Key switch having an actuator integral with the return spring

Claim 1

A key switch assembly of the type comprising a plunger, a return spring, and an actuator, the plunger being movable from an extended position to a depressed position with accompanying flexure of the return spring, the actuator being normally spaced from a switch contact zone and being movable against the contact zone in response to movement of the plunger from the extended position to the depressed position thereby to change the condition of the switch, the return spring being effective to return the plunger to the extended position with accompanying movement of the actuator away from the contact zone, the return spring and the actuator being provided as a one-piece member, the key switch assembly being characterized in that: the one-piece member has a force-receiving portion which is in engagement with the plunger, the return spring extends away from the force-receiving portion along a spiral path to a reaction portion which bears against a fixed support that is proximate to the switch contact zone, the actuator extends away from the force-receiving portion towards the reaction portion, the actuator having a free end and having a contact portion on the free end which is engageable with the switch contact zone, the contact portion being between the force-receiving portion and the reaction portion when the plunger is in its extended position, the return spring extending along a first spiral path from the force-receiving portion, the radius of the first spiral path increasing along at least a portion of the first spiral path, the actuator extending along a second spiral path from the force-receiving portion to a reversed portion adjacent to its free end, the actuator being entirely between adjacent turns of the return spring whereby upon movement of the plunger from the extended position to the depressed position, the return spring is resilienty flexed and the contact portion of the actuator is moved against the contact zone thereby to change the condition of the switch.