A membrane switch (10) having a top membrane (12) with a lower conductive surface (16), a bottom membrane (14) with an upper conductive surface (18), and a dielectric intermediate circuit spacer (20) disposed therebetween. The intermediate circuit spacer includes a central aperture (24) and defines upper...http://www.google.de/patents/US5228562?utm_source=gb-gplus-sharePatent US5228562 - Membrane switch and fabrication method
