Limiting electric current type oxygen concentration detector applied with temperature compensation

Claim 1

A limiting electric current type oxygen concentration detector comprising: (a) a limiting electric current type oxygen concentration sensor comprising; an oxygen ionic conductor having opposite surfaces, a cathode placed on one surface of said oxygen ionic conductor, and an anode placed on the other surface of said oxygen ionic conductor to supply a predetermined voltage, a member covering at least the surface of said cathode to regulate the quantity of oxygen gas which diffuses toward said cathode, (b) a first means including first and second power supply means for respectively electrically driving said limiting electric current type oxygen concentration sensor, the first power supply means producing limiting current flow in said sensor, said second power supply means producing current flow in said sensor in a resistance domination range thereof in which current flow is proportional to the internal resistance of the sensor, (c) a second means for detecting the magnitude of said limiting current flow in said sensor and an electrical quantity which is proportional to the magnitude of said internal resistance, (d) a third means for alternately connecting said first and second power supply means to said sensor for respective first and second periods of time, said second means measuring limiting current in said sensor during said first period of time and measuring said electrical quantity during said second period of time which is a measure of the internal resistance of the sensor, (e) a fourth means connected to the output of the second means for producing an output signal representing a temperature correction coefficient from the formula ##EQU18## based on said electrical quantity, and (f) a fifth means connected to said second means and said fourth means for multiplying the output of the second means indicating limiting current of the sensor by the output α(T) of the fourth means.