Thermally switched optical downconverting filter

Abstract

A thermally switched optical downconverting (TSOD) filter is a self-regulating device including a downconverter that converts incoming light at a variety of wavelengths into longer-wavelength radiation and then directs it using one or more bandblock filters in either the inward or outward direction, depending on the temperature of the device. This control over the flow of radiant energy occurs independently of the thermal conductivity or insulating properties of the device and may or may not preserve the image and color properties of incoming visible light. The TSOD filter is energy-efficient as it can be used to regulate the internal temperature and illumination of buildings, vehicles, and other structures without the need for an external power supply or operator signals. The TSOD filter has unique aesthetic and optical properties not found in traditional windows, skylights, stained glass, light fixtures, glass blocks, bricks, or walls.

What is claimed is: 
     
         1 . A reflective film for regulating the reflection of incident radiant energy comprising
 a first layer of a distributed Bragg reflector; and   a second layer of temperature-responsive optical material, wherein   above a threshold temperature down to 0% of incident radiant energy is transmitted by the film, and   below the threshold temperature up to 100% of the incident radiant energy is transmitted by the film;   at a first temperature a first percentage of the incident radiant energy is reflected from the film and a second percentage of the incident radiant energy is transmitted through the film; and   at a second temperature a third percentage of the incident radiant energy is reflected from the film and a fourth percentage of the incident radiant energy is transmitted through the film.   
     
     
         2 . A method for regulating reflection and transmission of radiant energy comprising
 orienting a first layer of a distributed Bragg reflector crosswise with a second layer of a temperature-responsive optical material;   reflecting up to 100% of incident radiant energy with the first and second layers when above a threshold temperature; and   wherein when below a threshold temperature the first and second layers cease to reflect below the threshold temperature,   transmitting up to 100% of the incident radiant energy.   
     
     
         3 . A method for regulating an internal temperature of a buildings, a vehicle, or other structure comprising
 placing a temperature-responsive optical film on an exterior of a structure; and   inverting a temperature response of the temperature-responsive optical film whereby the temperature-responsive optical film is primarily reflective of incident radiant energy at high temperatures and comparatively more transparent to, absorbent of, or both, incident radiant energy at low temperatures.   
     
     
         4 . The method of  claim 3  further comprising positioning the temperature-responsive optical film on the structure to receive maximum incident radiant energy at cold temperatures or in the winter season and to receive minimum incident radiant energy at high temperatures or in the summer season.