Dummy Color Filter Layer for LCD Luminance and Flatness
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Solution Overview
Problem
Liquid crystal display (LCD) panels face challenges in achieving high luminance due to the low luminance of non-emissive display devices, particularly because the addition of a white color filter in four-color pixel methods increases manufacturing costs and creates uneven light efficiency across regions due to additional processing and steps in the panel structure.
Innovation Solution
Incorporating a dummy color filter layer in the white sub-pixel area with a thickness ranging from 0.2 to 2 micrometers, which is either the same as or slightly thinner than the color filter layers in other sub-pixel areas, and is strategically positioned to minimize the step difference with adjacent color filter layers, thereby maintaining a uniform cell gap and reducing light transmittance loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a white color filter is added in the white sub-pixel area to achieve four-color pixel method, then luminance is improved, but manufacturing complexity and cost increase due to additional processing steps
Solution Approach 1:
The patent extracts the white color filter function from the traditional four-color pixel method and replaces it with a dummy color filter layer that has the same thickness as the color filter layers in red, green, and blue sub-pixel areas. This extraction eliminates the need for additional white color filter processing steps while maintaining uniform cell gap structure, thereby reducing manufacturing complexity without sacrificing luminance performance.
Solution Approach 2:
The patent creates a dummy color filter layer that copies the thickness and structural characteristics of the actual color filter layers (red, green, blue) in the white sub-pixel area. This copying approach allows the white sub-pixel to have the same structural profile as colored sub-pixels, eliminating the need for separate white color filter fabrication processes and reducing manufacturing complexity.
2Illumination intensity
If a white color filter is added in the white sub-pixel area, then luminance is improved, but light efficiency becomes uneven across regions due to additional processing steps
Solution Approach 1:
The patent applies local quality by making the dummy color filter layer in the white sub-pixel area have the same thickness as the color filter layers in red, green, and blue sub-pixel areas. This local structural uniformity ensures that the cell gap is consistent across all sub-pixel types, thereby maintaining uniform light efficiency and preventing the uneven light distribution that would result from varying thicknesses.
3Shape
If the dummy color filter layer thickness is reduced to minimize step difference, then flatness is improved, but light transmittance may be affected
Solution Approach 1:
The patent applies parameter changes by optimizing the thickness of the dummy color filter layer to match the thickness of the color filter layers in red, green, and blue sub-pixel areas. This parameter optimization ensures that the step difference is minimized (improving flatness) while maintaining sufficient light transmittance, as the dummy layer's thickness is carefully controlled to be equivalent to functional color filter layers rather than arbitrarily reduced.
Data Source
AI summary
A display panel includes: a substrate including red, green, blue and white sub-pixel areas; red, green and blue color filter layers respectively in the red, green and blue sub-pixel areas; and a dummy color filter layer in the white sub-pixel area. The dummy color filter layer is adjacent to at least one of the red color filter layer, the green color filter layer, and the blue color filter layer, and the dummy color filter layer forms a step with the adjacent color filter layer.