Patent ID: 8134311

Claim:
A light source for generating light having a spectral emittance in at least a part of the range of 380 nm to 780 nm, the light having a spectral power distribution E(λ) as a function of the wavelength λ, and a general color-rendering index R a , wherein the ratio of the integral spectral power distribution over a first range of 575 nm≦λ≦650 nm to that of a second range of 380 nm≦λ≦780 nm is given by the relation: ∫ 575 650 ⁢ E ⁡ ( λ ) ⁢ ⅆ λ ∫ 380 780 ⁢ E ⁡ ( λ ) ⁢ ⅆ λ = B b , and wherein 0<B b ≦0.15 and R a ≧20.