Optical Member Geometry for Uniform Virtual Display Illumination
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Solution Overview
Problem
Existing optical systems suffer from brightness unevenness when used in virtual image display devices, particularly due to the use of TIR lens arrays that fail to uniformly distribute illumination light.
Innovation Solution
An optical member comprising light control units with specific geometric configurations, including convex emitting surfaces, curved first incident surfaces, and inclined reflective surfaces, which are designed to improve light distribution uniformity by reducing brightness unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a TIR lens array is used to focus illumination light, then the light can be directed toward the image forming unit, but brightness unevenness occurs in the emitted light
Solution Approach 1:
The optical member is divided into multiple light control units arranged in an array, with each unit independently controlling light from a corresponding light source. This segmentation allows precise control of light distribution from each source while maintaining overall uniformity across the entire array.
Solution Approach 2:
Each light control unit has specifically designed optical surfaces (convex emitting surface, curved first incident surface, and inclined reflective surface) tailored to control light from its corresponding light source. The local geometric configuration optimizes light distribution for each individual unit, addressing brightness unevenness locally while contributing to global uniformity.
2Illumination intensity
If the first incident surface is made convex with larger radius of curvature, then light distribution uniformity improves, but the device complexity increases
Solution Approach 1:
The first incident surface is designed as a convex curved surface with a specific radius of curvature that is larger than that of the emitting surface. This curvature is essential for redirecting light rays and achieving uniform light distribution. The convex shape with controlled curvature radius optimizes the optical path while maintaining manufacturability.
Solution Approach 2:
The optical design carefully controls specific parameters including the radius of curvature of the first incident surface (making it larger than the emitting surface), the inclination angle of the reflective surface, and the geometric dimensions of the light control units. These parameter optimizations achieve uniform light distribution while keeping the device complexity manageable.
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 optical member enhances light uniformity and reduces brightness disparities, improving the overall illumination quality in virtual image display devices.
Implementation Method 1
the first incident surface is a convex surface curved in a direction away from the emitting surface
Implementation Method 2
a reflective surface located at an outer periphery of the second incident surface in a top view, and inclined in a direction away from a center of the light control unit
Data Source
AI summary
An optical member includes: a plurality of light control units, each including: an upper surface serving as an emitting surface, a first incident surface located below the emitting surface, a second incident surface located at an outer periphery of the first incident surface in a top view, and extending downward from a first incident surface side, and a reflective surface located at an outer periphery of the second incident surface in the top view, and inclined in a direction away from a center of the light control unit so as to extend closer to the emitting surface from a vicinity of the second incident surface. The light control units are configured such that light incident on the first incident surface and the second incident surface, and light reflected by the reflective surface are emitted from the emitting surface.