Switchable Optical Filter Light Source Control
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Solution Overview
Problem
Existing switchable materials for optical filters, such as photochromic, thermochromic, and electrochromic materials, face limitations in controllability, cost, optical clarity, and adaptability, particularly in environments with variable UV levels or temperatures, and require continuous electricity for maintenance of dark or faded states, which can interfere with display operations and generate excessive heat.
Innovation Solution
A switchable optical filter system comprising a layer of photochromic, thermochromic, or photochromic/electrochromic compounds, controlled by a light source providing specific wavelengths of light to transition between dark and faded states, with optional UV blocking and light dispersing layers, and a control mechanism to manage light transmittance efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If photochromic materials are used for automatic darkening, then the filtering action is passive and requires no user input, but the darkening reaction is inhibited in environments with low UV light (such as inside vehicles with UV-blocking windshields)
Solution Approach 1:
A UV-transparent layer is introduced as an intermediary between the photochromic material and the external environment. This layer allows UV light to reach the photochromic material while blocking UV light from passing through the final product, enabling the photochromic material to darken properly in vehicle applications where the windshield blocks UV
Solution Approach 2:
The optical filter is divided into functionally distinct layers: a photochromic material layer for light absorption and a UV-transparent layer for selective UV transmission. This segmentation allows each layer to perform its specific function optimally without interfering with the other
2Ease of operation
If electrochromic materials are used for controllable darkening, then the darkening and fading states can be controlled via electricity, but continuous application of electricity is required to maintain the dark or faded states
Solution Approach 1:
The system uses periodic or intermittent light sources to trigger photochromic darkening rather than continuous electrical power. The photochromic material darkens when exposed to light and maintains that state without continuous energy input, only requiring periodic light exposure to change states
Solution Approach 2:
The patent replaces electrochromic electrical control mechanisms with photochromic light-based control. Instead of using electricity to change the optical state, the system uses light exposure to trigger the photochromic reaction, eliminating the need for continuous electrical power
3Illumination intensity
If a light source is used to illuminate a display through a tinted glass, then the display becomes visible, but the luminance required may be substantial and generate excessive heat
Solution Approach 1:
The system changes the optical parameters of the glass dynamically. When display illumination is needed, the glass transitions from a highly tinted state to a more transparent state, allowing display light to pass through with minimal attenuation and reducing the heat generation from high-power illumination
4Ease of operation
If switchable materials are used for optical filtering, then controllable darkening is achieved, but the materials may have disadvantages such as cost, lack of optical clarity, reduced lifetime or haze
Solution Approach 1:
The patent uses a composite structure combining photochromic material with UV-transparent layers. This composite approach allows the photochromic material to provide controllable darkening while the UV-transparent layers maintain optical clarity and protect the photochromic material from degradation, extending its lifetime
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 provides controllable darkening and fading capabilities without continuous electricity, reduces power consumption and heat generation, and maintains optical clarity, making it suitable for various applications including displays and ophthalmic devices.
Implementation Method 1
Photochromic materials react to light levels by darkening in sunlight (or other light having a UV component), and spontaneously reverting to a faded state under low light conditions
Implementation Method 2
Thermochromic materials respond to temperature—when used as a window film, it may be useful in attenuating heat gain in a building under some conditions
Implementation Method 3
Electrochromic materials respond to application of electricity. Some electrochromic materials darken with application of a voltage, but fade passively when the application ceases
Data Source
AI summary
An apparatus is disclosed that includes a switchable optical filter having a layer of switchable material; a light source providing light of a wavelength that causes the switchable material to transition from a faded state to a dark state, or a dark state to a faded state; and a switch for controlling activation of the light source.