Patent ID: 7212373

Claim:
A servo writer comprising: a tape running drive unit for running a magnetic tape in a longitudinal direction; a pulse signal generating circuit for generating pulse signals; a write head disposed on a running path of said magnetic tape, having a plurality of linear magnetic gaps thereon in a running direction of said magnetic tape at a predetermined interval, inputting pulse signals generated by said pulse signal generating circuit, and writing each of servo patterns one by one at the same timing corresponding to said magnetic gaps onto said magnetic tape with pitches between said servo patterns, wherein at least two of said plurality of linear magnetic gaps are parallel to each other; a read head disposed on a down-stream side of said write head on the running path of said magnetic tape, sensing each of said servo patterns written one by one at the same timing on said magnetic tape by the write head and outputting pulse signals corresponding to said sensed servo patterns; and a control unit for controlling said tape running drive unit based on a time interval between pulse signals, among the pulse signals output from said read head, resulted from two of appropriate linear patterns in parallel included in each of said servo pattern written at the same timing by the write head, so as to maintain constant the running speed of said magnetic tape.