Liquid Ejecting Head With Differential Piezoelectric Displacement
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Solution Overview
Problem
Existing piezoelectric-type liquid ejecting heads, such as those in JP-A-2013-256137, while improving ejection characteristics and reducing costs by stacking thin-film piezoelectric bodies, can be further optimized by setting appropriate properties for the lower and upper piezoelectric bodies to enhance performance.
Innovation Solution
A liquid ejecting head design with a specific configuration of stacked piezoelectric elements, including a first common electrode, individual electrodes, and thin-film piezoelectric bodies, where the displacement amount of the first thin-film piezoelectric body is larger than the second during the contraction period, optimized by applying reference and drive voltages to achieve enhanced ejection characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thin-film piezoelectric bodies are stacked in layers, then displacement amount per unit voltage increases and ejection characteristics improve, but device complexity increases
Solution Approach 1:
The piezoelectric element is segmented into multiple thin-film piezoelectric bodies (first and second thin-film piezoelectric bodies) stacked in layers between common electrodes. This segmentation allows each layer to contribute to the overall displacement, achieving approximately twice the displacement per unit voltage compared to a single-layer structure, thereby improving ejection characteristics while maintaining a manageable structural complexity through systematic layering.
2Productivity
If the displacement amount of the first thin-film piezoelectric body is made larger than the second, then ejection performance improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by making the first thin-film piezoelectric body have a larger displacement amount than the second thin-film piezoelectric body during the contraction period. This non-uniform displacement distribution is intentionally designed to optimize ejection performance, with the lower piezoelectric body contributing more to the diaphragm vibration. The local quality variation is achieved through controlling the properties (such as thickness or material characteristics) of each piezoelectric layer during manufacturing.
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 optimized configuration results in improved ejection performance and displacement efficiency, allowing for better ink ejection control and reduced energy consumption.
Implementation Method 1
A piezoelectric method uses piezoelectric elements configured to cause a diaphragm constituting a part of wall surfaces of pressure compartments to vibrate. The liquid with which the pressure comparts are filled is ejected from nozzles by causing the diaphragm to vibrate by means of the piezoelectric elements.
Data Source
AI summary
wherein the pressure compartment substrate, the diaphragm, the first common electrode, the first thin-film piezoelectric body, the individual electrode, the second thin-film piezoelectric body, and the second common electrode are stacked in this order from a lower side toward an upper side, and in a contraction period, which is a period of applying the reference voltage and the drive voltage for causing the pressure compartment to contract for liquid ejection, a displacement amount of the first thin-film piezoelectric body is larger than a displacement amount of the second thin-film piezoelectric body.