| 摘要 |
PURPOSE:To enable to obtain thin ultrasonic wave beams with a single probe in a wide sound field area by attaching plural electroacoustic transducing elements with wide band characteristics, a tuning circuit connected to these elements and a switching unit which selects these element freely. CONSTITUTION:Discoidal electroacoustic transducing element 10 and ring-shaped electroacoustic transducing element 12 are arrayed and fixed concentrically. Ultrasonic wave pulse beams are sent to the sound field media from transmitting/ receiving faces 10a and 12a and the reflected echoes are also received from the sound field media. Two matching layers 14 and 16 are sticked to transmitting/ receiving surfaces 10a and 10b and a driving signal is supplied from ultrasonic wave transmitting/receiving circuit 24 to the range between common input terminal 18 and respective element input terminals 20 and 21. A turning circuit consisting of coil 26 is connected to electrodes 10 and 12 and alteration switch 30, which selects elements 10 or 12 freely and connects the selected element to circuit 24, and controller 32 are also attached. Thus, the operation of switch 30 makes it possible to change effective opening area of these electroacoustic transducing elements and obtain ultrasonic wave beams with a thin beam diameter in the wide range. |
