Patent ID: 7427365

Claim:
A phosphorescent phosphor comprising a compound having a SrAl 2 O 4 crystal structure as a matrix, europium (Eu) doped to said matrix as an activator, and dysprosium (Dy) doped to said matrix as a co-activator; an amount of said doped europium (Eu) being more than 1.5% and not more than 5% in terms of mol % relative to a total mole number of strontium (Sr), europium (Eu) and dysprosium (Dy); an amount of said doped dysprosium (Dy) ranging 0.4≦Dy/Eu≦2 in terms of a molar ratio relative to europium (Eu); and a ratio of aluminum (Al) ranging from 2.02 to 2.4 in terms of a molar ratio relative to a total mole number of strontium (Sr), europium (Eu) and dysprosium (Dy).