Lightguide Display System with Reflective Layers for 3D Stacked Images
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Solution Overview
Problem
Existing display systems using lightguides with reflective layers struggle to effectively extract and project images or patterns due to limited light transmission and reflection, resulting in decreased brightness and clarity along the thickness direction, especially when stacked images are displayed.
Innovation Solution
A display system comprising a lightguide sandwiched between reflective layers with high specular reflectance and controlled transmittance, where the light extraction pattern allows light to exit through major surfaces, enabling multiple reflections and transmissions to create three-dimensional stacked images with varying brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reflective layers with high specular reflectance are used, then light extraction efficiency is improved, but brightness along the thickness direction decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the optical properties of reflective layers. Specifically, it uses a first reflective layer with 60-80% specular reflectance and a second reflective layer with 80-90% specular reflectance, along with controlling their transmittance properties to achieve optimal light extraction while maintaining brightness distribution.
Solution Approach 2:
The patent implements local quality by assigning different optical characteristics to different reflective layers. The first reflective layer (closer to light source) has lower reflectance (60-80%) and higher transmittance, while the second reflective layer has higher reflectance (80-90%) and lower transmittance, creating optimized local light management at each interface.
2Adaptability or versatility
If multiple stacked images are displayed, then three-dimensional effect is improved, but brightness uniformity deteriorates
Solution Approach 1:
The patent uses parameter changes to control brightness distribution across stacked images by adjusting the transmittance and reflectance of each reflective layer, allowing the brightest image to be positioned at the desired location while maintaining visibility of other stacked images.
Solution Approach 2:
The patent applies asymmetry by creating intentional brightness variation among stacked images, with one image designated as the brightest. This asymmetric brightness distribution enhances the three-dimensional effect and allows selective emphasis of specific images within the stack.
3Length of moving object
If lightguide thickness is increased, then light propagation distance is improved, but light extraction efficiency deteriorates
Solution Approach 1:
The patent introduces reflective layers as intermediary elements between the light source and the external environment. These layers mediate light propagation by reflecting light back into the lightguide multiple times, enabling extended propagation distance while maintaining extraction efficiency through controlled reflection and re-extraction cycles.
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 system achieves a hall of mirrors effect, producing a three-dimensional pattern with a high brightness at the top that decreases along the thickness direction, enhancing image visibility and creating a continuous tube-like structure from the lightguide.
Implementation Method 1
light extraction pattern for extracting light that would otherwise be confined and propagate within the lightguide primarily by total internal reflection
Implementation Method 2
The first and second reflective layers are disposed on opposite sides of the lightguide adjacent the respective first and second major surfaces of the lightguide. An average specular reflectance of each of the first and second reflective layers is at least 50% in a predetermined wavelength range.
Data Source
AI summary
A display system including a lightguide and first and second reflective layers disposed on opposite sides of the lightguide is provided. The lightguide has opposing first and second major surfaces and includes a light extraction pattern for extracting light that would otherwise be confined and propagate within the lightguide primarily by total internal reflection. Light extracted by the light extraction pattern exits the lightguide through at least one of the first and second major surfaces of the lightguide. Each of the first and second reflective layers has an average specular reflectance of at least 50% in a predetermined wavelength range. The light extraction pattern may be repeatedly imaged by the first and second reflective layers to produce three-dimensional stacked images of the light extraction pattern.