Apparatus and method using a lock-in amplifier in the control of a periodic force applied to a moving part

摘要

An application for periodically applying a controllable force to a movable part has a force applying member, particularly for cutting a web, and a driver for driving the force applying member. The driver is controlled by a force-indicating signal produced by a lock-in amplifier to which a force-responsive signal and a reference signal are inputted. The lock-in amplifier operates to eliminate or reduce any noise present in the force-responsive signal.