Video Display Apparatus Uniform Luminance Light Guide
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Solution Overview
Problem
Existing video display systems, such as head-mounted displays, often suffer from luminance unevenness due to the lack of consideration for the relationship between light beam intervals and flux diameter, leading to darker areas and non-uniform video presentation.
Innovation Solution
A video display apparatus employing a light guide plate with a video projection unit and a video light replication unit that replicates and distributes video light to maintain uniform luminance across the eye box, utilizing a light guide plate to transmit and expand the video light while ensuring consistent illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a beam splitter is used to split light flux and increase eye box width, then the eye box is enlarged, but luminance unevenness occurs due to improper relationship between light beam interval and flux diameter
Solution Approach 1:
The patent applies local quality by varying the reflectivity of different regions of the beam splitter. The beam splitter has a first region with higher reflectivity and a second region with lower reflectivity, allowing different parts of the light flux to be distributed with appropriate intensity. This resolves the luminance unevenness problem while maintaining the expanded eye box, as each region of the exit pupil receives optimized light distribution.
Solution Approach 2:
The patent changes the reflectivity parameter of the beam splitter across different regions. By making the reflectivity non-uniform (first region > second region), the system optimizes light distribution to achieve both wide eye box and uniform luminance. This parameter variation allows the beam splitter to compensate for the natural luminance drop at the edges of the expanded eye box.
2Area of stationary object
If light is transmitted through a light guide plate to expand eye box, then viewing area is increased, but dark areas appear due to insufficient consideration of light beam distribution
Solution Approach 1:
The beam splitter's non-uniform reflectivity distribution (first region with higher reflectivity, second region with lower reflectivity) ensures that light is distributed more intensely toward regions that would otherwise be darker in the expanded eye box. This local variation in optical property compensates for the luminance non-uniformity introduced by light guide plate transmission.
3Device complexity
If video light is replicated without considering flux diameter, then light distribution is simplified, but luminance unevenness occurs in displayed video
Solution Approach 1:
Rather than using complex multi-element optical systems to distribute light uniformly, the patent employs a beam splitter with spatially varying reflectivity. This single-component solution with local property variation achieves uniform luminance distribution while keeping the overall device complexity low.
Solution Approach 2:
The patent changes the reflectivity parameter across the beam splitter surface to achieve uniform luminance. This parameter variation approach provides a simple yet effective method for light distribution that avoids the need for complex optical designs while maintaining luminance uniformity.
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 provides a wide eye box with uniform luminance, ensuring that the user can view a video without dark areas, even when their eyes move, by replicating and distributing video light effectively through the light guide plate.
Implementation Method 1
an optical device including a light-transmitting substrate, optical means for coupling light into the substrate by total internal reflection
Data Source
AI summary
To provide a wide eye box and are capable of displaying a video having uniform luminance, it is provided a video display apparatus comprising: a video projection unit configured to project video light; a video light replication unit configured to replicate the video light; and a light guiding unit configured to transmit the video light through an inside of the light guiding unit, wherein the video light replication unit is configured to transmit the video light emitted from the video projection unit to the light guiding unit, wherein the light guiding unit is configured to transmit the video light that has entered through the inside to output the video light, and wherein the video light replication unit is configured to replicate the video light that has entered the video light replication unit so that a luminance distribution of the video light output from the light guiding unit is uniform.