Laser Guide Blocks Gaps in Head Stack Pitch Measurement

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Solution Overview

Problem

Conventional disk drive testers inaccurately determine the pitch static attitude of head stack assemblies due to gaps, leading to unnecessary adjustments or failures, as they mistake gaps for attitude issues or fail to detect future problems.

Innovation Solution

A laser-based tester with a laser guide made of stainless steel or tungsten carbide that blocks laser beams from entering gaps, reducing noise and improving measurement accuracy by only considering beams received around relevant portions of the head stack assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If conventional laser testers transmit laser beams through gaps in the head stack assembly, then the measurement process is simple, but the measurement precision deteriorates due to gaps distorting or causing errors in the determination of pitch static attitude

Engineering Contradiction:

Improvemeasurement process complexityVSAvoidpitch static attitude measurement accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent extracts and removes the harmful effect of gaps by introducing a laser guide that blocks laser beams from entering gaps in the head stack assembly. This separates the useful measurement signal from the harmful gap interference, allowing accurate measurement without the distorting influence of gaps.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The laser guide acts as an intermediary component between the laser transmitter and the head stack assembly. It mediates the laser beam path by selectively blocking beams that would enter gaps while allowing beams to pass through the intended measurement path, thus resolving the contradiction between simple measurement and accurate results.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If conventional testers do not block laser beams from gaps, then the device structure is simple, but the reliability deteriorates due to erroneous determination of pitch static attitude leading to unnecessary adjustments or replacement

Engineering Contradiction:

Improvetester structure complexityVSAvoidmeasurement reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The laser guide extracts and removes the harmful element (laser beams entering gaps) that causes erroneous measurements. By taking out this harmful interaction, the system achieves reliable measurements without the complexity of sophisticated error correction algorithms or multiple measurement systems.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the potentially harmful effect of gaps (which cause measurement errors) into a beneficial situation by using the laser guide to block gap-related beams. This transforms the problem of gaps into an opportunity to improve measurement reliability through a simple structural addition.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Measurement precision

If laser beams are blocked from entering gaps using a laser guide, then the measurement precision improves, but the device complexity increases due to additional components

Engineering Contradiction:

Improvepitch static attitude measurement accuracyVSAvoidtester structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The laser guide extracts the harmful gap interference from the measurement system in a single, simple component. This approach achieves high measurement precision without requiring complex multi-component systems or sophisticated software processing, thus minimizing the increase in device complexity.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The laser guide applies the blocking function locally at the specific location where gaps cause problems. Rather than redesigning the entire measurement system, the solution applies a localized quality change (blocking) at the critical interface between the laser beam and the head stack assembly gaps, achieving precision improvement with minimal added complexity.

Inventive Principle:

Principle #3Local quality

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

Enhances the accuracy and reliability of pitch static attitude measurements, reducing errors and improving the gage repeatability and reproducibility of data, thereby preventing unnecessary adjustments and ensuring proper head stack assembly alignment.

Implementation Method 1

a laser guide (106) to block the laser beams (128) from entering a gap (124) in the head stack assembly (108)

Methodology Applied

Scientific EffectLight blocking/absorption: Absorption (EM radiation)

Data Source

PatentUS8947651B1Tester for measuring a pitch static attitude of a head stack assembly

Publication Date: 2015.02.03 WESTERN DIGITAL TECHNOLOGIES INC

AI summary

A tester for measuring a pitch static attitude of a head stack assembly including a laser transmitter configured to transmit laser beams, and a laser receiver configured to receive the laser beams from the laser transmitter, wherein the laser transmitter and the laser receiver are configured to receive a head stack assembly between the laser transmitter and the laser receiver. The tester also includes a laser guide located between the laser transmitter and the laser receiver, and configured to block the laser beams from entering a gap in the head stack assembly and reaching the laser receiver.