| 摘要 |
PCT No. PCT/EP88/00819 Sec. 371 Date May 9, 1990 Sec. 102(e) Date May 9, 1990 PCT Filed Sep. 9, 1988 PCT Pub. No. WO90/02672 PCT Pub. Date Mar. 22, 1990.A detonation circuit for an inflation capsule (10) of a vehicle air bag has a capacitor (20) which supplies energy to the capsule during a crash condition. The circuit has a transformer (12), the energy source (20) being electrically connectible to the primary coil (P) thereof by two transistors (30, 48) which assume a conducting state when associated control means (16, 18) determine that a crash condition has occurred. Only when both transistors conduct can the energy source (20) cause a change in the current flow through the primary coil (P), which in turn induces a change in current in the secondary coil (S) to which the capsule (10) is connected. It has been found that by monitoring the voltage and current characteristics in the primary coil (P), the state of the capsule (10) can be monitored. For example, it can be determined whether the capsule has fired, and if so further firing pulses may be suppressed.
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