Laminated Piezoelectric Actuator Inkjet Printer
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Solution Overview
Problem
Conventional inkjet printers experience changes in piezoelectric characteristics over time, leading to variations in ink discharge efficiency due to the shift in spontaneous polarization of crystal grain units in the piezoelectric actuator, resulting in reduced ink discharge amount and speed.
Innovation Solution
The inkjet printer employs a laminated structure with additional electrodes to apply a specific signal to the laminated active portion, increasing the degree of c-axis orientation before use, which helps maintain stable piezoelectric characteristics by reducing stress-induced shape changes in the opposing portion, thus minimizing changes in ink discharge characteristics over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inkjet printer uses a piezoelectric actuator with a single piezoelectric film and electrodes to apply voltage for ink discharge, then ink discharge function is achieved, but piezoelectric characteristics change over time due to stress-induced shape changes in the opposing portion
Solution Approach 1:
The piezoelectric actuator is divided into multiple piezoelectric films (first piezoelectric film and second piezoelectric film) with separate electrode structures. The first piezoelectric film has first and second electrodes, while the second piezoelectric film has third and fourth electrodes. This segmentation allows independent control and stress distribution, preventing the stress-induced shape changes that occur in single-film structures and thereby maintaining stable piezoelectric characteristics over time.
Solution Approach 2:
Different regions of the piezoelectric actuator are given different functions through the laminated structure. The first piezoelectric film and its electrodes are optimized for one function while the second piezoelectric film and its electrodes handle another function. This local differentiation allows each layer to be optimized for its specific role, reducing overall stress and preventing characteristic drift during prolonged operation.
2Reliability
If the inkjet printer employs a laminated structure with additional electrodes to apply specific signals, then piezoelectric characteristics are stabilized, but device complexity increases
Solution Approach 1:
The second piezoelectric film with its third and fourth electrodes serves multiple functions: it acts as an opposing portion to the first piezoelectric film to prevent stress-induced shape changes, and simultaneously functions as an active piezoelectric element that can be driven by voltage applied between the third and fourth electrodes. This multi-functionality stabilizes ink discharge characteristics without requiring completely separate additional components, thereby limiting the increase in device complexity.
3Device complexity
If the inkjet printer uses a single piezoelectric film structure, then device complexity is low, but manufacturing precision requirements increase to ensure consistent performance
Solution Approach 1:
The piezoelectric actuator is segmented into multiple piezoelectric films with separate electrode structures. This segmentation allows each film and electrode pair to be manufactured and assembled with standard tolerances, rather than requiring a single complex structure with precise polarization alignment. The modular approach reduces manufacturing precision requirements while maintaining device performance through the combined action of multiple layers.
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 approach effectively stabilizes ink discharge characteristics, ensuring consistent performance even after prolonged use by suppressing changes in piezoelectric characteristics and maintaining efficient ink discharge.
Implementation Method 1
By applying voltage difference between the electrodes, the piezoelectric film deforms due to the piezoelectric effect. As a result, the piezoelectric actuator deforms.
Implementation Method 2
The generated pressure decrease develops a pressure wave within the pressure chamber. The developed pressure wave will propagate from the pressure chamber to the nozzle through an ink passage communicating the pressure chamber and the nozzle, and the pressure wave is reflected at the nozzle toward the pressure chamber.
Data Source
AI summary
An inkjet printer whose ink discharge characteristic will rarely change even when used for a long period of time is developed. The inkjet printer has a pressure chamber and a piezoelectric actuator and a controller. The piezoelectric actuator has a first electrode, a first piezoelectric film, a second electrode, a second piezoelectric film, and a third electrode, and they are laminated together in this order. The piezoelectric actuator forms a portion of the wall defining the pressure chanter. The controller applies ink discharge signal between the first and second electrode, ink discharge signal comprises advanced voltage change from a predetermined voltage to the lower voltage and subsequent voltage change from the lower voltage to the predetermined voltage. Ink can be effectively discharged by applying the ink discharge signal, but the ink discharge signal could change piezoelectric characteristic in the second piezoelectric film due to the deformation of the first piezoelectric film. The additional signal applying the second piezoelectric film via the second and the third electrode can reduce the changes of the piezoelectric characteristic. As a result, changes of ink discharge characteristic can be prevented.