Disk Drive Read Write Offset Correction
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Solution Overview
Problem
In disk drives, mechanical displacement after shipment can cause data to be recorded at a position different from the desired position, leading to incorrect reading of data written on the disk, as existing read offset correction methods do not guarantee accurate data recording.
Innovation Solution
A disk drive system that includes a control unit to calculate the offset shift amount between the read and write heads and corrects the position of the head using a position correction value, ensuring accurate data writing and reading by moving the head to the desired position based on initial offset values stored in nonvolatile memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If read offset correction is performed based on initial offset values, then data reading is enabled, but mechanical displacement after shipment causes data to be recorded at incorrect positions
Solution Approach 1:
The patent performs offset correction in advance before data writing occurs. The control unit calculates a position correction value based on the difference between initial and current offset values, and applies this correction before the head writes data to the disk. This preliminary correction ensures that even if mechanical displacement occurs after shipment, the data will be recorded at the correct position.
Solution Approach 2:
The patent implements a feedback mechanism where the control unit continuously monitors the actual offset value and compares it with the initial offset value stored in nonvolatile memory. Based on this feedback, the control unit calculates the necessary position correction and adjusts the head position accordingly, ensuring accurate data recording despite mechanical displacement.
2Manufacturing precision
If the head position is corrected using position correction value, then data recording position accuracy is improved, but the system complexity increases
Solution Approach 1:
The control unit automatically performs the position correction process without external intervention. It retrieves the initial offset value from nonvolatile memory, calculates the current offset value, determines the position correction value, and applies the correction to the head position autonomously. This self-service approach minimizes the need for additional complex external correction mechanisms.
Solution Approach 2:
The patent changes the offset value parameter dynamically based on mechanical displacement conditions. The control unit adjusts the head position by applying a position correction value that compensates for changes in the offset parameter, allowing the system to adapt to mechanical displacement without requiring complex structural modifications.
Data Source
AI summary
A disk drive according to an embodiment includes a disk, a first actuator having a first arm, a second actuator having a second arm, and a head. The head includes a write head and a read head. In addition, the disk drive includes a control unit calculating an amount of shift from an initial value of offset in a radial direction of the disk between the read head and the write head. The control unit controls the second actuator and corrects a position of the head to a position where the shift amount is reduced.