Nozzle Coating Taper for Display Inkjet Precision
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Solution Overview
Problem
Existing display device manufacturing methods face challenges in adjusting nozzle diameters and improving ink ejection rates and characteristics, limiting the precision and efficiency of organic light-emitting display device production.
Innovation Solution
An apparatus with a head unit featuring a nozzle unit and a first coating portion with a Venturi tube or orifice shape, where the thickness of the coating portion narrows towards the top, and an ink reservoir with specific passage configurations, enhances nozzle diameter adjustment and ink ejection characteristics, utilizing a piezoelectric ejection controller and deposition processes for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional inkjet head structure is used, then the manufacturing process is simple, but the nozzle diameter cannot be precisely adjusted and ink ejection characteristics are poor
Solution Approach 1:
The head unit is divided into multiple functional components: nozzle unit, first coating portion, second coating portion, ink reservoir, and ejection controller. The coating portions are further segmented into multiple layers with different thickness profiles. This segmentation allows independent optimization of each component's function, enabling precise nozzle diameter control through the tapered third portion while maintaining manufacturing feasibility through modular assembly.
Solution Approach 2:
Different portions of the coating structure have different thickness characteristics tailored to specific functions: the first and second coating portions have relatively uniform thickness for structural support and protection, while the third coating portion has a tapered thickness profile (thinner at the top) specifically at the nozzle outlet to control ink ejection. This local differentiation of quality enables precise control of ink flow characteristics without compromising overall structural integrity.
2Manufacturing precision
If the nozzle diameter is reduced for higher resolution, then the display resolution improves, but the ink ejection rate decreases
Solution Approach 1:
The invention changes the geometric parameters of the nozzle structure, specifically implementing a tapered coating thickness in the third portion where the thickness decreases toward the top. This parameter modification creates a controlled expansion of the ink passage at the outlet, allowing smaller nominal nozzle diameters (for high resolution) to maintain adequate ink ejection rates by optimizing the flow channel geometry rather than simply increasing nozzle size.
Solution Approach 2:
The multi-layer coating structure with varying thicknesses creates a dynamic flow profile for the ink. The tapered third portion acts as a gradual expansion zone that accelerates ink flow toward the outlet, compensating for the smaller nozzle diameter. This dynamic flow management allows high resolution printing while maintaining sufficient ejection rate through optimized fluid dynamics rather than static geometry alone.
3Productivity
If the ink ejection force is increased to improve ejection rate, then the ink ejection rate improves, but the head unit may be damaged
Solution Approach 1:
The first and second coating portions serve as protective layers that cushion and distribute mechanical stresses within the head unit. The first coating portion covers the bottom surface and provides baseline protection, while the second coating portion adds an additional protective layer. These pre-installed protective structures prevent damage to underlying components during high-force ink ejection operations, enabling higher ejection rates without compromising head unit reliability.
Solution Approach 2:
The head unit employs a composite structure with multiple coating materials applied in sequence. The first coating portion and second coating portion may use different materials with complementary properties - one providing structural strength and another providing protective characteristics. This composite approach creates a multi-functional protective system that can withstand the mechanical stresses of high-rate ink ejection while protecting the head unit from damage.
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 apparatus allows for precise control of nozzle diameters and ink ejection rates, enhancing the resolution and durability of display devices by optimizing ink ejection characteristics and preventing damage to the head unit.
Implementation Method 1
the first coating portion has a Venturi tube shape or an orifice shape
Implementation Method 2
the ejection controller comprises a piezoelectric element
Implementation Method 3
the first coating portion is formed by a physical vapor deposition process
Data Source
AI summary
An apparatus for manufacturing display devices includes: a stage; and a head unit disposed on the stage and including a nozzle unit. The head unit further includes a first coating portion covering a bottom surface of the head unit and at least a part of an inner surface of the nozzle unit, and where a thickness of at least a part of the first coating portion becomes narrower toward a top of the first coating portion.