Fly Height Compensation via Read Gain Control Loop
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Solution Overview
Problem
Maintaining the fly height of a read/write head in data storage devices within an acceptable range becomes increasingly difficult as data storage density increases, leading to potential read/write bit errors and contact with the data storage surface, due to variations in air density and head temperature.
Innovation Solution
A circuit detects disk height variations using a variable gain amplifier within an automatic gain control loop, regulating the head fly height by adjusting a heater element to compensate for disk surface warping, thereby maintaining optimal fly height and reducing bit error rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If fly height is reduced to increase data storage density, then data storage density is improved, but fly height stability deteriorates due to air density changes and head temperature variations
Solution Approach 1:
The patent implements a feedback control system that continuously monitors fly height variations and adjusts the heater element activation accordingly. The circuit detects changes in fly height and modulates the heater element to compensate for these variations, maintaining stable fly height while enabling high data storage density operations.
Solution Approach 2:
The patent changes the temperature parameter of the head by activating a heater element to compensate for fly height variations. By controlling the temperature of the head, the system maintains consistent fly height despite changes in air density and operational conditions, thereby preserving both high storage density and flight stability.
2Stability of the object's composition
If heater element is activated to compensate for fly height variations, then fly height stability is improved, but head temperature increases
Solution Approach 1:
The patent employs periodic or pulsed activation of the heater element rather than continuous operation. The heater is activated only when and where fly height compensation is needed, based on real-time detection of fly height variations. This periodic action provides necessary temperature control for fly height stability while minimizing overall head temperature increase and associated thermal effects.
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
The solution effectively compensates for disk surface warping, maintaining a stable fly height and improving signal-to-noise ratio, thereby enhancing data storage density and preventing data loss or damage.
Implementation Method 1
Some disk drives use a heater to controllably heat the head in order to vary the fly height of the head
Implementation Method 2
a variable gain amplifier within an automatic gain control loop is used to amplify a read signal as a head reads from a surface of a disk
Implementation Method 3
The heads can be radially positioned over the disks by a rotary actuator and a closed loop servo system, and can fly in close proximity to the surfaces of the disks upon air bearings
Data Source
AI summary
Apparatus and methods are disclosed that regulate head fly height so as to compensate for variation in height of a disk surface. An exemplary apparatus includes a circuit that detects disk height variation in response to variation in the gain of a variable gain amplifier, within an automatic gain control loop, that amplifies a read signal as the head reads from the disk surface. The circuit regulates the head fly height so as to compensate for the detected variation in disk height.