Illuminating device

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 Fex(λ) is a spectrum of the light emitted from the semiconductor light emitting element, limited to a case where Fex(π) is measurable or predetermined, FLED(λ) is a spectrum of a light emitted from the luminescent device, and xLED and yLED are CIE trichromatic coordinate values obtained from the spectrum FLED(λ), and
• given that xd and yd are CIE trichromatic coordinate values obtained from a differential spectrum Fd(λ) determined by a formula (IV) described below as subtracting said spectrum Fex(λ) from said spectrum FLED(λ):
• Fd(λ)=FLED(λ)−nFex(λ) (IV)
• in which n is a value for normalization so that a peak value of Fex(λ) is equal to a peak value of a light spectrum component from the semiconductor light emitting element present in the spectrum FLED(λ),
• the excitation light contribution ratio ΔE being a value determined by a formula (V):
• ΔE=√{square root over ((xLED−xd)2+(yLED−yd)2)}{square root over ((xLED−xd)2+(yLED−yd)2)} (V).