Reflective Polarizer Bands for OLED Color Accuracy and Low Ghosting
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Solution Overview
Problem
Existing OLED displays face challenges in maintaining color accuracy and brightness while reducing ambient light reflection, particularly at off-normal viewing angles, due to inadequate polarizer designs that cause ghosting and color shifts.
Innovation Solution
A reflective polarizer with distinct blue, green, and red-infrared reflection bands, including absorption peaks between the green and red wavelengths, is integrated into the display system to enhance color gamut and reduce ghosting by optimizing light recycling and maintaining color consistency across viewing angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a circular polarizer is used to reduce ambient light reflection, then reflection is reduced, but color accuracy and brightness are compromised particularly at off-normal viewing angles
Solution Approach 1:
The polarizer is segmented into multiple distinct reflection bands (blue, green, and red-infrared) with specific wavelength ranges. Each band targets specific ambient light wavelengths while preserving display emission wavelengths, allowing selective reflection reduction without compromising color accuracy across different viewing angles
Solution Approach 2:
The reflective polarizer has different optical properties at different wavelengths and viewing angles. The reflection bands are designed with specific characteristics: blue reflection band (400-500nm) with 60% reflectance, green reflection band (500-600nm) with 60% reflectance, and red-infrared reflection band (600-1000nm) with 40% reflectance, optimizing performance for each wavelength region while maintaining color accuracy
2Object-affected harmful factors
If a circular polarizer is used to reduce ambient light reflection, then reflection is reduced, but brightness is compromised particularly at off-normal viewing angles
Solution Approach 1:
The polarizer segments the spectrum into reflection bands and transmission bands. The display emission wavelengths fall within transmission bands where the polarizer allows high light throughput, while ambient light wavelengths fall within reflection bands. This segmentation ensures brightness is maintained for display content while ambient light reflection is reduced
Solution Approach 2:
The reflective polarizer parameters are optimized to change reflectance behavior with viewing angle. For the first polarization state, reflectance decreases for blue and green wavelengths at oblique angles, and increases or remains stable for red wavelengths, maintaining color consistency and brightness across different viewing angles
3Object-affected harmful factors
If a conventional polarizer is used, then ambient light reflection is reduced, but ghosting and color shifts occur at off-normal viewing angles
Solution Approach 1:
The polarizer is designed with locally optimized properties for different wavelength regions and viewing angles. Each reflection band (blue, green, red-infrared) has tailored reflectance characteristics that maintain color consistency. The absorption peak between green and red wavelengths further refines the spectral profile, ensuring stable color appearance across the viewing cone
Solution Approach 2:
The reflective polarizer parameters are specifically designed to change with viewing angle in a controlled manner. The reflectance for different wavelengths changes differently with angle, with blue and green reflectance decreasing and red reflectance increasing or remaining stable, which compensates for viewing angle effects and maintains color consistency
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 solution improves color gamut and reduces ghosting, maintaining color accuracy and brightness by enhancing light recycling and minimizing color shifts at various viewing angles, thereby improving the overall display performance.
Implementation Method 1
the reflective polarizer: reflects at least about 60% of the incident light for each of the blue and green peak wavelengths and at least about 40% of the incident light for the red peak wavelength for a first polarization state; transmits at least about 60% of the incident light for each of the blue, green and red peak wavelengths for an orthogonal second polarization state
Implementation Method 2
has an absorption peak at a wavelength between the green and red FWHMs of the respective green and red emission spectra
Implementation Method 3
the reflective polarizer has a reflection spectrum including substantially distinct blue, green and red-infrared reflection bands
Data Source
AI summary
A reflective polarizer has substantially distinct blue, green and red-infrared reflection bands for substantially normally incident light. A display system includes a display panel including blue, green and red light emitting pixels having respective blue, green and red peak wavelengths and respective blue, green and red FWHMs; and the reflective polarizer disposed on the light emitting pixels. The reflective polarizer: reflects at least about 60% of the incident light for each of the blue and green peak wavelengths and at least about 40% of the incident light for the red peak wavelength for a first polarization state; transmits at least about 60% of the incident light for each of the blue, green and red peak wavelengths for an orthogonal second polarization state; and has an absorption peak at a wavelength between the green and red FWHMs.