State detection system, for safety belt, monitors belt spool and deployed belt length with illumination and photodetector arrangement, and uses them to assess belt use, static and dynamic load

摘要

The system monitors the belt spool and/or the outgoing belt length with an illumination and photodetector arrangement and uses them to assess the use of the belt and to determine the static and dynamic load. The belt load displaces the belt axis via a spring system; this is detected by a photodetector.