Light-emitting device including photoluminescent layer

• US 10,113,712 B2
• Filed: 03/03/2016
• Issued: 10/30/2018
• Est. Priority Date: 03/13/2015
• 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: Inada, Yasuhisa
• Primary Examiner(s): Porta, David
• Assistant Examiner(s): Faye, Mamadou
• Application Number:
  US15/060,583
• Publication Number:
  US 20160265749A1
• Time in Patent Office: 971 Days
• CPC Class Codes: F21V 13/14 the elements being filters or photoluminescent elements, reflectors and refractors
• CPC Class Codes: F21V 14/02 by movement of light sources in vehicle head lamps F21S41/657
• CPC Class Codes: F21V 5/10 comprising photoluminescent material
• CPC Class Codes: F21V 9/30 Elements containing photoluminescent material distinct from or spaced from the light source shades F21V1/17; globes, bowls or cover glasses F21V3/08, F21V3/12; refractors F21V5/10; reflectors F21V7/26, F21V7/30; elements with provision for controlling the spectral properties or intensity F21V9/40
• CPC Class Codes: G01N 21/59 Transmissivity G01N21/25 takes precedence
• CPC Class Codes: G01N 2201/105 Purely optical scan
• CPC Class Codes: G02B 27/18 for optical projection, e.g. combination of mirror and condenser and objective photographic, cine and overhead projectors G03B21/00; photographic projection printing G03B27/32; photolithographic projectors G03F7/20; projection television H04N5/74; colour projection television H04N9/31
• CPC Class Codes: G02B 5/18 Diffraction gratings holographic optical elements G02B5/32, G03H; integrally combined with optical fibres G02B6/02057; for coupling light guides G02B6/34; integrally combined with optical integrated light guides G02B6/12; grating systems G02B27/44
• CPC Class Codes: G02B 5/1866 Transmission gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials G02B5/1809, G02B5/1828, G02B5/1833, G02B5/1838 and G02B5/1847 take precedence
• CPC Class Codes: G02B 6/0003 the light guides being doped with fluorescent agents
• CPC Class Codes: G02B 6/1226 involving surface plasmon interaction
• CPC Class Codes: G02B 6/124 Geodesic lenses or integrated gratings
• CPC Class Codes: G03B 21/204 using secondary light emission, e.g. luminescence or fluorescence using different colours G03B33/00; if related to video signals H04N9/3197

Abstract

a light-emitting device including: a photoluminescent layer that contains a photoluminescent material and emits light including first light having a wavelength λ_a in air; and a light-transmissive layer located on or near the photoluminescent layer. At least one periodic structure is defined on at least one of the photoluminescent layer and the light-transmissive layer. The at least one periodic structure has projections or recesses or both. A distance D_int between two adjacent projections or two adjacent recesses and a refractive index n_wav-a of the photoluminescent layer for the first light satisfy λ_a/n_wav-a<D_int<λ_a. A wavelength A of a peak intensity in a spectrum of light output from the at least one periodic structure in a direction perpendicular to the photoluminescent layer is different from a wavelength B of a peak intensity in an emission spectrum of the photoluminescent material.

Claims

1. A light-emitting device comprising:

a photoluminescent layer that contains a photoluminescent material and emits light including first light having a wavelength λ

_a in air; and

a light-transmissive layer located on or near the photoluminescent layer, wherein

at least one periodic structure is defined on at least one of the photoluminescent layer and the light-transmissive layer,

the at least one periodic structure has projections or recesses or both,

a distance D_int between two adjacent projections or two adjacent recesses and a refractive index n_wav-a of the photoluminescent layer for the first light satisfy λ

_a/n_wav-a<

D_int<

λ

_a,

a wavelength A of a peak intensity in a spectrum of light output from the at least one periodic structure in a direction perpendicular to the photoluminescent layer is different from a wavelength B of a peak intensity in an emission spectrum of the photoluminescent material, and

the at least one periodic structure has a period that allows an electric field to be formed in the photoluminescent layer, in which a period of maximum amplitude of the electric field is the same as the period of the at least one periodic structure.

2. The light-emitting device according to claim 1, wherein the wavelength A is longer than the wavelength B.

3. The light-emitting device according to claim 1, wherein

the wavelength A is different from the wavelength B by at least a half width at half maximum HWHM of the emission spectrum of the photoluminescent material.

4. The light-emitting device according to claim 1, wherein

there are two wavelengths at which the emission spectrum of the photoluminescent material has half the peak intensity, and

a difference between the wavelength A and the wavelength B is greater than or equal to a difference W between the wavelength B and a wavelength C, the wavelength C being one of the two wavelengths having a greater difference from the wavelength B.

5. The light-emitting device according to claim 1, wherein the wavelength λ

_a is identical to the wavelength A.

8. The light-emitting device according to claim 1, wherein the photoluminescent layer is in contact with the light-transmissive layer.

10. A light-emitting apparatus comprising:

the light-emitting device according to claim 1; and

an optical shutter having light-transmissive regions, wherein

each of the light-transmissive regions is located on corresponding one of optical paths of light beams emitted in different directions from the light-emitting device, and

the optical shutter changes a light transmittance of each light-transmissive region independently.

11. A projector comprising:

the light-emitting apparatus according to claim 10; and

an optical system that converges light emitted from the optical shutter.

12. A light-emitting apparatus comprising:

the light-emitting device according to claim 1; and

an optical filter that has a light-transmissive region that transmits a light beam emitted in a particular direction from the light-emitting device.

13. The light-emitting apparatus according to claim 12, wherein

the optical filter includes a plurality of light-transmissive regions including the light-transmissive region, and

the plurality of light-transmissive regions transmit light beams emitted in particular directions from the light-emitting device.

14. The light-emitting apparatus according to claim 12, wherein

the light-emitting device emits light beams having different wavelengths, and

the light-emitting apparatus further comprises a mechanism that turns the light-emitting device, allowing the light beams to pass through the light-transmissive region.

15. The light-emitting apparatus according to claim 12, wherein

the light-emitting device emits light beams having different wavelengths, and

the light-emitting apparatus further comprises a mechanism that moves the optical filter in a direction across the light beams, allowing the light beams to pass through the light-transmissive regions.

16. A detecting apparatus comprising:

the light-emitting device according to claim 1; and

a detector that is located on an optical path of the light emitted from the photoluminescent layer and detects a target.

17. The detecting apparatus according to claim 16, further comprising a holder that holds the target on the optical path between the light-emitting device and the detector.

18. The detecting apparatus according to claim 16, further comprising an optical filter located on the optical path and has a light-transmissive region that transmits a light beam emitted in a particular direction from the light-emitting device.

19. The light-emitting device according to claim 1, wherein the photoluminescent layer has a thickness that allows a quasi-guided mode to be formed within the photoluminescent layer.

23. The light-emitting device according to claim 1, wherein a distance between the light-transmissive layer and the photoluminescent layer is equal to or less than λ

_a/2.

6. A light-emitting device comprising:

a light-transmissive layer having at least one periodic structure defined thereon; and

a photoluminescent layer that is located on or near the at least one periodic structure and contains a photoluminescent material and emits light including first light having a wavelength λ

_a in air, wherein,

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

_a/n_wav-a<

p_a<

λ

_a,

a wavelength A of a peak intensity in a spectrum of light output from the at least one periodic structure in a direction perpendicular to the photoluminescent layer is different from a wavelength B of a peak intensity in an emission spectrum of the photoluminescent material, and

the at least one periodic structure has a period that allows an electric field to be formed in the photoluminescent layer, in which a period of maximum amplitude of the electric field is the same as the period of the at least one periodic structure.

20. The light-emitting device according to claim 6, wherein the photoluminescent layer has a thickness that allows a quasi-guided mode to be formed within the photoluminescent layer.

24. The light-emitting device according to claim 6, wherein a distance between the light-transmissive layer and the photoluminescent layer is equal to or less than λ

_a/2.

7. A light-emitting device comprising:

a photoluminescent layer that contains a photoluminescent material and emits light including first light having a wavelength λ

_a in air; and

a light-transmissive layer having a higher refractive index for the first light than the photoluminescent layer;

wherein

at least one periodic structure is defined on the light-transmissive layer,

the at least one periodic structure has projections or recesses or both,

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

_a/n_wav-a<

p_a<

λ

_a,

a wavelength A of a peak intensity in a spectrum of light output from the at least one periodic structure in a direction perpendicular to the photoluminescent layer is different from a wavelength B of a peak intensity in an emission spectrum of the photoluminescent material, and

the at least one periodic structure has a period that allows an electric field to be formed in the photoluminescent layer, in which a period of maximum amplitude of the electric field is the same as the period of the at least one periodic structure.

21. The light-emitting device according to claim 7, wherein the photoluminescent layer has a thickness that allows a quasi-guided mode to be formed within the photoluminescent layer.

9. A light-emitting device comprising a photoluminescent layer that contains a photoluminescent material and emits light including first light having a wavelength λ

_a in air;

wherein

at least one periodic structure is defined on the photoluminescent layer,

the at least one periodic structure has projections or recesses or both,

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

_a/n_wav-a<

p_a<

λ

_a,

a wavelength A of a peak intensity in a spectrum of light output from the at least one periodic structure in a direction perpendicular to the photoluminescent layer is different from a wavelength B of a peak intensity in an emission spectrum of the photoluminescent material, and

the at least one periodic structure has a period that allows an electric field to be formed in the photoluminescent layer, in which a period of maximum amplitude of the electric field is the same as the period of the at least one periodic structure.

22. The light-emitting device according to claim 9, wherein the photoluminescent layer has a thickness that allows a quasi-guided mode to be formed within the photoluminescent layer.