FOLDED 3-D LIGHT SHEETS CONTAINING PRINTED LEDS

• US 20150069431A1
• Filed: 09/09/2014
• Published: 03/12/2015
• Est. Priority Date: 09/09/2013
• Status: Active Grant

• Current Assignee: NthDegree Technologies Worldwide Inc.
• Original Assignee: NthDegree Technologies Worldwide Inc.
• Inventors: Oraw, Bradley Steven, Ray, Alexander, Thompson, Travis
• Granted Patent: US 9,324,693 B2
• Time in Patent Office: Days
• US Class Current: 257/89
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Abstract

A method of forming a light sheet includes printing a layer of inorganic LEDs on a first conductive surface of a substrate, depositing a first dielectric layer, and depositing a second conductor layer over the LEDs so that the LEDs are connected in parallel. At least one of the first conductive surface or the second conductor layer is transparent to allow light to escape. A phosphor layer may be formed over the light sheet so that the LED light mixed with the phosphor light creates white light. The flat light sheet is then folded, such as by molding, to form a three-dimensional structure with angled light emitting walls and reflective surfaces to control a directionality of the emitted light and improve the mixing of light. The folds may form rows of angled walls or polygons.

Claims

1. A light emitting device comprising:

a substrate having a first conductive surface;

a layer of inorganic light emitting diodes (LEDs) deposited on the first conductive surface so that a bottom electrode of the LEDs electrically contacts the first conductive surface;

a first dielectric layer deposited over the first conductive surface;

a second conductor layer over the LEDs so that a top electrode of the LEDs electrically contacts the second conductor layer, wherein at least one of the first conductive surface or the second conductor layer is transparent,

wherein the substrate, the first conductive surface, the layer of LEDs, the first dielectric layer, and the second conductor layer form a light sheet; and

wherein the light sheet is folded to form a folded light sheet having a plurality of light emitting walls at a plurality of angles.

2. The device of claim 1 wherein the first conductive surface and the substrate are transparent.

3. The device of claim 1 wherein the second conductor layer is transparent.

4. The device of claim 1 wherein the LEDs comprise blue light emitting LEDs, the device further comprising a phosphor layer over at least some of the LEDs.

5. The device of claim 1 wherein the light sheet is folded using a mold.

6. The device of claim 1 wherein the light sheet is folded to have linear rows of angled walls, wherein an area between opposing angled walls comprises a reflector.

7. The device of claim 1 wherein the light sheet comprises reflective areas and areas that generate light.

8. The device of claim 7 wherein the areas that generate light comprise areas that emit white light.

9. The device of claim 7 wherein the areas that generate light comprise areas that emit red, green, and blue light.

10. The device of claim 1 wherein folded light sheet forms an array of multi-walled polygons with a light exit opening and a reflective bottom surface.

11. The device of claim 10 wherein walls of the polygon include walls being at least partially reflective.

12. The device of claim 10 wherein walls of the polygon include opposing walls emitting a same color light, where different walls in the polygon emit different colors of light.

13. The device of claim 12 wherein all the LEDs are blue emitting LEDs, and at least some of the different walls include a layer of red-emitting phosphor and green-emitting phosphor.

14. The device of claim 10 wherein the polygons comprise boxes with four walls and a reflective bottom surface.

15. The device of claim 10 wherein the polygons comprise hexagons with six walls and a reflective bottom surface.

16. The device of claim 10 wherein the polygons comprise pyramids.

17. The device of claim 1 wherein the plurality of light emitting walls include walls that emit red, green, and blue light.

18. The device of claim 17 wherein the plurality of light emitting walls contain LEDs that emit red light, LEDs that emit green light, and LEDs that emit blue light.

19. The device of claim 1 further comprising a diffuser over the folded light sheet.

20. The device of claim 1 further comprising a material that structurally supports the folded light sheet.

21. The device of claim 1 wherein the layer of LEDs comprise microscopic printed LEDs.

22. A method of forming a light sheet comprising:

providing a substrate with a first conductive surface;

printing a layer of inorganic light emitting diodes (LEDs) on the first conductive surface so that a bottom electrode of the LEDs electrically contacts the first conductive surface;

depositing a first dielectric layer over the first conductive surface and along sidewalls of the LEDs;

depositing a second conductor layer over the LEDs so that a top electrode of the LEDs electrically contacts the second conductor layer, wherein at least one of the first conductive surface or the second conductor layer is transparent; and

wherein the substrate, the first conductive surface, the layer of LEDs, the first dielectric layer, and the second conductor layer form a light sheet; and

folding the light sheet to form a folded light sheet having a plurality of light emitting walls at a plurality of angles.

23. The method of claim 22 wherein the step of folding comprises molding the light sheet under heat and pressure.

24. The method of claim 22 wherein at least one of the first conductive surface, second conductor layer, and substrate are transparent.

25. The method of claim 22 wherein the light sheet is folded to have linear rows of angled walls, wherein an area between opposing angled walls comprises a reflector.

26. The method of claim 22 wherein the folded light sheet comprises reflective areas and areas that generate light.

27. The method of claim 26 wherein the areas that generate light comprise areas that emit white light.

28. The method of claim 26 wherein the areas that generate light comprise areas that emit red, green, and blue light.

29. The method of claim 22 wherein folded light sheet forms an array of multi-walled polygons with a light exit opening and a reflective bottom surface.

30. The method of claim 29 wherein walls of the polygon include walls being at least partially reflective.

31. The method of claim 29 wherein the polygons comprise at least four walls and a reflective bottom surface.

32. The method of claim 29 wherein the polygons comprise pyramids.

33. The method of claim 22 wherein the LEDs comprise blue light emitting LEDs, the device further comprising a phosphor layer over at least some of the LEDs.

34. The method of claim 22 wherein the plurality of light emitting walls contain LEDs that emit red light, LEDs that emit green light, and LEDs that emit blue light.