Composite magnetic head and process for producing the same

1. A composite magnetic head comprising:

a DC-erasing head, which is slidably contact with a driving magnetic tape, and which DC-erases a servo band of said magnetic tape in such a manner that the direction of the magnetization of said servo band the servo band is directed towards one direction of the lengthwise direction of said magnetic tape;

a servo writing head, which is slidably contact with said magnetic tape, and which writes a servo signal thereon so that the direction of the magnetization of the servo band is directed toward the reverse direction to the direction directed by the DC erasing head; and

an AC-erasing head, which is contact with said magnetic tape, and which AC-erases the magnetization of the data band of said magnetic tape;

said servo writing head and said AC-erasing head being provided at downstream of the driving magnetic tape relative to the DC-erasing head, and

said DC-erasing head, said servo writing head and said AC-erasing head being unified with each other.

2. The composite magnetic head according to claim 1 , wherein said DC-erasing gap of the DC-erasing head and the servo writing gap of the servo writing head are formed by simultaneous patterning by a photolithographic method utilizing a single mask.

3. The composite magnetic head according to claim 2 , wherein said DC-erasing head, said servo writing head, and said AC-erasing head are conjugated via a non-magnetic member.

4. The composite magnetic head according to claim 2 , wherein the core making up the DC-erasing head, the core making up the servo writing head, and/or the core making up the AC-erasing head are made of a soft magnetic material.

5. The composite magnetic head according to claim 4 , wherein said soft magnetic comprises an Ni—Fe alloy, sendust, alperm, or an amorphous alloy.

6. The composite magnetic head according to claim 2 , wherein said servo writing gap comprises a two non-parallel non-linear pattern.

7. The composite magnetic head according to claim 2 , wherein said C-erasing gap of the AC-erasing head comprises a liner pattern connecting one end of the AC-erasing head in the width direction to the other end thereof.

8. The composite magnetic head according to claim 1 , wherein said DC-erasing head, said servo writing head, and said AC-erasing head are conjugated via a non-magnetic member.

9. The composite magnetic head according to claim 8 , wherein said non-magnetic member comprises aluminum titanium carbide, a non-magnetic ferrite, calcium titanate, or silica.

10. The composite magnetic head according to claim 8 , wherein said non-magnetic member comprises aluminum titanium carbide, a non-magnetic ferrite, calcium titanate, or silica.

11. The composite magnetic head according to claim 1 , wherein the core making up the DC-erasing head, the core making up the servo writing head, and/or the core making up the AC-erasing head are made of a soft magnetic material.

12. The composite magnetic head according to claim 11 , wherein said soft magnetic comprises an Ni—Fe alloy, sendust, alperm, or an amorphous alloy.

13. The composite magnetic head according to claim 1 , wherein said servo writing gap comprises a two non-parallel non-linear pattern.

14. The composite magnetic head according to claim 1 , wherein said AC-erasing gap of the AC-erasing head comprises a liner pattern connecting one end of the AC-erasing head in the width direction to the other end thereof.

15. A process for producing a composite magnetic head, the process comprising:

forming a core making-up a DC-erasing head;

forming a core making up a servo writing head;

forming a core making up an AC-erasing head, and forming thereon an AC-head gap, which AC-erases the magnetization of a magnetic tape;

unifying the core of the DC-erasing head, the core of the servo writing head, and the core of the AC-erasing head with each other;

forming a DC-erasing gap, which DC-erases magnetization of a magnetic tape, on the core of the DC-erasing head; and

forming a servo writing gap, which writes a servo signal on a magnetic tape, on the core of the servo writing head;

said DC-erasing gap and said servo writing gap being formed by a simultaneous patterning according to a photolithographic method utilizing a single mask.

16. A tape drive comprising:

a composite magnetic head comprising:

a DC-erasing head, which is slidably contact with a driving magnetic tape, and which DC-erases a servo band of said magnetic tape in such a manner that the direction of the magnetization of said servo band the servo band is directed towards one direction of the lengthwise direction of said magnetic tape;

a servo writing head, which is slidably contact with said magnetic tape, and which writes a servo signal thereon so that the direction of the magnetization of the servo band is directed toward the reverse direction to the direction directed by the DC erasing head; and

an AC-erasing head, which is contact with said magnetic tape, and which AC-erases the magnetization of the data band of said magnetic tape;

said servo writing head and said AC-erasing head being provided at downstream of the driving magnetic tape relative to the DC-erasing head, and

said DC-erasing head, said servo writing head and said AC-erasing head being unified with each other,; and

a tape driving system.

17. The tape drive according to claim 16 , wherein said DC-erasing gap of the DC-erasing head and the servo writing gap of the servo writing head are formed by simultaneous patterning by a photolithographic method utilizing a single mask.

18. The tape drive according to claim 16 , wherein said servo writing head, and said AC-erasing head are conjugated via a non-magnetic member.

19. The tape drive according to claim 16 , wherein said DC-erasing head, said servo writing head, and said AC-erasing head are conjugated via a non-magnetic member.

20. The tape drive according to claim 16 , wherein said servo writing gap comprises a two non-parallel non-linear pattern.