| 摘要 |
<p>PROBLEM TO BE SOLVED: To easily detect whether an occupant is seated on a seat or not by detecting an electric current flowing in a transmission signal system by an electric current detection circuit. SOLUTION: A weak electric field is produced in accordance with high frequency low voltage supplied to an antenna electrode 5 from an oscillating circuit 21 in a periphery of the antenna electrode 5, and an electric current flowing in accordance with this weak electric field differs in accordance with an object existing on a seat 1B. Additionally, a phase difference between a transmission signal from the oscillating circuit 21 and an output signal to the antenna electrode 5 on the side of the oscillating circuit 21 and the side of the antenna electrode 5 of an electric current detection circuit 25 also differs in accordance with the object existing on the seat 1B. Especially, in the case when the object is a human, it has a phase difference of a level in a degree free to recognize in comparison with other objects. Consequently, it is possible to highly precisely detect whether an occupant is seated on the seat 1B or not easily as well as to judge it with a signal data in connection with a detected electric current by detecting the phase differences by a phase difference detection circuit 29.</p> |
