Magnetic Head Gap Control Using Piezo Actuator Touchdown Feedback
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Solution Overview
Problem
In magnetic disk devices, the gap between the magnetic head and the recording medium varies due to the magnetic head moving in directions other than the track direction, leading to instability and potential collisions, which affects the ability to maintain a predetermined desired gap and compromises recording density.
Innovation Solution
A disk device with a magnetic head, a suspension assembly, and a micro actuator using piezoelectric elements to adjust the gap, controlled by a controller that sets the drive voltage based on touchdown outputs during actuator operation, ensuring the gap remains stable and within a predetermined target value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a micro actuator is used to perform fine tuning of the magnetic head position, then positioning precision is improved, but the gap between the magnetic head and recording medium varies causing instability
Solution Approach 1:
The system measures the actual gap between the magnetic head and recording medium using a measurement unit, compares it with the target gap value, and uses the difference to adjust the micro actuator's drive voltage through a control unit, forming a closed-loop feedback system that maintains gap stability while enabling fine positioning
Solution Approach 2:
The system dynamically adjusts the drive voltage parameter of the piezoelectric element based on the measured gap deviation, changing the electrical parameter to compensate for positional deviations and maintain the desired gap distance
2Productivity
If the gap between magnetic head and recording medium is reduced to improve recording density, then productivity is improved, but the risk of collision increases reducing reliability
Solution Approach 1:
The system performs preliminary measurement of the actual gap distance before recording operations, and pre-adjusts the micro actuator positioning based on the measured value to ensure the gap remains within the safe range, preventing collision before it occurs
Solution Approach 2:
The measurement unit continuously monitors the gap distance and provides feedback to the control unit, which adjusts the micro actuator in real-time to maintain the gap within the optimal range for both high recording density and collision prevention
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively maintains a consistent gap between the magnetic head and the recording medium, reducing the risk of collisions and enhancing recording density by stabilizing the magnetic head's position, thereby improving the reliability and performance of the disk device.
Implementation Method 1
a micro actuator including a piezoelectric element provided on the suspension assembly
Implementation Method 2
a heater configured to adjust a gap between the magnetic head and the recording medium
Data Source
AI summary
According to one embodiment, a disk device includes a disk-shaped recording medium, a magnetic head including a write head, a read head, and a heater configured to adjust a gap between the magnetic head and the recording medium, a suspension assembly supporting the magnetic head, a micro actuator including a piezoelectric element on the suspension assembly, and a controller configured to set a drive voltage of the piezoelectric element in accordance with a difference between a touchdown output in time of driving the piezoelectric element and a touchdown output in time of non-driving the piezoelectric element.