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JPH10224880

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Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JPH10224880
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic array sensor, and more particularly to an ultrasonic array sensor which is used by an
automobile, a robot or the like for object recognition and which can electrically control
directivity.
[0002]
2. Description of the Related Art Heretofore, there have been the following ultrasonic array
sensors. That is, the ultrasonic array sensor arranges the ultrasonic transducers in a line and
operates the ultrasonic transducers to form a fan-shaped beam called a so-called fan beam. Here,
the ultrasonic transducer is composed of a piezoelectric element.
[0003]
A general characteristic of the ultrasonic array sensor is that it can electronically control
transmission and reception directivity. Here, the directivity of transmission refers to the change
in ultrasonic wave signal intensity depending on the direction, and the directivity of reception
refers to the change in reception sensitivity depending on the direction. For example, when
ultrasonic waves are generated in the same phase from ultrasonic transducers arranged in a line,
a fan beam having a shape as shown in FIGS. 7 and 8 is formed. Then, when an object is present
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in the inner area of the fan beam, the ultrasonic wave reflected from the object is detected by the
ultrasonic array sensor, and the object or the like can be recognized.
[0004]
However, the above-described prior art had the following disadvantages. That is, currently
available ultrasound transducers are intended solely for the emission of ultrasound into the air,
and their size (diameter) is usually determined by the wavelength of the generated ultrasound. It
is a long one. However, when arranging the waveguides emitting ultrasonic waves in a line, it is
desirable that the arrangement interval be equal to or less than a half wavelength of the
ultrasonic waves. In this case, when the waveguides are arranged at an arrangement interval
larger than a half wavelength of the ultrasonic wave and directivity is given to the ultrasonic
wave, a so-called side pole is generated as shown in FIG. The side lobe means that an ultrasonic
wave of a predetermined intensity is generated in a direction different from the intended
direction (main lobe direction). The side lobes can not be ignored, particularly when the direction
of travel of the ultrasonic waves is at an angle greater than or equal to a predetermined value
from the direction in which the ultrasonic waves travel.
[0005]
SUMMARY OF THE INVENTION It is an object of the present invention to ameliorate the
disadvantages of the prior art, and in particular to provide an ultrasonic array sensor which is
less susceptible to side lobes.
[0006]
SUMMARY OF THE INVENTION In order to achieve the above object, according to the invention
as set forth in claim 1, a tubular waveguide for guiding ultrasonic waves, and an end portion of
the waveguide are provided. And an ultrasonic transducer for transmitting an ultrasonic wave
toward the other end of the waveguide, wherein each of the waveguides comprises an array of a
plurality of waveguides equipped with the ultrasonic transducer. The shape of the other end of
the tube is substantially rectangular, and the other end of each of the waveguides is arranged in a
row, and one ends of adjacent waveguides in each of the waveguides have different directions
from each other An ultrasonic array sensor characterized in that it is extended is adopted.
[0007]
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2
By being configured as described above, the other end of the waveguide for emitting ultrasonic
waves has a narrow arrangement interval regardless of the size of the ultrasonic transducers.
On the other hand, one end of the waveguide on which the ultrasonic transducer is mounted is
distributed in a plurality of directions, and thus is separated from each other.
And a high frequency signal is given to each ultrasonic transducer, and an ultrasonic wave is
generated. The ultrasonic waves are transmitted inside the waveguide and emitted to the outside.
[0008]
The invention according to claim 2 adopts a configuration in which the arrangement interval of
the other end of each waveguide is equal to or less than a half wavelength of the ultrasonic wave
sent out by the ultrasonic transducer, and the other arrangement is described according to claim
1 It is similar to the invention of With the above configuration, the phase of the high frequency
signal applied to each ultrasonic transducer is slightly shifted for each ultrasonic transducer, so
that the direction of the ultrasonic waves can be changed, so-called sub-electrode Does not occur.
[0009]
The invention according to claim 3 adopts a configuration in which the length of the waveguide
is an integral multiple of the half wavelength of the ultrasonic wave generated by the ultrasonic
transducer, and the other configurations are described in claim 1 or 2 It is similar to the
invention of
[0010]
DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will
be described based on the drawings.
[0011]
As shown in FIG. 1, the ultrasonic array sensor 1 of the present invention is equipped with a
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tubular waveguide 3 for guiding ultrasonic waves and one end 7 of the waveguides 3a, 3b, 3c, An
ultrasonic transducer 5 for emitting an ultrasonic wave toward the other end 9 of the waveguides
3a, 3b, 3c, and a plurality of waveguides 3a, 3b, 3c equipped with the ultrasonic transducer 5 are
arranged It will be done.
Then, the shape of the other end 9 of each of the waveguides 3a, 3b, 3c is substantially
rectangular, and the other end 9 of each of the waveguides 3a, 3b, 3c is arranged in a row,
Among the tubes 3a, 3b and 3c, the end portions 7 of the adjacent waveguides are extended in
different directions.
[0012]
This will be described in detail below. The tubular waveguides 3a, 3b, 3c are configured such that
one end 7 has a substantially circular cross section, and the other end 9 is substantially
rectangular.
As shown in FIG. 1, each of the waveguides 3a, 3b and 3c has a waveguide 3a bent to one side, a
waveguide 3b bent to the other side, and a substantially linear waveguide 3c. The ultrasonic
array sensor 1 is configured by being used and combining them respectively. Here, the
waveguide 3a shown in FIG. 3 is a bent one, and the waveguide 3c shown in FIG. 4 is straight.
[0013]
As described above, the cross sections of the other end 9 sides of the waveguides 3a, 3b and 3c
are substantially rectangular, but more specifically, the circular cross section has a flatly
deformed shape. The area of the other end 9 of the waveguides 3a, 3b, 3c is configured to be the
same as the area of the one end 7 of the waveguides 3a, 3b, 3c. This is for preventing attenuation
of the ultrasonic wave sent from the ultrasonic transducer. Therefore, as shown in FIGS. 3 and 4,
the planar shape of each of the waveguides 3a, 3b and 3c is such that the width of the other end
9 as viewed from above is wider than the width of the one end 7 There is. However, the
waveguides 3a, 3b and 3c of the present invention are not limited to this, and may be so-called
"exponential horns".
[0014]
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In addition, ultrasonic waves are generated at one end 7 of the waveguides 3a, 3b, 3c toward the
inside of the waveguides 3a, 3b, 3c, and the other end 9 of the waveguides 3a, 3b, 3c. And an
ultrasonic transducer 5 (see FIG. 2) for emitting ultrasonic waves to the outside. The ultrasonic
transducer 5 has a diameter of about 10 mm. The ultrasonic transducer 5 is formed of a
piezoelectric element, and generates an ultrasonic wave of a predetermined frequency based on
an oscillation signal from an oscillator (not shown). Therefore, a predetermined electrode is
implanted in the ultrasonic transducer 5.
[0015]
Next, a method of configuring the ultrasonic array sensor 1 of the present invention by
combining the waveguides 3a, 3b, and 3c configured as described above will be described. In
each of the waveguides 3a, 3b and 3c, as shown in FIG. 1, the other end portions 9 of the
waveguides 3a, 3b and 3c adjacent to each other are arranged in a line, and abut each other. It is
joined. For example, as shown in FIG. 1, a waveguide 3a bent in the right direction is used as the
top waveguide. A straight waveguide 3c is used as the next second stage. Then, the waveguide 3b
bent to the left is used as the third stage. For convenience, in the case where the uppermost
waveguide 3a is No. 1 and the lowermost waveguide 3c is No. 8, the waveguides shown in FIG.
The third and sixth waveguides 3b (turned to the left) in the same shape as in the case where the
third waveguide 3a is turned upside down are used. And the 2nd, 5th, and 8th use the linear
waveguide 3c. However, the order of arrangement is not limited to this, and the waveguide 3b
bent to the left is arranged next to the waveguide 3a bent to the right, and then the linear
waveguide The order may be such that the tubes 3c are arranged.
[0016]
In the present embodiment, in addition to the above-described three waveguides 3a, 3b and 3c,
five waveguides are combined in the same order. Thus, the arrangement interval d of the other
end 9 of each of the waveguides 3a, 3b, 3c is substantially equal to the height of the rectangular
shape at the other end 9 of the waveguides 3a, 3b, 3c. As a result, the arrangement interval d at
the other end 9 of the waveguides 3a, 3b, 3c can be freely set by variously changing the height of
the other end 9 of the waveguides 3a, 3b, 3c. In particular, in the present embodiment, the
arrangement interval d at the other end 9 of the waveguides 3a, 3b, 3c is equal to or less than
the half wavelength of the ultrasonic wave generated by the ultrasonic transducer 5.
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[0017]
On the other hand, the end portions 7 of the waveguides 3a, 3b and 3c are separated from each
other as shown in FIG. 1, which is three types of ultrasonic array sensors 1 according to the
present embodiment. This is because the waveguides 3a, 3b, and 3c form one set, and these are
repeatedly arranged, and a predetermined gap is formed between the waveguides extending in
the same direction. That is, when one end 7 of the waveguides 3a, 3b, 3c equipped with the
ultrasonic transducer 5 is divided into three directions, theoretically the other end of the
waveguides 3a, 3b, 3c The arrangement interval d of 9 can be narrowed to about 1⁄3 of the
diameter of the ultrasonic transducer 5. Further, in the case where the end portions 7 of the
waveguides 3a, 3b, 3c are divided into five directions, the diameter can be narrowed to about 1⁄5
of the diameter of the ultrasonic transducer 5.
[0018]
In the present embodiment, the arrangement interval d of the other end portions 9 of the
waveguides 3a, 3b, 3c is about 4.2 [mm] or less. In this case, when the frequency of the
ultrasonic wave is 40 [KHz], its wavelength is about 8.4 [mm], which is set to half or less of this
wavelength. In the ultrasonic array sensor 1 of the present invention, the arrangement interval d
of the other end portion 9 of each of the waveguides 3a, 3b, 3c is not limited to the one
described above. That is, the settings may be changed according to the characteristics of the
ultrasonic transducer 5 used.
[0019]
Also, as described above, eight waveguides are arranged in the present embodiment, but more
waveguides may be arranged, and ultrasonic waves can be generated by a smaller number of
waveguides. An array sensor may be formed. In addition, in the above embodiment, the other
ends 9 of the waveguides 3a, 3b, 3c are arranged in a line, but the present invention is not
limited to this, and may be arranged in two lines or three lines.
[0020]
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Further, as the tube length of the waveguides 3a, 3b, 3c used for the ultrasonic array sensor 1, an
integral multiple of half wavelength of the wavelength of the ultrasonic wave is most efficient.
This is to cause a so-called resonance phenomenon in the waveguides 3a, 3b, 3c. Therefore, when
manufacturing the ultrasonic array sensor 1, waveguides each having an integral multiple of half
wavelength and the same length are used, and the other end of each of the waveguides is
flattened to form a rectangular shape. At the same time, a part of the plurality of waveguides may
be bent at a predetermined curvature to combine them. Then, after combining the respective
waveguides, the joint portion is solidified and fixed with a molten metal or a resin having a high
specific gravity. Thereby, the resonance phenomenon between the waveguides is effectively
prevented.
[0021]
Next, a case where object recognition and the like are performed by the ultrasonic array sensor 1
configured as described above will be described. First, predetermined high frequency signals are
applied to the ultrasonic transducers 5 provided in the waveguides 3a, 3b, 3c. At this time, the
high frequency signal is a so-called sine wave, and the phases of the high frequency signals
applied to all the ultrasonic transducers 5 are made to coincide. And the phase of the ultrasonic
wave emitted from the other end 9 of each waveguide 3a, 3b, 3c is detected, and if different, it is
corrected. As a cause of the difference in phase, a change in the tube length of the waveguides
3a, 3b, 3c at the time of processing of the waveguide, a change in the tube length due to bending,
etc. can be considered.
[0022]
As described above, after the phase is corrected, sine wave signals whose phases are shifted are
applied to the ultrasonic transducers 5 mounted on the respective waveguides 3a, 3b, 3c. For
example, the phase difference of the ultrasonic transducer of the waveguide 3a at the top (see
FIG. 1) is zero, and the phase difference of the waveguide 3c of the ultrasonic transducer at the
bottom is π. Then, by shifting the phase of each ultrasonic transducer in the middle portion in
proportion to a value between 0 and π, the traveling direction of the wave front of the ultrasonic
wave is inclined. At this time, by setting the phase difference arbitrarily, the directivity of the
ultrasonic wave can be set arbitrarily.
[0023]
Then, the ultrasonic wave emitted from the ultrasonic array sensor 1 strikes an obstacle or the
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like and is reflected, and the reflected wave is detected by the ultrasonic array sensor 1 to
recognize the presence of an object.
[0024]
Further, as shown in FIG. 5, the bent shape of the waveguide is preferably as straight as possible,
as shown in FIG.
Therefore, the distribution direction of one end of the waveguide may be limited to three or two
directions. In addition, as the shape of the waveguide, as shown in FIG. 6, a substantially conical
shape may be used. In this waveguide, an ultrasonic transducer is mounted at one end (thick
end), and the waveguides are joined at the other end (thin end). At this time, as the respective
waveguides, substantially straight ones are used, and the opening directions of the other ends
also have a predetermined angle with each other. However, by setting the size of the opening
smaller than the wavelength of the ultrasonic wave, the direction of the open part hardly affects
the directivity of the ultrasonic wave, and even if there is a slight angle difference, It functions
well as an acoustic array sensor.
[0025]
The present invention is configured and functions as described above. According to this, the
shape of the other end of each waveguide is made substantially rectangular, and the other end of
each of these waveguides is arranged in a line. Since the ends of the adjacent waveguides in each
of the waveguides are arranged to extend in different directions from each other, the
arrangement interval of the other ends of the waveguides to which the ultrasonic waves are
emitted is set. , And can be freely set without being directly limited to the size of the ultrasonic
transducer. In addition, since an ultrasonic transducer generally used conventionally can be used
as it is, an excellent effect can be obtained that the manufacturing cost can be suppressed.
[0026]
Moreover, since the arrangement interval of the other end of the waveguide through which the
ultrasonic wave is emitted is made shorter than the half wavelength of the ultrasonic wave, socalled sub-poles (side lobes) are not generated, and object recognition with high reliability is
performed. It produces an excellent effect of being able to
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[0027]
Furthermore, since the length of the waveguide is made an integral multiple of the half
wavelength of the ultrasonic wave, an excellent effect can be obtained that the ultrasonic wave
passing through the bent waveguide can be efficiently transmitted.
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