Inkjet Head Flushing Pulse Timing for Viscosity Recovery
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Solution Overview
Problem
Inkjet printers face ejection faults due to increased ink viscosity caused by solvent evaporation, leading to decreased ejection weight and velocity, and unstable meniscus conditions during flushing operations, which can result in image quality deterioration and excessive ink consumption.
Innovation Solution
A liquid ejecting apparatus with a pressure generating member driven by a driving signal comprising a first driving pulse for flushing, including a voltage variation element to expand and sustain the pressure chamber, and a second voltage variation element to compress it, applied in a manner that resonates with the inherent vibration cycle of the ink, effectively reducing viscosity and stabilizing the meniscus for improved ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high pressure fluctuation is applied to ink during flushing to forcibly remove high viscosity ink and bubbles, then the ejection ability is recovered, but residual vibration increases causing meniscus instability and curved ink flight
Solution Approach 1:
The patent applies periodic flushing operations with controlled pulse intervals. The driving pulse is designed with specific timing characteristics including a voltage sustaining element that maintains voltage for a predetermined period, creating controlled periodic pressure fluctuations that recover ejection ability while allowing meniscus stabilization between pulses.
Solution Approach 2:
The patent dynamically adjusts the driving pulse characteristics based on operational conditions. The driving pulse includes variable elements such as voltage sustaining duration and amplitude that can be modified to balance between forcing high viscosity ink removal and minimizing residual vibration that causes meniscus instability.
2Reliability
If driving pulse for flushing is repeatedly applied to continuously eject high viscosity ink, then ejection ability is maintained, but ink consumption increases significantly
Solution Approach 1:
The patent applies flushing operation selectively rather than continuously. The control unit determines when flushing is necessary based on predetermined conditions such as elapsed time since last recording operation or detected ejection abnormalities. This partial application of flushing maintains ejection ability while avoiding unnecessary ink consumption during normal operation.
3Reliability
If capping member seals the nozzle surface to suppress evaporation, then solvent evaporation is reduced, but a space between capping member and nozzle surface allows residual evaporation
Solution Approach 1:
The patent extracts and addresses the specific problem of residual evaporation from the space between capping member and nozzle surface by implementing targeted flushing operations. Rather than modifying the capping structure itself, the solution removes the harmful effect (evaporated solvent causing viscosity increase) through controlled ink ejection that clears the ink passage and replenishes ink at the nozzle surface.
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 recovers the ejection ability of the inkjet printer by reducing ink viscosity and stabilizing the meniscus, enhancing the accuracy and efficiency of ink ejection while minimizing ink consumption.
Implementation Method 1
a piezoelectric vibrator 30 that acts as the pressure generating element and varies the volume of the pressure chamber 38
Implementation Method 2
the natural vibration cycle of ink in the pressure chamber 38 is 1/2 the time span from the front end of the expansion element to the front end of the contraction element
Data Source
AI summary
A resonance pulse is a voltage waveform substantially containing an expansion element for varying a voltage to expand a pressure chamber, an expansion sustaining element generated following with the expansion element, and sustaining a maximum voltage at a predetermined value, and a contraction element generated following with the expansion sustaining element, and varying the voltage to contract the pressure chamber. A time span from a front end of the expansion element to a front end of the contraction element is set as ½ of an inherent vibration cycle of ink in the pressure chamber.