| 摘要 |
PURPOSE:To shorten a zero-position detection time by driving a motor so that a head is moved in a zero direction without reference to a signal which moves the head unless a track-zero-position detector detects a zero position in starting, and driving the motor after the detection according to a signal which moves the head in the zero direction and opposite direction. CONSTITUTION:A phototransistor (TR) 11b turns on unless the magnetic head 4 is at the track-zero position in starting, and an FF 25 is held in its initial state. An FF 29 is also held reset and its Q terminal is at a level L regardless of whether a direction signal DIR is (1) or (0). Namely, it outputs the signal which moves the head 4 to the zero position. Then, FFs 26 and 27 operate every time a step signal STP is inputted to output driving signals phiA, phiB, phiC, and phiD which move the head 4 to the zero position. The head 4 reaches the zero position and a shade plate 10 shades the TR 11b. A gate 24 outputs a zero signal TZS at the timing where the phiA and phiB are (1), and the FF 25 is set. Therefore, an FF 29 is set and reset by signals DIR of (1) and (0) and the driving signals vary so that the head 4 moves inward and outward. |
