Servo Zone Sync Mark Detection for Disk Format Efficiency
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Solution Overview
Problem
Existing data storage devices face inefficiencies in format design due to varying data rates across servo sectors, which complicate head positioning and data track access, leading to increased complexity and reduced format efficiency.
Innovation Solution
The implementation of servo zones with unique sync marks and varying data rates within each zone, where partial track addresses are recorded in servo sectors, allowing for reduced sector size and improved format efficiency by determining the current servo zone based on detected sync marks and data rates, and generating full track addresses from detected servo and partial addresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If data tracks are banded into physical zones with varying data rates to maintain constant linear bit density, then linear bit density uniformity is improved, but servo sector complexity increases due to varying data rates across zones
Solution Approach 1:
The disk surface is segmented into multiple servo zones, with each zone containing servo sectors that operate at a constant data rate. This segmentation allows the system to maintain constant linear bit density across the entire disk radius while simplifying servo sector design within each zone, as the head remains in a zone with uniform linear velocity characteristics.
Solution Approach 2:
Each servo zone is assigned a specific data rate appropriate for its radial position on the disk, creating local uniformity in data rate and linear bit density. The head transitions between zones with different local characteristics, but within each zone, the data rate is constant, simplifying servo control and sector design.
2Loss of information
If full track addresses are recorded in every servo sector, then head positioning information completeness is improved, but servo sector size increases reducing format efficiency
Solution Approach 1:
The track address information is extracted from each servo sector and used to identify the current servo zone. Once the zone is identified, only the portion of the track address relevant to that zone (partial track address) is needed for precise head positioning. This extraction approach maintains complete positioning information while reducing the data storage requirements in each servo sector.
Solution Approach 2:
The track addressing system is divided into two dimensions: zone identification (high-order bits of track address) and intra-zone positioning (low-order bits of track address). The servo zone detection provides the high-order information, and the partial track address within the zone provides the low-order information, together forming the complete track address without requiring full addresses in every sector.
3Productivity
If servo sector size is reduced to improve format efficiency, then data storage density is improved, but head positioning accuracy may deteriorate
Solution Approach 1:
The system performs preliminary zone identification by detecting the sync mark in each servo sector, which identifies the servo zone. This preliminary action allows the servo control system to know which zone the head is in before processing the partial track address, enabling accurate position calculation even with reduced sector size. The zone detection prepares the system with contextual information needed for precise positioning.
Solution Approach 2:
The sync mark serves as an intermediary element that provides zone identification information. By detecting the sync mark pattern, the system can determine the servo zone without requiring the full track address to be stored in the sector. This intermediary mechanism enables accurate head positioning while allowing for compact servo sector design.
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 enhances format efficiency by reducing the size of each servo sector, improving head positioning accuracy, and maintaining constant linear bit density across the disk, thereby simplifying design considerations and increasing data storage device performance.
Implementation Method 1
a head connected to a distal end of an actuator arm which is rotated about a pivot by a voice coil motor (VCM) to position the head radially over the disk
Implementation Method 2
The servo sectors comprise head positioning information (e.g., a track address) which is read by the head and processed by a servo control system
Data Source
AI summary
A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of servo sectors defining a plurality of servo tracks. The servo tracks form a plurality of servo zones, and at least one servo sector of a servo track comprises a partial track address. A read signal generated by the head is processed to detect a current servo zone for the head, and the read signal is processed to detect the partial track address in one of the servo sectors of the current servo zone. A full track address is generated based on the detected servo zone and the detected partial track address.