Stepped Waveguide Backlight for Autostereoscopic Displays
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Solution Overview
Problem
Autostereoscopic displays face issues with reduced spatial resolution, image flicker, and increased cross-talk due to the structure of viewing windows and the use of spatial light modulators, which limits viewing freedom and increases visual strain for observers.
Innovation Solution
A directional illumination apparatus using a stepped waveguide imaging directional backlight with an input optic to direct light into different directional distributions, achieving a two-dimensional array of windows for enhanced functionality, including vertical look-around and head tilt tracking, and providing efficient autostereoscopic displays with controlled illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If spatial light modulator with pixel aperture structure is used for autostereoscopic display, then viewing window structure is formed, but spatial resolution is reduced and image flicker occurs
Solution Approach 1:
The patent segments the viewing window structure into multiple independently controllable light sources positioned behind a transparent display panel. Each light source corresponds to a specific viewing window region, allowing independent illumination control that eliminates the need for pixel aperture structures while maintaining autostereoscopic functionality and preserving spatial resolution.
Solution Approach 2:
The patent introduces a transparent display panel as an intermediary component that separates the light source array from the viewer. This mediator allows light to pass through while providing the structural basis for forming viewing windows, eliminating the need to modify the pixel aperture structure of the display itself and thus preserving spatial resolution.
2Object-affected harmful factors
If pixel aperture shape is adjusted to reduce flicker, then viewing window uniformity improves, but display brightness is reduced
Solution Approach 1:
The patent extracts the viewing window formation function from the pixel aperture structure and relocates it to a dedicated light source array positioned behind the transparent display panel. This separation allows the pixel aperture to maintain its original high-brightness configuration while the external light sources provide uniform illumination control for flicker reduction.
Solution Approach 2:
The patent implements dynamic control of individual light sources in the array, allowing real-time adjustment of illumination intensity and timing for each viewing window region. This dynamic control eliminates flicker by synchronizing light emission with viewing conditions while maintaining optimal brightness levels independent of pixel aperture constraints.
3Object-affected harmful factors
If defocusing optical elements is used to reduce flicker, then image flicker decreases, but image cross talk increases
Solution Approach 1:
The patent applies local quality control by positioning and controlling each light source in the array to illuminate only its designated viewing window region. This localized illumination approach eliminates flicker through precise temporal control while maintaining sharp spatial boundaries that prevent image cross talk, as each light source affects only its specific region rather than the entire display area.
4Device complexity
If conventional edge emitting sources are used in waveguide, then simple structure is achieved, but directional control and viewing window formation capability are limited
Solution Approach 1:
The patent implements multi-functionality by using a transparent display panel that simultaneously serves as both the display medium and the structural support for the light source array. This universal component provides both the visual display function and the directional illumination control capability, eliminating the need for separate complex optical systems while enabling precise viewing window formation.
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 enhances spatial resolution, reduces flicker, and minimizes cross-talk, enabling larger area, thinner display structures with improved observer tracking and privacy features, while maintaining high brightness and efficiency.
Implementation Method 1
Light may propagate substantially without loss in one direction through the optical valve while counter-propagating light may be extracted by reflection off tilted facets
Implementation Method 2
an input optic located between the first and second light guiding surfaces, the input optic operable to direct light from each element of an array of illumination elements into respective different directional distributions within the imaging directional backlight
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A directional illumination apparatus comprises an imaging directional backlight for directing light, the imaging directional backlight comprising: an array of illumination elements; a waveguide comprising an input end, a first light guiding surface and a second light guiding surface, opposite the first light guiding surface; and an input optic located between the first and second light guiding surfaces. The input optic is configured to direct input light from each illumination element of the array of illumination elements into the waveguide through the input end into respective different directional distributions within the imaging directional backlight. The waveguide cooperates with the array of illumination elements and input optic to output the input light from the waveguide in directions that provide a two dimensional array of optical windows.