Wavelength Conversion Member Activator Gradient for Projector Light Source
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing light source apparatuses for projectors face issues with excess reabsorption of fluorescence by the activator in the wavelength conversion member, leading to light scattering, self-absorption, and non-uniform temperature distribution, which decrease wavelength conversion efficiency and color tone accuracy.
Innovation Solution
A light source apparatus with a wavelength conversion member containing a phosphor and a reflection member, where the activator concentration is set to absorb less than 98% of the excitation light, and a reflection member is placed to reflect unabsorbed light back for reabsorption, reducing scattering and self-absorption, and a support member for heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the activator concentration is increased to absorb 98% or more of excitation light, then the wavelength conversion efficiency is improved, but the fluorescence is excessively reabsorbed by the activator causing light scattering and self-absorption
Solution Approach 1:
The phosphor layer is divided into two regions with different activator concentrations: a first region closer to the excitation light source with lower activator concentration (0.01-5 wt%) to reduce self-absorption, and a second region farther from the source with higher activator concentration (5-20 wt%) to maximize light absorption. This spatial variation in activator concentration resolves the contradiction by optimizing both efficiency and reducing harmful effects in different locations.
Solution Approach 2:
The invention transitions from a uniform activator concentration approach to a gradient concentration distribution along the depth direction (z-axis) of the phosphor layer. By introducing a dimensional variation in activator concentration, the system achieves optimal wavelength conversion efficiency while minimizing self-absorption and light scattering effects that occur with uniform high concentration.
2Illumination intensity
If the activator concentration is increased to absorb more excitation light, then the amount of fluorescence emitted is improved, but the color tone accuracy deteriorates due to excess reabsorption
Solution Approach 1:
The phosphor layer uses spatially varying activator concentrations to optimize both fluorescence output and color accuracy. The first region (lower concentration) maintains color tone accuracy by reducing self-absorption, while the second region (higher concentration) maximizes fluorescence emission, achieving both goals simultaneously through local optimization.
3Loss of energy
If the activator concentration is increased to improve wavelength conversion, then the light absorption is improved, but the temperature distribution becomes non-uniform causing efficiency decrease
Solution Approach 1:
The gradient activator concentration distribution spreads heat generation more uniformly throughout the phosphor layer. The lower concentration in the first region generates less heat near the excitation source, while the higher concentration in the second region captures more light energy deeper in the layer, creating a more balanced thermal profile that maintains wavelength conversion efficiency.
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 increases the amount of fluorescence emitted, improves color reproducibility, and maintains stable wavelength conversion efficiency by reducing light scattering and self-absorption, while ensuring desired color tone generation.
Implementation Method 1
a wavelength conversion member that contains a phosphor and converts the first light outputted from the light emitter into second light having a second wavelength band different from the first wavelength band
Implementation Method 2
a reflection member that reflects the first light that enters the wavelength conversion member
Implementation Method 3
An activator contained in the phosphor has a concentration required to absorb the first light by an amount smaller than 98% of an amount of the incident first light
Data Source
AI summary
A light source apparatus according to an aspect of the present disclosure includes a light emitter that outputs first light having a first wavelength band, a wavelength conversion member that contains a phosphor, and a reflection member that reflects the first light that enters the wavelength conversion member. The wavelength conversion member has a first surface and a second surface located at the sides opposite from each other in a first direction, and a third surface and a fourth surface located at the sides opposite from each other in a second direction that intersects with the first direction. An activator contained in the phosphor has a concentration required to absorb the first light by an amount smaller than 98% of the amount of the incident first light in the path along which the first light incident via the third surface travels to the fourth surface.