| 摘要 |
<p>Stepper motor control circuitry is described including a phase locked loop circuit (120) formed by a phase detector (122) out putted to a filter (124) and a voltage controlled triangular and square wave generator (126) which has a frequency control input terminal (J) connected to the output of the filter (124) and which provides a square wave on an output (134) thereof connected as an input to the phase detector (122). An oscillator (144) drives the phase detector (122), and the outputs (132, 134, 140) of the generator (126) are connected as inputs to a pulse width modulated driver (146) which has its outputs connected to the coils (W, X, Y, Z) of the stepper motor. A differential amplifier (156) is connected across one of the coils (X) of the motor, and a balanced modulator synchronous detector or multiplier (168) has two inputs one of which constitutes an output of the differential amplifier and the other of which is a connection to the square wave output (134) of the generator (126). The output of the multiplier (168) constitutes an error signal which is supplied to a summing junction (176) between the filter (124) and generator (126) so that, upon the application of an instantaneous load to the stepper motor, the error signal causes a very quick return to normal speed of the motor.</p> |
