Piezoelectric Actuator Electrode Layout for Droplet Ejection Consistency
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Solution Overview
Problem
High-density pressure chamber arrangements in ink-jet printers lead to crosstalk issues and variations in droplet ejecting speed and volume due to misalignment and shifting of piezoelectric actuators relative to the cavity unit, causing asymmetrical volume changes in pressure chambers.
Innovation Solution
A droplet ejecting apparatus with a piezoelectric actuator having comb-like first and second potential electrodes, where individual electrodes are arranged to overlap the second trunk portion of the second potential electrode, ensuring symmetrical volume change characteristics regardless of actuator misalignment, and connecting portions are disposed on the same side of the pressure chambers to minimize crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pressure chambers are arranged at high density to increase nozzle density, then image quality and recording quality improve, but crosstalk occurs between adjacent pressure chambers during actuator driving
Solution Approach 1:
The piezoelectric actuator is divided into multiple independent active portions (first active portions corresponding to central portions of pressure chambers, second active portions corresponding to outer peripheral portions). Each active portion can be independently controlled by separate electrodes, allowing selective actuation of individual pressure chambers without interfering with adjacent ones, thus suppressing crosstalk while maintaining high density arrangement
Solution Approach 2:
Different portions of the piezoelectric actuator are given different functions: first active portions for central pressure chamber regions and second active portions for outer peripheral regions. This local differentiation allows precise control of each pressure chamber region, enabling high-density arrangement without crosstalk by addressing each region's specific actuation needs
2Device complexity
If connecting portions of individual electrodes are disposed on the same side to reduce actuator size, then device complexity decreases, but asymmetrical volume changes occur in pressure chambers due to misalignment
Solution Approach 1:
The connecting portions of individual electrodes are deliberately arranged asymmetrically on the same side of the pressure chambers. This asymmetric configuration, combined with the complementary arrangement of first and second active portions, compensates for misalignment between the actuator and cavity unit, ensuring symmetrical volume changes in pressure chambers regardless of shift amount
Solution Approach 2:
The asymmetric arrangement of connecting portions is designed in advance to counteract the harmful effects of misalignment. By pre-configuring the electrodes in this specific asymmetric pattern, the patent eliminates the need for precise alignment during assembly, automatically compensating for any shift between actuator and cavity unit
3Ease of manufacture
If first and second constant potential electrodes overlap in superposition direction, then manufacturing is simplified, but foreign substances cause cracks and short circuits reducing withstand pressure
Solution Approach 1:
Instead of overlapping electrodes in the superposition direction (vertical dimension), the patent arranges first and second constant potential electrodes side-by-side in the horizontal direction. This dimensional shift eliminates the overlapping problem that causes foreign substance accumulation while maintaining electrical functionality through the comb-like structure with multiple branch portions
4Productivity
If piezoelectric actuator is bonded to cavity unit, then droplet ejection function is achieved, but misalignment causes variations in droplet ejecting speed and volume among pressure chambers
Solution Approach 1:
The piezoelectric actuator with its multi-portion structure serves multiple functions simultaneously: it actuates multiple pressure chambers, compensates for misalignment, and maintains consistent droplet ejection across all chambers. The first and second active portions work together to provide both central and peripheral actuation, ensuring uniform performance regardless of bonding alignment
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 reduces variations in droplet ejecting speed and volume among pressure chambers, enhancing the reliability and consistency of ink ejection by maintaining symmetrical volume change characteristics even with actuator shifting, thus improving image quality without increasing the number of electrodes or signal lines.
Implementation Method 1
a piezoelectric actuator joined to the cavity unit for permitting a liquid in each pressure chamber to be selectively ejected
Data Source
AI summary
A droplet ejecting apparatus, including: a head having a cavity unit with pressure chambers and a piezoelectric actuator; and a voltage application device, the actuator including: first and second active portions; a first potential electrode; a second potential electrode including a second trunk portion; and individual electrodes each having a connection portion, wherein the connection portion is disposed to overlap the second trunk portion as seen in a superposition direction of the cavity unit and the actuator, wherein the individual electrodes are arranged in rows to correspond to rows of the pressure chambers, and all connecting portions belonging to any one row are disposed on the same side in a direction of arrangement of the rows, and wherein the connecting portions of the individual electrodes that belong to one and the other of any adjacent two rows are disposed on mutually opposite sides with respect to the corresponding pressure chambers.