Dedicated Servo Layer Position Error Tracking
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Solution Overview
Problem
Conventional servo systems in data storage devices, such as hard disk drives, face limitations in tracking accuracy due to the sampling rate, which is restricted by the number of servo wedges and disk rotation speed, leading to reduced storage capacity and interference from the data layer affecting servo performance.
Innovation Solution
A dedicated servo system with a separate servo layer providing continuous position error signals using dual-frequency servo bursts, orthogonal or differential servo patterns, and a synchronized average detector to reduce interference and improve tracking precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional servo systems with servo wedges are used, then the system structure is simple, but the tracking accuracy is limited due to sampling rate restrictions
Solution Approach 1:
The patent divides the storage medium into two distinct layers: a data layer for storing user data and a dedicated servo layer for providing servo information. This segmentation allows the servo system to operate independently from the data layer, enabling continuous servo signal detection without being constrained by data patterns, thereby improving tracking accuracy while maintaining system manageability
Solution Approach 2:
The patent transitions from a single-layer conventional servo system to a multi-layer architecture by adding a dedicated servo layer beneath the data layer. This dimensional change enables continuous servo signal availability throughout the radial extent of the disk, improving sampling rate and tracking accuracy without increasing the complexity of the data storage structure
2Measurement precision
If the number of servo wedges is increased to improve sampling rate, then tracking accuracy improves, but storage capacity decreases
Solution Approach 1:
By separating servo information into a dedicated servo layer distinct from the data layer, the patent eliminates the need to allocate data space for servo wedges. This allows continuous servo signals to be provided across all radial positions without reducing the area available for data storage, thereby improving tracking accuracy while maintaining storage capacity
Solution Approach 2:
The dedicated servo layer enables continuous servo signal detection throughout the radial extent of the disk, providing uninterrupted position information to the read/write head. This continuous feedback improves tracking accuracy without requiring discrete servo wedges that would consume data storage space
3Quantity of substance
If data layer is present above servo layer, then storage capacity increases, but interference from data layer degrades servo performance
Solution Approach 1:
The patent extracts the servo information from the data layer and places it in a dedicated servo layer. This separation removes the harmful interference from the data layer, as servo signals are now read from a distinct magnetic layer where data patterns do not exist, eliminating cross-talk and improving servo performance while maintaining storage capacity in the data layer
Solution Approach 2:
The dedicated servo layer acts as an intermediary between the read/write head and the data layer. By providing servo information from this intermediate layer, the system obtains accurate position feedback without the interference that would occur if servo signals were embedded in or read through the data layer
Data Source
AI summary
A system for tracking a position error of a read/write head. The read/write head is configured to read data recorded to a data layer of a recording medium and read servo information recorded to a dedicated servo layer of the recording medium. To read the servo information, the read/write head is configured to read, from a first track, a first servo signal including first servo bursts of a predetermined frequency, and read, from a second track adjacent to the first track, a second servo signal including second servo bursts of the predetermined frequency. The first servo bursts are orthogonal to the second servo bursts. A position error signal determination circuit is configured to determine the position error using at least one of the first servo signal and the second servo signal.