Tapered Light Guide Narrow Angle Output
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Solution Overview
Problem
Conventional light guides are inadequate in distributing light uniformly, especially for wide-angle light sources, leading to non-uniform illumination in display devices and other lighting applications due to insufficient total internal reflection (TIR), resulting in reduced brightness and efficiency.
Innovation Solution
A light guide system with a bar-shaped structure featuring tapered side walls and light extraction elements, such as scattering features or facets, that collimate and redirect light to maintain a narrow output angle range, enhancing light distribution and uniformity by increasing the amount of light experiencing TIR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a light source is directly optically coupled to a light guide, then light extraction is simplified, but light uniformity deteriorates due to insufficient total internal reflection
Solution Approach 1:
The light guide incorporates localized light extraction elements (such as prisms, scatterers, or reflective features) at specific positions along its length. These localized features create regions of enhanced light extraction while maintaining TIR in other regions, thereby achieving uniform illumination without requiring complete optical decoupling of the light source.
Solution Approach 2:
The invention introduces a vertical dimension to light extraction by incorporating features that redirect light from horizontal propagation paths to vertical extraction paths. This dimensional transformation enables controlled light extraction while preserving the simplicity of direct optical coupling.
2Area of stationary object
If wide angle light sources are used, then illumination coverage is improved, but light uniformity deteriorates due to insufficient TIR
Solution Approach 1:
The invention modifies the optical parameters of the light guide by incorporating features that change the propagation angles of light. These features redirect wide-angle light paths into narrower angles that satisfy TIR conditions, thereby maintaining illumination coverage while improving uniformity.
Solution Approach 2:
The light guide acts as an intermediary between the wide-angle light source and the display elements. By incorporating TIR-enhancing features, the light guide mediates the light distribution, converting wide-angle illumination into uniform directional light while maintaining coverage.
3Illumination intensity
If more light extraction elements are added, then light uniformity is improved, but device complexity increases
Solution Approach 1:
The light guide is segmented into functional regions with different extraction characteristics. By dividing the light guide into segments with specific features (prisms, scatterers, reflective surfaces), the invention achieves uniform illumination through modular, manageable structures rather than a single complex element.
Solution Approach 2:
The light guide employs composite structures combining different materials or optical properties within the same component. This allows multiple functions (light propagation, extraction, and direction control) to be integrated into a single unified structure, reducing overall device complexity while maintaining performance.
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 proposed light guide system improves light uniformity and brightness in display devices and lighting applications by effectively collimating and redirecting light, reducing the number of light sources required and allowing for flexible lighting designs.
Implementation Method 1
Some available light guides are not capable of distributing light in configurations that are appropriate for particular lighting applications. For example, in some cases, a light source can be directly optically coupled to a light guide. For light sources providing a wide angle output of light, some light can enter the light guide at angles that do not experience total internal reflection (TIR)
Implementation Method 2
The light guide can include one or more tapered side walls that extend from the output surface to the back side, and the tapered side walls can be configured to partially collimate the light directed out of the output surface. A longitudinal axis can extend along the length of the light guide, and the one or more side walls of the light guide can be configured to partially collimate the light directed out of the output surface such that light that exits the output surface in a plane substantially orthogonal to the longitudinal axis can be substantially confined to a range of output angles of about ±60° or less relative to a direction normal to the output surface.
Implementation Method 3
Light extraction elements can be dispersed along the length of the light guide, and the light extraction elements can be configured to direct light out of the light guide through the output surface.
Data Source
AI summary
This disclosure provides systems, methods, and apparatus for providing illumination. In one aspect, a light guide can be configured to propagate light received from a light source. The light can be propagated by total internal reflection (TIR) within the light guide. The light guide can include an output surface configured to output light and one or more light extraction elements, which are configured to redirect the light propagating in the light guide so that the light exits the light guide through the output surface. The light guide can have tapered side walls that are configured to at least partially collimate the light that is to exit out of the output surface. In some implementations, the light guide can be used to provide illumination for display devices, other electromechanical systems, or for lighting a room or task area.