JPS5962040A - Ultrasonic probe - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasound probe suitable for an ultrasound imaging device implementing variable focus and variable aperture.

Conventionally, ultrasonic imaging devices have adopted a method of transmitting and receiving waves with a thin ultrasonic beam uniformly from a shallow region to a deep region in order to obtain high-resolution, high-quality images. One way to achieve such a narrow beam is to
A so-called variable focus method is known in which the beam is appropriately narrowed down depending on the depth to change its focus. Conventionally, the focus has been changed by adjusting the delay map imposed on the vibrating element of the probe using such variable rules. Furthermore, the variable aperture technique also uses the entire surface of the aperture, although the aperture is changed. Furthermore, when implementing a variable filter,
Since a transducer with a fixed f-characteristic was used, there was a limit to the range of variation. As long as one continuous, essentially uniform aperture or group of vibrating elements is used, a variable focal point for transmitting waves has not been considered.

In view of these points, an object of the present invention is to provide an ultrasound probe suitable for an ultrasound imaging device that can achieve variable focus and variable aperture at the same time.

The present invention will be described in detail below using the drawings. The present invention
This is an application of a type of annual array in which the arrays are arranged concentrically so as to share one sound ray, but the structure is such that the plate thickness increases toward the outer ring, and the resonant frequency f. The structure of the main parts is shown in a cross-sectional view, with the beam being lowered and electronically or acoustically focused far away. In the figure, in the 14, 12.13 tri annular vibrator, the outer ring has a thicker plate. Reference numeral 2 denotes an acoustic lens bonded to the front surface of the vibrator, and its surface exhibits a concave surface in which parabolic or spherical surfaces are continuously formed such that the radius of curvature becomes smaller at the center. In this case, lens 2,
It is formed of a material whose sound velocity C is higher than the sound velocity C8 of the medium 3, and conversely, in the case of the relationship C<co, it is formed into a convex shape with a completely opposite relationship to the above.

Note that a matching layer may be interposed between the vibrator and the lens 2.

4 is a backing material bonded to the back surface of the vibrator. When the vibrator with such a configuration is energized to transmit and receive ultrasonic waves, the center part transmits and receives the waves at a high frequency f, a short focal point, that is, a mainly shallow part, with a small aperture, and the outer peripheral part transmits and receives ultrasound waves at a lower frequency f3. It functions to send and receive sound waves with a long focal point and a large aperture aimed at deep areas.

FIG. 2 is a diagram showing another embodiment of the probe according to the present invention. The one in Fig. 2 has the transducer itself connected to the lens 2 in Fig. 1.
It is arranged so that it has the same curved surface as the surface of, or a curved surface similar to it, and can exhibit multi-frequency and multi-focal functions as in Fig. 1. Note that in this case as well, there is no problem in bonding the matching layer to the surface of the vibrator.

A case in which ultrasound imaging is performed using such a multi-frequency, multi-focal annual array will be described next. Transmitters and receivers also need to be equipped with a wide variety of functions and receive signals while appropriately switching between them. In this case, the timing of the transmission pulses is made to match for all the transducers, so that even if there is mutual interference, images will not be duplicated.

Further, the low-cut characteristics of the high-frequency range in the center and the high-cut characteristics of the low-frequency range in the outer ring are made strict for both transmission and reception to prevent mutual interference.

Figure 3 shows the main configuration of an example of such a transmitter/receiver. show. In FIG. 3, an individual transmitting/receiving circuit 2 is provided for each transducer of the ultrasonic probe 10 as shown in FIG. 1 or 2.
0.30.40'r provided. Each circuit has the same configuration, and if we focus on one of the circuits 20, it is composed of filters 21 and 7 (nox filters 22.23 and a receiving circuit 24).Band pass filters 22.2
3 has a passband characteristic that matches the frequency band that the inner ring vibrator 11 carries, and the driving pulse from the pulser 21 passes through the filter 22 to the vibrator 1.3. t/71: Guided. On the other hand, the echo signal received by the vibrator 1 is guided to the receiving circuit 24 via the filter 23.

The noise filters in the other transmitting/receiving circuits 30 and 40 are made to match the frequency bands to which the middle ring and outer ring vibrators 12 and 13 correspond, respectively.

The receiving circuit of each channel includes a logarithmic amplifier, a detector, etc., and the output of each receiving circuit is connected to an attenuator or an amplifier 25.
．． 35.45t- to the summing amplifier 50, where they are combined into one video signal and output. Amplifiers 25, 35
．． The gain of 45 is controlled by a controller 60, and is a VC so that so-called time gain control (TGC) can be applied. Fourth
The figure shows the situation, and the outputs of the receiving circuits 24, 34, 44 shown in (a), (b), and (c) are shown in (b), (e).
The signal is processed using the TGC characteristics shown in (f).

In this way, a multi-frequency, multi-focal probe is used to target shallow areas with small apertures and high frequency sound waves, and deeper areas with larger apertures and lower frequency sound waves. By obtaining and processing echo signals, it becomes possible to obtain uniformly high-quality images from shallow to deep areas.

In addition, - To give a specific example, the vibrator at the center is 10φmm.
, f(1;5MHz + focal length'+=30t+
m and its depth range is 0 to 5Qm+, and the intermediate ring is 20φ" + fo==3 MHz, f
2-8 Q my, the depth range is 50 to 1201
m, and the outer ring is 40φ.

fo:=1.8MHz, f5=18QIJ depth range is 120-300#11. At this time, the fractional bandwidth of each vibrator is approximately the same, approximately 50 inches.

The vibrators described above are annular array arranged at a constant pitch in the radial direction, but the method of the present invention is not limited to this, and the method of the present invention can also be applied to a linear array. If appropriate processing is performed at the synthesis stage, the array pitch of the transducers does not have to be constant, and the fractional bandwidth of each ring may be varied by varying the weighting of the backing. Furthermore, the number of rings is not limited to three.

As described above, according to the present invention, it is possible to realize an ultrasonic probe that has multiple frequencies and multiple focal points and can simultaneously realize variable focus and variable aperture.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the main parts of an embodiment of an ultrasound probe according to the present invention, FIG. 2 is a diagram showing another embodiment of the invention, and FIG. 3 is a diagram showing an ultrasound probe according to the present invention. A configuration diagram showing an example of the transceiver used, and FIG. 4 is an operational waveform diagram. 1++ 12.13... Annular vibrator, 2...
・Sound sauce/zu, 3...medium, 4...backing material,
10...Ultrasonic probe, 20.30.40...Transmission/reception circuit, 25,35°45...Amplifier, 50...Summing amplifier, 60...Controller.

Claims (1)

[Claims] 0) Annular transducers arranged in concentric circles so as to share one sound ray, such as an outer ring.The resonant frequency of the transducer is lowered and the ultrasonic beam is transmitted to a distant point. 1. An ultrasonic probe configured to focus on