| 摘要 |
PURPOSE:To provide a motor drive device used to drive a turntable or the like by incorporating a control circuit for controlling the balance voltage of a hall voltage in a hall element as a rotor position detector by the balance voltage of a hall voltage of other hall element. CONSTITUTION:Control transistors (TR) Q7, Q8 are selectively conducted as a result of comparing the output voltages HB1, HB2 at both terminals of a hall effect element H2 as a rotor position detector with the voltage of a bias power supply EB. Switching transistors Q3, Q4 are alternatively conducted by the relationship between the collector potentials of the control transistors Q7, Q8 and a voltage ES across a constant current drive circuit SD to thus supply a constant current IS alternatively to stator windings W3, W4. The balanced voltage between the hall voltages from the hall voltage output terminals of the elements H1, H2 are extracted via resistors R1-R4 of the same resistance, and one of the bias current of the elements H1, H2 is controlled via an operational amplifier A1 by the other thereof as a standard to thereby control so that the balance voltage may become the same as that at the standard side. |
