Transparent switch having fine line conductors

A membrane switch assembly comprised of two layers of substantially transparent film having internal surfaces that are separated from each other by spacing means, the spacing means having openings therein constituting switch sites, the internal surfaces of each layer having electrodeposited hairline conductors thereon, the conductors crossing and being normally spaced from each other at the switch sites, the assembly being characterized in that:

• the internal surface of the first layer has a plurality of electrodeposited spaced-apart parallel double hairline conductors, each double conductor having a first portion, an intermediate portion, and a second portion, the first and second portions of the double conductor being essentially parallel to each other, with the intermediate portion connecting the first and second portions, the distance between the first and second portions of each double conductor being less than the distance between adjacent conductors,
• the internal surface of the second layer has a plurality of spaced-apart parallel double hairline conductors electrodeposited in a direction normal to the direction of the first layer conductor, the first sites being created by the crossing double hairline conductor of the first and second circuit layers when they are assembled, thus giving four points of contact at each site,
• the spacing means is a polymer spacer comprised of an insulating ultraviolet curable polymer applied in parallel strips over the conductors, the polymer spacer being discontinuous at the switch sites, whereby,
• as force is applied at the switch site to bring the two layers of conductors together, an electrical circuit can be completed at any one of four crossing locations thus providing redundancy and insuring the completion of the electrical circuit even if the force has been applied at the periphery of the switch site.