Fully illuminated backlit membrane touch switch

Claim 1

A backlit membrane touch switch panel comprising: an insulating board having a hole for receiving a light source and having a pair of contacts with a gap between them disposed on the nominally top surface of said board adjacent said hole, a thin insulating spacer sheet arranged with its bottom surface facing said board, said spacer sheet having an aperture aligned with said contacts, an insulating flexible membrane having a hole aligned substantially with the hole in said board and arranged with its bottom surface facing the top surface of said spacer sheet, said membrane having a thin contact disposed on its bottom surface and aligned with said spacer aperture, said contact becoming engageable with said pair of contacts to bridge said gap when said membrane is pressed and flexed through said aperture, said membrane restoring to its unflexed condition when it is not pressed, a rigid plate member arranged with its bottom surface in substantial parallelism with said membrane and spaced from said membrane, said plate member having an aperture that aligns substantially with said aperture in said spacer sheet, means for maintaining said plate member at a fixed spacing from said membrane, a rigid combination switch plunger and light channel element having its nominally upper end loosely fit in said plate aperture and its lower end bearing on said membrane in the vicinity of the contact on its bottom, a film having its bottom surface interfaced with the top surface of said plate member and having a translucent zone disposed over said plunger and light channel element such that force produced by touching said zone will be transmitted by said element to flex said membrane and cause said contacts to engage, and a lamp and a socket for the lamp, said socket having exposed contacts extending from it and leading to said lamp, said socket having means for interlocking it with said board and said socket holding lamp for it to extend into said combination light channel and plunger element, said exposed socket contacts engaging respectively with said contacts on the bottom surface of the board when said socket is interlocked.