Liquid Crystal Display Antireflection Layer for Contrast Ratio
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Solution Overview
Problem
In liquid crystal display devices of the 'Color filter On Array' (COA) type, the degradation of the contrast ratio is a concern due to external light reflection on metal lines, which affects display quality.
Innovation Solution
A liquid crystal display device configuration that includes a first substrate with scanning signal lines, video signal lines, a color filter, an antireflection layer, and a transparent layer of specific thickness to minimize reflection, along with a second substrate with a light-shielding layer, optimizing the structure to suppress reflection and maintain a high contrast ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If color filters and metal lines are disposed on one substrate without light-shielding layer on the other substrate to improve aperture ratio, then aperture ratio is improved, but contrast ratio deteriorates due to external light reflection on metal lines
Solution Approach 1:
A transparent layer with specific refractive index (1.3-1.7) and thickness (50-200 nm) is introduced as an intermediary between the metal lines and the external environment. This layer acts as a mediator that reduces the reflection of external light on the metal lines through refractive index matching, thereby suppressing contrast ratio degradation while maintaining the aperture ratio improvement from the COA structure
Solution Approach 2:
The refractive index and thickness of the transparent layer are optimized as key parameters to control light reflection. By adjusting the refractive index to match between 1.3-1.7 and thickness to 50-200 nm, the reflection characteristics are modified to minimize harmful reflections on metal lines while preserving the aperture ratio benefits
2Object-affected harmful factors
If antireflection layer and transparent layer are added to suppress reflection on metal lines, then contrast ratio is improved, but device complexity increases
Solution Approach 1:
The transparent layer serves multiple functions simultaneously: it acts as an antireflection coating to suppress reflections on metal lines, provides structural protection to the underlying layers, and maintains optical transparency. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in device complexity while achieving reflection suppression
Solution Approach 2:
The patent employs composite material structures combining the transparent layer with the antireflection layer and existing substrate materials. This composite approach allows optimized optical properties through material combination rather than requiring complex single-layer solutions, balancing reflection suppression performance with structural simplicity
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
The proposed configuration effectively reduces reflection and maintains a high contrast ratio, thereby enhancing the display quality by ensuring minimal impact from external light and improving the aperture ratio.
Implementation Method 1
a transparent layer located on the antireflection layer, the transparent layer having a thickness of 10 nm or more and 40 nm or less
Data Source
AI summary
According to one embodiment, a liquid crystal display device, includes a first substrate including a scanning signal line, a video signal line, a first electrode, a color filter, a common line in contact with the first electrode along the video signal line, an antireflection layer located on the common line, a transparent layer located on the antireflection layer, and a second electrode, a liquid crystal layer located on the first substrate, and a second substrate located on the liquid crystal layer, the transparent layer having a thickness of 10 nm or more and 40 nm or less.