Planar voice coil loudspeaker

Claim 2

An audio transducer comprising: a first diaphragm, an electrical conductor on at least one face of said first diaphragm, said electrical conductor including spaced parallel conductor portions, a fixed magnet arrangement disposed substantially parallel to said diaphragm spaced from said at least one face thereof, the magnet arrangement comprising a plurality of substantially parallel permanent magnets so disposed with respect to said diaphragm that a part of the magnetic field created thereby lies in the plane of said diaphragm and orthogonal to said parallel portions of said conductor, a second diaphragm of smaller area than said first diaphragm located between said first diaphragm and said fixed magnet arrangement, and an electrical conductor on said second diaphragm, said electrical conductor having at least one conductor portion substantially parallel to said parallel portions of said first conductor.

Claim 3

The audio transducer of claim 1 further comprising means holding said second diaphragm under a tension greater than the tension in said first diaphragm, and means feeding the same electrical signals to both diaphragms, whereby said second diaphragm acts as a treble diaphragm by virtue of the tension applied thereto.

Claim 4

The audio transducer of claim 2 wherein said tension is applied to said second diaphragm in a direction substantially parallel to said parallel conductor portions of said first diaphragm.

Claim 5

The audio transducer of claim 1 wherein there is a further fixed magnet arrangement disposed in spaced parallel relationship with said first diaphragm on the side thereof remote from said second diaphragm.

Claim 6

The audio transducer of claim 4 wherein there is further provided a second conductor on the face of said fiRst diaphragm opposite said at least one face thereof, said second conductor also including a plurality of spaced parallel conductor portions extending substantially parallel to said parallel conductor portions of said conductor on said at least one face of said diaphragm.

Claim 7

The audio transducer of claim 1 wherein said magnets are made of a material comprising magnetised particles embedded in a matrix of non-magnetic material.

Claim 8

An audio transducer comprising: a diaphragm corrugated along a first direction, means supporting said diaphragm along the edges thereof parallel to said corrugations, an electrical conductor on at least one face of said diaphragm, said electrical conductor having parallel conductor portions extending orthogonally of said corrugations, a fixed magnet arrangement disposed in spaced relationship substantially parallel to the general plane of said diaphragm on at least one side thereof, said magnet arrangement comprising a plurality of substantially parallel permanent magnets so disposed with respect to said diaphragm that a part of the magnetic field created thereby lies in the plane of said diaphragm and orthogonal to said parallel portions of said conductor, said magnets being formed of a material comprising magnetised particles embedded in a matrix of non-magnetic material, and, a second diaphragm located in a position between but spaced from said corrugated diaphragm and said fixed permanent magnet arrangement.

Claim 9

An audio transducer comprising: a diaphragm corrugated along a first direction, means supporting said diaphragm along the edges thereof parallel to said corrugations, an electrical conductor on at least one face of said diaphragm, said electrical conductor having parallel conductor portions extending orthogonally of said corrugations, a fixed magnet arrangement disposed in spaced relationship substantially parallel to the general plane of said diaphragm on at least one side thereof, said magnet arrangement comprising a plurality of substantially parallel permanent magnets so disposed with respect to said diaphragm that a part of the magnetic field created thereby lies in the plane of said diaphragm and orthogonal to said parallel portions of said conductor, said magnets being formed of a material comprising magnetised particles embedded in a matrix of non-magnetic material, and, a second diaphragm located in a position between but spaced from said corrugated diaphragm and said fixed permanent magnet arrangement.

Claim 10

The audio transducer of claim 7 wherein there is provided a further conductor having parallel conductor portions on the face of said corrugated diaphragm opposite said at least one face thereof, and a second fixed permanent magnet arrangement in spaced relation substantially parallel to the general plane of said diaphragm and on the side thereof remote from said at least one face.

Claim 11

The audio transducer of claim 8 wherein said parallel conductor portions of said further conductor are substantially parallel to said parallel conductor portions of said conductor on said at least one face of said diaphragm.

Claim 12

An audio transducer comprising: a corrugated diaphragm, a conductor on at least one face of said corrugated diaphragm, said conductor having a plurality of spaced parallel series-connected conductor strips, a fixed permanent magnet structure spaced from said at least one face of said corrugated diaphragm, the magnetic field from said permanent magnet structure having a part extending orthogonally of said parallel conductor strips and lying substantially in the general plane of said corrugated diaphragm, a backing plate supporting said fixed permanent magnet structure, said backing plate being perforated at least in the region between adjacent magnets of said structure, a second diaphragm between said fixed magnet structure and said corrugated diaphragm, and spaced therefrom, means holding said second diaphragm in tension applied perpendicularly with respect to said corrugations of said corrugated diaphragm, and a conductor on at least one face of said second diaphragm, said conductor including at least one conductor strip portion extending parallel to the general direction of said parallel conductor strip portion of said conductor on said corrugated diaphragm.

Claim 13

An audio transducer comprising: a corrugated diaphragm, a conductor on at least one face of said corrugated diaphragm, said conductor having a plurality of spaced parallel series-connected conductor strips, a fixed permanent magnet structure spaced from said at least one face of said corrugated diaphragm, the magnetic field from said permanent magnet structure having a part extending orthogonally of said parallel conductor strips and lying substantially in the general plane of said corrugated diaphragm, a backing plate supporting said fixed permanent magnet structure, said backing plate being perforated at least in the region between adjacent magnets of said structure, a second diaphragm between said fixed magnet structure and said corrugated diaphragm, and spaced therefrom, means holding said second diaphragm in tension applied perpendicularly with respect to said corrugations of said corrugated diaphragm, and a conductor on at least one face of said second diaphragm, said conductor including at least one conductor strip portion extending parallel to the general direction of said parallel conductor strip portion of said conductor on said corrugated diaphragm.