The present invention is directed to a belt tensioning mechanism that is actuated in response to a vehicle deceleration exceeding a predetermined critical value for retracting the belt buckle so as to apply a tension loading on the safety belt for minimizing forward excursions of the seat occupant. The...http://www.google.com.tw/patents/US5364129?utm_source=gb-gplus-share專利 US5364129 - Vehicle safety belt tensioning mechanism
