IPC분류정보
국가/구분 |
United States(US) Patent
등록
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국제특허분류(IPC7판) |
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출원번호 |
US-0062835
(2002-01-31)
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발명자
/ 주소 |
- Codilian, Raffi
- Gibbons, Kent W.
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출원인 / 주소 |
- Western Digital Technologies, Inc.
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대리인 / 주소 |
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인용정보 |
피인용 횟수 :
59 인용 특허 :
3 |
초록
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A hard disk drive that determines a saturation current of a voice coil motor (VCM) during the acceleration portion of a seek operation, and uses the information to advantageously adjust current profile for subsequent portion of the seek. One example of determining the saturation current is utilizati
A hard disk drive that determines a saturation current of a voice coil motor (VCM) during the acceleration portion of a seek operation, and uses the information to advantageously adjust current profile for subsequent portion of the seek. One example of determining the saturation current is utilization of the peak value of the saturated acceleration current whose magnitude depends on operating conditions such as temperature and supply voltage. Traditional hard disk drives use predetermined seek current profiles that are formed conservatively to account for such variations in the available current to the VCM, at the expense of sacrificing some seek performance. By determining the available current for each seek operation, the current profile can be adjusted on the fly so as to improve the seek performance.
대표청구항
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1. A hard disk drive comprising:a rotatable disk having a magnetic recording media wherein the rotatable disk defines a plurality of concentric servo tracks;a pivotable actuator that is movable with respect to the rotatable disk;a transducer disposed on the actuator so as to be movable with respect
1. A hard disk drive comprising:a rotatable disk having a magnetic recording media wherein the rotatable disk defines a plurality of concentric servo tracks;a pivotable actuator that is movable with respect to the rotatable disk;a transducer disposed on the actuator so as to be movable with respect to the disk so as to be positionable on a selected servo track of the plurality of concentric servo tracks;a voice coil motor that moves the pivotable actuator in response to an applied current so as to permit movement of the transducer from a first location to a second location wherein movement comprises an acceleration phase and a deceleration phase; anda controller for controlling the applied current according to a current profile, wherein the current profile has a first portion corresponding to the acceleration phase, and a second portion corresponding to the deceleration phase, and wherein the controller monitors a parameter indicative of the movement of the actuator during the application of the first portion of the current profile to determine a performance related parameter and wherein the controller then utilizes the performance related parameter to adjust the configuration of the second portion of the current profile to thereby reduce the time needed to position the transducer adjacent the second servo track. 2. The hard disk drive of claim 1, wherein the performance related parameter is peak acceleration current magnitude. 3. The hard disk drive of claim 2, wherein the peak acceleration current is a saturation current whose magnitude depends on operating condition of the disk drive. 4. The hard disk drive of claim 3, wherein the saturation current at a given operating condition defines a full range of current available for application to the voice coil motor. 5. The hard disk drive of claim 4, wherein determination of the saturation current magnitude permits adjustment of the current profile to utilize more of the full range of the available current. 6. The hard disk drive of claim 1, wherein the performance related parameter is an average acceleration current magnitude. 7. The hard disk drive of claim 6, wherein the average accelerating current magnitude corresponds to an average saturated accelerating current. 8. The hard disk drive of claim 1, wherein the parameter indicative of the movement of the actuator is the current being applied to the voice coil motor. 9. The hard disk drive of claim 8, wherein the current is measured directly by an analog to digital converter. 10. The hard disk drive of claim 1, wherein the parameter indicative of the movement of the actuator is displacement of the transducer. 11. The hard disk drive of claim 10, wherein the displacement of the transducer is determined by monitoring the servo wedges and track IDs encountered by the transducer. 12. The hard disk drive of claim 11, wherein rate of change of displacement of the transducer permits monitoring of velocity of the transducer. 13. The hard disk drive of claim 12, wherein rate of change of velocity of the transducer permits monitoring of acceleration of the transducer. 14. The hard disk drive of claim 13, wherein the rate of change of velocity is determined by monitoring back-emf induced in the voice coil motor. 15. The hard disk drive of claim 14, wherein the current being applied to the voice coil motor is inferred from the acceleration of the transducer. 16. The hard disk drive of claim 15, wherein the acceleration of the transducer is linearly proportional to the current being applied to the voice coil motor. 17. The hard disk drive of claim 1, wherein the parameter indicative of the movement of the actuator is displacement of the transducer during a predetermined time interval. 18. The hard disk drive of claim 17, wherein the displacement of the transducer is correlated to a saturation point of a demanded digital to analog converter (DAC) value. 19. The hard disk drive of claim 18, wherein the correlation between the displacement and the saturation DAC value is obtained from a lookup table. 20. The hard disk drive of claim 19, wherein the lookup table is determined during calibration of the disk drive. 21. The hard disk drive of claim 1, wherein the movement of the transducer comprises a seek operation wherein the first location corresponds to a first servo track and the second location corresponds to a second servo track. 22. The hard disk drive of claim 21, wherein the seek operation involves a seek time sufficiently long enough to establish a stable acceleration of the transducer. 23. The hard disk drive of claim 22, wherein the sufficiently long enough seek time corresponds to seek lengths greater than approximately 200 servo tracks. 24. The hard disk drive of claim 21, wherein the performance related parameter is determined during each seek operation. 25. The hard disk drive of claim 21, wherein the performance related parameter is determined periodically. 26. The hard disk drive of claim 25, wherein the performance related parameter is determined after every 100 seek operations. 27. A method of adjusting a current profile on the fly during a movement of a transducer, wherein the current profile determines the manner in which current is applied to a voice coil motor so as to move the transducer mounted on an actuator from a first location to a second location, wherein the movement of the transducer comprises an acceleration phase followed by a deceleration phase, the method comprising:applying an acceleration current according to the current profile so as to cause the acceleration of the transducer;determining the peak value of the acceleration current; andadjusting the subsequent portion of the current profile based at least in part on the peak value of the acceleration current. 28. The method of claim 27, wherein applying the acceleration current comprises applying a saturation current. 29. The method of claim 28, wherein determining the peak value of the acceleration current comprises determining the magnitude of the saturation current. 30. The method of claim 29, wherein the magnitude of the saturation current is determined by an analog to digital converter. 31. The method of claim 29, wherein the magnitude of the saturation current is determined inferentially by monitoring the acceleration of the transducer. 32. The method of claim 31, wherein the acceleration of the transducer is determined from monitoring of displacement of the transducer. 33. The method of claim 29, wherein the magnitude of the saturation current is determined by correlating the displacement of the transducer to the magnitude of the saturation current that caused the displacement, wherein the correlation between the displacement and the magnitude of the saturation current is obtained from a lookup table. 34. The method of claim 27, wherein adjusting the subsequent portion of the current profile comprises adjusting the profile of the deceleration current. 35. The method of claim 34, wherein adjusting the profile of the deceleration current comprises increasing the magnitude of the deceleration current so as to utilize more of available current range as determined by the saturation current magnitude. 36. The method of claim 34, wherein adjusting the profile of the deceleration current comprises decreasing the magnitude of the deceleration current. 37. A method of adjusting a current profile that causes movement of a transducer, wherein the current profile has a first portion corresponding to an acceleration phase and a second portion corresponding to a deceleration phase, the method comprising:monitoring a parameter indicative of the movement of the transducer during the application of the first portion of the current profile;determining a performance related parameter based at least in part on the parameter indicative of the movement of the transducer; andadjusting the configuration of the second portion of the current profile based at least in part on the performance rela ted parameter. 38. The method of claim 37, wherein monitoring the parameter indicative of the movement of the transducer comprises monitoring a current that causes the movement of the transducer. 39. The method of claim 38, wherein monitoring the current comprises measuring the current's magnitude using an analog to digital converter. 40. The method of claim 37, wherein monitoring the parameter indicative of the movement of the transducer comprises monitoring the position of the transducer. 41. The method of claim 40, wherein monitoring the parameter indicative of the movement of the transducer further comprises determining the velocity of the transducer based on the rate of change of the position of the transducer. 42. The method of claim 41, wherein the velocity of the transducer is determined by monitoring back-emf induced in the voice coil motor. 43. The method of claim 42, wherein monitoring the parameter indicative of the movement of the transducer further comprises determining the acceleration of the transducer based on the rate of change of the velocity of the transducer. 44. The method of claim 43, wherein monitoring the parameter indicative of the movement of the transducer further comprises determining the current that causes the movement of the transducer based on the acceleration of the transducer, wherein the current is inferred from the acceleration. 45. The method of claim 44, wherein the current is generally linearly proportional to the acceleration. 46. The method of claim 45, wherein determining the performance related parameter comprises determining the magnitude of the current at its peak value. 47. The method of claim 46, wherein determining the magnitude of the current at its peak value comprises determining the magnitude of a saturation current. 48. The method of claim 38, wherein monitoring the current comprises monitoring the displacement of the transducer during a predetermined time interval and correlating the displacement to the saturation current magnitude that caused the displacement. 49. The method of claim 48, wherein the correlation between the displacement and the saturation current magnitude is obtained from a lookup table. 50. The method of claim 37, wherein adjusting the configuration of the second portion of the current profile comprises adjusting the magnitude of peak value of the current of the second portion of the current profile based on the magnitude of peak value of the current of the first portion of the current profile. 51. The method of claim 50, wherein adjusting the configuration of the second portion of the current profile comprises increasing the magnitude of the peak value of the current of the second portion of the current profile. 52. The method of claim 51, wherein increasing the magnitude of the current of the second portion of the current profile comprises increasing the magnitude of the current of the deceleration phase. 53. The method of claim 50, wherein adjusting the configuration of the second portion of the current profile comprises decreasing the magnitude of the peak value of the current of the second portion of the current profile. 54. The method of claim 53, wherein decreasing the magnitude of the current of the second portion of the current profile comprises decreasing the magnitude of the current of the deceleration phase. 55. The method of claim 37, wherein the movement of the transducer is a seek operation.
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