Audio speaker and proximity sensor with piezoelectric polymer technology

Abstract

A mobile device includes one or more piezoelectric polymer layers underlying a display. The one or more piezoelectric polymer layers may be electrically driven to operate in either a d33 stretching mode or a d31 bending mode. The mobile device functions as an ultrasonic sensor in the d33 stretching mode and as an audio speaker / microphone or a proximity sensor in the d31 bending mode. The piezoelectric polymer layer operating in the d31 bending mode may be directly mechanically coupled to a display, indirectly mechanically coupled to the display and underlying an ultrasonic sensor stack, or integrated in the ultrasonic sensor stack. Signal performance of the piezoelectric polymer layer operating in the d31 bending mode may be enhanced or modulated by having a larger area, multiple layers, bi-pole or uni-pole driving with multiple layers, one or more stiff adhesives, a spacer layer, one or more mass features, a thin TFT layer, a thick piezoelectric polymer layer, or combinations thereof.