| US 7,492,918 B2 | ||
| Audio speaker with graduated voice coil windings | ||
| Enrique M. Stiles, Imperial Beach, Calif. (US); and Richard C. Calderwood, Portland, Oreg. (US) | ||
| Assigned to Step Technologies Inc., Minneapolis, Minn. (US) | ||
| Filed on Aug. 17, 2004, as Appl. No. 10/920,534. | ||
| Prior Publication US 2006/0039578 A1, Feb. 23, 2006 | ||
| Int. Cl. H04R 25/00 (2006.01) | ||
| U.S. Cl. 381—409 [381/408; 381/410] | 25 Claims |
| 1. An audio speaker driver comprising:
(A) a motor structure having a magnetic circuit including a magnetic air gap; and
(B) a voice coil assembly disposed within the magnetic air gap and including,
(1) a bobbin, and
(2) a voice coil coupled to the bobbin, wherein the voice coil includes,
(a) a center set of voice coil windings of wire wound about a center portion of the bobbin, and
(b) an outer set of voice coil windings of wire wound about outer portions of the bobbin above and below the center portion,
(c) wherein in at least one of,
(i) the center set of voice coil windings has a higher average electrical resistance per unit of voice coil height than the
outer set of voice coil windings, and
(ii) the center set of voice coil windings has a longer average length L per unit of voice coil height than the outer set
of voice coil windings.
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