[미국특허]
Disk drive with efficient coil temperature estimation
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
G11B-005/55
G11B-033/14
출원번호
US-0796920
(2001-02-28)
발명자
/ 주소
Messenger, Carl R.
Nguyen, David D.
출원인 / 주소
Western Digital Technologies, Inc.
대리인 / 주소
Shara, Esq. Milad G.
인용정보
피인용 횟수 :
149인용 특허 :
5
초록▼
A controller for a disk drive that accesses a look up table having a plurality of thermally characterized values corresponding to a plurality of seek operations. For each seek operation, the corresponding value is added to a register. The controller decrements the register at a rate that is determin
A controller for a disk drive that accesses a look up table having a plurality of thermally characterized values corresponding to a plurality of seek operations. For each seek operation, the corresponding value is added to a register. The controller decrements the register at a rate that is determined using servo interrupts occurring as a result of the rotation of the disk. When the value of the register exceeds a threshold, the controller adjusts the subsequent seek operation so as to inhibit damage to the voice coil as a result of overheating.
대표청구항▼
1. A method of inhibiting a voice coil of a hard disk drive from overheating, the method comprising:performing a plurality of seek operations;adjusting a value stored in a register by amounts which are indicative of the heat which is produced in the voice coil during the plurality of seek operations
1. A method of inhibiting a voice coil of a hard disk drive from overheating, the method comprising:performing a plurality of seek operations;adjusting a value stored in a register by amounts which are indicative of the heat which is produced in the voice coil during the plurality of seek operations;continually counter-adjusting the adjusted value stored in the register while the plurality of the seek operations are performed, wherein the counter-adjusting occurring at a rate which is determined by a substantially periodic signal; andmodifying seek operations when the value of the register is outside of a preferred range. 2. The method of claim 1, wherein adjusting a value stored in a register comprises increasing the value stored in the register. 3. The method of claim 2, wherein counter-adjusting the value stored in the register comprises decreasing the value stored in the register. 4. The method of claim 1, wherein counter-adjusting the value stored in the register comprises counter-adjusting the value stored in the register at a rate which is determined by the rotational speed of a disk of the drive. 5. The method of claim 1, wherein said substantially periodic signal comprises a plurality of interrupts. 6. The method of claim 5, wherein said plurality of interrupts are generated in response to an input clock signal. 7. The method of claim 5, wherein said plurality of interrupts are generated in response to a transducer of the drive passing a plurality of servo wedges of a disk of the drive. 8. The method of claim 5, wherein said periodic signal has a period which is determined by the rotational speed of a disk of the drive. 9. The method of claim 8, wherein the period of the periodic signal is substantially equal to an amount of time that is required for first and second servo wedges of a disk of the drive to pass by a transducer of the drive. 10. The method of claim 1, wherein counter-adjusting the value comprises decreasing the value stored in the register in response to a servo wedge of the disk passing a transducer of the drive. 11. The method of claim 1, wherein adjusting a value stored in a register by amounts which are indicative of the heat which is produced in the voice coil during the plurality of seek operations comprises increasing the value of the register by amounts which are determined by the seek lengths of the plurality of seek operations. 12. The method of claim 1, wherein adjusting a value stored in a register by amounts which are indicative of the heat which is produced in the voice coil during the plurality of seek operations comprises accumulating estimated heat dissipation time periods in the register. 13. The method of claim 1, wherein counter-adjusting the value comprises counter-adjusting the value during said plurality of seek operations. 14. The method of claim 1, wherein counter-adjusting the value comprises counter-adjusting the value during a track following operation. 15. The method of claim 1, wherein modifying seek operations comprises delaying subsequent seek operations. 16. The method of claim 15, wherein delaying subsequent seek operations comprises delaying subsequent seek operations until the value of the register is within the preferred range. 17. The method of claim 15, wherein delaying subsequent seek operations comprises delaying subsequent seek operations for a fixed period of time. 18. The method of claim 1, wherein modifying seek operations comprises providing the coil with a reduced average current. 19. The method of claim 1, wherein modifying seek operations when the value of the register is outside of a preferred range comprises modifying seek operations when the value of the register is greater than a threshold value. 20. The method of claim 19, wherein modifying seek operations when the value of the register is greater than a threshold value comprises modifying seek operations when the value of the register is greater than the threshold value which is determined by (a) p erforming a plurality of maximally heating seek operations on a substantially identical hard drive, and (b) extracting the value of the register of the substantially identical hard drive when the temperature of the coil of the substantially identical hard drive reaches a threshold temperature. 21. A method of inhibiting a voice coil of a hard disk drive from overheating, the method comprising:performing a plurality of seek operations so as to reposition a transducer adjacent a recording medium a plurality of times, wherein each seek operation adds heat to the coil;determining a plurality of thermally characterized values, wherein each thermally characterized value is indicative of the heat that is added to the coil during a corresponding seek operation of the plurality of seek operations;accumulating the plurality of thermally characterized values in a register;continually reducing the value stored in the register while the plurality of the seek operations are performed; andmodifying seek operations when the value of the register is greater than a threshold value. 22. The method of claim 21, wherein each of the plurality of thermally characterized values is an estimate of a time period that is required for the heat added to the coil during the corresponding seek operation to dissipate away from the coil. 23. The method of claim 21, wherein determining a plurality of thermally characterized values comprises using a lookup table. 24. The method of claim 23, wherein using a lookup table comprises using an x-y lookup table that correlates an estimated heat dissipation duration (y) to a seek length (x). 25. The method of claim 24, further comprising initializing the lookup table so as to define (a) a positively sloped line that begins at a first point (x 1 ,y 1 ) and extends to a second point (x 2 ,y 2 ), and (b) a horizontal line that extends from the second point. 26. The method of claim 25, further comprising equating x 2 with a seek length of a maximally heating seek operation such that the transducer is substantially always accelerating or decelerating and the transducer reaches a maximally allowed speed during the maximally heating seek operation. 27. The method of claim 25, further comprising determining y 2 by performing a plurality of maximally heating seek operations on a substantially identical hard disk drive such that a delay period, Δt, is introduced between successive seek operations so as to maintain the temperature of the substantially identical hard drive at a constant elevated value. 28. The method of claim 27, wherein determining y 2 further comprises equating y 2 to the time duration of a maximally heating seek operation plus Δt. 29. The method of claim 21, wherein accumulating the plurality of thermally characterized values in a register comprises adding the plurality of thermally characterized values to the register. 30. The method of claim 29, wherein adding the plurality of thermally characterized values to the register comprises adding the plurality of thermally characterized values so as to be synchronous with said performing a plurality of seek operations. 31. The method of claim 21, wherein continually reducing the register comprises periodically reducing the value stored in the register at a substantially constant rate. 32. The method of claim 21, wherein continually reducing the register comprises periodically subtracting a plurality of elapsed times from the register. 33. The method of claim 32, wherein each of the plurality of elapsed times is the time required for adjacent servo wedges of the recording medium to pass by the transducer. 34. The method of claim 21, wherein continually reducing the register further comprises responding to a plurality of interrupts. 35. A hard disk drive comprising:a magnetic medium;a transducer that interacts with the magnetic medium;an actuator comprising a voice coil that accelerates the transducer; anda control system comprising a register, wherein the control system instructs the actuator to perform a plurality of seek operations so as to reposition the transducer between a plurality of locations adjacent the magnetic medium, wherein the register stores a value which is indicative of the thermal energy of the coil, wherein the control system adjusts the value of the register according to the plurality of seek operations so as to account for heat added to the coil during the plurality of seek operations, wherein the control system continually counter-adjusts the adjusted value of the register while the plurality of the seek operations are performed to account for heat that dissipates away from the coil, and wherein the control system modifies subsequent seek operations when the value stored in the register is outside of a preferred range so as to reduce the rate at which heat is added to the coil. 36. The drive of claim 35, wherein the value stored in the register is an estimated amount of time that is required for the coil to cool down to a preferred temperature. 37. The drive of claim 35, wherein the control system adjusts the value stored in the register by increasing the value stored in the register in correspondence with each of the plurality of seek operations, wherein each increase adds a period of time which is an estimate of the time that is required for the heat added during the corresponding seek operation to dissipate away from the coil. 38. The drive of claim 37, wherein the control system counter-adjusts the value stored in the register by periodically reducing the value stored in the register so as to account for the passing of time. 39. The drive of claim 35, wherein the magnetic medium comprises a plurality of servo wedges that provide the control system with a substantially periodic signal, wherein the control system counter-adjusts the value stored in the register according to the substantially periodic signal. 40. The drive of claim 35, wherein the control system modifies subsequent seek operations by delaying subsequent seek operations. 41. The drive of claim 35, wherein the voice coil accelerates the transducer when a current flows through the voice coil and wherein the control system modifies subsequent seek operations by reducing the current that flows through the voice coil. 42. The drive of claim 35, wherein the control system further comprises a memory that stores a lookup table which correlates a heat dissipation time period (y) to a seek length (y). 43. The drive of claim 35, wherein the lookup table is defined by (a) a positively sloped line that begins at a first point (x 1 ,y 1 ) and extends to a second point (x 2 ,y 2 ), and (b) a horizontal line that extends from the second point. 44. The drive of claim 43, wherein x 2 is substantially equal to the seek length of a maximally heating seek operation such that the transducer is substantially always accelerating or decelerating and the transducer reaches a maximally allowed speed during the maximally heating seek operation. 45. The drive of claim 44, wherein y 2 is substantially equal to the time duration of a maximally heating seek operation plus a delay period, Δt, which is determined by performing a plurality of maximally heating seek operations on a substantially identical hard disk drive such that the delay period, Δt, is introduced between successive maximally heating seek operations so as to maintain the temperature of the substantially identical hard drive at a constant elevated value. 46. The drive of claim 35, wherein the control system modifies subsequent seek operations when the value stored in the register is greater than a threshold value. 47. The drive of claim 46, wherein the threshold value is determined by (a) performing a plurality of maximally heating seek operations on a substantially identical hard drive, and (b) extracting the value of the register of the substantially identical hard drive when the temperature of the coil of the substantially identical ha rd drive reaches a threshold temperature.
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