1999056933A1/en not_active Ceased
  • 1999-05-04 CN CN99805802A patent/CN1299312A/zh active Pending
  • 1999-05-04 EP EP99925571A patent/EP1100668A4/de not_active Withdrawn
  • 1999-05-04 JP JP2000546931A patent/JP2002514002A/ja active Pending
  • 1999-05-04 KR KR1020007012147A patent/KR20010043214A/ko not_active Withdrawn

Patent Citations (5)

Non-Patent Citations (3)

Also Published As

Similar Documents

Legal Events