Planar Light Source Chromaticity Tuning for Uniform White Output
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Solution Overview
Problem
Light-emitting devices experience color unevenness due to chromaticity differences between light emitted through a light-scattering member and light emitted laterally, caused by Rayleigh scattering, which affects the desired white light output.
Innovation Solution
Incorporating a light-adjustment member with higher absorptance at the peak wavelength of the second light than the first light within the light-scattering member, ensuring that the second light is more absorbed, thereby aligning the chromaticity of the mixed light with the laterally emitted light, reducing color unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light-scattering member is used to emit light, then light distribution is improved, but color uniformity deteriorates due to chromaticity differences between light emitted through the member and light emitted laterally
Solution Approach 1:
The patent applies local quality by providing a light-adjustment member with spatially varying optical properties. The member has different absorptance at different wavelengths (higher at second light wavelength than first light wavelength), creating localized chromaticity adjustment in specific regions of the light-scattering member to compensate for Rayleigh scattering effects and achieve uniform color output.
Solution Approach 2:
The patent changes optical parameters by introducing a light-adjustment member with specific spectral absorptance characteristics. The member is designed to have higher absorptance at the peak wavelength of second light than at the peak wavelength of first light, thereby modifying the chromaticity of emitted light to match between different emission paths and reduce color unevenness.
2Manufacturing precision
If a light-adjustment member with higher absorptance at second light wavelength is added, then color uniformity is improved, but device complexity increases
Solution Approach 1:
The patent merges the light-adjustment member with the light-scattering member into an integrated structure. The light-adjustment member is provided within or on the light-scattering member, combining multiple functions (light scattering and chromaticity adjustment) into a single integrated component rather than separate elements, thereby reducing overall device complexity.
Solution Approach 2:
The light-scattering member serves multiple functions: it scatters light to improve distribution and simultaneously houses or supports the light-adjustment member that corrects chromaticity. This multi-functionality reduces the need for additional separate components, thereby managing device complexity while achieving color uniformity.
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 solution effectively reduces color unevenness by ensuring the chromaticity of the third light emitted through the light-scattering member matches the chromaticity of the fourth light emitted laterally, achieving a uniform white light output with a difference of 10/1,000 or less.
Implementation Method 1
a wavelength conversion material configured to absorb a portion of the first light and emit second light
Implementation Method 2
a light-scattering member disposed on the light-transmissive member, including a light-scattering material
Implementation Method 3
a light-adjustment member provided in the light-scattering member or on the light-scattering member, and having a higher absorptance or a higher reflectance at the peak wavelength of the second light
Data Source
AI summary
A light-emitting device includes: a light-emitting element configured to emit first light; a light-transmissive member covering an upper surface of the light-emitting element and including a wavelength conversion material configured to absorb a portion of the first light and emit second light; a light-scattering member disposed on the light-transmissive member, including a light-scattering material, and having a higher reflectance at a peak wavelength of the first light than at a peak wavelength of the second light; and a light-adjustment member located in or on the light-scattering member and having either (i) a higher absorptance at the peak wavelength of the second light than at the peak wavelength of the first light, or (ii) a higher reflectance at the peak wavelength of the second light than at the peak wavelength of the first light. A lateral surface of the light-transmissive member is exposed from the light-scattering member and the light-adjustment member.