Patent ID: 8710741

Claim:
An illuminating device comprising: one or more luminescent devices, comprising a semiconductor light emitting element emitting a light with a first emission spectrum having an emission peak within a wavelength range from 380 nm to 430 nm, and a luminescent part comprising a sealing member and phosphors 1 to 3, absorbing at least part of light with the first emission spectrum and emitting a light with another emission spectrum different from the first emission spectrum, wherein an excitation light contribution ratio ΔE as defined below is 0.005 or less, and a mean color rendering index Ra is 70 or more; phosphor 1: a phosphor having a wavelength of a major emission peak from 430 nm to 500 nm, phosphor 2: a phosphor having a wavelength of a major emission peak from 500 nm to 580 nm, phosphor 3: a phosphor having a wavelength of a major emission peak from 580 nm to 700 nm, the excitation light contribution ratio: given that F ex (λ) is a spectrum of the light emitted from the semiconductor light emitting element, limited to a case where F ex (π) is measurable or predetermined, F LED (λ) is a spectrum of a light emitted from the luminescent device, and x LED and y LED are CIE trichromatic coordinate values obtained from the spectrum F LED (λ), and given that x d and y d are CIE trichromatic coordinate values obtained from a differential spectrum F d (λ) determined by a formula (IV) described below as subtracting said spectrum F ex (λ) from said spectrum F LED (λ): F d (λ)= F LED (λ)− nF ex (λ) (IV) in which n is a value for normalization so that a peak value of F ex (λ) is equal to a peak value of a light spectrum component from the semiconductor light emitting element present in the spectrum F LED (λ), the excitation light contribution ratio ΔE being a value determined by a formula (V): Δ E =√{square root over (( x LED −x d ) 2 +( y LED −y d ) 2 )}{square root over (( x LED −x d ) 2 +( y LED −y d ) 2 )} (V).