公开(公告)号：EP1644905A4

公开(公告)日：2011-10-26

申请号：EP04776790

申请日：2004-06-16

申请人： ILLINOIS TOOL WORKS

发明人： KNOWLES TERENCE J ,  KALMUS CHRIS

IPC分类号： G01N29/04 ,  B64D15/20 ,  G01M7/00 ,  G01N29/00 ,  G01N29/02 ,  G01N29/22 ,  G01N29/34 ,  G01N29/44 ,  G01W1/00 ,  G08B20060101 ,  G08B19/02 ,  H04B1/02 ,  H04R17/00

CPC分类号： B64D15/20 ,  G01N29/11 ,  G01N29/22 ,  G01N29/34 ,  G01N29/4427 ,  G01N2291/023 ,  G01N2291/0251 ,  G01N2291/02827 ,  G01N2291/0422 ,  G01N2291/0426 ,  G01N2291/0427 ,  G01N2291/044 ,  G01N2291/105

公开(公告)号：EP1642260A4

公开(公告)日：2007-08-08

申请号：EP04754673

申请日：2004-06-02

申请人： ILLINOIS TOOL WORKS

发明人： KNOWLES TERENCE J ,  WEHRER WAYNE J ,  KALMUS CHRIS ,  BRENIGAN III CHARLES F

IPC分类号： G06F3/033 ,  H01H13/83 ,  H03K17/96

CPC分类号： G06F3/0436 ,  H01H13/83 ,  H01H2239/054 ,  H03K17/96 ,  H03K2217/96011

摘要： A circuit for an acoustic wave switch or sensor (10) having a resonant acoustic wave cavity detects a touch or sensed event using a time domain approach. The circuit includes a controller that drives an acoustic wave transducer (12, 12’) to generate a resonant acoustic wave in the acoustic wave cavity (14, 14’) during a first portion of a sampling cycle. In a second portion of the sampling cycle, the controller (30) monitors the time that it takes for the acoustic wave signal from the transducer to decay to a predetermined level, based on the decay time, the controller detects a sensed event, such as a touch on the acoustic wave switch/sensor.