PZT Limiter for Micro Dual Stage Suspension

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Solution Overview

Problem

In disk drive suspensions, the large displacement of PZT actuators under shock conditions leads to cracking and poor mechanical and electrical performance due to the lack of rigid affixation at both ends to the load beam, causing off-track and off-height issues and electrical disruptions.

Innovation Solution

Integrally formed stainless steel PZT displacement limiters are added to constrain the vertical travel of PZTs, engaging with the load beam to prevent excessive movement and potential damage during shocks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If PZT actuators are mounted on the flexure without rigid affixation at both ends, then the suspension allows flexible movement and positioning, but the PZT actuators experience large displacement under shock conditions leading to cracking and poor mechanical/electrical performance

Engineering Contradiction:

Improveflexible movement capabilityVSAvoidPZT actuator durability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-positioning limiter structures (such as lips, flanges, or blocking features) on the flexure or load beam that will engage with the PZT actuator ends before excessive displacement occurs. These limiters are built into the structure in advance to prevent the PZT from traveling beyond safe boundaries during shock events, thereby maintaining reliability while preserving flexible movement capability.

Inventive Principle:

Principle #10Preliminary action

2Object-affected harmful factors

If PZT actuators are allowed to move freely during shock conditions, then the suspension can absorb shock energy, but the PZT actuators crack and electrical disruptions occur

Engineering Contradiction:

Improveshock energy absorptionVSAvoidPZT cracking and electrical disruption

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The patent introduces intermediary limiter structures that act as mediators between the PZT actuator and the shock load. These limiters (such as protruding lips, flanges, or blocking features positioned at predetermined distances from the PZT mounting points) absorb and distribute shock energy before it can cause the PZT to crack or generate electrical disruptions. The limiters serve as a buffer that protects the fragile PZT while still allowing controlled movement.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If the distance between welds holding flexure to load beam is large, then the flexure has greater freedom of movement, but the PZT actuators experience excessive displacement under shock

Engineering Contradiction:

Improveflexure movement freedomVSAvoidPZT displacement control

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent applies segmentation by dividing the flexure-load beam connection into functional zones: the weld regions provide rigid attachment, while the limiter structures (such as lips, flanges, or blocking features) provide controlled movement boundaries. This segmentation allows the flexure to move freely within safe boundaries while preventing excessive displacement of the PZT actuators, thus maintaining both ease of operation and manufacturing precision.

Inventive Principle:

Principle #1Segmentation

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

The PZT limiters effectively prevent cracking and maintain mechanical and electrical stability by limiting vertical displacement, ensuring precise positioning and reducing electrical disruptions during operational shocks.

Implementation Method 1

When PZT 40 expands or contracts in its longitudinal direction in response to a driving voltage, it pushes or pulls on gimbaled portion 30 to rotate that gimbaled portion and thus move read/write head 38.

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

PZT limiters can engage corresponding portions of the load beam to limit the vertical displacement of the PZTs, such as by projecting through an aperture(s) in the load beam and engaging the other side thereof

Methodology Applied

Scientific EffectMechanical constraint: Mechanical Force

Data Source

PatentUS9214176B1PZT limiter for a micro dual stage actuated suspension

Publication Date: 2015.12.15 MAGNECOMP CORP

AI summary

A PZT limiter in a microactuator type dual stage actuated (DSA) suspension limits travel of the PZT, particularly of the cantilevered end of the PZT and particularly during non-operational shock. The PZT limiter thus limits the stresses including bending placed on the PZT during the shock event and thus helps to prevent cracking of the PZT. Additionally, by limiting displacement of the PZT, the limiter improves the mechanic and electrical performance of the suspension during operation.