Pushbutton keyboard switch assembly having individual concave-convex contacts integrally attached to conductor strips

A keyboard system comprising an electrically insulative substrate board of a molded synthetic resin material having a plurality of parallel grooves in one surface thereof extending in one direction of the board, a plurality of actuating elements arranged in an array of columns and rows on said one face of the board with said columns extending substantially in said one direction, a plurality of conductors received by said grooves, one conductor in each groove, there being one conductor for each row of said elements constituting a row conductor and one for each column of said elements constituting a column conductor, each of said column conductors being substantially aligned with the center portion of each of the elements in that column, each of said elements comprising a concave-convex disk of flexible electrically conductive material, each said row of elements comprising a series of said disks in line with one another and electrically connected to an electrically conductive carrier on each side of the line of disks, each said line of disks and said carriers secured thereto constituting a unitary strip, each disk in said strip having its concave face toward said board and being movable independently of one another from an initial convex position in which the center portion of the disk is clear of its respective column conductor to a partially over-center actuated position in which the center portion of the disk is in electrical contact with its respective column conductor, said carriers being electrically common to all of said disks in its respective strip, one of said carriers of each said strip being electrically connected to a respective row conductor, a plurality of recesses in said board arranged in an array corresponding to said array of actuating elements, there being one disk for each recess, a first insulative sheet interposed between said board and said strips for electrically insulating said strips and said disks from said conductors, said sheet being secured to said board and having an array of openings therein corresponding to said array of elements, said openings being smaller than said disks so that the outer periphery of the disks are engageable with said sheet, said center portions of the disks being received by said openings thereby to enable the disks to make contact with their respective conductors as they are moved from their initial positions into their actuated positions, and a second sheet of flexible insulative material overlying said strips, said second sheet being adhesively secured to the outer face of said strips and to said first sheet for electrically insulating the strips and for sealing the disks relative to the board thereby to substantially prevent contamination of the electrical contact between said disks and their respective column conductors.