| 摘要 |
PURPOSE:To enable cleaning of a sensor element at an appropriate heating temperature irrespective of an atmospheric temperature, by a method wherein, through prohibition of a temperature compensation of a connection point between a humidity sensor element and a temperature compensating element, the heating temperature of the humidity sensor element is detected from a potential at the connection point. CONSTITUTION:In case a cleaning takes place over the detection of temperature of a humidity sensor element 2 through measurement of a potential VS at a connection point J between the humidity sensor element 2 and a temperature compensating element 3, the prohibition of a temperature compensating motion by the element 3 is conducted in parallel to the element 3 through connection of a fixed resistor 5 having a sufficiently lower resistance value as compared with the element 3. A connection of a resistor 5 to the element 3 is conducted such that at a cleaning time, a terminal 8 of a driver circuit 7 controlling a switching of a transistor 6 is set to a theoretical level H, a transistor 10 is turned ON through an inverter 9, and a high level potential is applied to the base of the transistor 6 to bring the transistor 6 into ON. This enables the temperature of the element 2 heated by a heater 4 to be held at an appropriate temperature irrespective of the atmospheric temperature of the element 3, and prevents the deterioration and the damage of the element 2 due to an insufficient cleaning or an excessive heat. |
