Piezoelectric actuator

A piezoelectric actuator, comprising:

• a securing end, an actuation end, a piezoelectric assembly and a secondary driven member, wherein the piezoelectric assembly is configured to drive the secondary driven member to move at the securing end to enable the actuation end to move;
• a precompression magnet, wherein the precompression magnet is disposed on the secondary driven member and configured to interact with the securing end through magnetic forces to enable the secondary driven member to be pressed against the securing end with a preset pressure;
• and
• a decompression assembly comprising a decompression magnet and a decompression coil, wherein the decompression coil is configured to be electrified to have a magnetic field with magnetic properties identical or opposite to the magnetic properties of the decompression magnet to attract or repel the securing end, so as to keep the securing end stationary relative to the actuation end or to enable the securing end to move relative to the actuation end;
• or, the decompression coil is configured to allow a current in the decompression coil to change a direction to have a magnetic field with magnetic properties identical or opposite to magnetic properties of the decompression magnet.