Touch screen with oscillating loop guided elastic waves.

摘要

The touch screen with guided elastic waves comprises a plate (100), a transducer device (10) for emitting elastic waves in parallel zones (X1 to X4) of the plate (100), and a transducer device (30) for receiving elastic waves comprising several independent elementary receiver transducers (31 to 34). Electronic means of exciting the emission device (10) and electronic means of processing the signals delivered by the reception device (20) comprise an amplifier (110) for powering the emission device (10), and a multiplexer (130) for successively connecting each elementary receiver transducer (31 to 34) to the input of the amplifier (110). The gain of the amplifier (110) is chosen so as to create successively closed oscillating loops with several delay lines defined between the emission device (10) and the reception device (30) by zones (X1 to X4) of the plate (100), and means are provided for detecting an absence of oscillations (4) in the successively formed loops and for thereby identifying a zone (106) having been contacted by a finger. <IMAGE>