Liquid Ejection Head Pulse Interval Timing
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Solution Overview
Problem
In liquid ejection systems with multiple nozzles, pressure interference and fluctuation lead to variations in ejection velocity between central and end nozzles, affecting the uniformity of droplet ejection.
Innovation Solution
A driving waveform with specifically timed pulse intervals is applied to the pressure generator, where the interval between driving pulses is set to minimize pressure differences in individual liquid chambers caused by a common liquid chamber, using the formula Tn = n×Tc/2 + x0, where Tn is the pulse interval, Tc is the natural vibration period, and x0 is the time from a pressure peak to residual pressure fluctuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple nozzles are simultaneously driven to increase productivity, then the ejection velocity uniformity deteriorates due to pressure interference and pressure fluctuation in the common liquid chamber
Solution Approach 1:
The patent applies periodic action by setting the pulse interval between continuous driving pulses to a specific timing relationship with the natural vibration period of the individual liquid chambers. The pulse interval is set to an integer multiple of the natural vibration period, creating a periodic driving pattern that synchronizes with the chamber's natural oscillation. This periodic timing allows pressure fluctuations to reset between pulses, enabling multiple nozzles to be driven simultaneously while maintaining uniform ejection velocity across all nozzles.
2Productivity
If driving pulses are applied continuously to eject multiple droplets, then the ejection velocity consistency deteriorates due to residual pressure fluctuation in the common liquid chamber
Solution Approach 1:
The patent applies preliminary action by carefully selecting the pulse interval timing before the next driving pulse is applied. The pulse interval is set to allow the pressure fluctuation in the common liquid chamber to return to a stable state before the subsequent pulse. This preliminary timing adjustment ensures that each driving pulse starts from a consistent pressure baseline, maintaining ejection velocity consistency while enabling continuous high-rate droplet ejection.
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 reduces variations in ejection velocity across nozzles, ensuring more uniform droplet ejection by aligning the timing of pressure fluctuations, thereby improving the consistency of droplet formation and merging during flight.
Implementation Method 1
Tc denotes a natural vibration period of the individual liquid chambers
Implementation Method 2
a pressure generator to generate a pressure for pressing liquid in the individual liquid chambers
Data Source
AI summary
An apparatus for ejecting liquid, includes a liquid ejection head with a plurality of individual liquid chambers and a common liquid chamber, and a pressure generator to generate a pressure for pressing liquid in the individual liquid chambers. A pulse interval, which is a time from the end of a push-in waveform element of a preceding driving pulse to the start of a pull-in waveform element of a succeeding driving pulse in the two continuous driving pulses is set to a timing when a pressure difference among the pressure fluctuations in the individual liquid chambers, caused by the pressure fluctuation in the common liquid chamber, becomes smaller.