US3205414A - Correction magnets for cathode-ray tubes and methods for magnetizing same - Google Patents

Correction magnets for cathode-ray tubes and methods for magnetizing same Download PDF

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US3205414A
US3205414A US121444A US12144461A US3205414A US 3205414 A US3205414 A US 3205414A US 121444 A US121444 A US 121444A US 12144461 A US12144461 A US 12144461A US 3205414 A US3205414 A US 3205414A
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magnetic
rings
magnetizing
correction
annular portion
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Expired - Lifetime
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US121444A
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Erich A Steingroever
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Magnetfabrik Bonn GmbH
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Magnetfabrik Bonn GmbH
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Priority claimed from GB958062A external-priority patent/GB983257A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/06—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder
    • H01F1/08—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together
    • H01F1/083—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together in a bonding agent
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/10—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials non-metallic substances, e.g. ferrites, e.g. [(Ba,Sr)O(Fe2O3)6] ferrites with hexagonal structure
    • H01F1/11—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials non-metallic substances, e.g. ferrites, e.g. [(Ba,Sr)O(Fe2O3)6] ferrites with hexagonal structure in the form of particles
    • H01F1/113—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials non-metallic substances, e.g. ferrites, e.g. [(Ba,Sr)O(Fe2O3)6] ferrites with hexagonal structure in the form of particles in a bonding agent
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/54—Arrangements for centring ray or beam
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/4902—Electromagnet, transformer or inductor
    • Y10T29/49075—Electromagnet, transformer or inductor including permanent magnet or core
    • Y10T29/49076—From comminuted material

Definitions

  • the invention relates to a magnetic focussing device for the electron beam of a cathode ray tube and is particularly suitable for such tubes in television receivers.
  • the known correction rings may consist of a plastic base in which an annular wire of permanent magnetic material is embedded.
  • the invention eliminates said drawback and makes it possible to manufacture correction rings of the type described by an injection or compression molding process as single integral units.
  • only the annular part of the correction rings is magnetized while the manipulating handles are not magnetized or only so little as not to interfere with the correcting field.
  • the operating handles are arranged in the neutralzone of the correction rings.
  • Such arrangement makes the magnetic stray field, with respect to the center of the ring, very small; in addition, it may eliminate the need of a specific shield during magnetization, or a demagnetization of the handles.
  • FIG. 1 shows, diagrammatically, an axial sectional view of magnetic correction rings around the neck of a cathode ray tube
  • FIG. 2 shows a view of a magnetic correction ring according to the invention
  • FIG. 3 shows the arrangement for magnetizing the rings
  • FIG. 4 is a view of a modification of the ring shown in FIG. 2.
  • two coaxial spaced correction rings are used which can be rotatably displaced with respect to each other to adjust the strength and direction of the correction field.
  • Each correction ring 1 is prepared from a mixture of a magnetic powder and a thermoplastic binder, for instance in a die casting procedure.
  • the ring is magnetized by means of a magnetizing coil 2 from the inside so as to form a magnetic field in direction of the arrow N-S, which field runs in the ring approximately along the broken lines.
  • the two manipulating handles 3 and 4 are surrounded by the sheet iron sleeves 5 and 6, so that they remain substantially un- 3,205,414 Patented Sept. 7, 1965 Said sleeves are removed after magnetization.
  • the manipulating handles or other projections extending beyond the circular periphery of the ring may be protected, during magnetization, by means of sleeves made of a good electrically conducting material, for instance of copper or aluminum. It is also possible to prevent magnetizing of said projections during the magnetizing operations by means of additional coils; preferably, such additional coils are arranged in series with the main magnetizing coil and compensate the magnetizing field at the projections.
  • the interfering projections or manipulating handles may be subsequently demagnetized.
  • interference of the manipulating handles with the correction field is minimized by arranging said handles (7, 8 in FIG. 4) in the neutral zone of the correction rings.
  • said handles (7, 8 in FIG. 4) in the neutral zone of the correction rings.
  • the magnetic stray field of the projections with relation to the center of the ring becomes so weak that a special shielding during magnetizing, or demagnetization, can be omitted.
  • any magnetic material may be employed for the correction rings.
  • Said pennanent magnetic materials are mixtures of a non-magnetic thermoplastic binder with particles of the type and alloys known under the names Alni and Alnico, which have the following composition:
  • PbO-6Fe O may be used.
  • thermoplastic resin such as homopolymers .or copolymers of vinyl chloride, polyarnides, cellulose acetate, also natural or synthetic rubbers, may be used. I prefer to employ a polyalkylene like polyethylene.
  • a permanent magnetic device for a cathode-ray tube neck comprising a correction ring having a magnetized annular portion adapted to surround said neck and a manipulating handle projecting from the outer periphery of said annular portion, said annular portion and handle forming a unitary structure made of the same magnetic composition, said manipulating handle having a magnetic characteristic causing substantially no interference with the magnetic field of said annular portion.
  • annular portion and handle consist essentially of a mixture of a non-magnetic thermoplastic resin binder with a member of the group consisting of nickel-aluminum-iron alloys and ferrites MO-6Fe O wherein M is a member of the group consisting of Ba, Sr, and Pb.
  • a magnetic correction device for a cathode ray tube comprising a pair of coaXially spaced magnetized correction rings to surround the neck of said tube and supported for rotatable displacement of one ring to the other, each of said rings having a manipulating handle projecting from the outer periphery thereof, the annular portions of said rings and said handles forming a unitary structure made of the same magnetic composition, and said manipulating handles each having a magnetic characteristic causing substantially no interference with the magnetic field ,of said annular portions.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Video Image Reproduction Devices For Color Tv Systems (AREA)

Description

Sept. 7, 1965 E. A. STEINGRQEVER CORRECTION MAGNETS FOR GATHODE-RAY TUBES AND METHODS FOR MAGNETIZING SAME Filed July 5, 1961 aqfi/apfFm iz'iaf 129250270 3x175 CZ/e/ur/m/v ran gas United States Patent 3,205,414 CORRECTION MAGNETS FOR CATHODE RAY gUBES AND METHODS FOR MAGNETIZING Erich A. Steingroever, Bonn (Rhine), Germany, assignor to Magnetfabrik Bonn Gewerkschaft Windhorst, Bonn, Germany Filed July 3, 1961, Ser. No. 121,444 Claims priority, application Germany, July 6, 1960, M 45,842 8 Claims. (Cl. 317-200) The invention relates to a magnetic focussing device for the electron beam of a cathode ray tube and is particularly suitable for such tubes in television receivers.
It is known to use permanent ring magnets which are positioned around the cathode ray tube neck and produce a magnetic field of several oersted transversely of the direction of the electron beam. By turning such socalled correctionrings, the influence of external fields and of the magnetic earth field on the position of the image can be corrected. For manipulation, the rings are provided with handles projecting into the plane of the structure.
The known correction rings may consist of a plastic base in which an annular wire of permanent magnetic material is embedded.
Heretofore, it has not been possible to produce such correction rings in a simple procedure only from a magnetic powder and binder as integral structures where also the handles consist of magnetic material. The reason was that, on magnetizing, also said handles became magnetic and produced a distortion of the magnetic field in the center of the ring.
The invention eliminates said drawback and makes it possible to manufacture correction rings of the type described by an injection or compression molding process as single integral units. In accordance with the invention, only the annular part of the correction rings is magnetized while the manipulating handles are not magnetized or only so little as not to interfere with the correcting field.
In a preferred embodiment of the invention, the operating handles are arranged in the neutralzone of the correction rings. Such arrangement makes the magnetic stray field, with respect to the center of the ring, very small; in addition, it may eliminate the need of a specific shield during magnetization, or a demagnetization of the handles.
The invention will be described with reference to the accompanying drawings, in which FIG. 1 shows, diagrammatically, an axial sectional view of magnetic correction rings around the neck of a cathode ray tube;
FIG. 2 shows a view of a magnetic correction ring according to the invention;
FIG. 3 shows the arrangement for magnetizing the rings, and
FIG. 4 is a view of a modification of the ring shown in FIG. 2. a
As it will be seen from FIG. 1 preferably two coaxial spaced correction rings are used which can be rotatably displaced with respect to each other to adjust the strength and direction of the correction field.
Each correction ring 1 is prepared from a mixture of a magnetic powder and a thermoplastic binder, for instance in a die casting procedure. The ring is magnetized by means of a magnetizing coil 2 from the inside so as to form a magnetic field in direction of the arrow N-S, which field runs in the ring approximately along the broken lines. During magnetization, the two manipulating handles 3 and 4 are surrounded by the sheet iron sleeves 5 and 6, so that they remain substantially un- 3,205,414 Patented Sept. 7, 1965 Said sleeves are removed after magnetization.
Instead of using sheet iron sleeves 5 and 6, the manipulating handles or other projections extending beyond the circular periphery of the ring may be protected, during magnetization, by means of sleeves made of a good electrically conducting material, for instance of copper or aluminum. It is also possible to prevent magnetizing of said projections during the magnetizing operations by means of additional coils; preferably, such additional coils are arranged in series with the main magnetizing coil and compensate the magnetizing field at the projections.
It is also possible to magnetize the correction rings without special precautions. In such a case, the interfering projections or manipulating handles may be subsequently demagnetized.
In another embodiment of the invention, interference of the manipulating handles with the correction field is minimized by arranging said handles (7, 8 in FIG. 4) in the neutral zone of the correction rings. In this arrangement, the magnetic stray field of the projections with relation to the center of the ring becomes so weak that a special shielding during magnetizing, or demagnetization, can be omitted.
I prefer to make the manipulating handles of the two rings of different size ,or form to facilitate distinguishing the one ring from the other.
Any magnetic material may be employed for the correction rings. I prefer to make the rings by injection molding of a permanent magnetic powder as disclosed in my copending application Ser. No. 92,912, filed March 2, 1961, for a Magnetic Composition. Said pennanent magnetic materials are mixtures of a non-magnetic thermoplastic binder with particles of the type and alloys known under the names Alni and Alnico, which have the following composition:
or PbO-6Fe O may be used.
As non-magnetic binders, any thermoplastic resin such as homopolymers .or copolymers of vinyl chloride, polyarnides, cellulose acetate, also natural or synthetic rubbers, may be used. I prefer to employ a polyalkylene like polyethylene.
Iclaim:
1. A permanent magnetic device for a cathode-ray tube neck comprising a correction ring having a magnetized annular portion adapted to surround said neck and a manipulating handle projecting from the outer periphery of said annular portion, said annular portion and handle forming a unitary structure made of the same magnetic composition, said manipulating handle having a magnetic characteristic causing substantially no interference with the magnetic field of said annular portion.
2. A magnetic device as claimed in claim 1 wherein said handle is arranged in the magnetically neutral zone of the ring.
3. A magnetic device as claimed in claim 1 wherein said annular portion and handle consist essentially of a mixture of a non-magnetic thermoplastic resin binder with a member of the group consisting of nickel-aluminum-iron alloys and ferrites MO-6Fe O wherein M is a member of the group consisting of Ba, Sr, and Pb.
4. A magnetic correction device for a cathode ray tube comprising a pair of coaXially spaced magnetized correction rings to surround the neck of said tube and supported for rotatable displacement of one ring to the other, each of said rings having a manipulating handle projecting from the outer periphery thereof, the annular portions of said rings and said handles forming a unitary structure made of the same magnetic composition, and said manipulating handles each having a magnetic characteristic causing substantially no interference with the magnetic field ,of said annular portions.
5. A device as claimed in claim 4 wherein the handles of said rings have dilferent size.
6. A device as claimed in claim 4 wherein the handles of said rings have diiferent form.
7. The method of magnetizing magnetic correction rings for cathode ray tubes, which rings are provided with'integral projecting handles of the same material as said rings, comprising the steps of shielding said handles References Cited by the Examiner UNITED STATES PATENTS 2,542,924: 2/51 Heppner 317200 2,817,034 12/57 Covill 317200 2,922,908 1/ Heller 317-200 2,950,407 8/60 Barkow et al. 31384 FOREIGN PATENTS 489,657 1/z53 Canada. 85 8,627 1/ 61 Great Britain.
LARAMIE E. ASKIN, Acting Primary Examiner.
SAMUEL BERNSTEIN, JOHN F. BURNS, Examiners.

Claims (2)

1. A PERMANENT MAGNETIC DEVICE FOR A CATHODE-RAY TUBE NECK COMPRISING A CORRECTION RING HAVING A MAGNETIZED ANNULAR PORTION ADAPTED TO SURROUND SAID NECK AND A MANIPULATING HANDLE PROJECTING FROM THE OUTER PERIPHERY OF SAID ANNULAR PORTION, SAID ANNULAR PORTION AND HANDLE FORMING A UNITARY STRUCTURE MADE OF THE SAME MAGNETIC COMPOSITION, SAID MANIPULATING HANDLE HAVING A MAGNETIC CHARACTERISTIC CAUSING SUBSTANTIALLY NO INTERFERENCE WITH THE MAGNETIC FIELD OF SAID ANNULAR PORTION.
7. THE METHOD OF MAGNETIZING MAGNETIC CORRECTION RINGS FOR CATHODE RAY TUBES, WHICH RINGS ARE PROVIDED WITH INTEGRAL PROJECTING HANDLES OF THE SAME MATERIAL AS SAID RINGS, COMPRISING THE STEPS OF SHIELDING SAID HANDLES FROM MAGNETIC EFFECTS AND MAGNETIZING THE ANNULAR PORTION OF SAID RING WHILE SAID HANDLE IS SHIELDED.
US121444A 1960-07-06 1961-07-03 Correction magnets for cathode-ray tubes and methods for magnetizing same Expired - Lifetime US3205414A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DEM45842A DE1186561B (en) 1960-07-06 1960-07-06 Ring-shaped correction magnet for cathode ray tubes and method for manufacturing the correction magnet
GB958062A GB983257A (en) 1962-03-13 1962-03-13 Improvements in or relating to corrector magnets

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3303443A (en) * 1964-08-31 1967-02-07 Rca Corp Magnetic device having elliptically shaped opening

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2542924A (en) * 1950-06-21 1951-02-20 Myron R Heppner Ion trap
CA489657A (en) * 1953-01-13 Richard James Court Patrick Beam centering devices for cathode ray tubes
US2817034A (en) * 1952-10-23 1957-12-17 Cossor Ltd A C Magnetic focussing field arrangements for cathode ray tubes
US2922908A (en) * 1955-08-31 1960-01-26 Westinghouse Electric Corp Retaining device
US2950407A (en) * 1956-12-21 1960-08-23 Rca Corp Electric beam controlling apparatus
GB858627A (en) * 1959-10-26 1961-01-11 Mullard Ltd Cathode-ray tube deflector magnets

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB670021A (en) * 1949-02-18 1952-04-09 Patrick Richard James Court Improvements in beam centering devices for cathode ray tubes
DE1782320U (en) * 1958-05-20 1959-02-05 Telefunken Gmbh ARRANGEMENT FOR THE CENTERING OF THE ELECTRON BEAM OF A CATHODE BEAM TUBE, IN PARTICULAR FOR TELEVISION RECEIVERS.
DE1779082A1 (en) * 1968-07-05 1971-12-02 Naue Kg E A H Molded ready-made cushions made of foam

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA489657A (en) * 1953-01-13 Richard James Court Patrick Beam centering devices for cathode ray tubes
US2542924A (en) * 1950-06-21 1951-02-20 Myron R Heppner Ion trap
US2817034A (en) * 1952-10-23 1957-12-17 Cossor Ltd A C Magnetic focussing field arrangements for cathode ray tubes
US2922908A (en) * 1955-08-31 1960-01-26 Westinghouse Electric Corp Retaining device
US2950407A (en) * 1956-12-21 1960-08-23 Rca Corp Electric beam controlling apparatus
GB858627A (en) * 1959-10-26 1961-01-11 Mullard Ltd Cathode-ray tube deflector magnets

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3303443A (en) * 1964-08-31 1967-02-07 Rca Corp Magnetic device having elliptically shaped opening

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