Inkjet Head Drive Waveform for Stable Droplet Ejection
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Solution Overview
Problem
Existing liquid ejection heads in inkjet printers face issues with satellite droplet formation and ink mist generation, while also being prone to latch-up phenomena due to electrical crosstalk and large voltage fluctuations, which affect ejection stability and performance.
Innovation Solution
A drive waveform is implemented in the liquid ejection head that includes an auxiliary pulse, ejection pulse, cancel pulse, and damping pulse, with specific durations and timing to prevent latch-up and stabilize ejection, using a shear mode shared wall type inkjet head with piezoelectric actuators and a drive circuit to control the pressure chamber volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a drive waveform with expansion pulse and damping pulse is used to prevent satellite drops and ink mist, then ejection stability is improved, but electrical crosstalk and voltage fluctuation increase causing latch-up phenomenon
Solution Approach 1:
The patent applies preliminary action by introducing an expansion pulse before the damping pulse to proactively prepare the pressure chamber state. The expansion pulse expands the pressure chamber volume to a state where ink is not ejected, which prevents the conditions that would lead to satellite drops and ink mist formation, thereby maintaining ejection stability without requiring excessive damping pulse intensity that would cause electrical crosstalk.
Solution Approach 2:
The patent employs periodic action through a multi-stage drive waveform consisting of expansion pulse, ejection pulse, cancel pulse, and damping pulse applied in sequence. This periodic sequence of pulses creates controlled cycles of pressure chamber expansion and contraction, allowing the system to maintain stable ejection while using optimized pulse widths and intervals that minimize electrical crosstalk between adjacent actuators.
2Reliability
If expansion pulse width is increased to prevent satellite drops, then ejection stability is improved, but voltage fluctuation in adjacent actuators increases due to electrical crosstalk
Solution Approach 1:
The patent applies parameter changes by optimizing the pulse widths of expansion pulse, ejection pulse, cancel pulse, and damping pulse to specific ranges. By carefully controlling the duration of each pulse type and the intervals between them, the system achieves stable ejection performance while keeping the voltage fluctuation in adjacent actuators within acceptable limits, thus preventing latch-up phenomenon.
3Adaptability or versatility
If multiple pulses are used to control ejection amount without changing head structure, then adaptability is improved, but device complexity increases due to multiple waveform components
Solution Approach 1:
The patent applies universality by designing a multi-functional drive waveform where a single integrated pulse sequence (expansion + ejection + cancel + damping pulses) performs multiple functions: controlling ejection amount, preventing satellite drops, eliminating ink mist, and maintaining ejection stability. This universal waveform structure allows the system to achieve various ejection requirements without modifying the physical head structure, while the modular nature of the pulse sequence keeps the control logic manageable.
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 ensures stable ejection performance by preventing latch-up and maintaining uniform ejection speed and dot landing, while minimizing electrical crosstalk and voltage fluctuations, thereby enhancing printing quality and resolution.
Implementation Method 1
a plurality of piezoelectric elements corresponding to the pressure chambers, and a drive device that applies a drive signal to the piezoelectric elements
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 pressure chamber being varied to eject the liquid from the nozzle, an actuator configured to vary the volume of the pressure chamber in response to a drive signal, and a drive circuit configured to generate the drive signal. The pressure chamber has one of states including: a steady state in which the volume is unchanged, an expanded state in which the volume is expanded, and a contracted state in which the volume is contracted. The drive signal includes first through fourth waveforms. A duration of the fourth waveform is shorter than a duration of the third waveform, and is at least 1 μs or 0.5 times a half cycle of a main acoustic resonance frequency of the liquid in the pressure chamber.