Stepped-Back Thermal Asperity Sensor for Disk Contact Detection
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Solution Overview
Problem
Existing magnetic head technologies face challenges in detecting unintentional projections on magnetic disks without damaging sensors, maintaining physical reliability and corrosion resistance, and ensuring the air bearing surface remains unaffected in shape and size.
Innovation Solution
A magnetic head with a sensor positioned in a stepped-back position from the air bearing surface, covered by an insulating film, and connected via lead films that transfer temperature changes for detection, along with a heater for controlling flying height through heat expansion, ensuring the sensor's electrical resistance varies with temperature changes without direct contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor is positioned on the air bearing surface to detect contact, then detection sensitivity is improved, but the sensor may contact the magnetic disk and suffer damage
Solution Approach 1:
The sensor is repositioned from the air bearing surface to a stepped-back position on the slider body, changing its spatial dimension. This allows the sensor to detect temperature changes through thermal conduction from the air bearing surface via the lead film, without being exposed to direct contact with the magnetic disk, thus resolving the contradiction between detection sensitivity and sensor reliability
2Reliability
If the sensor is positioned away from the air bearing surface to protect it, then sensor reliability is improved, but detection sensitivity deteriorates
Solution Approach 1:
A lead film is introduced as an intermediary thermal conduction path between the air bearing surface and the sensor. The lead film transfers temperature changes from the air bearing surface to the sensor positioned on the slider body, enabling the sensor to detect contact indirectly without being exposed to the magnetic disk, thus maintaining both reliability and detection sensitivity
3Adaptability or versatility
If a separate projection detection head is added, then projection detection capability is improved, but device complexity increases
Solution Approach 1:
The magnetic head is designed with multi-functionality by integrating both the reproducing element and the projection detection sensor into a single device. The sensor on the air bearing surface serves dual purposes: detecting contact during normal operation and detecting projections on the magnetic disk, eliminating the need for a separate projection detection head and reducing device complexity
4Productivity
If the reproducing element is positioned for optimal information reproduction, then reproduction performance is improved, but its ability to detect contact deteriorates
Solution Approach 1:
The detection function is segmented from the reproducing element and assigned to a separate sensor on the air bearing surface. This allows the reproducing element to be optimally positioned for information reproduction while the sensor independently performs contact and projection detection, resolving the contradiction between reproduction performance and contact detection ability
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 configuration allows for accurate detection of contact and control of flying height without impairing sensor reliability or air bearing surface integrity, enhancing detection sensitivity and efficiency while maintaining sensor protection.
Implementation Method 1
a pair of lead films, the lead films being electrically connected to the sensor such that at least portions of the lead films are exposed on the air bearing surface, and being configured to transfer a temperature change of the air bearing surface to the sensor
Implementation Method 2
a heater that is provided in the slider and that decreases a flying height of the magnetic head from the magnetic disk due to a heat expansion of the slider
Implementation Method 3
detects a resistance change corresponding to frictional heat generated by contact between the projection detection head and the magnetic disk
Data Source
AI summary
A magnetic head disposed in a slider arranged with an interval with respect to a magnetic disk includes a sensor that is positioned in a stepped-back position from an air bearing surface facing the magnetic disk, an insulating film that is positioned on the air bearing surface and that covers the sensor; a pair of lead films, the lead films being electrically connected to the sensor such that at least portions of the lead films are exposed on the air bearing surface, and being configured to transfer a temperature change of the air bearing surface to the sensor.