HDD Disk Stack Rigidity and Spacer Thermal Expansion
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Solution Overview
Problem
As disk devices, such as hard disk drives (HDDs), become thinner, they are more susceptible to impact-induced deflection, leading to potential contact between magnetic heads and disks, which can cause mechanical issues and data loss.
Innovation Solution
The use of a housing design with magnetic recording media stacked coaxially and separated by spacer rings, where the uppermost and lowermost disks have substrates with higher rigidity than the intermediate disks, and spacer rings with thermal expansion coefficients different from the others, to reduce impact-induced vibration and eccentricity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of magnetic disks is increased and the magnetic disks are made thinner to achieve high capacity, then the storage capacity is improved, but the amount of deflection of the magnetic disks increases when the device is subjected to impact
Solution Approach 1:
The patent applies local quality by making the uppermost and lowermost magnetic disks have different properties (higher rigidity) compared to the intermediate magnetic disks. This localized differentiation allows the end disks to provide enhanced impact resistance while the intermediate disks maintain thinness for high capacity, resolving the contradiction between storage density and impact resistance.
Solution Approach 2:
The patent uses composite materials by combining magnetic disks with different rigidity characteristics in a single assembly. The uppermost and lowermost disks use materials or structures with higher rigidity, while intermediate disks use thinner materials, creating a composite structure that optimizes both capacity and impact resistance.
2Quantity of substance
If the magnetic disks are made thinner to increase capacity, then the storage density is improved, but the magnetic disks become more susceptible to deflection and contact with magnetic heads or ramps
Solution Approach 1:
The patent implements local quality by providing enhanced rigidity specifically at the uppermost and lowermost magnetic disks, which are most vulnerable to impact-induced deflection. This localized reinforcement prevents contact between magnetic heads/ramps and disks while maintaining thin intermediate disks for high storage density.
Solution Approach 2:
The patent applies beforehand cushioning by positioning the higher rigidity magnetic disks at the outermost positions to act as protective elements that absorb and distribute impact forces before they can reach the thinner intermediate disks, preventing mechanical contact and potential damage.
3Stability of the object's composition
If spacer rings with different thermal expansion coefficients are used for the uppermost and lowermost magnetic disks, then the eccentricity caused by thermal expansion is reduced, but the device complexity increases
Solution Approach 1:
The patent applies local quality by assigning different thermal expansion coefficient properties specifically to the spacer rings associated with the uppermost and lowermost magnetic disks, rather than using uniform spacer rings throughout. This localized differentiation compensates for thermal expansion effects and reduces eccentricity while maintaining relatively simple overall structure.
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 configuration enhances the impact resistance of HDDs by minimizing vibration and eccentricity, allowing them to withstand greater shock without data loss or mechanical failure.
Implementation Method 1
spacer rings brought into contact with the magnetic recording media with the substrate having the higher rigidity have a thermal expansion coefficient different from a thermal expansion coefficient of the other spacer rings
Data Source
AI summary
According to one embodiment, a disk device includes a housing, a plurality of magnetic recording media disposed in the housing in a multi-layered manner with intervals therebetween and a plurality of spacer rings, one of the spacer rings being disposed between each adjacent pair of the magnetic recording media. At least one of an uppermost magnetic recording medium and a lowermost magnetic recording medium includes a substrate having a rigidity higher than that of substrates of the other magnetic recording media, and one or more of the plurality of spacer rings is in contact with the magnetic recording media including the substrate having the higher rigidity, and has a thermal expansion coefficient different from a thermal expansion coefficient of the other spacer rings.