Piezoelectric Inkjet Nozzle Control via Residual Vibration Sensing
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Solution Overview
Problem
Existing liquid jetting apparatuses face challenges in accurately evaluating and adjusting jetting characteristics due to variations in liquid viscosity, particularly when switching between continuous and single jetting modes, leading to an excessive load on manufacturers who assemble the apparatuses.
Innovation Solution
Incorporation of a detection mechanism to measure residual vibrations in the piezoelectric element, allowing for the evaluation and adjustment of jetting characteristics by detecting and analyzing first and second residual vibrations during continuous and discontinuous vibration driving, enabling the determination of appropriate minute vibration waveforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-jetting driving is performed to suppress liquid thickening, then jetting characteristic variations are reduced, but device complexity increases due to the need for detection mechanisms and control systems
Solution Approach 1:
The patent replaces complex mechanical detection systems with piezoelectric elements that serve dual functions: jetting actuation and residual vibration detection. The piezoelectric element converts mechanical vibration into electrical signals, enabling simple electronic measurement of residual vibrations without additional mechanical sensors.
Solution Approach 2:
The piezoelectric element performs multiple functions: it acts as both the jetting actuator (converting electrical signals to mechanical vibration) and the detection sensor (converting residual mechanical vibration back to electrical signals). This multi-functionality eliminates the need for separate detection mechanisms, reducing device complexity while maintaining reliability.
2Reliability
If minute vibration driving is continuously performed to maintain consistent jetting characteristics, then jetting stability is improved, but energy consumption increases
Solution Approach 1:
Instead of continuous minute vibration driving, the system performs periodic detection of residual vibrations and applies minute vibration pulses only when needed to correct deviations. This periodic intervention maintains jetting stability while significantly reducing energy consumption compared to continuous operation.
Solution Approach 2:
The system implements feedback control by detecting residual vibrations after each jetting operation and adjusting subsequent minute vibration pulses accordingly. The control unit modifies the vibration waveform based on detected residual vibration levels, maintaining jetting consistency with minimal energy input by applying corrections only when deviations occur.
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 allows for precise evaluation and reduction of jetting characteristic variations, alleviating the burden on manufacturers by providing a systematic method to adjust and stabilize jetting performance.
Implementation Method 1
a piezoelectric element which corresponds to the nozzle, a vibration plate which vibrates by driving the piezoelectric element
Implementation Method 2
a detection portion which detects residual vibration of the vibration plate caused by driving of the piezoelectric element
Data Source
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AI summary
A liquid jetting apparatus includes a liquid jetting head including a nozzle, a piezoelectric element, a vibration plate, and a detection circuit which detects residual vibration of the vibration plate and an evaluation control portion, in which the evaluation control portion causes the detection circuit to detect, as first residual vibration, residual vibration caused by continuously performing jetting driving in which the piezoelectric element is driven with a vibration pulse for generating, at the vibration plate, vibration larger than vibration of the vibration plate caused by non-jetting driving in which the piezoelectric element is driven with a minute vibration pulse for not jetting an ink from the nozzle, causes the detection circuit to detect, as second residual vibration, residual vibration caused by continuously driving the piezoelectric element in order of the non-jetting driving and the jetting driving, and evaluates a variation in a jetting characteristic of the nozzle between a case where the jetting driving is continuous and a case where the jetting driving is not continuous based on the first residual vibration and the second residual vibration.