Quantum Rod Sheet for LCD Light Efficiency
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Solution Overview
Problem
LCD devices suffer from low light efficiency due to incomplete polarization of light from the backlight, resulting in reduced transmissivity and brightness, as non-polarized light is scattered by pigments in the color filter layer, converting it into elliptically-polarized light that cannot pass through the second polarization plate.
Innovation Solution
Incorporating a quantum rod sheet between the liquid crystal panel and the second polarization plate, where quantum rods are aligned parallel to the transmission axis of the second polarization plate, absorbing and re-polarizing elliptically-polarized light to enhance light transmissivity and brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional LCD structure with polarization plates is used, then the device achieves basic light transmission function, but light efficiency is low due to scattering by pigments converting linearly-polarized light into elliptically-polarized light
Solution Approach 1:
A quantum rod sheet is introduced as an intermediary component between the liquid crystal panel and the second polarization plate. This quantum rod sheet acts as a mediator that converts elliptically-polarized light back into linearly-polarized light, enabling the light to pass through the second polarization plate effectively. The quantum rods absorb elliptically-polarized light and re-emit linearly-polarized light aligned with the transmission axis of the second polarization plate, thereby resolving the light efficiency problem without fundamentally changing the overall LCD structure.
Solution Approach 2:
The invention changes the polarization state parameter of light by using quantum rods with specific optical properties. The quantum rods are oriented with their long axes parallel to the transmission axis of the second polarization plate, and they convert elliptically-polarized light into linearly-polarized light through their anisotropic absorption and emission characteristics. This parameter change in light polarization state enables improved light transmission through the polarization plate.
2Illumination intensity
If the second polarization plate is oriented perpendicular to the first polarization plate, then the LCD achieves basic display function, but transmissivity is reduced because elliptically-polarized light cannot pass through
Solution Approach 1:
The quantum rod sheet serves as a mediator that transforms the polarization state of light before it reaches the second polarization plate. By converting elliptically-polarized light into linearly-polarized light with the transmission axis parallel to the second polarization plate, the quantum rod sheet ensures that maximum light can pass through, thereby improving both brightness and transmissivity simultaneously.
Solution Approach 2:
The invention converts the harmful effect of pigment scattering that creates elliptically-polarized light (which cannot pass through the second polarization plate) into a beneficial effect. The quantum rod sheet utilizes this elliptically-polarized light as input and converts it into useful linearly-polarized light that can pass through the second polarization plate, thereby turning the scattering problem into a solution that enhances light transmission.
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 quantum rod sheet improves brightness by 0.9 to 9% compared to traditional LCD devices, while reducing power consumption, by effectively re-polarizing elliptically-polarized light and maintaining high internal quantum yield.
Implementation Method 1
quantum rods are aligned parallel to the transmission axis of the second polarization plate, absorbing and re-polarizing elliptically-polarized light
Implementation Method 2
quantum rods are aligned parallel to the transmission axis of the second polarization plate, absorbing and re-polarizing elliptically-polarized light
Data Source
AI summary
A liquid crystal display (LCD) device includes a first substrate; a second substrate; a liquid crystal layer disposed between the first and second substrates; a color filter on one of the first and second substrates; a first polarization plate under the first substrate; a second polarization plate over the second substrate; a backlight unit under the first polarization plate; and a quantum rod sheet disposed between the color filter and the second polarization plate.