Phosphor coating with self-adjusting distance from LED chip

• US 6,635,363 B1
• Filed: 08/21/2000
• Issued: 10/21/2003
• Est. Priority Date: 08/21/2000
• Status: Active Grant

• Current Assignee: Current Lighting Solutions, LLC (f/k/a GE Lighting Solutions, LLC) (American Industrial Partners)
• Original Assignee: General Electric Company
• Inventors: Jansma, Jon, Duclos, Steven Jude, Bortscheller, Jacob C., Wojnarowski, Robert J.
• Primary Examiner(s): YAMNITZKY, MARIE ROSE
• Application Number:
  US09/642,901
• Time in Patent Office: 1,156 Days
• Field of Search: 428/690, 428/917, 428/161, 313/512, 313/112, 257/95, 257/98, 257/99, 257/100
• US Class Current: 428/690
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/49107 on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 24/32 of an individual layer connector
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/508 having a non-uniform spatial arrangement or non-uniform concentration, e.g. patterned wavelength conversion layer, wavelength conversion layer with a concentration gradient of the wavelength conversion material
• CPC Class Codes: Y10S 428/917 Electroluminescent
• CPC Class Codes: Y10T 428/24521 with component conforming to contour of nonplanar surface

Abstract

A light source (10) includes a light emitting component (32), such as a UV/blue light emitting diode or laser diode. A layer (62, 162, 262, 362) of a phosphor material is spaced from the light emitting component by a layer (60, 160, 260, 360) of a material which is transmissive to the light emitted by the light emitting component. The phosphor material converts a portion of the light emitted by the light emitting component to light of a longer wavelength such as yellow light. In a preferred embodiment, the light transmissive layer valise in thickness over the light emitting component so that the phosphor is spaced further from the diode in regions where the emission is higher. This increases the Surface area of the phosphor in these regions and minimizes the effects of overheating and saturation on the phosphor emission.

Claims

1. A light source comprising:

a light emitting component which emits light when a voltage is applied, an intensity of the light varying across the light emitting component at the applied voltage;

a layer of a phosphor material positioned to receive light emitted by the light emitting component, the phosphor material converting at least a portion of the light to light of a different wavelength; and

a layer of a light transmissive material which spaces the phosphor material from the light emitting component, the thickness of the layer of light transmissive material varying across the layer of light transmissive material in proportion to the intensity of the light emitted by the light emitting component at the voltage, the thickness of the layer of light transmissive material being greater in regions where the light intensity is hither and smaller in regions where the light intensity is lower.

2. The light source of claim 1, wherein the light emitting component is selected from the group consisting of light emitting diodes and laser diodes.

3. The light source of claim 2, wherein the light emitting component emits light in at least one of the blue region and the UV region of the electromagnetic spectrum.

4. The light source of claim 3, wherein the phosphor includes a yellow-emitting phosphor.

6. The light source of claim 1, wherein the layer of light transmissive material is formed from a light-curable material.

7. The light source of claim 6, wherein light-curable material is curable by light emitted by the light emitting component.

8. The light source of claim 6, wherein the light emitting component emits light in at least one of the blue region and the UV region of the electromagnetic spectrum and the light-curable material is a blue or UV-curable material.

9. The light source of claim 8, wherein the blue or UV-curable material includes at least one of an epoxy and a polyvinyl alcohol.

10. The light source of claim 1, wherein the layer of light transmissive material includes at least an outer portion, adjacent the phosphor layer, formed from a material which is curable by exposure to at least one of UV and blue light.

5. A light source comprising:

a light emitting component which emits light, the light emitting component including;

a die; and

a die attach material, the die attach material being formed from a material which is curable by light emitted by the light emitting component;

a layer of a phosphor material positioned to receive light emitted by the light emitting component, the phosphor material converting at least a portion of the light to light of a different wavelength; and

a layer of a light transmissive material which spaces the phosphor material from the light emitting component, a thickness of the light transmissive material varying across the layer of light transmissive material in relation to the intensity of light emitted by the light emitting component under a fixed set of operating conditions the thickness of the layer of light transmissive material being greater in regions where the light intensity is higher and smaller in regions where the light intensity is lower.

11. A light source comprising:

a light emitting component which emits light of at least a first wavelength, an intensity of the light varying across the light emitting component when a given voltage is applied;

a layer of a phosphor-containing material positioned to receive light emitted by the light emitting component and convert the light of the first wavelength to light of a second wavelength; and

a layer of a light transmissive material which spaces the phosphor layer from the light emitting component, the layer of light transmissive material having a thickness which is proportionally greater in regions where the intensity of the light emitted by the light emitting component is higher than in regions where the intensity of the light emitted by the light emitting component is lower.

12. The light source of claim 11, wherein the light emitting component is selected from the group consisting of light emitting diodes and laser diodes.

13. The light source of claim 11, wherein the phosphor layer is formed from a material which includes:

a phosphor; and

a light-curable material which is curable by light emitted by the light emitting component.

14. The light source of claim 13, wherein the light emitting component emits light in at least one of the blue region and the UV region of the electromagnetic spectrum and the light-curable material is a blue or UV-curable material.

15. The light source of claim 11, wherein the phosphor includes a yellow-emitting phosphor.

16. The light source of claim 11, wherein the light emitting component includes:

a die; and

a die attach material, the die attach material being formed from a material which is curable by light emitted by the light emitting component.

17. A light source formed by a method comprising;

providing a layer of a curable material on a light emitting component;

curing at least a portion of the curable material with the light emitting component to form a layer of a light transmissive material; and

forming a layer of a phosphor material over the light transmissive material, the light transmissive material spacing the phosphor material from the light emitting component by a distance which varies across the layer of light transmissive material in proportion to the intensity of light emitted by the light emitting component during curing, the distance being greater in regions where the intensity of the light emitted by the light emitting component is higher than in regions where the intensity of the light emitted by the light emitting component is lower.