Illumination Device with Segmented Color Conversion for White Light
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Solution Overview
Problem
Current liquid crystal display devices using pseudo white LEDs face challenges in achieving high color reproducibility and intensity efficiency due to limited light components in the 600 nm wavelength region and chemical reactions between phosphors and reflective films, leading to deteriorated reflection characteristics and low intensity efficiency.
Innovation Solution
An illumination device structure is implemented where a first color conversion element converts blue light into red light and a second color conversion element converts blue light into green light, with both elements separated to produce white light, avoiding chemical interactions and enhancing light emission efficiency and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If chalcogenide phosphor or nitride phosphor doped with rare-earth element is used to convert blue light into green or red light, then color reproducibility is improved, but chemical reaction with reflective film causes reflection characteristic deterioration
Solution Approach 1:
The patent divides the color conversion function into separate modules: a first color conversion element for green light and a second color conversion element for red light, both positioned on the optical path but separated from each other and from the blue LED. This segmentation prevents direct contact between the phosphors and the reflective film, eliminating the chemical reaction problem while maintaining high color reproducibility through additive mixing of three wavelengths.
2Illumination intensity
If green phosphor and red phosphor are mixed to produce white light based on blue excitation, then color reproducibility is improved, but intensity efficiency decreases due to excitation wavelength overlap
Solution Approach 1:
The patent separates the green and red color conversion elements into distinct modules positioned at different locations on the optical path. The blue LED light first passes through the first color conversion element (green phosphor), then through the second color conversion element (red phosphor). This sequential arrangement ensures that green light emitted by the first element does not re-excite the red phosphor in the second element, eliminating the efficiency loss from wavelength overlap while maintaining high color reproducibility.
3Use of energy by moving object
If pseudo white LED with YAG phosphor is used, then intensity efficiency is improved, but color reproducibility deteriorates due to limited light components in 600 nm wavelength region
Solution Approach 1:
The patent employs a composite illumination system that combines blue LED light with two separate phosphor conversion elements: one converting blue light to green and another converting blue light to red. This composite approach creates a three-wavelength white light source that maintains the high intensity efficiency of LED technology while achieving superior color reproducibility across the visible spectrum, particularly in the red region (600 nm and above) where conventional YAG phosphor fails.
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 color reproducibility and intensity efficiency by additive mixing of three colors, increasing light emission efficiency and reliability while preventing chemical reactions between phosphors and the blue light emitting element.
Implementation Method 1
a blue light emitting element
Implementation Method 2
a first color conversion element for converting blue light into red light
Implementation Method 3
a second color conversion element for converting blue light into green light
Data Source
AI summary
An illumination device has a blue light emitting element that emits blue light and a light guide member that guides blue light emitted from the blue light emitting element to a light exit surface of the light guide member. A first color conversion element includes a red phosphor that emits red light in response to excitation with the blue light. The first color conversion element is disposed on an optical path between the blue light emitting element and the light guide member. A second color conversion element is disposed on a light exit surface side of the light guide member and separated from the first color conversion element. The second color conversion element comprises a pair of non-permeable transparent substrates, a resin disposed between the non-permeable transparent substrates, and a green phosphor dispersed in the resin for emitting green light in response to excitation with the blue light.