Apparatus for and method of converting from a digital signal to an acoustic wave using a piezoelectric beam

An electroacoustic transducer for converting a serial digital word, of the type having a plurality of bit locations including locations for a polarity bit and a plurality of magnitude bits having at least a most and a least significant bit, into an acoustic signal, the transducer being adapted to convert digitized audio in a time division multiplexed format into an audio acoustic signal comprising:

• a. means for converting the serial digital word into parallel form,
• b. buffer means for converting each magnitude bit into an output voltage of a first polarity when a bit is present in the polarity bit location and for converting each magnitude bit into an output voltage of a second polarity when a bit is absent from the polarity bit location,
• c. a piezoelectric structure including a beam made of a piezoelectric, non-conductive material and having fixed and free ends and first and second side surfaces, a first layer of a grounded conductive material on the first surface of the beam and a second layer of conductive material on the second surface of the beam, the second layer being divided into a plurality of electrically separated segments having substantially equal surface areas, each segment being connected to an output of the buffer means with the segment closest to the fixed end being connected to the output corresponding to the most significant bit and the segment closest to the free end being connected to the output corresponding to the least significant bit, the beam being adapted to have its free end deflected in a direction corresponding to the polarity of the word and at a magnitude corresponding to the magnitude of the word and,
• d. acoustic means connected to the free end for creating an acoustic signal in response to the deflection of the free end of the piezoelectric beam.