Ultrasonic diagnostic apparatus and method for processing ultrasonic signal

An ultrasonic diagnostic apparatus, comprising:

• a transducer composed of plural elements that send an ultrasonic wave to an object to be inspected and receive the ultrasonic wave reflected from the object to be inspected;
• an analog to digital converter that digitizes each of plural received signals received by the plural elements;
• a first mixer that multiplies a signal output from the analog to digital converter and a first digital reference signal;
• a first filter that extracts a signal having a predetermined center frequency from a signal output from the first mixer;
• a digital delay unit that delays a signal output from the first filter;
• an adder that that adds plural signals output from the digital delay units;
• and
• plural signal processing circuits connected to the output terminal of the adder in parallel, wherein:
• each signal processing circuit comprises:
• a second mixer that multiplies a signal output from the adder and a second digital reference signal;
• a second filter that extracts a signal having a predetermined center frequency from a signal output from the second mixer;
• an envelope detector that detects a signal output from the second filter;
• and
• a scan converter that converts a signal output from the envelope detector to a picture signal;
• and
• in each signal processing circuit, the second filter extracts a signal having a predetermined center frequency different every signal processing circuit from the signal output from the second mixer.

An ultrasonic diagnostic apparatus, comprising:

• a transducer composed of plural elements;
• a selecting/driving circuit that selects plural n pieces of elements (n=1, 2, - - - , N) for sending an ultrasonic wave having a center frequency ωs to an object to be inspected and receiving the ultrasonic wave having the center frequency ωs reflected from the object to be inspected;
• analog to digital converters provided corresponding to the plural n pieces of elements (n=1, 2, - - - , N) for digitizing a received signal received by the element;
• first mixers provided corresponding to the analog to digital converters corresponding to the elements for multiplying a signal output from each analog to digital converter and a first digital reference signal having a frequency ωm different from the center frequency ωs;
• first filters provided corresponding to the first mixers corresponding to the elements for extracting a signal having a frequency (ωm−ωs) from a signal output from each first mixer;
• digital delay units provided corresponding to the first filters corresponding to the elements for multiplying a signal output from each first filter and delayed by propagation delay time τn different every element from the sending of the ultrasonic wave to the receiving of it by exp (−jωmτn);
• an adder corresponding to the plural n pieces of elements (n=1, 2, - - - , N) for adding signals output from the digital delay units;
• a second mixer that multiplies a signal output from the adder and a second digital reference signal having a frequency (ωs−ωm);
• an envelope detector that detects a signal output from the second mixer;
• a scan converter that converts a signal output from the envelope detector to a picture signal;
• and
• a display that displays a signal output from the scan converter, wherein:
• a received signal having the center frequency ωs is imaged and displayed.

A method of processing an ultrasonic signal, comprising:

• (1) a process for selecting plural n pieces of elements (n=1, 2, - - - , N) of a transducer composed of plural elements for sending an ultrasonic wave having a center frequency ωs to an object to be inspected and receiving the ultrasonic wave reflected from the object to be inspected and having the center frequency ωs and driving them;
• (2) a process for digitizing plural received signals received by the elements in analog to digital converters provided corresponding to the plural n pieces of elements (n=1, 2, - - - , N);
• (3) a process for multiplying a signal output from each analog to digital converter and a first digital reference signal having a frequency ωm different from the center frequency ωs in the first mixers provided corresponding to the analog to digital converters corresponding to the elements;
• (4) a process for extracting a signal having a frequency (ωm−ωs) from a signal output from each first mixer in first filters provided corresponding to the first mixers corresponding to the elements;
• (5) a process for multiplying a signal acquired by delaying a signal output from each first filter by propagation delay time τn different every element from the sending of the ultrasonic wave to the receiving of it by exp (−jωmτn) in digital delay units provided corresponding to the first filters corresponding to the elements;
• (6) a process for adding signals output from the digital delay units corresponding to the plural n pieces of elements (n=1, 2, - - - , N) in an adder;
• (7) a process for multiplying a signal output from the adder and a second digital reference signal having a frequency (ωs−ωm) in a second mixer;
• (8) a process for detecting a signal output from the second mixer in an envelope detector;
• (9) a process for converting a signal output from the envelope detector to a picture signal in a scan converter;
• and
• (10) a process for displaying a signal output from the scan converter on a display, wherein:
• the received signal having the center frequency ωs is imaged and displayed.