| 摘要 |
PURPOSE:To easily decide a distance to a human body to be detected by utilizing a signal for detecting the number of persons, by scanning circularly a visual field of an infrared ray detecting element, deciding the number of persons based on an output signal of a signal processing part and also, deciding the distance to the human body to be detected. CONSTITUTION:An output of an infrared ray detecting element 2 as a result of having scanned circularly a visual field is amplified by a preamplifying part 3, and thereafter, inputted to a band pass filter in a signal processing part 4, an unstable low-frequency component and an unnecessary high-frequency component are cut, and an S/N is improved. An output of the band pass filter is A/D-converted and outputted to a microcomputer for constituting a deciding part 5. This microcomputer inputs successively an A/D-converted waveform at every one rotation by synchronizing with a rotation of a circular scanning optical system 1, and detects the number of persons and decides a distance to the human body to be detected by using a waveform of a difference obtained by subtracting a reference waveform stored in a storage part 5a from an input waveform. |
