Light Guide Device With Position-Dependent Partial Reflection Angles
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Solution Overview
Problem
In light guide devices used in display apparatuses, the intensity of light beams reflected by partial reflection surfaces is reduced due to varying incident angles, leading to decreased brightness when observed.
Innovation Solution
A light guide device configuration with partial reflection surfaces inclined at different angles along the light guide portion, where the incident angle range of surfaces on one end is set to be larger than those on the other end, optimizing reflectance in the visible light wavelength region to enhance light beam intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a plurality of obliquely-inclined half mirrors are provided in parallel between two flat surfaces to guide light beams, then light guidance function is achieved, but incident angle dependence causes reflectance variation and brightness reduction
Solution Approach 1:
The patent applies local quality by setting different appropriate incident angle ranges for different positions along the light guide portion. Specifically, the partial reflection surfaces are configured such that those on the one end side have a larger appropriate incident angle range than those on the other end side. This positional differentiation compensates for the incident angle dependence of reflectance, ensuring that light beams incident from the light-emitting portion fall within the appropriate incident angle range for each position, thereby maintaining consistent reflectance and brightness throughout the light guide portion.
2Ease of manufacture
If partial reflection surfaces are inclined at the same angle throughout the light guide portion, then manufacturing is simplified, but light beam intensity varies due to different incident angles at different positions
Solution Approach 1:
The patent implements local quality by configuring partial reflection surfaces with position-dependent inclination angles. The partial reflection surfaces on the one end side of the light guide portion are inclined at angles that provide a larger appropriate incident angle range, while those on the other end side have smaller angles. This localized variation in inclination angle ensures that light beams maintain appropriate incident angles at each position, preserving light beam intensity while allowing for controlled manufacturing complexity.
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 increases the intensity of light beams reflected by partial reflection surfaces, resulting in higher brightness and improved image recognition for the observer.
Implementation Method 1
a plurality of partial reflection surfaces that are disposed along the first direction between the first surface and the second surface and are inclined at the same angle from a normal direction with respect to the second surface toward the one end side
Data Source
AI summary
A light guide device used in a display apparatus includes a transparent light guide portion that guides light beams incident from one end side to a light-emitting portion. The light guide portion includes a plurality of partial reflection surfaces between a first surface and a second surface which are parallel to each other, the plurality of partial reflection surfaces being inclined at the same angle from a normal direction with respect to the second surface toward the one end side. In the plurality of partial reflection surfaces, an appropriate incident angle range of the partial reflection surface positioned on the one end side is set to a larger angle than that of the partial reflection surface positioned on another end side.