Light Guide Polarization Control for Uniform AR Image Expansion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image display devices for virtual reality and mixed reality suffer from luminance unevenness and variation in image quality when the observer moves their eyes within the viewing region.
Innovation Solution
The image display device incorporates a light guide with a pair of principal surfaces and includes an incident region for diffracting image light to propagate inside the guide and an expansion region for emitting diffracted image light as multiple beams. A polarization adjuster sets the image light to a specific polarization state, ensuring the propagated light has a stable polarization state in the expansion region, which reduces diffraction efficiency variation and luminance unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the light guide uses diffraction structures to expand the pupil and guide image light, then the viewing region and image guidance capability are improved, but luminance unevenness and image quality variation occur when the observer moves their eyes
Solution Approach 1:
The patent applies parameter changes by controlling the polarization state of light as a physical parameter. By setting the incident light to a specific polarization state (second polarization state) that differs from the propagated light's polarization state (first polarization state), the patent optimizes diffraction efficiency in the expansion region. This parameter control ensures uniform luminance and image quality across the viewing region, resolving the contradiction between expanded viewing area and image quality uniformity.
2Adaptability or versatility
If the diffraction structure expands the optical beam to multiple positions, then the pupil expansion and viewing flexibility are improved, but diffraction efficiency variation and luminance unevenness increase
Solution Approach 1:
The patent changes the polarization state parameter of light to resolve diffraction efficiency variation. By configuring the incident light with a second polarization state that is different from the first polarization state of the propagated light, the patent achieves stable and uniform diffraction efficiency across multiple expansion positions. This ensures reliable and consistent luminance distribution while maintaining viewing flexibility.
3Device complexity
If the polarization state of propagated light is not controlled, then the optical system remains simple, but luminance unevenness and image quality variation occur
Solution Approach 1:
The patent introduces polarization state control as a parameter management approach. By setting the incident light to have a second polarization state that differs from the propagated light's first polarization state, the patent achieves uniform luminance distribution without adding complex optical components. This parameter-based solution maintains relative system simplicity while effectively resolving luminance unevenness.
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 configuration effectively suppresses the variation in image quality by stabilizing the polarization state of the propagated light, thereby reducing luminance unevenness and enhancing the overall image display quality.
Implementation Method 1
an incident region configured to diffract the image light to propagate inside the light guide by reflection between the pair of principal surfaces
Implementation Method 2
diffract the image light to propagate inside the light guide by reflection between the pair of principal surfaces
Implementation Method 3
an expansion region configured to diffract the propagated image light to emit the diffracted image light as a plurality of beams of image light from a plurality of positions
Implementation Method 4
The image light propagated to the expansion region has a first polarization state by setting the image light incident on the incident region to have a second polarization state
Data Source
AI summary
An image display device for causing an optical image to be visible including: a display to emit image light; and a light guide to guide the image light from the display to an outside. The light guide has principal surfaces, including: an incident region to diffract the image to propagate inside the light guide by reflection between principal surfaces, in response to incidence of the image light from the display; and an expansion region to diffract the propagated image light to emit the diffracted image light as beams of image light from positions. The image light propagated to the expansion region has a first polarization state polarized along a direction parallel or perpendicular to a plane including a normal direction in the expansion region and a propagation direction by setting the image light incident on the incident region to have a second polarization state different from the first polarization state.