Display Optical Cavity Light Recycling Aperture Segmentation
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Solution Overview
Problem
Mechanical light modulator displays face challenges in achieving a combination of speed, brightness, and low power consumption, with existing backlit displays struggling to efficiently direct and recycle light for improved optical efficiency.
Innovation Solution
The implementation of a display with an improved optical cavity, featuring a light guide with geometric light redirection centers, a reflective aperture layer, and a light injection system that includes a lamp and collimator to produce collimated light, along with MEMS-based or liquid-based light modulators, enhances light directivity and efficiency by recycling light through specular reflection and redirection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a backlight with reflective surfaces is used to recycle light, then optical efficiency is improved, but light directivity and brightness are reduced
Solution Approach 1:
The reflective aperture layer is segmented into multiple discrete apertures arranged in a specific pattern, allowing light to be redirected through multiple paths while maintaining directivity. This segmentation enables the system to achieve both high optical efficiency through light recycling and good brightness through controlled light emission paths.
Solution Approach 2:
The patent introduces a temporal dimension to light recycling by using sequentially operating light modulators that switch between different aperture groups. This temporal multiplexing allows the system to recycle light across multiple time cycles while maintaining high brightness during each display cycle, effectively resolving the contradiction between efficiency and brightness.
2Speed
If mechanical light modulators are used, then speed and viewing angles are improved, but power consumption increases
Solution Approach 1:
The light modulators operate in periodic cycles, sequentially switching between different aperture groups rather than continuously operating. This periodic operation allows the backlight to recycle light during non-display cycles while the modulators remain in low-power states, significantly reducing overall power consumption while maintaining high display speed during active cycles.
Solution Approach 2:
The optical cavity and reflective surfaces are pre-configured to recycle light before it reaches the modulators. This preliminary light recycling reduces the burden on the modulators to generate sufficient brightness, allowing them to operate at lower power levels while maintaining high display speed through their fast switching capability.
3Device complexity
If aperture area ratio is reduced to 8-20%, then device complexity is reduced, but optical throughput efficiency decreases
Solution Approach 1:
The optical cavity creates continuous light recycling paths that repeatedly redirect light through the apertures over multiple cycles. This continuity compensates for the small aperture area ratio by ensuring that light is not wasted but continuously reused, maintaining high optical throughput efficiency despite the simplified aperture structure with only 8-20% area ratio.
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
This approach significantly increases optical throughput, allowing for higher brightness with reduced power consumption, as demonstrated by improved conical reflectance and recycling efficiency, directing a higher percentage of light towards the viewer within favorable angles.
Implementation Method 1
a structure was disclosed for improving the optical efficiency of a display including an array of apertures—by forming such apertures or light transmissive regions as part of an otherwise reflective surface (referred to as a 'reflective aperture layer'). This reflective aperture layer, when coupled with a backlight that includes a second reflective surface, forms an optical cavity that allows for the recycling of light rays that do not immediately pass through the apertures.
Implementation Method 2
The light guide includes a plurality of geometric light redirection centers to extract light from the backlight. Various embodiments of such redirection centers are described in U.S. Pat. Nos. 5,005,108; 5,202,950; 5,884,872; 6,079,838; 6,174,064; 6,731,355; 6,827,456; 7,014,349; and 7,046,905, the entireties of which are herein incorporated by reference.
Implementation Method 3
the display includes a light injection system including a lamp and a light collimator for introducing a non-random fraction of light output by the lamp into the light guide to produce collimated light within a predetermined range of angles.
Data Source
AI summary
A display includes an array of light modulators that define a display plane, a light guide and front- and rear-facing reflective surfaces. The light guide includes a plurality of geometric light redirectors, and at least 50% of the light guide's rear surface is parallel to the display plane. The rear-facing reflective surface is parallel to the display plane and includes a plurality of apertures.