JP2016205997A - Ultrasonic transmitter-receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a spatial resolution and reduce an unobservable region to be formed in the vicinity in a three-dimensional measurement device performing sweep irradiation of ultrasonic signals.SOLUTION: A measurement device using ultrasonic signals is configured to: include a transmitter provided with a one-dimensionally-arrayed vibrator divided into many partial apertures; transmit an ultrasonic signal by applying a drive signal for each partial aperture; and involve a receiver which receives a signal obtained by reflecting the transmitted signal on a target object. In the measurement device, an azimuth resolution and observation region restriction can be simultaneously improved with selection of the configuration of the receiver, the configuration of concave convergence and the configuration of the drive signal.SELECTED DRAWING: Figure 12

Description

  The present invention relates to an ultrasonic transmission / reception apparatus with high spatial resolution.

  Various apparatuses that visualize three-dimensional information of space with ultrasound are known. Among them, as an example of the most effective method, signals having different frequencies are applied to an array transducer having inverted polarization axes (see Patent Document 1), and an ultrasonic signal is swept and irradiated from a target object to a three-dimensional space. An underwater imaging device (see Patent Document 2) that collects information in a three-dimensional space by receiving a reflected signal is known.

  However, according to the method of Patent Document 2, the high resolution in the azimuth direction is accompanied by a decrease in the distance resolution, improving both the high resolution in the azimuth direction and the distance resolution at the same time, and realizing a high degree of three-dimensional spatial resolution. It is difficult to do.

  Therefore, as a method for solving this problem, the one-dimensional array transducer is divided into a plurality of partial apertures, and an ultrasonic signal is transmitted by applying a drive signal for each partial aperture. In the configuration to receive the signal reflected by the ultrasonic wave, the ultrasonic wave transmission / reception device that can simultaneously improve the resolution of azimuth and distance by selecting the electrode shape of partial aperture, drive signal waveform, and drive signal intensity distribution (Patent Literature) 3) is also known.

  However, this ultrasonic transmission / reception apparatus has a particularly complicated electrode shape configuration of the transmitter partial aperture, and there is a limit to improving the spatial resolution performance.

  In addition, in order to provide a spatial resolution in a direction orthogonal to the sweep irradiation direction of the ultrasonic signal, the ultrasonic latticed three-dimensional electronic imaging device in which the receiver has a finite aperture and the receiver has a two-dimensional surface shape. As a secondary effect of this configuration, an improvement in spatial resolution is also expected (see Patent Document 4).

  However, according to such a conventional configuration, the effect of improving the directivity by the combined use of the receiver is insufficient, and there is a limit to improving the spatial resolution performance.

  Further, according to the method of Patent Document 2, it is difficult to change the focal length, and by setting the application time of the signal for driving the partial aperture in a concave shape according to the partial aperture position on the one-dimensional array, the focal length is set. There is also a proposal that can be changed electronically (see Patent Document 3), but the edge of the transmitter aperture does not contribute, so the resolution is severely degraded.

  Furthermore, according to the method of Patent Document 2, since finite time is required for signal irradiation in each direction, it takes a long time to complete irradiation in all directions, and this time zone is received due to interference by transmission signals. Becomes difficult, and a wide area where measurement is impossible occurs in a short-distance region.

  From the above situation, it is difficult to simultaneously improve the azimuth and distance resolutions required at the time of short-distance observation and to realize a high degree of three-dimensional spatial resolution.

JP 47-26160 A Japanese Patent Publication No. 51-44773 JP 2010-71967 A JP2013-57518A JP 2015-33473 A

  The problem to be solved in this way is that, in a three-dimensional measurement apparatus using sweep irradiation of an ultrasonic signal, means for easily improving the spatial resolution of the azimuth and the distance at the same time is not provided particularly in the short-distance observation space. .

  Accordingly, the present invention has been made to solve the above-described problems, and provides an ultrasonic transmission / reception apparatus capable of simultaneously improving the spatial resolution of azimuth and distance, particularly in a short-distance observation space. Objective.

  An ultrasonic transmission / reception apparatus according to the present invention is adapted to make a transmission direction of an ultrasonic signal correspond to a frequency, a transmitter in which a one-dimensional array transducer is divided into a plurality of partial apertures, and a transmission from the transmitter An ultrasonic transducer having a receiver that receives the reflected signal reflected by the target object and that corresponds to the frequency of the reception direction of the ultrasonic signal, the receiver receiving the reflected signal The receiver has a receiver width equal to or greater than the partial diameter of the receiver, and the receiver sensitivity is weighted with respect to the receiver width.

  In addition, the ultrasonic transmission / reception device according to the present invention drives the partial aperture in the transmitter in which the transmission direction of the ultrasonic signal corresponds to the frequency and the one-dimensional array transducer is divided into a plurality of partial apertures. The signal application time is set to a concave surface according to the partial aperture position on the one-dimensional array, and the transmitter includes an acoustic lens for converging the concave surface.

  In the ultrasonic transmission / reception apparatus according to the present invention, it is preferable that the signal waveforms of the signals in the respective directions for driving the partial aperture have a time waveform that allows an overlapping portion between the signal waveforms.

  Further, in the ultrasonic wave receiving apparatus according to the present invention, the receiver has a planar shape in which a plurality of the one-dimensional array transducers are arrayed in a direction orthogonal to the array direction of the inverting polarization elements of the one-dimensional array transducer. It is preferable to configure as a receiver.

  According to the present invention, in an ultrasonic wave receiving apparatus that measures a target object by transmitting and receiving an ultrasonic signal, by selecting the configuration of the receiver and the concave surface convergence, and the configuration of the drive signal, There is an advantage that the azimuth resolution and the observation area limitation can be improved simultaneously.

  Hereinafter, embodiments of an ultrasonic receiving apparatus according to the present invention will be described with reference to the drawings. The following embodiments do not limit the invention according to each claim, and all combinations of features described in the embodiments are not necessarily essential to the solution means of the invention. .

The figure for demonstrating the structure of the transmitter used for the ultrasonic transmission / reception apparatus which concerns on the 1st Embodiment of this invention. The figure which showed the directional characteristic by the transmitter of FIG. The figure for demonstrating the structure of the conventional receiver. The figure which showed the directivity characteristic of the transmission / reception comprehensive using the directivity of the conventional receiver. The figure which shows the drive signal waveform used with the ultrasonic wave transmission / reception apparatus which concerns on the 1st Embodiment of this invention. The figure which showed the directivity characteristic of the transmission / reception wave total at the time of using the drive signal waveform shown in FIG. The figure for demonstrating the structure of the receiver used for the ultrasonic transmission / reception apparatus which concerns on the 1st Embodiment of this invention. The figure which showed the directivity characteristic of the transmission / reception comprehensive at the time of using the receiver shown in FIG. Furthermore, the figure which showed the directional characteristic of the transmission / reception wave total at the time of using the drive signal waveform shown in FIG. The figure for demonstrating the structure of the acoustic lens for concave-surface convergence used for the ultrasonic transmission / reception apparatus which concerns on the 2nd Embodiment of this invention. The figure for demonstrating the time required for the conventional transmitter to complete the irradiation in all directions. The figure for demonstrating the time required for the transmitter used for the ultrasonic transmission / reception apparatus which concerns on the 3rd Embodiment of this invention to complete the irradiation to all directions. The figure for demonstrating the modification of the drive signal waveform used for the ultrasonic transmission / reception apparatus which concerns on the 3rd Embodiment of this invention. The figure which showed the directivity characteristic of the transmission / reception comprehensive at the time of using the drive signal waveform used for the ultrasonic receiving apparatus which concerns on the 4th Embodiment of this invention. The figure for demonstrating the structure of the receiver used for the ultrasonic transmission / reception apparatus which concerns on the 5th Embodiment of this invention. The figure for demonstrating the modification of the receiver used for the ultrasonic transmission / reception apparatus which concerns on this invention. The figure for demonstrating the whole structure of the ultrasonic receiver which concerns on the 5th Embodiment of this invention. The figure for demonstrating the further modification of the drive signal waveform used for the ultrasonic receiving apparatus which concerns on the 3rd Embodiment of this invention.

[First Embodiment]
FIG. 1 is a diagram for explaining the configuration of a transmitter used in the ultrasonic transmission / reception apparatus according to the first embodiment of the present invention, where n is the number of elements in the partial aperture, The partial aperture number is m, the total number of elements is mn, and the time length of the drive signal is T.

  As shown in FIG. 1, a transmitter 10 used in the ultrasonic wave transmitting / receiving apparatus according to the present embodiment includes a one-dimensional array transducer in which the polarization axis of the transducer 11 is inverted, and the one-dimensional array transducer. Is divided into a plurality of partial apertures 12, and a drive signal is applied to each partial aperture 12 to transmit ultrasonic waves.

  Further, the direction in which the ultrasonic wave is transmitted is changed by changing the frequency of the drive signal to be applied for each partial aperture 12. Furthermore, the distance resolution realized in the measurement using the transmitted ultrasonic waves is given by the signal time length T, and is approximately cT / 2 (c: sound velocity).

  FIG. 2 shows directivity characteristics according to the conventional multi-divided arrangement disclosed in Patent Document 3 (total number of elements 128, number of partial apertures 16, number of elements within partial apertures 8, signal length 32 period rectangular envelope).

  Thus, the directivity in the configuration of Patent Document 3 shows a strong unnecessary response strength as seen in FIG.

  On the other hand, Patent Document 4 discloses a configuration that uses the directivity of the receiver 120 by transmitting the wave with the configuration of FIG. 1 and receiving the reflected signal by the receiver 120 having a finite aperture shown in FIG. Has been.

  According to the configuration of this Patent Document 4 (transmitting: total number of elements 128, number of partial apertures 16, number of elements within partial apertures 8, signal length 32 period rectangular envelope), the width of the receiver shown in FIG. It is the same as the partial aperture width.

  According to the configuration of Patent Document 4, by using the directivity of the receiver 120, the directivity characteristics of the total transmission and reception are as shown in FIG.

  As shown in FIG. 4, according to the configuration of Patent Document 4, the first submaximal is suppressed to about −25 dB, but it is understood that the characteristics are insufficient similar to those of FIG.

  Therefore, in the first configuration of the ultrasonic wave transmitting / receiving apparatus according to the first embodiment of the present invention, the triangular weight shown in FIG.

  According to the first configuration of the ultrasonic wave transmitting / receiving apparatus according to the first embodiment of the present invention (transmitting: total number of elements 128, number of partial apertures 16, number of elements within partial aperture 8, signal length 64 period triangular envelope) The directivity characteristics of the transmission / reception wave synthesis are as shown in FIG. 6, and as is clear from FIG. 6, the sub-maximum is greatly suppressed.

  Furthermore, in the second configuration of the ultrasonic wave transmitting / receiving apparatus according to the first embodiment of the present invention, the receiver 20 has an opening width twice that of the conventional receiver 120 shown in FIG. The reflected signal reflected from the target object is received by the receiver 20 shown in FIG. 7 to which the triangular sensitivity weight is added on the opening.

  The second configuration of the ultrasonic wave transmitting / receiving apparatus according to the first embodiment of the present invention (transmitting: total number of elements 128, number of partial apertures 16, number of elements within partial aperture 8, signal length 32 period rectangular envelope) When the receiver 20 with the triangular sensitivity weight added thereto is used, as shown in FIG. 7, the receiver 20 has an opening width twice that of the conventional receiver 120 shown in FIG. Since the reflected signal reflected from the target object is received by the receiver 20 to which the triangular sensitivity weight 21 is added on the aperture, the first zero point in the reception directivity and the first submaximal position in the transmission directivity And the degree of suppression in the vicinity of the first zero point also increases, so that the directivity characteristics of the transmitted and received waves are as shown in FIG. 8, and the characteristics are improved from the results of Patent Document 4.

  In the third configuration of the ultrasonic wave transmitting / receiving apparatus according to the first embodiment of the present invention, the triangular weight waveform shown in FIG. 5 is used as the drive signal waveform.

  Driving with respect to the third configuration of the ultrasonic wave transmitting / receiving apparatus according to the first embodiment of the present invention (transmitting: total number of elements 128, number of partial apertures 16, number of elements within partial aperture 8, signal length 64 period triangular envelope) The directional characteristics of the total transmission / reception wave when the triangular weight waveform is used as the signal waveform are as shown in FIG. 9. From the result of Patent Document 4, the characteristics are greatly improved, and the ultrasonic transmission / reception wave according to the first embodiment is obtained. The first configuration of the apparatus is further improved, and the best characteristics among various configurations are realized.

[Second Embodiment]
Next, an ultrasonic transmission / reception apparatus according to the second embodiment having a configuration different from that of the first embodiment will be described. When measuring a short-distance object by the conventionally known method of Patent Document 2, it is necessary to converge with an acoustic lens, but it is difficult to change the convergence focal length in the convergence operation using the acoustic lens.

  Therefore, the application time of the signal for driving the partial aperture is set to a concave shape corresponding to the partial aperture position on the one-dimensional array by the variable delay line, and the delay time curvature is made variable, thereby making the focal length electronic. A configuration (see Patent Document 3) that can be changed automatically is known.

  However, according to the configuration of Patent Document 3, since the edge of the transmitter aperture does not contribute to the focal sound pressure, a significant resolution decrease from the limit resolution at the focal point was confirmed.

  FIG. 10 shows the configuration of the ultrasonic wave transmitting / receiving apparatus according to the present embodiment that prevents such a decrease in resolution at the focal point as a second embodiment.

  Unlike the converging configuration based only on the concave variable delay in Patent Document 3, the ultrasonic wave transmitting / receiving apparatus according to the present embodiment has a concave surface converging acoustic lens LZ for a specific focal length and a one-dimensional array as shown in FIG. And a correction delay circuit VD that gives a minute delay time for change (becomes a concave surface, a flat surface, or a convex surface) corresponding to a distance change from the fixed focal length.

  In the ultrasonic wave transmitting / receiving apparatus according to the present embodiment, since the acoustic lens LZ for converging the concave surface is provided, the sound waves a and d from the edge also reach the focal point o in the same phase, and the entire wave transmitter is transmitted. Since the aperture contributes to the formation of sound pressure at the focal point, a critical resolution determined by the aperture of the transmitter and the sound wave wavelength is achieved at the focal point.

[Third Embodiment]
Next, an ultrasonic wave transmitting / receiving apparatus according to the third embodiment using a drive signal different from the above-described embodiment will be described.

According to the conventionally known method of Patent Document 2, as shown in FIG. 1, since time mT (= L / c, c: speed of sound) is required for irradiation in one direction, the irradiation direction is set to the K direction. Assuming that the irradiation pulse length in each direction is T _n , as shown in FIG. 11, it takes a long time of m (T ₁ + T ₂ + −−−− + T _k ) to complete irradiation in all directions. Become.

  During this sound wave irradiation time, it is difficult to receive the reflected signal due to the interference by the transmission signal, and a wide range of non-measurable regions is generated in a short distance region.

  Therefore, as shown in FIG. 12, the drive signal used in the ultrasonic transmission / reception apparatus according to the present embodiment is transmitted from the transmitter 10 with the drive signal in each direction superimposed.

  By using such a drive signal, the signal drive time becomes mT1 + T2 +... Tk, which is significantly shortened compared to the configuration of the ultrasonic wave transmitting / receiving apparatus according to the second embodiment shown in FIG. The unobservable area is greatly reduced.

  Moreover, as shown in FIG. 13, by driving with a waveform having a different waveform for each partial aperture 12, ideal convergence in the vicinity can be realized without using the convergence acoustic lens LZ (Patent Document 5). However, the drive method shown in FIG. 12 can naturally be applied to this method, and in such a configuration, the nearby unobservable regions are also greatly reduced.

[Fourth Embodiment]
As shown in FIG. 4, according to the configuration of Patent Document 4 using the received wave directivity, the first submaximal is suppressed to about −25 dB, but it is not sufficient, similar to FIG. 2 with the configuration of Patent Document 3. It is a characteristic.

  Therefore, in the ultrasonic wave transmitting / receiving apparatus according to the fourth embodiment without using the reception directivity characteristic, the driving waveform is added with the triangular weight shown in FIG. 5 in the configuration disclosed in Patent Document 3. When the drive signal is used, the directivity characteristics are as shown in FIG. 14, which is greatly improved from the characteristics shown in FIG.

[Fifth Embodiment]
Further, as shown in Patent Document 3, a plurality of the one-dimensional array of receivers 20 shown in FIG. 7 are arranged in a direction orthogonal to the array direction of the inverting polarization elements, and a planar receiver 20 ′. In the configuration shown in FIG. 15 as well, the configuration of the present invention can be effectively applied, and the overall configuration of this embodiment is shown in FIG.

  The present invention is not limited to the configuration described above, and the processing for converting the driving waveform into a driving waveform to which the triangular weight shown in FIG. 5 is added is equivalently realized by convolution processing such as filtering processing or correlation processing. It is also possible.

  Further, in the configuration of the planar wave receiver 20 ′ shown in FIG. 15, the projection amount in one direction is applied by weighting processing such as placing the shape of the wave receiving surface or the sound absorbing material 22 as shown in FIG. In such a situation that lowers at the periphery, for example, a diamond shape or a disk shape, it is possible to further reduce the unnecessary response in directivity.

  Various effective weighting forms such as Hanning and Gauss are known.

  Further, in the configuration shown in FIG. 13, by driving the transmitter 10 with the long-time waveform or the weighted waveform shown in FIG. 18, the azimuth resolution can be improved as in the case of using the waveform of FIG. .

  The present invention has an advantage that the restriction on the azimuth resolution and the observation area can be improved at the same time with a simple configuration, and thus is effective for the advancement of a measurement apparatus using ultrasonic signals.

10 Transmitter,
11 vibrator,
12 partial caliber,
20, 20 ', 120 receiver,
21 Triangular sensitivity weight,
22 sound absorbing material,
30 Drive signal.

Claims (4)

The transmitter direction of the ultrasonic signal is made to correspond to the frequency, the transmitter in which the one-dimensional array transducer is divided into a plurality of partial apertures, and the reflection in which the signal transmitted from the transmitter is reflected by the target object In an ultrasonic transmitter / receiver equipped with a receiver for receiving a signal and corresponding a frequency to the receiving direction of the ultrasonic signal,
The ultrasonic wave transmitting / receiving apparatus, wherein the wave receiver has a wave receiver width equal to or larger than the partial aperture of the wave transmitter, and weights the wave receiving sensitivity to the wave receiver width. In the transmitter in which the transmission direction of the ultrasonic signal corresponds to the frequency and the one-dimensional array transducer is divided into a plurality of partial apertures,
An ultrasonic wave reception characterized in that an application time of a signal for driving the partial aperture is set in a concave shape according to a partial aperture position on a one-dimensional array, and the transmitter includes an acoustic lens for converging the concave surface. apparatus. The ultrasonic transmission / reception apparatus according to claim 1 or 2,
An ultrasonic wave transmitting / receiving apparatus characterized in that a signal waveform of a signal in each direction for driving the partial aperture has a time waveform that allows an overlapping portion between the signal waveforms. The ultrasonic transmission / reception apparatus according to any one of claims 1 to 3,
The ultrasonic wave is configured as a planar wave receiver in which a plurality of the one-dimensional array transducers are arranged in a direction orthogonal to the arrangement direction of the inverting polarization elements of the one-dimensional array transducer. Transmitter / receiver.

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