Illuminated instrument knob esp. for automobile or aircraft - has peripheral symbols with thin contrast coating of e.g. ABS

摘要

A method of making an indicator or operator knob, such as particularly a rotatable knob for a channel selector, consists of first making, from a translucent material, a knob optionally having radial incisions; then hot-embossing the projecting symbols around the rim of the knob; then partly covering the rim with an opaque plastics material. Pref. the dye applied during the hot-embossing is so thin that only a partial loss of light results and an optimum contrast effect is obtd. A preferred translucent material is acrylic, esp. having a fusion point of 200-230 deg.C. The opaque plastics material may be ABS, having a fusion point of 180- 220 deg.C. The knob can thus be illuminated from internally due to its translucent properties and is suitable for the dashboard of an automobile or an aircraft.