Color Filter Substrate Planarization Without Overcoat Layer
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Solution Overview
Problem
Conventional color filter substrates without an overcoat layer suffer from display defects such as halftone display blur, contrast decline due to light leaks, and vibration spots caused by uneven surface flatness and steep steps, which hinder high-resolution and cost-effective production.
Innovation Solution
A color filter substrate design that includes a black matrix pattern and color layer pattern on a transparent substrate, with a planarization pattern layer covering the outer step portion of the frame pattern, eliminating the need for an overcoat layer and using materials like photosensitive acrylic resin for the planarization layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an overcoat layer is removed to reduce process steps and material cost, then manufacturing complexity and cost are reduced, but surface flatness deteriorates causing display defects such as halftone blur, contrast decline, and vibration spots
Solution Approach 1:
The patent applies local quality by creating a planarization pattern layer with varying thickness - thicker at the outer peripheral portion of the black matrix frame and thinner toward the display area. This localized thickness variation compensates for the steep steps at the frame periphery without affecting the flatness of the display area, thereby eliminating vibration spots and halftone blur while maintaining the non-overcoat structure
Solution Approach 2:
The planarization pattern layer is formed beforehand to preemptively compensate for surface irregularities caused by the black matrix frame's outer peripheral portion. By pre-leveling the surface before subsequent processing steps, the invention prevents display defects without requiring an overcoat layer, thus reducing manufacturing complexity while maintaining surface precision
2Manufacturing precision
If the outer peripheral portion of the black matrix frame is left with steep steps to maintain high-definition in the display area, then pattern definition is improved, but surface uniformity deteriorates causing light leaks and contrast decline
Solution Approach 1:
The planarization pattern layer provides localized surface uniformity at the outer peripheral portion of the black matrix frame without interfering with the pattern definition in the display area. The layer's thickness is specifically controlled to be thicker at the frame periphery where planarization is needed and thinner in the display area where high-definition patterning must be maintained
Solution Approach 2:
The invention segments the surface treatment into two distinct zones: the display area requiring high-definition patterning and the outer peripheral portion requiring planarization. The planarization pattern layer is strategically positioned to affect only the frame periphery, leaving the display area's pattern definition intact while correcting surface uniformity issues
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 design improves display quality by reducing steep steps and litter-related defects, maintaining high-definition and cost-effectiveness without adding new processes or materials, enhancing surface uniformity and contrast while preventing vibration spots.
Implementation Method 1
using materials like photosensitive acrylic resin for the planarization layer
Data Source
AI summary
In a color filter substrate without an overcoat layer, a planarization pattern layer is further provided so as to cover at least an outer step portion of a frame-shaped resin black matrix.