Piezoelectric Microactuator Head-Disc Contact Detection

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Solution Overview

Problem

Head merge stations in disc drive assembly lines can go out of calibration, leading to head-disc contact during the manufacturing process, causing damage to both the heads and discs, which reduces the reliability of disc drives and results in customer returns and self-test failures due to the difficulty in detecting calibration issues in real-time.

Innovation Solution

A method involving a circuit connected to head positioning microactuators, specifically piezoelectric microactuators, which generate electrical signals upon deflection, allowing for the detection of head-disc contact through a signal path and contact detection circuit, triggering maintenance before further assembly to prevent additional damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If head merge station operates without continuous monitoring, then assembly process continues uninterrupted, but head-disc contact damage occurs due to calibration drift

Engineering Contradiction:

Improveassembly throughputVSAvoidhead-disc contact prevention

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements a feedback mechanism by monitoring the output signal from the head positioning microactuator in real-time during the head merge operation. The contact detection circuit continuously evaluates this signal to detect head-disc contact events, providing immediate feedback that allows the system to stop and prevent further damage while maintaining assembly productivity.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces mechanical calibration verification methods with an electrical signal-based detection system. By using the microactuator's output signal and contact detection circuitry, the system electronically monitors head positioning and detects contact events without requiring mechanical intervention or disruption to the assembly process.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If head positioning is monitored using traditional methods, then calibration issues are detected late, but implementation complexity increases with advanced sensing systems

Engineering Contradiction:

Improvehead-disc contact detection accuracyVSAvoiddetection system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies the self-service principle by utilizing the existing microactuator's output signal for contact detection purposes. The same microactuator that positions the head also provides the signal used to detect contact, eliminating the need for separate sensing systems and reducing overall device complexity while maintaining high measurement precision.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent implements multi-functionality by using the microactuator's output signal for both head positioning control and head-disc contact detection. This universal approach allows a single component to serve multiple functions, reducing system complexity while achieving accurate contact detection.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Speed

If head merge operation proceeds without real-time detection, then assembly speed is maintained, but damage to heads and discs occurs

Engineering Contradiction:

Improvehead merge operation speedVSAvoidhead-disc contact damage

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent enables the head merge operation to proceed rapidly through the critical positioning phase by using real-time signal monitoring to detect contact events instantaneously. The system can rush through the positioning operation at high speed while the contact detection circuit provides continuous monitoring, allowing immediate detection and stopping upon contact to prevent damage.

Inventive Principle:

Principle #21Skipping (Rushing through)

Solution Approach 2:

The patent implements preliminary action by continuously monitoring the microactuator output signal before actual head-disc contact damage occurs. The contact detection circuit evaluates the signal in advance to predict and detect potential contact events, allowing the system to take preventive action before significant damage can occur to the heads or discs.

Inventive Principle:

Principle #10Preliminary action

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

Reliably detects head-disc contact, enabling timely maintenance and preventing damage to disc drives, thereby enhancing the reliability and reducing customer returns and self-test failures by ensuring accurate head positioning during the assembly process.

Implementation Method 1

Piezoelectric head positioning microactuators commonly used in disc drives produce an electrical signal in response to a deflection caused by head-disc contact.

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS7502194B2Head-disc contact detection using a microactuator

Publication Date: 2009.03.10 SEAGATE TECH LLC

AI summary

A method for detecting head-disc contact in a disc drive is disclosed. The method comprises monitoring an output signal from a head positioning microactuator on a read/write head in the disc drive and evaluating the output signal to determine if the read/write head contacts a disc of the disc drive.