Conductive Capsule Meniscus for Electrostatic Discharge in Disk Drives
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Solution Overview
Problem
In disk drive storage systems, electrostatic discharge due to triboelectric charge build-up is a concern, especially with gas-based fluid dynamic bearings, where charge transfer is blocked, leading to potential damage from electrostatic discharge between the thin film head and disc surface, and existing ferrofluidic seals contaminate and degrade reliability.
Innovation Solution
An electrostatic discharge apparatus featuring a conductive capsule with capillary channels filled with a conductive fluid, allowing a meniscus to contact the spindle during rotation, providing a conductive path to prevent charge buildup without the contamination risks of ferrofluidic seals, using a non-metallic, non-magnetic additive to enhance conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gas-based fluid dynamic bearings are used to reduce friction and rotational drag, then productivity and speed are improved, but electrostatic charge transfer is blocked leading to electrostatic discharge damage
Solution Approach 1:
A conductive capsule is introduced as an intermediary component between the hub and spindle. This capsule contains a conductive fluid that forms a conductive path, allowing electrostatic charge to transfer from the hub to the spindle through the gas-filled bearing assembly, thus preventing electrostatic discharge damage while maintaining the benefits of gas-based fluid dynamic bearings.
2Object-affected harmful factors
If ferrofluidic seals are used to provide conductive path, then electrostatic charge transfer is enabled, but contamination occurs degrading reliability
Solution Approach 1:
The invention changes the physical state and composition parameters of the sealing medium. Instead of using ferrofluid (liquid state with magnetic particles), the patent employs a conductive fluid with different properties that does not outgas or contaminate. The conductive capsule is filled with this alternative conductive fluid that maintains electrical conductivity while eliminating the contamination issue associated with ferrofluidic seals.
3Object-affected harmful factors
If conductive fluid is used in capillary channels, then electrostatic discharge is prevented, but device complexity increases
Solution Approach 1:
The conductive capsule is constructed as a flexible or rigid shell structure that can be integrated into the existing bearing assembly. The capsule contains capillary channels that wick the conductive fluid from a reservoir to the contact interface between hub and spindle. This thin-film or shell-based approach provides the necessary conductive path without requiring complex mechanical structures, thus minimizing the increase in device complexity.
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
Effectively prevents electrostatic charge buildup between the thin film head and disc surface, maintaining long operational life and reliability while avoiding contamination and magnetic field issues, with improved conductivity and lubrication performance.
Implementation Method 1
defining at least one capillary channel in fluid communication with a first opening formed in the capsule, the first opening configured to permit rotation about the spindle, and to permit a meniscus formed by the conductive fluid proximate to the opening to electrically contact the spindle during rotation of the hub about the spindle
Implementation Method 2
providing a conductive path to prevent charge buildup
Data Source
AI summary
An electrostatic discharge apparatus for use with a hub and spindle assembly for a disc drive storage system comprising a spindle; a hub rotatably mounted on the spindle; a capsule formed at least in part from an electrically conductive material that can be placed in electrical communication with the hub and defining a chamber configured to hold an electrically conductive fluid and defining at least one capillary channel in fluid communication with an opening formed in the capsule, the opening configured to permit rotation about the spindle, and to permit a meniscus formed by the conductive fluid proximate to the opening to electrically contact the spindle during rotation of the hub about the spindle.