Backlight Light Guide with TIR Collimators for Narrow Emission
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Solution Overview
Problem
Existing edge-lit backlight systems struggle to achieve narrow angular light distribution and homogeneous illumination while maintaining efficiency, which is necessary for applications like head-up displays and switchable privacy screens.
Innovation Solution
A light guide with total internal reflection collimators and a reflective inclined end face is used to control angular distribution, combined with outcoupling structures and polarization recycling to achieve narrow and homogeneous light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If edge-lit light guide configuration is used, then the system is compact and efficient, but the angular distribution is wide and cannot achieve narrow light distribution
Solution Approach 1:
The light guide is divided into functionally distinct segments: a light incoupling portion with total internal reflection collimators for narrow angular distribution, and a light guiding portion for homogeneous illumination. This segmentation allows each segment to optimize its specific function while working together as a compact system.
Solution Approach 2:
Different regions of the light guide are assigned different optical properties: the incoupling portion features collimators with specific geometries (prisms, gratings, or textured surfaces) to control angular distribution, while the guiding portion has reflective or diffusive properties for homogeneous light distribution. This local differentiation resolves the contradiction between narrow angular distribution and compact size.
2Illumination intensity
If direct-lit systems with collimation optics are used, then narrow light distribution is achieved, but the space required is much larger compared to edge-lit systems
Solution Approach 1:
The patent merges the collimation function and light guiding function into a single integrated light guide component. The incoupling portion with collimators and the guiding portion work together in one piece, eliminating the need for separate collimation optics and reducing overall system size while maintaining narrow angular distribution.
Solution Approach 2:
The light guide serves multiple functions simultaneously: it acts as both a collimation element (through the incoupling portion with total internal reflection collimators) and a light distribution element (through the guiding portion). This multi-functionality eliminates the need for separate components, achieving narrow angular distribution in a compact form.
3Illumination intensity
If additional components such as diffuser films, prism films, or coatings are added to improve efficiency and homogeneity, then the light distribution is improved, but the device complexity increases
Solution Approach 1:
The patent combines the functions of collimation and light guiding into a single integrated light guide component. The incoupling portion with total internal reflection collimators and the light guiding portion work together in one piece, eliminating the need for separate diffuser films, prism films, or coatings that would increase device complexity.
Solution Approach 2:
The light guide is designed as a multi-functional component that simultaneously performs collimation (through the incoupling portion) and homogeneous light distribution (through the guiding portion with reflective or diffusive properties). This universal design achieves improved light distribution without adding multiple separate components.
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 controlled angular distribution, suitable for various display applications including automotive head-up displays and switchable privacy screens.
Implementation Method 1
the at least one light incoupling portion has an arrangement of total internal reflection collimators
Implementation Method 2
the light guiding portion has a reflective inclined end face
Data Source
AI summary
A light guide for a backlight unit, a backlight unit having such a light guide, and to a display device having such a backlight unit. The light guide has at least one light incoupling portion having an arrangement of total internal reflection collimators and a light guiding portion. The light guiding portion has a reflective inclined end face a top side, and an underside. The light guiding portion guides the light coming from the light incoupling portion within the light guiding portion to the inclined end face, and outcouples the light reflected by the inclined end face through the top side.