Light emitting device

1. A light emitting device, comprising:

an excitation light source that emits excitation light;

a wavelength conversion member that absorbs the excitation light emitted from the excitation light source, converts its wavelength, and releases light of a predetermined wavelength band; and

a light guide in which the center part of its cross section has a refractive index that is higher than the refractive index of the peripheral portion, and which guides the excitation light emitted from the excitation light source to the wavelength conversion member,

wherein the wavelength conversion member being produced by laminating a plurality of layers that convert different wavelengths of light.

2. The light emitting device according to claim 1 , wherein the distal end of the light guide on the wavelength conversion member side is supported by a light guide distal end member, and the light guide distal end member is formed from a material that reflects at least one of the excitation light and the light that has undergone wavelength conversion.

3. The light emitting device according to claim 2 , wherein the wavelength conversion member, along with the end of the light guide, covers all or part of the end of the light guide distal end member.

4. The light emitting device according to claim 2 , wherein at least one of the light guide distal end member and the light guide has an end face for mirror surface reflection or scattered reflection, or an end face that has an uneven surface.

5. The light emitting device according to claim 1 , wherein the light guide is such that the diameter of the center part of its cross section is formed larger only at the end on the wavelength conversion member side.

6. The light emitting device according to claim 1 , further comprising at least one of

a wavelength-converted light reflecting film provided to the portion of the wavelength conversion member into which excitation light is guided, and

an excitation light reflecting film provided to the portion of the wavelength conversion member from which wavelength-converted light is guided.

7. The light emitting device according to claim 1 , wherein a scatter preventing member is formed at least one of between the wavelength conversion member and the light guide, and on the surface of the wavelength conversion member except for the portion from which wavelength-converted light is guided to the outside.

8. The light emitting device according to claim 1 , comprising a plurality of light guides.

9. The light emitting device according to claim 1 , further comprising a lens between the excitation light source and the light guide, wherein the excitation light emitted from the excitation light source is guided into the light guide via the lens.

10. The light emitting device according to claim 1 , further having a shielding member that blocks at least 90% of the light from the excitation light source.

11. The light emitting device according to claim 1 , wherein the wavelength conversion member has, from the side closest to the excitation light source, at least a first layer having a first fluorescent substance, and a second layer having a second fluorescent substance,

the second fluorescent substance is excited by the excitation light from the excitation light source, and

the first fluorescent substance is excited by light from the second fluorescent substance.

12. The light emitting device according to claim 1 , wherein the wavelength conversion member has, from the side closest to the excitation light source, at least a first layer having a first fluorescent substance, and a second layer having a second fluorescent substance,

the first fluorescent substance produces less heat caused by excitation light than that of the second fluorescent substance.

13. A light emitting device comprising:

an excitation light source that emits excitation light;

a wavelength conversion member that absorbs the excitation light emitted from the excitation light source, converts its wavelength, and releases light of a predetermined wavelength band; and

a light guide in which the center part of its cross section has a refractive index that is higher than the refractive index of the peripheral portion, and which guides the excitation light emitted from the excitation light source to the wavelength conversion member,

the wavelength conversion member being made of a mixture of two or more types of fluorescent materials.

14. The light emitting device according to claim 13 , wherein the wavelength conversion member includes one of

a combination of (Sr,Ca) 5 (PO 4 ) 3 Cl:Eu, one of LAG and BaSi 2 O 2 N 2 :Eu, and SCESN,

a combination of YAG and one of CCA, CCB and BAM, and

a combination of one of CCA, CCB and BAM, LAG, and SCESN arranged in this order from the light incidence side.

15. The light emitting device according to claim 13 , wherein the fluorescent materials include at least one of

Y 3 Al 5 O 12 :Ce,

(Y 0.8 Gd 0.2 ) 3 Al 5 O 12 :Ce,

Y 3 (Al 0.8 Ga 0.2 ) 5 O 12 :Ce,

(Y,Gd) 3 (Al,Ga) 5 O 12 :Ce,

Y 3 (Al,Sc) 5 O 12 :Ce,

Lu 3 Al 5 O 12 :Ce,

Tb 3 Al 5 O 12 :Ce, and

Gd 3 (Al,Ga) 5 O 12 :Ce.

16. The light emitting device according to claim 13 , wherein the fluorescent materials include a combination of YAG and at least one of CCA, CCB and BAM.

17. The light emitting device according to claim 13 , wherein the fluorescent materials have a particle size in the range of approximately 1 μm to 20 μm.

18. The light emitting device according to claim 13 , wherein the wavelength conversion member contains a filler.

19. The light emitting device according to claim 13 , wherein a scatter preventing member is formed at least one of between the wavelength conversion member and the light guide, and on the surface of the wavelength conversion member except for the portion from which wavelength-converted light is guided to the outside.

20. The light emitting device according to claim 14 , wherein the excitation light source has a light emission peak wavelength within a range from 360 to 470 nm.