Directional Backlight Waveguide for Autostereoscopic Displays
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Solution Overview
Problem
Spatially multiplexed autostereoscopic display devices suffer from reduced spatial resolution, non-uniform viewing windows, image flicker, and limited viewing freedom due to the structure of pixel apertures and parallax components, which also increase image cross-talk and visual strain for observers.
Innovation Solution
A directional backlight system with a waveguide having opposed guide surfaces and a reflective end, which directs input light from localized sources into optical windows with controlled luminance distribution, using non-imaging optical elements to map luminous intensity distributions to lateral brightness distributions, reducing flicker and improving uniformity and viewing freedom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If defocusing of optical elements is applied to reduce image flicker, then flicker is reduced, but image cross talk increases and visual strain increases
Solution Approach 1:
The patent changes the angular distribution parameter of light output by using non-imaging optical elements to reshape the luminous intensity distribution. This allows maintaining focused optical windows (avoiding defocus cross-talk) while controlling the angular spread to reduce flicker through optimized light distribution characteristics.
2Reliability
If pixel aperture shape is adjusted to reduce flicker, then flicker is reduced, but display brightness decreases and addressing electronics are compromised
Solution Approach 1:
The patent introduces non-imaging optical elements as intermediary components between the light sources and the display medium. These elements reshape the light distribution to achieve uniform angular output and reduce flicker without modifying the pixel aperture structure, thereby preserving display brightness and addressing electronics integrity.
3Illumination intensity
If localized light sources are used in waveguide, then large area uniform illumination is achieved, but lateral luminance distribution varies with viewing angle
Solution Approach 1:
The patent transforms the angular distribution parameter of light from the waveguide by using non-imaging optical elements. These elements reshape the luminous intensity distribution to achieve uniform lateral luminance across different viewing angles, converting angle-dependent output into angle-independent uniform illumination.
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 provides efficient, multi-user autostereoscopic displays with improved 2D functionality, reduced flicker, and increased display brightness and uniformity, while minimizing luminance changes with viewing angles, thus enhancing observer experience and display efficiency.
Implementation Method 1
a reflective end facing the input end for reflecting input light from the input sources back through the waveguide
Implementation Method 2
first and second, opposed guide surfaces for guiding light along the waveguide
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
Disclosed is an imaging directional backlight apparatus for providing large area uniform directed illumination from localized light sources. Within an exemplary optical valve system, a waveguide comprises a stepped structure, where the steps comprise extraction features hidden to guided light, propagating in a first forward direction. Returning light propagating in a second backward direction may be refracted, diffracted, or reflected by the features to provide discrete illumination beams exiting from the top surface of the waveguide. Such controlled illumination may provide for efficient, multi-user autostereoscopic displays as well as improved 2D display functionality. Illumination uniformity is provided by the positioning, packaging, and optically modifying of individual input sources. The latter employs non-imaging and refractive optics.