| 摘要 |
PURPOSE:To detect the abnormality in the optical system of a measuring device for gas concn., the decrease in the function of its light source, the condensation therein, etc. by utilizing the signal obtainable with the operation of said device. CONSTITUTION:When abnormality arises in an optical system, a voltage VREF decreases and the output of a comparator 20 changes to H. The entire input to an AND gate 21 goes to an H, then the H appears at an output terminal 27 and an alarm device not shown in the figure is driven. When the discharge output from a laser tube 1 decreases, the output of a comparator 23 changes to an L on account of a decrease in a signal VIL. Since the signal VREF decreases at the same instant in this stage, the output of the comparator 20 goes to an H and therefore the entire input to an AND gate 22 goes to an H, then the H signal appears at an output terminal 28 and a decrease in the function of a light source is alarmed. When the discharge of the tube 1 stops, the output of a comparator 25 goes to an L, and the H signal appears at an output terminal 29 via an invertor 30, by which the stop of the discharge is alarmed. When only the condensation arises and a sensor 26 goes to an L, the condensation is alarmed by the signals L, L of the terminals 27, 29. |
