Backlight Light Guide With TIR Collimators for Narrow Beam Output
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Solution Overview
Problem
Conventional edge-lit backlight units for displays struggle to achieve a narrow angular light distribution with high efficiency and homogeneous illumination, which is necessary for applications like head-up displays and switchable privacy screens, while direct-illuminated systems require excessive space.
Innovation Solution
A light guide with an array of total internal reflection collimators and a reflective inclined end surface, combined with microstructures and output structures, to control light propagation and achieve narrow angular distribution and efficient light mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If edge-lit backlight units are used, then the system remains compact, but the angular light distribution becomes wide rather than narrow
Solution Approach 1:
The light guide is segmented into multiple functional sections: a light coupling section with total internal reflection collimators, a conical light mixing section, and a light guiding section with output structures. This segmentation allows each section to perform its specific function optimally while maintaining overall system compactness and achieving narrow angular distribution.
Solution Approach 2:
The patent introduces a conical light mixing section that adds a dimensional transformation to the light path. The conical geometry transforms the wide angular distribution from LED sources into a narrow angular distribution by guiding light through a three-dimensional tapered structure, enabling narrow beam control without increasing system footprint.
2Illumination intensity
If direct-illuminated systems are used to achieve narrow light distribution, then the angular distribution becomes narrow, but the space required increases significantly
Solution Approach 1:
The light mixing section is designed with a conical geometry that nests within the light guide structure. The conical light mixing section is positioned inside the overall light guide assembly, allowing the light to be mixed and collimated in a compact nested configuration rather than requiring separate external components.
Solution Approach 2:
The light guide uses thin film or plate structures with integrated optical features. The light guiding section is implemented as a thin component with output structures formed on its surface, eliminating the need for bulky three-dimensional light mixing chambers while achieving the same optical effects.
3Volume of moving object
If conventional edge-lit configurations are used, then the system remains compact, but the illumination homogeneity deteriorates
Solution Approach 1:
Different sections of the light guide are given different local properties: the light coupling section has total internal reflection collimators for efficient light capture, the conical light mixing section has tapered geometry for uniform light distribution, and the light guiding section has output structures for controlled light extraction. This local differentiation ensures homogeneous illumination across the entire display surface.
Solution Approach 2:
The conical light mixing section acts as an intermediary between the LED light sources and the display panel. It receives light from the coupling section, mixes and redistributes the light uniformly through its tapered geometry, and then delivers the homogenized light to the guiding section for final output to the display.
4Illumination intensity
If additional optical components are added to improve efficiency and homogeneity, then the optical performance improves, but the device complexity increases
Solution Approach 1:
Multiple optical functions are merged into a single integrated light guide component. The light guide combines the light coupling section with total internal reflection collimators, the conical light mixing section, and the light guiding section with output structures into one unified part, eliminating the need for separate diffuser films, prism films, and other discrete optical components.
Solution Approach 2:
The light guide structure serves multiple functions simultaneously: it couples light from LED sources, mixes and homogenizes the light distribution, guides the light across the display surface, and extracts light at controlled locations. This multi-functionality reduces the overall component count while maintaining high optical 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
The solution enables a compact, efficient, and homogeneous illumination with a narrow angular distribution, suitable for various display applications including automotive displays and head-up displays.
Implementation Method 1
an array of total internal reflection collimators
Implementation Method 2
a reflective inclined end surface... guides the light coming from the light coupling section within the light guiding section to the inclined end surface, and couples out the light reflected from the inclined end surface
Data Source
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AI summary
The present invention relates to a light guide (3) for a backlighting unit. The invention further relates to a backlighting unit comprising such a light guide (3) and to a display device comprising such a backlighting unit.The light guide (3) comprises at least one light coupling section (30), wherein the at least one light coupling section (30) comprises an arrangement of total internal reflection collimators (300), and a light guide section (32), wherein the light guide section (32) comprises a reflective inclined end surface (326), and wherein the light guide section (32) comprises a top surface (320) and a bottom surface (321), wherein the light guide section (32) is configured to guide the light (L3) coming from the light coupling section (3) within the light guide section (32) to the inclined end surface (326), and couples the light (Lg) reflected from the inclined end surface (326) out through the top surface (320).