| 摘要 |
PURPOSE:To obtain a B mode image of excellent image quality regardless of the frequency of an ultrasonic echo signal. CONSTITUTION:A detecting time constant controller 7 detects the change of the passing frequency band of a dynamic filter 3, and sets and alters the detecting time constant of an envelope detector 6 by interlocking with it. That is, when the passing band of the filter 3 is high, a relatively small detecting time constant is set. When the band of the filter 3 is low, a relatively large detecting time constant is set. Accordingly, the envelope can be detected at the optimum detecting time constant from the shallow part to the deep part of the image, and the excellent image quality can be obtained at any depth. |
