A servo writer is provided, which applies DC magnetization to a zone of a magnetic tape that is in advance subjected to AC erasing and writes a servo signal onto the DC magnetized zone. The servo writer has a DC erasing head and a servo signal writing head. The DC erasing head conducts DC erasing by applying DC magnetization to the magnetic tape which travels past the DC erasing head. The servo signal writing head writes the servo signal onto the magnetic tape downstream relative to the DC erasing head in a direction of traveling of the magnetic tape. In this servo writer, one of the DC erasing head and the servo signal writing head has an integrally formed flange which is able to restrict widthwise misalignment of the magnetic tape.
1. A servo writer which applies AC erasing to a zone of a magnetic tape that is in advance subjected to DC magnetization and writes a servo signal onto the DC magnetized zone, comprising:
an AC erasing head for conducting AC erasing of a part of the DC magnetized tape by applying AC magnetization to the magnetic tape which travels past the AC erasing head; and
a servo signal writing head for writing the servo signal onto the remaining DC magnetized zone of the magnetic tape downstream relative to the AC erasing head in a direction of traveling of the magnetic tape,
wherein one of the AC erasing head and the servo signal writing head has an integrally formed flange which is able to restrict widthwise misalignment of the magnetic tape.
2. A servo writer according to claim 1 , wherein each of the AC erasing head and the servo signal writing head has the flange.
3. A servo writer according to claim 2 , wherein a surface of each of the AC erasing head and the servo signal writing head which the magnetic tape travels past is flat, and the flange is adapted to be of a shape of plate which thoroughly runs on both sides of the surface in the direction of traveling of the magnetic tape.
4. A servo writer according to claim 2 , wherein a surface of each of the AC erasing head and the servo signal writing head which the magnetic tape travels past is flat, and the flange is adapted to be of a shape of plate which thoroughly runs on one side of the surface in the direction of traveling of the tape, wherein a flange for the AC erasing head and the other flange for the servo signal writing head are adapted to be opposite with each other.
5. A servo writer according to claim 1 , wherein a surface of the AC erasing head which the magnetic tape travels past is flat, and the flange is adapted to be of a shape of plate which thoroughly runs on both sides of the surface in the direction of traveling of the magnetic tape.
6. A servo writer according to claim 5 , wherein the surface of the erasing head is substantially parallel to the direction of traveling of the magnetic tape.
7. A servo writer according to claim 1 , wherein a surface of the servo signal writing head which the magnetic tape travels past is flat, and the flange is adapted to be of a shape of plate which thoroughly runs on both sides of the surface in the direction of traveling of the magnetic tape.
8. A servo writer according to claim 1 , wherein a height of the flange is adapted to be 1 to 4 times as large as a thickness of the magnetic tape.
9. A servo writer according to claim 1 , wherein the servo signal writing head records the servo signal by oppositely magnetizing the DC magnetized zone.