| 摘要 |
PURPOSE:To decrease delay quantity and to obtain the receiving signal of satisfactory quality by setting the delay quantity to match a phase in one wavelength as the delay quantity of continuous wave reception with a duplex probe. CONSTITUTION:When a continuous wave is received, each ultrasonic reception delay quantity in a second probe 1-1, which cause the same wave surface of an ultrasonic wave to be coincident, is defined as Xi, a propagating time for one wavelength of the ultrasonic wave is defined as (tau) and a positive integer number to include '0' is defined as (k). Then, a delay quantity setting part 4 is provided to set continuous wave reception delay Yi, with which the condition of 0<=Yi<tau can be obtained out of Yi=Xi-k.tau, respectively to delay circuits (3-1 to 3-n). Since the condition of lambda=C/f (C is sonic velocity and (f) is an ultrasonic frequency) is obtained for one wavelength lambda of the ultrasonic wave, in case of f=2.5MHz and C=1500m/S, lambda=0.6mm is realized and accordingly, tau=400n S can be obtained. Then, the continuous wave reception delay quantity Yi goes to be 400n S at a maximum. Thus, in comparison with the delay quantity Xi which is needed for coincidence of the same wave surface, the delay quantity goes to be widely small and the receiving degradation of the receiving signal due to the characteristic of the delay circuit can be improved. |
