Ultrasound signal processor, ultrasound signal processing method, and ultrasound diagnostic device

An ultrasound signal processor that selectively drives a plurality of transducer elements arrayed in an ultrasound probe and executes ultrasound transmission and reception to a subject to perform velocity analysis by a color flow mapping method, the ultrasound signal processor comprising:

• a transmitter configured to select a transmission transducer element array from the plurality of transducer elements, and perform transmission of ultrasound from the transmission transducer element array that is focussed within the subject, for a plurality of transmission events included in one of transmission event sets;
• a receiver configured to generate a received signal sequence for a transducer element of a reception transducer element array selected from the plurality of transducer elements, based on reflected ultrasound received by the transducer element of the reception transducer element array, for each of the transmission events;
• a phasing adder configured to generate an acoustic line signal, for each of the transmission events, for a plurality of observation points included in a main target area including an area corresponding to an area in which the ultrasound focuses within the subject and a sub-target area adjacent to the main target area in an array direction, by performing phasing addition to the received signal sequence based on the reflected ultrasound obtained from each of the observation points;
• and
• a velocity calculator configured to generate a complex acoustic line signal by performing quadrature detection to the acoustic line signal for each of the transmission events, and calculate an average velocity, based on time change of a phase of the complex acoustic line signal for each of the observation points, wherein
• the phasing adder performs delay processing for changing a method for calculating a transmission time in which the ultrasound transmitted reaches each of the observation points, depending on, in at least one of the main target area and the sub-target area, whether a depth of each of the observation points is equal to or greater than a focal depth at which the ultrasound focuses within the subject, and
• as one method of calculating the transmission time, the phasing adder adds a first time and a second time when the depth of each of the observation points is equal to or greater than the focal depth at which the ultrasound focuses within the subject, wherein the first time is a time in which the ultrasound transmitted reaches a reference point in an area at which the ultrasound focuses from the transmission transducer element array, and the second time is a time in which the ultrasound transmitted reaches each of the observation points from the reference point, and subtracts the second time from the first time when the depth of each of the observation points is less than the focal depth at which the ultrasound focuses within the subject.