Dual Light Guide Grating Backlight for Uniform Illumination
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Solution Overview
Problem
Passive electronic displays, such as LCDs and EP displays, lack the ability to emit light, limiting their practical applications due to their reliance on external light sources, which can result in non-uniform illumination and reduced performance.
Innovation Solution
A dual light guide, grating-based backlight system that employs a first light guide to propagate light, a redirection coupler to redirect the light, and a multibeam diffraction grating to scatter and couple light out of a second light guide, providing uniform illumination and enabling the display of 3D information without the need for glasses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional backlight is used to illuminate passive displays, then the display can emit light and function as an active display, but the illumination is non-uniform and performance is reduced
Solution Approach 1:
The patent divides the backlight system into multiple segments: a light source, a light guide plate, and multiple diffraction gratings positioned at different locations. Each segment contributes to directing light toward specific viewing angles, collectively achieving uniform illumination across the display surface while maintaining high display performance
Solution Approach 2:
The patent applies diffraction gratings with specific properties at specific locations within the backlight system. Each grating is positioned to address local illumination needs, creating zones of optimized light distribution that collectively achieve uniform overall illumination while enhancing display performance in different viewing directions
2Use of energy by moving object
If passive displays rely on external light sources, then they can be manufactured with low power consumption, but they lack the ability to emit light independently
Solution Approach 1:
The patent introduces a light guide plate as an intermediary between the light source and the display. This intermediary component captures light from an external source and redistributes it uniformly across the display while maintaining energy efficiency. The system preserves the low power consumption advantage of passive displays while adding controlled light emission capability through the intermediary light guide structure
3Device complexity
If a single light guide is used, then the structure is simple, but the ability to direct light at different angular directions is limited
Solution Approach 1:
The patent transitions from a single light guide to multiple light guides arranged in different spatial dimensions and orientations. Each light guide directs light at specific angular directions, creating a multi-dimensional light distribution pattern. This dimensional expansion enables the system to provide light at multiple viewing angles while maintaining relatively simple individual guide structures
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 system achieves improved uniformity and effectiveness in illumination, allowing for the creation of 'glasses-free' 3D color electronic displays by directing light beams at different principal angular directions, enhancing the display's ability to represent multiple views and colors.
Implementation Method 1
a first light guide to guide light as a first light beam in a first direction
Implementation Method 2
a redirection coupler to redirect the first light beam into a second light guide as a second light beam in a second direction that is different from the first direction
Implementation Method 3
a diffraction grating to scatter or couple light out of the second light guide... diffractively couple out a portion of the second light beam
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
Dual light guide, grating-based backlighting redirects light guided in a first light guide in a first direction into a second light guide in a second direction of a grating-based backlight. A dual light guide, grating-based backlight includes the first light guide, the second light guide and a redirection coupler configured to redirect the guided light beam from the first light guide into the second light guide in the second direction. The dual light guide, grating-based backlight further includes a diffraction grating configured to diffractively couple out a portion of the redirected light beam from the second light guide as a coupled-out light beam directed away from a surface of the second light guide at a predetermined principal angular direction.