| 摘要 |
<p>PURPOSE:To prevent a malfunction, and to execute stable tracking control by providing a generating means of a specified signal, and providing a means for detaching an ATF control loop from a main servo-loop by the signal, in case the first or the second timing signal is not generated for a prescribed period. CONSTITUTION:At the time of an S/H2 timing signal 14 has been outputted as shown by 25, namely, in case an S/H2 timing has not been generated continuously for about one second, an ATF-NG signal is outputted. This signal switches a switch 18 and detaches an ATF control system (a phase system of a capstan). That is to say, to a control signal output terminal 19, a prescribed voltage 1/2 Vcc being about the center value of a phase voltage is outputted. This output is supplied to a motor together with a speed error signal, and a servo- loop becomes only a speed system. In this way, by operating a counter of 6 bits by utilizing the S/H2 timing signal, the malfunction can be prevented comparatively easily.</p> |
