Light emitting device

Patent metadata

Field	Value
Publication number	US-9351371-B2
Application number	US-201113991987-A
Country	US
Kind code	B2
Filing date	Nov 8, 2011
Priority date	Dec 9, 2010
Publication date	May 24, 2016
Grant date	May 24, 2016

Abstract

Provided is a light emitting device in which with the general color rendering index Ra and the special color rendering index R9 maintained at high numeric values, the light emission efficiency is prevented from being reduced as much as possible, and the high color rendering and the high efficiency are achieved so as to be usable for general lighting usage. The device includes at least one light emitting element 6 emitting a light having a peak emission wavelength in a near-ultraviolet to blue region, and a phosphor layer 5 containing a green phosphor excited by a primary light emitted from the light emitting element 6 and emitting a light having a peak emission wavelength in a green region, a first red phosphor excited by the primary light and emitting a light having a peak emission wavelength in a red region, and a second red phosphor exited by the primary light and emitting a light having a peak emission wavelength different from that of the first red phosphor in the red region.

First claim

The invention claimed is:

1. A light emitting device comprising:
at least one light emitting element emitting a light comprising a peak emission wavelength in a near-ultraviolet to blue region; and
a phosphor layer comprising a green phosphor excited by a primary light emitted from the light emitting element and emitting a light comprising a peak emission wavelength in a green region, a first red phosphor excited by the primary light and emitting a light comprising a peak emission wavelength in a red region, and a second red phosphor exited by the primary light and emitting a light comprising a peak emission wavelength different from that of the first red phosphor in the red region, wherein
the peak emission wavelength of the green phosphor falls within a wavelength range of 510 nm or more and 550 nm or less, the green phosphor comprising a half-value width of 95 nm or more in emission spectrum,
the peak emission wavelength of the first red phosphor falls within a wavelength range of 610 nm or more and less than 625 nm, the first red phosphor comprising a half-value width of 85 to 110 nm in emission spectrum, and
the peak emission wavelength of the second red phosphor falls within a wavelength range of 625 nm or more and 670 nm or less, the second red phoshor comprising a half-value width of 85 to 110 nm in emission spectrum.

2. The light emitting device according to claim 1 , wherein
the light emitting element comprises an LED chip emitting a light comprising a peak emission wavelength within a wavelength range of 350 nm or more and 490 nm or less.

3. The light emitting device according to claim 1 , wherein
the light emitting element comprises an LED chip emitting a light comprising a peak emission wavelength within a wavelength range of 430 nm or more and 490 nm or less.

4. The light emitting device according to claim 1 , wherein
the light emitting element comprises an LED chip emitting a light comprising a peak emission wavelength within a wavelength range of 350 nm or more and less than 430 nm, and
the phosphor layer further comprises a blue phosphor excited by the primary light emitted from the light emitting element and emitting a light comprising a peak emission wavelength in a wavelength range of 430 nm or more and 490 nm or less.

5. The light emitting device according to claim 2 , wherein the light emitting element comprises an InGaN series LED chip.

6. The light emitting device according to claim 1 , wherein the green phosphor comprises any one of an A1 5 Lu x O y : Ce series phosphor, a Ca 3 (Sc, Mg) 2 Si 3 O 12 : Ce series phosphor, and an A1 5 O 12 Y 3 : Ce series phosphor.

7. The light emitting device according to claim 1 , wherein each of the first and second red phosphors comprises a (Sr, Ca)A1SiN 3 : Eu series phosphor, or a CaA1SiN 3 : Eu series phosphor.

8. The light emitting device according to claim 1 , wherein each weight allocation to total weight of the first and second red phosphors is adjusted so that a general color rendering index Ra shows that 80≦Ra≦97.

9. The light emitting device according to claim 8 , wherein a weight ratio of the second red phosphor to the total weight of the first and second red phosphors is adjusted to be 25% or less so that the general color rendering index Ra shows that 80≦Ra≦85.

10. The light emitting device according to claim 8 , wherein the weight ratio of the second red phosphor to the total weight of the first and second red phosphors is adjusted to be 25% or more and 75% or less so that the general color rendering index Ra shows that 85 ≦Ra≦90.

11. The light emitting device according to claim 8 , wherein the weight ratio of the second red phosphor to the total weight of the first and second red phosphors is adjusted to be 75% or more so that the general color rendering index Ra shows that 90 ≦Ra≦97.

12. The light emitting device according to claim 1 , wherein
the phosphor layer is formed such that grains of the green phosphor, grains of the first red phosphor, and grains of the second red phosphor are mixed in a transparent resin, and
the light emitting element is sealed with the phosphor layer, or a transparent resin layer provided to be closer to the light emitting element than the phosphor layer and not containing a phosphor.

13. The light emitting device according to claim 1 , wherein
the phosphor layer is formed to have a laminated structure composed of a green phosphor layer comprising grains of the green phosphor mixed in a transparent resin, a first red phosphor layer comprising grains of the first red phosphor mixed in a transparent resin, and a second red phosphor layer comprising grains of the second red phosphor mixed in a transparent resin, and
the light emitting element is sealed with a lowermost layer of the phosphor layer, or a transparent resin layer provided to be closer to the light emitting element than the phosphor layer and not containing a phosphor.

14. The light emitting device according to claim 1 , wherein
the phosphor layer is formed to have a laminated structure composed of a green phosphor layer comprising grains of the green phosphor mixed in a transparent resin, and a red phosphor layer comprising grains of the first red phosphor and grains of the second red phosphor mixed in a transparent resin, and
the light emitting element is sealed with a lowermost layer of the phosphor layer, or a transparent resin layer provided to be closer to the light emitting element than the phosphor layer and not containing a phosphor.

15. The light emitting device according to claim 13 , wherein the green phosphor layer is positioned above a layer in which the first red phosphor and the second red phosphor exist.

16. The light emitting device according to claim 12 , wherein a median value of a grain diameter of the green phosphor is 8 μm or more and 20 μm or less.

17. The light emitting device according to claim 12 , wherein a median value of a grain diameter of each of the first red phosphor and the second red phosphor is 5 μm or more and 15 μm or less.

18. The light emitting device according to claim 12 , wherein the transparent resin of each layer of the phosphor layer is a silicone resin having a viscosity of 3 Pa·s or more and 20 Pa·s or less before being hardened.

Assignees

• Ishizaki Shinya
• Sharp Kk

Inventors

• Ishizaki Shinya

Classifications

• H10W90/753

  between laterally-adjacent chips · CPC title

• H10W90/00

  Package configurations · CPC title

• C09K11/77348

  Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides · CPC title

• H10H20/8515

  not being in contact with the bodies · CPC title

• H10H20/8514

  characterised by their shape, e.g. plate or foil · CPC title