HDD Head Actuator Shock-Responsive Repositioning

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Solution Overview

Problem

The thinning of magnetic disks in hard disk drives (HDDs) makes them prone to deformation under external shocks, causing magnetic heads to potentially contact the disks, especially at the inner circumferential side, which can lead to damage.

Innovation Solution

Incorporating a head actuator system that detects shocks and repositions the magnetic heads to a predetermined distance from the innermost circumferential portion of the disk, using a conditional formula to determine the safe retraction distance based on the disk thickness and shock value, thereby preventing contact and ensuring stable flight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the magnetic disk thickness is reduced to improve storage density, then the storage capacity increases, but the magnetic disk becomes more prone to deformation under external shocks

Engineering Contradiction:

Improvestorage capacityVSAvoiddisk resistance to deformation

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The head actuator performs preliminary repositioning of the magnetic head to a safe position before the shock can cause contact between the deformed disk and the head. The shock detection unit triggers the repositioning action as soon as shock is detected, preventing the harmful contact from occurring in the first place

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The head actuator serves as an intermediary mechanism between the shock detection unit and the magnetic head. It receives the detection signal and executes the repositioning command, acting as a mediator that translates the detection of shock into the protective action of moving the head away from the vulnerable inner circumferential region

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If the magnetic head is positioned close to the inner circumferential portion to improve data access speed, then the access speed increases, but the risk of contact with the deformed disk increases

Engineering Contradiction:

Improvedata access speedVSAvoidhead-disk contact risk

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The system dynamically adjusts the magnetic head position based on shock conditions. During normal operation, the head operates close to the inner circumferential portion for fast access. When shock is detected, the head actuator dynamically repositions the head to a safe distance, and can restore the original position after the shock passes, allowing the system to adapt its behavior to changing conditions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The head actuator applies preliminary anti-action by moving the magnetic head away from the inner circumferential portion before contact can occur. This preemptive repositioning counteracts the potential harmful effect of disk deformation, creating a safety margin that prevents contact even when the disk deforms under shock

Inventive Principle:

Principle #9Preliminary anti-action

3Reliability

If a shock detection and repositioning system is added to prevent head-disk contact, then the reliability improves, but the device complexity increases

Engineering Contradiction:

Improvehead-disk contact preventionVSAvoidsystem structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The head actuator is designed with multi-functionality, serving both as a normal positioning mechanism for data access and as a shock response mechanism for protective repositioning. The shock detection unit can be integrated with existing control circuits, allowing the system to perform multiple functions without proportionally increasing complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system implements self-service by automatically detecting shock conditions and executing repositioning actions without external intervention. The shock detection unit continuously monitors for shocks, and when detected, the head actuator automatically responds by repositioning the magnetic head, creating a self-contained protective mechanism that reduces the need for additional complex control systems

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS11114125B1Disc device with head placement responsive to shock detection

Publication Date: 2021.09.07 KK TOSHIBA

AI summary

According to one embodiment, a disk device includes a base, a discoidal recording medium including an innermost circumferential portion and an outer circumferential edge, a head, a head actuator provided pivotably on the base and supporting the head movably, a first sensor which detects a shock and a drive unit which pivots, when the shock detected by the first sensor is greater than a predetermined value and the head is located at a position less than a predetermined distance from the innermost circumferential portion, the head actuator to place the head at a position more than the predetermined distance which satisfies a conditional formula below.D=9.83⁢e-210⁢t2G