Typewriter and calculator key marking system - uses plastic sheet with characters printed in recesses to suit layout cut in position to form caps

摘要

The process enables typewriter and calculator keys to be assembled, without markings, onto the machine, the characters being added to suit the required layout. It comprises a sheet of transparent plastic, printed with the characters in their set order. The sheet (2") is theremoformed to provide several recesses (6) the same shape and size as the keys. The sheet is placed over the unmarked keys, being supported on a plate. A tool, comprising a corresponding number of hollow punches, descends and cuts around the recesses to form caps; at the same time the punches push these over the keys to cover them.