Rotationally Asymmetrical Collimator Lens for LED Illumination
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Solution Overview
Problem
Current illumination units in projector systems face inefficiencies due to non-collimated and non-directional light emission from LEDs, which results in low coupling efficiency and mismatched light distribution with the imager's aspect ratio, leading to suboptimal performance.
Innovation Solution
A collimator lens with a central and peripheral part, featuring rotationally asymmetrical surfaces, is designed to converge wide-angle light emission into a more directional and specific angular distribution, matching the projection optics and aspect ratio of the imager, thereby enhancing light collection and directionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a spherical or aspherical condenser lens is used to collect light from LED, then the light collection capability is improved, but the device size becomes large and bulky
Solution Approach 1:
The condenser lens is divided into multiple lens elements with different functions: a first condenser lens element for initial light collection and a second condenser lens element for further convergence. This segmentation allows each element to be smaller while collectively achieving high light collection efficiency, resolving the contradiction between collection capability and device size.
Solution Approach 2:
The patent introduces a planar light converting element that converts point-source LED light into area-source light, adding a dimensional transformation. This allows the light to be distributed over a larger area before entering the condenser lens, improving collection efficiency without requiring a large focal length, thus reducing the overall lens size.
2Volume of moving object
If a diffractive lens is used to reduce condenser lens thickness, then the device size is reduced, but scattering loss increases and coupling efficiency decreases
Solution Approach 1:
The patent employs a composite optical system combining refractive lens elements with specific surface profiles and a planar light converting element. This composite structure achieves both thin profile and high coupling efficiency by distributing optical functions across multiple elements rather than relying on a single diffractive surface that causes scattering.
3Device complexity
If the LED light emission is used directly without collimation, then the device complexity is reduced, but the light distribution does not match the imager aspect ratio and coupling efficiency is low
Solution Approach 1:
The patent applies local quality by using a planar light converting element that specifically transforms the angular distribution of light in certain regions. This element creates an area-source light distribution that matches the imager aspect ratio locally, improving coupling efficiency without requiring complex collimation optics throughout the entire system.
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 significantly improves the optical efficiency of projector systems by ensuring a high-matching illumination cone with the imager's aspect ratio, resulting in a compact and efficient illumination unit for small projector systems.
Implementation Method 1
The collimator lens includes a central part having a first light transmission surface and a second light transmission surface opposite to the first light transmission surface
Implementation Method 2
The peripheral part has an outer reflection wall opposite to the inner refraction wall
Data Source
AI summary
An illumination unit for emitting light along an optic axis for a projection system includes an LED die and a collimator lens. The collimator lens includes a central part and a peripheral part. The central part has a first light transmission surface and a second light transmission surface opposite to the first light transmission surface. The peripheral part which is around the central part has an inner refraction wall coupled to the first light transmission surface to form a hollow for situating the LED die, an outer reflection wall opposite to the inner refraction wall, and a refraction surface connecting to the second light transmission surface and the outer reflection wall. Both the central part and the peripheral part of the collimator lens are rotationally asymmetrical corresponding to the optic axis.