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JP2007184789

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DESCRIPTION JP2007184789
A horn capable of efficiently transmitting ultrasonic waves is provided. SOLUTION: The horn 1
widens the transmission range of ultrasonic waves transmitted from an ultrasonic transducer 2,
and comprises an opening 10 for exposing a part of the ultrasonic wave transmission surface in
the ultrasonic transducer 2. A substantially frusto-conical frusto-conical shape in which the
opening surface extends from the middle of the axial direction of the substantially cylindrical
cylindrical portion 10a and the bottom portion 11 to the transmission wavefront of the
transmission unit 20 and the inner peripheral surface is inclined. It formed in the form which
combined the part 10b. [Selected figure] Figure 1
ホーン
[0001]
The present invention relates to a horn that widens the transmission range of ultrasonic waves
transmitted from an ultrasonic transducer.
[0002]
Conventionally, an on-vehicle obstacle that detects the movement of an object by detecting
frequency components that change due to the Doppler effect by transmitting ultrasonic waves in
space and receiving a reflected wave from an object present in the space Ultrasonic sensors for
detection are known, for example as disclosed in US Pat.
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1
As shown in FIG. 2, an ultrasonic wave transmitter used in this type of ultrasonic sensor includes
an ultrasonic vibrator 2 for transmitting an ultrasonic wave and receiving a reflected wave from
an obstacle, and an ultrasonic vibration. And a horn 1 'for housing the element 2 and widening
the transmission range of the ultrasonic wave transmitted from the ultrasonic transducer 2.
[0003]
The ultrasonic transducer 2 is formed in a substantially cylindrical shape, and on one end face in
the axial direction, there is provided a transmission portion 20 composed of a substantially disklike piezoelectric element for transmitting ultrasonic waves, and on the other end face Two leads
21 are provided. The ultrasonic transducer 2 vibrates the transmission unit 20 by applying an
alternating voltage between the leads 21 to transmit an ultrasonic wave.
[0004]
The horn 1 'is formed in a bottomed cylindrical shape whose one end is open, and accommodates
the ultrasonic transducer 2 inside so that the transmission unit 20 is opposed to the bottom
portion 11 of the other end. An opening 10 ′ having a substantially circular shape in a plan
view and penetrating in the axial direction of the bottom 11 is provided substantially at the
center of the bottom 11. The opening 10 'is formed to have a diameter smaller than the diameter
of the transmission unit 20 of the ultrasonic transducer 2 as shown in FIG. 2 (b), and
transmission of the ultrasonic wave is performed by utilizing the diffraction of the sound wave. It
is expanding the range. JP 2001-238286 A
[0005]
Here, FIG. 2 (c) shows the result of measuring the sound pressure level of the ultrasonic wave at
a constant distance from the opening 10 'of the horn 1' in the above-mentioned conventional
example. In the figure, the vertical axis represents the sound pressure level of the ultrasonic
wave, and the horizontal axis represents the transmission angle of the ultrasonic wave when the
normal direction of the opening 10 'is 0 degree. As seen in the figure, it can be seen that the
sound pressure level of the ultrasonic wave is lowered in front of the opening 10 '. As described
above, in the above-described conventional example, the ultrasonic waves to be transmitted are
not efficiently output in front of the opening 10 ′ of the horn 1 ′, and the directivity of the
ultrasonic wave in front of the opening 10 ′ is deteriorated. there were.
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2
[0006]
The present invention has been made in view of the above points, and it is an object of the
present invention to provide a horn capable of efficiently transmitting ultrasonic waves.
[0007]
The invention according to claim 1 is a horn for expanding the transmission range of ultrasonic
waves transmitted from an ultrasonic transducer to achieve the above object, and at least one of
the transmission surfaces of ultrasonic waves in the ultrasonic transducer. An opening that
exposes the portion, wherein the opening is formed so as to narrow the opening along the
transmission direction of the ultrasonic wave, and at least a portion of the inner circumferential
surface is inclined along the transmission It is characterized by
[0008]
According to the invention of claim 1, the ultrasonic transducer has an opening for exposing at
least a part of the transmission surface of the ultrasonic wave, and the opening narrows along
the transmission direction of the ultrasonic wave. The ultrasonic wave transmitted from the wave
transmitting portion is collected and efficiently transmitted to the front of the opening, since at
least a part of the inner circumferential surface is inclined along the wave transmitting direction.
It can be waved, thus enhancing the directivity of the ultrasound in front of the opening.
[0009]
Hereinafter, embodiments of the present invention will be described with reference to the
drawings.
However, since the basic configuration in this embodiment is the same as that in the
conventional example, the same reference numerals are given to the common parts and the
description is omitted, and only the features that are the features of this embodiment will be
described in detail.
[0010]
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3
In the present embodiment, as shown in FIG. 1A, the opening 10 spreads from the middle of the
axial direction of the substantially cylindrical cylindrical portion 10a and the bottom 11 to the
transmission surface of the transmission unit 20. And it forms in the form which combined the
substantially frusto-conical-shaped frusto-conical part 10b in which an internal peripheral
surface inclines.
That is, the opening surface is formed so as to narrow along the transmission direction of the
ultrasonic wave from the transmission wavefront of the transmission unit 20, and the inner
peripheral surface of the opening 10 is the other edge from the peripheral edge of the opening
surface on the transmission unit 20 side. It inclines toward the rim of the opening face of.
Here, as in the conventional example, FIG. 1 (c) shows the result of measuring the sound pressure
level of the ultrasonic wave at a fixed distance from the opening 10 of the horn 1. In the figure,
the vertical axis represents the sound pressure level of the ultrasonic wave, and the horizontal
axis represents the transmission angle of the ultrasonic wave when the normal direction of the
opening 10 is 0 degree. It can be seen from the figure that the sound pressure level of the
ultrasonic wave in front of the opening 10 is not lowered, as compared with the result of the
conventional example (see FIG. 2C).
[0011]
The above result is obtained by increasing the exposed area of the transmission surface of the
transmission unit 20, narrowing the aperture surface along the transmission direction of the
ultrasonic wave, and setting the inner circumferential surface in the transmission direction. It is
presumed that the ultrasonic waves can be collected by tilting along the direction, and hence the
waves can be efficiently transmitted to the front of the opening 10 as well.
[0012]
In addition, by widening the opening surface on the side of the transmission unit 20, the contact
area between the transmission unit 20 and the horn 1 is reduced, thus reducing the interference
that occurs in a slight gap between the transmission unit 20 and the horn 1 It is speculated that
you can.
[0013]
It is a figure which shows the horn of embodiment of this invention, (a) is sectional drawing, (b) is
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4
the figure seen from the front of an opening part, (c) is a graph showing the directivity
characteristic of an ultrasonic wave.
It is a figure which shows the conventional horn, (a) is sectional drawing, (b) is the figure seen
from the front of an opening part, (c) is a graph showing the directivity characteristic of an
ultrasonic wave.
Explanation of sign
[0014]
1 horn 10 opening
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