The present invention relates to switch technology, and more particularly capacitive switch technology for switching fractional ampere current with an actuator that can provide a tactile feedback snap action in response to a push-to-actuate type of operation. Switches of this type are particularly desirable where low cost, compact size and minimal protrusion from a panel are desired. Cellular phone keypads are a typical application of such desired switch type action.
Capacitance change type switching technology has been most commonly used for smooth panel switches where the user touches a laminate on the panel to effect a change in capacitance between two plates. The change is detected by appropriate circuity and discerned as a switching operation. Combining such capacitive switching technology with an actuator that provides a tactically discernible indication of movement similar to the switching of a mechanical contact type switch is disclosed in U.S. Pat. No. 5,559,665, wherein a spring biased movable actuator is employed to effect compression of a resilient conductive disk in contact with a dielectric material for effecting a discernable capacitance change. However, the push-button type actuator assembly disclosed in this patent includes an undesirable number of parts with attendant increased costs therefor. Accordingly, there is a need for a simpler, lower cost switch assembly capable of functioning as a low current switching element that can provide tactile feedback from actuator movement during the switching operation to allow a user to recognize the switching. Such an assembly has particular applicability to automotive environments wherein switch operation can frequently occur without need for visual perception such as heating and cooling blower fan controls. Other possible uses are window or door lock switches on a car door arm rest.
The present invention contemplates a new and improved capacitive switch technology which overcomes all the above-referred to problems and others to provide a new capacitive switch assembly which is simple in design for improved parts consolidation and cost reduction, economical to manufacture, readily adaptable to a plurality of uses in a variety of dimensional configurations, easy to install, easy to operate and which provides improved switching operation in an environment such as an automobile.