Photochromic Optical Element for Variable Tinting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing glass windows with variable tinting and transparency, known as LC glasses, require costly conductive and transparent electrode layers for electrical activation, making them expensive for large-area applications.
Innovation Solution
An optical element comprising a light guide plate with a matrix material transparent to ultraviolet light and embedded scattering centers, combined with filter layers opaque to ultraviolet light and photochromic layers whose transparency to visible light is variable by ultraviolet light, allowing for adjustable tinting without the need for conductive layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If liquid crystal electrode layers are used to achieve variable transparency, then the transparency can be electrically controlled, but the production costs increase significantly
Solution Approach 1:
The patent removes the expensive conductive electrode layers from the system entirely. Instead of using liquid crystals between electrodes, the invention uses a light guide plate with phosphors that convert UV light to visible light, combined with photochromic materials that change transparency in response to UV exposure. This extraction of the electrode system eliminates the associated high costs while maintaining variable transparency control through a different mechanism.
Solution Approach 2:
The patent replaces the electrical control mechanism (electrodes applying electric fields to liquid crystals) with an optical control mechanism (UV light triggering photochromic materials). The light guide plate distributes UV light across the surface, and the photochromic materials respond to this optical stimulus by changing their transparency, substituting the electrical field-based control with light-based control.
2Area of stationary object
If large-area glass windows with variable transparency are produced, then the application scope increases, but the cost with electrode layers becomes prohibitive
Solution Approach 1:
The patent employs materials and structures that are inherently cheaper for large-area production. The light guide plate can be made from standard acrylic or polycarbonate sheets, the phosphors are applied as simple coatings, and the photochromic materials can be incorporated as layers or coatings. These components are much more cost-effective for large-area applications compared to transparent conductive oxide electrodes, enabling economical production of large windows.
Solution Approach 2:
The patent changes the fundamental operating parameters of the system. Instead of electrical parameters (voltage, current) required by liquid crystal electrodes, the system uses optical parameters (UV light intensity, wavelength) to control transparency. This parameter change enables the use of simpler, cheaper materials that can be manufactured in large areas without the cost constraints of electrode-based systems.
3Ease of manufacture
If photochromic layers are used instead of electrode layers, then the material cost decreases, but the transparency control mechanism changes from electrical to optical
Solution Approach 1:
The light guide plate serves multiple functions: it guides and distributes UV light across the surface, it acts as a structural support for the photochromic materials, and it provides the optical path for both the activating UV light and the visible light that passes through the variable transparency region. This multi-functionality reduces the need for separate control components, simplifying the overall system despite the change from electrical to optical control.
Solution Approach 2:
The photochromic materials automatically respond to UV light exposure by changing their transparency state without requiring external electrical control. The system self-regulates based on the UV light intensity received, with the light guide plate naturally distributing the UV light across the surface. This self-service characteristic eliminates the need for complex electrical control circuits while maintaining effective transparency control.
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 provides a cost-effective and continuously tintable optical element that can be used in large areas, achieving minimal influence on visible light transparency while allowing significant scatter in the ultraviolet range, thus reducing costs compared to traditional LC glasses.
Implementation Method 1
a first photochromic layer at least on the first major surface, between the light guide plate and the first filter layer, with a transparency to visible light variable by ultraviolet light
Implementation Method 2
a light guide plate with a first major surface and a second major surface opposite the first major surface... at least one light-emitting semiconductor device that couples ultraviolet light into the light guide plate via a side face
Implementation Method 3
the light guide plate includes a matrix material transparent to ultraviolet light in which scattering centers are embedded
Data Source
AI summary
An optical element includes a light guide plate with a first major surface and with a second major surface opposite the first major surface and with side faces connecting the first and second major surfaces, wherein the light guide plate includes a matrix material transparent to ultraviolet light in which scattering centers are embedded, at least one light-emitting semiconductor device that couples ultraviolet light into the light guide plate via a side face when in operation, a first filter layer on the first major surface and a second filter layer on the second major surface, wherein the filter layers opaque to ultraviolet light and at least partially transparent to visible light, and a first photochromic layer at least on the first major surface, between the light guide panel and the first filter layer, with a transparency to visible light by ultraviolet light.