JPH0116393B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a switched array scanning type ultrasound imaging apparatus that uses both a linear transducer array and an arcuate transducer array.

2. Description of the Related Art Conventionally, linear array vibrators in which a plurality of piezoelectric vibrators are arranged in a straight line and circular array vibrators in which a plurality of piezoelectric vibrators are arranged in a circular arc are well known. FIG. 1 shows the state of beam scanning by the linear array vibrator 10, in which N piezoelectric vibrators are
Linear scanning is performed on the TD while shifting one set of m transducers (7 in the figure), and at this time, the m transducers in the center are energized more slowly than the outer ones (phase drive). ), the emitted ultrasonic beam is focused as shown in the figure, and a narrow beam B is used to scan at a certain depth.

Further, FIG. 2 shows the state of scanning by the circular arc array vibrator 20, and shows the case where a plurality of piezoelectric vibrators TD are linearly scanned similarly to FIG. 1. The scanning beams with equal angular density are emitted toward the subject 23 in such a manner that they intersect with each other at the lower surface of the housing 21, ie, near the contact surface 22 with the subject. Therefore, the ultrasound beam performs sector scanning within the subject. In this case as well, the transducer TD is phase-driven to make the ultrasonic beam narrow at a certain depth.

Such a linear array transducer 10 is suitable for abdominal observation, while the arcuate array transducer 20 is suitable for chest observation, and it is desirable that it can be used commonly in one ultrasound diagnostic apparatus. However, since the linear array and the circular arc array do not have the same required delay time distribution in the phase drive of the piezoelectric vibrators used, there is an inconvenience that two sets of delay circuits must be installed. In other words, in the case of a linear array, a positive focal length is set so that the wavefront becomes a concave surface at the array, and a concave phase difference distribution is created, that is, the phase difference distribution is delayed toward the center. In some cases, the array itself already has an excessively concave surface, so in order to focus it at an appropriate depth somewhere in the body, it is necessary to use a convex surface, that is, m oscillators driven simultaneously, to reduce this concavity. A similar focused wavefront cannot be obtained unless the center part is energized faster than the outer part. Therefore,
From the viewpoint of the distribution of the required phase difference, the two are in an inverse relationship to each other, and it is unreasonable to share one delay circuit.

In view of these points, the purpose of the present invention is to provide a switched array scanning type ultrasonic probe that can be used in both linear array probes and circular arc array probes with extremely small switching changes in the delay circuit. The present invention aims to provide a sound wave imaging device.

The present invention will be explained in detail below using the drawings. FIG. 3 is a configuration diagram showing an embodiment of the essential parts of the ultrasound imaging apparatus according to the present invention. In Figure 3, 31
is a multiplexer, 32 ₁ to 32 ₇ are bidirectional buffer amplifiers, 33 is a delay map, 34 is a delay line, 35 is a switch, 36 is a pulser,
37 is an amplifier. The multiplexer 31 selects m transducers for linear scanning and connects them to the buffer amplifiers 32 ₁ to 32 ₇ . The delay map 33 is a matrix circuit consisting of the output of the delay line 34 and the inputs of the buffer amplifiers 32 ₁ to 32 ₇ , and is designed to connect arbitrary rows and columns, respectively. In the figure, the cross points marked with circles are connection points. day line 34
It is a delay line that can be propagated in both directions, such as an LC ladder type, and multiple intermediate taps are connected to the delay map 33.
guided by. A pulse from a pulser 36 is applied to this delay line 34 via a switch 35. On the other hand, when a reflected wave is received, the echo signal obtained from the delay line 34 is guided to the amplifier 37 of the receiving circuit via the switch 35.

Note that the buffer amplifiers 32 ₁ to 32 ₇ are not limited to bidirectional ones, and separate buffer amplifiers may be provided for transmission and reception, and these may be used by switching.

In such a configuration, it is assumed that the arrangement pitch of the piezoelectric vibrators of the array vibrators 10 and 20 is substantially the same, and the arc length of the circular arc array and the scanning width of the linear array are equal. In such a case, the following equation holds true regarding the wavefronts generated by these vibrators.

1/f=1/a+1/b (1) Here, f is the distance of the focal point of the synthesis result, that is, the distance from the array to the focal point (radius of curvature of the wavefront). a, b depend on the curvature of each day map and array. Their inherent negative or positive focal length (if negative, the convex wavefront) Here, for example, the pitch of the transducer is 1.5 mm, the total number of transducers is 64, and the range within which the transducer can be moved within the specified transmitting and receiving aperture. Assume that there are 56 pieces. In the circular arc array, the radius r = 50 mm (sector scanning of just over 90 degrees is possible), and the focusing point, f, is set 80 mm ahead of the crossover point Pc, i.e., f = 50+
If you want to set 80=130mm, use f=130 and a in equation (1).
By substituting =50, we get b=-81.25mm. As shown in FIG. 3, by switching the entrance and exit of the suspended delay line using one day map 33, when scanning sectors with the circular arc array 20, -81.25 mm (crossover point Pc
at a distance of 81.25 mm from the other linear array 1
81.25 from the transducer surface when performing linear scanning at 0
Each corresponding electrical focal length can be achieved such that the beam can be focused to a depth of mm. Therefore, the same delay map 33 having the same connection pattern can be used for both the linear array vibrator and the arc array vibrator, and only the delay line 34 needs to be used properly. That is, when connecting the arc array, the switch 35 is connected to the S side so that convex phase drive is performed.
Pulses from the pulser 36 are guided to the delay line 34 (in the direction of the dotted line), and the vibrators in the center are energized faster than those on the outside. On the other hand, when using a linear array vibrator, since it is sufficient to form a concave wavefront, the switch 35 is connected to the L side, and the pulses from the pulser 36 are guided to the terminal on the opposite side of the delay line 34 from the above case. (in the direction of the solid line), the outer vibrators should be energized more quickly than the center.

Note that the transducer arrangement pitches of the linear array transducer and the arc array transducer do not necessarily have to be the same, and may be different pitches. For example, in the above example, if the pitch of the linear array transducer is changed from 1.5 mm to 1.6 mm, the focal point (convergence point) will be located at a depth of 71.41 mm, and 1.7 mm.
mm, the depth will be 63.26mm, and there is no need to change the day map.

The above explained the phase drive when transmitting waves, but the connection is exactly the same when receiving waves.
The only difference is that the direction of signal flow is the opposite of that during transmission.

As explained above, according to the present invention, the same delay circuit system can be shared for both types of scanning by using the focusing delay map in a reverse relationship for linear scanning and sector scanning. It is possible to realize an ultrasonic imaging device that can perform

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the state of scanning by a linear array transducer, FIG. 2 is a diagram for explaining the state of scanning by an arcuate array transducer, and FIG. 3 is a diagram for explaining the state of scanning by an arcuate array transducer. FIG. 2 is a configuration diagram showing an example of a main part. TD...Piezoelectric vibrator, 10...Linear array vibrator, 20...Circular array vibrator, 33...Delay map, 34...Delay line, 35...
Switch, 36...Parsa.

Claims (1)

[Claims] 1. In an ultrasound imaging device that can share a linear array transducer and an arc array transducer, bidirectional propagation of signals is possible between input and output terminals,
A delay line provided between input and output terminals and having a plurality of intermediate taps from which input signals can be taken out with different time delays; a plurality of lines respectively connected to the plurality of intermediate taps of the delay line, and a plurality of lines leading to the selected plurality of transducers of the array transducer to be used. and a delay map connected with each other with a predetermined phase difference relationship, and by simply changing the signal propagation direction of the delay line by switching with the switch without changing the connection state of the delay map, the signal propagation direction of the delay line can be changed. An ultrasonic imaging device characterized in that a time delay for an arc array transducer and a time delay for an arc array transducer can be obtained.