Bandwidth sampling technique for digital focusing in array imaging systems
First Claim
1. An ultrasonic imaging system which focuses ultrasonic signals reflected from an object on at least one focal point according to a receiving focusing method, the system comprising:
- a plurality of transducer elements for respectively receiving said ultrasonic signals relating to said at least one focal point and generating analog signals corresponding to said ultrasonic signals, said analog signals having a frequency band;
a plurality of frequency band transformers, coupled to each of said transducer elements, for respectively receiving and transforming the frequency band of said analog signals received from said transducer elements, each of said frequency band transformers comprising a multiplier and a low pass filter;
each of said transducer elements being coupled to at least two said frequency band transformers;
a plurality of delayed-time difference eliminators, coupled to said frequency band transformers, for eliminating the difference of delay times due to varying positions of focal points and for performing analog to digital conversion, said delayed-time difference eliminators comprising a sampling clock for generating a higher frequency than the frequency bandwidth of an analog signal transformed by a frequency band transformer to which the sampling clock is coupled;
each of said delayed-time difference eliminators comprising a first A/D converter and a second A/D converter;
each of said A/D converters being coupled to a frequency band transformer;
a plurality of memories, connected to said delayed-time difference eliminators for storing digital signals output from said delayed-time difference eliminators;
a plurality of phase compensators, connected to said plurality of memories, for compensating phase errors in digital signals output from said memories and included in a first digital signal and a second digital signal, said first digital signal being generated by said first A/D converter and said second digital signal being generated by said second A/D converter, said phase compensators containing a plurality of multipliers, to carry out quadrature sampling phase-error-elimination;
a plurality of adders coupled to said plurality of phase compensators for adding output signals of said phase compensators; and
an envelope detector for detecting envelope data from output signals of said plurality of adders.
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Abstract
The present invention-relates to an ultrasonic array imaging system for focusing ultrasonic signals which are reflected from an object to be imaged and received by an array transducer. A digital focusing method and system in accordance with the present invention compensates for phase errors which are contained in digital data by using a quadrature sampling method in digital-processing and focusing of ultrasonic signals. Each of a plurality of delayed-time eliminators receive signals generated by quadrature sampling and removes delayed-time differences from signals. Each of phase compensators receives a digital signal in which a delayed-time difference is removed, and compensates the received digital signal for phase errors. An envelope detector is used to detect an envelope signal using the phase error compensated date.
29 Citations
8 Claims
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1. An ultrasonic imaging system which focuses ultrasonic signals reflected from an object on at least one focal point according to a receiving focusing method, the system comprising:
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a plurality of transducer elements for respectively receiving said ultrasonic signals relating to said at least one focal point and generating analog signals corresponding to said ultrasonic signals, said analog signals having a frequency band; a plurality of frequency band transformers, coupled to each of said transducer elements, for respectively receiving and transforming the frequency band of said analog signals received from said transducer elements, each of said frequency band transformers comprising a multiplier and a low pass filter;
each of said transducer elements being coupled to at least two said frequency band transformers;a plurality of delayed-time difference eliminators, coupled to said frequency band transformers, for eliminating the difference of delay times due to varying positions of focal points and for performing analog to digital conversion, said delayed-time difference eliminators comprising a sampling clock for generating a higher frequency than the frequency bandwidth of an analog signal transformed by a frequency band transformer to which the sampling clock is coupled;
each of said delayed-time difference eliminators comprising a first A/D converter and a second A/D converter;
each of said A/D converters being coupled to a frequency band transformer;a plurality of memories, connected to said delayed-time difference eliminators for storing digital signals output from said delayed-time difference eliminators; a plurality of phase compensators, connected to said plurality of memories, for compensating phase errors in digital signals output from said memories and included in a first digital signal and a second digital signal, said first digital signal being generated by said first A/D converter and said second digital signal being generated by said second A/D converter, said phase compensators containing a plurality of multipliers, to carry out quadrature sampling phase-error-elimination; a plurality of adders coupled to said plurality of phase compensators for adding output signals of said phase compensators; and an envelope detector for detecting envelope data from output signals of said plurality of adders. - View Dependent Claims (2, 3, 4)
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5. A method of ultrasonic imaging which focuses ultrasonic signals reflected from an object on at least one focal point and which eliminates phase errors, comprising the steps of:
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reviewing ultrasonic signals reflected from an object on at least one focal point; generating analog signals corresponding to said ultrasonic signals; lowering the frequency bands of said analog signals; eliminating the difference in delay times due to varying positions of focal points by converting said analog signals to digital signals using a sampling frequency supplied form a clock generator; phase compensating the digital signals after the difference in delay times have been eliminated, by using a quadrature sampling technique; adding the digital signals after phase compensation; and detecting envelope data of said digital signals. - View Dependent Claims (6, 7, 8)
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Specification