Patent ID: 7521615

Claim:
A string tension adjustment structure, comprising: a dock which has a housing compartment inside and a holding chamber located at one side of the housing compartment, the holding chamber having a pair of insertion troughs and a front wall and a rear wall that have respectively a circular opening opposing each other; a winding axle which runs through the dock from the bottom thereof and has an upper end coupling with a worm gear to be rotated synchronously therewith, the worm gear being held in the housing compartment, the winding axle having a transverse string hole at a lower side to be threaded through by a string of a stringed instrument for fastening; a rotary knob which has a handle at one end and a worm extended from another end to run through the two circular openings of the dock, the worm having two indented necks at a front side and a rear side thereof and being engaged with the worm gear; and a U-shaped elastic reed which is wedged in the insertion troughs of the holding chamber and has a pair of clipping blades extended upwards from a front side and a rear side thereof that are formed in an arched convex fashion directing inwards with the a top edge extended outwards, each of the clipping blades having a notch at an upper side to clip the indented neck of the worm.