| 摘要 |
PURPOSE:To obtain an ultrasonic wave array transducer immune to noise by using one as an ultrasonic wave reception and using the other as a dummy whose surface is covered so as not to receive the ultrasonic wave and receiving output signals of array transducers corresponding to them respectively differentially. CONSTITUTION:A dummy transducer 16 mounted in a way of receiving no ultrasonic wave is provided in addition to an array transducer 15 mounted and a bias is applied from a DC bias power supply 17 in common to the corresponding transducers arranged both sides the border between an upper half 15 and a lower half 16 and the output is inputted to a differential amplifier 18. Then outputs 1, 2,... of channels 1, 2,... of the ultrasonic wave array transducers obtained in this way are subjected to elimination of common mode noise and the S/N is improved. Then the electromagnetic noise or noise leaked from a power supply section 17 is eliminated and the sensitivity is improved. |
