Patent ID: 8471459

Claim:
A fluorescent substance represented by the following formula (1): (M 1−x EC x ) a Si b AlO c N d (1) in which M is Sr; EC is Eu; and x, a, b, c and d are numbers satisfying the conditions of 0<x<0.4, 0.55<a<0.80, 2<b<3, 0<c≦0.6 and 4<d<5, respectively; in the form of crystals whose mean grain size is in the range of 20 to 100 μm and whose aspect ratio is in the range of 2 to 4; and emitting luminescence having a peak in the wavelength range of 580 to 660 nm under excitation by light in the wavelength range of 250 to 500 nm.