A position control device has a piezoelectric actuator, a power supply for
applying voltage to the piezoelectric actuator, a position control unit,
and a reverse low voltage control unit. The position control unit
identifies a position control state in which position control is
performed by displacing the piezoelectric actuator and a standby state
that does not require the position control, and controls the position.
When the position control unit identifies the standby state, the reverse
low voltage control unit sets a reverse low voltage that is directed
opposite to the polarization direction of the piezoelectric film and is
lower than a coercive voltage and a set time during which the reverse low
voltage is applied, and transmits a power supply control signal for
generating the set reverse low voltage and set time to the power supply.
Thus, a large displacement amount is achieved and a long lifetime can be
realized.