A process for the preparation of a keycap for illuminated push button switch

摘要

A method of preparing an elastomeric keytop (e.g. for a membrane keyswitch) of the kind which has an indicium which can be backlit from below, said method comprising: (i) moulding an outer surface shell of the key from an opaque elastomeric sheet (Fig. 1a) (ii) filling the interior keyhead of the shell with non-opaque coloured curable material, and at least partially curing said material (Fig. 1b) (iii) completing structural moulding of the key with additional transparent material (15) (Figs. 1c and 1d) (iv) ablating an indicium through the opaque top of the keyhead (e.g. by laser exposure through a mask) (Fig. 1e) (v) attaching a conductive switch element (7) (Fig 1f). The key may be moulded from silicone rubbers, and the outer shell may be formed from a compsite sheet comprising a cured layer and an uncured layer. IMAGE