Keyboard switch assembly

DETAILED DESCRIPTION The above-discussed and other deficiencies of the prior art are overcome or significantly reduced by the present invention.
In accordance with the present invention, a keyboard switch array is formed in a sheet of insulating material having conductive circuitry formed thereon.
The conductive circuitry will be referred to as "printed circuitry", but it will be understood that the circuitry may be formed by either printed circuit techniques or any other technique known in the art, such as, for example, conductive inks or die stamping.
The switch elements in this insulating or switch sheet are in the form of an array of protrusions, each of which has a flat top.
The conductive patterns conform to the shape of the flat topped protrusions and are located on the bottom side of the protrusions, i.
e.
the side opposite to the side to which the actuating force is applied.
In the preferred keyboard configuration, this switch sheet is firmly secured relative to a stiffener or backing board, and the switches are actuated by an array of hinged keys integrally formed in an upper layer of the keyboard assembly.
The actuating force of the hinged keys is delivered to the individual switch protrusions at a position off center of the protrusions, and the resultant effect is a very distinct and pronounced snap action and tactile feedback to the key operator.
The switches of the switch sheet cooperate with another layer of conductive patterns on a second insulating layer or sheet to complete electrical circuits when the individual switches are actuated.
The second sheet with its layer of conductive patterns will normally be flat and will have the conductive patterns facing and aligned with the conductive patterns on the switch sheet.
The two sheets are separated by an insulating layer having an array of apertures through which the individual switches move with their snap action effect to make contact between the conductive patterns on the two layers.
The second insulating layer may be a rigid insulating board with printed circuitry thereon, or it may also be a flexible insulating sheet with printed circuitry which would be backed by a stiffening board