Apple Inc.
METHOD AND APPARATUS FOR ISOLATING ULTRASONIC TOUCH SENSOR FROM REFLECTIONS IN A DEVICE HOUSING

Abstract:

Acoustic touch sensing system architectures and methods for acoustic touch sensing can be used to detect a position of an object touching a surface. Acoustic touch sensing can utilize transducers (e.g., piezoelectric) to simultaneously transmit ultrasonic waves along a surface and through a thickness of a material. The location of the object can be determined based on the amount of time elapsing between the transmission of the waves and receipt of the reflected waves. In some examples, an acoustic touch sensing system can be insensitive to water contact on the device surface, and thus acoustic touch sensing can be used for touch sensing in devices that may become wet or fully submerged in water. In some examples, techniques such as isolation and absorption of acoustic energy can be used to mitigate acoustic energy reflected by portions of the electronic device and interfere with the acoustic touch sensing operation.