Multitouch Touchscreen Using Reverberant Lamb Waves

Touchscreen sensors are widely used in many devices such as smart phones, tablets, laptops, etc., with diverse applications. We present the design, analysis, and implementation of an ultrasonic touchscreen system that utilizes interaction of transient Lamb waves with objects in contact with the screen. It attempts to improve on the existing ultrasound technologies, with the potential of addressing some of the weaknesses of the dominant technologies, such as the capacitive or resistive ones. Compared to the existing ultrasonic and acoustic modalities, among other advantages, it provides the capability of detecting several simultaneous touch points, and also a more robust performance. The localization algorithm, given the hardware design, can detect several touch points with a very limited number of measurements (one or two). This in turn can significantly reduce the manufacturing cost.