Patent ID: 7731137

Claim:
A vertically adjustable supporting structure comprising: a link member whose bottom and top portions are disposed with a lower end and a top end; a lower hinge having a respective fixed shaft pivoted on the lower end of the link member so as to render the link member rotatably pivoted between two lower frames of the lower hinge; an upper hinge having at least one respective movable shaft pivotally connected on the upper end of the link member so as to render the link member rotatably pivoted between two upper frames of the upper hinge; at least a coupling assembly having one lower axle wheel and one upper axle wheel disposed between the lower end and the upper end of one side of the link member and between the lower frame and the upper frame, respectively, and pivoted on the lower hinge and upper hinge, respectively, with a flexible cord engagingly secured between the lower and upper axle wheels; and at least an idle wheel pivoted on one side of the link member and between the lower and upper axle wheels to be interlacingly engaged with the flexible cord and to form a coupling movement, such that the coupling assembly transforms a circular movement of the link member into a rotation for compensating displacement difference of the two upper frames without affecting their original angle.