Patent ID: 7294956
Filing Date: 2007-11-13
Classification: C09K,H01L,Y02E

Abstract:
1. A semiconductor light emitting device for emitting white-based light having a luminescent chromaticity point (x, y) in the CIE chromaticity diagram of 0.21≦x≦0.48 and 0.19≦y≦0.45, comprising a combination of: a near ultraviolet light emitting element for emitting light having an emission peak in a wavelength region exceeding 350 nm and not more than 410 nm; and a phosphor layer including a plurality of phosphors for absorbing near ultraviolet emitted by said near ultraviolet light emitting element and for emitting fluorescence having an emission peak in a visible wavelength region not less than 380 nm and not more than 780 nm, wherein said phosphor layer includes four kinds of phosphors: a blue-based phosphor for emitting blue-based fluorescence having an emission peak in a wavelength region not less than 400 mm and less than 500 nm; a green-based phosphor for emitting green-based fluorescence having an emission peak in a wavelength region not less than 500 nm and less than 550 nm; a red-based phosphor for emitting red-based fluorescence having an emission peak in a wavelength region not less than 600 nm and less than 660 nm; and a yellow-based phosphor for emitting yellow-based fluorescence having an emission peak in a wavelength region not less than 550 nm and less than 600 nm, and wherein said yellow-based phosphor is a silicate phosphor having an orthorhombic crystal structure and principally including a compound represented by the following chemical formula: wherein a1, b1 and x are numerical values satisfying 0≦a1≦0.3, 0≦b1≦0.8, 0<x<1.