Backlight Module Green Light Color Purity via Fabry-Perot Cavity
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Solution Overview
Problem
Conventional LCD backlight modules face challenges in achieving high color purity and gamut, particularly in the green color spectrum, which is exacerbated by the limitations of quantum dot technology in terms of efficiency and spectrum distribution.
Innovation Solution
A backlight module design featuring a light-guiding plate with a blue light source, red and green quantum dot films, and metal wire grids arranged to form a Fabry-Perot cavity, which selectively enhances the luminance intensity of specific green wavelengths, improving color purity and gamut by resonant excitation and Purcell effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If quantum dot films are used to convert blue light to green light, then color gamut is improved, but the efficiency and luminance intensity of green light emission remain insufficient
Solution Approach 1:
The patent changes the optical parameters of the system by introducing metal wire grids with specific periodic structures that resonate at the green light wavelength. This resonant structure modifies the electromagnetic field distribution, enhancing the green light emission efficiency of the quantum dot film without changing the quantum dot material itself, thereby resolving the contradiction between color gamut improvement and emission efficiency
Solution Approach 2:
The patent creates a composite structure combining quantum dot films with metal wire grids forming a Fabry-Perot cavity. This composite system leverages the quantum confinement effect of quantum dots for color purity and the resonant enhancement of the metal-dielectric-metad structure for efficiency improvement, achieving both high color gamut and high green light luminance intensity
2Ease of manufacture
If conventional broadband green phosphors are used, then manufacturing is simpler, but color purity and gamut are reduced
Solution Approach 1:
The patent uses metal wire grids with precisely controlled periodic parameters (distance d = m × λ₀/2) to resonate at the peak wavelength of green light emission. This parameter-controlled approach maintains the simplicity of quantum dot film deposition while achieving narrow spectral width and high color purity, resolving the contradiction between manufacturing simplicity and color purity
3Device complexity
If the backlight module structure is simplified, then device complexity is reduced, but the ability to enhance green light luminance is insufficient
Solution Approach 1:
The patent replaces traditional complex brightness enhancement structures (such as microlens arrays or complex reflective layers) with a metal wire grid structure that utilizes optical resonance and the Purcell effect. This substitution achieves high green light luminance enhancement through electromagnetic field manipulation rather than complex mechanical optical paths, reducing device complexity while maintaining high illumination intensity
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 significantly enhances the color purity and luminance intensity of green light, increasing the color gamut and addressing the low efficiency issues of quantum dot films, while also potentially reducing module thickness through integrated brightness enhancement.
Implementation Method 1
two metal wire grids disposed respectively on both sides of the green QD film; the distance between the two metal wire grids disposed on both sides of the green QD film being a multiple of a specific green light wavelength
Implementation Method 2
selectively enhances the luminance intensity of specific green wavelengths, improving color purity and gamut by resonant excitation
Implementation Method 3
a blue light source disposed on one side of the light-guiding plate, and a red light conversion layer and a green light conversion layer stacked and disposed above the light-exiting side of the light-guiding plate; the red light conversion layer comprising a red quantum dot (QD) film; the green light conversion layer comprising a green QD film
Implementation Method 4
improving color purity and gamut by resonant excitation and Purcell effect
Data Source
AI summary
The invention provides a backlight module, using blue backlight to excite the red, green QD films to obtain red and green fluorescence; and disposing two metal wire grids on both sides of the green QD film to form a Fabry-Perot cavity, the Fabry-Perot cavity able to select and enhance luminance intensity of a specific wavelength selected from the green light emitted by the green QD film so as to improve color purity and luminous intensity of the green light, and thus increase the color gamut of the backlight module, as well as improve the luminous efficiency of the green QD film, and significantly improve the low efficiency problem of fluorescence QD film. Moreover, the metal wire grid may form a brightness enhancing structure with the reflective layer of the backlight module to save setting up a brightness enhancing structure and reduce the thickness of the backlight module.