Abstract: A control circuit for an air cleaner including a gas sensor, an ultraviolet sensor and a control circuit for performing an automatic operation of the air cleaner in response to the detection of outputs of the sensors. A predetermined number of electrical pulses from the ultraviolet sensor are observed by the control circuit during a first predetermined time period after the passage of a second predetermined time period from a point of time when an initial pulse from the ultraviolet sensor has been inputted to the control circuit, the control circuit identifies the predetermined number of the pulses as a drive signal for initiating the operation of the air cleaner.

Abstract: An air cleaning machine to be used in houses, offices and so on utilizes an ultraviolet-ray sensor and a gas sensor jointly to combine the characteristics, so that the operation of the appliance becomes extremely smooth. The appliance operates almost immediately especially when a signal from a light is received. If a cigarette is lighted, for example, indoors, the air cleaning machine operates immediately to clean the air, so that the user may actually feel it. When the gas occurs even under the circumstance where the ultraviolet ray does not reach the light sensor, the normal operation is performed, thus allowing the automatic operation to be effected. Accordingly, clean air is normally provided under the optimum circumstance.