JPS6481286A - Driving device of fine movement mechanism - Google Patents

Abstract

PURPOSE:To easily control a speed by a method wherein an electric current flowing to a piezoelectric element actuator used to drive a fine movement mechanism is controlled in order to prevent a vibration from being caused and in order to prevent acceleration from being increased. CONSTITUTION:When an amount of an electric charge to be accumulated in a piezoelectric element is designated as Q and the proportionality constant is designated as alpha, a displacement value (x) of the piezoelectric element due to an exerted electric field is expressed by Equation (1). When both sides of Equation (1) is differentiated with respected to time t, Equation (3) is obtained. The left side of Equation (3) represents a displacement speed of a piezoelectric element actuator 1, and since the differentiated term on the left side of Equation (3) represents an electric current flowing in the piezoelectric element actuator 1, it can be seen that the displacement speed of the piezoelectric element actuator 1 is proportional to the electric current flowing in the piezoelectric element actuator 1. Therefore, when the electric current flowing in the piezoelectric element actuator 1 is controlled by using an electric current control device 3, the displacement speed of the piezoelectric element actuator 1 can be controlled, and the operation speed at an output part of a fine movement mechanism 2 can be controlled easily without generating vibrations and without increasing acceleration.