Ultrasonic imaging apparatus operating according to the impulse-echo technique

In ultrasonic imaging apparatus operating according to the impulse-echo method, and including an ultrasonic applicator for causing ultrasonic beam energy to effect ultrasonic scanning of a body region along successive scanning lines, an image registering device with a line generator for controlling the imaging of echo impulses along an image line and with an image generator for controlling image line displacement of successive image lines to form an image during displacement of the ultrasonic beam energy for scanning along successive scanning lines of the body region, said ultrasonic applicator comprising a parabolic reflector and ultrasonic transducer means operable for the transducing of ultrasonic beam energy relative to the successive scanning lines via successive points along border zones and along an intervening central zone of the parabolic reflector during rotation of the transducer means about the focal line of said reflector, and angle responsive signal generator means responsive to the angular movement of the ultrasonic transducer means and operable for controlling the image generator to produce image line displacement at a more rapid rate during transducing of ultrasonic beam energy via points at the border zones of the reflector and at a relatively slower rate during transducing of ultrasonic beam energy via points in the central zone of the reflector, wherein the improvement comprises said angle responsive signal generator means including rotary mark carrier means having a succession of angularly offset marks, and rotatable in synchronism with the rotation of the ultrasonic transducer means, and mark scanner means operably associated with the marks of said mark carrier means for generating mark signals in response to the scanning of the successive marks during rotation of said mark carrier means, the marks of said rotary mark carrier means having a variable spacing such that the mark scanner means scans a relatively rapid succession of marks during transducing of the ultrasonic transducer means via points in the border zones of the reflector and scans a relatively less rapid succession of marks during transducing via points in the central zone of the reflector, and said mark scanner means being operatively connected to said image generator for controlling the rate of image line displacement in accordance with the rate of scanning of said marks by said mark scanner means.