| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to sine-wave-drive two stepping motors via two PWM circuits using one CPU, by energizing each phase of the two-phase stepping motors according to the output of a triangular-wave generate circuit and the output of an invert circuit that inverts the output of the triangular-wave generate circuit. SOLUTION: The waveform of phase A is obtained by smoothing the output of a PWM circuit 1a of CPU 1 using a resistor 5 and a capacitor 6, an exhibits the form of triangular waves. The waveform of phase B is that obtained by inverting the waveform of phase A, and converted into a sine wave by polygonal line approximation. Polygonal line approximation circuits 7, 9 are formed by connecting in parallel a plurality of rows of diodes to each of which bias voltage is applied and adding the diodes to the anodes of diodes through input terminals and impedance elements. The bias voltage applied to each diode is varied one by one, and sine-wave signals are thereby obtained from triangular waves. The waveform converted into sine wave is input to the reference voltage Vref terminals of drive circuits 2, 10, and thus currents in the waveform of phases A and B are passed through coils in phases A and B. |
