Segmented Lower Electrode Layout for Reliable Piezoelectric Actuators

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing piezoelectric actuators in liquid discharge heads face issues with piezoelectric body damage and degradation due to differences in crystal states and stress concentration, leading to reduced reliability and discharge performance over time.

Innovation Solution

The piezoelectric actuator design includes a first lower electrode and multiple second lower electrodes separated from the first electrode, with the piezoelectric body positioned between them, reducing the area of inferior crystal states and minimizing stress concentration, thereby enhancing the piezoelectric body's reliability and preventing lead diffusion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional piezoelectric element structure is used with a single continuous lower electrode, then the manufacturing process is simple, but the piezoelectric body suffers from stress concentration and crystal state differences leading to damage and degradation

Engineering Contradiction:

Improvepiezoelectric body reliabilityVSAvoidlower electrode structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The lower electrode is divided into multiple separate electrodes (first lower electrode and second lower electrode) positioned at different locations beneath the piezoelectric body. This segmentation allows independent control and reduces stress concentration points, preventing crack propagation while maintaining manufacturing feasibility through standard electrode deposition processes

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the piezoelectric body are supported by different electrode configurations. The first lower electrode is positioned beneath regions prone to stress concentration, while the second lower electrode supports other critical areas. This localized electrode arrangement optimizes stress distribution and crystal state uniformity in specific high-risk zones without complicating the entire structure

Inventive Principle:

Principle #3Local quality

2Reliability

If the piezoelectric body extends to the full width of the opening, then the discharge performance is maximized, but stress concentration and crystal state differences cause damage and reduced reliability

Engineering Contradiction:

Improvepiezoelectric body durabilityVSAvoidliquid discharge performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The piezoelectric body is effectively segmented into multiple regions, each supported by different lower electrodes. This allows the piezoelectric body to maintain full width for optimal discharge performance while different sections experience reduced and distributed stress, preventing catastrophic failure and extending operational reliability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The electrode-piezoelectric body interface is optimized locally by positioning the first lower electrode beneath specific high-stress regions and the second lower electrode beneath other critical areas. This localized support maintains the piezoelectric body's full width for maximum discharge performance while preventing stress-induced damage in vulnerable zones

Inventive Principle:

Principle #3Local quality

3Reliability

If a single continuous lower electrode is used, then the manufacturing process is straightforward, but lead diffusion and degradation occur reducing long-term reliability

Engineering Contradiction:

Improveresistance to lead diffusionVSAvoidelectrode fabrication simplicity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The lower electrode is fabricated as multiple separate electrodes rather than a single continuous structure. This segmentation creates natural barriers that prevent lead diffusion across the entire electrode area, confining any potential lead migration to smaller, isolated regions. The segmented structure can be manufactured using standard multi-layer electrode deposition techniques already common in piezoelectric device fabrication

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

This design reduces the likelihood of cracks and degradation in the piezoelectric body, maintaining discharge performance and improving the overall reliability of the actuator.

Implementation Method 1

A liquid discharge head uses a piezoelectric actuator using a piezoelectric element to discharge liquid inside a pressure chamber from a nozzle

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS12558893B2Piezoelectric actuator, liquid discharge head, and liquid discharge apparatus

Publication Date: 2026.02.24 RICOH CO LTD

AI summary

A piezoelectric actuator includes: a substrate having an opening; a diaphragm: having a first face on one face of the substrate; and facing the opening; and a piezoelectric element including: a lower electrode; a piezoelectric body; and an upper electrode, and the lower electrode, the piezoelectric body, and the upper electrode being sequentially laminated on a second face opposite to the first face of the diaphragm in a lamination direction, wherein the lower electrode includes: a first lower electrode extending in a first direction; and multiple second lower electrodes: each extending in the first direction; on each of both sides of the first lower electrode in a second direction orthogonal to the first direction; and separated from the first lower electrode in the second direction, and the piezoelectric body is interior of both ends of the opening in the second direction.