Magnetic Head Flying-Height Control With Microactuator Voltage Clipping
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Solution Overview
Problem
Fluctuations in the flying amount of a magnetic head occur due to sudden changes in drive voltage and external disturbances, affecting the accuracy of data writing and reading operations in magnetic disk devices.
Innovation Solution
A controller system with a voltage clipping section and an adjustment section that sets a predetermined voltage clip value based on detected fluctuations, and a protection section that stops operations when threshold values are exceeded, to stabilize the flying amount of the magnetic head.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the drive voltage to the microactuator suddenly changes to quickly adjust the magnetic head position, then the seek speed is improved, but large fluctuations occur in the flying amount of the magnetic head
Solution Approach 1:
The voltage clipping section dynamically adjusts the drive voltage to the microactuator by clipping the voltage waveform at a predetermined level. This dynamic voltage control allows the magnetic head to quickly reach the target position while preventing excessive voltage fluctuations that would cause large changes in flying amount, thus resolving the contradiction between seek speed and flying amount stability.
Solution Approach 2:
The invention changes the voltage parameter by introducing a clipping level that limits the maximum voltage amplitude. This parameter modification allows the system to maintain fast response (by allowing voltage changes up to the clip level) while preventing the large voltage excursions that would destabilize the flying amount, thereby balancing speed and stability.
2Speed
If high frequency noise is superimposed on the drive voltage to improve response time, then the microactuator response is faster, but unnecessary fluctuations in the flying amount occur
Solution Approach 1:
The invention converts the harmful effect of high frequency noise into a beneficial filtering mechanism. By clipping the voltage waveform, the system removes high frequency noise components that would cause unnecessary flying amount fluctuations, while preserving the essential voltage changes needed for microactuator response. The clipping action transforms what would be harmful noise into a controlled voltage profile.
Solution Approach 2:
The voltage clipping section acts as an intermediary between the control signal and the microactuator. It mediates the drive voltage by clipping it at a predetermined level, thereby eliminating high frequency noise components before they reach the microactuator. This intermediary function allows the system to maintain fast response while blocking the harmful high frequency fluctuations that would destabilize the flying amount.
3Manufacturing precision
If the drive voltage is increased to compensate for seek accuracy, then the positioning accuracy is improved, but the flying amount fluctuations become more severe
Solution Approach 1:
The voltage clipping section provides dynamic voltage control that allows high voltage excursions only within the clipped waveform envelope. This dynamic control enables the system to use high voltage when needed for positioning accuracy while preventing the sustained high voltage levels that would cause severe flying amount fluctuations. The clipping creates a controlled dynamic voltage profile that balances accuracy and stability.
Solution Approach 2:
The invention modifies the voltage parameter by imposing a clipping level that shapes the voltage waveform. This parameter change allows the system to achieve sufficient voltage amplitude for positioning accuracy while the clipping action prevents excessive voltage buildup that would destabilize the flying amount. The clipped waveform parameter provides both the amplitude needed for accuracy and the limitation needed for stability.
Data Source
AI summary
According to one embodiment, a magnetic disk device comprising a magnetic disk, a magnetic head, a first actuator, a second actuator, a detection section which detects a flying amount of the magnetic head to the magnetic disk, and a controller which controls drive of the first actuator and drive of the second actuator.