Staggered Drive Waveforms for Piezoelectric Inkjet Nozzle Stability
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Solution Overview
Problem
In liquid ejection apparatuses, such as inkjet printers, the concentration of electric current and pressure oscillations between channels can lead to unstable liquid ejection when a large number of actuators are driven simultaneously, especially when they are close to each other, resulting in uneven ink distribution and print quality issues.
Innovation Solution
The solution involves applying drive waveforms with opposite phases and delayed timing to actuators connected to a common electrode, ensuring that at least one actuator is not driven simultaneously with others, and using a memory-based delay allocation table to adjust the drive circuit, which helps in stabilizing the liquid ejection by reducing current concentration and pressure oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large number of actuators are driven simultaneously, then liquid ejection speed is improved, but current concentration and pressure oscillation increase causing ejection instability
Solution Approach 1:
The patent applies periodic action by driving actuators in sequential phases rather than simultaneously. The drive signal is divided into multiple phases where different actuator groups are activated at different times, creating a periodic driving pattern that prevents current concentration while maintaining high ejection throughput.
Solution Approach 2:
The patent segments the actuator array into multiple groups that can be driven independently at different times. By dividing the actuators into first, second, third, and fourth actuator groups with staggered drive timing, the system avoids simultaneous current concentration while maintaining overall ejection productivity.
2Productivity
If actuators are positioned close to each other, then device density is improved, but pressure oscillation between channels increases causing ejection instability
Solution Approach 1:
By implementing periodic driving phases where adjacent actuator groups are activated at different times, the patent eliminates pressure oscillation between closely spaced channels. The sequential activation ensures that pressure waves from adjacent actuators do not interfere with each other, allowing high device density while maintaining ejection stability.
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 stabilizes liquid ejection by minimizing voltage drops and pressure oscillations, resulting in improved ink ejection speed and uniformity, thereby enhancing print quality and consistency.
Implementation Method 1
a piezoelectric actuator (8) having a first electrode (63, 65) and a second electrode (64, 66), and a pressure chamber (5) connected to the first electrode (63, 65) and the second electrode (64, 66)
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A liquid ejection apparatus includes a liquid ejection unit with a plurality of nozzles and a corresponding plurality of actuators. A drive waveform generation circuit is configured to generate drive waveforms having different drive timings. An actuator drive circuit is configured to apply a first drive waveform to a first actuator in a liquid ejection operation and a second drive waveform to a second actuator in the liquid ejection operation during which the first and second actuators are to be driven at a same nominal time. The first driving waveform is different from the second drive waveform, and the first actuator is at a position electrically closer along a predetermined direction to a power supply electrode than is the second actuator.