White light emitting device

Abstract

A white light emitting device includes a structure for emitting white light having at least four wavelengths by using two or less LEDs, where the LEDs include a blue/green LED emitting blue and green wavelengths of light. The device also includes means for emitting red wavelength of light.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a graph showing a light emission spectrum of a conventional white light emitting device according to the prior art;

FIG. 2 is a graph showing light emission spectrums of another type of conventional light emitting devices according to the prior art;

FIG. 3 is a schematic sectional view illustrating a white light emitting device according to an embodiment of the present invention;

FIG. 4 is a graph showing a light emission spectrum of the white light emitting device shown in FIG. 3;

FIG. 5 is a graph showing external quantum efficiency of an InGaN-based LED and an InGaAlP-based LED with respect to wavelength;

FIG. 6 is a schematic sectional view illustrating a white light emitting device according to another embodiment of the present invention;

FIG. 7 is a schematic sectional view illustrating a white light emitting device according to further another embodiment of the present invention;

FIG. 8 is a graph showing a light emission spectrum of the white light emitting device shown in FIG. 7;

FIG. 9 is a schematic sectional view illustrating a white light emitting device according to still another embodiment of the present invention;

FIG. 10 is a graph showing a light emission spectrum of the white light emitting device shown in FIG. 9;

FIG. 11 is a schematic sectional view illustrating a white light emitting device according to yet another embodiment of the present invention; and

FIG. 12 is a graph showing a light emission spectrum of the white light emitting device shown in FIG. 11.

Claims

1. A white light emitting device comprising: a structure for emitting white light having at least four wavelengths by using two or less light emitting diodes (LEDs), wherein the LEDs comprise a blue/green LED emitting blue and green wavelengths of light; andthe device comprising red light emitting means.

2. The white light emitting device according to claim 1, wherein the blue/green LED comprises an InGaN-based LED.

3. The white light emitting device according to claim 1, wherein the red light emitting means comprises an InGaAlP-based LED.

4. The white light emitting device according to claim 1, wherein the red light emitting means comprises red phosphor.

5. The white light emitting device according to claim 1, wherein the red light emitting means comprises a red Photon Recycling System (PRS).

6. The white light emitting device according to claim 1, the white light has a light emission spectrum with a blue peak wavelength in the range of 440 to 470 nm, and a green peak wavelength in the range of 500 to 530 nm, a yellow peak wavelength in the range of 560 to 580 nm and a red peak wavelength in the range of 620 to 640 nm.

7. The white light emitting device according to claim 1, the white light has a light emission spectrum with a blue peak wavelength in the range of 450 to 460 nm, a green peak wavelength in the range of 505 to 515 nm, and a yellow peak wavelength in the range of 565 to 575 nm, and a red peak wavelength in the range of 630 to 640 nm.

8. The white light emitting device according to claim 7, the white light has a color rendering index of at least 95.

9. The white light emitting device according to claim 1, further comprising yellow phosphor, wherein the red light emitting means comprises at least one selected from a group consisting of a red LED, a red PRS and red phosphor.

10. The white light emitting device according to claim 9, wherein the yellow phosphor has a peak wavelength in the range of 540 to 590 nm.

11. The white light emitting device according to claim 1, wherein the red light emitting means comprises an amber/red LED emitting amber and red wavelengths of light.

12. The white light emitting device according to claim 1, wherein the blue/green LED is adapted to emit amber wavelength of light along with blue and green wavelengths of light, and the red light emitting means comprises a red LED emitting red wavelength of light.