Spin-Torque Oscillator Write Head for Contact Detection
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Solution Overview
Problem
Current technologies in hard disk drives (HDDs) lack an effective method for writer-to-disk contact detection and spacing sensing, which is crucial for maintaining optimal head-to-disk clearance and preventing reliability issues due to repeated contact or fly height changes, especially as bit densities increase.
Innovation Solution
A write head device incorporating a spin-torque oscillator (STO) is placed between the main pole tip and a surrounding magnetic shield, with resistance measurements used to detect writer-to-disk spacing and contact, enabling precise control and detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If head to disk clearance is decreased to increase bit densities, then recording precision is improved, but reliability deteriorates due to repeated head to disk contact
Solution Approach 1:
The patent implements preliminary detection of head-to-disk contact and spacing changes before they cause reliability failures. The sensor detects contact and spacing parameters in advance, allowing the system to take preventive actions such as adjusting fly height or alerting operators before repeated contact occurs, thus resolving the contradiction between decreased clearance for precision and reliability concerns
2Manufacturing precision
If head to disk clearance is decreased for higher bit densities, then recording precision is improved, but fly height control stability deteriorates
Solution Approach 1:
The patent employs feedback control by continuously monitoring head-to-disk spacing and contact conditions using the sensor, and using this information to adjust fly height control parameters. This closed-loop feedback mechanism maintains fly height stability even when operating at reduced clearances for higher bit densities, resolving the contradiction between precision and stability
3Reliability
If embedded contact sensor is used to detect slider to disk contact, then contact detection is improved, but measurement precision of writer to disk spacing deteriorates
Solution Approach 1:
The patent segments the detection function into two parts: the embedded contact sensor detects contact conditions at the slider level, while a separate measurement technique (such as capacitive or inductive sensing) measures the actual writer-to-disk spacing. This segmentation allows each sensor to optimize for its specific measurement task, resolving the contradiction between contact detection reliability and spacing measurement precision
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 allows for accurate writer-to-disk contact detection and spacing sensing, enhancing the reliability of HDDs by preventing head-to-disk contact and maintaining optimal clearance, thereby improving data integrity and error rates.
Implementation Method 1
resistance of the write head device is measured to detect writer to disk spacing and contact
Implementation Method 2
This microwave oscillator produces a magnetic field in multi-Giga Hertz frequency range
Implementation Method 3
a thermal flyheight control (TFC) heater which expands the slider moving the read and write heads closer to the disk
Implementation Method 4
an embedded contact sensor (ECS), a stripe of material at an air bearing surface (ABS) of the slider changes resistance with temperature
Implementation Method 5
frictional heating from contact increases ECS temperature and resistance
Data Source
AI summary
A method, apparatus, and system are provided for implementing a write head device for writer-to-disk contact detection and spacing sensing of recording heads in hard disk drives (HDDs). A write head device, such as a spin-torque oscillator (STO), is provided between a main pole tip and a surrounding magnetic shield of the writer in the recording head. A pair of connections is provided to the magnetic shield and the main pole of the writer, and resistance of the write head device is measured to detect writer to disk spacing and contact.