KEY ASSEMBLY DIAPHRAGM SWITCH ACTUATOR WITH OVERTRAVEL AND FEEL MECHANISMS

A key assembly for actuating a diaphragm switch, and including a housing, a keystem movably mounted on the housing, and a switch actuator coupled to the keystem through a lost-motion connection arranged so a relatively large stroke of the keystem is required to effect a small actuator motion needed to operate the switch. A coil spring biases the keystem away from the housing to an extended position in which the switch is not actuated, and a second coil spring urges the actuator away from the keystem. The lost-motion connection between the keystem and actuator provides positive retraction of the actuator during the return stroke of the keystem. A leaf spring on the keystem rides a cam surface or ramp on the housing, and the ramp is shaped to modify the effect of the coil springs such that the keystem tends to toggle past the point of switch actuation to prevent switch jitter and to provide a tactile signal that actuation has occurred.