Disk Drive Actuator Latch with Asymmetric Magnet Biasing
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Solution Overview
Problem
Conventional actuator latches in disk drives, especially in mobile devices, are insufficient in withstanding mechanical shocks due to inadequate magnetic biasing forces, which can lead to damage of the head gimbal assemblies and adjacent disk surfaces during sudden rotational accelerations.
Innovation Solution
The design enhances the magnetic biasing force of the actuator latch by using a configuration with larger and smaller rare earth permanent magnets and a ferromagnetic biasing element, such as a steel ball, to improve the latch's ability to secure the actuator during mechanical shocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional actuator latches are used with standard magnetic biasing forces, then the disk drive can operate normally during regular use, but the latch cannot withstand mechanical shocks and sudden rotational accelerations
Solution Approach 1:
The patent changes the magnetic field parameters by using two permanent magnets with different sizes (first magnet larger than second magnet) to create an enhanced and non-uniform magnetic biasing force on the ferromagnetic ball, improving the latch's ability to withstand mechanical shocks
Solution Approach 2:
The patent employs a composite magnetic system combining two permanent magnets of different sizes with a ferromagnetic ball, creating a multi-component magnetic biasing mechanism that provides superior shock resistance compared to conventional single-magnet designs
2Reliability
If the magnetic biasing force on the latch is increased to withstand mechanical shocks, then the latch can secure the actuator during sudden rotational accelerations, but the device complexity increases
Solution Approach 1:
The patent segments the magnetic biasing function into two separate permanent magnets of different sizes, with the larger first magnet providing primary biasing force and the smaller second magnet providing additional enhancement, allowing optimized performance while maintaining modular simplicity
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 significantly increases the magnetic biasing force, enhancing the robustness of the disk drive to survive mechanical shocks and preventing damage to the head gimbal assemblies and disk surfaces.
Implementation Method 1
an actuator latch may include a ferromagnetic material (e.g. a steel ball) that is attracted to one or both voice coil motor (VCM) magnets
Implementation Method 2
The latch includes a ferromagnetic biasing element, such as a steel ball
Data Source
AI summary
A disk drive includes a disk drive base and a disk rotatably mounted to the disk drive base. First and second permanent magnets are fixed to the disk drive base. An actuator is pivotably mounted to the disk drive base. The actuator defining an actuator pivot axis about which the actuator pivots. The actuator includes an actuator coil disposed between the first and second permanent magnets. An actuator latch is disposed adjacent to the actuator. The actuator latch includes a biasing element that comprises a ferromagnetic material. An overlapping portion of the first permanent magnet overlaps the second permanent magnet as viewed from a viewing direction that is parallel to the actuator pivot axis. A protruding portion of the first permanent magnet does not overlap the second permanent magnet as viewed from the viewing direction.