Inductive braking in a dual coil speaker driver unit
US5828767A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 22, 1997 |
| Grant date | Oct 27, 1998 |
| Priority date | — |
| Expiry date | Sep 22, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04R2209/043
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An electro-magnetic loudspeaker, with dual voice coils operating in corresponding magnetic fields in annular gaps between permanent magnet pole pieces, is provided with a single short-circuited braking coil of one or more turns mounted on the voice coil form midway between the two voice coils. The braking coil has minimal effect on normal operation of the loudspeaker, but introduces an inductive braking effect from counter-EMF whenever the voice coil assembly displacement approaches a working limit in either direction, as the braking coil enters a corresponding one of the two magnetized gaps. Thus bidirectional braking/damping is accomplished in a dual coil speaker by the addition of a single braking coil, which could be simply a one turn ring; whereas bidirectional inductive braking in a speaker with a single voice coil requires two such braking coils flanking the voice coil. The single braking/damping coil can be brought out to terminals for connecting it in a loop circuit with an active feedback driver and/or a network of one or more reactive components, for modifying and enhancing the braking/damping action.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.