Magnetic Head Thermal Actuators for Flying Height Stability
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Solution Overview
Problem
In magnetic disk devices, the gap between the magnetic head and the recording medium varies with temperature and radial position, leading to instability in recording density and potential head damage due to changing flying height.
Innovation Solution
A disk device with a temperature sensor and pressure sensor that adjusts the power ratio between first and second thermal actuators to control the protrusion of the write and read heads, maintaining optimal flying height across different temperatures and radial positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a thermal actuator is used to reduce the gap between the head and recording medium, then recording density is improved, but flying height becomes unstable due to temperature and radial position changes
Solution Approach 1:
The patent employs two independent thermal actuators (first and second thermal actuators) that can be dynamically controlled with different drive powers. This dynamic control system adjusts the protrusion amounts of the write head and read head independently based on temperature and radial position conditions, resolving the contradiction between achieving small gap for high density and maintaining stable flying height.
Solution Approach 2:
The controller changes the drive power parameters supplied to the thermal actuators based on detected temperature and radial position. By adjusting these power parameters dynamically, the system compensates for environmental variations and maintains stable flying height while achieving the required small gap for high recording density.
2Productivity
If the gap is reduced to improve recording density, then linear recording density increases, but the head may contact the recording medium causing damage
Solution Approach 1:
The patent uses sensors to detect temperature and radial position, providing feedback to the controller. Based on this feedback, the controller adjusts the drive power to the thermal actuators in real-time, ensuring the flying height remains stable and the head does not contact the recording medium, thus preventing damage while maintaining high recording density.
Solution Approach 2:
The system proactively adjusts the flying height based on predicted temperature and radial position changes before head contact can occur. By compensating for these variations in advance through controlled protrusion adjustment, the system prevents harmful contact while maintaining optimal recording conditions.
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
This solution stabilizes the flying height of the magnetic heads, maintaining recording density and preventing head damage by dynamically adjusting the power ratio based on temperature and radial position changes, thereby enhancing reliability and performance.
Implementation Method 1
causing a part of the slider to bulge, the read head, and the recording head toward the surface side of the recording medium by the thermal actuator
Data Source
AI summary
According to one embodiment, a disk device includes a housing, a temperature sensor in the housing, a magnetic disk in the housing, a magnetic head disposed in the housing to be movable in a radial direction of the magnetic disk, the magnetic head including a write head, a read head, a first thermal actuator, and a second thermal actuator, a power supply circuit which supplies first power to the first thermal actuator and supplies second power to the second thermal actuator, and a controller configured to adjust a power ratio between the first power and the second power, based on at least one of a change in temperature inside the housing and a change in a radial position of the magnetic head in the radial direction.