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DESCRIPTION JPH1020033

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DESCRIPTION JPH1020033
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic wave transmitting apparatus which transmits electric waves while changing directivity
electrically and three-dimensionally, and an ultrasonic wave sensor using the same.
[0002]
2. Description of the Related Art FIG. 9 is a block diagram showing a conventional ultrasonic
wave transmitting apparatus which transmits ultrasonic waves while changing the directivity
electrically and three-dimensionally.
[0003]
The conventional ultrasonic wave transmission device 80 refers to the transmission wavefronts
821 to 82n in the same one direction (hereinafter referred to as the x-axis direction).
The direction perpendicular to the x-axis direction (hereinafter referred to as the y-axis direction
and the z-axis direction) while facing the A plurality of ultrasonic transducers 841 to 84n
arranged in a plane at a constant interval L2 and ultrasonic transducers 841 to 84n, and the
ultrasonic transducers 841 to 84n have a constant phase difference .delta. The phase shifters
861 to 86 n are caused to oscillate by being shifted one by one, and the control unit 88 for
changing the phase difference δ of the phase shifters 861 to 86 n.
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[0004]
The ultrasonic transmitter 80 is known as a so-called "phased array" and can scan directivity in a
desired three-dimensional direction only by electrically changing the phase difference δ without
requiring a mechanical structure. .
[0005]
However, the conventional ultrasonic wave transmitter 80 has the following problems.
[0006]
The phase shifters 861,..., And the control unit 88 cause the ultrasonic transducers 841,... To
oscillate with a predetermined phase difference δ, and change the phase difference δ within a
predetermined range.
In order to realize such a function, an extremely complicated circuit configuration is required.
Moreover, since the phases of the ultrasonic transducers 841, ... are all different, the phase
shifters 861, ... are required for each of the ultrasonic transducers 841, ....
[0007]
In addition, as many phase shifters 861, ... as the number of ultrasonic transducers 841, ... are
required in order to obtain a flatter flat wave by increasing the number of ultrasonic transducers
841, ... It will be a major obstacle.
[0008]
SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an
ultrasonic transmitting apparatus capable of changing the directivity of ultrasonic waves
electrically and three-dimensionally in a simple configuration, and an ultrasonic sensor using the
same. It is to provide.
[0009]
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An ultrasonic transmitting apparatus according to the present invention comprises a plurality of
ultrasonic transducers and a variable frequency oscillating unit.
The plurality of ultrasonic transducers are disposed in a conical shape at regular intervals in the
oblique direction of the one direction while the transmission wavefronts are directed in the same
direction.
The variable frequency oscillation unit can oscillate the plurality of ultrasonic transducers at the
same frequency and change the frequency.
[0010]
Ultrasonic waves of the same frequency are transmitted from the plurality of ultrasonic
transducers. At this time, the ultrasonic waves transmitted from the respective ultrasonic
transducers travel in the direction in which the phases coincide with each other. This is because
the ultrasonic waves in the direction in which the phases do not match weaken each other. In
addition, when the frequency of the ultrasonic wave is changed, the direction in which the phases
of the ultrasonic waves coincide is changed based on the shape of the ultrasonic transducer.
Therefore, by changing the frequency of the ultrasonic waves, the directivity of the ultrasonic
waves can be changed.
[0011]
Also, the variable frequency oscillating unit may be singular. Further, the plurality of ultrasonic
transducers may obtain the maximum output at the same wavelength of the ultrasonic wave, and
the wavelength may be matched with the component in the one direction at the predetermined
interval.
[0012]
An ultrasonic sensor according to the present invention includes the ultrasonic wave transmitting
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apparatus according to the present invention, an ultrasonic transducer for reception, a reception
signal processing unit, and a control unit. The ultrasonic transducer for reception is provided at
the apex of a cone formed by a plurality of ultrasonic transducers for transmission. The received
signal processing unit processes the signal received by the ultrasonic transducer. The control
unit controls the reception signal processing unit and the variable frequency oscillation unit.
[0013]
DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an
embodiment of an ultrasonic wave transmitting apparatus according to the present invention.
FIG. 2 is a circuit diagram showing an example of the ultrasonic wave transmitter of FIG. FIG. 3 is
an external perspective view showing an example of the ultrasonic wave transmission apparatus
of FIG. Hereinafter, it demonstrates based on these drawings.
[0014]
The ultrasonic wave transmitting apparatus 10 according to the present invention refers to the
transmitting waves 121 to 12 (2 n), ... in the same one direction (hereinafter referred to as the xaxis direction). The ultrasonic transducers 141 to 14 (2 n),... And the ultrasonic transducers
141,... Arranged at a constant interval L in a diagonal direction in the x-axis direction while being
directed to) oscillate at the same frequency f And a variable frequency oscillating unit 16 which
makes the frequency f variable. In addition, although the ultrasonic transducer | vibrator is
arrange | positioned so that it may also become conical in fact on the z-axis side, in FIG.1 and
FIG.2, it abbreviate | omits for convenience.
[0015]
The ultrasonic transducers 141 may be general ones, but preferably oscillate in a wide band. The
variable frequency oscillation unit 16 is connected to a general oscillation circuit 161, a variable
resistor 162 that changes the oscillation frequency of the oscillation circuit 161, a transistor 163
that amplifies the output waveform of the oscillation circuit 161, and a base side of the transistor
163. And a pulse transformer 167 for obtaining an AC waveform from the output waveform of
the transistor 163.
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[0016]
In general, the circuit that changes the frequency has a simpler configuration than the circuit
that changes the phase difference. Moreover, since the variable frequency oscillation part 16
connects ultrasonic transducer 141, ... in parallel, one piece may be sufficient. Therefore, the
ultrasonic transmitting apparatus 10 has a very simple configuration as compared with the
conventional ultrasonic transmitting apparatus 80 (FIG. 9).
[0017]
As shown in FIG. 3, the ultrasonic transducers 141,... Are attached so that they have a conical
shape at a constant interval L in the oblique direction of the x-axis direction while directing the
transmitting wavefronts 121,. It is buried in the pedestal 20. The mounting pedestal 20 is formed
in a conical shape as a whole by, for example, a synthetic resin, and the embedded surfaces 201
to 203 are provided in a step-like shape. The embedded surfaces 201 to 203 are portions in
which the ultrasonic transducers 141,... Are embedded, and have a ring shape with different
diameters. The variable frequency oscillation unit 16 may be built in the mounting pedestal 20 or
may be placed outside the mounting pedestal 20 and connected by a cable. In addition, in FIG. 3,
although the code | symbol is attached | subjected only to the ultrasonic transducers 141-146 (n
= 3), the thing of the same shape as the ultrasonic transducers 141, ... is an ultrasonic transducer
altogether.
[0018]
4 to 6 are explanatory diagrams showing the operation principle of the ultrasonic wave
transmission device according to the present invention. Hereinafter, it demonstrates based on
these drawings.
[0019]
The component in the x-axis direction of the fixed interval L is Lx, and the wavelength of the
ultrasonic wave US is λ. Also, in order to simplify the description, two ultrasonic transducers, 14
m and 14 (m + 1), are used. FIG. 4 [1] is the case of λ = Lx. The ultrasonic waves US in this case
travel in the x-axis direction since the phases are aligned in the x-axis direction. FIG. 4 [2] is the
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case of λ <Lx. The ultrasonic waves US in this case are inclined in the negative direction of the yaxis relative to the x-axis direction and the phases are aligned, so the ultrasonic waves US travel
in that direction. FIG. 4 [3] is the case of λ> Lx. The ultrasonic waves US in this case are inclined
in the positive direction of the y-axis relative to the x-axis direction and the phases are aligned, so
the ultrasonic wave US proceeds in that direction.
[0020]
Next, the phenomenon of FIG. 4 will be generalized and explained based on FIG. In FIG. 5, the
angle between the x-axis direction and the traveling direction of the ultrasonic wave US is the
directivity angle φ, and the angle between the y-axis direction and the direction in which the
ultrasonic transducers 14m and 14 (m + 1) are provided is It is assumed that the arrangement
angle θ. Here, with respect to the ultrasonic waves US transmitted from the ultrasonic
transducer 14 (m + 1), a perpendicular line passing through the ultrasonic transducer 14 m is
drawn, and this intersection point is set to a. Then, the wavelength λ of the ultrasonic wave US
coincides with the distance from the ultrasonic transducer 14 (m + 1) to the intersection point a.
Therefore, the following equation is obtained.
[0021]
λ = L · sin (θ−φ) (1)
[0022]
Further, assuming that the velocity of sound is v, the wavelength λ is λ = v / f, and this can be
substituted into the equation (1) to obtain the following equation.
[0023]
φ = θ−sin−1 {v / (f · L)} (2)
[0024]
As is clear from the equation (2), since θ, v and L are constants, the directivity angle φ can be
changed by changing the frequency f.
[0025]
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Here, it is assumed that the ultrasonic transducers 14m have the same frequency characteristics.
Each of the ultrasonic transducers 14m,... Has directivity that most strongly outputs ultrasonic
waves in the x-axis direction perpendicular to the transmission surface.
On the other hand, the ultrasonic transducers 14m,... Have a wavelength .lambda.0 at which the
maximum output can be obtained.
Therefore, if the x-axis direction component Lx of the fixed interval L and the wavelength λ0 are
made to coincide with each other, the ultrasonic wave US traveling in the x-axis direction can be
obtained in the case of λ0 = Lx shown in FIG.
This ultrasonic wave US is the strongest one obtained when the transducers 14m,... This is
because the direction in which the maximum output of each of the ultrasonic transducers 14m,...
Can be obtained matches the traveling direction of the ultrasonic wave US at the wavelength
.lambda.0 in which the maximum output can be obtained.
[0026]
Since the ultrasonic transducers 14m,... Are arranged in a conical shape centered on the x-axis,
the direction in which the ultrasonic waves US are actually rotated is the direction in which the
ultrasound US is rotated about the x-axis in FIG. It is. FIG. 6 is a cross-sectional view showing the
actual traveling direction of ultrasonic waves US, that is, the transmission region. 6 [1] and [2]
correspond to FIGS. 4 [1] and [2], respectively. FIG. 6 [1] is the case of λ = Lx. In this case, the
transmission region A of the ultrasonic wave by the ultrasonic transmission device 10 has a
linear shape extending in the x-axis direction. FIG. 4 [2] is the case of λ <Lx. The transmission
region A in this case is in the form of an umbrella that spreads more in the y-axis direction than
in the x-axis direction. Thus, by changing the frequency f, the directivity of the ultrasound
changes to open and close the umbrella. It is sufficient to change the frequency f in the range of
λ ≦ Lx.
[0027]
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Needless to say, the ultrasonic wave transmission device according to the present invention is not
limited to the above embodiment. For example, the variable resistor 162 may be replaced with a
collector-emitter resistance of a transistor, and the resistance value of the collector-emitter
resistance may be changed by controlling the base voltage of the transistor with a
microcomputer.
[0028]
FIG. 7 is a block diagram showing an embodiment of an ultrasonic sensor according to the
present invention. FIG. 8 is an external perspective view showing an example of the ultrasonic
sensor of FIG. Hereinafter, it demonstrates based on these drawings. However, the same parts as
in FIG. 1 and FIG.
[0029]
In the ultrasonic sensor 30 according to the present invention, the transmitting wavefronts 121
to 12 (2 n),. The same as the ultrasonic transducers 141 to 14 (2 n),... And the ultrasonic
transducers 141,. Variable frequency oscillator 16 oscillated at f and variable frequency f,
ultrasonic transducer 32 for reception provided at the apex of a conical body formed by
ultrasonic transducers 141, and ultrasonic transducer A reception signal processing unit 34 for
processing the signal received by 32 and a control unit 36 for controlling the reception signal
processing unit 34 and the variable frequency oscillation unit 16 are provided. In addition,
although the ultrasonic transducer for transmission is arrange | positioned so that it may become
conical also in the z-axis side in fact, in FIG. 7, it abbreviate | omits for convenience.
[0030]
As shown in FIG. 8, the mounting pedestal 20 is formed in a conical shape as a whole, and the
embedded surfaces 200 to 203 are provided in a step-like manner. The embedded surfaces 200
to 203 are portions in which the ultrasonic transducers 32 and the ultrasonic transducers 141,...
Are embedded, and have a ring shape with different diameters. The ultrasonic transducer 32 is
provided at the apex of a cone formed by the ultrasonic transducers 141 by being embedded in
the embedded surface 200 while the wave receiving surface 321 is directed in the x-axis
direction. The variable frequency oscillation unit 16, the reception signal processing unit 34, and
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the control unit 36 may be built in the mounting pedestal 20, or may be placed outside the
mounting pedestal 20 and connected by a cable.
[0031]
Since the ultrasonic transducer 32 is provided at the apex of the conical body formed by the
ultrasonic transducers 141,..., Not only does it not interfere with the ultrasonic waves transmitted
from the ultrasonic transducers 141,. It is easy to receive the ultrasonic waves arriving from.
[0032]
The reception signal processing unit 34 is general, and includes a detection circuit, an
amplification circuit, an A / D converter, and the like.
The reception signal of the ultrasonic transducer 32 is processed by the reception signal
processing unit 34 to be reception data, and is output to the control unit 36. The control unit 36
is, for example, a microcomputer, calculates the distance to the reflector of the ultrasonic wave
based on the received data, or transmits the ultrasonic wave from the ultrasonic transducers
141,. And the function of changing the frequency f.
[0033]
For autonomous operation of a mobile, both a sensor for wide area information acquisition and a
sensor for local information acquisition are required. The ultrasonic sensor according to the
present invention can acquire wide area information and local information by itself, and
therefore can be suitably used as an obstacle sensor for an autonomous mobile robot or an
approach sensor for a car.
[0034]
According to the ultrasonic transmitting apparatus of the first to third aspects and the ultrasonic
sensor of the fourth aspect, while the transmitting wavefront is directed to the same direction,
the straight lines at a constant interval in the oblique direction of the one direction Changing the
frequency of the ultrasonic waves, since the ultrasonic vibrators are arranged in a matrix and a
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variable frequency oscillating unit which oscillates the ultrasonic vibrators at the same frequency
and changes the frequency. The directivity of ultrasound can be three-dimensionally changed by
In addition, since a simple circuit for changing the frequency is used instead of the complex
circuit for changing the phase difference as in the prior art, the configuration can be simplified.
Therefore, downsizing, weight reduction and price reduction of the apparatus can be achieved. In
addition to this, by causing all ultrasonic transducers to oscillate at the same frequency, it can be
extremely simplified as compared to the prior art in which all ultrasonic transducers are
oscillated with different phase differences, so that directivity accuracy and control Performance
such as speed can be easily improved.
[0035]
According to the ultrasonic wave transmission device of the second aspect, by making the
variable frequency oscillation unit single, it is possible to have an extremely simple configuration.
This effect becomes more pronounced as the number of ultrasonic transducers increases, so it
can be suitably used for a so-called two-dimensional array sensor.
[0036]
According to the ultrasonic transmission apparatus of the third aspect, it is assumed that a
plurality of ultrasonic transducers can obtain maximum output at the same wavelength of
ultrasonic waves, and the wavelength is made to coincide with the component in the one
direction at the predetermined interval. Thereby, the strongest ultrasonic wave that can be
obtained by combining a plurality of ultrasonic transducers can be transmitted in one direction.
Therefore, it can be suitably used for, for example, a proximity sensor of a car, which needs to
transmit the strongest ultrasonic wave forward.
[0037]
According to the ultrasonic sensor of the fourth aspect, the ultrasonic transducer for
transmission is provided by providing the ultrasonic transducer for reception at the apex of the
cone formed by the plurality of ultrasonic transducers for transmission. Not only does not
become an obstacle to the ultrasonic waves output from the sensor, it can easily receive
ultrasonic waves arriving from a wide range.
[0038]
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Brief description of the drawings
[0039]
1 is a block diagram showing an embodiment of the ultrasonic wave transmission device
according to the present invention.
[0040]
2 is a circuit diagram showing an example of the ultrasonic transmission apparatus of FIG.
[0041]
3 is an external perspective view showing an example of the ultrasonic wave transmission device
of FIG.
[0042]
4 is an explanatory view showing the operation principle of the ultrasonic wave transmission
device according to the present invention, FIG. 4 [1] is when the ultrasonic wave travels in the xaxis direction, FIG. 4 [2] is the ultrasonic wave than in the x-axis direction In the case where the
ultrasonic wave travels in the negative direction of the y-axis, as shown in FIG. 4 [3], the
ultrasonic wave travels in the positive direction of the y-axis while traveling in the positive
direction.
[0043]
5 is an explanatory view showing an operation principle of the ultrasonic wave transmission
device according to the present invention, which generalizes the phenomenon shown in FIG.
[0044]
6 is a cross-sectional view showing an ultrasonic wave transmission region in the ultrasonic wave
transmission apparatus of FIG.
FIG. 6 [1] shows the case where the transmission region is linear, and FIG. 6 [2] shows the case
where the transmission region is umbrella-like.
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[0045]
7 is a block diagram showing an embodiment of an ultrasonic sensor according to the present
invention.
[0046]
8 is an external perspective view showing an example of the ultrasonic sensor of FIG.
[0047]
9 is a block diagram showing a conventional ultrasonic transmission apparatus.
[0048]
Explanation of sign
[0049]
10 Ultrasonic wave transmitters 121 to 12 (2 n) Transmitting wave surface 141 to 14 (2 n)
Ultrasonic transducer 16 for transmission Variable frequency oscillator 30 Ultrasonic sensor 32
for ultrasonic wave transducer L for fixed interval f Frequency
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