Ultrasonic flowmeter

Claim 2

An ultrasonic flowmeter comprising: a transducer made up of an array of elements; means for driving part of said transducer elements in a prescribed interval thereby to repeatedly transmit an ultrasonic wave to a target; a parallel reception beam forming means for rectifying phases of signals from said transducer elements and for producing parallel reception signals derived from reception beams with different directivities; a sampling means for sampling each of said parallel reception signals and for storing said sampled signals; filtering means for performing moving target indication through a differential process across signals having a certain time duration since transmission among the signals from said sampling means; a first one-dimension Fourier transform means for performing Fourier tranformation for the output of said filtering means in the direction of alignment of the reception beams; and a second Fourier transform means for performing Fourier transformation sequentially for the outputs of said first Fourier transform means in the direction of repetitive transmission so that lateral velocity and axial velocity of a moving object in said target are obtained form a two-dimensional distribution of the outputs of said second Fourier transform means.

Claim 3

An ultrasonic flowmeter according to claim 1, wherein said parallel reception beam forming means includes means for forming a plurality of reception beams having different directions simultaneously.

Claim 4

An ultrasonic flowmeter according to claim 1, wherein said parallel reception beam forming means includes means for forming a plurality of reception beams having an equal focal distance and different focal directions simultaneously.

Claim 5

An ultrasonic flowmeter according to claim 1, wherein said parallel reception beam forming means comprises a one-dimension Fourier transform means for performing Fourier transformation for each of said reception signals received by said transducer elements in the direction of alignment of said transducer elements.

Claim 6

An ultrasonic flowmeter according to claim 1 further comprising means for obtaining distribution of velocity vectors on a two-dimensional plane from the outputs of said second Fourier transform means and for displaying the distribution on a two-dimension screen.

Claim 7

An ultrasonic flowmeter comprising: a transducer made up of an array of elements; means for driving part of said transducer elements in a prescribed interval thereby to repeatedly transmit an ultrasonic wave to a target; a parallel reception beam forming means for modifying a phase of signals from said transducer elements and for producing parallel reception signals derived from reception beams with different directivities; a sampling means for sampling each of said parallel reception signals and for storing said sampled signals; filtering means for performing moving target indication through a differential process across signals having a certain time duration since transmission among the signals from said sampling means; a first one-dimension Fourier means for performing Fourier transformation for the output of said filtering means in the direction of alignment of the reception beams; a second Fourier transform means for performing Fourier transformation sequentially for the outputs of said first Fourier transform means in the direction of repetitive transmission; function generation means for generating a prescribed function of space frequency σ in correspondence to all measurable lateral velocities and axial velocities; and two-dimensional correlation means for evaluating a two-dimensional correlation function between the output of said second Fourier transform means and the output of said function generation means; wherein axial velocity and distant velocity are evaluated from the position of a peak value of the output distribution of said two-dimensional correlation means.

Claim 8

An ultrasonic flowmeter comprising: a transducer made up of an array of elements; means for driving part of said transducer elements in a prescribed interval thereby to repeatedly transmit an ultrasonic wave to a target; a parallel reception beam forming means for modifying a phase of signals from said transducer elements and for producing parallel reception signals derived from reception beams with different directivities; a sampling means for sampling each of said parallel reception signals and for storing said sampled signals; filtering means for performing moving target indication through a differential process across signals having a certain time duration since transmission among the signals from said sampling means; a first one-dimension Fourier means for performing Fourier transformation for the output of said filtering means in the direction of alignment of the reception beams; a second Fourier transform means for performing Fourier transformation sequentially for the outputs of said first Fourier transform means in the direction of repetitive transmission; function generation means for generating a prescribed function of space frequency σ in correspondence to all measurable lateral velocities and axial velocities; and two-dimensional correlation means for evaluating a two-dimensional correlation function between the output of said second Fourier transform means and the output of said function generation means; wherein axial velocity and distant velocity are evaluated from the position of a peak value of the output distribution of said two-dimensional correlation means.

Claim 9

An ultrasonic flowmeter comprising: means for repeatedly transmitting an ultrasonic wave to a target; a transducer made up of an array of transducer elements, each of said transducer elements for receiving ultrasonic waves reflected from said target; sampling means for sampling signals from each of said transducer elements; Fourier transformer means for performing Fourier transformation on said sampled signals in the direction of repetitive transmission; means for deriving flow velocity of said target and the direction thereof for enabling analyzing the output of said Fourier transformer means on a multi-dimensional plane having a first axis indicating location of the output of said Fourier transformer means and a second axis indicating location of said transducer elements.

Claim 10

An ultrasonic flowmeter comprising: means for repeatedly transmitting an ultrasonic wave to a target; a transducer made up of an array of transducer elements, each of said transducer elements for receiving ultrasonic waves reflected from said target; sampling means for sampling signals from each of said transducer elements; Fourier transformer means for performing Fourier transformation on said sampled signals in the direction of repetitive transmission; means for deriving flow velocity of said target and the direction thereof for enabling analyzing the output of said Fourier transformer means on a multi-dimensional plane having a first axis indicating location of the output of said Fourier transformer means and a second axis indicating location of said transducer elements.

Claim 11

An ultrasonic flowmeter comprising: means for repetitive transmission of ultrasonic waves; receiving means including a receiving array transducer for receiving reflection waves of the transmitted ultrasonic waves; converting means responsive to the receiving means for converting received signals into phase and amplitude information; multi-dimensional function means responsive to the converting means for converting the received signals with the phase and amplitude information into a multi-dimensional function with parameters related to the specific location and time of each transmission of the ultrasonic waves; and multi-dimensional velocity vector means responsive to the multi-dimensional function means for converting the multi-dimensional function into a multi-dimensional velocity vector.

Claim 12

An ultrasonic flowmeter comprising: means for repetitive transmission of ultrasonic waves; receiving means including a receiving array transducer for receiving reflection waves of the transmitted ultrasonic waves; converting means responsive to the receiving means for converting received signals into phase and amplitude information; multi-dimensional function means responsive to the converting means for converting the received signals with the phase and amplitude information into a multi-dimensional function with parameters related to the specific location and time of each transmission of the ultrasonic waves; and multi-dimensional velocity vector means responsive to the multi-dimensional function means for converting the multi-dimensional function into a multi-dimensional velocity vector.

Claim 13

An ultrasonic flowmeter according to claim 8, wherein the ultrasonic flowmeter is utilized for measuring blood flow and the multi-dimensional velocity vector means provides a multi-dimensional velocity vector of the blood flow to be measured.