TIR Reflective Image Display Dielectric Coating for Pinhole Resistance
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Solution Overview
Problem
Conventional total internal reflection (TIR)-based reflective image displays face challenges in achieving uniform dielectric properties over convex protrusions, leading to non-uniform dielectric coatings that can result in pinholes, moisture ingress, and suboptimal electrical properties, which affect the display's performance and longevity.
Innovation Solution
The use of atomic layer deposition (ALD) and other methods to deposit conformal dielectric layers with controlled thickness and composition on the electrodes and pixel walls, comprising materials like AlOx and SiO2, to enhance the uniformity and integrity of the dielectric coating, thereby improving resistivity, permittivity, and surface properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional deposition methods are used to form dielectric layers on convex protrusions, then the manufacturing process is simpler, but the dielectric coating uniformity deteriorates leading to pinholes and moisture ingress
Solution Approach 1:
The patent employs atomic layer deposition (ALD) which fundamentally changes the deposition parameters and mechanism compared to conventional methods. ALD uses sequential surface reactions with precise control of precursor exposure timing and temperature, enabling conformal coverage on convex protrusions with uniform thickness control at the nanometer scale, directly resolving the uniformity issue while accepting increased process complexity.
Solution Approach 2:
The patent replaces conventional physical vapor deposition or spin-coating methods with chemical vapor deposition through ALD. This substitution uses chemical reactions rather than mechanical deposition, allowing the dielectric material to conformally coat complex three-dimensional surfaces including convex protrusions, achieving uniform coverage that mechanical methods cannot provide.
2Reliability
If dielectric layers are deposited on electrodes with convex structures, then the electrical insulation is improved, but non-uniform deposition causes pinholes and reduces reliability
Solution Approach 1:
The patent uses ALD process parameters including controlled temperature (typically 100-200°C), precise precursor exposure timing, and pressure control to achieve uniform dielectric layer deposition. These parameter changes ensure complete coverage over convex structures without pinholes, directly improving display reliability and longevity by preventing moisture ingress and maintaining electrical insulation.
Solution Approach 2:
The patent introduces a conformal dielectric layer as an intermediary between the electrode with convex protrusions and the external environment. This intermediate layer, deposited uniformly through ALD, prevents direct contact between moisture/oxygen and the electrode structure, thereby improving reliability by blocking degradation pathways while maintaining electrical functionality.
3Reliability
If conformal dielectric layers are deposited using ALD, then moisture resistance and electrical properties are improved, but the manufacturing cost and process time increase
Solution Approach 1:
The patent employs ALD with optimized cycle times, temperature parameters, and precursor selection to achieve conformal dielectric layers with excellent moisture barrier properties. While ALD is inherently slower than conventional methods, the parameter optimization enables practical manufacturing speeds while maintaining the critical uniformity and moisture resistance required for display reliability.
Solution Approach 2:
The patent applies multiple thin ALD cycles to build up the dielectric layer incrementally, achieving superior conformality and moisture resistance through repeated thin deposits rather than attempting to deposit thick layers in single steps. This partial action approach ensures complete coverage of convex structures while managing overall process time.
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 conformal dielectric layers provide improved resistance to moisture ingress, reduce pinholes, and enhance electrical properties, resulting in better contrast ratios and faster switching speeds in TIR-based displays.
Implementation Method 1
The conformal dielectric layers provide improved resistance to moisture ingress
Implementation Method 2
electrophoretically mobile particles move in response to a bias between two opposing electrodes
Implementation Method 3
Light rays incident upon the interface at angles greater than Θc may undergo TIR at the interface
Implementation Method 4
a dielectric layer located on the surface of at least one electrode formed by one or more of methods of atomic layer deposition
Data Source
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AI summary
Semi-retro-reflective total internal reflection-based image displays may be equipped with at least one dielectric layer. The at least one dielectric layer may be deposited on one or more of a front electrode layer, rear electrode layer or pixel walls. This may lead to displays with enhanced brightness, improved electrophoretic particle responsiveness, improved grayscale and chemical stability in the presence of an electrophoretic medium, and improved resistance to high electric fields and high temperatures. In one embodiment, a total internal reflection-based image display comprises a dielectric layer formed by one or more of methods molecular layer deposition, atomic layer deposition, chemical vapor deposition, plasma enhance chemical vapor deposition, spin coating or slot die coating. In another embodiment, a total internal reflection-based image display comprises at least one dielectric layer and at least one surface modification layer.