Tension apparatus

Abstract

A tension apparatus includes a mechanical section, signal output section, smoothing circuit, maximum value holding circuit, constant current driving circuit, and discharge circuit. The mechanical section has an electromagnetic brake driven by an exciting current to generate an output torque and applies a tension to a material in continuous form which is being wounded and stretched by the output torque of the electromagnetic brake. The signal output section repeatedly outputs a PWM (Pulse Width Modulation) signal having a duty ratio corresponding to an input tension instruction value before and after a predetermined stop period. The smoothing circuit smoothes the PWM signal from the signal output section. The maximum value holding circuit holds a maximum voltage value of the smoothed PWM signal. The constant current driving circuit supplies an exciting current corresponding to the held maximum voltage value to the electromagnetic brake. The discharge circuit resets holding operation of the maximum value holding circuit on the basis of a magnitude comparison result between a current tension instruction value and a previous tension instruction value.

Dependencies are inferred from the claim text.