| 摘要 |
PURPOSE:To prevent malfunction by setting ultrasonic wave pulses so that the detection range of a body is wider in installation and adjustment than in normal use. CONSTITUTION:The directivity depends upon the ratio of wavelength lambda to the diameter of a horn 1, so a detection range is varied by slight variation in frequency. This is utilized to set ultrasonic wave pulses so that the detection range 3 in setting adjustment is wider than the detection range 2 in normal use. Consequently, a fixed obstacle in an area close to the detection range 2 in normal use is removed, so malfunction is prevented. |
