Magnetic Head Contact Sensor with Extended Leads
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Solution Overview
Problem
Current magnetic data recording systems face challenges in detecting head-to-disk contact with high precision, limiting the reduction of magnetic spacing and potentially causing damage due to indirect detection methods.
Innovation Solution
A contact sensor with a temperature-sensitive sensor film and leads extending beyond the air bearing surface, constructed from NiFe alloys for high temperature coefficient of resistance and corrosion resistance, and Ru, Rh, or Ta for lead materials, to detect contact with sensitivity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If indirect detection methods are used for head-to-disk contact, then the system complexity is reduced, but the measurement precision of contact detection deteriorates
Solution Approach 1:
The patent replaces indirect mechanical detection methods with a direct electrical resistance-based detection system. The contact sensor uses a sensor film whose electrical resistance changes in response to contact conditions, substituting mechanical sensing with electrical property measurement for more precise and direct contact detection.
Solution Approach 2:
The invention utilizes changes in electrical resistance as a parameter to detect contact. By monitoring the resistance change of the sensor film when contact occurs, the system achieves precise detection through parameter variation rather than complex mechanical sensing arrangements.
2Productivity
If magnetic spacing is reduced to increase recording density, then productivity is improved, but the risk of head-to-disk contact damage increases
Solution Approach 1:
The contact sensor provides real-time feedback on head-to-disk contact conditions by detecting resistance changes. This feedback mechanism allows the system to monitor spacing conditions and prevent damage by detecting contact events, enabling safer operation at reduced magnetic spacing for higher recording density.
Solution Approach 2:
The sensor film is positioned to make contact with the disk surface before the magnetic head components. This preliminary contact arrangement allows the sensor to detect approaching contact conditions first, providing early warning before actual damage can occur to the expensive magnetic head or disk.
3Measurement precision
If a contact sensor with sensor film exposed at air bearing surface is used, then measurement precision is improved, but the sensor film wears out quickly reducing reliability
Solution Approach 1:
The sensor film is designed as a sacrificial element that can wear or degrade over time. By using a relatively simple and replaceable sensor film rather than a complex permanent sensor, the system achieves precise contact detection while accepting that the film may need replacement after extended use, balancing precision with practical durability.
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 enables precise and durable contact detection, minimizing wear and noise, and maintaining reliable performance even after numerous head/disk contacts, thereby enhancing recording density and system longevity.
Implementation Method 1
a sensor film having an electrical resistance that changes in response to a change in temperature
Implementation Method 2
thermal actuators can be incorporated into a head to decrease the fly height and thus magnetic spacing through thermal expansion of the read and write head components
Implementation Method 3
when the disk rotates air is swirled by the rotating disk and thus lifts the slider above the disk
Data Source
AI summary
A thermally actuated head for magnetic head for magnetic data recording having a contact sensor for detecting contact between the head and a magnetic disk. The contact sensor includes a thermal sensor film and first and second leads, wherein the leads extend at least as far from the ABS as the thermal sensor film. More preferably the leads extend slightly further from the ABS than the sensor film so that contact between the magnetic disk and the contact sensor occurs at the leads rather than at the sensor film. The sensor film can be constructed of NiFe, preferably having 30-70 atomic percent Ni or more preferably 40-60 atomic percent Ni or most preferably 40-50 atomic percent Ni. The leads are preferably constructed of one or more of Ru, Rh or Ta or an alloy whose primary constituents are Ru, Rh or Ta.