Return spring for tracker ball coding contact, comprises coiled spring which engages with toothed wheel of coding shaft at one end and is secured to containing trough at other end by thermal welding

摘要

A tracker ball is in contact with the drum of a longitudinal shaft and also the drum (42T) of a transverse shaft (32T). The shaft has a toothed coding pinion (44T) which engages with a contact rod (70T) formed from the end of a coil spring (50T). The coil spring lies in a trough (46T) and the the end remote from the coding pinion is anchored by welding using two electrodes (E1,E2) An Independent claim is also included for : A method of fixing a metallic component such as a spring in a trough within a plastic case by thermowelding