Variable Thickness Light Blocking Member for LCD Aperture Ratio
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Solution Overview
Problem
In liquid crystal displays (LCDs), alignment errors between pixel electrodes and color filters lead to image quality defects, and the increased size of light blocking members to address these issues results in decreased aperture ratio and challenges in maintaining uniform cell gaps, causing gap defects and torn patterns.
Innovation Solution
The implementation of a light blocking member with varying thicknesses in different dead space areas adjacent to the display area, using an optical mask with halftone and full-tone regions to prevent light leakage and gap defects, and employing a dummy color pattern as a lower support layer to reduce step height and critical dimension variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the light blocking member is increased in size to prevent alignment errors between pixel electrodes and color filters, then light leakage is prevented, but the aperture ratio is decreased
Solution Approach 1:
The light blocking member is designed with different thicknesses in different regions: a first thickness in the first dead space area adjacent to the display area, and a second thickness (greater than the first) in the second dead space area. This local differentiation allows optimized light blocking performance without uniformly increasing the aperture ratio across the entire display.
Solution Approach 2:
The invention changes the thickness parameter of the light blocking member across different regions. By using an optical mask with halftone and full-tone regions, the light blocking member achieves variable thickness, thereby optimizing both light leakage prevention and aperture ratio maintenance through parameter variation rather than uniform design.
2Object-affected harmful factors
If the light blocking member is increased in size to address alignment errors, then light leakage is prevented, but gap defects and torn patterns occur in the outermost cell
Solution Approach 1:
The light blocking member employs different thicknesses in different dead space areas to locally optimize performance. The first thickness in the first dead space area prevents excessive light blocking that causes gap defects, while the second thickness in the second dead space area ensures adequate light blocking to prevent light leakage, thus resolving the reliability issue.
Solution Approach 2:
The non-display area is segmented into multiple dead space areas (first, second, third), and the light blocking member is correspondingly divided into segments with different thicknesses. This segmentation allows each region to be optimized independently, preventing both gap defects and light leakage simultaneously.
3Ease of manufacture
If a multi-step process is implemented to simultaneously form the light blocking member and spacers, then manufacturing complexity increases, but multi-transmittance mask and material limitations remain
Solution Approach 1:
The invention combines the formation of the light blocking member and spacers into a single coating and exposure process. By using an optical mask with both halftone and full-tone regions, both structures are formed simultaneously from a single material layer, merging two manufacturing steps into one and avoiding the need for separate processes.
Solution Approach 2:
The optical mask with halftone and full-tone regions serves multiple functions: it defines both the light blocking member pattern and the spacer pattern in a single exposure step. This multi-functional mask design eliminates the need for separate masks and processes for forming different structures.
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 effectively prevents light leakage, reduces the possibility of gap defects and torn patterns, maintains uniform critical dimensions, and enhances the aperture ratio by accurately aligning light blocking members and color filters, ensuring consistent image quality across the LCD.
Implementation Method 1
forming first to third light blocking members through exposure by using an optical mask in which at least two or more halftone regions and a full-tone region are mixed
Data Source
AI summary
A manufacturing method of a liquid crystal display includes forming display pixels which display an image and dummy pixels which do not display the image on a lower substrate including a display area and a non-display area positioned in at least one side outside the display area, coating a light blocking member material layer on a first dead space area adjacent to the display area and having a dummy area where the dummy pixels are positioned, a second dead space area adjacent to the first dead space area, and a third dead space area adjacent to the second dead space area in the non-display area, and forming first to third light blocking members through exposure by using an optical mask in which at least two or more halftone regions and a full-tone region are mixed.