Inkjet Head Drive Waveforms for Stable Droplet Ejection
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Solution Overview
Problem
Existing liquid ejection heads face issues with satellite droplet generation and ink mist formation, which affect ejection stability, and short expansion or damping pulses can cause electrical crosstalk leading to latch-up phenomena.
Innovation Solution
A liquid ejection head with a drive signal comprising specific waveforms, including an auxiliary, ejection, cancel, and damping pulse, where the damping pulse duration is shorter than the cancel pulse and at least 1 µs or 0.5 times the main acoustic resonance frequency, preventing electrical crosstalk and ensuring stable ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a short expansion pulse or damping pulse is used to prevent satellite drops and ink mist, then ejection stability is improved, but electrical crosstalk occurs in adjacent actuators causing latch-up phenomenon
Solution Approach 1:
The patent introduces a dummy actuator positioned adjacent to the actual actuator that receives the same drive signal in advance. This dummy actuator serves as a buffer to absorb electrical crosstalk before it reaches adjacent functional actuators, preventing latch-up phenomenon while allowing the use of short expansion and damping pulses for stable ejection
2Manufacturing precision
If drive waveform includes auxiliary pulse, ejection pulse, cancel pulse, and damping pulse to change ejection amount, then ejection precision is improved, but device complexity increases
Solution Approach 1:
The patent makes the dummy actuator serve multiple functions: it acts as an electrical buffer to prevent crosstalk, serves as a reference for drive signal timing, and enables the use of complex multi-pulse waveforms without affecting adjacent actuators. This multi-functionality allows precise ejection control while managing device complexity
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 stabilizes ejection performance, prevents latch-up, and maintains uniform dot landing by adjusting pulse durations, ensuring high ejection quality and stability.
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
Implementation Method 2
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 so that the fourth waveform does not cause the liquid to be ejected from the nozzle
Data Source
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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.