| 摘要 |
An extinct type detector which detects and determines a concentration or density of a gas or vapor in a space on the basis of an attenuation of light due to the gas or vapor present within the space. The detector of this feature of the invention operates in such a way that the light emitting device is periodically driven to effect light emission, the first and the second photodetector devices receive the light from said light emitting device, the first and second storage means corresponding to the first and the second photodetector devices, respectively, cumulatively store the outputs from the respective photodetector devices, a difference in cumulative storage values between the first and the second storage means is detected to determine a concentration and density of the gas or vapor within the detecting space based on the detected difference. |
