PIEZOELECTRIC MOTEOR DRIVING METHOD AND AUTO FOCUSING METHOD USING THE SAME

摘要

A method for driving piezoelectric motor and an auto focusing method using the same are provided to maximize position accuracy without generation of an audible noise. A driving frequency supplied to a piezoelectric motor is set up as a predetermined starting frequency besides resonant frequency region(31). A square wave signal is supplied to the piezoelectric motor(35), and is a signal which is pulse width-modulated. A duty cycle rate of the square wave signal is different. A rotation speed of the piezoelectric motor is controlled according to a pulse width of the square wave signal. The driving frequency is controlled into a predetermined target frequency inside the resonant frequency region(32), and is compared with a target frequency(33). The piezoelectric motor is stopped when the driving frequency is higher than the target frequency(34). A step 32 is performed again when the driving frequency is lower than the target frequency.