| 摘要 |
PURPOSE:To display a picture with a wide dynamic range from a close part to a distant part by reducing an obvious side lobe in the close part of a probe and decreasing side lobe artifact. CONSTITUTION:The transmission pulse of an n-channel generated in a pulse generation circuit 1 is inputted to a transmission beam former 2. The transmission beam former 2 executes phase delay processing to the transmission pulse of each channel according to the control of a system controller 3 and forms transmission beam. The system controller 3 controls an opening variable circuit 7 and controls the opening width of the probe so that D/A can be kept definite. However, the number of opening elements from the closest part of a probe 5 up to the depth of 40mm is fixed to the definite 26 channels and the opening width of the probe is enlarged so that the D/A can be kept constant when the depth exceeds the 40mm and is further deepened. Thus, a side lobe level L is fixed in a part where depth D is smaller than 40mm. Then, the picture, for which the side lobe artifact is reduced, can be obtained. |
