Variable Transmittance Optical Filter with Dual-State Switching
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Solution Overview
Problem
Current optical filters, such as photochromics, electrochromics, liquid crystals, and suspended particle displays, face limitations in transitioning between light and dark states efficiently, particularly in responding to UV radiation and requiring external power for control, which affects their practicality in applications like windows and ophthalmic devices.
Innovation Solution
A variable transmittance optical filter is developed, comprising two transparent substrates with electrodes and a switching material having both electrochromic and photochromic properties, allowing it to automatically darken with UV exposure and lighten with an applied electric voltage, eliminating the need for constant power to maintain the dark state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If photochromic compounds are used in optical filters, then automatic darkening in sunlight is achieved, but reversion to light state is slow and cannot be controlled manually
Solution Approach 1:
The patent combines photochromic and electrochromic technologies into a single optical filter system. The photochromic layer provides automatic darkening in sunlight, while the electrochromic layer with transparent electrodes enables manual control through applied voltage, allowing the filter to transition between states on demand.
Solution Approach 2:
The patent introduces transparent conducting oxide electrodes as an intermediary between the user's control input and the chromogenic materials. These electrodes apply electrical fields to the electrochromic layer, enabling manual switching while remaining visually transparent and not interfering with the optical properties of the filter.
2Ease of operation
If photochromic devices are used with user control through electronics, then manual control is achieved, but power is required to maintain the dark state
Solution Approach 1:
The electrochromic layer transitions to and maintains its dark state through periodic or pulsed voltage application rather than continuous power supply. Once the electrochromic material is in the desired state, minimal or no power is needed to maintain it, reducing overall energy consumption while preserving manual control capability.
3Ease of operation
If electrochromic technology is used, then dynamic alteration of light transmission through electricity is achieved, but external electrical power is required to darken
Solution Approach 1:
The patent merges electrochromic technology with photochromic technology, where the electrochromic component provides dynamic control capability. When combined with the photochromic layer that automatically responds to UV light, the system achieves both manual controllability and automatic response without requiring continuous external power for the entire system.
4Extent of automation
If photochromic compounds are exposed to UV light, then automatic darkening is achieved, but the compounds break down on prolonged exposure
Solution Approach 1:
The patent uses composite material structures where photochromic and electrochromic materials are combined in a single device. The electrochromic component can be activated by electrical fields that do not require UV exposure, providing an alternative switching mechanism that avoids UV-induced degradation of the photochromic compounds while maintaining the benefits of both material types.
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 solution enables rapid, energy-efficient switching between light and dark states, reducing glare and solar heat gain while maintaining clarity and occupant comfort, with low manufacturing costs and compatibility with various substrates, suitable for architectural, automotive, and ophthalmic applications.
Implementation Method 1
capable of transitioning from a light state to a dark state on exposure to UV radiation
Implementation Method 2
from a dark state to a light state with application of an electric voltage
Data Source
AI summary
Variable transmittance optical filters capable of transitioning from a light state to a dark state on exposure to UV radiation and from a dark state to a light state with application of an electric voltage are provided. The optical filters comprise a switching material that comprises one or more chromophores that have electrochromic and photochromic properties.