Uniform, efficient, and color tunable ring flash for camera using LEDs with light emission from multiple sides
A device includes a light-emitting device (LED) having at least two vertical light-emitting sides, and a ring-shaped light guide having a bottom side, a top side comprising a light-emitting surface, an inner sidewall, and an outer sidewall defining an indentation having at least two vertical in-coupling surfaces mated to the at least two vertical light-emitting sides of the LED.
1. A light guide module, comprising:
a light guide configured to guide light in a ring as guided light, the ring defining a plane,
the light guide including a light-emitting surface that is generally planar, substantially parallel to the plane, and configured to emit at least a portion of the guided light,
the light guide further including a first light-accepting surface that is generally planar and positioned generally orthogonal to the light-emitting surface,
the light guide further including a second light-accepting surface that is generally planar and positioned generally orthogonal to the light-emitting surface, the second light-accepting surface being adjacent to the first light-accepting surface and angled with respect to the first light-accepting surface; and
a light-emitting diode configured to illuminate the light guide,
the light-emitting diode having a first light-producing surface that is generally planar and positioned to face the first light-accepting surface of the light guide,
the light-emitting diode having a second light-producing surface that is generally planar and positioned to face the second light-accepting surface of the light guide.
2. The light guide module of claim 1 , further comprising a light guide bezel surrounding the light guide.
3. The light guide module of claim 1 , further comprising a printed circuit board electrically coupled to the light-emitting diode, wherein the light-emitting diode and the light guide are mounted on the printed circuit board.
4. The light guide module of claim 1 , wherein the light guide further includes an opposing surface positioned opposite the light-emitting surface, the opposing surface being textured, the texturing configured to enhance emission of the guided light through the light-emitting surface.
5. The light guide module of claim 1 , wherein the light guide further includes an opposing surface positioned opposite the light-emitting surface, the opposing surface comprising dots that are configured to enhance emission of the guided light through the light-emitting surface.
6. The light guide module of claim 1 , wherein the light guide is shaped to guide the light via total internal reflection.
7. The light guide module of claim 1 , further comprising a reflector film positioned on the light guide away from the light-emitting surface.
8. The light guide module of claim 1 , further comprising a diffuser film positioned on the light-emitting surface.
9. The light guide module of claim 1 , further comprising a pattern positioned on the light-emitting diode on a side of the light-emitting diode that faces the light-emitting surface of the light guide, the pattern configured to obscure the light-emitting diode.
10. The light guide module of claim 1 ,
wherein the light guide further includes a third light-accepting surface that is generally planar and positioned generally orthogonal to the light-emitting surface;
wherein the light guide further includes a fourth light-accepting surface that is generally planar and positioned generally orthogonal to the light-emitting surface, the fourth light-accepting surface being adjacent to the third light-accepting surface and angled with respect to the third light-accepting surface; and
further comprising a second light-emitting diode configured to illuminate the light guide,
the second light-emitting diode having a third light-producing surface that is generally planar and positioned to face the third light-accepting surface of the light guide,
the second light-emitting diode having a fourth light-producing surface that is generally planar and positioned to face the fourth light-accepting surface of the light guide.
11. The light guide module of claim 10 , wherein the light-emitting diode and the second light-emitting diode are configured to emit light in the visible part of the electromagnetic spectrum.
12. The light guide module of claim 11 , wherein the light-emitting diode and the second light-emitting diode are configured to emit light having different wavelengths, and further comprising a driver being configured to:
drive the first light-emitting diode and the second light-emitting diode at different settings to tune a white color point for a mixture of light produced by the first light-emitting diode and the second light-emitting diode.
13. The light guide module of claim 1 , further comprising a lens positioned such that the light guide surrounds the lens.
14. The light guide module of claim 1 , wherein:
the first light-producing surface of the light-emitting diode is positioned directly adjacent to the first light-accepting surface of the light guide, such that there are no intervening optical elements between the first light-producing surface of the light-emitting diode and the first light-accepting surface of the light guide; and
the second light-producing surface of the light-emitting diode is positioned directly adjacent to the second light-accepting surface of the light guide, such that there are no intervening optical elements between the second light-producing surface of the light-emitting diode and the second light-accepting surface of the light guide.
15. The light guide module of claim 1 , wherein:
the first light-producing surface of the light-emitting diode is generally parallel to the first light-accepting surface of the light guide; and
the second light-producing surface of the light-emitting diode is generally parallel to the second light-accepting surface of the light guide.
16. The light guide module of claim 1 , wherein the light guide has a cross-section that is generally rectangular, the cross-section being taken in a plane that passes through a center of the light guide and is substantially orthogonal to the light-emitting surface.
17. The light guide module of claim 16 , wherein:
the light-emitting diode is shaped as a rectangular cuboid;
the first light-producing surface of the light-emitting diode is substantially orthogonal to the second light-producing surface of the light-emitting diode; and
the first light-accepting surface of the light guide is substantially orthogonal to the second light-accepting surface of the light guide.
18. The light guide module of claim 1 , wherein:
the light guide further includes a third light-accepting surface that is generally planar and positioned generally orthogonal to the light-emitting surface, the third light-accepting surface being adjacent to the second light-accepting surface and angled with respect to the second light-accepting surface; and
the light-emitting diode has a third light-producing surface that is generally planar and positioned to face the third light-accepting surface of the light guide.
19. The light guide module of claim 18 , wherein:
the third light-producing surface of the light-emitting diode is positioned directly adjacent to the third light-accepting surface of the light guide, such that there are no intervening optical elements between the third light-producing surface of the light-emitting diode and the third light-accepting surface of the light guide; and
the third light-producing surface of the light-emitting diode is generally parallel to the third light-accepting surface of the light guide.
20. The light guide module of claim 1 , wherein the first light-accepting surface and the second light-accepting surface extend from an outer diameter of the light guide and extend only partially toward an inner diameter of the light guide.
21. A method for producing a light guide module, the method comprising:
forming a light guide,
the light guide configured to guide light in a ring as guided light,
the ring defining a plane,
the light guide including a light-emitting surface that is generally planar, substantially parallel to the plane, and configured to emit at least a portion of the guided light,
the light guide further including a first light-accepting surface that is generally planar and positioned generally orthogonal to the light-emitting surface,
the light guide further including a second light-accepting surface that is generally planar and positioned generally orthogonal to the light-emitting surface, the second light-accepting surface being adjacent to the first light-accepting surface and angled with respect to the first light-accepting surface.