US3729596A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrodynamic sound pickup or sound-track cutting device
Assignee: Individual
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Filing: 1971-04-27
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Granted: 1973-04-24
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Expires: 1991-04-27
Abstract
Abstract An electrodynamic sound pickup which also functions as a soundtrack cutting device, two angularly disposed preferably stereophonic recordings of an engraved sound track are sensed by a phonograph needle mounted at the free end of a needle arm oscillating about its other end and carrying two transducer coils having their effective coil range disposed in a magnetic air gap formed by two spaced pole shoes opposing each other. The winding planes of the coils are arranged transversely with respect to the longitudinal direction of the needle arm, and one of the two pole shoes is split at its end adjacent the air gap accommodating both coils, so as to form a pair of pole-shoe fingers each extending through the free central space of each of the pair of coils wherein the effective coil portions disposed within the air gap extend along an arc with a center angle not exceeding 90*.
Inventors
- 👤 M Toth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 03:21
CPC Classifications
H; H04; H04R; H04R9/00; H04R9/12; H04R9/16
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
155 words
An electrodynamic transducer, comprising: a permanent-magnet yoke having a pair of spaced-apart poles defining an air gap between them, one of said poles being formed with a pair of codirectionally extending parallel but transversely spaced fingers of generally arc-segmental crosssection, the other pole being formed with a semicircular recess overhanging and spaced from said fingers; a stylus angularly oscillatable in said recess and generally extending along the axis thereof; an elongated spring anchored at one end to said one of said poles and extending generally axially and parallel to said fingers while carrying said stylus; and a pair of generally quadrant-shAped coplanar coils lying in a common plane transverse to said axis and secured, within a region overhung by said fingers to said stylus, said coils each surrounding a respective finger and having an arc-segmental effective winding portion extending through at most 90* of arc between the respective finger and the wall of said recess.
Claim 2
Dependent Claim
155 words
An electrodynamic transducer, comprising: a permanent-magnet yoke having a pair of spaced-apart poles defining an air gap between them, one of said poles being formed with a pair of codirectionally extending parallel but transversely spaced fingers of generally arc-segmental crosssection, the other pole being formed with a semicircular recess overhanging and spaced from said fingers; a stylus angularly oscillatable in said recess and generally extending along the axis thereof; an elongated spring anchored at one end to said one of said poles and extending generally axially and parallel to said fingers while carrying said stylus; and a pair of generally quadrant-shAped coplanar coils lying in a common plane transverse to said axis and secured, within a region overhung by said fingers to said stylus, said coils each surrounding a respective finger and having an arc-segmental effective winding portion extending through at most 90* of arc between the respective finger and the wall of said recess.
Claim 3
Dependent Claim
49 words
The electrodynamic transducer defined in claim 1 wherein said coils and said fingers are symmetrical with respect to an imaginary axial plane of said recess through said stylus, said coils having generally trapezoidal configuration with small bases proximal to said stylus and large bases forming said effective winding portions.
Claim 4
Dependent Claim
36 words
The electrodynamic transducer defined in claim 2, further comprising a mass of plastic material on said stylus, said small bases being embedded in said mass, said spring being a thin-metal member surrounded by an elastic cushion.
Claim 5
Dependent Claim
44 words
The electrodynamic transducer defined in claim 3 wherein said thin metal member is anchored to said mass and said transducer is provided with coil-retaining means confronting said cushion and provided with a stiff sheet surrounding the portion of said stylus proximal to said mass.
Claim 6
Dependent Claim
26 words
The electrodynamic transducer defined in claim 4 wherein said cushion is an elastic rubber body under pretension between said one of said poles and said sheet.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-23 | 1976-10-23 | 1977-04-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-23 | 1980-10-23 | 1981-04-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-23 | 1984-10-23 | 1985-04-24 | $7700.00 | Window Closed / Lapsed |