Light Source Unit Etendue Optimization for Projectors
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Solution Overview
Problem
Existing projectors using light emitting diodes face inefficiencies in light utilization due to a larger Etendue of the light source unit compared to the display device, leading to reduced luminance and increased unusable light, particularly with green light emitting diodes requiring more units and increasing the light emitting area, thus lowering effective light ratios.
Innovation Solution
A light source unit design featuring a luminescent light source with excitation light sources arranged as surface illuminants on a flat surface, a reflection space, and an emission space with a smaller emission port, optimized to enhance light utilization efficiency by maintaining a smaller Etendue and increasing light quantity, using a red, green, and blue light source configuration with specific wavelength band generation devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple light emitting diodes are disposed to increase light quantity, then the light emitting area increases, but the Etendue becomes larger than the display device Etendue, reducing light utilization efficiency
Solution Approach 1:
The patent transitions from a planar array of multiple LEDs to a three-dimensional volumetric light source configuration. By arranging LEDs in a 3D space with specific spatial relationships (including inverted arrangements), the system increases light quantity while controlling the projected emission area, thereby maintaining favorable Etendue characteristics.
Solution Approach 2:
The light source is divided into multiple discrete LED elements arranged in specific spatial patterns rather than using a single large-area source. This segmentation allows precise control over the spatial distribution of light emission, enabling the system to achieve high light quantity while maintaining compact effective emission area.
2Quantity of substance
If green light emitting diodes are increased to compensate for lower efficiency, then the number of diodes increases, but the light emitting area expands, further reducing effective light ratio
Solution Approach 1:
The patent employs vertical stacking and three-dimensional arrangement of green LEDs rather than planar expansion. This allows increasing green light quantity by utilizing the third dimension (height/depth), thereby avoiding expansion of the horizontal emission area that would worsen Etendue matching.
Solution Approach 2:
Different regions of the light source assembly have specialized functions: green LEDs are concentrated in specific volumetric regions with optimized spatial distribution, while other colors are arranged in complementary patterns. This local optimization ensures green light quantity is maximized without proportionally increasing overall emission area.
3Illumination intensity
If a plurality of light emitting diodes are combined to achieve desired luminance, then the light quantity increases, but the Etendue mismatch with display device increases, causing more unusable light
Solution Approach 1:
The patent uses volumetric LED arrangements that project a smaller effective emission area compared to planar arrays. This 3D configuration allows achieving high luminance through increased light quantity while maintaining favorable Etendue characteristics for better optical system matching.
Solution Approach 2:
Multiple LED elements are combined in a unified volumetric structure with integrated optical management. The combined structure achieves high luminance while the unified design allows optimized light extraction and emission patterns that reduce Etendue mismatch with the display device.
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 design enhances the utilization efficiency of light emitting diodes, increasing the quantity of usable light and achieving higher luminance in projected images by optimizing the light source unit's Etendue and light distribution, specifically addressing the inefficiencies in green light emission.
Implementation Method 1
a luminescent light source which emits light of a predetermined wavelength band by receiving excitation light
Implementation Method 2
a luminescent light source which emits light of a predetermined wavelength band by receiving excitation light
Implementation Method 3
a reflection space having the luminescent light source in an interior thereof
Data Source
AI summary
There is provided a light source unit which includes a luminescent light source which receives excitation light so as to emit light of a predetermined wavelength band, excitation light sources which shine excitation light on to the luminescent light source, a reflection space having the luminescent light source in an interior thereof and an emission space which emits luminescent light source light emitted from the reflection space from an emission port whose area is made smaller than the area of the luminescent light source and a projector which employs the light source unit.