High efficacy white LED
AssigneeCree, Inc.
InventorJames Ibbetson
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Abstract
A white light emitting solid-state lamp is disclosed having an output of at least 75 lumens per watt at 20 milliamps drive current. The lamp includes a light emitting diode, an encapsulant, and a header. The diode includes a conductive silicon carbide substrate for electrical contact and a Group III nitride active portion on the silicon carbide substrate for generating desired frequency photons under the application of current across the diode. The header includes a reflective cup for supporting the diode and for providing electrical contact to the diode and to the active portion. The encapsulant includes a phosphor, present in at least portions of the encapsulant for generating responsive frequencies when the phosphor is excited by the frequencies emitted by the diode.
Claims41
A white light emitting solid-state lamp comprising:
- a light emitting diode, an encapsulant, and a header;
- said diode comprising a conductive silicon carbide substrate for electrical contact and
- a Group III nitride active portion on said silicon carbide substrate for generating desired frequency photons under the application of current across said diode;
- said header comprising a reflective cup for supporting said diode and for providing electrical contact to said diode and to said active portion;
- said encapsulant including a phosphor, present in at least portions of said encapsulant for generating responsive frequencies when said phosphor is excited by the frequencies emitted by said diode;
- and
- an output of at least 75 lumens per watt at 20 milliamps drive current.
A white light emitting diode-based lamp comprising:
- a light emitting diode that emits in a portion of the spectrum selected from the ultraviolet, blue, and violet portions of the electromagnetic spectrum;
- a dimpled header supporting said diode, said dimple having a (functional) shape that maximizes the extraction of light from the diode in said dimple;
- a first portion of encapsulating resin covering said diode in said dimple and filling said dimple only to the extent necessary to cover said diode;
- a second portion formed of a mixture of said encapsulating resin with a phosphor and filling the remainder of said dimple to thereby separate said phosphor containing portion sufficiently from said diode to minimize said diode's absorption of light from the phosphor that can otherwise be extracted;
- and
- a lens on said filled dimple formed of said encapsulating resin for increasing and maximizing the extraction of light from the lamp.
A packaged light emitting diode lamp comprising:
- a conductive header;
- a light emitting diode on said header, said diode comprising a silicon carbide substrate, at least one active layer of indium gallium nitride, ohmic contacts in a vertical orientation with respect to said substrate and said active layer, and with the ohmic contact to the active layer being in electrical contact with said header;
- an encapsulant covering said diode and at least portions of said header;
- a phosphor in said encapsulant that emits visible light in response to the emission from said diode;
- and
- said packaged diode demonstrating at least 57 lumen per watt of white light at an operating current of 350 milliamps.
A packaged light emitting diode lamp comprising:
- a conductive header;
- a light emitting diode on said header, said diode comprising a silicon carbide substrate, at least one active layer of indium gallium nitride, ohmic contacts in a vertical orientation with respect to said substrate and said active layer, and with the ohmic contact to the active layer being in electrical contact with said header;
- an encapsulant covering said diode and at least portions of said header;
- a phosphor in said encapsulant that emits visible light in response to the emission from said diode;
- and
- said chip demonstrating at least 142 lumens per watt of white light at an operating current of 1 amp.
A method of forming a high efficiency white emitting semiconductor-based lamp, the method comprising:
- forming a cup-shaped dimple into a header base for providing electrical contact and a reflective background and structure;
- positioning a high frequency light emitting diode in the dimple and in electrical contact with said header;
- partially filling the dimple cup with an encapsulation material in an amount sufficient to cover the diode without filling the cup;
- curing the partially filled encapsulation material;
- filling the remainder of the dimple cup with a mixture of the encapsulation material and a phosphor responsive to the frequency produced by the diode to thereby separate the phosphor from direct contact with the diode to thereby minimize the diode's absorption of phosphorescent light;
- curing the remaining encapsulation material in the dimple cup;
- forming a solid lens of encapsulation material on the cured material in the dimple cup to enhance the extraction of light from the diode;
- and
- curing the lens material to form the finished lamp.
Dependencies are inferred from the claim text.