Hard Disk Drive Altitude Compensation via Flying Height Variation
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Solution Overview
Problem
Current hard disk drives face economic and logistical challenges in calibrating write parameters for varying temperatures and altitudes, as testing in simulation chambers is costly and impractical on a large scale, and reliance on altitude sensors increases drive costs.
Innovation Solution
A hard disk drive equipped with temperature and humidity sensors calculates altitude by determining variations in flying height, allowing for adjustment of write parameters without the need for an altitude sensor, using a controller to estimate and compare actual and estimated flying height variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature and altitude simulation chambers are used to calibrate write parameters, then compensation accuracy for varying environmental conditions is improved, but manufacturing cost and device complexity increase significantly
Solution Approach 1:
The patent extracts the altitude measurement function from expensive dedicated altitude sensors and simulation chambers, isolating it as a separate calculable parameter. By removing the need for physical altitude sensing hardware and chamber testing, the system achieves altitude compensation through software calculation based on available temperature and humidity data, significantly reducing manufacturing complexity while maintaining compensation accuracy
Solution Approach 2:
The patent creates a virtual model of altitude effects by calculating expected flying height variations based on temperature and humidity data. This virtual copy of altitude information is then used to adjust write parameters, replacing the need for physical chamber testing and dedicated altitude sensors, thereby reducing device complexity while preserving measurement precision
2Measurement precision
If altitude sensors are added to compensate for altitude changes, then compensation accuracy is improved, but drive cost increases
Solution Approach 1:
The patent makes existing temperature and humidity sensors perform multiple functions: their primary function remains environmental monitoring, but they also serve as the basis for calculating altitude compensation. This multi-functionality eliminates the need for separate altitude sensors, reducing manufacturing costs while maintaining compensation accuracy through the derived altitude information
Solution Approach 2:
The system uses its own existing sensor suite (temperature and humidity sensors) to generate altitude compensation data without requiring external altitude sensing hardware. The drive serves itself by calculating altitude effects from internally available environmental data, eliminating the need for additional altitude sensors and reducing overall drive cost
3Ease of manufacture
If all drives are tested at sea level and room temperature only, then manufacturing complexity is reduced, but adaptability to different environmental conditions deteriorates
Solution Approach 1:
The patent performs preliminary calculation of altitude compensation factors during manufacturing based on temperature and humidity sensor readings taken at the factory. This preliminary action creates a lookup table or calibration data that stores pre-calculated compensation values for various altitude conditions. During field operation, the drive simply retrieves and applies the appropriate compensation factors, achieving environmental adaptability without requiring complex real-time altitude sensing or re-calibration
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
Enables accurate compensation for altitude changes without additional sensors, reducing production costs and complexity, while maintaining data integrity across different environmental conditions.
Implementation Method 1
A temperature sensor of the disk drive senses a disk drive temperature
Implementation Method 2
A humidity sensor of the disk drive senses drive humidity
Implementation Method 3
The height of each air bearing is a function of the temperature, humidity and altitude within the disk drive
Data Source
AI summary
A hard disk drive that calculates an environmental condition, such as altitude, without a sensor. The disk drive includes a temperature sensor that senses a disk drive temperature and a humidity sensor that senses drive humidity. A controller of the disk drive determines whether a variation in a flying height of a head is due to a change in temperature and/or a change in humidity. If not, the controller calculates a change in altitude based on a difference between an estimated variation in flying height and the actual variation in flying height. The new calculated altitude can be used to vary disk drive operating parameters such as write parameters of the heads.