Servo write head for writing servo patterns having opposite- polarity bars
The present disclosure generally relates to a servo write bar comprising one or more servo write heads for writing servo patterns on a tape. Each servo write head comprises a first end pole, a second end pole, and a center pole disposed between the first and second end poles. The center pole is spaced from the first end pole by a first gap, and spaced from the second end pole by a second gap. A coil coupled to a current source is disposed around the center pole. A top surface is disposed over the center pole, and the first and second end poles. A servo pattern is disposed on the top surface over the coil. A first servo line of the servo pattern is disposed over the first gap, and a second servo line of the servo pattern is disposed over the second gap.
1 . A servo write bar, comprising:
one or more servo write heads, each of the one or more servo write heads comprising:
a first end pole;
a second end pole;
a center pole disposed between the first and second end poles;
at least one coil wrapped around at least one of the center pole, the first end pole, or the second end pole;
a top pole disposed over the at least one coil, the first end pole, the second end pole, and the center pole, the top pole being disposed in contact with the first end pole, the second end pole, and the center pole, the top pole comprising a first channel and a second channel; and
a thin plate disposed over the top pole, the thin plate comprising a servo pattern, the servo pattern comprising a first servo line disposed between the first end pole and the center pole and a second servo line disposed between the center pole and the second end pole, wherein the first servo line is aligned with the first channel and the second servo line is aligned with the second channel, and wherein the first and second channels have a greater width than the first and second servo lines.
2 . The servo write bar of claim 1 , wherein the first and second servo lines are each disposed at an angle of about 12° to about 24° relative to a reference line that bisects the write head along the direction of the center pole to form a chevron pattern.
3 . The servo write bar of claim 1 , wherein the one or more servo write heads are five servo write heads.
4 . A device for writing servo patterns on a tape, comprising the servo write bar of claim 1 .
5 . The device of claim 4 , further comprising a current source coupled to the at least one coil.
6 . The device of claim 5 , wherein, during operation, the current source is configured to pulse current to the at least one coil to write the servo pattern on a tape.
7 . The servo write bar of claim 1 , wherein the first end pole is spaced from the center pole by a first gap, and the second end pole is spaced from the center pole by a second gap, the at least one coil being disposed in the first and second gaps.
8 . The servo write bar of claim 7 , wherein the first servo line is disposed over the first gap, and the second servo line is disposed over the second gap.
9 . The servo write bar of claim 1 , wherein the at least one coil is wrapped around the center pole.
10 . The servo write bar of claim 1 , wherein the at least one coil is a first coil and a second coil, wherein the first coil is wrapped around the center pole, and wherein the second coil is wrapped around the first end pole or the second end pole.
11 . A servo write bar, comprising:
one or more servo write heads, each of the one or more servo write heads comprising:
a first end pole;
a second end pole;
a center pole disposed between the first and second end poles, the center pole being spaced from the first end pole by a first gap and spaced from the second end pole by a second gap;
a coil disposed around the center pole and within the first and second gaps;
a top pole disposed in contact with the first end pole, the second end pole, and the center pole, the top pole comprising a first channel aligned with the first gap and a second channel aligned with the second gap, wherein the first gap has a greater width than the first channel and the second gap has a greater width than the second channel; and
a thin plate disposed over the top pole, the thin plate comprising a servo pattern disposed over the coil, the servo pattern comprising a first servo line disposed over the first channel and a second servo line disposed over the second channel, wherein the first channel has a greater width than the first servo line and the second channel has a greater width than the second servo line.
12 . The servo write bar of claim 11 , wherein the first and second servo lines are each disposed at an angle of about 12° to about 24° relative to a reference line that bisects the write head along the direction of the center pole to form a chevron pattern.
13 . A device for writing servo patterns on a tape, comprising the servo write bar of claim 11 .
14 . The device of claim 13 , further comprising a current source coupled to the coil.
15 . The device of claim 14 , wherein, during operation, the current source is configured to pulse current to the coil to write the servo pattern on a tape.
16 . The device of claim 15 , wherein the current pulse applies about 100 mAmps of current.
17 . The servo write bar of claim 11 , wherein the coil comprises ten or more turns.
18 . A servo write bar, comprising:
one or more servo write heads, each of the one or more servo write heads comprising:
a first end pole;
a second end pole;
a center pole disposed between the first and second end poles, the center pole being spaced from the first end pole by a first gap and spaced from the second end pole by a second gap;
a coil disposed around the center pole and within the first and second gaps;
a current source coupled to the coil;
a top pole disposed over the coil, the first end pole, the second end pole, and the center pole, the top pole comprising a first channel aligned with the first gap and a second channel aligned with the second gap, wherein the first gap has a greater width than the first channel and the second gap has a greater width than the second channel; and
a thin plate disposed over the top pole, the thin plate comprising a servo pattern, the servo pattern comprising a first servo line disposed over the first channel and a second servo line disposed over the second channel, wherein the first channel has a greater width than the first servo line and the second channel has a greater width than the second servo line.
19 . The servo write bar of claim 18 , wherein the first and second servo lines are each disposed at an angle of about 12° to about 24° relative to a reference line that bisects the write head along the direction of the center pole to form a chevron pattern.
20 . A device for writing servo patterns on a tape, comprising the servo write bar of claim 18 .
21 . The device of claim 20 , wherein each current pulse applies about 100 mAmps of current.
22 . The servo write bar of claim 18 , wherein the center pole, the top pole, and the first and second end poles each comprises one or more of an alloy of nickel and iron or an alloy of cobalt and iron.
23 . The servo write bar of claim 15 , wherein the first and second gaps each have a width of about 100 nm or greater.
24 . The device of claim 4 , wherein the device is configured to write a first servo line pattern and a second servo line pattern on a tape, wherein the first and second servo line patterns each individually have a positive magnetic field and a negative magnetic field.
25 . The device of claim 13 , wherein the device is configured to write a first servo line pattern and a second servo line pattern on a tape, wherein the first and second servo line patterns each individually have a positive magnetic field and a negative magnetic field.