JPS5844372A - Ultrasonic image pickup system - Google Patents

Abstract

PURPOSE:To improve the sound pressure of a transmitted acoustic wave and to improve OS/N by a method wherein a signal of a time corresponding to a time for propagation from an assumed sound source to a wave-receiving element is arranged on a plane and reception signals are added sequentially on a two- dimensional plane. CONSTITUTION:An assumed sound source is formed at a point Q. Reflected waves from an object are received by a group 4 of wave-receiving elements. A signal Rn among these reception signals is digitized by an A/D converter 5 and stored in a primary memory 6. Coordinate data delivered from a control unit 1 are converted into separate coordinate signals by a subtractor 7. By combining these signals and reading a reference table 8, time data corresponding to the arrangement thereof are delivered therefrom. These data are added to separate values obtained from the control unit 1 and thereby a time is obtained. By controlling the primary memory 6 by the value of this time, a value at the time of a signal received by an n-th element is obtained. This value is arranged additively at a point on a regenerative screen 11 by using an adder 10. All transmission waves are processed repeatedly in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relates to improvements in ultrasound imaging methods. 3. That is, as shown in FIG. It is also possible to simultaneously receive reflected signals by using a plurality of element groups α configured as shown.

The purpose of this invention is to improve the sound pressure of the transmitted sound waves in an image reproducing apparatus that sequentially performs the following steps, and to realize an imaging method with a good signal-to-noise ratio.

As shown in FIG. 2, the present invention uses a plurality of elements T, ~TM when transmitting sound waves. As shown in the figure, such a wave transmitting element is connected to a delay circuit having different delay times.
By performing phasing drive using DM, a sound wave converging at a point Q located at a distance d in front of the element array surface is sent out. The wavefront of the sound wave radiated like this is equivalent to the wavefront when a virtual micro-diameter sound source is placed at point Q, and when a cylindrical wavefront is sent out from each element, the wavefront of M centered at point Q is
A cylindrical wavefront with twice the sound pressure is formed.

The reflected signals obtained by performing such wave transmission are added and arranged on the image reproduction surface (x, y) as shown in FIG.

Here, the value A(xotyo) to be placed is A(xosy
o)=Rn(t, +t, +td) ・・・−・−Q)
It is. However, Rn(t) is the received signal of the corresponding received purple sweet potato,
11.1. is the propagation time of each sound wave, and td is the time from the drive time until the sound wave arrives at point Q. Next, the reference table for making this arrangement is as shown in Figure 4, from the origin to Prepare T(x, y) as the sound wave propagation time. Here, T(x,
y) is given by T(x, y) ”〆x+y /C.The values of t and 2, which are required when arranging equation (1), are based on the positional relationship shown in Figure 3. As shown in FIG. 4, t1=T(IXo−X
dI , lyo '-yd l )t2 ''T (l
xO-Xnl #l)'o-)'-11) It can be obtained by referring to the table.

Here, create the reference table by ΔX1y in the x direction.
It is created by dividing the direction by Δγ, and the receiving element position and the virtual sound source position are respectively divided into xd= and Δx,
By setting xn=LΔxlyd= to be an integer multiple of 'Δysyn'Li'Δy, the capacity of the reference table is reduced.Also, as shown in FIG. Next, an embodiment of the configuration of the signal arrangement according to the present invention will be described in detail with reference to Fig. 6.Here, l is a control unit, which sends out each coordinate data and a wave transmission control signal 1afe. Further, 2 is a wave transmitting element control unit, a part of which is shown in Figure M2, which delays and drives a plurality of wave transmitting element groups 3 to form a virtual sound source shown in Figure 6Q. A plurality of signals R in this received signal group are converted into A/D converters (nft) and converted into numerical values by a converter 5Vc, and each of them is expressed as -order. The memory unit 6Vc stores the information.

On the other hand, the subtracter 7 converts the coordinate data sent from the control unit lVc into four types of coordinate signals.

Combining these four types of signals, reference table 8 (T(
x, y)), time data 11, 1 . is output. td obtained from this jlsji2 and control unit 1
By performing an addition operation on the values of , by the adder 9, the necessary time is given.

Next, this value is used as primary memory! [r By controlling, the values at times j, +t, +td of the signal received by the n-th element are obtained as the output of the -th storage unit 6. This value is added to a point (Xo*yo) on the image reproduction surface ll using the 1jth -adder 10.

Imaging is completed by repeating such processing and arranging all received signals for all transmitted waves on the full image reproduction surface 11.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an element arrangement flj according to a conventional method, and FIG. 2 is a configuration diagram showing an embodiment of a sound source in the present invention.
FIG. 3 is an explanatory diagram showing the positional relationship of the image reproduction surface, FIG. 4 is an explanatory diagram showing the contents of the reference table and the reference method, FIG. 5 is a configuration diagram showing another embodiment of the sound source in the present invention, and FIG. FIG. 6 is a block diagram showing an embodiment of signal arrangement according to the present invention. DESCRIPTION OF SYMBOLS 1... Control part, 2... Wave transmitting element control part, 3... Wave transmitting element group, 4... Wave receiving element group, 5... A/D converter, 6... - Next storage section, 7... Subtractor, 8... Reference table, (5) 9, IO... Adder, 11... Image reproduction surface. (6) Mi Recruitment Uni〇〇・0000・00 f/, RJ-Ichishaku, O 3 Dano 2 Zusai-tei Zunagi-χshi

Claims (1)

[Claims] A virtual sound source is formed outside the plane of the electroacoustic transducer array, and a received signal at a time corresponding to the sound wave propagation time from the virtual sound source to the electroacoustic transducer for wave reception is arranged on a plane to transmit and receive multiple waves. An ultrasonic imaging method characterized by sequentially adding received signals on a two-dimensional plane.