Thin LED flash for camera

Patent metadata

Field	Value
Publication number	US-10324359-B2
Application number	US-201816176184-A
Country	US
Kind code	B2
Filing date	Oct 31, 2018
Priority date	Jan 6, 2014
Publication date	Jun 18, 2019
Grant date	Jun 18, 2019

Abstract

A thin flash module for a camera uses a flexible circuit as a support surface. A blue GaN-based flip chip LED die is mounted on the flex circuit. The LED die has a thick transparent substrate forming a “top” exit window so at least 40% of the light emitted from the die is side light. A phosphor layer conformally coats the die and a top surface of the flex circuit. A stamped reflector having a knife edge rectangular opening surrounds the die. Curved surfaces extending from the opening reflect the light from the side surfaces to form a generally rectangular beam. A generally rectangular lens is affixed to the top of the reflector. The lens has a generally rectangular convex surface extending toward the die, wherein a beam of light emitted from the lens has a generally rectangular shape corresponding to an aspect ratio of the camera's field of view.

First claim

What is claimed is:

1. A light emitting device comprising:
a support structure;
a light emitting diode (LED) die mounted on the support structure,
the LED die having a top surface and at least one side surface and comprising LED semiconductor layers and a transparent substrate, the LED semiconductor layers having a thickness and the transparent substrate having a thickness, the substrate comprising the top surface of the LED die, a ratio of substrate thickness to the LED semiconductor layers thickness being 2 or greater and the ratio of the area of the side surface to the area of the top surface being 1 or greater;
a phosphor layer covering the top surface and side surfaces;
a reflector surrounding the LED die, the reflector having curved surfaces surrounding the LED, wherein the curved surfaces extend from a generally rectangular opening for the LED die and reflect the light from the side surfaces of the LED die to form a generally rectangular beam;
a generally rectangular lens affixed to walls of the reflector, the lens having a generally rectangular convex surface extending toward the LED die and a flat top surface facing away from the LED die; and
a thickness from a bottom surface of the support structure to the flat top surface of the lens being 2 mm or less.

2. The device of claim 1 , wherein the shortest distance from the top surface of the LED die and the convex surface of the lens is 0.3 mm or less.

3. The device of claim 1 , wherein the convex surface of the lens improves the uniformity of the generally rectangular beam.

4. The device of claim 1 , wherein the thickness from the bottom surface of the support structure to the flat top surface of the lens is 1 mm or less.

5. The device of claim 1 , wherein the ratio of substrate thickness to the LED semiconductor layers thickness is 10 or greater.

6. The device of claim 1 , wherein the ratio of substrate thickness to the LED semiconductor layers thickness is 50 or greater.

7. The device of claim 1 , wherein the ratio of the area of the side surface to the area of the top surface is 2 or greater.

8. The device of claim 1 , wherein an aspect ratio of the beam is 4:3.

9. The device of claim 1 , wherein the support structure is flexible.

10. The device of claim 1 , wherein a thickness of the support structure is 0.05 mm or less.

11. The device of claim 1 , wherein the transparent substrate is glass.

12. The device of claim 1 , wherein the transparent substrate has a roughened surface opposite the LED die.

13. The device of claim 1 , wherein the transparent substrate has a roughened surface proximate to the top surface of the LED die.

14. The device of claim 1 , further comprising a dielectric layer between at least a portion of the support structure and the reflector.

15. The device of claim 14 , wherein the dielectric layer is an adhesive.

16. The device of claim 1 , wherein the reflector is stamped.

17. The device of claim 1 , wherein the reflector is aluminum.

18. The device of claim 1 , wherein the curved surfaces of the reflector are silver.

19. The device of claim 1 , wherein the LED die is one of a flip chip, lateral chip, and vertical chip.

20. The device of claim 1 , wherein the generally rectangular opening of the reflector and the generally rectangular lens are generally square.

Assignees

• Lumileds Llc

Inventors

• Butterworth Mark Melvin

Classifications

• G03B2215/0567

  Solid-state light source, e.g. LED, laser · CPC title

• G03B15/05 Primary

  Combinations of cameras with electronic flash apparatus; Electronic flash units · CPC title

• H01L33/58

  Electricity · mapped topic

• H01L33/501

  Electricity · mapped topic

• H01L33/505

  Electricity · mapped topic