| 摘要 |
<p>1463166 Automatic control systems SONY CORP 8 Feb 1974 [9 Feb 1973] 05899/74 Heading G3R [Also in Division G5] In a method of copying recordings from a master magnetic tape 3 on to a slave magnetic tape 6 by bringing the two tapes into contact while the slave tape is at an elevated temperature, tension is applied to the master tape so that is is in stretched condition when contacted with the slave tape to compensate for shrinkage of the slave tape on cooling to ambient temperature. A slave tape tension sensing arm 67 controls a capstan motor 17 to maintain tension in the slave tape 6 constant between capstan 15 and pinch roller 16 and pointing roller 7, 8, tape 6 being heated along this stretch by heaters 71, 72 to the vicinity of, or higher than, the curie temperature of tape 6. Roller 7 is driven by a hysteresis synchronous motor 9 powered by amplifier 23, 24, 25 fed by an oscillator 21 via a frequency dividing circuit 50 and a ring counter 22. A tension sensing arm 62 sensor master tape tension in the run between capstan 10 and rollers 7, 8 and adjusts the output of a control signal circuit 64 so that the hysteresis synchronous motor 12 of capstan 10 is driven at a speed to maintain the required amount of stretching of the master tape 3, the control signal being compared with a reference signal in comparator 32 giving a signal controlling a phase or frequency shift circuit 26 having an input connected to oscillator 21 and an output connected to ring counter 27. Motor 12 may alternatively be controlled to maintain the required amount of master tape stretch by means of (a) a control signal recorded on the master tape 6 and sensed by a head (33), Fig. 2 (not shown), between rollers 11 and 8, the output of head (33) being compared with a reference signal, or b sensing a control signal on tape 3 by a head (35), Fig. 3 (not shown), upstream of roller 11 and comparing the output of head (35) with that of a head (36) located to sense the control signal copied on to tape 6 and positioned downstream of roller 7, 8, tape 6 having shrunk by the time it contacts head (36), or c recording a control signal on to tape 3 by a head (39), Fig. 4 (not shown), upstream of roller 11 and comparing the signal fed to head (39) with the output of a head (40) located downstream of rollers 7, 8 to detect the control signal copied on to tape 6, or d recording a control signal on to two tracks of tape 3 by heads (43), (44), Fig. 5 (not shown), located upstream of roller 11 and spaced apart lengthwise of the tape 3 by a distance (l), and comparing with one another the outputs of heads (45), (46) located downstream of rollers 7, 8 and spaced lengthwise of tape 6 by the distance (l) to play back the two control tracks copied on to tape 6.</p> |
