Magnetic Disk Unit Helium Gas Inlet Filter Design

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Solution Overview

Problem

The existing methods for recording servo data on magnetic disks face challenges due to air flow-induced shaking, which distorts tracks and hampers magnetic head positioning, and require a clean room environment for introducing low-density gases like helium to mitigate this issue.

Innovation Solution

A method involving a hermetically sealed enclosure with filtered gas inlets and outlets, where a breathing filter at the gas inlet and a less effective filter at the gas outlet allow for easy introduction of low-density gases like helium, enabling servo data writing without the need for a clean room environment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If helium is introduced into the enclosure through a gas inlet hole, then the magnetic disk experiences less shaking and forms nearly round tracks, but particles can enter the enclosure through the gas inlet hole in non-clean room environments

Engineering Contradiction:

Improvetrack roundnessVSAvoidparticle contamination

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

A filter is introduced as an intermediary component between the gas inlet hole and the enclosure interior. The filter allows helium gas to pass through while blocking particles, thus resolving the contradiction between enabling helium introduction for track quality and preventing particle contamination.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The gas inlet structure is given a special local quality by equipping it with a filter, while the rest of the enclosure remains hermetically sealed. This localized modification allows selective permeability only at the gas inlet, enabling gas exchange while maintaining overall enclosure integrity and preventing particle entry.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If the enclosure is hermetically sealed, then particle contamination is prevented, but helium gas cannot be introduced for reducing magnetic disk shaking

Engineering Contradiction:

Improveparticle contaminationVSAvoidhelium introduction capability

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The hermetic sealing is segmented by creating a localized exception at the gas inlet hole. The enclosure body remains hermetically sealed, but the gas inlet portion is divided into filter and outlet components, allowing controlled gas exchange without compromising overall seal integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The filter serves as an intermediary that reconciles the contradiction between hermetic sealing and gas introduction. It allows the enclosure to maintain its hermetic properties while enabling selective gas exchange through the filtered gas inlet.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If air is used in the enclosure, then the manufacturing process is simple, but the magnetic head positioning is obstructed due to distorted tracks from air flow shaking

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidtrack distortion

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The gas density parameter is changed from air (high density) to helium (low density). This parameter change reduces the shaking effect on the magnetic head support system, thereby reducing track distortion and improving positioning accuracy while still allowing for a relatively simple manufacturing process with filtered gas inlet.

Inventive Principle:

Principle #35Parameter changes

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 approach allows for the formation of nearly round tracks with reduced distortion, facilitating accurate magnetic head positioning and simplifying the manufacturing process by enabling helium introduction in normal environments, thus relaxing cleanliness requirements.

Implementation Method 1

helium has a lower density than air

Methodology Applied

Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Implementation Method 2

the gas inlet 11i, and the gas outlet 11e, which are provided respectively with filters attached thereto

Methodology Applied

Scientific EffectFiltration: Filter (physical)

Data Source

PatentUS7852595B2Magnetic disk unit and manufacturing method thereof

Publication Date: 2010.12.14 WESTERN DIGITAL TECHNOLOGIES INC

AI summary

Embodiments of the present invention relate to a method for manufacturing a magnetic disk unit, the method including a step of writing servo data into the magnetic disk while introducing a low-density gas having a lower density than air into the enclosure. In one embodiment, the magnetic disk unit is comprised of a magnetic disk, a magnetic head, and a voice coil motor which are accommodated in the hermetically sealed enclosure. The enclosure has a gas inlet and a gas outlet, which are provided respectively with filters attached thereto.