| 摘要 |
PURPOSE:To exactly detect the oxygen concn. in air by connecting an output resistance to a galvanic cell and providing a PTC heater having a constant temp. exothermic effect for heat insulation near the galvanic cell. CONSTITUTION:A fixed resistor 4 as the output resistance is parallel connected to the galvanic cell 1 and the PTC heater 5 having the constant temp. exothermic effect for heat insulation is provided near the cell 1. The heater 5 exhibits RaOMEGA, RbOMEGA at the point of the time when the temp. is, for example, 0 deg.C and 50 deg.C if a voltage is impressed to the heater 5. The ambient temp. of the cell 1 can, therefore, be maintained at 50 deg.C by the self control of the heater 5. Since the cell 1 is maintained always in the heat insulated state in the above- mentioned manner, the cell is not affected by the ambient temp. and the specified diffusion current corresponding to 50 deg.C flows through the resistor 4. The output voltage is maintained constant in, for example, the -20-50 deg.C range of the ambient temp. if the oxygen concn. is constant. The oxygen concn. in the air is thus exactly detected. |
