| 摘要 |
<p>PURPOSE:To simplify the adjustment of a switching point and to prevent a variation of the rotation of a drum due to a fluctuation of a head changeover signal by using an output of an A/D converter circuit at the time of resetting for a rotation control of the drum and using an output of the A/D converter circuit whenever it is outputted at the time of other purpose than the above for setting the time for generating the head changeover signal. CONSTITUTION:A changeover switch 30 is changed in order that a digital data of a changeover point setting voltage VA to be inputted from an A/D converter 22 to a CPU 27 is used by a head changeover signal generating timing calculation means 28 at the time of inputting a PG signal, and is used by a phase error calculating means 29 at the time of resetting. That is, the output of the A/D converter 22 is used for a rotation phase control of the drum, and other than this, the output of the A/D converter 22 for each time is used for setting the time for generating the head changeover signal. By this method, the switching point adjustment is simplified and rotational variations of the drum due to a fluctuation of the head changeover signal is prevented.</p> |
