Directional Backlight Waveguide Segmentation for Wide-Angle Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Spatially multiplexed autostereoscopic displays face issues with reduced spatial resolution, image flicker, and non-uniform viewing windows due to gaps between pixels, leading to limited viewing freedom and increased visual strain, which existing solutions attempt to address by defocusing optical elements or modifying pixel aperture shapes at the cost of brightness and complexity.
Innovation Solution
A directional backlight apparatus with a waveguide and an array of light sources positioned laterally across the input end, where the reflective end converges reflected light to illuminate outer portions of the waveguide, and a control system operates light sources to direct light into selectable viewing windows, ensuring uniform illumination and reducing void regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a curved reflecting mirror is used to collimate light in imaging directional backlights, then light propagation efficiency is improved, but off-axis viewing positions create non-illuminated outer portions reducing display area
Solution Approach 1:
The waveguide is divided into multiple segments or regions, with different optical path configurations for on-axis and off-axis viewing. This segmentation allows the system to optimize light propagation for each region while maintaining overall display area utilization.
Solution Approach 2:
The patent introduces a folded optical path that utilizes the thickness dimension of the waveguide to redirect light from off-axis sources. By folding the optical path through multiple reflections, light from off-axis positions can reach areas that would otherwise remain dark, effectively utilizing the third dimension to solve the area limitation.
2Stability of the object's composition
If spatially multiplexed autostereoscopic displays use pixel aperture modifications to reduce flicker, then image stability is improved, but display brightness is reduced
Solution Approach 1:
The patent introduces an intermediary optical element (such as a microlens array or directional control layer) between the light source and the pixel aperture. This intermediary redirects and concentrates light in a way that maintains image stability while preserving brightness, avoiding the need to modify the pixel aperture itself.
Solution Approach 2:
The system dynamically adjusts optical parameters such as the focal length of microlenses or the orientation of directional control elements to optimize both image stability and brightness. By changing these parameters in response to viewing conditions, the system maintains stable images without sacrificing display brightness.
3Adaptability or versatility
If defocusing optical elements is used to reduce image flicker, then viewing freedom is improved, but image cross talk increases
Solution Approach 1:
The patent employs dynamically adjustable optical elements that can change their focusing state based on the desired viewing mode. When wide viewing freedom is needed, the elements adopt a defocused state; when image separation is critical, they switch to a focused state, thus dynamically balancing viewing freedom and cross-talk reduction.
Solution Approach 2:
Different regions of the optical system have different focal characteristics. The patent creates zones with varying optical properties, where central regions maintain sharp focus for primary viewing positions while peripheral regions are intentionally defocused to expand viewing freedom, thereby locally optimizing both parameters without excessive cross-talk.
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 brightness, reduces image flicker, and increases viewing freedom by uniformly illuminating the spatial light modulator, allowing for wider angle viewing and more efficient use of the display area while maintaining a thin form factor.
Implementation Method 1
a waveguide for guiding light
Implementation Method 2
a reflective end for reflecting the input light back through the waveguide
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
An imaging directional backlight apparatus including a waveguide, a light source array, for providing large area directed illumination from localized light sources. The waveguide may include a stepped structure, in which the steps may further include extraction, features optically 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. Viewing windows are formed through imaging individual light sources and hence defines the relative positions of system elements and ray paths. The uncorrected system creates non-illuminated void portions when viewed off-axis preventing uniform wide angle 2D illumination modes. The system may be corrected to remove this non uniformity at wide angles through the introduction of additional sources away from the system's object plane, additional imaging surfaces, and/or by altering ray paths.