To exibit a great effect of cost reduction by the reduction of the number of parts and the simplification of a structure, as a whole or part of a button base plate is formed as a light guide part with transparent resin and the whole of a plurality of push-buttons fitted on the button base plate are brightly illuminated with the number of light sources fewer than the push-buttons.
The button base plate 2 is formed of a transparent member with a hole 2a fitted at a given position of the button base plate and a spring 3 is integrally formed into the hole by a member with a light diffusion agent added in silicone rubber, so that the button base plate 2 is a light guide part capable of propagating light without giving a rise to a loss, and the spring uniformly diffuses light distributed by the light guide part, which enables the lesser number of the light sources 6 to illuminate and enables downsizing and cost reduction.
NISHIMURA TAKESHI
SENSUI AKIRA
HAMADA NAOHITO
POLYMATECH CO LTD