Thermally coupled light source for an image projection system

Abstract

In accordance with the invention a light source for an image projection system comprises one or more LEDs packaged for high temperature operation. Advantageously, the LED die are disposed on a package comprising a ceramic coated metal base including one or more underlying thermal connection pads, and underlying electrical connection pads, each LED die thermally coupled through the metal base to a thermal connection pad and electrically coupled to electrical connection pads. The LED can be mounted directly on the metal of the base or on a thin coating of electrical insulator on the metal. Arrays of LED die thus packaged are advantageously fabricated by the low temperature co-fired ceramic-on-metal technique (LTTC-M) and can be referred to as LTTC-M packaged arrays. The LEDs are advantageously mounted in an array of cavities having tapered sides to reflect light from the LEDs. The high temperature LED light sources can substitute for HID lamps in a variety of front and rear projection systems and displays. They are particularly useful for rear projection systems.

1 - 28 . (canceled)  
     
     
         29 . A light source for an image projection system comprising: 
 one or more LED die disposed on a ceramic-coated metal base coupled to a thermal connection pad and electrical connection pads, wherein each LED die is thermally coupled through the base to the thermal connection pad and electrically connected to the electrical connection pads.    
     
     
         30 . The light source of  claim 29  wherein the LED die are either mounted directly on the metal base or separated from the base by layer of electrically insulating and thermally conductive material having a thickness of  15  micrometers or less.  
     
     
         31 . The light source of  claim 29  wherein the metal base has a thermal coefficient of expansion of about 6 ppm/° C.  
     
     
         32 . The light source of  claim 29  wherein the ceramic coating includes a cavity and at least one LED is mounted in the cavity.  
     
     
         33 . The light source of  claim 32  wherein the cavity has tapered sides to reflect light from the LED die.  
     
     
         34 . The light source of  claim 29  wherein the metal base includes a concave region to reflect light and at least one LED die is mounted overlying the concave region.  
     
     
         35 . The light source of  claim 29  wherein the electrical connection pads and the thermal connection pad underly the metal base and are coplanar.  
     
     
         36 . The light source of  claim 29  wherein at least one LED die is mounted on the ceramic coating overlying the metal base and at least one LED die is thermally coupled to the metal base by a thermal via through the ceramic coating.  
     
     
         37 . The light source of  claim 29  wherein at least one LED die is electrically connected to an electrical connection pad by an electrical path including a bonding wire.  
     
     
         38 . The light source of  claim 29  wherein at least one LED is electrically connected to an electrical connection pad by an electrical path including an insulated conducting via through the metal base.  
     
     
         39 . The light source of  claim 29  wherein at least one LED is electrically connected to an electrical connection pad by an electrical path including the metal base.  
     
     
         40 . The light source of  claim 29  wherein the one or more LED die comprise a plurality of LED die disposed in an array overlying the metal base.  
     
     
         41 . The light source of  claim 29  wherein the one or more LED die form at least one red-emitting LED, at least one green-emitting LED and at least one blue-emitting LED.  
     
     
         42 . The light source of  claim 41  wherein the red, green and blue LEDs are separately switchable.  
     
     
         43 . The light source of  claim 41  wherein the one or more LED die form at least one cyan-emitting LED.  
     
     
         44 . The light source of  claim 41  wherein the one or more LED die form at least one yellow-emitting LED.  
     
     
         45 . The light source of  claim 41  wherein the one or more LED die form at least one white-emitting LED.