Membrane switch assembly

A switch assembly comprising:

• first circuit means, said first circuit means comprising a flexible planar non-conductive substrate having a conductive circuit pattern supported on at least a first surface thereof;
• second circuit means, said second circuit means including a non-conductive substrate having a conductive circuit pattern supported on at least a first surface thereof, said circuit pattern of said second circuit means facing said circuit pattern of said first circuit means and being at least partly in registration therewith;
• non-conductive spacer means, said spacer means being disposed between said first and second circuit means, said spacer means including at least a first aperture extending therethrough, said aperture being aligned with registered circuit portions of said circuit means whereby electrical contact between registered portions of said said circuit pattern of said first circuit means and said circuit pattern of said second circuit means may be established through said spacer means aperture, said aperture cooperating with said circuit means to define a cavity between said first and said second circuit means;
• and
• self-regulating vent means, said self-regulating vent means preventing establishment of a pressure differential greater than a preselected level between the interior of said cavity and the ambient environment, said self-regulating vent means being activated by the pressure differential between the interior of said cavity and the ambient environment, said self-regulating vent means comprising:
• a non-linear slit, said slit being provided within said first circuit means, said slit forming a flap, said slit being located in the portion of the said first circuit means which defines said cavity.