Liquid Ejecting Head With Dual-Modulus Layers for Ejection Stability
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Solution Overview
Problem
Existing piezoelectric-type liquid ejecting heads with stacked thin-film piezoelectric bodies face challenges in achieving optimal ejection characteristics and cost efficiency due to the limitations of uniform material properties in the stacked layers.
Innovation Solution
A liquid ejecting head design where the first thin-film piezoelectric body has a lower Young's modulus than the second thin-film piezoelectric body, with distinct voltage application to each, enhancing ejection characteristics and reducing deviations in high-frequency operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If thin-film piezoelectric bodies are stacked in layers with uniform properties, then displacement amount per unit voltage is increased, but ejection characteristics become suboptimal due to lack of property differentiation
Solution Approach 1:
The patent applies local quality by differentiating the Young's modulus between the lower and upper piezoelectric bodies. The lower piezoelectric body has a smaller Young's modulus to provide flexibility and reduce residual vibrations, while the upper piezoelectric body has a larger Young's modulus to provide structural support and stable ejection characteristics. This localized property differentiation resolves the contradiction between achieving high displacement and maintaining reliable ejection.
Solution Approach 2:
The patent uses composite materials by stacking two piezoelectric bodies with different Young's moduli. This composite structure combines the advantages of both materials: the softer lower layer reduces vibrations and the stiffer upper layer ensures stable ejection, thereby resolving the contradiction between speed and reliability.
2Productivity
If high-frequency drive signals are applied to achieve high productivity, then ejection speed increases, but residual vibrations increase causing deviation in ejection characteristics
Solution Approach 1:
The differentiated Young's modulus structure addresses high-frequency operation challenges by assigning the lower piezoelectric body (smaller Young's modulus) to absorb and reduce residual vibrations during high-frequency driving, while the upper piezoelectric body (larger Young's modulus) maintains stable ejection characteristics. This resolves the contradiction between productivity and reliability in high-frequency operations.
3Device complexity
If single-layer thin-film piezoelectric body is used, then device complexity is reduced, but displacement amount per unit voltage is insufficient
Solution Approach 1:
The patent uses a composite structure of two piezoelectric bodies with different Young's moduli to achieve higher displacement per unit voltage compared to a single-layer structure. The lower piezoelectric body with smaller Young's modulus contributes more to displacement, while the upper body provides support, collectively achieving superior performance without excessive complexity.
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 design improves ejection performance and print quality by optimizing the properties of the stacked piezoelectric bodies, reducing residual vibrations, and maintaining consistent ejection characteristics.
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.
Implementation Method 2
a first thin-film piezoelectric body; an individual electrode which is provided individually for each of the plurality of pressure compartments and to which a drive voltage is applied; a second thin-film piezoelectric body
Data Source
AI summary
A liquid ejecting head is disclosed that includes a pressure compartment substrate that includes pressure compartments, a diaphragm, a first common electrode to provide a reference voltage to the pressure components, first and second thin-file piezoelectric bodies, an individual electrode for each of the pressure compartments for applying a drive voltage, and a second common electrode to the pressure compartments and to which the reference voltage is applied. 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 a Young's modulus of the first thin-film piezoelectric body is less than a Young's modulus of the second thin-film piezoelectric body.