Sawtooth Light Guide Optics for Wider View and Stray Light Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing display devices suffer from stray light entering the observer's eyes due to external light being incident on the light guide and exiting again, causing interference with the intended image.
Innovation Solution
The display device employs a first light guide with a reflective surface and a second light guide with a sawtooth structure, combined with a beam splitter, where the second light guide's sawtooth surface absorbs or shields external light, and the beam splitter repeatedly transmits and reflects light to enlarge the visible image range while suppressing stray light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a light guide with a flat plate and beam splitters is used to enlarge the visible range, then the luminous flux is expanded and the visible range is enlarged, but stray light from external sources enters the light guide and exits again, causing interference to the observer
Solution Approach 1:
The light guide is divided into multiple light guide layers (first light guide layer, second light guide layer, third light guide layer) with beam splitters positioned at different depths. This segmentation allows the system to expand the visible range through multiple extraction points while the reflective surface on the third light guide layer redirects external stray light away from the extraction surfaces, preventing interference.
Solution Approach 2:
A reflective surface (fourth surface) is introduced as an intermediary element on the third light guide layer. This reflective surface acts as a mediator that intercepts external light entering the light guide and redirects it at a specific angle away from the beam splitter extraction paths, thereby preventing stray light from reaching the observer while maintaining the light extraction function.
2Area of stationary object
If multiple beam splitters are used to extract light at different positions, then the luminous flux is enlarged and visibility is improved, but the device complexity increases
Solution Approach 1:
Multiple light guide layers with beam splitters are merged into a single integrated optical assembly. The first, second, and third light guide layers are positioned adjacently with their respective beam splitters, creating a unified structure that expands the visible range through coordinated light extraction at multiple positions without requiring separate optical systems.
Solution Approach 2:
Each light guide layer serves multiple functions: the first light guide layer extracts light through its beam splitter, the second light guide layer provides additional extraction points, and the third light guide layer with its reflective surface both extracts light and redirects stray light. This multi-functionality reduces the need for additional dedicated components.
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 solution effectively suppresses stray light and enlarges the visible image range by using a beam splitter and a sawtooth surface to manage light transmission and reflection, enhancing image visibility and reducing shadows.
Implementation Method 1
a beam splitter configured to transmit a part of the light and reflect the remainder of the light
Implementation Method 2
a reflective surface that reflects the light incident from the collimator in a predetermined direction and a plurality of beam splitters translucent to visible light. This display device is set such that the luminous flux introduced into the light guide is reflected at the interface between the flat plate and the outside in a direction satisfying the toral reflection condition
Implementation Method 3
the second surface is configured to shield or dim visible light... At the second surface, absorption, reflection, diffusion, dimming, etc., of the light occur. Therefore, it is possible to suppress stray light
Data Source
Figure 1~2
Figure 3~4
AI summary
A display device 1 includes: an image display element 11 configured to display an image to be displayed; a collimator 12 configured to convert light emitted from each point on the image displayed on the image display element 11 into collimated light; a first light guide 131 formed of a flat plate made of a first material transparent to the light; a second light guide 132 formed of a plate member made of a second material transparent to the light, the second light guide having one surface and the other surface, the one surface of the second light guide being a flat surface in contact with one of surfaces of the flat plate of the first light guide, the other surface of the second light guide being a sawtooth surface 1320; and a beam splitter 133 formed on an interface between the first light guide 131 and the flat surface of the second light guide 132, the beam splitter being configured to transmit a part of the light and reflect the remainder of the light, wherein the sawtooth surface 1320 of the second light guide is configured by alternately combining a first surface 1321 and a second surface 1322, the first surface 1321 being non-parallel to a propagating direction of the light propagating through the second light guide after passing through the interface and being configured to transmit the light, the second surface 1322 being substantially parallel to the propagating direction.