Ultrasonic imaging apparatus for displaying B-mode and Doppler-mode images

Claim 1

An ultrasonic imaging apparatus comprising: an ultrasonic transducer, said transducer transmitting and receiving a high-frequency ultrasonic wave suitable for obtaining a B-mode image and a low-frequency ultrasonic wave suitable for obtaining a Doppler-mode image, said transducer outputting a high-frequency echo signal corresponding to the high-frequency ultrasonic wave and a low-frequency echo signal corresponding to the low-frequency ultrasonic wave; transmitting means for driving said ultrasonic transducer to output the high-frequency ultrasonic wave and the low-frequency ultrasonic wave therefrom; receiving means for processing the high-frequency echo signal and the low-frequency echo signal and for outputting a B-mode image signal and a Doppler-mode image signal; and display means for displaying the B-mode image signal and the Doppler-mode image signal output from said receiving means as the B-mode and Doppler-mode images, said ultrasonic transducer including a first piezo-electric ceramic having a center frequency 2f0 that is twice resonance frequency and a thickness corresponding to about 1/2 of the wavelength at the frequency 2f0, a pair of electrodes formed on the front and rear surfaces of said first piezo-electric ceramic, a second piezo-electric ceramic formed on said electrode provided on said rear surface of said first piezo-electric ceramic and having the same thickness as that of said first piezo-electric ceramic, said first and second piezo-electric ceramics having only said pair of electrodes as their output leads an acoustic matching layer formed on said electrode formed on said front surface of said first piezo-electric ceramic and having a thickness corresponding to 1/4 of a wavelength at the frequency 2f0, and said first and second piezo-electric ceramics serving as a transducer having resonance frequency 2f0 to output the high-frequency ultrasonic wave and said acoustic matching layer serving as a transducer having resonance frequency f0 to output the low frequency ultrasonic wave.