Light emitting device
Disclosed herein is a light emitting device. The light emitting device includes a light emitting diode disposed on a substrate to emit light of a first wavelength. A transparent molding part encloses the LED, a lower wavelength conversion material layer is disposed on the transparent molding part, and an upper wavelength conversion material layer is disposed on the lower wavelength conversion material layer. The lower wavelength conversion material layer contains a phosphor converting the light of the first wavelength into light of a second wavelength longer than the first wavelength, and the upper wavelength conversion material layer contains a phosphor converting the light of the first wavelength into light of a third wavelength, which is longer than the first wavelength but shorter than the second wavelength. Light produced via wavelength conversion is prevented from being lost by the phosphor. Light emitting devices including a multilayer reflection mirror are also disclosed.
1. A light emitting device, comprising:
a first light emitting diode disposed on a substrate, the first light emitting diode to emit light of a first wavelength;
a wavelength conversion material enclosing the first light emitting diode and containing a phosphor for performing wavelength conversion of a portion of the light of the first wavelength emitted from the first light emitting diode;
a second light emitting diode separated from the first light emitting diode and disposed on the substrate, the second light emitting diode to emit light of a second wavelength longer than the first wavelength; and
a dielectric multilayer reflection mirror formed on the wavelength conversion material and including at least one pair of dielectric layers,
wherein the layers of the at least one pair of dielectric layers do not have the same refractive index,
wherein the at least one pair of dielectric layers reflect the light of the second wavelength incident on the wavelength conversion material, and
wherein the dielectric multilayer reflection mirror is disposed on a portion only of an upper surface of the wavelength conversion material.
2. The light emitting device according to claim 1 , wherein each of the dielectric layers has a thickness “d” satisfying the relationship: d=(2m−1)λ/4n (where n indicates a refractive index of each of the dielectric layers, λ indicates the second wavelength, and m indicates an integer greater than or equal to 1).
3. The light emitting device according to claim 1 , further comprising:
a sealing resin enclosing the wavelength conversion material and the second light emitting diode, the sealing resin having a lower refractive index than the dielectric layer having the higher refractive index.
4. The light emitting device according to claim 1 , further comprising:
another second light emitting diode symmetrically disposed to the second light emitting diode centered on the first light emitting diode.
5. The light emitting device according to claim 1 , wherein the wavelength conversion material is a material layer formed on the light emitting diode and having a uniform thickness.
6. The light emitting device according to claim 1 , wherein the first light emitting diode emits blue light or ultraviolet rays having a peak wavelength of 490 nm or less; and
wherein the second light emitting diode emits red light having a peak wavelength of 580 nm or more.