Light Guide Plate Separation Surfaces for Image Display Efficiency
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Solution Overview
Problem
Conventional image display apparatuses with light guide plates suffer from low light utilization efficiency due to a small effective area where light beams overlap at the observer's pupil, resulting in excessive unnecessary light generation.
Innovation Solution
The image display apparatus incorporates a light guide plate with a plurality of separation surfaces, where each surface separates incident light into reflected and transmitted components, with carefully set angle characteristics of reflectance to optimize light distribution and utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional light guide plate is used with a single exit portion, then the structure is simple, but the effective area where light beams overlap at the observer's pupil is small, resulting in low light utilization efficiency
Solution Approach 1:
The exit portion is divided into multiple exit portions (first exit portion and second exit portion) with different separation surfaces. Each exit portion extracts light at different incident angles, thereby increasing the effective area where light beams overlap at the observer's pupil and improving light utilization efficiency without significantly complicating the overall structure.
2Loss of energy
If multiple separation surfaces are added to increase light utilization efficiency, then light utilization efficiency improves, but the device complexity increases
Solution Approach 1:
Different separation surfaces are designed with different reflectance characteristics tailored to their specific functions. The first separation surface has high reflectance for extracting light at a first incident angle, while the second separation surface has high reflectance for extracting light at a second incident angle. This localized optimization allows efficient light extraction with minimal additional structure.
Solution Approach 2:
The patent optimizes specific parameters including the incident angle range (first incident angle range and second incident angle range), reflectance values (first reflectance and second reflectance), and the angular separation (difference between first incident angle and second incident angle). By carefully controlling these parameters, the patent achieves high light utilization efficiency while keeping the number of separation surfaces minimal.
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 achieves high light utilization efficiency and uniform luminance over the angle-of-field range incident on the observer's pupil, reducing unnecessary light and enhancing display performance.
Implementation Method 1
Each of the first separation surface and the second separation surface is configured to separate incident light into reflected light and transmitting light
Implementation Method 2
n is a refractive index of the light guide plate for light with a predetermined wavelength included in a band of the image light
Implementation Method 3
a light guide plate configured to guide a display image (light) to a pupil of an observer
Data Source
AI summary
An image display apparatus includes an image display element configured to emit image light, and a light guide plate that includes an entrance portion which the image light enters, and an exit portion from which the image light exits. The exit portion includes, in order from an entrance portion side, a first separation surface, and a second separation surface. Each of the first separation surface and the second separation surface is configured to separate incident light into reflected light and transmitting light. Predetermined inequalities are satisfied.