Waveguide Mini-LED Backlight for Switchable Privacy Displays
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Solution Overview
Problem
Existing privacy displays lack switchable privacy functionality and efficient illumination systems that provide high dynamic range and reduced off-axis visibility, while conventional backlights are thick, inefficient, and unsuitable for flexible or free-form shapes.
Innovation Solution
A thin, switchable illumination apparatus using a catadioptric optical element with a waveguide and light turning optical component that provides a narrow output cone for privacy and a wide output for multiple users, incorporating a mini-LED array and a reflective layer for high efficiency and dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a plurality of light sources are arranged in an array to provide full-field illumination, then the illumination area is improved, but the number of components and device complexity increase
Solution Approach 1:
The illumination system is divided into multiple independent light sources arranged in an array, where each light source can be individually controlled. This segmentation allows the system to cover a large area while maintaining manageable complexity through modular design, enabling selective activation of specific light sources based on measurement needs.
Solution Approach 2:
Each light source in the array is designed to perform multiple functions: providing illumination for imaging, serving as a reflectance standard when activated alone, and enabling ratiometric measurements when combined with other sources. This multi-functionality reduces the need for separate components for different measurement modes.
2Measurement precision
If multiple light sources are used for ratiometric reflectance measurements, then measurement precision is improved, but the complexity of controlling and synchronizing light sources increases
Solution Approach 1:
The system employs dynamic control of light source activation, where different subsets of light sources are selectively turned on and off based on the specific measurement requirement. This dynamic approach allows the system to simplify control complexity by activating only the necessary light sources for each measurement type rather than requiring simultaneous control of all sources.
Solution Approach 2:
The system uses feedback mechanisms to monitor and adjust light source activation and detector responses. By measuring the actual light output and detector signals, the system can compensate for variations in light source intensity and timing, thereby maintaining measurement precision while managing control complexity through adaptive correction.
3Adaptability or versatility
If individual light sources are activated to serve as reflectance standards, then measurement capability is improved, but the time required for measurements increases
Solution Approach 1:
The system implements periodic activation of individual light sources in a systematic sequence, where each light source is activated for a brief period to serve as a reflectance standard. This periodic action allows the system to gather comprehensive measurement data over time while maintaining efficient throughput by rapidly cycling through the light source array.
Solution Approach 2:
The system performs preliminary characterization of each light source's output and the detector's response during initial calibration phases. This preliminary action stores reference data that can be used for subsequent measurements, reducing the time required during actual measurement operations by eliminating the need for repeated full calibration sequences.
4Volume of moving object
If detectors are positioned close to the light source array, then device compactness is improved, but the field of view and measurement area are limited
Solution Approach 1:
The system arranges detectors and light sources in a three-dimensional configuration rather than a simple planar layout. By utilizing vertical spacing and angular positioning, the system achieves a compact footprint while maintaining an extended effective measurement area through strategic geometric arrangement of the optical 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
Achieves high luminance and dynamic range with reduced off-axis visibility, enabling thin, flexible, and free-form displays with efficient power usage and reduced glare.
Implementation Method 1
An array of light sources provides illumination to a sample. Individual light sources in the array may be activated to serve as a reflectance standard or to enable ratiometric measurements of the sample.
Data Source
Figure 1A
Figure 1B~1C
Figure 1D
AI summary
A directional illumination apparatus comprises an array of light emitting diodes formed on a support substrate, a waveguide and a light turning optical component. An array of light input wells are arranged in the waveguide to receive light from the respective aligned array of light emitting diodes. An array of light deflecting wells are arranged in the waveguide to reflect guided light in the region around each light emitting diode. Extracted light from the waveguide is output by means of refraction and total internal reflection by a light turning optical component. A directional illumination output may be provided. A backlight for a high dynamic range display may achieve high efficiency and luminance. A privacy display with high security factor and high dynamic range may be achieved.