Fly Height Control via Head Heater Resistance Feedback
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Solution Overview
Problem
Maintaining the flying height of read/write heads in disk drives within an acceptable range becomes increasingly difficult as data storage density increases, leading to potential read/write errors and damage due to manufacturing tolerances and temperature variations.
Innovation Solution
A fly height controller measures the electrical resistance of a heater element attached to the read/write head to control its temperature, adjusting the flying height by generating fly height adjustment signals to maintain optimal spacing between the head and disk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If data storage density is increased by narrowing tracks and flying height gaps, then data density improves, but manufacturing precision requirements worsen
Solution Approach 1:
The patent implements a feedback control system that continuously monitors head temperature (via resistance measurement) and adjusts heater power accordingly to maintain constant flying height. This closed-loop feedback mechanism compensates for temperature variations and manufacturing tolerances, enabling precise flying height control despite narrowed gaps required for high data density storage.
Solution Approach 2:
The patent dynamically changes the heater power parameter based on measured resistance values to maintain optimal flying height. By adjusting the heating parameter in response to temperature variations, the system compensates for thermal expansion and contraction of the head, ensuring consistent flying height control as data storage density increases and gaps are narrowed.
2Temperature
If head temperature varies, then flying height changes, but reliability deteriorates
Solution Approach 1:
The system uses feedback control by continuously measuring heater resistance (which correlates with head temperature) and adjusting heater power to maintain stable temperature and flying height. This feedback mechanism prevents temperature-induced flying height variations that would cause read/write errors, thereby maintaining reliability despite temperature fluctuations during operation.
Solution Approach 2:
The heater element serves dual functions: it heats the head to control flying height and simultaneously acts as a temperature sensor through its resistance measurements. This self-service capability allows the system to monitor and control its own temperature without external sensors, enabling real-time compensation for thermal effects that would otherwise compromise read/write reliability.
3Measurement precision
If heater resistance variation with temperature is non-zero, then temperature sensing is enabled, but manufacturing ease improves
Solution Approach 1:
The heater element is designed to perform multiple functions: it provides thermal control by heating the head and simultaneously serves as a temperature sensor through its resistance measurements. This multi-functionality eliminates the need for separate temperature sensors and complex manufacturing processes, simplifying production while enabling accurate temperature sensing for flying height control.
Solution Approach 2:
The heater element monitors its own temperature state through resistance measurements and uses this information to regulate its own heating output. This self-service approach enables temperature sensing without requiring external sensors or complex manufacturing, allowing the same component to both heat and sense temperature for reliable flying height control.
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 solution effectively maintains the flying height of read/write heads within a controlled range, reducing errors and preventing damage by accurately sensing temperature-induced variations and adjusting the head's position, thereby enhancing data storage density and reliability.
Implementation Method 1
a circuit includes a fly height controller that measures electrical resistance of a heater element as an indication of temperature of a read/write head
Implementation Method 2
Some disk drives controllably heat the head using a heater to vary the flying height of the head
Data Source
AI summary
A fly height controller measures electrical resistance of a heater element attached to a read/write head as an indication of head temperature and associated flying height relative to a data storage disk, and responds to the measured resistance of the heater element by varying a fly height adjustment signal applied to the heater element to change the temperature of the head and its resulting flying height.