Keyboard switch assembly with multilayer, coextensive contactor means

Claim 2

A keyboard assembly including in combination an electrical circuit board having contact elements, a separator insulator layer positioned over said circuit board, said separator insulator layer having openings registerable with portions of said contact elements, the improvement being a composite contactor positioned over said separator layer for movement through each of said openings to contact said contact elements said contactor comprising a nonconductive resilient, flexible, elastomeric layer supporting an electrically conductive nonelastomeric and non-selfsupporting flexible plastic layer adhered thereto and coextensive therewith for movement therewith, said non-conductive layer being greater in thickness than said conductive layer and said conductive layer having a volume resistivity of about or less than 10 ohm centimeters, and said conductive layer being positioned directly over said openings.

Claim 3

A keyboard assembly according to claim 1 in which the conductive layer is less than 1.969 mil in thickness and in which the elastomeric layer is between 5 to 200 mils in thickness.

Claim 4

A keyboard assembly according to claim 2 in which the conductive layer has silver particles dispersed therethrough.

Claim 5

In a keyboard according to claim 1 in which the conductive layer is 0.197 mil to 1.0 mils in thickness.

Claim 6

In a keyboard according to claim 4 in which the elastomeric layer is 5 to 200 mils in thickness.

Claim 7

In a keyboard according to claim 1 in which the conductive layer is of a lesser thickness than the non-conductive elastomeric layer with the elastomeric layer being of a thickness sufficient and at least about 5 times that of the conductive layer to provide the elasticity to pull the conductive layer back with it after being depressed and the conductive layer being thick enough to provide electrical conductivity.

Claim 8

In a keyboard according to claim 6 in which the volume resistivity is less than 10 ohm cm.

Claim 9

In a keyboard according to claim 7 in which the volume resistivity is less than 1 ohm cm.

Claim 10

In a keyboard according to claim 8 in which the volume resistivity is less than 0.5 ohm cm.

Claim 11

In a keyboard according to claim 1 said conductive plastic layer comprises a plastic binder and electrically conductive particles dispersed therethrough.

Claim 12

In a keyboard which includes an insulator board having circuit pathways thereon, insulator means having a plurality of windows therethrough in alignment with selected portions of the pathways, composite contactor means positioned on the insulator layer and covering said windows of said insulator layer, said contactor means comprising an elastomeric layer having a thinner, flexible non-elastomeric electrically conductive plastic layer physically adhered thereto and coextensive therewith, said conductive layer positioned over at least one of said windows, and pressure application means for forcing said composite contactor through said windows to cause said conductive layer to electrically contact portions of said pathways, said elastomeric layer being thick enough to keep said conductive layer away from said pathway portions in the absence of pressure applied to pressure application means and for pulling said conductive layer away with it from said pathways after application of pressure to said pressure application means, and said conductive layer being thick enough to provide electrical conductivity while not being so inflexible to separate from the elastomer upon being flexed in continuous use.

Claim 13

In a keyboard which includes an insulator board having circuit pathways thereon, insulator means having a plurality of windows therethrough in alignment with selected portions of the pathways, composite contactor means positioned on the insulator layer and covering said windows of said insulator layer, said contactor means comprising an elastomeric layer having a thinner, flexible non-elastomeric electrically conductive plastic layer physically adhered thereto and coextensive therewith, said conductive layer positioned over at least one of said windows, and pressure application means for forcing said composite contactor through said windows to cause said conductive layer to electrically contact portions of said pathways, said elastomeric layer being thick enough to keep said conductive layer away from said pathway portions in the absence of pressure applied to pressure application means and for pulling said conductive layer away with it from said pathways after application of pressure to said pressure application means, and said conductive layer being thick enough to provide electrical conductivity while not being so inflexible to separate from the elastomer upon being flexed in continuous use.

Claim 14

In a keyboard according to claim 11 in which the conductive layer is 5 to 100 microns in thickness.

Claim 15

In a keyboard according to claim 12 in which the elastomeric layer is 10 to 100 mils in thickness.

Claim 16

In a keyboard according to claim 11 in which the conductive layer is of a thickness less than 1 mil.

Claim 17

In a keyboard according to claim 14 in which the conductive layer is of a thickness less than 0.788 mil.

Claim 18

In a keyboard according to claim 4 in which the conductive layer comprises polyamide adhesive resin having silver particles dispersed therein.

Claim 19

In a keyboard according to claim 4 in which said conductive plastic layer comprises a plastic binder and electrically conductive particles dispersed therethrough.