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JP2001305217

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DESCRIPTION JP2001305217
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to
ultrasonic beam formation of a phased array of ultrasonic transducers, and more particularly to
an ultrasonic phased array transducer which is reduced in size and weight by an array
connection method and a driving method. .
[0002]
2. Description of the Related Art In water, speedometers, tidal meters, etc., which use the Doppler
effect of ultrasonic waves are often used.
[0003]
A typical transducer used for this type of speedometer or tidal meter is an ultrasonic Doppler
transducer with four orthogonal beams.
[0004]
A typical structure incorporates four disk-shaped piezoelectric ceramic ultrasonic transducers,
arranged so that each emitting surface faces the beam forming angle.
[0005]
The directivity width of the ultrasonic beam is determined by the drive frequency and the outer
diameter of the ultrasonic transducer, but the directivity width and the drive frequency are set
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from the conditions for increasing the Doppler effect, and then the outer diameter of the
ultrasonic transducer is determined .
[0006]
Therefore, by determining the outer diameter of the ultrasonic transducer, the shape and size of
the ultrasonic Doppler transducer that forms four orthogonal beams are approximately
determined.
[0007]
Also, a disk-shaped ultrasonic Doppler transducer that forms two beams with one phased array is
disclosed in Japanese Patent Laid-Open No. Hei 4-238499.
[0008]
In the disclosed example, as shown in FIG. 11, when the values on the COS curve are weights W1
to W10 for the ultrasonic transducers arranged in the lateral direction, the beam patterns are as
shown in FIG. In the graph, the main pole of the ultrasonic beam is formed in both directions of
30.degree. Left and right around the 0.degree. Axis of the graph (i.e., the direction perpendicular
to the center of the ultrasonic transducer).
[0009]
Also, if the electrical connection is changed, ultrasonic beams are similarly formed in both the
front and back directions in the longitudinal direction.
[0010]
However, the conventional typical ultrasonic Doppler transducer for forming the four orthogonal
beams described above has the following disadvantages.
[0011]
That is, the ultrasonic Doppler transducer comprising four ultrasonic transducers has a planar
area four or more times the radiation area of the ultrasonic transducer and a mass four or more
times, and the size and weight of the ultrasonic transducer should be reduced. I can not do it.
[0012]
Also, in the case of using the disk-like ultrasonic Doppler transducer that forms two beams in the
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one-phase array of the disclosed example, two phased arrays are required to obtain four
orthogonal beams, so that In addition to the defect that the planar area is doubled, there is a
defect that the directivity synthesis circuit becomes very complicated.
[0013]
The present invention is to provide an orthogonal four-beam ultrasonic Doppler transducer
having a minimum size and a minimum mass by using one phased array and the connection
method of the front and back and the simplest directivity synthesis circuit. .
[0014]
SUMMARY OF THE INVENTION According to the present invention, in an ultrasonic phased array
transmitter-receiver which is a minimum ultrasonic Doppler transmitter-receiver, wiring of a
surface of a phased array in which ultrasonic transducers are arranged and a switching circuit
And phase distribution is made in the direction perpendicular to the wire connection direction
with the phasing circuit, three kinds of beams of front and rear 2 beams, front 1 beam and rear 1
beam are formed in the upper right and lower left direction of phase distribution direction.
Create a phase distribution in the direction perpendicular to the wire connection direction with
the phasing circuit, and create three types of beams: left and right two beams, one left beam, and
one right beam orthogonal to the three types of beams in the upper left and lower right
directions of the phase distribution direction. Form.
[0015]
Of these various beams, after transmitting orthogonal 2 beams of front and rear 2 beams by
front and back 2 right and left beams by back simultaneously, front 1 beam and back 1 beam and
back left 1 beam and right 1 beam orthogonal 4 beams Simultaneously obtain independent beam
signals of
[0016]
That is, according to the present invention, ultrasonic transducers having electrodes on both end
surfaces are vertically aligned from the top to the bottom, and horizontally from the right to the
left. In the ultrasonic phased array transducer arrayed in a rectangular array on a plane, the
array interval between the two directions is set to [1/21/2 ▒ 1 / (2 О 21/2)] ?, where ? is the
wavelength of the underwater acoustic wave. (N + M-1) by electrically connecting the electrodes
of the first row in each row and the transducers in the first row and the lower row of the Mth
row starting from the transducers in the first row and the lower row. The surface connection
group is electrically connected in the lower left diagonal direction of the left one column lower
row every other row starting from the vibrator of Nth row and each row and the vibrator of Mth
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row each row when the electrode on the back side is seen from the surface And (N + M-1) back
connection groups, and in the front connection group which is orthogonal between the front and
back, 1 + 4 k, 2 + 4 k, 3 + 4 k, 4 + 4k (k = 0, 1, иии), 1 + 4l, 2 + 4l, 3 + 4l, 4 + 4l (l = 0, 1, и и и и и и и in
the back surface wiring group, input and output terminals connected together in the front and
back 4 groups) As F1, F2, F3, F4 and R1, R2, R3, R4, any one of the input / output terminals R1R3 or R2-R4 of the vibrator not connected between F1-F3 and F1-F3 , Or input and output
electrical signals to any one of two circuits between F2-F4 and between the input / output
terminals R1-R3 of the vibrator not connected between F2-F4 and between F2-F4 or between R2R4. Then, the conversion polarity of electroacoustics is alternately distributed positive and
negative at intervals of one jump in each line of back and forth connection, and has main pole in
upper right lower left 2 directions orthogonal to surface connection direction centering on
perpendicular line of acoustic radiation surface center 2 beams and 2 beams And forming an
orthogonal 4 beam of the two beams having a main pole in the upper left lower right two
directions simultaneously.
[0017]
In the ultrasonic phased array transducer according to the present invention, the array shape is a
rectangle whose number of ultrasonic transducers is N О M (N ? M) in length and width, a
square of N = M, or one side of the square array It is characterized in that it can be made into a
pseudo-circular shape composed of ultrasonic transducers located within the circumference.
[0018]
In addition, the array shape affects the submaximal levels of beam directivity, and a circular
shape is preferable to a rectangular shape at a lower level.
[0019]
The present invention relates to the ultrasonic phased array transducer of the rectangular array,
square array, and pseudo-circular array, wherein the input and output terminals F1 and F3 are
the first transformer, and F2 and F4 are the second transformer. , R1 and R3 of the third
transformer, R2 and R4 of the fourth transformer, are connected to the respective balancing
circuit windings of the fourth transformer, and the neutral points of the balancing circuit
windings are all grounded. The influence of the input / output signal of one side to the input /
output terminal of the other side is eliminated, and the output signals of the unbalanced winding
forming the pair of transformers are S1, S2, S3, S4, Means for giving a phase difference of one of
the signals to the other signal by 90 degrees, and means for adding and subtracting the signal
given the phase difference of 90 degrees and the other signal, Means for giving a 90.degree.
Phase difference to one signal of the other and a 90.degree. Phase difference. And a signal and
the other signal means for adding and subtracting the each of the four orthogonal beams and
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obtaining a signal for each separate and independent one-beam from the output of the adding
means and the subtracting means.
[0020]
The directivity characteristics of the ultrasonic phased array transducer according to the present
invention are characterized by the transducer array, the lower right diagonal linear connection of
the array surface, and the lower left diagonal linear connection of the array back surface.
[0021]
The directivity of orthogonal two beams for transmission is formed as follows, and the main pole
orientation is calculated as follows.
[0022]
That is, as shown in FIG. 4, the polarity of the transmission sound pressure of the ultrasonic
transducer is alternately reversed in the positive and negative direction at two connection
intervals in the front and back direction of the surface connection by the input of the electric
signal between the input and output terminals F1 and F3. Distribution between the input and
output terminals R1 and R3 so that positive and negative are alternately inverted at two
connection intervals in the left and right direction of the back surface connection by the input of
an electric signal between the input and output terminals R1 and R3 The connected transducers
and the transducers connected between R1 and R3 do not overlap, and the polarity distributions
of F1 to F3 and R1 to R3 are distributed as shown in FIG.
[0023]
As shown in FIG. 6, the directivity due to such distribution is directivity of two beams B1 and B3
in the front and back direction of the perpendicular to the center of the acoustic radiation surface
and two beams B2 and B4 in the left and right direction orthogonal to this. Form
[0024]
The main pole orientation and perpendicular angle of one beam, that is, the main pole azimuth
angle (▒ ?o) can be determined from the result of directivity calculation with the wire
connection spacing b and the wavelength of the underwater acoustic wave ?. It will be.
[0025]
sin ?o = 1 / (4b / ?) (1)
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[0026]
From this, when the wire connection distance is b = 0.5?, ?o = 30 degrees becomes the most
useful main pole azimuth angle, and from ?o = 90 degrees when b = 0.25?, when b = 0.75?
The main pole azimuth angle of ?o = 20 ░ of is an available range.
By the way, when b is set to 0.75 ? or more, a large solid angle submaximity appears at a high
level, which is not suitable for practical use.
[0027]
The arrangement interval d of the transducers with respect to the above-described connection
interval b is 21/2 times b from FIG.
[0028]
d = 21 / 2b = 21/2 (0.5 ▒ 0.25) ? = [1/21/2 ▒ 1/1 / (2 О 21/2)] ?
[0029]
Furthermore, according to the present invention, one beam directivity 4 form for receiving the
ultrasonic phased array transducer is formed as follows by the reception phasing process.
[0030]
That is, as for the polarity of the received sound pressure of the ultrasonic transducer, the input
and output terminals F1 and F3 of the first transformer, F2 and F4 of the second transformer, R1
and R3 of the third transformer When R2 and R4 are connected to the respective balanced
circuit windings of the fourth transformer, and the output signals of each pair of unbalanced
windings are S1, S2, S3 and S4, The polarity of the output signal with respect to the input sound
pressure to the surface (the same as the sound emission surface), that is, the conversion polarity,
and as in the case of transmission, S1 and S2 alternate between positive and negative alternately
at two connection intervals in the front and rear direction Distribution, and S3 and S4 are
distributed so that positive and negative are alternately reversed at two connection intervals in
the lateral direction, and as a result, two beam directivity is formed in each of the front, rear, left
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and right as in the case of transmission. Do.
Polarity distribution in the direction of the connection number direction of polarity is ?positive,
positive, negative, since the S1 signal is the connection combination of the odd connection
number and the S2 signal is the connection connection of the even connection number. ,
Negative, positive, positive, negative, negative,.
[0031]
Furthermore, since the positive and negative polarities are equivalent to the relationship between
the phase angle of 0 degrees and 180 degrees, the connection number distribution of the phase
angles replaced with ?0, 0, 180, 180, 0, 0, 180, 180, ... ?.
[0032]
Connection number distribution of phase angle by addition of -90 degrees phase difference to S1
signal and addition processing with S2 signal in reception phasing processing is ??90, 0, 90,
180, ?90 (= 270), 0 ( = 360), 90 (= 450), and so on, and the forward beam directivity in the
front-rear direction shown in FIG. 7 is formed by the distribution advancing in this connection
number direction.
Moreover, the connection number distribution of the phase angle by the ?90 degree phase
difference addition to the S1 signal and the subtraction process with the S2 signal (adding ?180
degrees to S2) is ??90, ?180, 90 (= ?270), It becomes 0, -90, -180, 90 (= -270), ... ", and the
backward beam directivity in the front-rear direction is formed by the distribution lagging in this
connection number direction.
[0033]
Similarly, with respect to the polarity distribution of the entire left and right direction by both S3
and S4 signals, the phase advance of the connection number distribution of the phase angle by
addition processing of -90 degrees to the S3 signal and addition and subtraction processing of
the S4 signal. The left and right beam directivity and the right beam directivity are formed
independently of each other.
[0034]
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The main pole orientations of orthogonal four-beam directivity before and after transmission /
reception are located in each quadrant of four quadrants divided by the vertical and horizontal
axes of the array with the perpendicular direction of the center of the transducer array as the
origin. The better the directivity of the beam is, the larger the cut in the directivity characteristic
in the perpendicular direction is.
[0035]
In order to increase the notches in the perpendicular direction, the number of positive and
negative conversion polarity of the sound receiving surface and the number of positive and
negative signals giving a phase difference of 90 degrees may be equal. It is desirable to make the
range equal.
[0036]
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be
described below with reference to the drawings.
[0037]
FIG. 1 is a transducer connection diagram of a rectangular array ultrasonic phased array
transducer according to a first embodiment of the present invention, in which the number of
array of ultrasonic transducers 2a constituting the ultrasonic phased array 1a is N = 16. , M = 12.
[0038]
FIG. 2 is a transducer connection diagram of the square array ultrasonic phased array transducer
according to the second embodiment of the present invention, in which the number of array of
ultrasonic transducers 2b constituting the ultrasonic phased array 1b is n = n. The case of '= 12
is shown.
[0039]
FIG. 3 is a transducer connection diagram of the quasi-circular array ultrasonic phased array
transducer according to the third embodiment of the present invention, wherein the maximum
number of arrayed ultrasonic transducers 2c constituting the ultrasonic phased array 1c is n. The
case of = n '= 12 is shown.
[0040]
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FIG. 4 is a connection diagram at the time of transmission of the ultrasonic phased array
transducer according to the third embodiment of the present invention, and in this connection
state, the front-rear direction two beams directivity shown in FIG. Orthogonal four-beam
directivity which simultaneously forms two-beam directivity (not shown) is obtained.
[0041]
FIG. 5 is a connection diagram at the time of reception of the ultrasonic phased array transducer
according to the third embodiment of the present invention, and in this connection state, the
front beam directivity and the back beam shown in FIGS. 9 and 10 Directivity, and orthogonal
four-beam directivity composed of left and right beam directivity and right beam directivity (not
shown) similar to the front and back direction are obtained.
[0042]
Hereinafter, the third embodiment of FIG. 3 will be described as a representative.
[0043]
The ultrasonic transducers 302 are arrayed with vertical and horizontal gaps 331 and 332, and
the front surface is straightly connected in the lower right direction by connection 341 to draw
out 15 connection number terminals, and the back side is straight in the lower left direction by
connection 342 Connect one by one and pull out 15 connection number terminals.
[0044]
Connection terminals on the front surface are shorted together by 1, 5, 9, 13 (1 + 4k, (k = 0, 1, ...)
in connection number to make an input / output terminal F1, and similarly 2 + 4k are shorted
together Similarly, 3 + 4k is set to F3 and 4 + 4k to F4, and the connection on the back side is
made by combining connection numbers 1 + 4k '(k' = 0, 1, ...) into R1, 2 + 4k '. Let R2,3 + 4k 'be
R3,4 + 4k' be R4 to form a total of eight input / output terminals.
[0045]
The ultrasonic transducer 302 uses a longitudinal vibration mode of piezoelectric ceramic, and
the electrode shape at both ends is square.
The electrode shape, that is, the radiation surface shape of the piezoelectric ceramic, can ensure
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insulation between adjacent electrodes by making the lead wire circular on the front and back of
the electrode surface so that it is easy to connect and wire, or octagonal with four corners. It is
practical to have an assembly structure.
[0046]
The arrangement interval was a half wavelength of the acoustic wave in water, that is, ? / 2
arrangement, and in order to reduce the interference of the lateral vibration, vibration blocking
material such as cork was put in the gaps 331 and 332 between the ultrasonic transducers.
[0047]
FIG. 4 is a connection diagram at the time of transmission of the ultrasonic phased array
transducer according to the third embodiment of the present invention.
Input / output terminals (hereinafter abbreviated as terminals) F1 and F3 in which connections
on the front and back surfaces of the quasi-circular array ultrasonic phased array 301 are
summarized are windings for balanced circuit of the transformer 5a (hereinafter abbreviated as
balanced windings). ), R1 and R3 are connected to the balanced winding of the transformer 5c,
and the neutral point (center tap: C. T) of the balanced winding is grounded.
[0048]
The purpose of grounding the neutral point is to prevent mutual interference of the signals on
the front and back and to form a balanced circuit with a load in which transducers with inverted
conversion polarity are connected in series, resulting in a stable balanced signal. is there.
[0049]
The balanced winding and the pair of windings are the unbalanced circuit winding (hereinafter
referred to as unbalanced winding) which can be easily switched between transmission and
reception, and the odd connection number of the front surface and the odd connection number of
the rear surface not overlapping with this And input and output respective signals.
[0050]
Next, terminals F2 and F4 are connected to the balanced winding of transformer 5b, R2 and R4
are connected to the balanced winding of transformer 5d, and the neutral point is grounded to
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balance input terminals of transmission R1, R3 and F1. , F3 are grounded.
[0051]
The unbalanced windings of the transformers 5a and 5c are connected to the transmission /
reception switching circuits 6a and 6b, connected to the transmission signal input by the internal
changeover switches 7a and 7b, and the signal from the external transmitter (not shown)
Transmit at the same time.
[0052]
In the connection of FIG. 4, all the vibrators are driven to efficiently and simultaneously form the
directivity of two beams in the front-rear direction and two beams in the left-right direction
shown in FIG.
[0053]
The connections to the transformers 5a and 5c can be alternately switched and transmitted, and
directivity can be formed alternately by two beams in the front-rear direction and two beams in
the left-right direction.
[0054]
FIG. 5 is a connection diagram at the time of reception of the ultrasonic phased array transducer
according to the third embodiment of the present invention.
At the time of reception, each of the unbalanced windings of transformers 5a and 5c is directly
connected to each of the unbalanced windings of transformers 5b and 5d via changeover
switches 7a and 7b of transmission / reception switching circuits 6a and 6b. It is connected to
the reception phasing circuits 8a and 8b.
[0055]
The reception phasing circuit 8a receives the reception signals from the transformers 5a and 5b,
shifts the phase of the output signal of the transformer 5a by the 90 degree phase shift circuit
9a, and makes a phase difference of 90 degrees with respect to the output signal of the
transformer 5b. The two signals are added by the adding circuit 10a, and the signals forming the
front beam directivity in the front-rear direction shown in FIGS. 7 and 9 are output, and the two
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signals are subtracted by the subtracting circuit 11a. A signal for forming the back and forth
beam directivity shown in FIG. 10 is output.
[0056]
Similarly, the reception phasing circuit 8b receives the signals from the transformers 5c and 5d
and forms left and right beam directivity and right beam directivity by the 90 ░ phase shift
circuit 9b, the adder circuit 10b and the subtraction circuit 11b. Output each signal individually.
[0057]
In the connection at the time of reception, each ultrasonic transducer is driven by the input
sound pressure by the incoming sound wave, and the reception signal of the amplitude and
phase distribution by the drive signal is output. Output is performed only on the front surface
connection, the back surface connection is grounded as a neutral point, and the output of the
received signal on the back surface left and right direction is performed only with the back
surface connection, and the surface connection is grounded as a neutral point. Since there is no
interference between the output signals on the back and front sides, and the beam directivity
signals in each direction are independent, it is possible to obtain the outputs of the front and
back beams and the left and right beams simultaneously.
[0058]
As described above, according to the present invention, the front surface and the back surface of
the ultrasonic transducer of the phased array are connected, and two beams in the front-rear
direction are formed using the lower right oblique connection on the surface. By forming two
beams in the left-right direction using the lower left oblique connection on the back side, it
becomes possible to form four orthogonal beams in the front, rear, left, and right with the size of
one array, and the same drive frequency and the same beams In the case of an orthogonal fourbeam transducer having a width, the shape can be minimized.
[0059]
In the present invention, for convenience of explanation, ?the front surface is represented by
the lower right diagonal linear connection to the front and rear direction beam of the surface
connection number, and the rear surface is represented by the lower left diagonal linear
connection to the left and right direction beam of the rear connection number?. However, the
range based on simple rearrangement, for example, according to "the left-right direction beam of
the surface connection number with the lower left oblique straight wire connection, the back
direction of the back connection number with the lower right oblique linear connection" A range
is included without departing from the scope of the present invention.
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