Emissive highway markers

Abstract

A highway marker comprising an emissive device positioned on a highway, wherein said emissive device emits electromagnetic radiation.

What is claimed is:  
     
         1 . A highway marker comprising: 
 a housing;    a plurality of LED's mounted in the housing, emitting electromagnetic radiation;    a photodetector generating a signal responsive to an ambient light condition surrounding the housing; and    a control circuit responsive to the photodetector signal to control the electromagnetic radiation from at east one LED to emit radiation of a predetermined color as perceived by the human eye according to the spectral sensitivity of the human eye for the ambient light condition.    
     
     
         2 . A highway marker according to  claim 1 , further comprising a power source integral with the housing for powering the plurality of LED's.  
     
     
         3 . A highway marker according to  claim 1 , further comprising a cooling fin in thermal communication with at least one LED, wherein the cooling fin dissipates LED generated heat.  
     
     
         4 . A highway marker according to  claim 1 , further comprising a thermally conductive member for mounting the housing to a surface, wherein the thermally conductive member transfers heat between a surface and the marker.  
     
     
         5 . A highway marker according to  claim 1 , wherein at least one LED emits electromagnetic radiation in the range of 10 −2  m to 10 −8  m.  
     
     
         6 . A highway marker according to  claim 1 , wherein at least one LED emits electromagnetic radiation that is filtered with tinted material.  
     
     
         7 . A highway marker according to  claim 1 , wherein at least one LED has a substrate selected from silicon, gallium nitride, aluminum nitride, aluminum oxide, silicon carbide, diamond, silicon germanium, and germanium.  
     
     
         8 . A highway marker according to  claim 1 , further comprising a photovoltaic cell for generating power.  
     
     
         9 . A highway marker according to  claim 2 , wherein the power source is a battery.  
     
     
         10 . A highway marker according to  claim 2 , wherein the power source is a line power source.  
     
     
         11 . A highway marker according to  claim 1  further comprising a power source and wherein the plurality of LED's and the power source has a plurality of redundancies.  
     
     
         12 . A highway marker according to  claim 1  further comprising a battery to heat the housing.  
     
     
         13 . A highway marker according to  claim 1 , wherein the photodetector is responsive to electromagnetic radiation in the range of 10 −2  m to 10 −8  m.  
     
     
         14 . A highway marker according to  claim 1 , wherein the LED's transmit information regarding the location or traffic to vehicle-mounted detection systems that receive and process the signals.  
     
     
         15 . A highway marker according to  claim 1 , including an internal feedback providing a constant brightness of the LED's.  
     
     
         16 . A highway marker comprising: 
 a plurality of LED's;    a photodetector generating a signal responsive to ambient light condition; and    means for adjusting the wavelength of emitted electromagnetic radiation of at least one LED to maintain a predetermined color as perceived by the human eye according to the spectral sensitivity of the human eye for the ambient light condition.