Patent ID: 8021576

Claim:
A phosphor having an elemental ratio represented by the formula [1] M 1 a M 2 b M 3 c O d [1] (In the formula [1], M 1 represents at least one element selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm and Yb, M 2 mainly represents a bivalent metal element, M 3 mainly represents a trivalent metal element, a represents a number in the range of 0.0001≦a≦0.2, b represents a number in the range of 0.8≦b≦1.2, c represents a number in the range of 1.6≦c≦2.4, and d represents a number in the range of 3.2≦d≦4.8), and containing at least two elements selected from the group consisting of Li, Na, K, Rb, Cs, P, Cl, F, Br, I, Zn, Ga, Ge, In, Sn, Ag, Au, Pb, Cd and Bi, wherein at least one of the following (1) through (3) applies: (1) wherein emitting light at room temperature and having a crystal phase of CaFe 2 O 4 -type crystal structure, the percentage of the number of the phosphor particles of which average circularity is smaller than 85% being 10% or less, (2) wherein emitting light at room temperature and having a crystal phase of CaFe 2 O 4 -type crystal structure and weight-average median diameter D 50 of 10 μm or larger, the value QD, represented by the equation, “QD=(D 75 −D 75 )/(D 75 +D 25 )”, where D 25 and D 75 are the values of the particle diameter in the weight-standard particle size distribution curve at integrated values of 25% and 75% respectively, being 0.27 or smaller, (3) wherein having the maximum emission peak in the wavelength range of from 485 nm to 555 nm and a crystal phase of CaFe 2 O 4 -type crystal structure, wherein the percentage of the number of the particles of which aspect ratio is 3 or smaller is 60% or more.