Sunlight Readable LCD with In-Cell Retarder
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Transmissive and emissive displays struggle to reduce uncontrolled ambient light reflections in high ambient illumination conditions, particularly in LCDs using Fringe-Field Switching (FFS) mode, which affects image quality and contrast ratio, and existing methods to address this add cost and manufacturing complexity.
Innovation Solution
Incorporating a combination of external and internal quarter wave plate (QWP) retarder layers to convert circularly polarized light back to a linear state before it enters the liquid crystal material, thereby absorbing unwanted reflections and maintaining high-quality transmissive display performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If FFS LCD uses standard linear polarisers for high dark room contrast, then dark room image quality is improved, but sunlight readability deteriorates due to uncontrolled ambient light reflections
Solution Approach 1:
A circular polariser is introduced as an intermediary component between the linear polariser and the viewer. This circular polariser converts linearly polarised light from the linear polariser into circularly polarised light, which then interacts with the FFS LCD's liquid crystal layer to achieve both high dark room contrast and reduced ambient light reflections. The circular polarisation state acts as a mediator that enables the system to simultaneously achieve both performance requirements that are mutually exclusive with standard linear polarisers alone.
2Object-affected harmful factors
If FFS LCD incorporates circular polariser for reduced reflections, then sunlight readability is improved, but dark room contrast deteriorates due to LC director orientation blocking black state
Solution Approach 1:
The polarisation control function is segmented into two separate components: a linear polariser that provides the primary polarisation for high contrast performance, and a circular polariser that handles the reflection reduction function. This segmentation allows each component to optimise for its specific function without compromising the other, resolving the contradiction between reflection reduction and dark room contrast maintenance.
Solution Approach 2:
The invention changes the polarisation state parameter from linear to circular by introducing the circular polariser. This parameter change enables the system to achieve both high dark room contrast (through the linear polariser's controlled polarisation) and reduced ambient light reflections (through the circular polariser's ability to absorb reflected light). The parameter transformation resolves the contradiction by operating in a different polarisation regime.
3Object-affected harmful factors
If additional spatially patterned layers are added to FFS display for controlled reflection, then sunlight readability is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The circular polariser serves multiple functions simultaneously: it converts linearly polarised light to circularly polarised light for proper FFS operation, absorbs ambient light reflections to improve sunlight readability, and maintains compatibility with the existing FFS LCD structure. This multi-functionality eliminates the need for additional spatially patterned layers, reducing manufacturing complexity while achieving the desired reflection control.
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 solution effectively reduces uncontrolled ambient light reflections, improving image quality and contrast ratio in high ambient lighting conditions without increasing cost or complexity, while maintaining dark room performance.
Implementation Method 1
Incorporating a combination of external and internal quarter wave plate (QWP) retarder layers to convert circularly polarized light back to a linear state
Implementation Method 2
a circular front polariser to absorb reflection of ambient light from within the display
Data Source
AI summary
A display device in which ambient light reflections, for example, from IPS or FFS type displays are reduced by a circular polariser (e.g., linear polariser combined with external quarter waveplate) to make the light circular polarized, as it traverses the multiple reflective layers between the polariser and LC layer, and then an internal quarter waveplate converts the light back to linear polarisation before it enters the LC, so the display can operate as normal, while the circular polariser absorbs unwanted reflections of ambient light from within the display.