Apple Inc.
ANNULAR PIEZOELECTRIC STRUCTURE FOR ULTRASONIC TOUCH SENSING

Abstract:

Acoustic touch sensing systems can include a mechanically integrated structure including multiple acoustic transducers. For example, an annular structure including one or more piezoelectric segments can be fabricated and then coupled to a front crystal/cover glass. A single structure can simplify the structural integration of the device, can provide a mechanically reliable and stable structure for improved structural integrity of the system, and can provide for improved water sealing for a waterproof or water resistant device. The piezoelectric material in the annular structure can be shear poled such that a poling direction of the piezoelectric material can follow the curvature of the annular piezoelectric structure.