Protrusion Permanent Magnet Member Voice Coil Motor Latch Stability

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Solution Overview

Problem

The increasing recording density in magnetic disks demands higher precision and stability in the control of magnetic heads during retraction from magnetic disks, which existing latch mechanisms fail to achieve effectively.

Innovation Solution

A permanent magnet member for a voice coil motor featuring a rare-earth magnet with a fan-shaped design and a protrusion, where the sum of the magnet matrix and coating thickness is greatest at the protrusion, providing enhanced magnetic attraction and stability for the latch mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional latch mechanism with a simple protrusion is used, then the structure is simple, but the control precision and stability of magnetic head retraction are insufficient

Engineering Contradiction:

Improvestability of magnetic head retraction controlVSAvoidstructure complexity of permanent magnet member

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention applies local quality by creating a protrusion with increased thickness (sum of magnet matrix and coating thickness is largest in the protrusion) at a specific location on the permanent magnet member. This localized structural enhancement concentrates magnetic flux in the protrusion region, providing stronger and more stable magnetic attraction for the latch mechanism without increasing the overall complexity of the entire permanent magnet member structure.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention changes the thickness parameter of the permanent magnet member by making the protrusion thicker than other regions. This parameter change increases the magnetic flux density in the protrusion area, thereby improving the magnetic attraction force and stability of the latch mechanism while maintaining a relatively simple overall structure.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If the magnetic head is positioned close to the magnetic disk for high precision data reading/writing, then data access precision is improved, but the risk of collision during retraction increases

Engineering Contradiction:

Improveprecision of magnetic head positioningVSAvoidcollision risk between magnetic head and magnetic disk

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The invention applies preliminary action by designing the protrusion structure that generates strong magnetic attraction force before the magnetic head completes its retraction motion. This pre-established magnetic field in the protrusion region ensures that the magnetic head is reliably attracted and held at the correct retraction position, preventing collision with the magnetic disk while maintaining high positioning precision during normal operation.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If a uniform thickness permanent magnet member is used, then manufacturing is simple, but the magnetic attraction stability for latch mechanism is insufficient

Engineering Contradiction:

Improvemagnetic attraction stabilityVSAvoidmanufacturing complexity of varying thickness structure

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

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 ensures stable control and improved stability during magnetic head retraction and operation, preventing collisions and enhancing the precision of data reading and writing processes.

Implementation Method 1

the magnetic head is retracted from above the magnetic disk by magnetic attraction to this protrusion

Methodology Applied

Scientific EffectMagnetic attraction: Magnetism

Implementation Method 2

a coating covering a surface of the magnet matrix

Methodology Applied

Scientific EffectCoating: Coatings

Data Source

PatentUS8659851B2Permanent magnet member for voice coil motor and voice coil motor

Publication Date: 2014.02.25 TDK CORP

AI summary

A magnetic head is controlled more stably when retracted from above a magnetic disk. When a permanent magnet member 10 having a protrusion projecting from the longer periphery to a side opposite to the center of a fan is mounted on a yoke 15, the end part P side where the sum of thicknesses (P1+P2) is the largest, i.e., the upper face side of a magnet matrix 111 on the protrusion side, is higher than the upper face side of the magnet matrix in the other area. Therefore, since the magnet matrix 111 in the protrusion is located closer to a lock pin 21, the magnetic attraction force between the lock pin 21 and the permanent magnet member 10 becomes stronger, so that the permanent magnet member 10 is locked more firmly when retracted from above the magnetic disk (at the time of locking), whereby the stability can be enhanced.