| 摘要 |
PURPOSE:To detect both FG signal and index signal by producing a signal having amplitude larger by an extent corresponding to one period of a signal produced from a frequency generator in an index mechanism for a spindle motor. CONSTITUTION:An SG signal 1 comprises an FG signal 1-a and an index signal 1-b having amplitude magnified by an extent corresponding to one period of the FG signal 1-a and period of 1 pulse/revolution. The SG signal 1 is amplified through an amplifier circuit 2 and the frequency signal of the FG is taken out through a zero-cross detecting circuit 3. On the other hand, the SG signal 1 is amplified and the peak of the index signal 1-b is detected through a peak detecting circuit 4 thus taking out a signal of 1 pulse/revolution. According to the constitution, both the FG signal and the index signal can be detected from one signal and the index signal can be taken out without requiring the parts at the index section. |
