LED LIGHT SOURCES FOR IMAGE PROJECTION SYSTEMS
A light source for an image projection system comprises one or more LEDs packaged for high temperature operation. 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. Arrays of LED die are fabricated by the low temperature co-fired ceramic-on-metal technique (LTTC-M). The LEDs are mounted in an array of cavities having tapered sides to reflect light from the LEDs.
1 . A light source for an image projection system comprising:
a metal base having a first side and a second side;
one or more LED die disposed on the first side of the metal base;
a thermal connection pad disposed on a portion of the second side of the metal base;
a first layer disposed on a portion of the second side of the metal base;
a pair of electrical connection pads disposed on the first layer, the thermal connection pad further disposed between the pair of electrical connection pads, each LED die being thermally coupled through the metal base to the thermal connection pad, each LED die being electrically connected to the pair of electrical connection pads, the one or more LED die forming at least one red-emitting LED, at least one green-emitting LED and at least one blue-emitting LED.
2 . The light source of claim 1 , wherein at least one surface of each of the pair of electrical connection pads is coplanar with at least one surface of the thermal connection pad.
3 . The light source of claim 1 , wherein an LED die of the one or more LED die is electrically connected to an electrical connection pad of the pair of electrical connection pads by an electrical path including an insulated conducting via through the metal base.
4 . The light source of claim 1 , wherein an LED die of the one or more LED die is electrically connected to an electrical connection pad by an electrical path including the metal base.
5 . The light source of claim 1 , wherein the metal base has a thermal coefficient of expansion of about 6 ppm/degree C.
6 . The light source of claim 1 , wherein the metal base includes a concave region to reflect light and the one or more LED die is mounted overlying the concave region.
7 . The light source of claim 1 , further comprising a ceramic layer disposed on at least a portion of the first side of the metal base, the ceramic layer defining a cavity, the one or more LED die being disposed within the cavity.
8 . The light source of claim 7 , wherein the cavity has tapered sides to reflect light from the one or more LED die disposed within the cavity.
9 . The light source of claim 7 , wherein the one or more LED die is mounted on the ceramic layer overlying the metal base and is thermally coupled to the metal base by a thermal via through the ceramic coating.
10 . The light source of claim 1 , wherein the one or more LED die is electrically connected to an electrical connection pad by an electrical path including a bonding wire.
11 . The light source of claim 1 , wherein the red, green and blue LEDs are separately switchable.
12 . The light source of claim 1 , wherein the one or more LED die form at least one cyan-emitting LED.
13 . The light source of claim 1 , wherein the one or more LED die form at least one yellow-emitting LED.
14 . The light source of claim 1 , wherein the one or more LED die form at least one white-emitting LED.
15 . A light source for an image projection system comprising:
a metal base having a first side and a second side;
one or more LED die disposed on the first side of the metal base;
a thermal connection pad disposed on a portion of the second side of the metal base;
a first layer disposed on a portion of the second side of the metal base;
a pair of electrical connection pads disposed on the first layer, the thermal connection pad further disposed between the pair of electrical connection pads, each LED die being thermally coupled through the metal base to the thermal connection pad, each LED die being electrically connected to the pair of electrical connection pads, at least one surface of each of the pair of electrical connection pads is coplanar with at least one surface of the thermal connection pad, the one or more LED die forming at least one red-emitting LED, at least one green-emitting LED and at least one blue-emitting LED; and
an LED die of the one or more LED die being electrically connected to an electrical connection pad of the pair of electrical connection pads by an electrical path including an insulated conducting via through the metal base.
16 . The light source of claim 15 , wherein the metal base has a thermal coefficient of expansion of about 6 ppm/degree C.
17 . The light source of claim 15 , wherein the metal base includes a concave region to reflect light and the one or more LED die is mounted overlying the concave region.
18 . The light source of claim 15 , further comprising a ceramic layer disposed on at least a portion of the first side of the metal base, the ceramic layer defining a cavity, the one or more LED die being disposed within the cavity.
19 . The light source of claim 18 , wherein the cavity has tapered sides to reflect light from the one or more LED die disposed within the cavity.
20 . The light source of claim 18 , wherein the one or more LED die is mounted on the ceramic layer overlying the metal base and is thermally coupled to the metal base by a thermal via through the ceramic coating.