A low-profile, full-travel computer keyboard comprising:
- a key support member having an array of upstanding keystem receiving elements at key locations, in which each of the upstanding keystem receiving elements has an upright wall with a central bore defining an upright key axis;
- a plurality of keys supported by the key support members at the key locations, in which each of the plurality of keys has a keystem with a central plunger that is slidably supported in a central bore of one of the upstanding keystem receiving elements to enable each of the plurality of keys to move in a full-travel stroke along the upright key axis between a low-profile rest position and a keyswitch actuation position;
- a plurality of rubber dome return springs mounted on the key support member and engaging the plurality of keys for biasing the plurality of keys to their low-profile rest position;
- a keyswitch membrane mounted on the key support member with the plurality of key support members extending up through corresponding plurality of membrane apertures formed in the keyswitch membrane at the key locations, with each of the plurality of membrane apertures aligned with a corresponding one of the key axes;
- said keyswitch membrane having a plurality of membrane keyswitches, with each of the plurality of membrane keyswitches being associated with one of the key locations circumscribing at least in part one of the plurality of upright keystem support walls;
- each of the plurality of membrane keyswitches having (1) a lower membrane layer with a first arcuate electrical circuit trace printed on a top surface thereof at one of the key locations, and (2) an upper membrane layer spaced from the lower membrane layer with a second arcuate electrical circuit trace printed on a bottom surface in contact alignment with the first arcuate electrical circuit trace at said one of the key locations;
- each of the plurality of membrane keyswitches having a plurality of elongated, radially oriented, angularly spaced dielectric pads covering spaced non-contact segments of one of said arcuate electrical circuit traces opposing uncovered intermediate contact segments;
- wherein each of said dielectric pads has a thickness sufficient to maintain the upper membrane layer spaced from the lower membrane layer to prevent the second electrical circuit trace from contacting the first electrical circuit trace when the key is in the rest position;
- each of the plurality of membrane keyswitches having a plurality of elongated, radially oriented, angularly spaced stress concentration pads printed on a top surface of the upper layer angularly spaced intermediate the dielectric pads and in alignment with the uncovered intermediate contact segments of said one electrical circuit trace;
- and
- a keyswitch actuator at each of the key locations that is responsive to the movement of one of the keys from the rest position to the actuation position for engaging the stress concentration pads to deflect the uncovered segments of the upper membrane layer downward into contact engagement with the first electrical circuit trace of the lower membrane layer to activate the keyswitch.