Patent ID: 7080801

Claim:
A belt retractor for a vehicle safety belt, comprising a rotatably mounted belt spool, a drive wheel coupled coaxially with said belt spool, an electric motor which can drive said drive wheel at a variable drive force, and an electronic control unit which can control said electric motor, said belt spool being relatively rotatable to a limited extent with respect to said drive wheel, and said belt retractor further comprising a sensor that on rotation of said belt spool relative to said drive wheel generates a signal which is indicative of a tensile force acting in said belt and is supplied to said electronic control unit, said drive wheel and said belt spool are coupled with each other by means of a return spring acting in circumferential direction so that a drive force acting on said drive wheel is transmitted to said belt spool, wherein a potentiometer is provided to detect a rotational stroke covered by said return spring on a rotation of said belt spool relative to said drive wheel.