Piezoelectric Element Domain Control for Ink Jet Head
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Solution Overview
Problem
Conventional piezoelectric elements for ink jet heads face challenges in achieving high piezoelectric characteristics and durability, especially when miniaturized, due to limitations in film thickness and crystal orientation control, which affect displacement controllability and ink discharge performance.
Innovation Solution
A piezoelectric element with a tetragonal crystal film having a dominant A-domain volume proportion greater than 50 vol%, utilizing a substrate with a higher linear thermal expansion coefficient than the film, and a 90° domain structure to enhance bending mode performance and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a PZT type oxide film is used with conventional sintering method, then the piezoelectric film can be formed, but the film thickness cannot be reduced to 10 μm or less and the film shrinks about 70% when heated causing misalignment
Solution Approach 1:
The patent changes the sintering temperature parameter from conventional high temperature (1000°C or higher) to low temperature (900°C or lower), which enables formation of piezoelectric films with thickness of 10 μm or less while reducing thermal shrinkage to maintain dimensional alignment precision of several micrometers
Solution Approach 2:
The patent uses a composite piezoelectric material system comprising PbO-ZrO2-TiO2 with specific compositional ratios (ZrO2: 30-70 wt%, TiO2: 5-30 wt%, PbO: 5-30 wt%) that enables low-temperature sintering while maintaining piezoelectric properties and reducing thermal shrinkage
2Measurement precision
If the piezoelectric element is miniaturized for higher resolution printing, then the printing performance is improved, but the piezoelectric element loses driving ability due to insufficient piezoelectric constant
Solution Approach 1:
The patent optimizes compositional parameters (ZrO2 content: 30-70 wt%, TiO2 content: 5-30 wt%, PbO content: 5-30 wt%) to achieve high piezoelectric constant in miniaturized elements, and controls film thickness parameter to enhance piezoelectric effect while maintaining driving ability in miniaturized structures
Solution Approach 2:
The patent creates specific domain structures (A-domains and B-domains with different orientations) within the piezoelectric film to enhance local piezoelectric properties and maintain high driving ability even when the overall element size is reduced
3Reliability
If the piezoelectric film is sintered at high temperature (1000°C or higher), then the piezoelectric material is formed, but the film shrinks about 70% causing misalignment with structural members
Solution Approach 1:
The patent changes the sintering temperature parameter from conventional high temperature (1000°C or higher) to low temperature (900°C or lower), which maintains piezoelectric material formation while reducing thermal shrinkage to below 10%, thereby preserving dimensional stability and alignment with structural members
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 solution provides a piezoelectric element with improved displacement controllability, durability, and ink discharge stability, enabling higher resolution and faster printing in miniaturized ink jet heads.
Implementation Method 1
The piezoelectric element is an element capable of converting an electric energy into a mechanical energy such as mechanical displacement, stress or vibration
Implementation Method 2
utilizing a substrate with a higher linear thermal expansion coefficient than the film
Data Source
AI summary
A piezoelectric element includes a piezoelectric film disposed on a substrate and a pair of electrodes disposed in contact with the piezoelectric film and utilizing a bending mode. The piezoelectric film includes domains constituted of a tetragonal crystal and including an a-domain which is formed by a crystal having a (100) plane parallel to the film surface of the piezoelectric film, the a-domains include an A-domain having a normal axis of (001) plane substantially parallel to a principal bending direction of the piezoelectric film and a B-domain having a normal axis of (001) plane substantially perpendicular to the principal bending direction of the piezoelectric film, and the A-domains have a volume proportion larger than 50 vol % with respect to the sum of the volume of the A-domains and the volume of the B-domains.