Quantum Rod Backlight Module Polarization and Light Utilization
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Solution Overview
Problem
Conventional liquid crystal display backlight modules suffer from low light utilization and inadequate color gamut due to absorptive polarizers, with existing brightness enhancement techniques improving luminance but not significantly affecting gamut or color saturation, and quantum rod layers' dichroism is compromised by material retardation differences and prism layer arrangements.
Innovation Solution
A quantum rod backlight module is designed with a quantum rod layer aligned parallel to the surface, accompanied by micro-prism layers with zero retardation and specific refractive indices, and materials like polymethyl methacrylate and polyethylene terephthalate, where the micro-prism layers' prisms are perpendicular to the quantum rods' major axes to maintain polarization directionality and enhance light transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If absorptive polarizers are used in the liquid crystal display, then the polarization function is achieved, but the light utilization is reduced by at least 50%
Solution Approach 1:
The patent replaces absorptive polarizers with a quantum rod layer that generates polarized light through photoluminescence. The quantum rods absorb non-polarized light and emit polarized light with a specific orientation, eliminating the need for absorptive polarizers and reducing light loss from 50% to minimal levels while maintaining the polarization function required for LCD operation.
Solution Approach 2:
The patent changes the fundamental mechanism of polarization from absorption to generation. By using quantum rods with specific optical properties (absorbing non-polarized light and emitting polarized light), the system transforms the polarization parameter from a filtering process to an active generation process, thereby improving light utilization while maintaining polarization functionality.
2Ease of operation
If conventional optical films with retardation are used in the backlight module, then the light guidance function is achieved, but the dichroic ratio of the quantum rod layer is reduced
Solution Approach 1:
The patent removes conventional optical films with retardation properties from the backlight module and replaces them with zero-retardation optical films. This extraction eliminates the harmful retardation effect that reduces the dichroic ratio, while the light guidance function is maintained through alternative optical design of the zero-retardation films and micro-prism structures.
Solution Approach 2:
The patent changes the retardation parameter of the optical films from non-zero to zero. By using zero-retardation optical films, the system eliminates the parameter that causes dichroic ratio reduction while maintaining the necessary light guidance and distribution functions through optimized optical path design and micro-prism geometry.
3Illumination intensity
If quantum dots are used to increase the gamut, then the color saturation is improved, but the light utilization remains lower compared to quantum rods
Solution Approach 1:
The patent inverts the conventional approach by using quantum rods instead of quantum dots. While quantum dots convert light wavelengths, quantum rods generate polarized light directly from non-polarized light through photoluminescence. This inversion of the light conversion mechanism achieves both high color gamut and high light utilization simultaneously, as the quantum rods emit polarized light that can be efficiently used by the LCD without the 50% loss from absorptive polarizers.
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 light utilization and maintains polarization directionality, resulting in a higher dichroic ratio and better brightness enhancement, particularly when light passes through the polarizer, enhancing the color gamut and overall display performance.
Implementation Method 1
The quantum rod is able to absorb the non-polarized light to emit a polarized light with a wavelength longer than the original non-polarized light from the major axis direction
Implementation Method 2
reflective brightness enhancement film (e.g., Dual Brightness Enhancement Film, DBEF), prism sheet and other optical film may be used in backlight module for continuously reflecting and reuse the light
Implementation Method 3
when the non-polarized light emitted from the backlight is incident onto the absorptive polarizers, a component of the incident light parallel to the absorption axis direction of the polarizers is absorbed
Data Source
AI summary
Disclosed herein is a quantum rod backlight module for a liquid crystal display. The quantum rod backlight module includes a quantum rod layer disposing at one side of a backlight source and comprising a plurality of quantum rods, wherein the major axes of the plurality of quantum rods are aligned along a direction parallel to a surface of the quantum rod layer; a first micro-prism layer including a plurality of first parallel strip-shape prisms, and a second micro-prism layer including a plurality of second parallel strip-shape prisms, wherein both of the alignment directions of the first parallel strip-shape prisms and the second parallel strip-shape prisms are perpendicular to the direction of the major axes of the plurality of quantum rods, and the retardations of the first micro-prism layer and the second micro-prism layer are zero.