Oxygen concentration-sensing device

• Main Authors: MIENO; TOSHIYUKI, NAKAJIMA; TOYOHEI
• Format: Patent
• Language: English
• Published: 31.10.1989
• Subjects: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; MEASURING; PHYSICS; TESTING

An oxygen concentration-sensing device includes an oxygen concentration-sensing element formed by an oxygen-pumping element and a cell element, each composed of an oxygen ion-conductive electrolytic member and a pair of electrodes having the member interposed therebetween. The two elements define a gas diffusion-limiting zone therebetween. A current-to-voltage converter circuit has an input terminal connected to the junction between mutually connected ones of the electrodes. A first amplifier generates an output having a level variable in response to the difference between a potential at a conversion output terminal of the current-to-voltage converter circuit and a potential at the other electrode of the cell element, and applies the output to the other electrode of the oxygen-pumping element. A second amplifier has an input thereof connected to the above junction and generates an output proportional to current flowing in the oxygen-pumping element. The current-to-voltage converter circuit imparts a higher gain to the first amplifier when pumping current flowing in the oxygen-pumping element is in a high frequency range.