| 摘要 |
PURPOSE:To reduce a difference in the ability to detect water leak by providing a decision part which decides leakage of water from the time integral value of a water leak signal and a decision part which makes a decision from the ratio of a time integral value based upon a dark noise signal when there is no leakage of water. CONSTITUTION:A sensor 1, a waveform shaping circuit 2, a signal continuance integration circuit 3, a water leak decision circuit 5, etc., are provided. Then, oscillation caused by a water leaking sound, noise, etc., detected by the sensor 1 is converted into an electric signal, which is inputted to the circuit 2. The circuit 2 amplifies the electric signal from the sensor 1 and performs waveform shaping so that a signal significant as a water leak signal has a high level and an insignificant signal has a low level. The circuit 3 integrates the time when the input signal has the high level and outputs a time integral value T. Further, the circuit 5 stores the time integral value when there is no water leakage and outputs a decision signal indicating a leakage of water only when the ratio of the integral value T to the time integral value or the integral value T is larger than a set decision reference value. |
