| 摘要 |
PURPOSE:To improve the reliability of the brushless motor revolution detection by preparing a brightness control circuit to constantly fixing the incident rays of the light receiving element through a revolution discrimination track. CONSTITUTION:When the output of phototransistors 13, 15 is high-tention, the forward current flows respectively through the first stator coils 10a, 10b, the second stator coils 10c, 10d. And when the output of phototransistors 13, 15 is low-tention, the backward current flows respectively through the first stator coil 10a, 10b and the second stator coils 10c, 10d, so that the rotor magnet continues a fixed direction revolution. The brightness control circuit 101 compares the detection voltage of phototransistors 13, 15 with the reference voltage and controlls the current carrying capacity to the luminous diode 12 through the control transistor 38 or 39 to compensate the varying characteristic of luminous diode as well as the affection of disturbance. |
