JP3465506B2 - Ultrasound imaging device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underwater imaging technique using sound wave propagation such as sonar, and more particularly to a technique for correcting image fluctuation caused by movement of a transducer.

[0002]

2. Description of the Related Art In the conventional motion correction techniques such as sonar, a method of mechanically controlling the attitude of the transducer to keep the attitude unchanged with respect to the underwater exploration area has been adopted. But,
The mechanical type is not necessarily an advantageous configuration because it is difficult to follow the problem of durability of the movable part and quick switching between a plurality of posture positions. Due to this problem, a technique for replacing the mechanical attitude control with electronic control without a moving part is required.

In the electronic control method, the elements of the wave transmitter / receiver are two-dimensionally arranged on a three-dimensional surface such as a sphere or a cylinder, and all changes due to movement are corrected by signal processing of transmission / reception signals. Since the entire transducer moves in the space together with the installed vessels and moving bodies, the displacement from the initial horizontal stationary position is constantly monitored to find various amounts to be corrected. Even if the wave transmitter / receiver is tilted, correction can be performed by changing the phasing addition conditions such as the delay time given to the transmission / reception signal for each element of the wave transmitter / receiver so that waves can always be transmitted / received in the same direction.

In order to maintain the same directivity even when the transducer is displaced (swing), the area on the transducer which is used to form the same transmitting or receiving beam geometrically (hereinafter Ideally, this is referred to as the "transmission / reception surface". For example, if the elements of the transducer are arranged on a spherical surface and the geometrical shape of the transmitting and receiving surface is part of a spherical shell cut out to have a circular contour, it will have the same directivity distribution with rotational symmetry. be able to.

However, in many cases, it is not possible to arrange the elements on the entire surface of the spherical surface due to the limitation in mounting. For example, a portion that should be secured for the connecting portion between the transducer and the ship bottom and a portion that is acoustically hidden by the shadow of the hull occur. For this reason, the widest transmitting / receiving surface and geometrical shape, which were ensured at the displacement position where the ship is swaying, cannot be ensured at another displacement position due to an invalid portion in which the elements are not arranged. In order to avoid this, if the size of the transmission / reception surface is narrowed, the transmission / reception gain is reduced. On the contrary, when the area where each element of the transmitter / receiver can be arranged is limited and the widest possible transmission / reception surface is required to secure the sensitivity of transmission / reception, the transmission / reception surface that always maintains the same directivity Cannot be secured.

As an example, when the transmitting / receiving surface is a rectangle whose width is wider in the horizontal direction than in the vertical direction when horizontally stationary, the directional main pole (acoustic beam) of the transmitting / receiving surface is sharp in the horizontal direction. , With a vertically flat, vertically flat directivity. If the entire transducer is tilted due to shaking, the three-dimensional directivity distribution (beam pattern) is also tilted in space, so that the beam that is sharp in the horizontal direction expands and conversely becomes narrow in the vertical direction. In the case of images such as sonar, the horizontal plane is usually used as the plane of the search image, so the width of the horizontal beam appears to have increased or decreased due to the shaking of the ship as compared to when the ship is stationary horizontally.

When the images of the search area obtained by transmitting and receiving a plurality of times are compared in the situation where this increase and decrease occur, the image of the reflective object detected by the image obtained by transmitting and receiving in a certain tilted state of the ship In an image obtained by transmitting and receiving in another tilted state, it will not be detected or will appear at another position in the image.

[0008]

In the above-mentioned prior art, the position of the image of the reflecting object changes, deforms, or disappears when the images are compared by a plurality of transmissions and receptions when the electronic motion correction is performed. There was a problem with the point. In addition, in order to suppress the change in the directivity distribution that causes this, there has been known a method of geometrically forming the same transmitting and receiving surfaces. However, the method of forming an effective equivalent transmission / reception surface by weighting often causes a decrease in the transmission / reception gain and a problem in that the detection ability is deteriorated.

In view of the above problems of the prior art, the present invention solves the problem of variation between a plurality of transmitted / received images while permitting a change in the directivity distribution without lowering the transmission / reception gain. is there.

[0010]

The first means of the present invention is as follows:
Transducer, displacement detection means for detecting displacement of the transducer, phasing addition means for compensating for wave propagation time difference between the transducers, image for converting output of phasing addition means into video signal A signal processing means and a display means for displaying an image,
According to the output of the displacement detection means, a predetermined arithmetic processing is added to the output of the phasing addition means.

Further, in the second means of the present invention, in the above-mentioned first means, the image signal processing means uses the output of the displacement detecting means and a corresponding position in the image and a weighting coefficient corresponding to the corresponding position. Is calculated and the output of the phasing addition means is multiplied by the weighting coefficient.

According to the third means of the present invention, in the second means of the present invention, the image signal processing means stores the video signal output to the display means in association with the space to be searched for. A storage position generation means for outputting the position of the storage area in the storage means from the output of the displacement detection means, and the weighting coefficient corresponding to the position in the storage area from the output of the displacement detection means. And a means for accumulating the product of the output of the phasing addition means and the weighting coefficient at the storage position of the storage area.

Further, in the fourth means of the present invention, in the third means of the present invention, the storage area in the storage means stores the cumulative value independently over a plurality of transmissions and receptions, and The stored value for each transmission / reception with the same corresponding position is accumulated over a plurality of transmissions / receptions, and the result is displayed.

Further, in the fifth means of the present invention, in the third means of the present invention, the storage area in the storage means stores the accumulated value independently over a plurality of transmissions and receptions, and the storage area in the image is stored. The product of the stored value of each transmission / reception in which the corresponding position is the same is multiplied by the coefficient determined for each transmission / reception, and the result of integrating the products is displayed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of an ultrasonic imaging apparatus of the present invention. Waves 1 propagating in exploration space such as undersea
Is detected by the transceiver group 100. The wave 1 is an acoustic wave generated by a sound source (for example, a ship or a moving body) in the exploration space or a backscattered wave (reflected wave, echo) of the wave generated by the transducer group 100.

The wave transmitter / receiver group 100 includes a plurality of wave transmitters / receivers 10.
1, 102 to 10n, the wave energy is converted into reception signals 151, 152 to 15n which are electric signals. The received signals 151, 152 to 15n are input to the phasing addition means 11. The phasing addition unit 11 is a unit that adds the received signals 151, 152 to 15n after delaying in order to compensate for the wave propagation time difference between the transmitter and the receiver with respect to a point or direction in the search space.

Various methods known in the prior art can be considered for phasing addition, and in addition to the means of simply sending the time and then taking the sum, in the transformed space represented by the fast Fourier transform method. The operation may effectively and equivalently delay or add. The phasing conditions (delay time difference, etc.) of the phasing addition means 11 are changed by the output of the displacement detection means 14. When the transducer fixed to the hull changes its position by shaking, the relationship of the distance and direction to the point or direction to be imaged in the exploration space changes.

The displacement detecting means 14 uses a satellite radio wave, a distance measuring method using a laser, a gyrator, a velocity detection by Doppler measurement for the seabed or seawater, etc. to detect displacement of the distance and azimuth. Make measurements to determine the spatial position. These measurement accuracies shall be provided as necessary within the range of 0.001 degrees to 2 degrees in terms of the inclination angle of the hull. The one tenth to one thousandth is appropriate in accordance with the beam azimuth resolution (angular resolution) produced by the phasing system. In terms of distance measurement accuracy, it is desirable that the wavelength of the received wave in the sea is about 1 / 10,000 to 1 / 10,000. The distance measurement accuracy must be replaced with the time accuracy calculated from the speed of sound in the sea, and must be higher than the time accuracy realized by the phasing addition means 11. If the displacement measurement is a velocity or acceleration measurement, there is a problem of setting an initial value and a problem of accumulation of measurement error. Therefore, the measurement needs to be an averaged process over a predetermined time length.

The output of the displacement detecting means 14 is also input to the image signal processing means 12. The image signal processing means 12 outputs the video signal 120 based on the output of the phasing addition means 11. The video signal 120 is an input signal for the display means 13 including a CRT or the like, and is a luminance-hue signal or RGB.
It is a data signal for forming a signal, and is a display means 13.
This is represented by a data signal stored in a VRAM (Video Random Access memory) built in the.

The output signal of the phasing addition means 11 may be a signal having the phase information of the carrier of the phasing addition signal, an envelope detection output, a correlation processing output when a chirp transmission signal or the like is used. In a typical case, the transmitter / receiver group 100
The pulse wave is transmitted by, and the resulting reflected pulse is received again by the transmitter / receiver group 100, and phasing addition and quadrature detection output are performed. Since the quadrature detection output retains the phase information of the carrier wave of the received signal, it can be divided into in-phase and quadrature (real part, imaginary part)
It is an output with components. The characteristic feature of the present embodiment is that the output signal of the phasing addition means 11 is subjected to predetermined arithmetic processing according to the output information of the displacement detection means 14 to perform image signal processing according to the spatial displacement of the transducer. To do.

FIG. 2 shows an arrangement example of the wave transmitter / receiver group 100 of this embodiment. The wave transmitter / receiver group 100 is composed of wave transmitters / receivers 101, 102, etc., each of which is composed of a piezoelectric vibrator having a rectangular wave transmission / reception surface. The wave transmitters / receivers are arranged such that a surface for transmitting / receiving waves is along a predetermined spherical surface 200, and are arranged so as to cover a part of the spherical surface 200 in a band shape as a whole. The entire wave transmitter / receiver group 100 is fixed and mounted by a casing (not shown) and a supporting member. The method of arranging the transmitter / receiver group is not limited to the arrangement method of FIG.

A frame 20 shows an example of a selection range of the transducers provided for the same phasing addition processing unit (processing unit for forming an acoustic beam in a specific direction). Further, it is assumed that the method of imaging by exploration is tomography, and the surface in the space to be imaged is included in the plane 201. The plane 201 is, for example, a plane parallel to the horizontal plane on the sea. Transducer group 10
In order to maintain substantially the same spatial resolution (directivity distribution) when the plane 0 changes to the position of the plane 211 relative to the transducer group 100 when 0 tilts with the displacement of the hull, for example, the frame 21 The transducer must be installed in the area such as the inside. However, because of the problem of fitting, the inside of the frame 21 cannot be completely filled with the transmitter / receiver, and only the polygonal area shown by the hatched portion 21H can be realized as an actually effective transmitting / receiving surface.

In order to eliminate the influence of such a change in the effective area and the shape, the selection range shown by the frame 20 is set to the range shown by the frame 22, and even if the transmitter / receiver group 100 is tilted. It is necessary to prevent the effective range of transmission and reception from being lost as shown by 23.

However, since the internal area of the frame 22 is always smaller than the internal area of the frame 20, the transmission / reception gain is reduced and the spatial resolution (directivity width of the acoustic beam) is deteriorated. This relationship will be described with reference to FIG. As is well known, the directivity width of an acoustic beam is widened in a shape with a narrow aperture or a taper weight.

Reference numerals 201 and 211 in FIG. 2 denote horizontal axes h in FIG.
Consider the case including. The aperture shown by the frame 20 forms the beam cross section 30 at a predetermined distance when viewed from the transducer. The beam cross section can be defined, for example, as to enclose the range in which the intensity decreases by −3 dB from the tip of the main pole of the directivity distribution centered on the sound axis s.

The axes 201 and 211 of FIG. 2 are orthogonal to the horizontal axis h.
Letting the axis perpendicular to V be the vertical axis v, the beam widths Hw and Vw in the respective axial directions can be obtained. If the range of the frame 22 is selected as an effective transmitting / receiving surface, the beam cross section 3
1 is obtained, and the widths of the beams are Hw 'and Vw'.
However, in the state where the directional sub-pole group is sufficiently suppressed, Hw
In many cases, <Hw ′ and Vw <Vw ′ are satisfied, and the area of the beam cross section 31 is larger than the area of the beam cross section 30, and the resolution is typically lowered. In such a situation, it is advantageous to use the beam cross section 30 having a high resolution when the transducer is horizontal and use the beam cross section 31 when the transducer is tilted. When it is possible to have a higher resolution than the imaging method that uses the frames 21 and 22 to always make the resolution constant, it is necessary to realize the imaging by a method that effectively uses the resolution for the video information.

Further, as another case, as shown in FIG. 4, the selection range of the aperture is fixed as the frame 20, and the transmission / reception and continuous transmission / reception are performed a plurality of times with respect to the area at the distance D from the transducer group 100. Consider a case in which the wave transmitter / receiver group 100 is tilted during the periodic reception. Here, the beam widths Hw ″ and Vw ″ of the beam cross section 30C when the transducer group 100 is tilted are merely said to have changed by projection on the axes h and v of the beam cross section, and the beam widths around the sound axis s. The resolution that is realized (for example, the small sampling volume of the space at a specific distance) is the same. Comparing before and after tilting, the detection point 40, which is a reflection source or a sound source in the hv plane, is outside the beam cross section 30 when horizontal and is not detected, but is detected at the beam cross section 30C when tilted. If both the phasing addition outputs obtained in both cases are images of the position of the sound axis s, in the tilted state, false detection is performed and a problem occurs.

This problem can be solved by grasping that the accuracy of the resolution in the horizontal direction is changed because the spread of the beam in the vertical direction is changed. When the imaging surface is in a plane including the horizontal axis h, when the transducer is horizontal, highly accurate information is given within a narrow width Hw, and when tilted, over a wide width Hw ′, It can be treated as giving ambiguous information with low accuracy. The degree of "accuracy" and "ambiguity" and the spread are the horizontal axes h of the beam cross sections 30 and 30C.
It is preferable to obtain it from the projection integral to. Transducer group 1
When 00 is horizontal, a large integrated value is obtained with a narrow width Hw, and when tilted, a small integrated value is obtained with a wide width Hw ″. In addition, the directivity distribution of the beam in the hv plane is represented by the horizontal axis h. You may use what carried out the projection integration to.

Since the displacement of the transducer group 100 changes with time, the beam cross section also changes with time. In the case of imaging by transmitting / receiving a pulse, the transducer group 100 is displaced during reception of a reflected wave for one transmission, so that the directivity of the beam changes at a short distance and a long distance.

First, the change of the beam cross section which changes with time will be considered with reference to FIG. The receiving surface indicated by the frame 20 indicates the position of the receiving surface at the moment when the reflected signal in the hv plane at the position of the distance D from the transducer group 100 is received. The receiving surface indicated by the frame 50 indicates the position of the receiving surface at the moment when the reflected signal in the h′-v ′ plane at the position of the distance D ′ from the transducer group 100 is received. The hv and h'-v 'planes are parallel and the new horizontal axis h'is in the same plane as the previous horizontal axis h. Frame 50
The receiving surface indicated by corresponds to the case where the wave transmitter / receiver group 100 is almost horizontal, and the beam cross section 51 is in a state where the beam cross section 51 spreads and has a small inclination.

Even if the transmitter / receiver group 100 is stationary, the distribution width of the projection integral changes as the distance increases. Therefore, it is practical to hold the above-mentioned projection integral result for each distance change and each inclination state. It is desirable to replace the distribution with an azimuth angle that does not change depending on the distance. That is, the horizontal beam width Hw ″ corresponds to the angular width θh ″, and Hw ″ ″ corresponds to the angular width θh ″ ″. Note that in FIG. 5, θh ″
> Θh ″ ″, and the beam cross section 30C at a short distance has a wider angular width in the horizontal direction.

Next, with reference to FIG. 5, the necessity of weighting distribution in the image at the time of integration due to a change in distance in the case of integrating images in a plurality of transmissions / receptions will be described. At the distance D when viewed from the transmitter / receiver group 100 during the first transmission / reception,
The intersection of the axis and the sound axis s is changed by the displacement of the transducer group 100.
The second time, it is assumed that the robot has moved to the intersection of the h'axis and the sound axis s at the distance D '. When trying to form a more accurate image by integrating the first and second images, the first time captured at a close distance, the projection integral value having a relatively small value is used as a weighting factor in the angle in the image. The phasing addition output is accumulated in a wide portion of the width θh ″, and the second time, the weighting factor value is large, and the angle width θ
The phasing addition output is accumulated in the narrow part of h ″ ′ ″. With these accumulation methods, the image captured when the image is ambiguous (thick beam) is accumulated thinly and widely, and the accuracy is high (beam sharp).
The captured images are sometimes dense and narrowly accumulated. Since the image captured blurry at a long distance and the image captured clearly at a short distance are weighted with good matching and added, the reliability of the integrated image is improved. By integrating the images, underwater noise and unnecessary reverberation can be efficiently suppressed.

FIG. 6 shows how the weighted distribution in the image changes due to the displacement of the transducer group 100 described above, taking the case of normal pulse transmission / reception as an example. The origin O corresponds to the position of the transducer group 100, and images the fan-shaped search area 60. The exploration region can be assumed to be, for example, a plane parallel to the sea surface, and the line segment OP corresponds to 500 m to 20 km on the actual sea. When composing an image, 50 to 10 can be sent and received once.
An image is formed by forming a plurality of acoustic (scanning, exploration) beams of about 00. Since the received echo can be obtained from a short distance, the images are arc 64 and arc 6 in order from the arc near the origin O.
It is drawn in the order of 5. The line segment Od corresponds to the distance D in FIG.
The line segment Od 'corresponds to the distance D'in FIG.

The imaging method will be described assuming that the azimuth centerline 66 located at the angle θc in the arc corresponds to the sound axis s in FIG. The arc portion 61 corresponds to the projection area of the beam cross section 30C in FIG. 5 onto the h axis. Similarly, the circular arc portion 62 corresponds to the projection area of the beam cross section 51 of FIG. 5 onto the h ′ axis. The hv plane and the h′-v ′ plane in FIG. 5 are planes for the sake of understanding, but strictly speaking, the coordinate system hv and the coordinate system h′v ′ are centered on the position of the transducer group 100. It is a curvilinear coordinate system provided on spherical shells having different radii, and it is desirable that the beam cross sections 30C, 51, etc. be part of spherical shells cut out in an elliptical shape.

Strictly speaking, the above projection integral should also be the projection of the spherical shell on a plane including the sound axes s, h and h '.
The shape of the projection should not be a curved line segment on the arc, but should be a flat area like a chord on the arc, but normally the angle width θ
Since h ″ and θh ″ ″ are about 1/100 to 20 degrees, the beam cross section is regarded as a plane or a part of a cylindrical surface with a gentle curvature, and the projection area, which is a surface, is a curved line on an arc. There is no practical problem even if it is regarded as a minute.

With respect to the beam in one azimuth direction, the phasing addition result is integrated as an image in order from the origin O in a continuous area including the arc portions 61 and 62 and shown by the envelope 63. Become. When a grid point in a polar coordinate system is provided to form an image, if the angular interval θi between the division points in the azimuth direction is narrower than the angular widths θh ″ and θh ″ ′ ″, the circular arc portion between adjacent beams The phasing addition results with weighted distributions represented by 61 and 62 are superimposed on each other.

An example of the weighting distribution corresponding to the arc portions 61 and 62 is shown in FIG. The weight coefficient Wd is on the vertical axis, and the azimuth angle θ in the image is on the horizontal axis. With the beam center position θc as the center of the distribution, the distribution curves 71 and 72 of the weighting coefficient Wd over the angular widths θh ″ and θh ″ ″ are assumed, and are indicated by white circles in the figure at the angular interval θi of the division points in the azimuth direction. The position weighting coefficient group is calculated.The product of the weighting coefficient group and the phasing addition output value is sequentially integrated for each beam as data for image formation. The signals can be used in various processing stages from the output of the phasing addition to the luminance signal of the image, but in the case of performing integration in multiple transmissions and receptions, the phasing addition that leaves the phase information. The output is appropriate, and it is desirable to use a complex output after detection by performing a complex frequency shift near DC on the frequency axis, etc. A complex storage area corresponding to the image area in Fig. 6 is secured, and the complex output is stored there. Accumulates, complex value when generating luminance signal of image With a magnitude to form a luminance signal (video signal) for display.

Next, weighting for each transmission / reception when integrating image information by a plurality of transmission / reception will be described. Information corresponding to one image is obtained during the transmission interval Ts of the transmitter / receiver group 100 while performing weighting and integration over the angular widths θh ″ and θh ″ ″. These are stored independently. , Data corresponding to the same position in the exploration space is integrated over a predetermined number of transmissions to form data for an integrated image.

FIG. 8 illustrates the weighting coefficient Wt for each transmission / reception of data corresponding to the same position in the search space. The vertical axis represents the value of the weighting coefficient Wt for each transmission / reception, the horizontal axis T represents time, Ts represents transmission interval, and Tw represents integration time. It represents that the mth transmission to the m + kth transmission within the time width of Tw are integrated with the same weight (for example, 1.0), and when the distribution 81 is used as a continuous window function. Equivalent to. This is a state in which each image data at the time indicated by a black dot is simply integrated.

Usually, Ts has a relatively long interval of about 1/10 to 15 seconds, so that there is a problem that the means for detecting the displacement of the transducer group 100 accumulates an error. When the displacement is obtained by integrating the time-differentiated amount such as force or velocity, the accumulated error of the time-differentiated amount with respect to the carrier wavelength of the transmission / reception pulse becomes the error of displacement detection. A predetermined limit occurs in the time length for which the displacement detection error can be guaranteed, and if Tw is secured longer than that, image data whose spatial positions do not match will be integrated. From this problem, it is effective to perform weighting within the integration time for integration. Among the image data to be integrated at the same time, the image data at the point m obtained by the oldest transmission and the image data at the point m + k obtained by the newest transmission are the image data obtained within the time width to be integrated. It is the image data that is most likely to be displaced from the relative position accuracy. Since the position accuracy in the relative consideration is lowered from the vicinity of the center to both ends in the integration time width, it is not advantageous to integrate them with equal weight. When it is considered that the image data at both ends of the time width has a ambiguity in the position accuracy when viewed from the center, for example, the distribution 82 is used as the window function and the time width Tw ′ based on the predetermined position accuracy is used. The more you give it, the more reliable it will be. Since the spread of the time width Tw ′ in consideration of the error is relative from the center, the integration is an operation of convolving the image data with a window function like the distribution 82 on the time axis.

FIG. 9 shows a structural example of the image signal processing means 12 for realizing the above signal processing. The image signal processing means 12 uses the output of the phasing addition means as the input of the arithmetic means 90. The calculation means 90 outputs the video signal 120 to the display means 120. The arithmetic means 90 is realized by a numerical arithmetic microprocessor or digital signal processor capable of floating point arithmetic. Further, the calculation means 90 is configured to be able to input / output with the storage means 93. The storage means 93 has storage areas 931 and 932 to 93 for internally accumulating image data.
With k, the output of the phasing addition means can be stored as image data weighted according to the displacement of the transducer group 100.

These image data are stored corresponding to continuous transmission / reception of k times, and old image data is overwritten and updated with new data each time new transmission / reception is performed.
Among the k pieces of image data, the image data corresponding to the same position in the search space can be convolved on the time axis by the product sum of the coefficient values of the window function described above. Further, a storage area for scan screen data (not shown) is secured in the storage means 93 as needed. In the storage area of the scanning screen data, the result of coordinate conversion and interpolation for converting the convolution result on the time axis from the k image data into the format of the video signal of the display means is stored, and the calculation means 90 is used. It is called and becomes the video signal 120.

By these operations, displacement information of the wave transmitter / receiver group 100 is output from the displacement detecting means 14 to the storage position generating means 91 and the coefficient generating means 92. When the displacement information of the transducer group 100 at the time when the signal for phasing addition is acquired is supplied in synchronization with the output of the phasing addition means, the storage position generating means 91 causes the storage position generating means 91 to store the storage position in the storage means 93. (Memory address etc.) is output. In the polar coordinate display image data as shown in FIG. 6, for example, the storage position is calculated and output by determining the azimuth angle θ, the distance from the origin O, the width of θh due to the inclination of the wave transmitting / receiving surface, and the like.

The coefficient generating means 92 uses the above-mentioned weight coefficient W.
Output d and Wt. In particular, since Wd outputs what is referred to by the displacement data of the inclination of the wave transmission / reception surface, the coefficient generating means 92 has a built-in storage means (not shown). Calculation of a time-consuming weight distribution by making it possible to refer to the table of the coefficient Wd obtained by projecting and integrating the beam cross section for each inclination state of the wave transmission / reception surface from the built-in storage means by the inclination displacement data. Can be omitted.

The signal input / output relationship of 90, 91, 92, 93 can be variously configured in addition to FIG. 9, but mainly in FIG.
As shown in, the essence of this configuration is to provide a means for accumulating the phased addition output in association with the position of the space and the position of the transmitting / receiving surface of the transducer.

[0046]

According to the present invention, it is possible to construct an image in consideration of a change in beam cross section due to displacement of a transmitter / receiver, which leads to a reduction in gain due to a shading process such as limiting the shape of a transmitting / receiving surface. It is possible to avoid, and it is possible to deal flexibly with outfitting restrictions. Also, by integrating the images,
Underwater noise and unnecessary reverberation can be efficiently suppressed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of image signal processing means of the present invention.

FIG. 2 is an explanatory view of a wave transmitter / receiver and a transmitting / receiving surface of the present invention.

FIG. 3 is an explanatory diagram of a beam cross section of a transmission / reception surface shape.

FIG. 4 is an explanatory diagram of rotation of a beam cross section due to rotation of a wave transmitter / receiver.

FIG. 5 is an explanatory diagram of rotation of a beam cross section due to movement of the transducer during movement and movement of a position.

FIG. 6 is an explanatory diagram of a process of forming image data according to the present invention.

FIG. 7 is an explanatory diagram of a distribution of weighting coefficients in the azimuth angle direction.

FIG. 8 is an explanatory diagram of convolution of image data in the time axis direction according to the present invention.

FIG. 9 is an explanatory diagram of a configuration example of image signal processing means of the present invention.

[Explanation of symbols]

11 ... Phasing addition means, 14 ... Displacement detection means, 100 ... Transducer.

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Claims (4)

(57) [Claims] 1. A plurality of transducers for transmitting and receiving ultrasonic waves,
Displacement detecting means for detecting displacement of the transducer, and
Phasing and adding means for compensating the difference in propagation time of ultrasonic waves between receivers
And an image for converting the output of the phasing addition means into a video signal
Signal processing means and table for displaying the video signal as an image
Indicating means, wherein the image signal processing means comprises the displacement
From the output of the detection means, the corresponding position in the image and the corresponding position
The weighting coefficient corresponding to the position is obtained, and the phasing addition means
Characterized in that the output is multiplied by the weighting coefficient
And ultrasonic imaging equipment. 2. The ultrasonic imaging apparatus according to claim 1,
The image signal processing means outputs the image data to the display means.
A memory hand that holds the video signal corresponding to the space to be searched
And the output of the displacement detection means, the case in the storage means.
Storage position generating means for outputting the storage area and the displacement detecting means
The weight according to the position in the storage area from the output of the stage
Coefficient generating means for outputting a weighting coefficient, and the phasing addition means
The product of the output and the weighting factor in the storage area
It includes a calculation means for accumulating at a position and obtaining a cumulative value.
Ultrasound imaging device to collect. 3. The ultrasonic imaging apparatus according to claim 2,
The storage area in the storage means is used for transmitting and receiving a plurality of times.
Or the accumulated value is stored, and the corresponding position in the image is
Store the same stored value for each transmission and reception for multiple times.
Characterized by displaying the result accumulated over reception
Ultrasonic imaging device. 4. The ultrasonic imaging apparatus according to claim 2,
The storage area in the storage means is used for transmitting and receiving a plurality of times.
Or the accumulated value is stored independently, and the corresponding value in the image is stored.
For each stored value of each transmission and reception that has the same position,
Calculate the product with the coefficient specified for transmission and reception and integrate the product
An ultrasonic imaging apparatus, which displays the result of the above.