Light-emitting apparatus including photoluminescent layer

• US 9,899,577 B2
• Filed: 06/01/2016
• Issued: 02/20/2018
• Est. Priority Date: 06/08/2015
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Inventors: Hashiya, Akira, Hirasawa, Taku, Inada, Yasuhisa, Matsuo, Mikiko
• Primary Examiner(s): Naraghi, Ali
• Application Number:
  US15/169,771
• Publication Number:
  US 20160359091A1
• Time in Patent Office: 629 Days
• Field of Search: None
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/508 having a non-uniform spatial arrangement or non-uniform concentration, e.g. patterned wavelength conversion layer, wavelength conversion layer with a concentration gradient of the wavelength conversion material

Abstract

A light-emitting apparatus comprising a photoluminescent layer that emits light in response to excitation light and has a light-emitting surface, the light from the photoluminescent layer being emitted through the light-emitting surface. The light-emitting surface includes a first region and a second region. The light from the photoluminescent layer includes first light having a wavelength λ_a in air. The first light emitted through the first region has a smaller directional angle than the first light emitted through the second region.

Claims

1. A light-emitting apparatus comprising a photoluminescent layer that emits light in response to excitation light and has a light-emitting surface, the light from the photoluminescent layer being emitted through the light-emitting surface,

wherein the light-emitting surface includes a first region and a second region,

the light from the photoluminescent layer includes first light having a wavelength λ

_a in air,

the first light emitted through the first region has a smaller directional angle than the first light emitted through the second region,

the photoluminescent layer has a periodic structure in the first region, the periodic structure having projections or recesses or both, and

a refractive index n_wav-a of the photoluminescent layer for the first light and a period p_a of the periodic structure satisfy λ

_a/n_wav-a<

p_a<

λ

_a.

2. The light-emitting apparatus according to claim 1, wherein

the photoluminescent layer has a periodic structure having projections or recesses or both in a region opposite the first region on another surface opposite the light-emitting surface, and

a refractive index n_wav-a of the photoluminescent layer for the first light and a period p_a of the periodic structure satisfy λ

_a/n_wav-a<

p_a<

λ

_a.

3. The light-emitting apparatus according to claim 1, wherein at least part of the second region is disposed at an end of the light-emitting surface.

4. The light-emitting apparatus according to claim 1, wherein the second region surrounds the first region.

5. The light-emitting apparatus according to claim 1, wherein the first region has a larger area than the second region.

6. The light-emitting apparatus according to claim 1, wherein the second region has a larger area than the first region.

7. The light-emitting apparatus according to claim 1, further comprising an excitation light source that emits the excitation light.

8. The light-emitting device according to claim 1, wherein the photoluminescent layer includes a phosphor.

9. The light-emitting device according to claim 1, wherein 380 nm≦

λ

_a≦

780 nm is satisfied.

10. The light-emitting device according to claim 1, further comprising a substrate that has refractive index n_s-a for the first light and is located on the photoluminescent layer, wherein λ

_a/n_wav-a<

p_a<

λ

_a/n_s-a is satisfied.

14. The light-emitting device according to claim 1, wherein the thickness of the photoluminescent layer, the refractive index n_wav-a and the period p_a are set to allow an electric field to be formed in the photoluminescent layer, in which antinodes of the electric field are located in or directly below the projections or recesses or both.

11. A light-emitting apparatus comprising:

a photoluminescent layer that emits light in response to excitation light; and

a light transmissive layer that is located on the photoluminescent layer, wherein

at least one of the photoluminescent layer and the light transmissive layer has a light-emitting surface, the light from the photoluminescent layer being emitted through the light-emitting surface, wherein

the light-emitting surface includes a first region and a second region,

the light from the photoluminescent layer includes first light having a wavelength λ

_a in air,

the first light emitted through the first region has a smaller directional angle than the first light emitted through the second region,

the light-emitting surface is a surface of the light-transmissive layer,

the light-transmissive layer has a periodic structure in the first region, the periodic structure having projections or recesses or both, and

a refractive index n_wav-a of the photoluminescent layer for the first light and a period p_a of the periodic structure satisfy λ

_aλ

n_wav-a<

p_a<

λ

_a.

12. The light-emitting apparatus according to claim 11, wherein the photoluminescent layer is in direct contact with the light-transmissive layer.

13. The light-emitting device according to claim 11, wherein the thickness of the photoluminescent layer, the refractive index n_wav-a and the period p_a are set to allow an electric field to be formed in the photoluminescent layer, in which antinodes of the electric field are located in or directly below the projections or recesses or both.