Folded 3-D light sheets containing printed LEDs
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.
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 an array of repeated identical light emitting segments, each segment having a plurality of planar light emitting walls at a plurality of angles such that some of the light emitting walls face each other for mixing of light.
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. 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;
wherein the light sheet is folded to form a folded light sheet having a plurality of light emitting walls at a plurality of angles; and
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 the folded light sheet forms an array of multi-walled polygons with a light exit opening and a reflective bottom surface.
11. 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;
wherein the light sheet is folded to form a folded light sheet having a plurality of light emitting walls at a plurality of angles;
wherein the folded light sheet forms an array of multi-walled polygons with a light exit opening and a reflective bottom surface; and
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 first walls emitting a same first color light, wherein one or more second walls in the polygon emit a second color light different from the first color light.
13. The device of claim 12 wherein all the LEDs are blue emitting LEDs, and at least some of the first walls or second 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.