Piezoelectric Element With Biased Internal Field For Liquid Ejection
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Solution Overview
Problem
Current piezoelectric elements in liquid-ejecting heads, such as ink-jet recording heads, face challenges in achieving large displacement at adequate or low voltage, limiting their displacement characteristics and liquid ejection efficiency.
Innovation Solution
A liquid-ejecting head design featuring a piezoelectric element with a biased internal electric field or residual dielectric polarization moment, where no voltage is applied to one electrode, allowing for enhanced displacement characteristics at low driving voltage by adjusting the composition ratio, lattice constant, and presence of an oxygen deficient sublayer in the piezoelectric layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional piezoelectric element with uniform piezoelectric material layer is used, then the structure is simple and easy to manufacture, but the displacement amount is small at adequate or low voltage
Solution Approach 1:
The piezoelectric layer is designed with non-uniform composition ratio distribution, where the ratio of piezoelectric material to other materials varies through the thickness direction. This creates local variations in piezoelectric properties, with regions of higher piezoelectric coefficient contributing more to displacement, thereby achieving larger overall displacement at lower driving voltages while maintaining manufacturing simplicity
Solution Approach 2:
The invention changes the composition ratio parameter of the piezoelectric material layer through its thickness, creating a gradient structure. By optimizing the composition ratio distribution (e.g., higher piezoelectric material concentration near the electrode), the piezoelectric coefficient is enhanced in critical regions, enabling larger displacement output at reduced driving voltages
2Force
If the piezoelectric material layer is made thicker to increase displacement, then the displacement amount increases, but the manufacturing precision and uniformity of the piezoelectric properties decrease
Solution Approach 1:
Instead of requiring uniform high-quality material throughout a thick layer, the invention concentrates the piezoelectric material in specific regions (local quality enhancement) within the layer. This allows the overall layer to remain thick for large displacement while only critical regions require high precision, reducing overall manufacturing difficulty and improving uniformity of functional properties
Solution Approach 2:
The composition ratio is varied through the thickness direction to optimize the balance between displacement generation and manufacturing precision. By creating a gradient where piezoelectric material concentration changes systematically, the invention achieves both sufficient displacement from thick layers and improved uniformity in the functional regions
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 enables improved displacement characteristics and liquid ejection performance by achieving large displacement at low driving voltage, effectively addressing the limitations of existing technologies.
Implementation Method 1
a piezoelectric element which has a first electrode, a piezoelectric layer arranged over the first electrode, and a second electrode arranged over the piezoelectric layer
Implementation Method 2
The residual dielectric polarization moment in the piezoelectric layer is biased toward the first electrode or the second electrode
Data Source
AI summary
A liquid-ejecting head including a pressure-generating chamber communicating with an nozzle, and a piezoelectric element having a first electrode, a piezoelectric layer arranged above the first electrode, and a second electrode arranged above the piezoelectric layer. An internal electric field in the piezoelectric layer is biased toward the first electrode or the second electrode and no voltage is applied to the first electrode or the second electrode.