Signal push button fitted into wall of instrument casing - is mounted in opaque bushing and pref. consists of transparent PMMA

摘要

Signal knob protruding from the front wall of an appts. has an axially displaceable signal portion with transparent head section with reflex element at the rear end, which, when the signal portion is in "forward" position with transparent head section protruding from the appts. wall, reflects any laterally incident light forward. There is a transparent colour element for emphasising the forwards-reflected light. The signal portions is located in a dark-coloured, opaque, sleeve in which it is entirely encased when pushed back. It consists, at least in its forward section, of clear transparent plastics, esp. PMMA.