Controlling an overshoot amplitude level based on a recording data pattern in a magnetic disk drive
View Patent ↗Embodiments of the present invention reduce lowering of a recording current and a recording magnetic field that might occur upon execution of write pre-compensation for compensating the NLTS according to a perpendicular magnetic recording method. According to one embodiment, the recording current overshoot is increased for recording a high NLTS recording data pattern. The read signal quality is improved, thereby a highly reliable magnetic disk can be provided.
1. A magnetic disk drive, comprising:
a recording head;
a perpendicular magnetic recording medium;
a recording current generation circuit for generating a recording current for recording information on said perpendicular magnetic recording medium with use of said recording head; and
a processor for analyzing a recording data pattern to obtain information of an overshoot amplitude level of said recording current and transferring said obtained information to said recording current generation circuit;
wherein said recording current generation circuit generates an overshoot added recording current according to said overshoot amplitude level information and adjusts an amplitude of the overshoot current according to a subject recording data pattern during recording to vary the recording current amplitude; and
wherein said overshoot amplitude level is set over a normal overshoot amplitude level for a recording data pattern in which at least N bits, where N: an integer of 3 or over, of non-transition parts are continued, then two magnetization transition parts appear consecutively.
2. The magnetic disk drive according to claim 1 ,
wherein said processor obtains said information of said overshoot amplitude level synchronously with a bit clock during a recording operation and transfers said level information to said recording current generation circuit.
3. The magnetic disk drive according to claim 1 ,
wherein said processor is included in a read/write (RW) channel.
4. The magnetic disk drive according to claim 1 ,
wherein said processor is included in a pre-amplifier together with said recording current generation circuit.
5. The magnetic disk drive according to claim 1 ,
wherein said processor has a reference table and inputs said recording data pattern and refers to its corresponding table to obtain said overshoot amplitude level information.
6. The magnetic disk drive according to claim 1 ,
wherein said processor has a state transition machine and enables said recording data pattern to be inputted to said state transition machine and obtains said level information from an output of said state transition machine.
7. A magnetic disk drive, comprising:
a recording head;
a perpendicular magnetic recording medium;
a recording current generation circuit for generating a recording current for recording information on said perpendicular magnetic recording medium with use of said recording head; and
a processor for analyzing a recording data pattern to obtain overshoot amplitude level information of said recording current and transferring said obtained level information to said recording current generation circuit,
wherein said recording current generation circuit generates an overshoot added recording current according to said overshoot amplitude level information and adjusts an amplitude of the overshoot current according to a subject recording data pattern during recording to vary the recording current amplitude; and
wherein said overshoot amplitude level information is set over a normal overshoot amplitude level for a recording data pattern in which at least N bits, where N: an integer of 3 or over, of non-transition parts are continued, then one magnetization transition part, one non-transition part, and one magnetization part appear respectively.
8. The magnetic disk drive according to claim 7 ,
wherein said processor obtains said overshoot amplitude level information synchronously with a bit clock during a recording operation and transfers said level information to said recording current generation circuit.
9. The magnetic disk drive according to claim 7 ,
wherein said processor is included in a read/write (RW) channel.
10. The magnetic disk drive according to claim 7 ,
wherein said processor is included in a pre-amplifier together with said recording current generation circuit.
11. The magnetic disk drive according to claim 7 ,
wherein said processor has a table and inputs said recording data pattern and refers to its corresponding table to obtain said level information.
12. The magnetic disk drive according to claim 7 ,
wherein said processor has a state transition machine and enables said recording data pattern to be inputted to said state transition machine and obtains said overshoot amplitude level information from an output of said state transition machine.