Importance

Loading Importance Indicators...

Abstract

A two-wavelength type respiratory gas concentration measuring device includes a connector tube which is held in the mouth of an examinee and which has airtight windows, a light source which applies infrared rays through the windows of the connector tube, and first and second filters. The first filter allows the transmission of a light component whose wavelength is such that it is absorbed by the respiratory gas, and the second filter allows the transmission of a light component whose wavelength is such that it is not absorbed by the respiratory gas. A photodetector converts the infrared rays transmitted through the filters into an electric signal. A first detector receives the electric signal and detects the light output of the first filter. A second detector receives the electric signal and detects the light output of the second filter. A power computing circuit performs a power computation of the output of the second detector with a power exponent m. A divider circuit divides the output of the first detector by the output of the first power computing circuit. A DC level detector detects the DC level of the photodetector when no infrared rays are applied. A second power computing circuit performs a power computation of the output of the DC-level detector with a power exponent of 2(m-1). A multiplier circuit multiplies the output of the second power computing circuit by the output of the divider.

Loading the Abstract Image...

First Claim