| 摘要 |
PURPOSE:To provide a pulse detector which can constantly and accurately obtain a rectangular waveform with a frequency which is proportional to a motor rotary speed. CONSTITUTION:An abnormal level detection means 26 and a count value switching circuit 28 are provided, it is constantly Judged whether an amplitude DC level of a reel FG pulse is at a level which is sufficient for waveform shaping or not, and then the offset voltage of an amplifier 20 is chanced slowly when the amplitude DC level is at a level which is sufficient for waveform shaping and rapidly when it is judged that the amplitude DC level is at a level which is sufficient for waveform shaping, thus achieving a configuration for reaching a target DC level rapidly. |
