| 摘要 |
PURPOSE:To prevent an output of any erroneous alarm signal, by providing a new gate pulse outside a width of a gate pulse synchronizing laser output light to allow detection of a received signal exceeding a fixed level within the gate pulse width. CONSTITUTION:A new gate pulse E is provided outside a width of a gate pulse synchronizing laser output light to allow detection of a received signal G exceeding a fixed level within the width of the gate pulse E as well. Moreover, in this case, a signal processor 6 is used to determine that a signal detected before or after the signal G or detected within the width of the gate pulse synchronizing the preceding or subsequent emission laser light is not attributed to the reflected or scattered light from an object. Therefore, an output L of an inverter 15 moves to LOW by detecting solar light or reflected light or scattered light thereof or incident light from other light sources within the width of the gate pulse synchronizing the laser output light through reflected or scattered light is not detected from a nearby object. An alarm signal N maintains the state of LOW thereby eliminating the outputting of any erroneous alarm signal N. |
