Storage Device Seek Control Using Timed Bias Current
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Solution Overview
Problem
Magnetic storage devices face variations in bias current values due to external forces and temperature fluctuations, leading to instability in head positioning, especially at low temperatures, which affects the accuracy of bias current calibration measured immediately after positioning.
Innovation Solution
A storage device that stores waiting time and bias current values in association with track positions, using a timer unit to apply the bias current after a waiting period to stabilize the head position, thereby reducing the impact of residual vibrations and temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If bias current is measured just after positioning process, then calibration speed is improved, but measurement precision deteriorates due to residual vibration and temperature variation
Solution Approach 1:
The patent applies preliminary action by measuring the bias current after a predetermined waiting period following the positioning process. This waiting period allows residual vibrations to subside and temperature to stabilize, ensuring accurate measurement. The control unit stores multiple bias current values measured at different timing and selects the appropriate value based on the positioning completion timing, thereby achieving both speed and precision in calibration.
2Speed
If bias current is applied immediately after positioning, then positioning speed is improved, but positioning precision deteriorates due to external force variation
Solution Approach 1:
The control unit performs preliminary measurement of the bias current after a waiting period that allows the actuator to settle from residual vibrations. By measuring at this optimal timing rather than immediately, the system ensures that the bias current value accurately reflects the external forces present during normal operation, leading to improved positioning precision while maintaining acceptable positioning speed.
Solution Approach 2:
The system incorporates feedback by measuring the bias current at multiple different timing points after positioning and storing these values. The control unit then selects the most appropriate bias current value based on feedback about when positioning actually completed. This feedback mechanism allows the system to adapt to varying conditions and achieve consistent positioning accuracy.
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 approach ensures more accurate and stable head positioning by applying the bias current at an optimal time, reducing the influence of external forces and temperature fluctuations, thus enhancing the overall performance of the magnetic storage device across varying temperatures.
Implementation Method 1
a bias current is applied to a voice coil motor for driving the actuator
Data Source
AI summary
A storage device includes a storage unit, a timer unit and a bias current applying unit. The storage unit stores, in advance, a value of a waiting time until application of a bias current to the driving unit to eliminate an external force applied to an actuator after completion of positioning, and a value of a bias current to be applied to the driving unit after the elapse of the waiting time, in association with a track position. The timer unit reads the waiting time from the storage unit and counts an elapse of the waiting time. The bias current applying unit reads the bias current value from the storage unit and applies the bias current to the driving unit after the elapse of the waiting time.