US Patent 7523672 Collapsible force sensor coupling

A force sensor particularly suited for use in an electronic stylus that senses the contact force on its nib for recording pen strokes and handwriting recognition. The sensor has a housing for a load beating member for receiving an input force to be sensed and associated circuitry for converting the input force into an output signal indicative of the input force. A coupling transmits the input force to the load bearing member. The coupling has an inner section for transmitting the input force to the load beating member, an outer section for receiving an applied contact force and a collapsible section for allowing the outer section to move relative to the inner section when the contact force exceeds a threshold. This protects the force sensor from damage by sharp impact loads such as dropping the stylus on its nib.