Servo Control System Using Identical Disk Patterns
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Solution Overview
Problem
Conventional magnetic recording disk drives require two separate master templates to create identical servo patterns on the front and back disk surfaces, doubling fabrication time and cost, and necessitate timing adjustments for accurate head positioning.
Innovation Solution
A magnetic recording disk drive with identical pre-patterned servo patterns on both surfaces using a single master template, allowing the servo control system to switch between servo signals from the front and back surfaces during track seeking, eliminating the need for timing adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If two separate master templates are used to create identical servo patterns on front and back disk surfaces, then accurate head positioning is achieved, but fabrication time and cost double
Solution Approach 1:
The patent merges the servo pattern creation process by using a single master template to generate servo patterns on both front and back disk surfaces through a stamping process. This eliminates the need for two separate templates while maintaining positioning accuracy, directly resolving the contradiction between manufacturing precision and fabrication time
Solution Approach 2:
The single master template serves multiple functions by creating servo patterns on both front and back surfaces of the disk. This multi-functional approach allows one template to replace what previously required two separate templates, reducing fabrication complexity and time while maintaining the required positioning precision
2Manufacturing precision
If two separate master templates are used to create identical servo patterns on front and back disk surfaces, then accurate head positioning is achieved, but fabrication cost doubles
Solution Approach 1:
The patent combines the template fabrication process into a single operation using one master template for both disk surfaces. This merging eliminates the cost of creating and maintaining a second template, directly addressing the contradiction between manufacturing precision and fabrication cost
Solution Approach 2:
The single master template acts as a reusable copy that can be used to generate servo patterns on multiple disks and both surfaces of each disk. This copying approach eliminates the need for expensive custom template fabrication for each surface, reducing overall manufacturing costs while maintaining precision
3Ease of manufacture
If servo patterns on back surface do not replicate head path, then single master template can be used, but timing adjustments are required for accurate positioning
Solution Approach 1:
The patent applies preliminary action by pre-adjusting the servo pattern geometry on the back surface during the stamping process. The arcuate lines are deliberately designed with different radii to compensate for the non-replicating head path, so that timing adjustments are built into the pattern itself rather than requiring complex real-time control corrections
4Measurement precision
If arcuate-shaped servo lines replicate head path on front surface, then constant sampling rate is achieved, but mirror image pattern required on back surface
Solution Approach 1:
The patent applies local quality by making the servo pattern geometry surface-specific. The front surface receives arcuate lines with one radius optimized for constant sampling rate, while the back surface receives arcuate lines with a different radius to account for the non-replicating head path. This localized differentiation allows both surfaces to achieve optimal performance with a single template
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 simplifies the servo control system, reduces fabrication costs, and maintains accurate head positioning across disk surfaces without requiring complex timing calculations, thereby enhancing operational efficiency and reducing production time.
Implementation Method 1
a magnetic recording disk drive with disks that have identical pre-patterned servo patterns on the front and back surfaces and a servo control system for positioning the read/write heads using the servo signals from the identical servo patterns
Data Source
AI summary
A magnetic recording disk drive has disks with identical pre-patterned servo patterns on their front and back surfaces and a servo control system for positioning the read/write heads using the servo signals from the identical servo patterns. The servo sectors on the two disk surfaces form identical patterns of angularly spaced arcuate-shaped lines that extend generally radially across the data tracks. The arcuate-shaped lines on one surface, the front surface, generally replicate the path of the recording head as it is moved across the data tracks by a rotary actuator, so that there is a constant sampling rate of the servo sectors on the front surface regardless of radial position of the head. However, the arcuate-shaped lines on the other surface, the back surface, do not replicate the path of the recording head so the servo sampling rate is not constant but varies with radial position of the head. The disk drive servo control system implements a method to enable track seeking from one data track to another data track, regardless of whether the initial disk surface and the destination disk surface are front or back surfaces.