Magnetic Head Thermal Expansion Control
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Solution Overview
Problem
In magnetic recording devices, the close proximity of the reading and recording parts on a magnetic head is challenging due to thermal expansion issues, where heat from the reading part expansion heater can cause the recording part to contact the magnetic recording medium before the reading part, preventing accurate adjustment of the reading distance and leading to capacity loss.
Innovation Solution
A magnetic head design with a thermal expansion promoting layer positioned closer to the reading part than the recording part, allowing independent heating of both parts, and a protective layer with varying thicknesses to manage thermal expansion and maintain optimal distances between the reading and recording parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reading part and recording part are arranged close to each other on the magnetic head, then the capacity loss of the magnetic recording medium is reduced, but heat from the reading part expansion heater causes the recording part to contact the magnetic recording medium before the reading part, preventing accurate adjustment of the reading distance
Solution Approach 1:
The magnetic head is divided into functionally independent heating zones: a reading part expansion heater specifically for the reading part and a recording part expansion heater specifically for the recording part. This segmentation allows independent thermal control of each part, enabling the reading part to be heated and expanded without causing unwanted expansion of the recording part, thus maintaining precise distance adjustment capability while keeping parts close together.
Solution Approach 2:
Different thermal properties are applied to different regions of the magnetic head. The reading part is equipped with its own expansion heater and is designed with specific thermal characteristics to respond to localized heating, while the recording part has different thermal properties and its own separate heater. This local differentiation allows the reading part to be thermally controlled without affecting the recording part's position, resolving the contradiction between close arrangement and independent control.
2Manufacturing precision
If the reading part is heated to expand and reduce distance to the magnetic recording medium, then reading performance is improved, but the recording part may also expand due to heat transfer, causing it to contact the medium first
Solution Approach 1:
The heating system is segmented into separate reading part expansion heater and recording part expansion heater. This allows heat to be applied locally to the reading part without significantly heating the recording part, enabling precise distance control for reading while minimizing thermal interference with the recording part's position.
Solution Approach 2:
A thermal isolation structure or air gap is introduced between the reading part and recording part to act as a thermal mediator. This intermediary prevents heat from the reading part expansion heater from transferring to the recording part, allowing independent thermal control and preventing unwanted expansion of the recording part when the reading part is heated.
3Ease of operation
If the distance between reading part and recording part is increased to prevent thermal interference, then distance adjustment control is improved, but the capacity loss of the magnetic recording medium increases
Solution Approach 1:
By segmenting the heating system into independent reading part and recording part heaters, the magnetic head can maintain a compact arrangement with both parts close together while still achieving independent distance control. The segmentation eliminates the need for large spacing that would be required if thermal interference were the only control mechanism, thus preserving recording capacity while maintaining operational control.
Solution Approach 2:
The thermal parameters (heating power, heating duration, thermal conductivity) are independently controlled for each part through separate heaters. This allows the system to maintain close spacing between reading and recording parts while using parameter changes in the heating control to prevent thermal interference, thereby preserving both compact arrangement and operational control.
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 design enables precise adjustment of the reading part's distance to the magnetic recording medium, maintaining reading performance while preventing capacity loss by ensuring the reading part can be brought closer without the recording part interfering, thus enhancing the magnetic recording medium's capacity and accuracy.
Implementation Method 1
resistive heating bodies are respectively prepared in the vicinity of a recording part and the vicinity of a reading part
Implementation Method 2
bring the recording part, when recording, and the reading part, when reading, close to the magnetic recording medium
Implementation Method 3
resistive heating bodies are respectively prepared in the vicinity of a recording part and the vicinity of a reading part
Implementation Method 4
bring the recording part, when recording, and the reading part, when reading, close to the magnetic recording medium
Implementation Method 5
a method (near-field light heating) is proposed in which the laser light is converted to near-field light and the magnetic recording medium is heated by irradiating the magnetic recording medium with the near-field light
Implementation Method 6
so-called thermally-assisted magnetic recording is proposed in which a magnetic material with large magnetic anisotropy energy Ku is used as a recording medium and a magnetic field is applied to perform writing after a coercive force is reduced by applying heat to the magnetic recording medium
Implementation Method 7
The evanescent light and collective oscillations of electric charges in the plasmon generator are coupled and surface plasmons are excited in the plasmon generator
Implementation Method 8
light that is referred to as evanescent light and exudes to the cladding layer is generated. The evanescent light and collective oscillations of electric charges in the plasmon generator are coupled
Implementation Method 9
it is possible that not only heat generation of a recording part expansion heater and a reading part expansion heater, but also the irradiation of the near-field light can cause temperature rise and thermal expansion in the magnetic head
Data Source
AI summary
A magnetic head includes a reading part, a recording part that is laminated on the reading part in a planer view, a recording part expansion heater, a reading part expansion heater, and a thermal expansion promoting layer that is prepared at a position closer to the reading part than to the recording part and extends to an air bearing surface.