Integrated back light unit
View Patent ↗A light emitting device includes a support having an interstice and at least one LED located in the interstice and at least one of a waveguide or an optical launch having a transparent material encapsulating the at least one LED located in the interstice.
1. A method of making an integrated back light unit, comprising:
providing a light emitting diode (LED) assembly comprising a support having a top surface and a plurality of LEDs disposed on the top surface of the support, wherein the plurality of LEDs includes multiple rows of LEDs;
encapsulating the plurality of LEDs disposed on the support with transparent material which forms an optical launch, wherein the plurality of LEDs in the multiple rows are gang molded by a single continuous layer of the transparent material that encapsulates each of the plurality of LEDs in the LED assembly;
separating the assembly into multiple rows of encapsulated LEDs after the step of encapsulating the plurality of LEDs, by dicing through the single continuous layer of the transparent material and through the support to provide diced structures, wherein each of the diced structures comprises a separated row of encapsulated LEDs located on a diced portion of the support and encapsulated by a diced portion of the transparent material;
providing a light guiding plate having a light-receiving end surface and a major surface that is perpendicular to the light-receiving end surface and configured to emit light through the major surface upon receiving light through the light-receiving end surface; and
forming the integrated back light unit by optically coupling the light guiding plate to a first one of the diced structures containing the separated row of the encapsulated LEDs by taping the light-receiving end surface of the light guiding plate to the first one of the diced structures, such that the light-receiving end surface of the light guiding plate is parallel to the top surface of the diced portion of the support within the one of the diced structures.
2. The method of claim 1 , further comprising testing the plurality of LEDs prior to the step of separating.
3. The method of claim 2 , wherein the step of testing comprises testing each row of LEDs at one time.
4. The method of claim 1 , wherein greater than 90% of a surface of the support comprises LEDs.
5. The method of claim 4 , wherein 91-99% of the surface of the support comprises LEDs.
6. The method of claim 1 , wherein providing a light emitting diode (LED) assembly comprises flip chip bonding back emitting LEDs to the support and wire bonding front emitting LEDs to the support.
7. The method of claim 1 , wherein the plurality of LEDs comprises a plurality of different color LEDs.
8. The method of claim 1 , wherein the support comprises a lead frame.
9. The method of claim 1 , wherein the support comprises a molded lead frame.
10. The method of claim 9 , wherein providing a light emitting diode (LED) assembly comprises wire bonding LEDs to leads of the molded lead frame.
11. The method of claim 1 , further comprising electrically connecting at least a first row of the encapsulated LEDs to a circuit board.
12. The method of claim 11 , wherein the integrated back light unit comprises at least the first row of the encapsulated LEDs and the light guiding plate located on the circuit board.
13. The method of claim 1 , wherein the support comprises a printed circuit board.
14. The method of claim 1 , further comprising optically coupling each of the separated rows of encapsulated LEDs to a respective light guiding plate after dicing to provide the plurality of integrated back light units.
15. The method of claim 1 , wherein:
optically coupling the light guiding plate to the first one of the diced structures containing the separated row of the encapsulated LEDs by taping comprises taping the light-receiving end surface of the light guiding plate to the diced portion of the transparent material of the first one of the diced structures using a tape.
16. The method of claim 15 , wherein:
the single continuous layer of the transparent material includes a planar top surface that is perpendicular to the normal direction; and
the top surface of the support defines a normal direction that is perpendicular to the top surface of the support.
17. The method of claim 16 , wherein:
the diced portion of the support includes a top surface that is a portion of the top surface of the support prior to dicing;
the diced portion of the transparent material includes a transparent top surface that is a remaining portion of the planar top surface of the single continuous layer of the transparent material and that is parallel to the top surface of the diced portion of the support; and
each LED in the separated row of encapsulated LED is configured to provide light emission through the transparent top surface along a direction that is perpendicular to the top surface of the diced portion of the support.
18. The method of claim 17 , wherein coupling the light guiding plate to a row of the encapsulated LEDs within one of the diced structures by taping comprises taping the light-receiving end surface of the light guiding plate to the transparent top surface of the diced portion of the transparent material within the one of the diced structures.
19. The method of claim 18 , wherein:
the major surface of the light guiding plate is perpendicular to the top surface of the diced portion of the transparent material within the one of the diced structures, and to the top surface of the diced portion of the support within the one of the diced structures; and
the light-receiving end surface of the light guiding plate is parallel to the top surface of the diced portion of the transparent material within the one of the diced structures.
20. The method of claim 19 , wherein major surfaces of the tape are parallel to the light-receiving end surface of the light guiding plate, and are parallel to the transparent top surface of the diced portion of the transparent material within the one of the diced structures, and the row of the encapsulated LEDs within one of the diced structures is configured to emit light through the tape along a direction that is perpendicular to the surfaces of the tape.
21. The method of claim 19 , further comprising attaching a base plate having a respective major surface to an assembly of the one of the diced structures and the light guiding plate, wherein the based plate is disposed on an opposite side of the major surface of the light emitting plate that is configured to emit light, and the major surface of the base plate is parallel to the major surface of the light guide plate.
22. The method of claim 21 , wherein the major surface of the base plate is perpendicular to the light-receiving end surface of the light guiding plate, to the top surface of the diced portion of the transparent material within the one of the diced structures, and to the top surface of the diced portion of the support within the one of the diced structures.
23. The method of claim 19 , wherein the diced portion of the transparent material within the one of the diced structures constitutes an optical launch that mates the light emitting guide.
24. The method of claim 23 , further comprising disposing a reflective material over side surfaces of the optical launch, wherein the side surfaces extend generally along a direction that is perpendicular to the light-receiving end surface of the light guiding plate, to the top surface of the diced portion of the transparent material within the one of the diced structures.