Asymmetric Micro-Vibration Waveform for Ink Thickening Prevention
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Solution Overview
Problem
Ink jet type recording apparatuses face issues with ink thickening at the nozzle opening, affecting ejection characteristics due to evaporation, and existing methods to prevent thickening, such as moving the head or generating micro-vibrations, are either ineffective or unclear in their efficacy.
Innovation Solution
A liquid ejecting apparatus with a pressure generation chamber and nozzle opening that uses a micro-vibration driving signal with a stronger pull than push to agitate the ink inside the chamber without ejecting it, optimizing the waveform and nozzle shape to suppress thickening, and incorporating a circulation path to maintain ink freshness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the ink jet type recording head is moved to a portion other than the media and the ink is discharged out appropriately before the ink is thickened, then the thickening of the ink droplets is suppressed, but the ink is ineffectively discarded
Solution Approach 1:
The patent applies mechanical vibration through a PZT (piezoelectric element) to generate micro-vibrations in the pressure generation chamber. This agitation prevents ink thickening by maintaining liquid flow and preventing stagnation, thereby suppressing evaporation and viscosity increase without requiring the head to be moved or ink to be discarded.
2Stability of the object's composition
If micro-vibrations are generated in the pressure generation chamber by a PZT or the like that is a pressure generation unit and the ink inside the pressure generation chamber is agitated, then the thickening of the ink is suppressed, but it is unclear whether or not the micro-vibration is appropriate enough to prevent the thickening of the ink
Solution Approach 1:
The patent employs periodic micro-vibration signals applied to the PZT to continuously agitate the ink in the pressure generation chamber. This periodic action ensures consistent prevention of ink thickening by maintaining regular liquid motion, making the thickening suppression reliable and predictable.
Solution Approach 2:
The patent optimizes parameters of the micro-vibration signal including frequency, amplitude, and waveform characteristics to achieve effective ink agitation. By adjusting these parameters, the system ensures that the micro-vibrations are sufficient to prevent thickening while avoiding excessive vibration that could cause other problems.
3Stability of the object's composition
If the ink is vibrated in the pressure generation chamber, then the thickening of the ink is suppressed, but the inclination of an expansion element and the inclination of a contraction element in the micro-vibration driving signal are usually the same as each other, resulting in ineffective thickening prevention
Solution Approach 1:
The patent introduces asymmetry in the micro-vibration driving signal by setting different inclinations for the expansion element and contraction element. Specifically, the expansion element has a gentler slope while the contraction element has a steeper slope, creating an asymmetric waveform that effectively drives ink from the nozzle opening back into the pressure generation chamber, thereby suppressing thickening at the nozzle opening.
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 prevents ink thickening by drawing high viscosity ink into the pressure generation chamber, maintaining favorable ejection characteristics and optimizing the agitating effect through a tapered nozzle shape, ensuring consistent ink delivery.
Implementation Method 1
a pressure generation unit which generates pressure to eject ink droplets using a pressure generation unit formed of a piezoelectric element
Implementation Method 2
vibrating a liquid inside a pressure generation chamber in the vicinity of a nozzle opening using a micro-vibration driving signal so as to agitate the liquid
Data Source
AI summary
A liquid ejecting apparatus includes: a liquid ejecting head having a pressure generation chamber in which a liquid is charged, a pressure generation unit which generates pressure change in the liquid inside the pressure generation chamber with supply of a driving signal, and a nozzle opening which ejects the liquid inside the pressure generation chamber according to the pressure change; and a control unit which has an expansion element expanding the pressure generation chamber and a contraction element contracting the pressure generation chamber, and supplies a micro-vibration driving signal to a piezoelectric element so as to generate the micro-vibration of the liquid to the inside of the pressure generation chamber without ejecting the liquid from the nozzle opening, wherein the micro-vibration driving signal is formed so that the inclination of the expansion element is greater than the inclination of the contraction element.