ACOUSTIC TOUCH POSITION SENSOR USING HIGHER ORDER HORIZONTALLY POLARIZED SHEAR WAVE PROPAGATION

摘要

An acoustic wave touch position sensor in which a transducer (14) coupled to asubstrate (10) imparts a surface acoustic wave, into the substrate (10) forpropagation along a first axis. A reflecive array (28, 34, 30, 36) havingselective reflection characteristics for various wave propagation modes isdisposed along the first axis to create a higher order horizontally polarizedshear wave having an order greater than zero perpendicular to the axis, sothat a touch surface (40) of the substrate (10) is imparted with shear waveenergy. This energy may be partially absorbed, attenuated or perturbed by anobject touching the substrate (10), to create a modified waveform having acharacteristic indicative of the axial displacement and/or contact conditionof the object with the substrate (10).