Stack key structure and balance-shaft seat thereof

A key structure, comprising:

• a switch shaft sleeve seat;
• a switch shaft accommodated in the switch shaft sleeve seat, wherein a top end of the switch shaft penetrates a top of the switch shaft sleeve seat and is movable relative to the switch shaft sleeve seat;
• two balance shaft sleeve seats arranged on two sides of the switch shaft sleeve seat, wherein each of the balance shaft sleeve seats comprises a sleeve body, a side of each of the sleeve bodies comprises an adjacent side edge arranged adjacent to the switch shaft sleeve seat, and a top of each of the sleeve bodies comprises a through hole located in the middle of the adjacent side edge, each of the through holes defines a central axis and a minor axis plane and a major axis plane intersecting at the central axis, wherein the minor axis planes are arranged perpendicular to the adjacent side edges, the major axis planes are arranged perpendicular to the minor axis planes, and an appearance of each of the sleeve bodies is symmetrically set with the minor axis plane as a reference and asymmetrically set with the major axis plane as a reference;
• two balance shafts respectively disposed in the sleeve bodies, wherein top ends of the balance shafts penetrate the through holes;
• and
• a key cap arranged above the switch shaft sleeve seat and the two balance shaft sleeve seats and fixedly connected to the switch shaft and the two balance shafts.