Trapezoidal Bridge ABS for Uniform Dynamic Flying Height
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Solution Overview
Problem
Existing dynamic flying height (DFH) slider technologies face challenges in achieving uniform and stable aerodynamics, minimal flying height variations, and efficient power usage across a wide range of conditions, including temperature and altitude changes, due to issues like high pressure on heated areas, disk distortions, and non-uniform DFH efficiency across the disk radius.
Innovation Solution
A new air bearing surface (ABS) design featuring a micro-pad with embedded read/write head and heating elements, partially surrounded by a centrally symmetric structure with projecting wings and a bridged connection, which maintains stable air pressure and uniform DFH efficiency across the disk surface through a rectangular or trapezoidal bridge shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If heating coils are embedded in the slider to heat the region around the read/write head, then the read/write head can approach the disk surface more closely (reduced flying height), but the flying height control becomes unstable and non-uniform across the disk surface
Solution Approach 1:
The air bearing surface is divided into multiple functional zones including a heated zone, a bridge zone, and a non-heated zone. This segmentation allows different regions to perform different functions: the heated zone creates thermal protrusion for head positioning, while the bridge zone provides aerodynamic support to stabilize the flying height and reduce variations across the disk surface.
Solution Approach 2:
Different regions of the air bearing surface are given different thermal and aerodynamic properties. The heated region has high thermal conductivity to enable protrusion, while the bridge region is designed with specific aerodynamic characteristics to provide stable support. This local differentiation allows simultaneous achievement of head positioning and flying height stability.
2Length of moving object
If the slider is heated to reduce flying height, then the read/write head can be positioned closer to the disk, but power consumption increases and aerodynamic stability deteriorates
Solution Approach 1:
Instead of heating the entire slider, only a specific localized region is heated to create the necessary thermal protrusion. The bridge zone and other regions remain cooler, reducing overall power consumption while still achieving the required flying height reduction at the read/write head position.
Solution Approach 2:
The bridge zone acts as an intermediary structure between the heated zone and the non-heated zone. It provides aerodynamic support that mediates the conflict between thermal protrusion (which reduces flying height) and aerodynamic stability (which requires broader support), allowing efficient power usage while maintaining stability.
3Ease of manufacture
If the air bearing surface is made planar, then manufacturing is simpler, but aerodynamic performance and flying height uniformity across the disk radius are compromised
Solution Approach 1:
The air bearing surface features localized topographical variations including raised pads, grooves, and bridge structures at specific positions, while maintaining overall planarity. These local features are strategically placed to enhance aerodynamic performance and ensure uniform flying height across the disk radius without requiring complex overall surface geometry.
Solution Approach 2:
The air bearing surface is segmented into distinct functional regions with different topographical characteristics. These segments include heated zones, bridge zones, and airflow channels, each designed to perform specific aerodynamic functions that collectively ensure stable and uniform flying height across the entire disk surface.
4Productivity
If the slider design is optimized for inner radius of the disk, then DFH efficiency is improved at ID, but flying height variations increase at outer radius and middle diameter
Solution Approach 1:
The air bearing surface design incorporates features that serve multiple functions and perform effectively across different disk radii. The bridge zone and segmented structure provide aerodynamic support that is beneficial at inner radius, middle diameter, and outer radius, making the design universal and effective across the entire disk surface rather than optimized for a single location.
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 new ABS design achieves uniform DFH efficiency and reduced sensitivity to disk radius variations, ensuring stable flying height and reduced power consumption, while minimizing the risk of flying height modulations and improving the reliability of disk drives.
Implementation Method 1
The purpose of these coils is to heat the slider in the region around the read/write head and cause a thermal protrusion of the slider in that region so that the read/write head can be made to approach the surface of the disk more closely
Implementation Method 2
The slider is a ceramic structure with a smooth, planar surface (300), called its ABS (air bearing surface) that is supported over a rapidly spinning disk by aerodynamic forces produced a flow of air between the slider and the disk
Data Source
AI summary
A DFH (Dynamic Flying Height) type slider ABS design has a stable flying height and a DFH efficiency that is uniform across the entire disk surface. These properties are a result of embedding the read/write head and heater in a trapezoidally bridged micro-pad having a very small surface area. The micro-pad is surrounded by a wing-like structure that projects from a central rail in the ABS and the micro pad is connected to an inner edge of that structure by a bridge having a trapezoidal shape. The trapezoidal shape responds effectively to variations in air flow direction and pressure point as the slider moves across the disk surface and, as a result, provides the uniform DFH efficiency. At the same time, the projecting wings and adjacent topology help to direct the airflow around the micro-pad and provide the stable flying height.