| 摘要 |
PURPOSE:To eliminate the malfunction caused by the movement of air or short- time power failure, by providing an averaging circuit and an input prohibiting circuit between the output of a gas sensor and a control circuit performing automatic operation. CONSTITUTION:The control circuit 30 connected to a power source 29 obtains the signal from an operation circuit 31 to drive an electromotive blower 2; at the time of the setting of automatic operation, the smoke of tobacco is detected by a gas sensor 12 and, when the output value thereof changes by a definite value or more from an operation reference level, the electromotive blower 2 is automatically operated. When a power failure detection circuit 34 is connected to the power source 29 and the output thereof is connected to an input prohibiting circuit 36 and power failure is generated, the control circuit 30 operates so that the output signal of a detection circuit 34 is prohibited from inputting to the averaging circuit 37 of the next stage. For example, the averaging circuit 37 averages values at every 4sec 8 times and the average value is set as the input signal of the control circuit 30 to develop the function of leveling the instability of the output of the gas sensor 12.
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