HSA Elevator Z-Height Adjustment via Head Feedback
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Solution Overview
Problem
Hard disk drives (HDDs) face challenges in maintaining optimal z-height between the head stack assembly and the data storage discs, leading to issues such as head resonance, modulation failures, and reduced recording capacity due to variations in disc thickness and environmental changes, which affect head fly height and pitch torque.
Innovation Solution
A data storage device with a head stack assembly that includes a load beam and a head gimbal assembly, where an elevator linearly moves the assembly along a shaft to adjust the z-height based on feedback signals, such as head heater power, reader-based feedback, or detected resonance, to ensure precise positioning and prevent lift tab contact with the ramp, thereby allowing more recording tracks near the outer diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the head stack assembly is positioned closer to the disc surface to increase recording capacity, then more outer diameter tracks can be accessed, but the risk of head resonance and modulation failures increases
Solution Approach 1:
The system employs feedback signals from the head interaction with the disc surface to dynamically adjust the elevator position. This feedback mechanism allows the system to optimize z-height in real-time, maximizing recording capacity while preventing head resonance and modulation failures by maintaining safe operating parameters.
Solution Approach 2:
The elevator mechanism dynamically adjusts the z-height of the head stack assembly based on operating conditions. This dynamic positioning allows the system to optimize head-disc spacing for maximum recording capacity while preventing harmful effects like head resonance by moving to safer z-height positions when needed.
2Manufacturing precision
If the z-height is adjusted to maintain optimal head fly height, then head-disc spacing is maintained, but additional feedback mechanisms and elevator control are required
Solution Approach 1:
The system uses feedback signals generated during normal head-disc interaction to control the elevator mechanism. This feedback-based approach enables precise maintenance of head-disc spacing without requiring complex external sensing systems, as the feedback is derived from the inherent interaction between the head and disc during operation.
Solution Approach 2:
The head stack assembly uses its own operational feedback (from head-disc interaction) to automatically adjust and maintain optimal z-height. This self-service mechanism reduces the need for additional complex control systems, as the system uses its own operating parameters to regulate its positioning.
3Device complexity
If the head is positioned at a fixed z-height, then the structure is simpler, but variations in disc thickness and environmental changes cause modulation failures
Solution Approach 1:
The system transitions from a fixed z-height structure to a dynamic elevator-based positioning system. This dynamic structure allows the head stack assembly to adapt to variations in disc thickness and environmental conditions, maintaining reliable operation without requiring complete redesign of the fundamental drive structure.
Solution Approach 2:
The system changes the z-height parameter dynamically based on detected conditions such as disc thickness variations and environmental factors. This parameter adjustment capability allows the system to maintain optimal head-disc spacing and prevent modulation failures while preserving the overall structural simplicity of the drive.
Data Source
AI summary
A data storage device (DSD) includes a base-deck, a disc above the base-deck, and a shaft extending perpendicular from the base-deck. The DSD also includes a head stack assembly (HSA) including a head gimbal assembly having a load beam and a head at a first end of the HSA. The head interacts with a surface of the disc. The HSA also includes a second end movably mounted on the shaft. The DSD additionally includes an elevator that linearly moves the HSA along the shaft to adjust a distance between the load beam and the surface of the disc in response to receiving a feedback signal associated with the interaction of the head with the surface of the disc. The feedback signal is one of a plurality of feedback signals employed by the elevator to adjust the distance between the load beam and the surface of the disc.