Light emitting device

Abstract

Provided is a light emitting device with effectively improved color rendering properties. A light emitting device 1 includes: a light source 2 that emits light having the maximum intensity at a predetermined wavelength; a first phosphor (yellow phosphor) 51 that absorbs the light emitted by the light source 2 and outputs fluorescent light having the maximum intensity at a first wavelength which is longer than the predetermined wavelength; and a second phosphor (red phosphor) 52 that absorbs the light emitted by the light source 2 and outputs fluorescent light having the maximum intensity at a second wavelength which is longer than the first wavelength. An absolute value of wavelength dependency of an optical absorption rate of the second phosphor 52 at the first wavelength is set to not more than 0.6%/nm. Accordingly, the color rendering properties of the light emitted by the light emitting device 1 can be effectively improved.

What is claimed: 
     
         1 . A light emitting device comprising:
 a LD (Laser Diode) light source that emits light having a maximum intensity at a predetermined wavelength;   a first phosphor that absorbs the light emitted by the light source and outputs fluorescent light having a maximum intensity at a first wavelength which is longer than the predetermined wavelength; and   a second phosphor that absorbs the light emitted by the light source and outputs fluorescent light having a maximum intensity at a second wavelength which is longer than the first wavelength.   
     
     
         2 . The light emitting device according to  claim 1 , wherein the predetermined wavelength is not shorter than 420 nm and not longer than 480 nm. 
     
     
         3 . The light emitting device according to  claim 1 , wherein
 the first wavelength is not shorter than 500 nm and not longer than 580 nm, and   the second wavelength is not shorter than 600 nm and not longer than 680 nm.   
     
     
         4 . The light emitting device according to  claim 2 , wherein the first phosphor is a phosphor added with Ce as an activator. 
     
     
         5 . The light emitting device according to  claim 4 , wherein the first phosphor is represented by a composition formula of Y 3 Al 5 O 12  including substances obtained by replacing part or all of Y, Al and O of the composition formula with predetermined elements. 
     
     
         6 . The light emitting device according to  claim 2 , wherein the second phosphor is a phosphor added with Eu as an activator. 
     
     
         7 . The light emitting device according to  claim 6 , wherein the second phosphor is represented by a composition formula of CaAlSiN 3  including substances obtained by replacing part or all of Ca, Al, Si and N of the composition formula with predetermined elements. 
     
     
         8 . The light emitting device according to  claim 3 , wherein the first phosphor is a phosphor added with Ce as an activator. 
     
     
         9 . The light emitting device according to  claim 8 , wherein the first phosphor is represented by a composition formula of Y 3 Al 5 O 12  including substances obtained by replacing part or all of Y, Al and O of the composition formula with predetermined elements. 
     
     
         10 . The light emitting device according to  claim 3 , wherein the second phosphor is a phosphor added with Eu as an activator. 
     
     
         11 . The light emitting device according to  claim 10 , wherein the second phosphor is represented by a composition formula of CaAlSiN 3  including substances obtained by replacing part or all of Ca, Al, Si and N of the composition formula with predetermined elements.