Inkjet Head Drive Waveforms for Satellite Mist Suppression
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Solution Overview
Problem
Existing liquid ejection heads, such as inkjet printers, generate satellite mist during ink droplet ejection, leading to deteriorated print quality due to irregular landing.
Innovation Solution
A liquid ejection head with a drive circuit that generates specific drive waveforms to control the volume of pressure chambers, including a first contracted state followed by a second contracted state at a delayed timing, reducing satellite mist by adjusting the timing of pressure chamber transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional single contraction waveform is used, then the device complexity is low, but satellite mist is generated causing deteriorated print quality
Solution Approach 1:
The drive waveform is segmented into multiple contraction phases (first contraction phase and second contraction phase) with different timing characteristics. The first contraction phase contracts the pressure chamber to a first contracted state, and the second contraction phase subsequently contracts it to a second contracted state. This segmentation allows independent optimization of each phase to eliminate satellite mist while maintaining print quality.
Solution Approach 2:
The invention dynamically adjusts the timing of the second contraction phase relative to the first contraction phase. By controlling the time interval between the first and second contraction phases, the system optimizes the pressure chamber volume changes to prevent satellite droplet formation. The second contraction phase is timed to occur after the first, creating a dynamic timing relationship that eliminates harmful effects.
2Speed
If the pressure chamber is contracted quickly, then the ejection speed is high, but satellite mist is generated
Solution Approach 1:
The contraction process is divided into two sequential phases: a first contraction phase that rapidly contracts the pressure chamber to establish high ejection speed, followed by a second contraction phase that further contracts the chamber to eliminate satellite mist. This segmentation allows the system to achieve both high speed and quality by optimizing each phase independently.
Solution Approach 2:
The first contraction phase performs a preliminary contraction to establish the basic ejection flow and speed. The second contraction phase then performs an additional contraction action specifically targeted at eliminating satellite mist that formed during the first phase. This preliminary action followed by corrective action resolves the contradiction between speed and quality.
3Manufacturing precision
If a simple drive waveform is used, then the ease of operation is high, but landing accuracy deteriorates due to irregular droplet landing
Solution Approach 1:
The drive waveform is segmented into multiple controlled phases with specific timing relationships. The first contraction phase creates initial droplet ejection, and the second contraction phase refines the flow to ensure regular landing. This segmentation provides precise control over the ejection process, improving landing accuracy while maintaining operational simplicity through automated timing control.
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
The solution effectively reduces satellite mist and improves landing accuracy, achieving better print quality by minimizing irregular droplet landing.
Implementation Method 1
The inkjet head ejects the ink droplets from nozzles communicating with pressure chambers by changing their volumes with piezoelectric actuator elements
Implementation Method 2
AL is a half of a natural vibration period of the liquid in the pressure chamber
Data Source
AI summary
A liquid ejection head includes a nozzle, a pressure chamber that is capable of storing liquid and communicates with the nozzle, a volume of the chamber being variable to eject the liquid from the nozzle, an actuator configured to vary the volume in response to a drive signal, and a drive circuit configured to generate the signal. The chamber has one of states including a steady state in which the volume is unchanged, an expanded state in which the volume is expanded, a first contracted state in which the volume is contracted, and a second contracted state in which the volume is further contracted. The drive signal comprises a first waveform for transitioning from the steady state to the first contracted state, a second waveform for transitioning from the first to second contracted states, and a third waveform for transitioning from the second contracted state to the steady state.