THERMAL SERVO SYSTEM FOR MECHANICAL POSITIONING
Original Publication Date: 1980-Oct-31
Included in the Prior Art Database: 2004-Apr-02
Xerox Disclosure Journal
Dimensional distortions of a magnetic disk 16 due to temperature fluctuations are compensated for by means of a thermal servo system which moves the plate supporting the head assembly drive 1 relative to a fixed supporting casting. A pretensioned wire 2, fastened at one end to a post 4 rigidly secured to an end of the head drive supporting plate 6 and at the other end to a post 8 mounted in a slot at the opposite end of the fixed supporting casting 10, is heated or allowed to cool, by a predetermined storage-controlled amount determined by the deviation from head/track alignment, to cause expansion or contraction of wire 2 and cor-responding slight movement of the head drive supporting plate 6 relative to the fixed supporting casting 10, thereby to correct for the deviation. A pretension is imparted to wire 2 by cantilever spring 12, and a portion of wire 2 is encircled by a toroidal winding 14 which acts as a primary of a transformer of which wire 2 is a one turn secondary whereby application of current to the toroidal winding 14 causes temperature modification of wire 2 and consequential slight changes in length of wire 2 with resulting slight movement of head drive supporting plate 6.