| 摘要 |
PURPOSE:To enlarge the variation width of a delay time, by providing receiving electrodes at different intervals on the right and left of a transmitting electrode, and providing signals which are out of phase, to right and left electrodes in the transmitting electrode. CONSTITUTION:When phase of a signal which is applied to the first electrode 2 of a transducer 21 in the center through a phase shifter 24 is led by 90 deg. than the second electrode 3, a surface wave is generated from the transducer 21 to a transducer 23. Accordingly, a delay time in this case is proportional to a distance between the transducer 21 and the transducer 23. When a signal lagged by 90 deg. is applied, the delay time is proportional to a distance between the transducer 21 and a transducer 22. When a phase difference is 90 deg.--90 deg., outputs of the transducer 22 and the transducer 23 are synthesized, and an intermediate value is taken as a delay time, too. |
