Patent ID: 7212372

Claim:
A magnetic tape, to be used at a running speed of at least 4,000 mm/sec., comprising a non-magnetic support, a magnetic layer formed on one surface of the non-magnetic support, and a backcoat layer formed on the other surface of the non-magnetic support, wherein servo signals for controlling tracking are recorded on the magnetic layer or the backcoat layer, and wherein the difference between the recording track width and the reproducing track width is 16 μm or less, wherein the value of [α/(Tw−Tr)] is 0.2 or less, wherein is α [in μm] is an amount of a weave occurring on one of both edges of the magnetic tape and on the side of reference for the running of the tape; Tw [in μm] is a recording track width; and Tr [in μm] is a reproducing track width, and wherein a coefficient of humidity expansion in the tape widthwise direction is (0 to 14)×10 −6 /% RH; and a coefficient of thermal expansion in the tape widthwise direction is (0 to 10)×10 −6 /° C.