Blue Light Filtration Layer for OLED Color and Circadian Control
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Solution Overview
Problem
Existing blue light filtration systems are less effective in reducing the impact of blue light emitted by OLED displays, which have longer wavelength peaks, and also fail to adequately address the impact on circadian rhythms.
Innovation Solution
A blue light filtration film or layer comprising multiple absorbing compounds with specific peak absorptions and full-width half maxima, designed to minimize the transmission of longer wavelength blue light while maintaining the correlated color temperature and white point of the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional blue light filtration systems are used, then short wavelength blue light (435-440 nm) is filtered, but longer wavelength blue light from OLED displays (460-490 nm) is not effectively reduced
Solution Approach 1:
The patent changes the absorption parameters of the filtering compounds to match the emission spectrum of OLED displays. Specifically, it uses compounds with peak absorptions at 477-505 nm, 575-600 nm, and 672-705 nm, which are optimized for the longer wavelength blue light emitted by OLEDs (460-490 nm), rather than the shorter wavelength blue light from LED displays.
Solution Approach 2:
The patent employs a composite filtering layer containing three different absorbing compounds with distinct absorption spectra. This composite approach allows simultaneous targeting of multiple wavelength regions (blue, cyan, and red portions of the spectrum) to comprehensively address the OLED emission spectrum while maintaining display quality.
2Object-affected harmful factors
If broader spectrum filtration is applied to reduce circadian impact, then more blue and cyan light is blocked, but display color accuracy and white point are degraded
Solution Approach 1:
The patent applies local quality by using three distinct absorbing compounds, each with a specific peak absorption wavelength and narrow full-width half maximum (30-50 nm). This allows targeted filtration at specific wavelength regions (blue, cyan, red) while preserving transmission in other regions, thereby maintaining overall display color accuracy and white point.
Solution Approach 2:
The patent carefully controls the absorption parameters (peak wavelength and full-width half maximum) of each compound to achieve selective filtration. By tuning these parameters, the system reduces circadian impact through broader spectrum blocking while minimizing unwanted effects on display color temperature and white point.
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 filtration system effectively reduces both Blue Light Hazard and circadian disruption for OLED displays by absorbing light across a broader spectrum, ensuring minimal impact on the display's color and luminance.
Implementation Method 1
The first absorbing compound can absorb light in a notch band having a full-width half maximum of no more than 40 nm. The second absorbing compound can absorb light in a notch band having a full-width half maximum of no more than 40 nm. The third absorbing compound can absorb light in a notch band having a full-width half maximum of no more than 40 nm.
Data Source
AI summary
A light-filtering layer is provided that comprises a polymer substrate and at least three absorbing compounds combined with the polymer substrate, wherein the absorbing compounds each absorb light in a notch band having a full-width half maximum of no more than 40 nm. In some examples, the absorbing compounds can be provided in combination so that, for light produced by a display screen that is transmitted through the light-filtering layer, the correlated color temperature is within 1000 Kelvin of the correlated color temperature for light produced by the display screen that is not transmitted through the light-filtering layer. Peak absorptions for the first, second, and third absorbing compounds can be between 436 nm and 522 nm, 548 nm and 616 nm, and 643 nm and 730 nm, respectively. In some embodiments, a fourth absorbing compound can be provided in combination with the polymer substrate and absorbing compounds and can have peak absorption between 417 nm and 465 nm.