Equivalent Circuit and Response of Moving-Coil Actuator

Abstract

In this paper, an equivalent circuit of a video tape recorder's moving-coil actuator for a dynamic track following system is indicated and its frequency response is investigated.
In order to obtain a fine tracking, it is necessary to suppress an actuator's mechanical resonance. It is known that daming depends on the driver's output impedance, so the actuator's frequency response was analyzed by using an equivalent circuit. As a result, the following relationship was obtained: Q_V=Q_A/P, where Q_V is the Q factor in voltage drive, Q_A the Q factor in current drive, and P the peak-to-minimum ratio of the input impedance.
Experimental results show this relationship and the same frequency response as analyzed one from DC to resonant frequency and above.