Reflection Electrophoretic Display Ink-Jet Color Density Control
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Solution Overview
Problem
Reflection-type electrophoretic display panels face significant luminance reduction due to uneven density distribution in colored portions formed using ink-jet methods, particularly when displaying multi-color images with primary colors red, green, and blue, leading to decreased brightness and chroma saturation.
Innovation Solution
The implementation of an ink-jet method to form colored portions with precise control over ink ejection patterns and resin composition, ensuring a balanced area ratio and optimal ink viscosity, combined with the use of organic pigments and solvents, to achieve uniform color density across pixels, thereby enhancing luminance and color reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an ink-jet method is used to form colored portions on an electrophoretic display layer, then multi-color display capability is achieved, but luminance decreases significantly due to uneven density distribution in the colored portions
Solution Approach 1:
The patent applies local quality by creating colored portions with non-uniform density distribution where the center has lower density and the periphery has higher density. This local variation in density compensates for the natural light reflection characteristics of electrophoretic displays, achieving balanced color appearance without excessive luminance loss. The ink receiving layer is also designed with specific properties (porosity, hydrophilicity) to control local ink absorption and achieve the desired density distribution.
Solution Approach 2:
The patent changes multiple parameters to optimize the ink-jet printing process: ink composition (using dyes or pigments with specific concentration ranges), ink receiving layer properties (porosity, hydrophilicity, thickness), and printing parameters (number of passes, ink ejection amount). By adjusting these parameters, the patent achieves uniform color density across the colored portions while maintaining acceptable luminance for reflection-type display.
2Manufacturing precision
If the density of colored portions is increased to improve color saturation, then chroma saturation improves, but luminance decreases further due to light absorption
Solution Approach 1:
The patent uses local quality by designing the ink receiving layer with specific porosity and hydrophilicity to control where and how ink is absorbed. The layer is engineered to achieve optimal density distribution - sufficient for color saturation but not so dense as to block excessive light. This local optimization of the receiving layer properties balances chroma saturation and luminance.
Solution Approach 2:
The patent employs composite materials in the ink receiving layer, combining hydrophilic polymers with controlled porosity. This composite structure allows the layer to absorb and hold ink at optimal concentrations while maintaining light transmission properties. The composite nature of the receiving layer (polymer matrix with porous structure) enables simultaneous achievement of color density and luminance.
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 approach results in a reflection-type display panel capable of performing bright and vivid color displays with improved luminance and chroma saturation, addressing the issue of uneven density distribution and luminance loss associated with traditional methods.
Implementation Method 1
forming an ink receiving layer formed of a resin composition having an ink absorbing property on a transparent substrate, providing an ink from an ink-jet head with respect to the ink receiving layer to be colored
Implementation Method 2
a reflection-type display panel including an electrophoretic type display device... displays characters or images using reflected light
Data Source
Figure 1
Figure 2
Figure 3(a)~3(d)
AI summary
A reflection-type display panel of the present invention includes at least a substrate (10), a first electrode layer (11), a reflective display layer (13), a second electrode layer (14), a substrate, and an ink fixation layer in this order, a plurality of colored portions (15) formed using coloring compositions each including a pigment, a dispersant, a binder resin, and a solvent are provided on the ink fixation layer, a colored layer is arranged in accordance with driving units of the first electrode layer, and a ratio of the pigment to the binder resin contained in the colored layer is in the range of 1:9 to 5:5 by weight.