| 摘要 |
<p>PROBLEM TO BE SOLVED: To easily set different circular detecting areas even if the place or condition of detection is varied by forming a small circular diameter transmitting opening part by the connection by combination of each curved edge of a shield plate arranged on the periphery of the transmitting opening part. SOLUTION: The Y and Z axial intersections crossing a vertical line X-axis at 60 deg. are taken as the center point of transmitting openings R1, R2 of maximum circle and minimum circle, and each shield plate 6 is rotatably fixed in three pivotal parts 6a in the crossing position with the circumferenceαon each axis. A regulating bar 7 is inserted and set into each guide hole 6b situated in the crossing position of the extension line of each pivotal part 6a with the circumferenceβ, and a shield plate 8 and a regulating bar 9 are provided in the same manner. The regulating bars 7, 9 are moved to rotate each shield plate 6, 8, and each curved edge 6c, 8c contact the periphery of the transmitting opening R1 is moved so as to make contact with the periphery of the transmitting opening R2. Since the shield plates 6, 8 are shifted in phase by 60 deg., the small circular diameter transmitting opening R2 can be formed by the connection by combination of each curved edge.</p> |
