Fly Height Control Using Neighboring Overlapping Tracks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing data storage devices face challenges in accurately controlling the fly height of read/write heads over disk surfaces due to interference from side-to-side head motions, making it difficult to obtain unambiguous fly height information without signal attenuation.
Innovation Solution
The method involves using neighboring overlapping data tracks, either written with a known reference signal or thermally erased/AC demagnetized, to acquire noise data and process power spectra, which are then used for precise thermal fly height control (TFC) independent of side-to-side head position variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If standard width data tracks are used for fly height measurement, then data storage density is improved, but fly height measurement precision deteriorates due to read signal attenuation from side-to-side head motion
Solution Approach 1:
The patent divides the measurement function into two separate components: (1) narrow reference data tracks specifically designed for fly height measurement, and (2) standard width data tracks for data storage. This segmentation allows the measurement function to be performed on optimized narrow tracks while maintaining high-density storage on standard tracks, resolving the contradiction between storage density and measurement precision
Solution Approach 2:
The patent introduces narrow reference data tracks as an intermediary element between the head and the main data storage system. These reference tracks serve as a dedicated measurement channel that provides clean, high-precision fly height data without interfering with the primary data storage function, acting as a mediator that separates measurement needs from storage requirements
2Extent of automation
If read signal is used to determine fly height, then fly height control is achieved, but measurement reliability deteriorates due to inability to separate side-to-side motion effects from fly height effects
Solution Approach 1:
The patent segments the disk surface into distinct functional zones: narrow reference data tracks dedicated exclusively to fly height measurement and standard width tracks for data storage. This physical segmentation ensures that measurement signals are obtained from a controlled environment where side-to-side motion effects are minimized, improving the reliability of automated fly height control
Solution Approach 2:
The patent implements a feedback mechanism where fly height measurements obtained from reading narrow reference data tracks are used to adjust thermal fly height control parameters. The separated measurement channel provides reliable feedback signals that are not contaminated by off-track motion artifacts, enabling precise automated control while maintaining measurement 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 accurate and interference-free fly height control, minimizing signal loss and maintaining stable head-disk spacing, thereby enhancing data storage precision and preventing mechanical damage.
Implementation Method 1
thermal fly height control (TFC) which employs an electrical heater (with mW powers) to heat the pole pieces of the head
Implementation Method 2
resulting in nm-level thermal expansion which pushes the pole pieces slightly closer to the spinning disk surface
Implementation Method 3
data is written to the disk medium using a write head which generates a highly localized magnetic field which aligns magnetic domains within the disk
Implementation Method 4
the head is said to 'fly' above the disk on a cushion of compressed air which is entrained by the rapid rotation of the disk
Data Source
AI summary
A data storage device and method for enabling dynamic fly height control which is insensitive to off-track motions is described. In some embodiments, a hard disk drive acquires signal data from neighboring overlapping tracks which are unwritten, thermally erased, or AC demagnetized. Side-to-side (off-track) positional errors or oscillations of the read head do not affect the signal which arises solely from the magnetic domains on the disk. Thus, signal variations may only arise from changes in the fly height. In other embodiments, neighboring overlapping data tracks are prewritten with reference data. The width of the neighboring overlapping tracks exceeds any expected side-to-side positional errors of the read head, thus signal variations may only arise from changes in the fly height. For all embodiments, the noise or reference data signal may serve as a reliable dynamic measure of the fly height with no effects arising from off-track motions.