| 摘要 |
<p>PURPOSE:To reduce the amplification factor of an AGC amplifier, to suppress the amplification of noises and to detect an obstacle stably by inputting received light signals and a lighting signal from a reference light source having the same phase as the received light signals through a mixer. CONSTITUTION:Light from a reference light source 1 and light from an operating light source 2 are projected on an obstacle 3. The distance to the obstacle 3 is operated based on the ratio between the amounts of reflected lights. At this time, the received light signals from a received light amplifier 4 and a lighting signal which is a part of the light from the light source 1 having the same phase as that of the received light signals are mixed in a mixer 7 and inputted into an AGC amplifier 5. Even if the obstacle 3 is not present or located at a position separated by a long distance, the apparent signal from the light source 1 becomes large, and the amplification factor of the amplifier 5 becomes small. Therefore, noises are not amplified largely, and the obstacle can be detected always stably. Thus, the occurrence of erroneous operation can be prevented.</p> |
