Inventors:
Carl F. Klein - Milwaukee WI
Paul E. Thoma - Burlington WI
John E. Aukofer - Milwaukee WI
Assignee:
Johnson Controls, Inc. - Milwaukee WI
International Classification:
G01N 2762
G11C 1302
Abstract:
An air pollutant and/or fire combustion sensing apparatus includes a charged insulating sensing electrode layer establishing an electric field as the result of electric dipoles and/or electric monopoles in or on the sensing layer. The layer has a high surface and bulk resistivity. The layer has a minimal water absorption at environmental humidities. The electric field of the sensing layer creates electrostatic sensing reactions with the gaseous products of combustion and environmental pollution and produces an amplification of the charge detection characteristic to alter the charge of the electrode. In a capacitive sensor, the sensing layer is mounted within and in spaced relation to a ground shield member. The sensing layer is thereby exposed and produces a sensitive capacitive detector for sensing of a wide spectrum of combustion products and the like. Optimum results are obtained by the charging of dielectric materials such as polytetrafluoroethylene (Teflon TFE), perfluoroalkoxy (Teflon PFA), fluorinated ethylene-propylene (Teflon FEP), polystyrene or polyethylene, which also provide detection as the result of their gaseous adsorption characteristics.
