Patent ID: 6909278

Claim:
A motion detector including at least one element ( 10 ) moving at least temporarily, a circuit assembly for sensing the motion condition of said element ( 10 ) comprising: at least one sensor located adjoining said element ( 10 ); a timed pulse activated oscillating circuit (L, C) which is variably damped depending on said motional condition of said element ( 10 ); a signal processing circuit (R 1 , R 2 , T, 20 , 22 ) for forming the signals of said oscillating circuit suitable for analysis in an analyzer ( 18 ) receiving and analyzing said signals output by said signal processing circuit (R 1 , R 2 , T, 20 , 22 ), wherein said signal processing circuit (R 1 , R 2 , T, 20 , 22 ) includes a comparator ( 20 ) having an input for application of at least the positive or negative half waves of said oscillating circuit signals and an other input for application of a reference voltage (Vref) and selected so that when said sensor ( 16 ) is activated, the output signal of said comparator ( 20 ) changes its condition depending on how said sensor ( 16 ) is damped by said element ( 10 ).