| 摘要 |
<p>PURPOSE:To detect accurately only a specified moving object without causing a malfunction by detecting that signals from a plurality of sensors have a prescribed time difference between them. CONSTITUTION:Outputs of infrared sensors 2a and 2b are digitized to be signals S1 and S2 by A/D converters 4a and 4b. The signals S1 and S2 are turned to be signals only in a prescribed frequency band by digital filters DF1 and DF2. Next, a cross-correlation determining means CCP computes a cross- correlation value of the signals passing through the filters DF1 and DF2 by using a prescribed cross-correlation formula and determines whether or not the cross-correlation value has a peak of a value being a prescribed value Lth or above found between the upper limit Tmax and the lower limit Tmin of a time difference Tr. When the cross-correlation value has the peak being the prescribed value Lth or above found between the upper limit Tmax and the lower limit Tmin of the time difference Tr, a detection signal is transmitted to an output timer TMR and a detection output is delivered for a prescribed time. According to this method, only a specified moving body can be detected accurately.</p> |
