JPS6027478B2 - acoustic transducer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to acoustic transducers, particularly acoustic transducers with narrow directional characteristics.

The transducers commonly used in these acoustic transducers are planar or concave transducers.

In the case of a planar transducer, due to the diffraction effect of its closure, the beam of sound waves transmitted and/or selectively received by the transducer expands as the distance from the transducer increases. When a concave transducer is used, the beam of sound waves to be transmitted and/or selectively received is generated at a distance determined by the radius of curvature of the surface, and at the focal point the beam can be made narrower, but it is possible to make the beam narrower. The sound wave beam diverges in front and behind. For this reason, it is generally difficult to obtain a narrow beam within a predetermined distance range from the vibrator. To solve this problem, there is also a lensed vibrator that has a circular plane vibrator with an acoustic lens that is symmetrical about the center of the plane and whose thickness increases from the center toward the periphery. It has been reported that it is effective in narrowing the beam of sound waves. However, when a lens or the like is attached to the transducer, repeated reflections occur at the interface between the transducer and the bonded object, the bonded object and the object, or the sound wave propagation medium during the transmission and reception of sound waves, resulting in the generation of noise. .
For example, in the case of a sound imaging method in which information about an object is displayed by receiving reflected waves from the object, it is conceivable that the direct distance resolution decreases and the signal-to-noise ratio of the image decreases. The present invention has been devised in view of these difficulties and drawbacks.

That is, an object of the present invention is to provide an acoustic transducer that transmits and/or receives acoustic waves and has a narrow directivity characteristic of the acoustic waves within a predetermined distance range from the acoustic transducer. To achieve this objective, the acoustic transducer of the present invention has a plurality of transducers arranged such that the transmitting or receiving surfaces of each transducer have a finite angle with respect to each other, so that the sound waves from the individual transducers are The structure is such that the sound waves are transmitted so as to overlap on a certain tree, or the sound waves are received by individual vibrators that overlap on a certain track. The present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a diagram explaining the principle of the acoustic transducer of the present invention. In the figure, 1, 2, 3, and 4 indicate wavefronts, and these wavefronts are symmetrical with respect to the Z axis, which is the measurement direction. It is assumed that these wavefronts 1, 2, 3, and 4 move along a direction perpendicular to their centers. Along with this movement,
These wavefronts sequentially overlap within a certain range on the Z axis.
That is, the overlapping point of these four wavefronts moves within a certain range on the Z-axis. The acoustic energy at this overlap point is extremely high compared to other points. Therefore, the same effect as when transmitting a narrow acoustic beam with good directivity along this axis can be obtained. Furthermore, upon reception, by receiving these wavefronts 1, 2, 3, and 4, the detection is given a higher weight than the acoustic information at other points other than the Z axis. Although the basic principle has been explained using four wavefronts as representatives, the present invention can be carried out using two or more wavefronts. An acoustic transducer from which the four wavefronts of FIG. 1 are obtained is shown in FIG. This acoustic transducer has four vibrators 5, 6, 7, and 8 arranged symmetrically with respect to the Z axis in FIG. Therefore, these transducers 5, 6, 7, and 8 are arranged such that their respective transmitting or receiving surfaces form a finite angle with respect to each other. 9, 10, in the figure
11 and 12 are surface electrodes, 13, 14, 15, and 16 are back surface electrodes, and between these electrodes are tortoise-strain material layers 17, 18, 19, 2.
0 is placed. The front electrodes 9, 10, 11, 12 are connected to the back electrodes 13, 14, 15, 1 by wires 21.
6 are electrically coupled by wire-22. 2
3 is a wire 1 for connecting an electrode to a controller (not shown) and electrically coupling the vibrators on a plurality of surfaces under the same conditions.

Therefore, during transmission, a pulsed high frequency signal is supplied to the electrodes by this wire 23, and each vibrator 5, 6, 7
, 8 emit sound waves. Further, during reception, this wire 23 supplies the high frequency signal generated by the electrostrictive material layers 17, 18, 19, 201 to the controller. In the first embodiment shown in FIG. 2, each vibrator 5, 6, 7, and 8 was independent, but in the embodiment shown in FIG. We are united.

Therefore, the wires 21 and 22 shown in the first embodiment become unnecessary. Next, FIGS. 4 and 5 show an acoustic transducer of the present invention having a gain distribution.

That is, the third embodiment shown in FIG. 4 shows an example in which the thickness of the tortoise-strain material layers 17, 18, 19, and 20 increases as the distance from the Z-axis increases to produce a gain distribution, and FIG. An example is shown in which a packing layer made of a material such as rubber 30, 31, 32, and 33 whose thickness increases as it moves away from the Z-axis is fixed to the back electrode. FIG. 6 shows an acoustic transducer in which a sound wave reflecting surface 34 is combined with the acoustic transducer shown in FIG.

By combining the sound wave reflecting surfaces 34 in this way, it is possible to further improve the directional characteristics of the sound waves transmitted and/or selectively received within a predetermined distance range, and at the same time, it is possible to further improve the directional characteristics of the sound waves that are transmitted within a predetermined distance range and/or selectively received. This makes it possible to downsize the probe part of the device and adjust the test distance range, increasing the degree of freedom in designing the device and making it easier to manufacture a probe with good performance. In the above explanation, the transmitting and receiving surfaces of the vibrator are considered to be flat, and therefore the waves from the vibrator are considered to be plane waves. However, in order to increase the weight point on the Z-axis in the Z-axis direction, the transmitting and receiving surfaces are It is desirable to have a curved surface.

Similarly, the acoustic reflecting surface 34 may be curved. FIG. 7 shows a block diagram of an ultrasonic imaging apparatus to which the acoustic transducer of the present invention is applied.

In the figure, reference numeral 40 denotes an oscillator, and this output signal is used by a pulse generation circuit 41 to generate a pulse wave electric signal to be applied to a vibrator 42. The reflected sound waves from the subject are received at 42 and STC (SensitMtyTimeContml)
The wave is detected by a detector 44 through a circuit 43 and then sent to a multiplier 45.
An input signal of is created. The signal that came during the increase is scanned.
The signal is sent to the converter 46. scan coverter 4
6 is a transducer group 4 that simultaneously detects the position, angle, etc. of the vibrator.
Receive signal from 9. The video signal from the scan converter 46 is sent to a display section 47 and a recorder 48, where a sound wave image is displayed and recorded, respectively. As described above, according to the present invention, with a simple configuration, a thin acoustic beam with good directivity is created along the Z-axis, which is the measurement direction, and the so-called azimuth resolution in a plane perpendicular to the Z-axis is improved, and the apparent resolution in the Z-axis direction is improved. The depth of focus on the top becomes deeper.

[Brief explanation of drawings]

FIG. 1 is a diagram for briefly explaining the principle of the acoustic transducer of the present invention, FIGS. 2 and 3 are diagrams showing the first and second embodiments of the present invention, respectively, and FIGS. The figures are diagrams explaining the third and fourth embodiments of the acoustic transducer of the present invention each having a gain distribution, and FIG. 6 is a diagram explaining the sixth embodiment of the acoustic transducer of the present invention having an acoustic reflector. , FIG. 7 is a block diagram of an ultrasound imaging device to which the acoustic transducer of the present invention is applied. In the figure, 5, 6, 7, 8 are vibrators, 9, 10, I1, 12
are front electrodes, 13, 14, 16, 16 are back electrodes, 17
, 18, 19, and 2 are electrostrictive material layers, and 21, 22, and 23 are lead wires. Younger brother I diagram Younger brother Z diagram 3rd figure 4th picture Younger brother 6 figure 5 Younger brother Wa diagram

Claims (1)

[Claims] 1. An acoustic transducer characterized by having a plurality of plane vibrators arranged symmetrically in a pyramid shape with respect to the Z-axis direction, which is the measurement direction, and electrically coupled under the same conditions.