Patent ID: 7098586

Claim:
A light source comprising: a fluorescent lamp having a phosphor layer with at least 70% by weight of the phosphor layer being a combination of: a phosphor containing bivalent europium as an emission center and having a peak emission at a wavelength range of 440 nm to 470 nm; a phosphor containing bivalent manganese as an emission center and having a peak emission at a wavelength range of 505 nm to 530 nm; a phosphor containing trivalent terbium as an emission center and having a peak emission at a wavelength range of 540 nm to 570 nm; and a phosphor containing trivalent europium as an emission center and having a peak emission at a wavelength range of 600 nm to 620 nm; whereby the light emitted has a whiteness no smaller than 85 with a visual clarity index no smaller than 110, the whiteness W being calculated according to the equation: W=− 5.3 C+ 100 where C is chroma of the light calculated as defined by the CIE 1997 Interim Color Appearance Model (simple version); and the ratio of radiant energy Qv to radiant energy Qg satisfies an inequality for a correlated color temperature T (K): Qg/Qv≧− 0.11×10 4 /T+ 0.30 where Qg is radiant energy with a wavelength in the range of 505 nm to 530 nm, and Qv is radiant energy with a wavelength in the range of 380 nm to 780 nm.