| 摘要 |
<p>PURPOSE:To facilitate the tape speed control at the time of high-speed running by extracting a clock from a digital signal recorded in a tape, detecting the frequency of the clock, and controlling the tape speed based on the frequency information. CONSTITUTION:A current reproduced by heads 105a, 105b is supplied to a PLL 107 via a head amplifier 106; a reproduced clock corresponding to the shortest wavelength is extracted and supplied to a PLL frequency detection part 108. The PLL frequency detection part detects a PLL frequency by using the reproduced clock (b) and the reproduced signal (a) from the head amplifier 106, and supplies the result to a tape speed control part 110. The tape speed control part 110, by using a speed data (e) set by a tape speed setting part 109, provides the parameter of the number of revolution of a cylinder to a cylinder servo 111 so that the PLL frequency fp comes equal or close to the value during the normal reproduction when the targeted speed of tape is reached. In such a way, the tape speed is controlled.</p> |
