Patent ID: 7400737

Claim:
A directional acoustic transducer comprising: a supporting substrate; at least two electrodes formed in said substrate; at least two movable diaphragms, each diaphragm being positioned over a corresponding electrode and including an indentation to maintain a fixed distance between said diaphragm and said diaphragm's corresponding electrode when a bias voltage is applied between said diaphragm and the corresponding electrode, each said electrode including a plurality of holes to allow air in a gap between the electrode and its corresponding diaphragm to escape, thereby reducing acoustical damping therein; a plurality of suspension structures formed on the substrate and attached to the diaphragms to support the diaphragms, the suspension structures supporting each diaphragm having a restoring force equal to or greater than surface contact forces between said diaphragm supported by said suspension structures and the supporting substrate, whereby an electrostatic force associated with the bias voltage overcomes the restoring force of said suspension structures, causing the corresponding diaphragm to be pulled towards the supporting substrate; and a support beam formed in the supporting substrate for providing a flexible mechanical coupling between said movable diaphragms, whereby the response of each diaphragm to incoming sound pressure waves not in phase with one another will be determined by the mechanical interaction between the diaphragms provided by the mechanical coupling beam.