Piezoelectric Inkjet Actuator Electrode Extension
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Solution Overview
Problem
The existing ink-jet head piezoelectric actuators have limited deformation in the central portion of pressure chambers, leading to reduced drive efficiency and durability due to constrained deformation near the inner circumference, which affects the ability to apply substantial pressure with low drive voltage.
Innovation Solution
The piezoelectric actuator design includes individual electrodes extending to the edge and outside of pressure chambers, allowing increased deformation of the vibration plate, particularly at the edge and outside areas, to enhance pressure chamber volume change and reduce polarization deterioration by applying the electric field only during ink discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If individual electrodes are formed only in areas overlapping the pressure chambers, then the structure is simple and manufacturing is easy, but the piezoelectric layer deformation is constrained near the inner circumference, reducing drive efficiency
Solution Approach 1:
The individual electrodes are extended from the two-dimensional area within the pressure chamber boundary into the third spatial dimension by protruding beyond the pressure chamber circumference. This dimensional extension allows the piezoelectric layer to deform in previously constrained areas, increasing the effective deformation area and improving drive efficiency without complicating the manufacturing process
Solution Approach 2:
The electrode configuration is made non-uniform by extending individual electrodes beyond the pressure chamber boundaries in specific locations. This creates local variations in the electric field distribution, enabling enhanced piezoelectric deformation in critical areas while maintaining simple electrode formation methods elsewhere, thus resolving the contradiction between manufacturing simplicity and drive efficiency
2Stress or pressure
If drive voltage is applied continuously to maintain pressure, then pressure is maintained, but polarization deterioration occurs in the piezoelectric layer, reducing durability
Solution Approach 1:
Instead of continuous voltage application, the system uses periodic pulsed voltage signals that coincide with the ink discharge timing. The piezoelectric actuator receives voltage pulses only when ink ejection is required, creating periodic action that maintains pressure when needed while preventing continuous polarization deterioration, thereby improving durability without sacrificing pressure capability
Solution Approach 2:
The extended electrode design enables more effective pressure generation during the active discharge phase, making the periodic voltage application more efficient. The increased piezoelectric deformation area allows the brief voltage pulses to generate sufficient pressure waves for complete ink ejection, maintaining continuous useful action during discharge while eliminating wasted voltage application during non-discharge periods
Data Source
AI summary
A piezoelectric actuator includes a vibration plate 30 covering pressure chambers 14 and serving also as a common electrode, a piezoelectric layer 31 arranged on the vibration plate 30 on a side opposite to the pressure chambers 14, and individual electrodes 32. The individual electrodes are each arranged on a surface of the piezoelectric layer 31 opposite to the vibration plate 30, in an area overlapping with an edge portion of the pressure chamber as viewed from a direction orthogonal to a plane in which the pressure chambers are arranged, the edge portion being an area other than the central portion of the pressure chamber. The individual electrodes are extended up to an area outside of the pressure chambers, as viewed from the direction orthogonal to the plane. A liquid transporting apparatus including the piezoelectric actuator has an excellent durability and improved drive efficiency.