Membrane switch having spacer posts

Claim 1

A pushbutton switch in which a movable contact carried on a deformable support member may be contacted with or separated from an opposing fixed contact for closure or opening of the contacts, said pushbutton switch comprising a base portion having a flat upper surface mounting said fixed contact, a pushbutton member having a flat bottom surface mounting said movable contact, a skirt portion of resilient insulating material coupling said pushbutton member to said base portion and being of sufficient height to position said pushbutton member in an open position in which said movable contact is spaced above said fixed contact and in registry therewith, whereby upon manual depression of said pushbutton member, the resilient skirt portion deforms to permit lowering of said pushbutton member to a closed position in which said movable contact engages said fixed contact, said pushbutton member being relatively rigid, whereby said pushbutton member is subject to tilting when manually depressed in a centrally-offset region, and at least one post depending from the flat bottom surface of said pushbutton member and being spaced from and proximate to said movable contact, said post being of lesser height than the thickness of said movable contact and being spaced above said base portion upper surface in the open position of said pushbutton member, said post being made of a material having a high coefficient of friction and being positioned to engage the flat upper surface of said base portion when said pushbutton member is moved to its closed position, whereby to prevent tilting of said pushbutton member relative to said base portion and to retard transverse shifting of said pushbutton member relative to said base portion.