Thin LED flash for camera

Patent metadata

Field	Value
Publication number	US-10120266-B2
Application number	US-201415104220-A
Country	US
Kind code	B2
Filing date	Dec 22, 2014
Priority date	Jan 6, 2014
Publication date	Nov 6, 2018
Grant date	Nov 6, 2018

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 substrate comprising the top surface of the LED die so that the LED die has anode and cathode electrodes on a bottom surface, the substrate being thicker than the LED semiconductor layers, wherein light emitted from the side surfaces is at least 30% of all light emitted by the LED;
a phosphor layer covering the top surface and side surfaces;
a reflector surrounding the LED die, the reflector having curved surfaces surrounding the LED die, 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; and
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.

2. The device of claim 1 , wherein the device is a flash for a camera.

3. The device of claim 2 , wherein an aspect ratio of the beam is substantially the same as an aspect ratio of a field of view of the camera.

4. The device of claim 1 , wherein the support structure is a flexible circuit.

5. The device of claim 1 , wherein the reflector comprises a stamped metal reflector, where the opening has a knife edge facing the LED die.

6. The device of claim 1 , wherein the lens has a focal length and wherein a distance from a side of the LED die, taken normal to the side of the LED die, to the reflector plus a distance from the reflector to the lens is approximately the focal length.

7. The device of claim 1 , wherein light from the at least one side surface of the LED die is at least 40% of all light emitted by the LED die.

8. The device of claim 1 , wherein light from the at least one side surface of the LED die is at least 50% of all light emitted by the LED die.

9. The device of claim 1 , wherein the substrate is a growth substrate for the LED semiconductor layers.

10. The device of claim 1 , wherein the phosphor layer conformally coats the top surface and the at least one side surface and has substantially uniform thickness.

11. The device of claim 1 , wherein the phosphor layer comprises phosphor particles infused in a binder, wherein the phosphor layer covers a portion of a top surface of the support structure, and wherein a bottom surface of the reflector is affixed to the support structure by the binder acting as an adhesive.

12. The device of claim 1 , wherein a footprint of the reflector is substantially the same as a footprint of the support structure.

13. The device of claim 1 , wherein a total height of the device is less than 1 mm.

14. The device of claim 1 , wherein a total height of the device is less than 2 mm.

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

• H01L33/60

  Electricity · mapped topic

• H01L33/505

  Electricity · mapped topic

• H01L33/501

  Electricity · mapped topic