CARTRIDGE FOR PICKUP
First Claim
1. An electromagnetic pickup cartridge comprising, in combination, a needle support mounted for vibration in accordance with sound tracks on a record engaged by a needle mounted in said support;
- a magnetized armature carried by and extending from said support;
two pairs of pole pieces arranged in spaced parallel relation, with each pair of pole pieces including a first pole piece and a second pole piece interconnected by a respective magnetic coil holder;
only each first pole piece having a pole face at one end in spaced magnetic relation with said armature, said pole faces extending in perpendicular facing relation to each other;
said armature being operatively associated with only said pole faces and terminating short of said second pole pieces; and
respective coils embracing each of said pole pieces, the coils on each second pole piece being wound reversely with respect to the coil on the associated first pole piece and connected in series therewith;
whereby external magnetic fLuxes are cancelled with respect to each channel including a first and second pole piece, so that high fidelity reproduction is provided in all channels of the record only by said first pole pieces and the coils thereon in accordance with vibrations of said support relative to said pole faces.
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Accused Products
Abstract
An electromagnetic pickup cartridge comprises a needle support mounted for vibration in accordance with sound tracks on a record engaged by a needle mounted on the support, and includes two pairs of pole pieces mounted in spaced parallel relation, with each pair including a first pole piece and a second pole piece interconnected by a respective magnetic coil holder. The two first pole pieces have pole faces at corresponding ends thereof in spaced relation with the support, and with the pole faces extending in perpendicular facing relation to each other. Respective coils embrace each pole piece, with the coil on each second pole piece being wound reversely relative to the coil on the associated first pole piece and connected in series therewith. Thereby, external magnetic fluxes are cancelled, with respect to each pair of pole pieces, so that high fidelity reproduction is provided in all channels of the record by the first pole pieces and the coils thereon in accordance with vibrations of the support relative to the pole faces. The support may comprise a paramagnetic metal tube in operative association with a fixedly position permanent magnet, or may comprise a tubular permanent magnet. Tension means are provided to preset the fulcrum of the support, and a mu-metal member is paced near the pole faces and the support to form a vertical compensation plate. From the physical standpoint, the pickup cartridge comprises a cartridge case mounting the pole pieces and a needle case mounting the needle support and readily assembled with the cartridge case.
8 Citations
8 Claims
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1. An electromagnetic pickup cartridge comprising, in combination, a needle support mounted for vibration in accordance with sound tracks on a record engaged by a needle mounted in said support;
- a magnetized armature carried by and extending from said support;
two pairs of pole pieces arranged in spaced parallel relation, with each pair of pole pieces including a first pole piece and a second pole piece interconnected by a respective magnetic coil holder;
only each first pole piece having a pole face at one end in spaced magnetic relation with said armature, said pole faces extending in perpendicular facing relation to each other;
said armature being operatively associated with only said pole faces and terminating short of said second pole pieces; and
respective coils embracing each of said pole pieces, the coils on each second pole piece being wound reversely with respect to the coil on the associated first pole piece and connected in series therewith;
whereby external magnetic fLuxes are cancelled with respect to each channel including a first and second pole piece, so that high fidelity reproduction is provided in all channels of the record only by said first pole pieces and the coils thereon in accordance with vibrations of said support relative to said pole faces.
- a magnetized armature carried by and extending from said support;
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2. An electromagnetic pickup cartridge, as claimed in claim 1, including a vertical compensation plate of mu-metal positioned adjacent said pole faces and said armature.
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3. An electromagnetic pickup cartridge, as claimed in claim 1, in which said pole pieces comprise relatively elongated substantially flat bars;
- each magnetic coil holder comprising a substantially rectangular base and a pair of arms extending upwardly from an outer edge of said base and each juxtaposed with a respective first and second pole piece, said bases being substantially coplanar with their inner edges in adjacent spaced relation;
said pole faces comprising bent ends of said first pole pieces bent inwardly toward each other to define an opened vee having an included angle of 90* and said armature intersecting perpendicularly the triangle defined by said pole faces.
- each magnetic coil holder comprising a substantially rectangular base and a pair of arms extending upwardly from an outer edge of said base and each juxtaposed with a respective first and second pole piece, said bases being substantially coplanar with their inner edges in adjacent spaced relation;
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4. An electromagnetic pickup cartridge, as claimed in claim 1, in which said support comprises a first lightweight tubular member of non-ferrous metal supporting the needle, and a second tubular armature of ferrous metal supporting said first member and positioned adjacent said pole faces.
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5. An electromagnetic pickup cartridge, as claimed in claim 4, including a permanent magnet in operative relation with said armature to magnetize the latter.
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6. An electromagnetic pickup cartridge, as claimed in claim 4, including tension means connected to the inner end of said armature and controlling the fulcrum point thereof.
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7. An electromagnetic pickup cartridge, as claimed in claim 4, in which said armature is a permanent magnet.
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8. An electromagnetic pickup cartridge, as claimed in claim 1, including a cartridge case mounting said pole pieces and said magnetic coil holders;
- and a needle case mounting said support;
said cartridge case and said needle case being formed with interfitting configurations whereby the two cases may be readily engaged with each other and disengaged from each other.
- and a needle case mounting said support;
Specification