Backlight Unit Filter for LCD Color Purity and Lifespan
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Solution Overview
Problem
Conventional liquid crystal display (LCD) backlight units using fluorescent lamps or LEDs face limitations in color purity and light efficiency due to wide full width half maximums of red and green light, leading to reduced color representation and a shortened lifespan of quantum dot members due to heat degradation.
Innovation Solution
A backlight unit incorporating a quantum dot member with a filter that transmits short wavelengths and reflects long wavelengths, optimizing temperature and improving color purity and light efficiency, and a liquid crystal display apparatus featuring this configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If quantum dot member is used as fluorescent body to improve color purity and light efficiency, then color representation is improved, but lifespan is reduced due to heat degradation
Solution Approach 1:
A reflector is introduced as an intermediary component between the quantum dot member and the backlight unit. The reflector reflects short-wavelength light (450-480nm) back toward the quantum dot member, enabling reuse of this light energy while isolating the quantum dot member from direct exposure to harmful short-wavelength radiation that causes degradation. This mediator approach allows the system to capture beneficial light for color enhancement while protecting the quantum dot member from damaging effects.
Solution Approach 2:
The optical path is segmented into different wavelength channels with selective handling. Short-wavelength light (450-480nm) is reflected back for reuse, medium-wavelength light (480-650nm) passes through for color representation, and long-wavelength light (>650nm) is blocked. This segmentation allows optimized management of different spectral components to simultaneously improve efficiency and protect the quantum dot member.
2Quantity of substance
If conventional fluorescent bodies are used with wide FWHM to provide broad spectrum light, then light coverage is improved, but color purity is reduced
Solution Approach 1:
Different regions of the optical system are assigned different functional properties. The reflector is designed with selective reflectivity for specific wavelength ranges (450-480nm), while the filter provides selective transmission for medium wavelengths (480-650nm) and blocking for long wavelengths (>650nm). This local quality differentiation allows the system to maintain broad spectrum coverage while achieving high color purity in the transmitted light.
Solution Approach 2:
The optical system utilizes wavelength-dependent parameter changes through the reflector and filter components. By changing the transmission and reflection characteristics based on wavelength, the system transforms the broad spectrum output into a filtered spectrum with enhanced color purity in the 480-650nm range while maintaining overall light quantity.
3Use of energy by moving object
If short wavelength light is used to excite quantum dot member for high efficiency, then light efficiency is improved, but heat generation increases causing degradation
Solution Approach 1:
The reflector converts what would be wasted short-wavelength light (450-480nm) into a beneficial resource by reflecting it back toward the quantum dot member. This reused light provides additional excitation energy without requiring additional input power, improving overall light efficiency. Simultaneously, the filter blocks harmful long-wavelength light (>650nm) that would contribute to heat generation, effectively converting potential harm into benefit.
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
Enhances color purity and light efficiency while extending the lifespan of the quantum dot member by effectively managing heat and improving color representation in LCDs.
Implementation Method 1
a filter disposed between the fluorescent member and the plurality of LEDs, and configured to selectively filter a first wavelength area of the tricolor light emitted from the fluorescent member toward the plurality of LEDs, and reflect a second wavelength area of the tricolor light emitted from the fluorescent member toward an output direction
Implementation Method 2
a filter disposed between the fluorescent member and the plurality of LEDs, and configured to selectively filter a first wavelength area of the tricolor light
Implementation Method 3
a fluorescent member configured to convert the blue light emitted from the plurality of LEDs into tricolor light and emit the tricolor light
Data Source
AI summary
A backlight unit (BLU) and a liquid crystal display apparatus having the BLU are provided. The BLU includes a plurality of light-emitting diodes (LEDs) configured to emit blue light, a fluorescent member configured to convert the blue light emitted from the plurality of LEDs into tricolor light and emit the tricolor light, and a filter disposed between the fluorescent member and the plurality of LEDs, and configured to selectively filter a first wavelength area of the tricolor light emitted from the fluorescent member toward the plurality of LEDs, and reflect a second wavelength area of the tricolor light emitted from the fluorescent member toward an output direction.