Backlight Including Side-Emitting Semiconductor Light Emitting Devices

• US 20090045420A1
• Filed: 08/16/2007
• Published: 02/19/2009
• Est. Priority Date: 08/16/2007
• Status: Active Grant

• Current Assignee: Philips Lumileds Lighting Company LLC (Apollo Global Management, Inc.), Nippon Leiz Co, Ltd.
• Original Assignee: Philips Lumileds Lighting Company LLC (Apollo Global Management, Inc.)
• Inventors: Harbers, Gerard, Bierhuizen, Serge, Eng, Gregory W.
• Granted Patent: US 7,538,359 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: G02B 6/0021 for housing at least a part of the light source, e.g. by forming holes or recesses
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: G02B 6/0083 Details of electrical connections of light sources to drivers, circuit boards, or the like
• CPC Class Codes: H01L 2224/05568 the whole external layer protruding from the surface
• CPC Class Codes: H01L 2224/05573 Single external layer
• CPC Class Codes: H01L 2224/05624 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/05639 Silver [Ag] as principal constituent
• CPC Class Codes: H01L 2224/0603 Bonding areas having different sizes, e.g. different heights or widths
• CPC Class Codes: H01L 2224/13 of an individual bump connector
• 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 33/58 Optical field-shaping elements

Abstract

Individual side-emitting LEDs are separately positioned in a waveguide, or mounted together on a flexible mount then positioned together in a waveguide. As a result, the gap between each LED and the waveguide can be small, which may improve coupling of light from the LED into the waveguide. Since the LEDs are separately connected to the waveguide, or mounted on a flexible mount, stress to individual LEDs resulting from changes in the shape of the waveguide is reduced.

Claims

1. A structure comprising:

a semiconductor light emitting device comprising;

a semiconductor structure comprising a light emitting layer disposed between an n-type region and a p-type region;

a first contact electrically connected to the n-type region;

a second contact electrically connected to the p-type region, wherein the first and second contacts are formed on a first side of the semiconductor structure such that the semiconductor structure is a flip chip;

a reflector disposed over a second side of the semiconductor structure, substantially parallel to the major surface of the light emitting layer, such that a majority of light exiting the light emitting device exits through side surfaces of the light emitting device;

a first transparent member with at least one opening in which at least a portion of the light emitting device is positioned, whereby at least a portion of light exiting the sides of the light emitting device is optically coupled into the first transparent member; and

a second transparent member with at least one opening in which at least a portion of the first transparent member is positioned.

2. The structure of claim 1 wherein the semiconductor light emitting device further comprises a wavelength-converting material disposed between the reflector and the semiconductor structure, where in the wavelength-converting material is configured to absorb light of a wavelength emitted by the light emitting layer and emit light of a longer wavelength.

3. The structure of claim 1 wherein the opening in the first transparent member does not extend through an entire thickness of the first transparent member.

4. The structure of claim 1 further comprising an alignment feature disposed on an edge of the first transparent member and a complimentary alignment feature disposed on an edge of the opening in the second transparent member.

5. The structure of claim 1 further comprising an adhesive disposed between the first transparent member and the second transparent member.

6. The structure of claim 1 wherein the opening in the second transparent member is a slot on an edge of the second transparent member.

7. The structure of claim 1 wherein an edge of the first transparent member is curved.

8. The structure of claim 1 wherein the semiconductor light emitting device is attached to a mount.

9. The structure of claim 8 wherein the mount is positioned adjacent the first transparent member.

10. The structure of claim 8 wherein the mount is positioned in a groove formed in the first transparent member.

11. The structure of claim 10 wherein the mount is connected to the first transparent member by a press fit between the mount and the groove.

12. The structure of claim 8 wherein the mount is reflective.

13. The structure of claim 1 wherein the opening in the first transparent member has sidewalls, at least one sidewall having varying angles along a length of the sidewall to vary a refraction of light along the sidewall.

14. A structure comprising:

a semiconductor light emitting device comprising;

a semiconductor structure comprising a light emitting layer disposed between an n-type region and a p-type region;

a first contact electrically connected to the n-type region;

a second contact electrically connected to the p-type region, wherein the first and second contacts are formed on a first side of the semiconductor structure such that the semiconductor structure is a flip chip;

a reflector disposed over a second side of the semiconductor structure, substantially parallel to the major surface of the light emitting layer, such that a majority of light exiting the light emitting device exits through side surfaces of the light emitting device;

a mount, wherein the semiconductor light emitting device is attached to the mount;

a transparent member comprising;

an opening in which at least a portion of the light emitting device is positioned; and

a groove in which at least a portion of the mount is positioned;

wherein at least a portion of light exiting the sides of the light emitting device is optically coupled into the transparent member; and

wherein the mount is connected to the transparent member by a press fit between the mount and the groove.

15. The structure of claim 14 wherein the opening in the transparent member has sidewalls, at least one sidewall having varying angles along a length of the sidewall to vary a refraction of light along the sidewall.

16. The structure of claim 14 wherein a depth of the opening is greater than a depth of the groove.

17. The structure of claim 14 further comprising a gap between an edge of the opening and a side of the light emitting device.

20. The structure of claim 14 wherein the semiconductor light emitting device is a first semiconductor light emitting device, the structure further comprising:

at least one additional semiconductor light emitting device;

the transparent member having at least one additional opening in which at least a portion of the at least one additional semiconductor light emitting device is positioned; and

a flexible circuit board to which the first semiconductor light emitting device and the at least one additional semiconductor light emitting device are physically and electrically connected.

18. A method comprising:

providing a semiconductor light emitting device comprising;

a semiconductor structure comprising a light emitting layer disposed between an n-type region and a p-type region;

a first contact electrically connected to the n-type region;

a second contact electrically connected to the p-type region, wherein the first and second contacts are formed on a first side of the semiconductor structure such that the semiconductor structure is a flip chip;

a reflector disposed over a second side of the semiconductor structure, substantially parallel to the major surface of the light emitting layer, such that a majority of light exiting the light emitting device exits through side surfaces of the light emitting device;

positioning at least a portion of the light emitting device in an opening in a first transparent member, whereby at least a portion of light exiting the sides of the light emitting device is optically coupled into the first transparent member; and

positioning at least a portion of the first transparent member in an opening in a second transparent member.

19. The method of claim 18 wherein positioning at least a portion of the first transparent member in an opening in the second transparent member comprises aligning an alignment feature disposed on an edge of the first transparent member with a complimentary alignment feature disposed on an edge of a slot formed in an edge of the second transparent member.