Ink Droplet Ejection Nozzle Sedimentation Prevention
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Solution Overview
Problem
Liquid droplet ejection apparatuses face challenges in preventing sedimentation of solid particles in inks, leading to nozzle clogging and irregular ejection rates, as existing methods either fail to address sedimentation effectively or increase viscosity, which is not sustainable for long-term stable operation.
Innovation Solution
A liquid droplet ejection apparatus that employs micro-vibration pulses and ejection pulses to maintain kinetic energy in solid particles, ensuring their dispersion and preventing sedimentation, combined with an ink circulation system to maintain uniform concentration, thereby stabilizing droplet ejection over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid particles with higher specific gravity than dispersion medium are used in ink, then pigment performance is improved, but sedimentation occurs in ink chamber leading to nozzle clogging
Solution Approach 1:
The patent applies mechanical vibration to the ink chamber to prevent sedimentation of solid particles. The vibration agitates the ink, keeping solid particles suspended and preventing them from settling at the bottom of the ink chamber, thereby eliminating the root cause of nozzle clogging while maintaining the desired pigment performance.
Solution Approach 2:
The patent implements periodic vibration cycles in the ink chamber. By applying vibration intermittently rather than continuously, the system maintains particle suspension effectively while reducing energy consumption and avoiding excessive agitation that could introduce air bubbles or cause other operational issues.
2Productivity
If ink circulation is implemented using pressure difference between head and ink tank, then ink supply is improved, but sedimentation in individual ink chambers cannot be suppressed
Solution Approach 1:
The patent divides the ink system into separate individual ink chambers, each capable of independent vibration. This segmentation allows each chamber to be agitated independently to prevent sedimentation, while the overall circulation system maintains efficient ink supply from the common ink tank to all chambers.
Solution Approach 2:
The patent combines individual chamber vibration mechanisms with the common ink circulation system. Each ink chamber receives both the circulated ink supply from the common tank and localized vibration treatment, merging the benefits of efficient bulk circulation with targeted sedimentation prevention at the chamber level.
3Reliability
If meniscus vibration is applied to eliminate nozzle clogging, then viscosity increase is addressed, but advanced sedimentation state cannot be sufficiently eliminated
Solution Approach 1:
The patent applies vibration to the ink chamber in advance, before the ink reaches the nozzle. This preliminary agitation prevents sedimentation from occurring in the first place, eliminating the need for corrective meniscus vibration at the nozzle level and ensuring uniform ejection from the start.
Solution Approach 2:
The patent uses the ink chamber as an intermediary zone where vibration is applied to prevent sedimentation before the ink reaches the nozzle. This intermediary treatment ensures that by the time ink reaches the ejection point, particles are already properly suspended, eliminating the need for additional corrective measures at the nozzle.
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 sedimentation and nozzle clogging, ensuring stable and uniform ejection of liquid droplets for extended periods by maintaining kinetic energy in solid particles and circulating ink to maintain uniform concentration.
Implementation Method 1
a vibration unit configured to vibrate the ink in the ink chamber
Implementation Method 2
an ejection unit configured to eject the liquid droplet from the nozzle by applying pressure to the ink in the pressure chamber
Data Source
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AI summary
Sedimentation of solid particles in an ink is affectively eliminated, and liquid droplets can be stably ejected for a long time. There is provided a liquid droplet ejection apparatus including: a head 1 that includes an ink chamber, a nozzle 12 provided in accordance with the ink chamber, and an energy giving device that gives energy to the ink in the ink chamber, the head performing printing on a print region of a recording medium C by ejecting liquid droplets from the nozzle 12; and a drive pulse generating device for generating, as the drive pulse, an ejection pulse that is used for ejecting the liquid droplets from the nozzle 12 and a micro-vibration pulse that micro-vibrates the ink in the ink chamber so as not to eject the liquid droplets from the nozzle 12, wherein the ink contains a dispersion medium and solid particles having higher specific gravity than that of a dispersion medium, and the liquid droplet ejection apparatus includes a refresh device for performing a micro-vibration operation for applying the plurality of micro-vibration pulses when the head is present in a non-print region, and an ejection operation for applying the plurality of rejection pulses after the micro-vibration operation and ejecting a liquid droplet amount equal to or greater than a capacity of the ink chamber from the nozzle 12.