Acoustic touch position sensor using a low acoustic loss transparent substrate

Abstract

An acoustic touch panel or “touch screen” utilizes acoustic waves within a sensor substrate to determine the position of touch. The substrate is made of a temperable glass having an attenuation coefficient of less than or equal to about 0.6 dB/cm as determined at the substrate surface for 5.53 MHz Rayleigh waves as measured by the slope of a plot of amplitude versus distance for a signal through a pair of facing 0.5-inch wide wedge transducers mounted on a sample of the glass type under test having sufficient thickness to support Rayleigh wave propagation. An acoustic touch panel with a tempered low-acoustic-loss glass substrate. This makes possible large tempered acoustic touch panels. A glass substrate of the touch sensor comprises SiO2 as the main component with a total content of Na2O, CaO and MgO of 20% by weight or less and a total content of Al2O3, ZrO2, TiO2, B2O3, Y2O3, SnO2, PbO2, In2O3 and K2O of 5% by weight or more.

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