Light Guide Plate Deflecting Members for Uniform Display Brightness
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Solution Overview
Problem
Existing image display apparatuses suffer from brightness unevenness and color unevenness when the observer's eye position changes, due to inadequate light emission and reduced light intensity in certain regions, leading to suboptimal viewing experiences.
Innovation Solution
The implementation of an image display apparatus with a collimating optical system and an optical device featuring a light guide plate, first deflecting means for total reflection, and second deflecting means for multiple reflections, ensuring that light is evenly distributed and emitted across a wider angle of view without increasing the light guide plate's thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional optical device with simple light guiding is used, then the device structure is simple, but brightness unevenness and color unevenness occur when the observer's eye position changes
Solution Approach 1:
The optical device is segmented into multiple functional components: a light guide plate for light propagation, first deflecting means for total internal reflection, and second deflecting means for controlled light emission. This segmentation allows each component to optimize its function, resolving the contradiction between structural simplicity and brightness uniformity.
Solution Approach 2:
Different regions of the optical device are assigned different optical properties. The light guide plate has specific refractive indices in different directions (nx, ny, nz), and the deflecting means are positioned at specific locations to control light emission angles. This local differentiation ensures uniform brightness across various viewing positions while maintaining overall structural efficiency.
2Illumination intensity
If the light guide plate thickness is increased to improve light distribution, then brightness uniformity improves, but the device size increases
Solution Approach 1:
The patent changes the optical parameters of the light guide plate by introducing anisotropic refractive indices (nx, ny, nz) and controlling the incident light angles within specific ranges. This allows effective light distribution with a compact plate thickness, resolving the contradiction between light uniformity and device thickness.
Solution Approach 2:
Instead of increasing thickness in one dimension, the patent uses angular control in the optical domain to achieve light redistribution. The first and second deflecting means redirect light at specific angles, achieving uniform emission without increasing the physical thickness of the light guide plate.
3Adaptability or versatility
If the viewing angle range is expanded, then the observer can view the image from more positions, but brightness and color unevenness increase
Solution Approach 1:
The optical device dynamically adapts to different viewing angles through its deflecting means. As the observer's eye position changes, the first and second deflecting means continuously redirect light at appropriate angles, maintaining brightness and color uniformity across a wide viewing range.
Solution Approach 2:
The optical device is designed to serve multiple viewing positions simultaneously. The light guide plate and deflecting means work together to emit light uniformly in multiple directions, making the display accessible from various angles while maintaining consistent image quality.
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 significantly reduces brightness and color unevenness, providing a consistent and high-quality display experience regardless of the observer's eye position, by ensuring that light is uniformly emitted and viewed across a broader range.
Implementation Method 1
a light guide plate 721 (121 in FIG. 1), a first optical member 730 (130 in FIG. 1, for example, formed by a single-layer light reflective film), and a second optical member 740 (140 in FIG. 1, for example, formed by a light reflective multilayer film having a layered structure. Incident light propagates in the light guide plate 721 by total reflection and is then emitted from the light guide plate 721.
Implementation Method 2
The first optical member 730 reflects the light incident on the light guide plate 721 so that the incident light is totally reflected in the light guide plate 721
Implementation Method 3
the second optical member 740 emits the light, which propagates in the light guide plate 721 by total reflection, from the light guide plate 721
Data Source
AI summary
An image display apparatus includes an image forming device, a collimating optical system, and an optical device. The optical device includes a light guide plate, a first deflecting member that deflects light incident on the light guide plate, and a second deflecting member that deflects the light, which propagates in the light guide plate by total reflection, a plurality of times. The first and second deflecting members are provided in the light guide plate. Light having one wavelength emitted from at least one pixel satisfies the following condition:2t·sin θ−2≤WY≤2t·sin θ+2where an axial direction of the light guide plate is the Y-direction, WY prepresents the width in the Y-direction of the light incident on the light guide plate, t represents the thickness of the light guide plate, and θ represents the total reflection angle.