| 摘要 |
PURPOSE:To eliminate the occurrence of the unevenness of rotation by making the 1st and 2nd differential couples formed of transistors operate by a singla constant- current source and by making the change in current be outputted by a current mirror circuit to excite a driving coil. CONSTITUTION:The 1st differential couple formed of transistors Q11 and Q12 wherein Hall elements H1 and H2 are connected with a base and the 2nd differential couple formed of Q21 and Q22 are provided and the constant current is supplied from transistors Q31 and Q32 biased with bias voltage Vb. Furthermore, the current mirror means Q13-Q18, Q23-Q28 which output the current proportional to the current flowing each current line of the differential couples are provided and the change in potential at the connecting points P1-P4 thereof is amplified by the 1st-4th emitter-follower couples to excite the driving coils L1 and L2. Since the supply of current is made from a single constant current source to differential couples, the occurrence of the unevenness of rotation due to the scattering of characteristics can be prevented. |
