LED WITH MOLDED BI-DIRECTIONAL OPTICS

• US 20100109034A1
• Filed: 11/05/2008
• Published: 05/06/2010
• Est. Priority Date: 11/05/2008
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Philips Lumileds Lighting Company LLC (Apollo Global Management, Inc.), Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Bierhuizen, Serge, Butterworth, Mark
• Granted Patent: US 7,994,529 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: B29C 45/14655 connected to or mounted on a carrier, e.g. lead frame
• CPC Class Codes: B29C 45/1671 with an insert
• CPC Class Codes: B29D 11/00355 with a refractive index gradient
• CPC Class Codes: B29L 2031/3406 Components, e.g. resistors
• CPC Class Codes: G02B 6/003 Lens or lenticular sheet or layer
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: H01L 33/54 having a particular shape
• CPC Class Codes: H01L 33/58 Optical field-shaping elements

Abstract

A double-molded lens for an LED includes an outer lens molded around the periphery of an LED die and a collimating inner lens molded over the top surface of the LED die and partially defined by a central opening in the outer lens. The outer lens is formed using silicone having a relatively low index of refraction such as n=1.33-1.47, and the inner lens is formed of a higher index silicone, such as n=1.54-1.76, to cause TIR within the inner lens. Light not internally reflected by the inner lens is transmitted into the outer lens. The shape of the outer lens determines the side emission pattern of the light. The front and side emission patterns separately created by the two lenses may be tailored for a particular backlight or automotive application.

Claims

1. A method of forming a lighting apparatus comprising:

providing a light emitting diode (LED) die mounted on a submount, the LED die having a top surface;

molding an outer lens at least surrounding a periphery of the LED die using a first silicone having a first index of refraction, the outer lens having an opening over the top surface of the LED die; and

after molding the outer lens, molding an inner lens over the top surface of the LED die within the opening of the outer lens using a second silicone having a second index of refraction higher than the first index of refraction,

a shape of the inner lens acting to collimate light emitted by the top surface by total internal reflection (TIR),

a shape of the outer lens affecting a side emission pattern of light not internally reflected within the inner lens.

2. The method of claim 1 wherein the first index of refraction is at least about 1.3 and the second index of refraction is at least about 1.6.

3. The method of claim 1 wherein molding the outer lens comprises molding the outer lens to create a peak emission within 45°

-65°

from perpendicular to the top surface.

4. The method of claim 1 wherein molding the inner lens comprises molding the inner lens to create a light spreading pattern between 10°

-35°

from perpendicular to the top surface.

5. The method of claim 1 wherein molding the outer lens comprises molding the outer lens to have an approximately semi-hemispherical outer sidewall surface.

6. The method of claim 1 wherein molding the inner lens comprises molding the inner lens so that a top of the inner lens is flat.

7. The method of claim 1 wherein molding the inner lens comprises molding the inner lens so that a top of the inner lens has a light spreading feature.

8. The method of claim 1 wherein molding the inner lens and molding the outer lens comprise molding the inner lens and outer lens to be symmetrical about a center axis.

9. The method of claim 1 wherein molding the inner lens comprises molding the inner lens to be substantially cylindrical.

10. The method of claim 1 wherein molding the inner lens comprises molding the inner lens to be approximately parabolic.

11. The method of claim 1 wherein molding the outer lens comprises molding the first silicone to form a layer of the first silicone over the top surface of the LED die, wherein the layer has a non-flat shape to achieve a desired emission pattern.

12. The method of claim 11 wherein the layer includes light scattering features.

13. A lighting apparatus comprising:

a light emitting diode (LED) die mounted on a submount, the LED die having a top surface;

a molded outer lens at least surrounding a periphery of the LED die, the outer lens comprising a first silicone having a first index of refraction, the outer lens having an opening over the top surface of the LED die; and

a molded inner lens over the top surface of the LED die within the opening of the outer lens, the inner lens comprising a second silicone having a second index of refraction higher than the first index of refraction,

a shape of the inner lens acting to collimate light emitted by the top surface by total internal reflection (TIR),

a shape of the outer lens affecting a side emission pattern of light not internally reflected within the inner lens.

14. The apparatus of claim 13 wherein a plurality of LEDs having the inner lens and outer lens are optically coupled to an edge of a backlight waveguide.

15. The apparatus of claim 13 wherein the outer lens creates a peak emission within 45°

-65°

from perpendicular to the top surface, and the inner lens creates a light spreading pattern between 10°

-35°

from perpendicular to the top surface.