| 摘要 |
PURPOSE:To make it difficult to be affacted by a reflective object and an environment by installing a light emitting device and a photodetector near an opening part on the outside of a building so that they face a light shielding plate and using the space from a point a certain length higher than the ground to the upper end of the opening part as a detection area. CONSTITUTION:The light emitted from a light source 22 is condensed sectorially by a cylindrical lens 24 and is radiated to the outside through a window 26. If the reflective object enters the detection area indicated by an oblique line, a part of the reflected light is made incident to a sensor through the window 27 and is condensed by a cylindrical lens and is detected by a photodetector 23. The size of the detection area is set optionally in accordance with dimensions of windows 26 and 27. That is, it is possible to cope with an object in the early stage because the object is detected when it approaches the opening part, and precautions are taken against trespass in the state where the opening is opened, and the reliability is high, and the malfunction due to indoor persons is not generated. |
