Piezoelectric Vibrator Asymmetry for Liquid Ejecting Head Displacement
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Solution Overview
Problem
Existing liquid ejecting heads with piezoelectric vibrators face issues with uneven displacement, leading to variations in ink discharge characteristics due to variations in thickness and electrode configurations, which affect the efficiency and stability of ink ejection.
Innovation Solution
A liquid ejecting head design where the piezoelectric vibrator has a laminate structure with electrodes and piezoelectric material alternately laminated, with one side having an electrode and the other side without, and the vibrator is positioned off-center to enhance displacement and reduce variations, using an island-shaped part to distribute displacement evenly across the pressure chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If external electrodes are formed on both side surfaces of the piezoelectric vibrator, then the displacement amount increases, but the thickness variation causes uneven displacement and affects ink discharge characteristics
Solution Approach 1:
The patent extracts the external electrode only from one side surface of the piezoelectric vibrator, removing it from the other side surface. This selective removal eliminates the harmful effect of thickness variation on displacement uniformity while retaining the beneficial effect of external electrodes on displacement amount from the remaining side.
Solution Approach 2:
The patent applies different electrode configurations to different regions of the piezoelectric vibrator. One side surface has external electrodes formed to maximize displacement amount, while the other side surface has no external electrodes to ensure uniform displacement. This local differentiation resolves the contradiction between displacement amount and displacement uniformity.
2Manufacturing precision
If the piezoelectric vibrator is positioned off-center with respect to the effective displacement portion, then displacement uniformity improves, but the configuration complexity increases
Solution Approach 1:
The patent employs asymmetric positioning of the piezoelectric vibrator relative to the effective displacement portion of the vibration plate. The vibrator is deliberately positioned off-center, creating an asymmetric configuration that compensates for thickness variations and achieves more uniform displacement across the vibrator surface.
3Length of moving object
If electrodes are formed on both sides of the piezoelectric vibrator, then the active displacement increases, but thickness variation causes variation in active displacement
Solution Approach 1:
The patent extracts the external electrode from one side surface of the piezoelectric vibrator, removing the source of displacement variation caused by thickness differences. This leaves only one side with external electrodes, ensuring that all piezoelectric layers experience consistent electric fields and produce uniform active displacement.
Solution Approach 2:
The patent applies external electrodes locally only to one side surface of the piezoelectric vibrator rather than both sides. This localized electrode configuration ensures consistent electric field distribution across all piezoelectric layers, eliminating variation in active displacement caused by thickness differences.
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 configuration increases the displacement amount of the piezoelectric vibrator, stabilizes ink discharge, and reduces variations in liquid amount and flying direction, enhancing the overall efficiency and stability of ink ejection.
Implementation Method 1
a piezoelectric vibrator configured to displace the vibration plate... the piezoelectric vibrator has a laminate structure in which electrodes and piezoelectric material are alternately laminated... electric fields are supplied to the piezoelectric layers so that the piezoelectric layers are deformed
Implementation Method 2
electric fields are supplied to the piezoelectric layers (active portions) sandwiched between the two internal electrodes or between the external and internal electrodes so that the piezoelectric layers are deformed. As a result, the piezoelectric vibrator expands or contracts
Implementation Method 3
The vibration plate that defines part of a pressure chamber within the flow path unit is displaced by the piezoelectric vibrator so as to change a volume of the pressure chamber, thereby causing a pressure change in the pressure chamber so that the ink is discharged through a nozzle
Data Source
AI summary
In a liquid ejecting head, a vibration plate includes an effective displacement portion provided for each pressure chamber and an island-shaped part which is provided in the effective displacement portion at a position on the opposite side to the pressure chamber and to which one end portion of a piezoelectric vibrator is bonded; the piezoelectric vibrator has a laminate structure in which electrodes and piezoelectric material are alternately laminated; a layer at an end of one side of the piezoelectric vibrator in the laminating direction is formed of an external electrode, while a layer at an end of the other side thereof in the same direction is formed of a piezoelectric material; and the piezoelectric vibrator is disposed so as to be shifted toward the other side in the laminating direction with respect to the effective displacement portion.