| 摘要 |
PURPOSE:To shorten the time from a step pulse input to the transmission of a track zero position detection signal by utilizing also an exciting signal previous to a reference exciting signal from a pulse motor drive circuit at the time of shifting a magnetic head outside. CONSTITUTION:In accordance with a drive pulse STP and directional signal DIR, an exciting signal to each excitation phase is outputted from FFs 3, 6, 7, etc., to rotate to a step motor 1 by two excitation phase angles, and a magnetic head moves a disk by one recording track through a carrier. A phase A reference signal from an AND circuit 17 or 23 through an OR circuit 24 or a phase C exciting signal previous to the phase A reference signal at the time of shifting the head outside and an output from a track zero area detection circuit 19 are processed by an AND circuit 18 to generate a track zero position detection signal. With such constitution as to use also the exciting signal previous to the reference signal, the time from the step pulse input to the transmission of the track zero position detection signal can be shortened, and an erroneous action of an external control part can be prevented. |
