Full range planar magnetic transducers and arrays thereof
Contemplated planar magnetic transducers include a magnet and diaphragm arrangement such that substantially homogenous vertical and high horizontal magnetic flux density is realized in the inter-magnet space. Most preferably, the diaphragm is a tensioned polymer membrane in which the voice coil covers a significant portion of the active portion of the membrane, and the magnets are rare-earth metal-type magnets of ultra-high strength. Particularly preferred planar magnetic transducers allow for exceptionally large excursion of the diaphragm in a substantially homogenous magnetic field at virtually no distortion, thereby providing heretofore unachieved sound pressure levels. Arrays of such and other transducers are disclosed that provide a full-range speaker with acoustic plane source characteristics.
1. A full-range transducer comprising:
a frame to which are coupled a plurality of magnets and a diaphragm under tension wherein the tensioned diaphragm is disposed between at least two of the magnets, wherein at least 85% of an active area of the diaphragm has substantially the same tension, and wherein the magnets are arranged relative to each other such that:
(a) an intermagnet gap between the at least two of the magnets is selected such as to allow diaphragm excursions of the tensioned diaphragm for production of sound pressure levels of at least 120 db at 1 m distance;
(b) average magnetic flux density between the at least two magnets in a plane perpendicular to the diaphragm is at least 0.35 T and is substantially homogenous across at least 70% of a distance between the at least two magnets;
(c) average magnetic flux density between a third magnet and one of the at least two magnets in a plane of the diaphragm is at least 0.3 T;
(d) wherein at least 60% of an active area of the diaphragm are covered by a voice coil; and
wherein the magnets and the voice coil are arranged relative to each other and wherein the tensioned diaphragm is under a tension such as to allow pistonic movement of the active area of the diaphragm to thereby reduce dispersion of sound.
2. The full-range transducer of claim 1 wherein the distance between the at least two of the magnets is at least 5 mm.
3. The full-range transducer of claim 1 wherein the average magnetic flux density between the at least two magnets in a plane perpendicular to the diaphragm is at least 0.45 T.
4. The full-range transducer of claim 1 wherein the average magnetic flux density between the at least two magnets in a plane perpendicular to the diaphragm is at least 0.55 T.
5. The full-range transducer of claim 1 wherein the average magnetic flux density between the third magnet and one of the at least two magnets in a plane of the diaphragm is at least 0.35 T.
6. The full-range transducer of claim 1 wherein the average magnetic flux density between the third magnet and one of the at least two magnets in a plane of the diaphragm is at least 0.4 T.
7. The full-range transducer of claim 1 wherein at least 70% of the active area of the diaphragm are covered by the voice coil.
8. The full-range transducer of claim 1 wherein the diaphragm comprises a tensioned polyamide membrane.
9. The full-range transducer of claim 1 wherein the diaphragm comprises a tensioned polyester membrane.
10. The full-range transducer of claim 1 wherein at least 95% of the active area of the diaphragm has substantially the same tension.
11. The full-range transducer of claim 1 wherein the distance between the at least two of the magnets is at least 5 mm, wherein the average magnetic flux density between the at least two magnets in a plane perpendicular to the diaphragm is at least 0.55 T, and wherein the average magnetic flux density between the third magnet and one of the at least two magnets in a plane of the diaphragm is at least 0.4 T.
12. The full-range transducer of claim 1 wherein the plurality of magnets are on each side of the diaphragm arranged in parallel with alternating polarity in neighboring magnets and in same polarity in opposing magnets.
13. The full-range transducer of claim 1 wherein the at least two magnets are coupled to each other by a spacer element.
14. The full-range transducer of claim 1 wherein the at least two magnets comprise a rare earth metal.
15. An array of speakers comprising a full-range transducer according to claim 1 .