SERVO SYSTEM

摘要

SERVO SYSTEM A master tape movable in a closed loop including a pinch roller transfers a mirror image to a slave tape movable in a closed loop including a capstan. A thermomagnetic layer on the slave tape has a Curie temperature above which magnetic information is destroyed and below which magnetic information can be recorded on such layer. The thermomagnetic layer is heated above the Curie temperature and is accordingly lengthened by thermal expansion just before the slave tape reaches the capstan. A first guide contiguous to the heater regulates the slave tape tension. A downstream portion of a peripheral surface, preferably defining a cylindrical segment, on the guide receives a pressurized fluid for sensing the tape tension in accordance with the tape width, distance from the cylinder axis, and the fluid pressure. An upstream portion of the peripheral surface receives a vacuum adjustable to vary the spacing between the slave tape and the downstream portion. This regulates the tape tension. The master tape is lengthened by a second guide having the same construction as the first guide to compensate for the lengthening of the slave tape by the heater and the first guide, thereby producing a true mirror image on the slave tape after the slave tape has cooled to the ambient temperature. Each of the master tape and the slave tape has a particular product of the Youngs modulus, tape width and tape thickness to provide a controlled strain on the tape when the tension on the tape is regulated.