Light-emitting device
View Patent ↗A light-emitting device includes a radiation source that radiates laser light as first primary light, and a first wavelength converter, and emits output light. The first wavelength converter has an incidence face on which the first primary light is incident, and an emission face through which the output light emits. A normal to the incidence face and a normal to the emission face are mutually different. A first phosphor included in the first wavelength converter is a single crystal phosphor.
1. A light-emitting device that emits output light, the light-emitting device comprising:
a radiation source that radiates laser light as first primary light;
a first wavelength converter; and
a second wavelength converter that includes a second phosphor,
wherein
the first wavelength converter includes at least a first phosphor,
the first wavelength converter scatters at least part of the first primary light and converts into second primary light that propagates in a direction different from an optical-axis direction of the first primary light,
the first phosphor included in the first wavelength converter absorbs at least part of the first primary light and the second primary light and converts into secondary light that has more long-wavelength components than a wavelength component of at least one of the first primary light or the second primary light,
the output light includes the second primary light and the secondary light,
the first wavelength converter has an incidence face on which the first primary light is incident and an emission face through which the output light emits, and a normal to the incidence face and a normal to the emission face are mutually different,
the first phosphor is a single crystal phosphor,
the second phosphor included in the second wavelength converter absorbs at least part of the second primary light and the secondary light, and emits tertiary light, and
the output light includes the tertiary light.
2. The light-emitting device according to claim 1 , wherein the first phosphor has a garnet crystal structure.
3. The light-emitting device according to claim 2 , wherein
the radiation source emits bluish light as the first primary light, and
the first phosphor is a Ce 3+ -activated phosphor.
4. The light-emitting device according to claim 1 , wherein the first phosphor emits, as the secondary light, light having a spectrum indicating a maximum peak intensity in a wavelength range of at least 480 nm and at most 600 nm.
5. The light-emitting device according to claim 1 , wherein the second phosphor emits, as the tertiary light, light having a spectrum indicating a maximum peak intensity in a wavelength range of at least 480 nm and at most 660 nm.
6. The light-emitting device according to claim 1 , wherein the spectrum of the light emitted by the second phosphor is different from the spectrum of the light emitted by the first phosphor.
7. The light-emitting device according to claim 1 , wherein a principal component of the spectrum of the light emitted by the second phosphor contains more long-wavelength components than a principal component of the spectrum of the light emitted by the first phosphor.
8. The light-emitting device according to claim 1 , wherein the spectrum of the light emitted by the first phosphor is identical to the spectrum of the light emitted by the second phosphor.
9. The light-emitting device according to claim 1 , wherein the second phosphor is a Ce 3+ -activated phosphor.
10. The light-emitting device according to claim 1 , wherein the second phosphor is either a nitride phosphor or an oxynitride phosphor that emits reddish light having a spectrum indicating a maximum peak intensity in a wavelength range of at least 600 nm and at most 660 nm.
11. The light-emitting device according to claim 10 , wherein the second phosphor is a compound having a crystal structure identical to a crystal structure of CaAlSiN 3 .
12. The light-emitting device according to claim 1 , wherein the first wavelength converter has a structure in which the first phosphor is sealed by at least one of a light transmissive resin material or a light transmissive inorganic material.
13. The light-emitting device according to claim 1 , wherein the second wavelength converter has a structure in which the second phosphor is sealed by at least one of a light transmissive resin material or a light transmissive inorganic material.
14. The light-emitting device according to claim 1 , wherein a correlated color temperature of the output light is at least 2000 K and at most 20000 K.
15. The light-emitting device according to claim 1 , wherein average color rendering index Ra of the output light is at least 80 and at most 100.
16. The light-emitting device according to claim 1 , wherein
the first wavelength converter includes a reflector on at least one face other than the emission face, and
directions in which at least part of the first primary light, the second primary light, and the secondary light propagate inside the first wavelength converter are controlled by the reflector.
17. The light-emitting device according to claim 1 , wherein the first primary light is incident on the incidence face in a direction approximately vertical to the incidence face of the first wavelength converter.
18. The light-emitting device according to claim 1 , wherein the first wavelength converter has a flat plate shape.
19. The light-emitting device according to claim 18 , wherein
the first primary light is incident on the incidence face in a direction approximately vertical to a thickness direction of the first wavelength converter, and
the output light emits through the emission face in a direction approximately parallel to the thickness direction of the first wavelength converter.
20. The light-emitting device according to claim 1 , wherein the first primary light emitted from the radiation source is radiated on the first wavelength converter via an optical waveguide.