| 摘要 |
PROBLEM TO BE SOLVED: To enable simply precise detection of the drawing-out quantity or the winding-up quantity of a seat belt. SOLUTION: In this detecting apparatus, only the ripple component of a voltage signal (that is, a voltage between terminals of a DC motor 10) which is obtained by subtracting a voltage signal of an IF(interface circuit) 4 from a voltage signal of an IF 3 is taken out by digital filter processing 21, the frequency that the ripple component exceeds a given voltage v0 is counted by a counter process 22, only the ripple component of a voltage signal (that is a voltage between terminals of the DC motor) which is obtained by subtracting a voltage signal of the IF 4 from a voltage signal of the IF 3 is eliminated by digital filter process 24, it is detected whether the DC motor operates in the drawing-out direction of the seat belt or in the winding-up direction, from the polarity of the voltage signal in which only the ripple component is eliminated, by motor rotation direction detecting process, and the drawing-out quantity of the seat belt or the winding-up quantity is calculated by drawing-out and winding-up quantity operating process 23, on the basis of the count value counted by the counter process 22 and the rotation direction of the DC motor detected by the motor rotation direction detecting process 25. |
