Voice coil motor composite magnet assembly including low coercivity magnetic material

By using composite magnet components in HDD voice coil motors, combining low coercive and high coercive magnets, the environmental and cost problems of rare earth magnetic materials are solved, and the magnetic stability and permeability of new categories of magnetic materials are improved.

CN119724257APending Publication Date: 2025-03-28WESTERN DIGITAL TECHNOLOGIES INC
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Patent Information

Application Number
CN202410584840.0
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Priority Date
2023-09-27
Filing Date
2024-05-11
Publication Date
2025-03-28

AI Technical Summary

Technical Problem

In hard disk drives (HDDs), the prior art uses rare earth magnetic materials, which has problems of environmental problems and high costs. At the same time, the new category of low-coercive magnetic materials faces the problems of insufficient magnetic stability and magnetic permeability in applications.

Method used

By using composite magnet components in voice coil motors (VCMs), combining low coercive magnets and high coercive magnets, effectively replace the weakest areas of low coercive magnets, improving magnetic permeability and enhancing magnetic stability.

Benefits of technology

The magnetic stability and magnetic permeability of low-coercive magnetic materials in HDD VCM are achieved, reducing the use of rare earth materials, saving costs and reducing environmental impact.

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Abstract

A voice coil motor (VCM) includes: a coil; and a first yoke on the first side, the first yoke having a coil side facing the coil; a first low-coercivity permanent magnet located between the coil and a coil side of the first yoke, and having a yoke side facing the first yoke and a coil side opposite to the yoke side; and a first high-coercivity permanent magnet adjacent to the coil side of the first low-coercivity magnet. Second sides of the VCM on opposite sides of the coil are similarly configured. The magnetic conductance of such a VCM enables magnetic stability of low coercivity magnetic materials. Additional high-coercivity permanent magnets may be bonded to the coil side of each of the first and second yokes and adjoin the yoke side of each of the low-coercivity permanent magnets, if the relative thickness of the magnet material is thus determined by design.
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