Optical sorter

An optical sorter comprising:

• a camera adapted to detect a to-be-sorted material at a detection position;
• a controller adapted to determine a to-be-sorted material to be removed, based on a detection result by the camera;
• and
• an air-jetting unit adapted to blow off and remove the to-be-sorted material to be removed using jet air of a compressed gas, based on a determination result by the controller, wherein
• the air-jetting unit includes:
• a piezoelectric valve adapted to perform valve opening and closing by driving a valve disc utilizing displacement of a piezoelectric element;
• and
• a valve driving unit adapted to apply a drive voltage to the piezoelectric element,
• the valve driving unit controls the drive voltage applied to the piezoelectric element in accordance with the to-be-sorted material to be removed by the controller to thus control a jet-air pressure of the compressed gas for removing the to-be-sorted material, and
• a value of the drive voltage applied to the piezoelectric element changes in accordance with the to-be-sorted material to be removed.