Optical Polarizer Stack for Uniform Display Block-State Transmittance
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Solution Overview
Problem
Conventional absorbing polarizers exhibit high spatial variation in block state transmittance and polarization efficiency, leading to optical defects in displays.
Innovation Solution
Combining a high contrast reflective polarizer with a weaker absorbing polarizer, such as a thinner polyvinyl alcohol layer with reduced iodine concentration, to form an optical stack that minimizes spatial variation and enhances transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional absorbing polarizer is used, then the display achieves polarization function, but high spatial variation in block state transmittance and polarization efficiency occurs, leading to optical defects
Solution Approach 1:
The patent combines a reflective polarizer and an absorbing polarizer into a composite optical stack. The reflective polarizer (with high polarization efficiency >0.995 and low standard deviation <0.001) compensates for the spatial variations in the absorbing polarizer, eliminating optical defects while maintaining the polarization function.
2Illumination intensity
If a high contrast reflective polarizer is combined with a weaker absorbing polarizer, then brightness and efficiency are improved, but the complexity of the optical system increases
Solution Approach 1:
The optical system is segmented into two functional modules: a reflective polarizer layer and an absorbing polarizer layer. Each layer has optimized thickness and material properties (reflective polarizer withTd>0.85 and Tb<0.001, absorbing polarizer with average transmittance >0.46), allowing independent optimization while reducing overall system complexity through functional division.
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 combination results in higher brightness and improved efficiency in displays without significant drops in contrast ratio, reducing optical defects and enhancing overall performance.
Implementation Method 1
each interference layer reflects or transmits light primarily by optical interference
Implementation Method 2
an optical absorption greater than about 50% for the second polarization state
Data Source
AI summary
An optical stack includes a reflective polarizer including a plurality of interference layers and an absorbing polarizer disposed on the reflective polarizer. The plurality of interference layers transmits at least about 85% of an incident light having a first polarization state, reflects at least about 80% of the incident light having a second polarization state, and transmits less than about 0.1% of the incident light having the second polarization state. The absorbing polarizer has a first transmittance for the first polarization state and a second transmittance for the second polarization state. An average of the first and second transmittances is greater than about 0.46. The second transmittance has a first standard deviation. The optical stack has a transmittance for the second polarization state having a second standard deviation which is less than the first standard deviation by at least about 10%. A display includes the optical stack.