Color Mixing Illumination Light Unit Using Controlled Transmission Mirror
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Solution Overview
Problem
In larger or brighter displays, achieving uniform brightness and color across the display panel is challenging due to the limitations of light sources being either point sources or emitting different colors, which requires effective light spreading and mixing to prevent dark areas and color inconsistencies.
Innovation Solution
An optical system with a backlight unit that includes multiple light sources of different wavelengths, a reflecting cavity, and a controlled transmission mirror with input and output coupling elements and a multilayer reflector to redirect and transmit light, ensuring uniform illumination and color mixing across the display panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light sources are positioned to the side of the display panel, then the display can be smaller or less bright, but the light power requirements increase with the square of the display size making this arrangement insufficient for larger or brighter displays
Solution Approach 1:
The patent transitions from edge-lit (side placement) to back-lit (behind panel placement) configuration, changing the spatial dimension where light sources are positioned. This allows sufficient light power delivery for large displays by placing multiple light sources directly behind the display panel rather than constrained to the edges.
2Device complexity
If point light sources such as LEDs are used, then the device complexity is reduced, but the illuminance uniformity deteriorates creating dark areas in the backlight
Solution Approach 1:
The patent introduces a light guide with varying optical properties at different locations. The light guide includes a light incident surface and a light output surface with specific optical characteristics that vary spatially, allowing uniform light distribution across the display panel while maintaining simple LED point sources.
Solution Approach 2:
The light guide acts as an intermediary between the point light sources and the display panel. It receives light from LEDs and redistributes it uniformly across the panel through its optical structure, including reflecting surfaces and light extraction features.
3Adaptability or versatility
If multiple LEDs of different colors are used, then the color variety is improved, but the color uniformity deteriorates requiring effective light mixing
Solution Approach 1:
The patent combines light from multiple LEDs of different colors within a single light guide structure. The light guide merges these different color lights and redistributes them uniformly across the display panel, achieving both color variety and color uniformity.
Solution Approach 2:
The light guide has spatially varying optical properties that enable different regions to contribute to overall color mixing. The light extraction features and reflecting surfaces are distributed to ensure uniform color distribution across the entire display panel.
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 achieves uniform brightness and color across the display panel by effectively spreading and mixing light from different sources, enhancing the overall image quality and brightness, particularly in larger or brighter displays.
Implementation Method 1
The first multilayer reflector is reflective for normally incident light from the first and second light sources
Implementation Method 2
a first multilayer reflector between the input and output coupling elements
Implementation Method 3
The input coupling element redirects at least some of the light propagating from the first and second light sources in a direction substantially perpendicular to the first multilayer reflector into a direction that is transmitted through the first multilayer reflector
Data Source
AI summary
An illumination light unit includes at least two light sources that generate light at different wavelengths. The illumination light unit also includes a reflecting cavity having one or more reflectors and a controlled transmission mirror disposed at an output of the reflecting cavity. The controlled transmission mirror includes an input coupling element, an output coupling element and a first multilayer reflector disposed between the input and output coupling elements. At least some of the light from the light sources is reflected within the reflecting cavity by the one or more reflectors and is mixed. Light passes out of the reflecting cavity through the controlled transmission mirror. The illumination light unit may be used for illumination purposes, or as part of a backlight for illuminating a display.