Abstract: A Hall effect device (60) is exposed to a magnetic field having flux lines extending in a first direction relative to the Hall effect device (60) if a seat belt tongue (16) is not locked in a seat belt buckle (12). The Hall effect device (60) is exposed to a magnetic field having flux lines extending in a second, opposite direction relative to the Hall effect device if the tongue (16) is locked in the buckle (12). The output of the Hall effect device (60) indicates whether or not the tongue (16) is locked in the buckle (12).

Abstract: There is provided an improvement in a seat belt retractor mechanism of the type having a seat belt reel rotatably mounted in a support frame adapted to be assembled on a movable door of a vehicle, wherein the reel has at least on one end a generally circular ratchet plate for engaging a locking element movably mounted on the support frame between a first position allowing the reel to payout the belt freely and a second position engaging the ratchet plate to hold the reel against rotation to payout the seat belt. An inertia sensing element carried by the support frame shifts this locking element into the locked position upon being moved by inertia forces caused by rapid acceleration or deceleration of the vehicle to which the mechanism is mounted. In addition, an electromagnet is employed for increasing the amount of inertia force needed to move the inertia sensor element during such rapid changes in speed of the vehicle.

Abstract: A fluid level sensor utilizes thick film thermistors in a four-thermistor bridge configuration. The bridge is heated by a heater to sense the presence or absence of fluid at a particular level with respect to the thermistors. Upon energizing the bridge with a power source, the middle leads thereof are monitored for voltage separation and polarity. An indicator circuit indicates when one or more of the thermistors is submerged in the fluid. The heater influences the temperature of the thermistors to a greater or lesser extent depending upon whether or not they are submerged. Detectable changes in voltages across the bridge are accordingly produced.