To improve visibility of a key top by increasing the quantity of light which is transmitted from a core layer to the key top side in the keypad built in an information apparatus such as a portable phone.
A keypad 5 has a core layer 6 which transmits and conducts light in the surface direction. A key top 7 is bonded to one surface of the core layer 6 while interposing an adhesive layer 8 having a refractive index smaller than that of the core layer 6 therebetween. On the other surface of the core layer 6, a diffusion layer 9 corresponding to the key top 7 is formed to face a switch 13. A clad layer 12 having a refractive index smaller than that of the adhesive layer 8 is interposed between the core layer 6 and the adhesive layer 8. Consequently, the critical angle of total reflection on the surface of the core layer 6 can be decreased. As a result, the quantity of light which is transmitted from the core layer 6 to the key top 7 side is increased and visibility of the key top 7 is improved.
IHARA KIYOMICHI
HOTTA SHINJI
KATO KATSUHIKO
KAWAMURA TAKASHI
Akio Ishii