| 摘要 |
PROBLEM TO BE SOLVED: To provide an oxygen saturation degree measuring device which has a high measuring accuracy even in a relatively low oxygen-saturation-degree range, e.g. 80% or less. SOLUTION: The wavelength of light output from a first light emission element 18 is set in the range from 715 to 770 nm as a first wavelengthλ1 at which absorption coefficient varies according to the degree of oxygen saturation of blood, and a second wavelengthλ2 is set in the range from 880 to 940 nm; because the wavelengthλ1 is shorter than the second wavelengthλ2 , it is more likely to be scattered, and light of the wavelengthλ1 can fully reach a blood vessel floor where capillaries exist. Therefore, since a broken line showing the actual degree of oxygen saturation SaO2 and a rectilinear approximate line indicated by the true line are approximate to each other even in a relatively low oxygen saturation degree region, the accuracy of the degree of oxygen saturation SaO2 of a living body, calculated from a predetermined relationship and on the basis of the ratio R of the alternate-to-direct component ratio (AC/DC)R of a first light signal to the alternate-to-direct component ratio (AC/DC)IR of a second light signal by an oxygen saturation degree calculation means 74 which uses the rectilinear approximate line as the preset relationship, is enhanced favorably.
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