Grating Collimator Light Recycling for Backlight Illumination
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Solution Overview
Problem
Passive electronic displays, which do not emit light, face limitations in practical applications due to their inability to emit light, necessitating coupling with external light sources, such as backlights, to function as active displays.
Innovation Solution
A grating collimator system comprising a light guide, a light-recycling light source, and a diffraction grating coupler that provides collimated illumination to a backlight, enabling the display to emit light and function as an active display, suitable for both 2D and 3D or multiview displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If passive displays are coupled with external light sources to enable light emission, then the display can function as an active display, but the device complexity and power consumption increase
Solution Approach 1:
The patent combines the light source, light guide, and display elements into an integrated structure where the light-emitting diode is directly coupled with the light guide and display substrate. This merging eliminates the need for separate external backlight assemblies and complex optical coupling mechanisms, thereby enabling light emission while reducing overall device complexity
Solution Approach 2:
The light guide serves multiple functions simultaneously: it guides light from the LED, provides structural support, and acts as part of the display element substrate. This multi-functionality reduces the number of separate components needed, allowing the display to achieve active display functionality without proportionally increasing device complexity
2Illumination intensity
If external light sources are coupled to passive displays, then light emission is enabled, but power consumption increases
Solution Approach 1:
The light guide is designed to efficiently guide and distribute light generated by the integrated LED throughout the display structure. This self-service light guiding mechanism maximizes the utilization of light produced by the single LED source, eliminating the need for additional power-hungry external backlight units while maintaining effective light emission across the display
Solution Approach 2:
The integrated design ensures continuous and efficient light transmission from the LED through the light guide to the display elements. This continuous useful action minimizes light loss and maximizes the effectiveness of each photon generated, thereby reducing the total power required to achieve the desired illumination intensity compared to systems with separate external light sources
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 grating collimator system enhances the backlight's ability to provide directional or diffuse illumination, improving the display's performance by recycling and augmenting light, allowing for effective light emission without the need for external light sources in some configurations.
Implementation Method 1
The diffraction grating is at a guiding surface of the light guide and is configured to diffractively redirect the light provided by the light-recycling light source into the light guide as the guided light at the non-zero propagation angle
Implementation Method 2
The light guide is configured to guide light as guided light at a non-zero propagation angle relative to a plane of a guiding surface of the light guide
Data Source
AI summary
A grating collimator and backlight system provide collimated light to illuminate a backlight. The grating collimator includes a light guide configured to guide light as guided light and a light-recycling light source configured to provide light to the light guide and to recycle light received from the light guide. The grating collimator further includes a diffraction grating coupler configured to diffractively redirect the provided light into the light guide as the guided light. The backlight system includes the grating collimator configured to provide collimated output light and the backlight configured to receive the collimated output light. The backlight may be multiview backlight.