Audio driver and method for transforming an electrical signal into air movement

摘要

An electromagnetic transducer for sound and ultrasound reproduction includes a substantially flat coil coupled to a diaphragm that is near to and facing the North or South side of a magnet. A very thin membrane made from a non-magnetic but electrically conductive material is independently mounted from the diaphragm and faces it. An AC signal in the coil results in diaphragm movement and “modulates” the permanent magnetic field. The modulating field generates a current in the membrane, which, upon further interactions, causes the membrane to move. The two independently moving surfaces each generate sound and result in an unusually flat SPL/frequency response, with unusually low narrow-band intensity variation and very low distortion. The transducer is also unique among electromagnetic transducers in that the force acting on the membrane is uniformly distributed over much of it, as in an electrostatic sound transducer.

主权项

1. An apparatus including a first driver that transforms an electrical signal into air movement, wherein the first driver comprises:
a source of a non-varying magnetic field; a first movable surface, wherein the first movable surface comprises an electrically insulating, non-magnetic material; a coil comprising a substantially flat planar arrangement of an electrically conductive material, wherein the coil is disposed on the first movable surface and the first movable surface is directly driven thereby; a first gap between the source of a non-varying magnetic field and the first movable surface; a second movable surface spaced apart from the first movable surface by a second gap, wherein the second movable surface comprises an electrically conductive, non-magnetic material, and wherein: (a) the second movable surface is not directly driven; (b) the second gap is not sealed; and (c) the air movement results from movement of the first movable surface and the second movable surface.