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US 2014/0177086 A1Published application
Disk Drive with Servo System with Timing Adjustments to Master Timer for SAM Detection Errors
AssigneeHGST Netherlands B.V.
InventorsGary Allan Herbst, Kirk Hwang, Masaki Kohno, Naoyuki Minami, Hung Phan
Life of this patent
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Abstract
A disk drive is described with a single servo master timer that is used to control timing critical signals such as servo gate, SAM windows, channel power save, PREAMP power save and so on. The master timer is adjusted to compensate for SAM detection errors (early, late or missed) and provides improved servo timing quality. In an embodiment the adjustable master timer can be selectably clocked by either the DLC/DSW clock or the system clock.
Claims18
A method of operating a disk drive comprising:
- timing a servo gate control signal and a servo address mark (SAM) search window from a master timer;
- using the master timer to measure a SAM-SAM time interval between consecutive SAM detections by saving a current master timer value and resetting the master timer when a SAM is detected;
- and
- adjusting the current master timer value when SAM detection fails to occur in a selected normal region of the SAM search window by changing the current master timer value to adjust for early, late or missing SAM detection by adding an adjustment amount to the current master timer value or subtracting the adjustment amount from the current master timer value.
1 more element
A method of operating a disk drive comprising:
- timing a servo gate control signal and a servo address mark (SAM) search window from a master timer;
- using the master timer to measure a SAM-SAM time interval between consecutive SAM detections by saving a current master timer value and resetting the master timer when a SAM is detected;
- and
- adjusting the current master timer value when SAM detection fails to occur in a selected normal region of the SAM search window by changing the current master timer value to adjust for early, late or missing SAM detection;
- wherein adjusting the current master timer value for a late SAM detection further comprises determining a positive time delta between an ideal SAM detection point and the master timer value when the late SAM was detected and adding the positive time delta to the current master timer value.
2 more elements
A method of operating a disk drive comprising:
- timing a servo gate control signal and a servo address mark (SAM) search window from a master timer;
- using the master timer to measure a SAM-SAM time interval between consecutive SAM detections by saving the current master timer value and resetting the master timer when a SAM is detected;
- and
- adjusting the current master timer value when SAM detection fails to occur in a selected normal region of the SAM search window by changing the current master timer value to adjust for early, late or missing SAM detection;
- wherein adjusting the current master timer value for an early SAM detection further comprises determining a positive time delta between the current master timer value when the early SAM was detected and an ideal SAM detection point and subtracting the positive time delta from the current master timer value.
2 more elements
A method of operating a disk drive comprising:
- timing a servo gate control signal and a servo address mark (SAM) search window from a master timer;
- using the master timer to measure a SAM-SAM time interval between consecutive SAM detections by saving the current master timer value and resetting the master timer when a SAM is detected;
- and
- adjusting the current master timer value when SAM detection fails to occur in a selected normal region of the SAM search window by changing the current master timer value to adjust for early, late or missing SAM detection;
- wherein changing the current master timer value further comprises reading the current master timer value, adding to or subtracting an amount from the current master timer value to generate an adjusted value and reloading the adjusted value into the master timer.
2 more elements
A method of operating a disk drive comprising:
- timing a servo gate control signal and a servo address mark (SAM) search window from a master timer;
- using the master timer to measure a SAM-SAM time interval between consecutive SAM detections by saving the current master timer value and resetting the master timer when a SAM is detected;
- and
- adjusting the current master timer value when SAM detection fails to occur in a selected normal region of the SAM search window by changing the current master timer value to adjust for early, late or missing SAM detection;
- wherein a selected power saving mode is timed using the master timer and selected power saving mode is selectably entered between servo gate control signal assertions when user data is not being read or written.
2 more elements
A disk drive with a servo system comprising:
- a master timer used for timing a servo gate control signal and a servo address mark (SAM) search window, the master timer being used to measure a SAM-SAM time interval between consecutive SAM detections by saving the current master timer value and resetting the master timer when a SAM is detected;
- and
- timer controls that adjust the current master timer value when SAM detection fails to occur in a selected normal region of the SAM search window by changing the current master timer value to adjust for early, late or missing SAM detection by adding an adjustment amount to the current master timer value or subtracting the adjustment amount from the current master timer value.
A disk drive with a servo system comprising:
- a master timer used for timing a servo gate control signal and a servo address mark (SAM) search window, the master timer being used to measure a SAM-SAM time interval between consecutive SAM detections by saving the current master timer value and resetting the master timer when a SAM is detected;
- and
- timer controls that adjust the master timer when SAM detection fails to occur in a selected normal region of the SAM search window by changing the current master timer value to adjust for early, late or missing SAM detection;
- wherein the timer controls adjust the master timer for a late SAM detection by determining a positive time delta between an ideal SAM detection point and the current master timer value when the late SAM was detected and adding the positive time delta to the current master timer value.
1 more element
A disk drive with a servo system comprising:
- a master timer used for timing a servo gate control signal and a servo address mark (SAM) search window, the master timer being used to measure a SAM-SAM time interval between consecutive SAM detections by saving the current master timer value and resetting the master timer when a SAM is detected;
- and
- timer controls that adjust the master timer when SAM detection fails to occur in a selected normal region of the SAM search window by changing the current master timer value to adjust for early, late or missing SAM detection;
- wherein the timer controls adjust the master timer for an early SAM detection by determining a positive time delta between the current master timer value when the early SAM was detected and an ideal SAM detection point and subtracting the positive time delta from the current master timer value.
1 more element
A disk drive with a servo system comprising:
- a master timer used for timing a servo gate control signal and a servo address mark (SAM) search window, the master timer being used to measure a SAM-SAM time interval between consecutive SAM detections by saving the current master timer value and resetting the master timer when a SAM is detected;
- and
- timer controls that adjust the master timer when SAM detection fails to occur in a selected normal region of the SAM search window by changing [fall the current master timer value to adjust for early, late or missing SAM detection;
- wherein changing the current master timer value further comprises reading the current master timer value, adding an adjustment amount to the current master timer value or subtracting the amount from the current master timer value to generate an adjusted value and reloading the adjusted value into the master timer.
1 more element
A disk drive with a servo system comprising:
- a master timer used for timing a servo gate control signal and a servo address mark (SAM) search window, the master timer being used to measure a SAM-SAM time interval between consecutive SAM detections by saving the current master timer value and resetting the master timer when a SAM is detected;
- and
- timer controls that adjust the master timer when SAM detection fails to occur in a selected normal region of the SAM search window by changing the current master timer value to adjust for early, late or missing SAM detection;
- wherein a selected power saving mode is timed using the master timer and selected power saving mode is selectably entered between servo gate control signal assertions when user data is not being read or written.
1 more element
Dependencies are inferred from the claim text.