Recording method, unload method, and magnetic disk
View Patent ↗Embodiments of the present invention prevent occurrence of a write pole erasure in the event of a power failure within a magnetic disk apparatus of a perpendicular magnetic recording system. According to one embodiment of the present invention, a recording current is flowed through a magnetic head to record data in a magnetic disk. An occurrence of a power failure in the magnetic disk apparatus is detected. When a power failure has occurred, the recording head is demagnetized with power in case of a power failure. The recording head is unloaded after the recording head has been demagnetized. For the power in case of a power failure, back electromotive force of a spindle motor can be utilized. As a result, effects exerted on data recorded in the magnetic disk due to residual magnetism remaining in the recording head can be eliminated.
1. A method, in a magnetic disk apparatus of a perpendicular magnetic recording system, for recording data comprising the steps of:
recording data in a magnetic disk by flowing a recording current through a recording head;
flowing a recording current to degauss through said recording head when supply voltage to said magnetic disk apparatus drops during said recording step; and
moving said recording head subsequent to said step of flowing said recording current to degauss.
2. The method for recording according to claim 1 , wherein
said step of flowing a recording current to degauss includes a step of generating a recording current to degauss from a back electromotive force of a spindle motor.
3. The method for recording according to claim 1 , wherein
said step of flowing a recording current to degauss includes a step of generating a recording current to degauss from electrical energy stored in a capacitor.
4. The method for recording according to claim 1 , wherein
said step of moving said recording head includes a step of unloading a carriage with head gimbals assembly (HGA).
5. The method for recording according to claim 1 , wherein
said recording current to degauss is an AC current having a monotonously decreasing function as its envelope.
6. The method for recording according to claim 1 , wherein
said recording current to degauss is a DC current.
7. A method for unloading a carriage with HGA in a magnetic disk apparatus of a perpendicular magnetic recording system comprising the steps of:
loading a head/slider over a magnetic disk;
identifying an operating mode when supply voltage to said magnetic disk apparatus drops while said head/slider is being loaded;
flowing a recording current to degauss through a recording head when a recording mode is identified in said identifying step; and
unloading said carriage with HGA subsequent to said recording current to degauss flowing step.
8. The method for unloading according to claim 7 , further comprising a step of unloading said head/slider without flowing a recording current to degauss through said recording head when a reproduction mode is identified in said identifying step.
9. The method for unloading according to claim 7 , wherein
said step of unloading includes a step of supplying a voice coil of said carriage with HGA with power generated from a back electromotive force of a spindle motor.
10. The method for unloading according to claim 7 , wherein
said step of flowing a recording current to degauss includes a step of generating a recording current to degauss from a back electromotive force of a spindle motor or energy stored in a capacitor.
11. A magnetic disk apparatus of a perpendicular magnetic recording system comprising:
a magnetic disk;
a spindle motor for rotating said magnetic disk;
a recording head for recording data in said magnetic disk;
a carriage with HGA for positioning said recording head in a predetermined position over said magnetic disk;
a recording current generating portion for supplying a recording current to said recording head;
a voltage drop detecting portion for detecting a drop in power voltage supplied to said magnetic disk apparatus; and
a demagnetizing portion for supplying said recording head with a recording current to degauss in response to an output from said voltage drop detecting portion.
12. A magnetic disk apparatus according to claim 11 , wherein
said demagnetizing portion includes a switch circuit for having power, which is supplied to a recording current to degauss generating circuit generating an AC recording current to degauss and said recording current to degauss generating circuit, switched between normal power and power in case of a power failure.
13. The magnetic disk apparatus according to claim 12 , wherein
said power in case of a power failure is generated from a back electromotive force of said spindle motor.
14. The magnetic disk apparatus according to claim 12 , wherein
said switch circuit includes an operating mode identifying portion for identifying an operating mode of said magnetic disk apparatus and said operating mode identifying portion allows, only when identifying that said magnetic disk apparatus is operating in a recording mode, said recording current to degauss generating circuit to output a recording current to degauss in response to an output from said voltage drop detecting portion.
15. The magnetic disk apparatus according to claim 12 , wherein
said recording current to degauss generating circuit is accommodated in a head amplifier attached to said carriage with HGA.
16. The magnetic disk apparatus according to claim 11 , wherein
said switch circuit supplies a retracting current generated from a back electromotive force of said spindle motor to a voice coil of said carriage with HGA after said recording current to degauss has been supplied for a demagnetizing time, to thereby unload said carriage with HGA.
17. The magnetic disk apparatus according to claim 11 , wherein
said magnetic disk apparatus employs a load/unload system by use of a ramp mechanism.
18. The magnetic disk apparatus according to claim 11 , wherein
said magnetic disk apparatus employs a contact start/stop system by having a retract region provided on said magnetic disk.
19. The magnetic disk apparatus according to claim 11 , wherein
said recording head is a monopole type recording head.
20. The magnetic disk apparatus according to claim 11 , wherein
said demagnetizing time is a predetermined time period within a range of 50 nanoseconds to 100 nanoseconds.