Overlapping Subpixel Electrodes for LCD Transmittance
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Solution Overview
Problem
Liquid crystal displays (LCDs) in vertical alignment mode face challenges in achieving accurate gray expression at low gray levels and maintaining transmittance, especially when approximating side visibility to front visibility, as dividing one pixel into subpixels can lead to increased luminance and decreased transmittance.
Innovation Solution
A liquid crystal display design featuring first and second subpixel electrodes on a substrate with an insulating layer in between, where portions of the electrodes overlap, and a common electrode on a second substrate, allowing for different voltages to be applied to create distinct regions within a pixel for improved gray expression and reduced transmittance deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If one pixel is divided into two subpixels with different transmittances to approximate side visibility to front visibility, then side viewing angle is improved, but luminance increases at low gray/high gray levels making gray expression difficult
Solution Approach 1:
The pixel is divided into two subpixels with different transmittances, where the first subpixel has higher transmittance and the second subpixel has lower transmittance. This segmentation allows different regions to contribute differently to the overall luminance, enabling accurate gray expression while maintaining good side viewing angle characteristics.
Solution Approach 2:
Different regions within the pixel are assigned different transmittance properties. The first subpixel region has higher transmittance while the second subpixel region has lower transmittance, creating local quality variations that enable precise control of gray levels and improve viewing angle without compromising gray expression accuracy.
2Adaptability or versatility
If one pixel is divided into two subpixels, then viewing angle characteristics are improved, but transmittance decreases according to the interval between subpixels
Solution Approach 1:
The first and second subpixels are positioned to overlap with each other, merging their light transmission paths. This overlapping configuration reduces the effective interval between subpixels, minimizing light loss and maintaining high overall transmittance while still achieving the desired viewing angle improvement through differential transmittance control.
Solution Approach 2:
The subpixels are arranged in an overlapping configuration rather than simple side-by-side positioning. This spatial arrangement in multiple dimensions reduces the effective gap between subpixels, thereby minimizing transmittance loss while preserving the viewing angle benefits of having distinct subpixel regions with different transmittances.
3Manufacturing precision
If different voltages are applied to subpixels to control luminance, then gray expression is improved, but transmittance deteriorates
Solution Approach 1:
The first subpixel is designed with inherently higher transmittance properties, requiring less voltage control effort to achieve desired luminance levels. The second subpixel has lower transmittance and requires different voltage control. This partial differentiation in transmittance design reduces the overall voltage control burden while maintaining accurate gray expression capability.
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 enables more accurate gray representation in low gray regions while maintaining side visibility similar to front visibility, and prevents transmittance deterioration by dividing the pixel into regions with varying luminance, resulting in smoother transmittance changes across gray shades.
Implementation Method 1
The liquid crystal display generates an electric field in the liquid crystal layer by applying a voltage to the field generating electrodes
Implementation Method 2
determines the orientation of liquid crystal molecules of the liquid crystal layer by the generated electric field, thus controlling polarization of incident light
Implementation Method 3
an insulating layer positioned between the first subpixel electrode and the second subpixel electrode
Data Source
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AI summary
A liquid crystal display according to an exemplary embodiment of the present invention includes: a first substrate (110); a first subpixel electrode (191a) positioned on the first substrate (110) and configured to receive a first voltage; a second subpixel electrode (191b) positioned on the first substrate (110) and configured to receive a second voltage; an insulating layer (180b) positioned between the first subpixel electrode (119a) and the second subpixel electrode (191b); a second substrate (210) facing the first substrate (110); and a common electrode (270) positioned on the second substrate (210) and configured to receive a common voltage. A portion of the first subpixel electrode (191a) and a portion (194a) of the second subpixel electrode (191b) overlap each other with the insulating layer (180b) interposed therebetween, and the difference between the first voltage and the common voltage is larger than the difference between the second voltage and the common voltage.