Piezoelectric dispenser and method of calibrating stroke of the same

A method of dispensing liquid, the method comprising:

• providing a liquid dispenser that comprises
• a nozzle comprising a valve seat;
• a valve rod comprising a tip;
• at least one piezoelectric actuator configured to expand and shrink in response to electric signals,
• a lever operably connected to the at least one piezoelectric actuator and operably connected to the valve rod such that expansion and shrinkage of the at least one piezoelectric actuator cause pivotal movement of the lever about a pivot axis, which in turn causes reciprocation of the valve rod along a first axis,
• wherein the reciprocation of the valve rod involves repeated impacts by the tip of the valve rod on the valve seat of the nozzle, which causes wearing out of at least one of the valve seat and the tip of the valve rod over time,
• wherein wearing out of the at least one of the valve seat and the tip of the valve rod makes a stroke distance of the reciprocation longer;
• applying a voltage signal to the at least one piezoelectric actuator for its expansion and shrinkage along a second axis being identical to or different from the first axis, which causes pivotal movement of the lever, which in turn causes the reciprocation of the valve rod along the first axis between a top end and a bottom end of the reciprocation for dispensing of liquid through the nozzle, wherein the tip of the valve rod contacts the valve seat and applies an impact onto the valve seat when the valve rod is at the bottom end of the reciprocation;
• determining if the stroke distance has become longer;
• in response to determining that the stroke distance has become longer, making the top end of the reciprocation lower in the first axis and decreasing the stroke distance by changing the voltage signal applied to the at least one piezoelectric actuator to compensate the wearing out of the at least one of the valve seat and the tip of the valve rod.