Backlight Wavelength Conversion Layer for LCD Light Loss Reduction
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Solution Overview
Problem
Color liquid crystal displays (LCDs) face inefficiencies in light emission due to multiple layers and air interfaces in their backlights, leading to reduced efficacy and increased costs, particularly in larger devices like TVs and monitors.
Innovation Solution
Incorporating a photoluminescence wavelength conversion layer with a mixture of green- and red-emitting materials and light scattering particles, which eliminates the need for separate diffusive layers and reduces light losses by minimizing air interfaces, thereby enhancing light uniformity and generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If multiple separate layers are used in the backlight structure, then light diffusion and wavelength conversion functions can be achieved, but light losses at air interfaces increase and display efficacy decreases
Solution Approach 1:
The patent combines the wavelength conversion layer and light diffusion layer into a single integrated photoluminescence layer. This layer contains both photoluminescence materials (for wavelength conversion) and light scattering particles (for diffusion), eliminating the need for separate layers and reducing air interfaces that cause light loss.
Solution Approach 2:
The photoluminescence layer uses composite materials by mixing photoluminescence materials with light scattering particles in a single layer structure. This composite approach enables simultaneous wavelength conversion and light diffusion functions while maintaining optical efficiency.
2Ease of manufacture
If photoluminescence materials are used in sufficient quantities to generate required light output, then display brightness is maintained, but manufacturing cost increases
Solution Approach 1:
Light scattering particles act as intermediaries that enhance the interaction between incident light and photoluminescence materials. By scattering light multiple times within the layer, these particles increase the probability of photon absorption by photoluminescence materials, thereby improving light generation efficiency and reducing the required quantity of expensive photoluminescence materials.
Solution Approach 2:
The patent changes the optical parameters of the layer by introducing light scattering particles, which modify the light path and increase the effective interaction length between light and photoluminescence materials. This parameter change enhances light generation efficiency without requiring additional photoluminescence material.
3Productivity
If light scattering material particles are added to the photoluminescence layer, then light uniformity and generation increase, but the layer composition becomes more complex
Solution Approach 1:
The photoluminescence layer is designed to perform multiple functions simultaneously: wavelength conversion (via photoluminescence materials), light diffusion (via light scattering particles), and light uniformity enhancement. This multi-functional design consolidates what would otherwise require separate layers into a single universal layer.
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 increases light emission by up to 40% and reduces the quantity of photoluminescence materials required, resulting in lower manufacturing costs and improved display efficacy while maintaining high color gamut.
Implementation Method 1
a photoluminescence wavelength conversion layer which when excited by excitation light, typically blue light, generates white light for operating the display
Implementation Method 2
The inclusion of particles of a light scattering material can increase uniformity of light emission from the photoluminescence wavelength conversion layer
Data Source
AI summary
A display backlight, comprises: an excitation source, LED (146), for generating blue excitation light (148) with a peak emission wavelength in a wavelength range 445 nm to 465 nm; and a photoluminescence wavelength conversion layer (152). The photoluminescence wavelength conversion layer (152) comprises a mixture of a green-emitting photoluminescence material with a peak emission in a wavelength range 530 nm to 545 nm, a red-emitting photoluminescence material with a peak emission in a wavelength range 600 nm to 650 nm and particles of light scattering material.