Inkjet Nozzle Geometry for Uniform Droplet Velocity
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Solution Overview
Problem
The existing liquid droplet ejection apparatuses, such as ink-jet heads, face challenges in maintaining uniformity and reducing production costs due to nonuniform structures and variations in nozzle diameters, which can lead to uneven deformation and increased production costs.
Innovation Solution
A liquid droplet ejection apparatus with nozzles of different diameters and lengths, where the tip opening diameter of the black ink nozzle is larger than that of the color ink nozzle, and the length of the black ink nozzle is shorter, allowing for equal flying speeds of ink droplets using a pressure generating unit and a manufacturing method involving laser beam emission to form nozzles with varying dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If nozzles have different diameters to satisfy different printing modes (high-resolution image vs. solid image), then printing versatility is improved, but production cost increases due to nonuniform piezoelectric actuator structure
Solution Approach 1:
The patent applies local quality by varying the nozzle diameter at different locations (color ink nozzles have smaller diameter for high-resolution printing, black ink nozzles have larger diameter for solid image printing) while keeping the piezoelectric actuator structure uniform. This allows different printing modes to be satisfied through local nozzle geometry differences rather than actuator structure differences, thereby reducing production cost.
Solution Approach 2:
The patent makes the piezoelectric actuator universal by using the same actuator structure for all nozzles regardless of nozzle diameter. The uniform actuator design can serve multiple functions (driving both color and black ink nozzles) without requiring customization, which simplifies manufacturing and reduces production cost while maintaining versatility through nozzle geometry variation.
2Manufacturing precision
If piezoelectric actuator has nonuniform structure with varied active part length and electrode width for each nozzle diameter, then droplet ejection performance is improved, but manufacturing precision deteriorates due to deformation during baking
Solution Approach 1:
The patent applies homogeneity by making the piezoelectric actuator structure uniform across all nozzles, with consistent active part length and electrode width. This uniform structure maintains stability during the baking process and prevents deformation, while droplet ejection performance is optimized through nozzle geometry variation rather than actuator variation.
3Manufacturing precision
If nozzle diameter is increased for black ink to eject larger droplets, then solid image printing quality is improved, but droplet flying speed uniformity deteriorates
Solution Approach 1:
The patent applies parameter changes by varying the nozzle diameter parameter (larger for black ink, smaller for color ink) to achieve different droplet sizes suitable for different printing modes. The larger black ink nozzle diameter enables larger droplets for solid image printing, while the smaller color ink nozzle diameter enables finer droplets for high-resolution printing.
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 configuration enables equal flying speeds of ink droplets from nozzles with different diameters, reducing the need for varying active parts in the piezoelectric actuator, thereby lowering production costs and minimizing deformation variations, and allowing for efficient gradation printing.
Implementation Method 1
The piezoelectric actuator includes piezoelectric sheets each being sandwiched by a common electrode and a plurality of individual electrodes. Herein, a required individual electrode is applied with voltage to selectively impart pressure to a corresponding ink flow path, so as to generate ink ejecting pressure.
Implementation Method 2
emitting a first laser beam to the nozzle plate through the outflow path in the semi-nozzle plate to form a nozzle for the first liquid; and emitting a second laser beam to the semi-nozzle plate and the nozzle plate to form a nozzle for the second liquid
Data Source
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AI summary
A liquid droplet ejection apparatus includes: a flow path unit (2) including first and second pressure chambers (33) for first and second liquids, respectively, and first and second nozzles communicating with the first and second pressure chambers (35), respectively, each of the first and second nozzles including a tip opening; and a pressure generating unit (3) which generates a pressure for the liquids in the first and second pressure chambers to eject the liquids through the tip openings of the first and second nozzles (38,39). A diameter of the tip opening of the first nozzle (17a) is larger than that of the tip opening of the second nozzle (17b) and a length of the first nozzle (38) is shorter than that of the second nozzle (39).