| 摘要 |
An apparatus for detecting the proper utilization of a safety belt of a vehicle by a vehicle occupant which includes a high frequency oscillator and a sensing foil connected to the oscillator which is positioned in the seat of the vehicle. The oscillator is in a non-oscillating condition prior to the presence of the occupant in the seat, begins to oscillate when the occupant is positioned in the seat due to capacitive interaction between the occupant and the sensing foil in the seat, and stops oscillating upon buckling of the seat belt. Advantageously, the oscillator of the present apparatus has a power supply input impedance of large value so that the apparatus may be connected to the vehicle battery even when the ignition switch is turned off without detrimentally-high battery drain. Consequently, occupants who occupy the seat and fasten the safety belt prior to the closing of the ignition switch will be given credit for such action. This high power supply input impedance which results in low power drain is accomplished without sacrificing the efficiency and detection capability of the system and without sacrificing the protection of the system against voltage transients which may occur during periods of momentary heavy loads such as during the starting of the vehicle.
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