Patent ID: 7229054

Claim:
A mechanism, comprising: (a) a shaft; (b) a taper sleeve, which has an outer spiral line on the upper part of the taper sleeve and an out gradient slope on the lower part of the taper sleeve and a number of slots which are equipped on the lower part of the taper sleeve, forming a number of circular section plates, on each circular section plate exists a square hole, a plastic plate is inserted inside the square hole and the plastic plate is covered with a ramp plate, the inner gradient slope of the central tube moves downwards to press outer gradient slopes of the ramp plates in the square holes of the circular section plates of the taper sleeve, and pushes the ramp plate to compress the plastic plates onto the shaft, when the central tube moves downwards by rotation, as to fix the vertical position of the support frame; (c) a support frame with a central tube, the central tube is equipped at the central part of the support frame, the central tube has an inner spiral line matching with the outer spiral line of the taper sleeve and an inner gradient slope matching with the outer gradient slope of the taper sleeve.