| 摘要 |
PURPOSE:To eliminate the generation of a noise at the time of switching of a reception delay circuit and to improve the S/N of an image by providing a filter in front of a changeover switch of the reception delay circuit so as to correspond to plural reception delay circuits. CONSTITUTION:When a switching signal S1 is inputted to a switch 3C from a controller 5, the switch 3C selects reception delay circuits (RDL) 3B1, 3B2 thereby. As a result, a signal from a living body received by an ultrasonic probe 1 and sent to a pre-amplifier 3A is inputted to echo filters 4A1, 4A2, respectively, while generating a reception focus point by a delay pattern which the RDLs 3B1, 3B2 have, respectively. Subsequently, a frequency component of only a band required for a tomography image is extracted by them. That is, an unnecessary frequency component inputted from the RDL 3B1 and the RDL 3B2 is eliminated therein, and an output of unnecessary RDL 3B1 and RDL 3B2 contained in an echo signal becomes nearly zero. Accordingly, a switching noise caused by a phase difference comes to be scarcely generated. |
