Magnetless speaker
US5487114A · kind A · utility
Inventor
Key dates
| Filing date | Feb 2, 1994 |
| Grant date | Jan 23, 1996 |
| Priority date | — |
| Expiry date | Feb 2, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04R9/00
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A lightweight speaker is constructed without permanent magnets by providing two coils, one of which is mounted on a movable membrane and the other of which is mounted on a fixed frame. The coils are mounted in close proximity to one another and excited by a common source signal from a common amplifier or the like in such a fashion that the electromagnetic fields created by the coils upon excitation interact to cause the coils to alternately attract and repel one another. One of the coils is fed with an excitation signal directly from the source. The other coil receives the source signal only indirectly, preferably via a bridge rectifier. The coils may take the form of conventional wound wires or, in a particularly sophisticated yet inexpensive embodiment, may be formed on a printed circuit board in the form of flat spirals. The resulting speaker is very lightweight and thus is well suited for use in automobiles, airplanes, and other applications in which weight minimization is important.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.