Light Emitting Device, and Lighting System, Image Display Using the Same

Abstract

To enhance luminance and color rendering of a light emitting device comprising phosphors as wavelength converting material and at least one semiconductor light emitting device that emits visible light, as said phosphors, are used phosphors which are one or more kinds of phosphors selected from a group consisting of oxides, oxynitrides and nitrides, and are a mixture consisting of two or more kinds of phosphors whose luminous efficiency is 35% or higher when excited by the visible light from said semiconductor light emitting device at room temperature. In addition, said mixture contains a first phosphor, and a second phosphor that is different from said first phosphor and capable of absorbing emitted light from said first phosphor, and said first phosphor is contained 85 weight % or more of said mixture of phosphors.

1 . A light emitting device comprising:
 phosphors as wavelength converting material and   at least one semiconductor light emitting device that emits visible light,   wherein said phosphors are one or more kinds of phosphors selected from a group consisting of oxides oxynitrides and nitrides, and are a mixture consisting of two or more kinds of phosphors whose luminous efficiency is 35% or higher when excited by the visible light from said semiconductor light emitting device at room temperature; and   said mixture contains a first phosphor, and a second phosphor that is different from said first phosphor and capable of absorbing emitted light from said first phosphor and said first phosphor is contained 85 weight % or more of said mixture of phosphors.   
   
   
       2 . A light emitting device as defined in  claim 1 , wherein the mission peak wavelength L 1  of said first phosphor is in the range of 490 nm≦L 1 ≦550 nm and the emission peak wavelength L 2  of said second phosphor is in the range of 600 nm≦L 2 ≦700 nm. 
   
   
       3 . A light emitting device as defined in  claim 1 , wherein the device contains a mixture of phosphors whose color coordinate (x, y) of the emitted light from said mixture of phosphors, when it is irradiated by the emitted light from said semi conductor light emitting device, is in the range surrounded by the quadrangle with apexes having CIE color coordinates (0.450, 0.350), (0.550, 0.450), (0.400, 0.600), and (0.300, 0.500). 
   
   
       4 . A light emitting device as defined in  claim 1 , wherein the color coordinate of a composite light consisting of emitted light from said semiconductor light emitting device and emitted light from said mixture of phosphors that is excited by the emitted light from said semiconductor light emitting device, is in the range surrounded by the quadrangle with apexes having CIE color coordinates (0.275, 0.175), (0.450, 0.400), (0.350, 0.450), and (0.175, 0.250). 
   
   
       5 . A lighting system wherein said lighting system uses said light emitting device as defined in  claim 1 . 
   
   
       6 . A display, wherein said display uses said light emitting device as defined in  claim 1 .