Disk Drive Head Velocity Control via Torque Correction
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Solution Overview
Problem
Existing disk drive technologies face challenges in accurately controlling the head velocity on a ramp member, as conventional torque correction methods are unclear and ineffective, leading to potential head collisions with the disk.
Innovation Solution
A method is introduced to measure and calculate correction values for the torque exerted on a coil when the head is unloaded and loaded, using a ratio of travel distances to adjust torque correction values, ensuring accurate head velocity control on the ramp member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional torque correction methods are used, then head velocity control is simplified, but head velocity accuracy on the ramp member deteriorates
Solution Approach 1:
The patent performs preliminary measurements of the head's actual travel distance on the ramp member before finalizing the torque correction values. By measuring the travel distance during a test run and calculating the correction values in advance, the system ensures accurate head velocity control during actual operation without requiring complex real-time adjustments.
Solution Approach 2:
The patent implements a feedback mechanism where the head's actual travel distance on the ramp member is measured and used to calculate torque correction values. This measured feedback information is then applied to adjust the torque exerted on the coil, creating a closed-loop control system that improves head velocity accuracy based on actual performance data.
2Ease of operation
If torque correction is not applied, then device operation is simpler, but head collision risk with the disk increases
Solution Approach 1:
The patent changes the torque parameter by calculating correction values based on the head's actual travel distance on the ramp member. By adjusting the torque exerted on the coil according to measured performance data, the system prevents head collisions while maintaining relatively simple operation procedures. The parameter change is automatic and based on empirical measurements rather than complex manual adjustments.
3Reliability
If accurate head velocity control is implemented on the ramp, then head collision prevention improves, but torque measurement and correction complexity increases
Solution Approach 1:
The system performs self-measurement of the head's travel distance on the ramp member and automatically calculates the torque correction values without requiring external intervention. The disk drive itself generates the correction data by monitoring its own operation, reducing the need for complex external measurement equipment and simplifying the overall system while improving reliability.
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 allows for stable and accurate control of the head's velocity on the ramp member, reducing the risk of collisions and improving disk drive performance by properly correcting torque values.
Implementation Method 1
a torque exerted on a coil for driving the head is measured
Data Source
AI summary
In a correction value calculating method according to an embodiment, a first distance is measured as a distance actually traveled by a head while the head is unloaded. Meanwhile, a first correction value is generated. The first correction value is used to correct a first torque value exerted on a coil when the head is unloaded. Then, a second torque value is obtained with the first correction value. The second torque value is exerted on the coil when the head is actually unloaded. Based on the second torque value, a second distance traveled by the head is calculated. Then, a second correction value used to correct the second torque value is calculated based on the first correction value, and the ratio of the first distance to the second distance.