Optical photographic printer for marking keyboard keys - has appropriate characters developed and covered with transparent surface after chemical cleaning

摘要

The keyboard is fitted with new characters in six stages. The surface is firstly cleaned chemically and is covered with a radiation sensitive material. The surface is then exposed to the selected character. The surface is next developed and covered with a transparent protective film. The surface of the key may be flat or concave or convex, and is made of material containing pigments unaffected by radiation. The character is beamed onto the key by an optical instrument which is fitted with a heat filled and a light condenser.