Patent ID: 11460957

Abstract:
An ultrasonic sensor includes a two-dimensional array of ultrasonic transducers, a contact layer, a matching layer between the two-dimensional array and the contact layer, where the matching layer has a non-uniform thickness, and an array controller configured to control activation of ultrasonic transducers during an imaging operation for imaging a plurality of pixels within the two-dimensional array of ultrasonic transducers. During the imaging operation, the array controller is configured to activate different subsets of ultrasonic transducers associated with different regions of the two-dimensional array of ultrasonic transducers at different transmission frequencies, where the different frequencies are determined such that a thickness of the matching layer at a region is substantially equal to a quarter wavelength of the first transmission frequency for the region. The array controller is also configured to combine the plurality of pixels into a compound fingerprint image that compensates for the non-uniform thickness of the matching layer.