Fluorescent Plate Light Source for Projection Displays
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Solution Overview
Problem
Projection display apparatuses using solid-state light sources face issues with image quality due to speckles in green light and poor light-emitting efficiency, particularly with green LEDs, leading to insufficient brightness and imbalance in red, blue, and green light intensities, which affects the representation of white colors.
Innovation Solution
A light source device utilizing a fluorescent plate with a substrate and reflective films, excited by multiple solid-state light sources, including blue semiconductor lasers and LEDs, to emit balanced fluorescence in different directions, which are then optically combined to enhance brightness and color balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single red LED light source is used, then the device complexity is reduced, but the red light output power is insufficient
Solution Approach 1:
The patent combines multiple red LED light sources into a single illumination system to increase the total red light output power. By merging several light sources that emit the same color, the system achieves sufficient red light intensity without requiring separate independent systems for each color channel.
Solution Approach 2:
The patent uses the same blue laser light source to serve dual functions: generating blue light directly and exciting green fluorescent material to generate green light. This multi-functionality approach allows one light source to contribute to multiple color channels, reducing the total number of required light sources while maintaining balanced color output.
2Illumination intensity
If multiple light sources are used for each color to enhance brightness, then the brightness is improved, but the number of parts increases
Solution Approach 1:
The blue laser light source performs multiple functions by directly providing blue light and simultaneously exciting green fluorescent material to produce green light. This approach allows one light source to contribute to multiple color channels, reducing the total number of required light sources while maintaining balanced color output.
Solution Approach 2:
The patent combines multiple red LED light sources into a single illumination system to increase the total red light output power. By merging several light sources that emit the same color, the system achieves sufficient red light intensity without requiring separate independent systems for each color channel.
3Use of energy by moving object
If green LED light sources are used, then the device complexity is reduced, but the light-emitting efficiency is poor
Solution Approach 1:
The patent introduces green fluorescent material as an intermediary that converts blue light from the laser source into green light. This fluorescence conversion approach achieves high green light efficiency by using the high-efficiency blue laser to excite the fluorescent material, avoiding the use of inefficient green LEDs while maintaining a relatively simple light source configuration.
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 achieves enhanced brightness and balanced color representation by efficiently extracting and combining fluorescence from multiple light sources, minimizing temperature increase in the fluorescent material and reducing the device's dimensions, thereby improving the overall image quality and reducing non-uniformity in brightness and color.
Implementation Method 1
a fluorescent plate in which a substrate has a surface to which a fluorescent material is applied; a first optical system configured to optically guide, to a light combining section, fluorescence emitted in a first direction by the excitation light being applied to the fluorescent material
Implementation Method 2
a fluorescent plate in which a substrate has a surface to which a fluorescent material is applied; a first optical system configured to optically guide, to a light combining section, fluorescence emitted in a first direction
Data Source
AI summary
A solid-state light source unit emits excitation light. Fluorescent material layer is formed on each side of a glass substrate of a fluorescent plate so as to interpose a reflective film therebetween. The first optical system optically guides, to a rod integrator, red and blue LED light, and green fluorescence that is generated by excitation occurring when blue laser light emitted from the solid-state light source unit is applied to the fluorescent material layer on one surface of the fluorescent plate, and that is emitted in the −X direction. The second optical system optically guides, to the rod integrator, red and blue LED light, and green fluorescence that is generated by excitation occurring when blue laser light emitted from the solid-state light source unit is applied to the fluorescent material layer on the other surface of the fluorescent plate, and that is emitted in the +X direction.