High-density recording method for hard disk drives and a pre-amplifier circuit suitable for use with same
View Patent ↗A magnetic recording method is provided where ternary data is recorded on a magnetic recording medium by forming a first area that corresponds to a first value of the data and in which a first magnetization state is continued at least during the minimum write width. A second area that corresponds to a second value of the data in which a second magnetization state is oppositely magnetized as compared with the first magnetization state is continued at least during the minimum write width. A third area that corresponds to a third value of the data in which the magnetic intensity detected by the read head corresponds to a “0.” Accordingly, the ternary data can be recorded using the characteristic that a signal having a width narrower than the detection width of the read head is not detected by the read head.
1. A perpendicular magnetic recording-method for recording data on magnetic recording medium, wherein the data has a minimum write width corresponding to at least a read detection width of a read head, the method comprising:
perpendicularly recording ternary data in a first area on the magnetic recording medium corresponding to a first data value, the data recorded in the first area having a first magnetization state which continues at least during the minimum write width;
perpendicularly recording ternary data in a second area on the magnetic recording medium corresponding to a second data value, the data recorded in the second area having a second magnetization state which continues at least during the minimum write width, the second magnetization state being oppositely magnetized from the first magnetization state; and
perpendicularly recording ternary data in a third area on the magnetic recording medium corresponding to a third data value by alternating the first magnetization state and second magnetization state, each having a write width narrower than the minimum write width.
2. The method of claim 1 , wherein third area is formed by alternating the first magnetization state and the second magnetization state, each having a write width narrower than ½ the minimum write width.
3. The method of claim 1 , wherein the third area is formed by alternating the first magnetization state and the second magnetization state, each having a write width narrower than ¼ the minimum write width.
4. The method of claim 1 , wherein the intensity of a mean magnetic flux detected by the read head in the third area is 0.
5. A perpendicular magnetic recording-method for recording ternary data on magnetic recording medium, wherein the data is recorded according to a minimum write width corresponding to a read detection width defined in relation to a read head, the method comprising:
perpendicularly recording ternary data in a first area on the recording medium magnetized according to a first magnetization state, such that the intensity of magnetic flux detected by a read head from the magnetic recording medium corresponds to a data value of;
perpendicularly recording ternary data in a second area on the recording medium magnetized according to a second magnetization state, such that the intensity of magnetic flux detected by the read head from the magnetic recording medium corresponds to a data value of 1; and
perpendicularly recording ternary data in a third area on the recording medium magnetized according to the first and second magnetization states, such that the intensity of magnetic flux detected by the read head from the magnetic recording medium corresponds to a data value of 0, and each one of the first and second magnetization states magnetizing the recording medium in the third area is recorded with a width narrower than the minimum write width.
6. A pre-amplifier circuit applying a write current to a write head during a perpendicular magnetic recording method to record data having a minimum write width corresponding to a detection width of a read head, the pre-amplifier circuit comprising:
a direct current (DC) signal generator generating a DC signal having a predetermined amplitude;
a first switch circuit applying the DC signal from the DC generator to the write head in a first direction during a period in which the data to be recorded has a first value;
a second switch circuit applying the DC signal from DC generator to the write head in a second direction opposite to the first direction during a period in which the data to be recorded has a second value;
a high frequency signal generator generating a high frequency signal having a higher frequency than a write frequency corresponding to the minimum write width; and
a third switch circuit applying the high frequency signal to the write head during a period in which the data to be recorded has a third value.
7. The pre-amplifier circuit of claim 6 , wherein the first, second and third switch circuits operate according to the value of the data.
8. A magnetic recording apparatus comprising:
a write head generating a magnetic field for perpendicularly magnetizing a magnetic recording medium with respect to an upper surface of the recording medium; and
a pre-amplifier circuit having a direct current (DC) signal generator which generates a DC signal having a predetermined amplitude, and an alternative current (AC) signal generator, which generates a high frequency signal having a higher frequency than a write frequency corresponding to a write width of a read head, and supplying a write current corresponding to data to be recorded by the write head, wherein the pre-amplifier circuit applies the DC signal to the write head in a first direction during a period in which the data to be recorded on the magnetic recording medium has a first value, the pre-amplifier circuit applying the DC signal to the write head in a second direction during a period in which the data to be recorded has a second value, and the pre-amplifier circuit applying the high frequency signal to the write head during a period in which the data to be recorded has a third value.