Sloped Transmission Front Reflector for LCD Backlight Light Recycling
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Solution Overview
Problem
Existing backlights, particularly direct-lit and edge-lit systems, face inefficiencies in light management due to the need for complex film stacks for spatial uniformity, light collimation, and polarization control, leading to suboptimal performance in LCD applications.
Innovation Solution
The implementation of a backlight system with a front and back reflector forming a light recycling cavity, utilizing apodized broadband partial reflectors with smooth and sloped transmission spectra, which enhances light recycling and collimation, and can be configured for edge-lit or direct-lit setups with high hemispherical reflectivity to improve output properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If complex film stacks are used for spatial uniformity, light collimation, and polarization control in existing backlights, then light management capability is improved, but system complexity and light loss increase
Solution Approach 1:
The patent extracts the light management functions from complex film stacks and consolidates them into a single front reflector with integrated optical properties. The front reflector is designed with specific reflectivity and transmission characteristics that simultaneously achieve spatial uniformity, collimation, and polarization control without requiring multiple separate films, thereby reducing system complexity while maintaining light management capability.
Solution Approach 2:
The front reflector is designed to perform multiple functions simultaneously: it provides spatial uniformity through its geometric configuration, achieves light collimation through its optical properties, and controls polarization through its material characteristics. This multi-functional design eliminates the need for separate film stacks for each function, reducing overall system complexity while maintaining comprehensive light management capability.
2Ease of operation
If complex film stacks are used for spatial uniformity, light collimation, and polarization control in existing backlights, then light management capability is improved, but light loss increases
Solution Approach 1:
The patent removes multiple light-transmitting film interfaces from the optical path and replaces them with a single front reflector design. This elimination of intermediate films reduces the number of reflection and refraction events where light is lost, while the front reflector's optimized optical properties maintain the necessary light management functions with higher overall transmission efficiency.
Solution Approach 2:
The front reflector is designed with specific optical parameters including reflectivity between 0.05 and 0.50, transmission characteristics, and geometric configuration that optimize light extraction while minimizing losses. By carefully controlling these parameters, the system achieves effective light management with reduced light loss compared to conventional multi-film approaches.
3Ease of manufacture
If conventional reflectors are used in backlight systems, then manufacturing simplicity is maintained, but light recycling efficiency and output properties are suboptimal
Solution Approach 1:
The front reflector is designed with optimized optical parameters including reflectivity between 0.05 and 0.50, specific transmission characteristics, and geometric configuration. These parameter optimizations enhance light recycling efficiency and output properties while remaining compatible with conventional manufacturing processes, thus improving productivity without sacrificing manufacturing simplicity.
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 configuration improves the efficiency and uniformity of light distribution, enhancing brightness and color accuracy across various viewing angles, particularly in LCD displays, while minimizing light loss and maintaining high reflectivity for both polarized and unpolarized light.
Implementation Method 1
a front broadband reflector with smooth and sloped transmission spectra
Implementation Method 2
The light guide uses total internal reflection (TIR) to transport or guide light
Implementation Method 3
The light guide uses total internal reflection (TIR) to transport or guide light from the edge-mounted lamps across the entire length or width of the light guide
Implementation Method 4
apodized broadband partial reflectors with smooth and sloped transmission spectra, which enhances light recycling and collimation
Implementation Method 5
smooth and sloped transmission spectra
Data Source
Figure 1~2
Figure 3
Figure 4a~4b
AI summary
A backlight (10) includes a front and back reflectors (12,14) forming a light recycling cavity (16) and one or more light source members (24a, 24b, 24c) disposed to emit light into the light recycling cavity. The front reflector (12) being partially reflective to provide an output illumination area. The front reflector (12) has a blue sloped transmission spectra, at normal incidence with a range among bin values from 15% to 100%.