| 摘要 |
<p>PURPOSE:To drive accurately and assuredly a capstan when a tape is driven at a low speed and to reduce the noise produced by a revolving gear in a high- speed drive mode of the tape, by providing the 1st and 2nd control members which control the revolutions of the 1st and 2nd rotors and the 1st and 2nd outer gears. CONSTITUTION:In a low-speed driving mode of a tape, the signals are sent to a servo motor 11 and an output shaft 12 is revolved clockwise. The revolutions of the shaft 12 are transmitted to a capstan 1 from the 2nd sun gear 31 via each gear. A pinch roller 5 is pressed to the capstan 1 by a spring, and a magnetic tape held between the roller 5 and the capstan 1 is driven at a fixed speed with revolutions of the capstan 1. While in a high-speed driving mode of the tape, the rotational frequency of the 1st sun gear is set at N21. At the same time, the 1st planetary gear 22 revolves round the gear 21 with a rotationary frequency N25. Therefore the engagement rotational frequency between gears 21 and 22 is equal to (N21-N25) with the reduction equivalent to the share of N25. Thus the noise produced by the engagement are reduced by a degree equivalent to the engagement rotational frequency equal to N25 compared with the rotational frequency N15=Nout=N21 of a capstan gear 15.</p> |
