JP2789329B2 - Ultrasonic transmitter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic transmitting apparatus for transmitting ultrasonic waves while changing its directivity electrically.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram showing a conventional ultrasonic transmitting apparatus for transmitting an ultrasonic wave while changing its directivity electrically.

[0003] A conventional ultrasonic transmitter 80 has a wavefront 82.
The same way the 1～82N (hereinafter, referred to as the x-axis direction.) Of the left x axis direction toward the vertical direction (hereinafter, referred to as y-axis.) A plurality of which are linearly arranged at regular intervals L ₂ in Ultrasonic vibrators 841 to 84n and ultrasonic vibrators 841 to 84n
n and the ultrasonic vibrator 841
８４84n are shifted by a constant phase difference δ and oscillate, and the phase difference δ between the phase shifters 861 差 86n is
And a control unit 88 that changes

The ultrasonic transmission device 80 is known as a so-called "phased array", and does not require a mechanical structure, but scans the directivity in a desired direction only by electrically changing the phase difference δ. it can.

[0005]

However, the conventional ultrasonic transmitter 80 has the following problems.

[0006] The phase shifters 861,... And the control unit 88 oscillate the ultrasonic transducers 841,... With a constant phase difference δ, and change the phase difference δ within a certain range. 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,.
41,...

The phase shifters 861,...
41,... Are required.
It becomes a big obstacle when trying to obtain a flatter plane wave by increasing the number of 1,.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ultrasonic transmitting apparatus which has a simple structure and can electrically change the directivity of ultrasonic waves.

[0009]

An ultrasonic transmitter according to the present invention includes a plurality of ultrasonic transducers and a variable frequency oscillator. The plurality of ultrasonic transducers are linearly arranged at regular intervals in a diagonal direction of the one direction while the wave transmitting surfaces are directed in the same one direction. The variable frequency oscillator can oscillate a plurality of ultrasonic transducers at the same frequency and change the frequency.

[0010] Ultrasonic waves of the same frequency are transmitted from a plurality of ultrasonic transducers. At this time, the ultrasonic waves transmitted from the respective ultrasonic transducers travel in directions in which the phases match each other. This is because ultrasonic waves in directions in which the phases do not match each other weaken each other. Further, when the frequency of the ultrasonic wave is changed, the direction in which the phases of the ultrasonic wave coincide with each other changes based on the shape in which the ultrasonic vibrator is provided. Therefore, the directivity of the ultrasonic wave can be changed by changing the frequency of the ultrasonic wave.

Further, the variable frequency oscillator 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 correspond to the one-directional component at the fixed interval.

[0012]

FIG. 1 is a block diagram showing one embodiment of an ultrasonic transmitting apparatus according to the present invention. FIG. 2 is a circuit diagram showing an example of the ultrasonic transmission device of FIG. FIG.
FIG. 2 is an external perspective view illustrating an example of the ultrasonic transmission device in FIG. 1. Hereinafter, description will be made based on these drawings.

The ultrasonic transmitting apparatus 10 according to the present invention linearly extends at a constant interval L in an oblique direction in the x-axis direction while keeping the wave transmitting surfaces 121 to 12n in the same one direction (hereinafter referred to as the x-axis direction). The ultrasonic oscillators 141 to 14n are provided and a variable frequency oscillator 16 that oscillates the ultrasonic oscillators 141 to 14n at the same frequency f and changes the frequency f.

The ultrasonic transducers 141 to 14n may be general ones, but preferably oscillate in a wide band. The variable frequency oscillator 16 includes a general oscillation circuit 161, a variable resistor 162 that changes the oscillation frequency of the oscillation circuit 161,
Transistor 16 amplifies output waveform of oscillation circuit 161
3, a resistor 164, 165 and a diode 166 connected to the base of the transistor 163, and a pulse transformer 167 for obtaining an AC waveform from the output waveform of the transistor 163.

Usually, the circuit for changing the frequency has a simpler configuration than the circuit for changing the phase difference. Also, the variable frequency oscillator 16 may be a single variable oscillator because the ultrasonic oscillators 141 to 14n are connected in parallel. Therefore, the ultrasonic transmission device 10 has an extremely simple configuration as compared with the conventional ultrasonic transmission device 80 (FIG. 6).

As shown in FIG. 3, the ultrasonic transducers 141 to 141
146 (n = 6) are buried in the mounting base 20 so that the wave transmitting surfaces 121 to 126 are directed straight in the x-axis direction at regular intervals L in the oblique direction in the x-axis direction.
The mounting pedestal 20 is made of, for example, a synthetic resin, and has a step-like buried surface 201-2 in which the ultrasonic vibrators 141-146 are buried.
06 and through holes 207 and 208 for attaching to desired portions by bolts or the like. The variable frequency oscillator 16 may be built in the mounting base 20, or may be placed outside the mounting base 20 and connected by a cable.

FIGS. 4 and 5 are explanatory diagrams showing the operation principle of the ultrasonic transmitting apparatus according to the present invention. Hereinafter, description will be made based on these drawings.

The component in the x-axis direction at a constant interval L is Lx, and the wavelength of the ultrasonic wave US is λ. For simplicity of description, the number of ultrasonic transducers is 14 m and 14 (m + 1). FIG. 4A shows a case where λ = Lx. The ultrasonic wave US in this case proceeds in the x-axis direction because the phases are aligned in the x-axis direction. FIG. 4B shows the case where λ> Lx. In this case, the ultrasonic wave US is inclined in the positive direction of the y-axis rather than in the x-axis direction and has the same phase, and thus proceeds in that direction. FIG. 4 [3] shows that λ <Lx
Is the case. In this case, the ultrasonic wave US is inclined in the negative direction of the y-axis rather than in the x-axis direction and has the same phase, and thus proceeds in that direction.

Next, the phenomenon of FIG. 4 will be generalized and described with reference to FIG. In FIG. 5, the angle between the x-axis direction and the traveling direction of the ultrasonic wave US is defined as a directivity angle φ, and the angle between the y-axis direction and the direction in which the ultrasonic vibrators 14m and 14 (m + 1) are provided. The arrangement angle is θ. Here, the ultrasonic vibrator 14
With respect to the ultrasonic wave US transmitted from (m + 1), a perpendicular line passing through the ultrasonic transducer 14m is drawn, and this intersection is defined as a.
Then, the wavelength λ of the ultrasonic wave US becomes the ultrasonic transducer 14 (m
+1) and the distance from the intersection a. Therefore,
The following equation is obtained.

Λ = L · sin (θ−φ) (1)

If the sound speed is v, the wavelength λ is λ = v /
Since f, this is substituted into equation (1) to obtain the following equation.

Φ = θ−sin ⁻¹ {v / (f · L)} (2)

As is clear from equation (2), θ, v, L
Since is a constant, the directional angle φ can be changed by changing the frequency f.

Here, it is assumed that the ultrasonic transducers 14m,... Have the same frequency characteristics. Each ultrasonic transducer 14m, ...
Has the directivity of outputting an ultrasonic wave most strongly in the x-axis direction perpendicular to the transmission plane. On the other hand, the ultrasonic transducer 14m,
Have the wavelength λ ₀ at which the maximum output is obtained. Therefore, when the x-axis direction component Lx of the constant interval L is made to coincide with the wavelength λ ₀ , an ultrasonic wave US traveling in the x-axis direction is obtained when λ ₀ = Lx shown in FIG. 4A. This ultrasonic US
.. Are the strongest obtained when the entirety of the transducers 14m,. Because each ultrasonic transducer 14
This is because the direction in which the maximum output of m,... is obtained matches the traveling direction of the ultrasonic wave US at the wavelength λ _{0 at} which the maximum output is obtained.

The present invention is, of course, not limited to the above embodiment. For example, the variable resistor 162 may be replaced with the 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.

Further, the present invention can be suitably used for an obstacle sensor for an autonomous mobile robot, a proximity sensor for an automobile, and the like.

[0027]

According to the ultrasonic transmitter of the present invention, a plurality of ultrasonic transmitters arranged linearly at regular intervals in a diagonal direction in one direction while keeping the transmitting surface in the same one direction. Since it has an ultrasonic oscillator and a variable frequency oscillator that oscillates these ultrasonic oscillators at the same frequency and makes the frequency variable, it is possible to change the directivity of the ultrasonic wave by changing the frequency of the ultrasonic wave. it can. Moreover, since a simple circuit for changing the frequency is used instead of a complicated circuit for changing the phase difference as in the prior art, the configuration can be simplified. Therefore, reduction in size, weight, and cost of the device can be achieved. In addition, by oscillating all ultrasonic transducers at the same frequency, it is possible to greatly simplify the conventional technique in which all ultrasonic transducers oscillate with different phase differences. Performance such as speed can be easily improved.

According to the ultrasonic transmitting apparatus of the second aspect,
By using a single variable frequency oscillator, an extremely simple configuration can be achieved. This effect becomes more remarkable as the number of ultrasonic transducers increases.

According to the ultrasonic transmitting apparatus of the third aspect,
It is assumed that a maximum output is obtained at the same wavelength of the ultrasonic wave of the plurality of ultrasonic transducers, and the wavelength is matched with the one-directional component at the constant interval to obtain a combination of the plurality of ultrasonic transducers. The strongest possible ultrasonic wave can be output in the one direction. Therefore,
It can be suitably used for, for example, an approach sensor of an automobile, which needs to transmit the strongest ultrasonic wave forward.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an ultrasonic transmission device according to the present invention.

FIG. 2 is a circuit diagram showing an example of the ultrasonic transmission device of FIG.

FIG. 3 is an external perspective view illustrating an example of the ultrasonic transmission device of FIG. 1;

FIG. 4 is an explanatory diagram showing the operation principle of the ultrasonic transmission apparatus according to the present invention. FIG. 4 [1] shows the case where the ultrasonic wave travels in the x-axis direction, and FIG. FIG. 4 [3] shows a case where the ultrasonic wave is inclined more in the negative direction of the y axis than in the x axis direction.

FIG. 5 is an explanatory diagram showing the operation principle of the ultrasonic transmission device according to the present invention, and is a generalization of the phenomenon shown in FIG.

FIG. 6 is a block diagram showing a conventional ultrasonic transmission device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Ultrasonic transmission apparatus 121-12n Transmission plane 141-14n Ultrasonic transducer 16 Variable frequency oscillator L Fixed interval f Frequency

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuichi Umemi 2-1, Sakuranamiki, Tsuzuki-ku, Yokohama, Kanagawa Prefecture Inside the Technical Research Institute, Suzuki Motor Corporation (72) Inventor Mutsuo Ohara 2nd Sakuranamiki, Tsuzuki-ku, Yokohama, Kanagawa Prefecture No. 1 Suzuki Technical Research Institute (56) References JP-A-63-181600 (JP, A) JP-A-4-62468 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) ) G01S 7/523 G01S 7/521 H04R 17/00 332

Claims (3)

(57) [Claims] 1. A plurality of ultrasonic transducers linearly arranged at regular intervals in a diagonal direction in one direction while the transmitting surface is directed in the same one direction, and these ultrasonic transducers are operated at the same frequency. An ultrasonic transmission device comprising: a variable frequency oscillator that oscillates and varies the frequency. 2. The ultrasonic transmitting apparatus according to claim 1, wherein the number of the variable frequency oscillator is one. 3. The ultrasonic transmitting apparatus according to claim 1, wherein the plurality of ultrasonic transducers obtain a maximum output at the same wavelength of the ultrasonic wave, and the wavelengths and the components in the one direction at the constant interval match. .