Dual spring actuator for keyboard switch assembly

A keyswitch assembly comprising:

• a substrate having disposed on a surface thereof an electrical circuit defining at least one first switch contact at each of a plurality of switch regions;
• a switch carrier assembly including a plurality of second switch contacts, at least one being disposed at each switch region for switch closure engagement with a first switch contact in response to a switch actuation force;
• and
• a switch actuator assembly disposed to selectively provide a switch actuation force at each switch region, the actuator assembly including for each switch region a follower disposed to engage the switch carrier assembly and transmit a switch actuation force to a second switch contact, the follower having a central aperture for slideably receiving a guide post;
• a key having central aperture with a guide extending therein, the key slideably receiving the follower within the aperture thereof with the guide post being received within the central aperture of the follower;
• a guideway being disposed to receive the key at a position proximate the switch region and to limit key motion between fixed limit points along a single axial direction;
• a first spring disposed in compression between the substrate and the key and tending to maintain the key at a first axial limit position spaced farthest from the substrate;
• a second spring disposed between the follower and the key to apply a minimum force therebetween when the key is at the first axial limit position and a maximum force therebetween when the key is at a second axial limit position spaced nearer the substrate, said second spring force providing the sole coupling force between the key and the follower, the coupling force being sufficient to cause switch closure when the key is at the second limit position and insufficient to cause switch closure when the key is at the first limit position.