Triggering circuit for a safety device in motor vehicles

Claim 1

Apparatus for activating a safety device in a motor vehicle upon impact of said motor vehicle; comprising: a first triggering path having a first acceleration sensor and digital processing means for analyzing a signal from said first acceleration sensor to produce a first output signal when said signal from said first acceleration sensor exceeds a first predetermined threshold value; a second triggering path having a second acceleration sensor and analog processing means for analyzing a signal from said second acceleration sensor to produce a second output signal when said signal from said second acceleration sensor exceeds a second predetermined threshold value; switch means coupled to receive said first and second output signals, for activating said safety device in response concurrent existence of said first and second output signals; said first triggering path being calibrated to respond to an impact later than said second triggering path, and thereby controlling timing of activation of said safety device; and said apparatus further comprising a pulse generator coupled to provide sequential test pulses to said first and second triggering paths in response to control signals generated by said digital processing means, and means for preventing said pulse generator from providing a test pulse to said first triggering path during existence of an output signal from said second triggering path.