Patent ID: 7212365

Claim:
A servo writer for writing a servo signal on a tape, the servo writer including a supply reel for feeding the tape, and a take-up reel for winding the tape, the servo writer comprising: a write head for writing the servo signal on the tape; a verifying head for reading the servo signal written by the write head in order to inspect the servo signal, the verifying head being positioned downstream of the write head in a transport direction of the tape; an inspection section for checking whether or not the servo signal being read by the verifying head contains an abnormality; an overwrite head for overwriting, with a new servo signal, a portion where the abnormality is detected by the inspection section, the overwrite head being disposed adjacent to the verifying head in a downstream direction of the transport direction of the tape; and an overwrite controller for determining timing of overwriting the servo signal, based on the transport speed of the tape and a distance between the verifying head and the overwrite head, wherein the overwrite head overwrites the servo signal under control of the overwrite controller, and wherein the overwrite controller comprises a phase compensation circuit which monitors the phase of the servo signal written on the magnetic tape upon receiving a new pattern block from the servo signal inspection section, confirms that the phase of the written servo signal reaches a predetermined phase and delivers a control signal to the servo signal output section so as to send a new pattern block to the overwrite head.