| 摘要 |
1495459 Automatic control SIEMENS AG 12 March 1975 [29 March 1974] 10205/75 Heading G3N The speed of a magnetic tape is controlled by a time varying reference having a portion that is triggered by a tape start signal rizes linearly to a nominal tape speed, and a part that is triggered by a tape stop signal and falls at a greater rate. In the embodiment, tape drive motor MO is controlled according to the difference between an actual motor signal # from tachometer TA and the speed reference from device ST via potentiometer p which sets the nominal tape speed. The device ST, described with reference to Fig. 4 (not shown), is triggered by a binary start/stop signal S, to charge a capacitor at a given rate e.g. corresponding to the maximum permissible tape acceleration to give the rising speed reference, the capacitor being discharged at a faster rate by a switching transistor to provide the falling characteristic. The motor MO, and thus the tape, may be reversible. The above system minimises gaps between adjacent blocks of stored data on the tape. |
