Apparatus including optical deflector controlled by saw-tooth voltage and its controlling method

An apparatus including an optical deflector and a control unit for controlling said optical deflector, wherein said optical deflector comprises:

• a mirror;
• a piezoelectric actuator adapted to rock said mirror around an axis of said mirror;
• and
• a piezoelectric sensor adapted to sense vibrations of said piezoelectric actuator,
• wherein said control unit comprises:
• a saw-tooth voltage generating block adapted to generate a saw-tooth voltage;
• an integral block adapted to calculate an integral voltage of a sum of a sense voltage of said piezoelectric sensor and a DC offset characteristic voltage;
• a DC offset characteristic voltage calculating block adapted to calculate said DC offset characteristic voltage in accordance with said integral voltage;
• a subtracter block, connected to said saw tooth voltage generating block and said integral block and adapted to generate a deviation between said saw-tooth voltage and said integral voltage;
• and
• a controller, connected to said subtracter block and adapted to generate a drive voltage in accordance with said deviation to apply said drive voltage to said piezoelectric actuator.