Fault detecting system for vehicle occupants protective apparatus

Claim 1

In a vehicle occupants protective apparatus having an operation circuit for radiating an electromagnetic wave, receiving the electromagnetic wave reflected from a target body and combining said radiated wave and said reflected wave to generate a detection signal indicative of a vehicle collision, and an actuating circuit, connected to said operation circuit, for actuating an occupants protector means in response to said detection signal, a fault detecting system comprising: a first check circuit, connected to said operation circuit, for applying a pseudo signal of fixed frequency thereto to thereby continuously check an occurrence of a fault of said operation circuit; a second check circuit for checking an occurence of a fault of at least one function of said vehicle occupants protective apparatus; a logical circuit, connected to said first and second check circuits, for generating an indication signal while at least one of the fault occurrences are being detected by said first and second check circuits; an indicator means, connected to said logical circuit, for indicating an occurrence of a fault in response to said indication signal; a timer circuit, connected to said logical circuit, for generating a timer signal representing that duration of said indication signal has exceeded a predetermined time; a storage means, connected to said timer circuit, for memorizing the generation of said timer signal irrespectively of expiration of said timer signal; and a prohibition circuit, connected between said storage means and said actuating circuit, for preventing the operation of said actuating circuit while said storage means memorizes the generation of said timer signal, whereby said occupants protector means is maintained irresponsive to said detection signal while at least one fault exists.