Thermal Actuator Head Gap Control for Magnetic Disk Reliability
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Solution Overview
Problem
Magnetic disk devices face challenges in reducing the gap between the read/write head and the magnetic disk to enhance recording density, as existing thermal actuators struggle to maintain a consistent gap, leading to wear and contamination issues while compromising recording density.
Innovation Solution
A magnetic disk device incorporating a thermal actuator and a gap sensor to control the projection of the head surface onto the magnetic disk, adjusting the gap with high accuracy by using a heater to maintain a desired distance, ensuring reliable operation and improved recording density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the gap between the read/write head and magnetic disk is decreased to improve recording density, then recording density is improved, but the thermal actuator cannot maintain a consistent gap leading to head wear and contamination
Solution Approach 1:
The patent employs a feedback control system where a gap sensor continuously measures the actual gap between the head and disk surface, and this measurement is fed back to the thermal actuator controller. The controller adjusts the thermal actuator's projection amount based on the detected gap, maintaining the gap within a predetermined range even when the disk surface has irregularities, thus preventing head wear and contamination while enabling reduced gap operation for improved recording density
Solution Approach 2:
The patent replaces conventional mechanical gap control mechanisms with a thermal actuator system. The thermal actuator uses thermal expansion/contraction to dynamically adjust the head's projection amount onto the disk, providing precise and responsive gap control without mechanical contact, thereby maintaining reliability while achieving the reduced gap necessary for high recording density
2Length of stationary object
If a thermal actuator is used to project the head surface to the magnetic disk, then the gap can be reduced, but the gap becomes inconsistent leading to wear and contamination
Solution Approach 1:
The gap sensor continuously detects the actual gap distance between the head and disk, providing real-time feedback to the control system. This feedback enables dynamic adjustment of the thermal actuator to maintain consistent gap distance, compensating for disk surface irregularities and preventing the inconsistency that would otherwise cause wear and contamination
Solution Approach 2:
The patent dynamically changes the thermal actuator's physical state (temperature/expansion) based on detected gap conditions. By adjusting the thermal actuator's projection amount in response to gap variations, the system maintains stable and consistent gap distance despite variations in disk surface topology, thereby improving gap consistency
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 head and the magnetic disk, enhancing recording density, preventing wear, and reducing contamination, thereby improving the overall performance and reliability of the magnetic disk device.
Implementation Method 1
a thermal actuator configured to project a head surface of the magnetic head to a recording surface of the magnetic disk
Data Source
AI summary
According to one embodiment, a magnetic disk device includes a magnetic disk, a magnetic head including a read head to read data from the magnetic disk and a write head to write data to the magnetic disk, and a controller configured to control read/write from/to the magnetic disk by the magnetic head. The magnetic head includes a thermal actuator configured to project a head surface of the magnetic head to a recording surface of the magnetic disk, and a detector configured to detect a gap between the head surface and the recording surface of the magnetic disk. The controller controls a degree of projection of the magnetic head to the recording surface by the thermal actuator corresponding to the gap detected by the detector during the read/write.