Push button switch using dome spring and switch element thereof

Abstract

A push button switch employing a dome spring switch element mounted in a vertical orientation relative to a generally horizontal orientation of a bottom support plate, and a key top and associated plunger which are mounted for limited, reciprocating vertical movement. An actuator, comprising a coil spring and a pivotally mounted lever, interconnects the plunger and the spring dome and is responsive to and converts vertical downward movement of the plunger to a horizontally directed depressing force on the dome spring for inverting the dome spring in a snap action and completing an electrical connection between inner and outer contacts mounted within the switch element and underlying the dome spring. A dome spring of rectangualr shape affords improved force versus displacement and snap action characteristics, and a contact frame providing flexible support of the inner contacts reduces impact shock and wear produced by the snap action. A locking structure provides for locked interengagement of the key top and plunger and a stepped, flexible stop absorbs shock and reduces impact noise in stopping the return movement of the plunger from a depressed to a normal condition. A direct drive connection between the plunger and the lever reduces the amount of plunger movement and depression force required to actuate the switch under abnormal load conditions. A process for fabrication of the switch element by stamping and molding steps reduces costs and improves reliability of the switch element.