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JP2000341785

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JP2000341785
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic sensor used mainly for transmitting and receiving ultrasonic waves in an on-vehicle
obstacle detector.
[0002]
2. Description of the Related Art Conventionally, an obstacle detector for detecting an obstacle
around a vehicle by transmitting and receiving ultrasonic waves has been provided. In this type
of obstacle detector, pulse ultrasonic waves (hereinafter referred to as ultrasonic pulse waves)
are intermittently transmitted, and the presence or absence of an obstacle within a
predetermined distance range is detected by the time difference until reception. Do. That is, a
reference signal having the configuration shown in FIG. 6 for setting the transmission interval of
ultrasonic pulse waves is generated by the transmission interval setting circuit 11, and from the
oscillation circuit 12 at the transmission interval set by the reference signal. Electric vibration of
a predetermined frequency is intermittently generated, and the ultrasonic sensor 10 is driven by
the electric vibration to transmit an ultrasonic pulse wave. If the obstacle C is present, the
ultrasonic wave sensor 10 receives a reflected wave to output an electric signal. The reception
signal output from the ultrasonic sensor 10 is input to the determination processing unit 15
through the detection gate circuit 14 after a signal corresponding to the generation period of the
reception signal is extracted by the reception circuit 13. The detection gate circuit 14 sets a
detection gate period after transmission of the ultrasonic pulse wave based on the reference
signal from the transmission interval setting circuit 11, and passes the signal only during the
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detection gate period. The determination processing unit 15 determines the presence or absence
of a signal component that has passed through the detection gate circuit 14, determines that an
obstacle C is present within a predetermined distance range when this signal component is
present, and outputs a detection signal. , Generate an alarm etc.
[0003]
The ultrasonic sensor 10 is attached to a bumper or the like of the vehicle to monitor the
periphery of the vehicle. Therefore, in order to reliably detect an obstacle present around the
vehicle, the directivity of the ultrasonic sensor 10 is set to be broad in the lateral direction along
the road surface, and the directivity is sharp in the longitudinal direction so as not to detect the
road surface. It is necessary to set it.
[0004]
Then, the ultrasonic sensor 10 of the shape shown in FIG. 7 is used. In the ultrasonic sensor 10,
an ultrasonic transducer 1 whose front surface (left surface in FIG. 7B) is a transmission /
reception wavefront is attached to a horn 3 via a vibration isolation material 2. The horn 3 is
formed with an opening 4 in which the cross section orthogonal to the transmission / reception
direction of the ultrasonic transducer 1 (the direction orthogonal to the transmission / reception
wavefront of the ultrasonic transducer 1) has an elliptical shape whose longitudinal axis is the
longitudinal direction. It is done. The directivity of the ultrasonic sensor 10 is set by the shape of
the opening 4. However, let the horizontal direction and the vertical direction be the A-A
'direction and the B-B' direction shown in FIG. 7A, respectively.
[0005]
By the way, the half-value angle (beam width of the part which is -6 dB from the peak sound
pressure) showing the sharpness of the directivity of the ultrasonic wave means that the sound
source is a circular sound source and the sound source diameter is d and the wavelength of the
ultrasonic wave is λ. Then, in general, θ = Sin−1 (0.71 λ / d), and as the sound source
diameter d increases, the half value angle θ decreases and the directivity becomes sharp.
Therefore, the diameter d1 of the opening 4 in the longitudinal direction is larger than the
diameter d2 of the opening in the lateral direction. By this configuration, the directivity of the
ultrasonic sensor 10 is as shown in FIG. That is, since the vertical opening diameter d1 of the
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opening 4 is larger than the horizontal opening diameter d2, as shown in FIG. 8A, the directivity
in the horizontal direction on the line AA 'is set to be broad, As shown in FIG. 8B, the directivity
in the vertical direction on the line B-B 'is set sharper than in the horizontal direction.
[0006]
However, in the ultrasonic sensor 10 shown in FIG. 7, in order to obtain the directivity shown in
FIG. 8, the diameter d1 of the longitudinal direction of the opening 4 is made equal to the
diameter d2 of the lateral direction. Since the size of the horn 3 is larger than that of the
ultrasonic sensor 10, the size of the horn 3 is determined depending on the aperture diameter d1
in the vertical direction, and the ultrasonic sensor 10 is difficult to miniaturize, and an excellent
appearance can not be obtained. In addition, since the opening 4 has an elliptical cross section
orthogonal to the transmission / reception direction of the ultrasonic transducer 1 with the
longitudinal axis as the long axis, water droplets flowing into the opening 4 while the vehicle is
traveling is the opening It becomes easy to gather near the center of the lower part of 4 and to
accumulate, and a malfunction which detects a water droplet accumulated in the lower part of
opening 4 as an obstacle becomes easy to occur.
[0007]
The present invention has been made in view of the above-mentioned problems, and an object
thereof is to provide an ultrasonic sensor which is apparently reduced in size and in which the
malfunction caused by the accumulation of water droplets in the opening of the horn is
prevented. .
[0008]
According to the first aspect of the present invention, there is provided an ultrasonic transducer
for transmitting and receiving ultrasonic waves, and an ultrasonic vibration so as to set
directivity of ultrasonic waves transmitted from the ultrasonic transducer. And a horn having an
opening for exposing at least a part of the transmission / reception wavefront of the child,
wherein the width of the opening in the longitudinal direction is set smaller than the width of the
opening in the lateral direction, and the inner peripheral surface of the opening Among them, a
pair of lateral surfaces which are both sides in the longitudinal direction are planar and the
distance between them is constant.
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According to this configuration, the width of the opening in the longitudinal direction is smaller
than the width of the width in the lateral direction, and a pair of lateral surfaces on both sides in
the longitudinal direction of the inner peripheral surface of the opening are planar. Since the
distance is constant, broad directivity can be obtained by using the directivity of the ultrasonic
transducer not attached to the horn in the lateral direction, and the width between the planes in
the longitudinal direction is determined from the lateral direction. By setting it too small, it
becomes possible to control the directivity to be sharper than in the lateral direction. That is, if
the opening width of the opening is set in the horizontal direction so as to obtain directivity
similar to that of the conventional configuration, the size in the longitudinal direction is smaller
than that of the conventional configuration, and the size of the horn By making the width of the
opening in the lateral direction, it is possible to miniaturize the appearance of the ultrasonic
sensor more than the conventional configuration. In addition, since the lateral surface of the
opening is flat, water droplets flowing into the opening propagate along the lower lateral surface
without collecting at the center of the lower part of the opening and exit from the opening. It is
possible to prevent a malfunction such as detecting a water droplet accumulated in the lower
part as an obstacle.
[0009]
The invention of claim 2 relates to the invention according to claim 1, wherein at least a part of a
pair of vertical surfaces which are both sides in the horizontal direction among the inner
peripheral surfaces of the opening portion is the transmission / reception wavefront of the
ultrasonic transducer. A tapered surface is formed to be inclined so as to extend the distance
toward the tip of the horn. According to this configuration, by forming the tapered surface on the
vertical surface of the opening, the horn length which is the length in the transmission /
reception direction of the ultrasonic transducer can be made shorter than in the case where the
tapered surface is not provided. Further, by providing the tapered surface, the water droplets
flowing into the opening are guided by the tapered surface after passing through the lower side
surface and then guided out of the opening, so that the water droplets are less likely to be
accumulated in the lower part of the opening In addition, the appearance of the ultrasonic sensor
mounted on a bumper of a vehicle can be improved.
[0010]
According to a third aspect of the present invention, in the second aspect of the present
invention, each of the tapered surfaces is formed into a curved surface so as to be convex toward
the inside of the opening.
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[0011]
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be
described below with reference to the drawings.
[0012]
(Embodiment 1) As shown in FIG. 1, in the ultrasonic sensor 10 according to the present
embodiment, ultrasonic vibration in which the front surface (left surface in FIG. 1 (b)) becomes a
transmitting / receiving wavefront as in the conventional example shown in FIG. The child 1 is
attached to the horn 3 via the vibration-proof material 2.
[0013]
As shown in FIGS. 1 (b) and 1 (c), the ultrasonic transducer 1 has a substantially cylindrical
shape, the vibration damping material 2 has a cylindrical shape, and the ultrasonic transducer 1
is press-fitted.
The horn 3 has a tubular shape having a wall 3a on the front side, and the ultrasonic transducer
1 press-fitted to the vibration-proof material 2 is press-fitted from the rear side.
[0014]
An opening 4 is formed in the wall 3 a, and the opening 4 is smaller than the outer periphery of
the vibration-proof material 2.
Thereby, when the ultrasonic transducer 1 press-fit into the vibration-proof material 2 is press-fit
into the horn 3, the front surface of the vibration-proof material 2 abuts against the rear surface
of the wall 3a to position the ultrasonic transducer 1 Ru.
Thus, the ultrasonic transducer 1 is attached to the horn 3 via the vibration-proof material 2, and
the front surface of the ultrasonic transducer 1 and a part of the vibration-proof material 2 are
exposed from the opening 4.
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[0015]
In the present embodiment, as shown in FIG. 1A, the opening 4 is formed in a rectangular shape
whose cross section orthogonal to the transmission / reception direction of the ultrasonic
transducer 1 is long in the lateral direction, and the inner peripheral surface of the opening 4 On
both sides in the longitudinal direction and the lateral direction, a planar lateral surface 4a and a
longitudinal surface 4b are respectively formed. However, let the horizontal direction and the
vertical direction be respectively the A-A 'direction and the B-B' direction shown in FIG.
[0016]
The vertical opening width D1 of the opening 4 is formed to be substantially equal to the
diameter of the ultrasonic transducer 1, and the horizontal opening width D2 of the opening 4 is
larger than the vertical opening width D1 and the ultrasonic wave The diameter is larger than the
diameter of the vibrator 1. Further, in the horizontal surface 4a and the vertical surface 4b, the
vertical opening width D1 and the horizontal opening width D2 of the opening 4 are constant.
[0017]
In the present embodiment, by using the directivity of the ultrasonic transducer 1 in a state
where the opening 4 is formed in the above-described shape and not attached to the horn 3,
transmission is performed from the ultrasonic transducer 1 through the horn 3 The directivity of
the ultrasonic wave is set as shown in FIG. That is, as shown in FIG. 2A, the directivity in the
horizontal direction on the A-A 'line is set broad, and as shown in FIG. 2B, the directivity in the
vertical direction on the B-B' line is horizontal The directivity is set sharper than the direction,
and the same directivity as that of the conventional example shown in FIG. 8 is obtained.
[0018]
Moreover, the directivity of the ultrasonic wave in the lateral direction is controlled so as to
utilize the broad directivity of the ultrasonic transducer 1 and the directivity in the longitudinal
direction is made sharper than the transverse direction by using the horizontal surface 4a which
is a plane. doing. Therefore, in order to set the directivity in the lateral direction to the same level
as the conventional example, the lateral opening width D2 of the opening 4 is approximately the
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same as the lateral opening diameter d2 of the opening 4 in the conventional example shown in
FIG. If it is set to, the opening width D1 in the longitudinal direction can be made smaller than
that of the prior art. That is, by matching the size of the horn 3 to the opening width D2 in the
lateral direction, the ultrasonic sensor 10 can be downsized in size compared to the conventional
example.
[0019]
In addition, even if water droplets flow into the opening 4 while the vehicle is traveling, the
horizontal surface 4a is formed in a flat shape, so the water droplets do not collect at the center
of the lower horizontal surface 4a. After being transmitted and flowing to the left and right sides
of the opening 4, the light exits from the opening 4. As a result, it is possible to prevent a
malfunction such as detecting a water droplet accumulated in the lower part of the opening 4 as
an obstacle, as compared with the conventional example shown in FIG.
[0020]
Second Embodiment As shown in FIG. 3, in the second embodiment, tapered surfaces 4c are
formed on both sides in the lateral direction of the inner peripheral surface of the opening 4
instead of the vertical surface 4b of the first embodiment. The opening 4 is configured by 4 a and
the tapered surface 4 c. The tapered surface 4c is curved along the circumferential direction of
the front surface of the ultrasonic transducer 1 as shown in FIG. 3 (a), and from the front surface
of the ultrasonic transducer 1 as shown in FIG. 3 (c) It is in the form of a flat surface inclined so
as to increase the distance to each other toward the front end side. Also in the present
embodiment, the directivity characteristics as shown in FIG. 4 can be obtained as in the first
embodiment. Here, FIG. 4A shows directivity in the horizontal direction, and FIG. 4B shows
directivity in the vertical direction.
[0021]
In the present embodiment, since the opening width of the opening 4 of the horn 3 is set as
described above and the tapered surface 4 c is formed in the opening 4, the horn has a directivity
characteristic similar to that of the conventional configuration. When 3 is formed, as shown in
FIG. 3B, the horn length L, which is the length in the transmission / reception direction of the
ultrasonic transducer 1 on the inner peripheral surface of the opening 4, is the horn length L 'of
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the conventional configuration. It can be shorter than Incidentally, while the horn length L 'is 4
mm in the conventional configuration, the horn length L is 2 mm in the present embodiment.
[0022]
Further, by providing the tapered surface 4c, the water droplets having flowed into the opening 4
are guided by the tapered surface after passing through the lower side surface 4a and then exit
from the opening 4 Water droplets are less likely to be accumulated in the lower part of 4, and
the appearance when the ultrasonic sensor 10 is attached to a bumper or the like of a vehicle can
be improved.
[0023]
As shown in FIG. 5, the same effect can be obtained even when the tapered surface 4 c is a
curved surface (see FIG. 5 (c)) that is curved to be convex inside the opening 4.
In addition, it is possible to shorten the horn length L even if only a part of the vertical surface 4b
of the first embodiment is used as the tapered surface 4c. Furthermore, the horn 3 may be a
processed product or a molded product, and the horn 3 and the vibration damping material 2
may be integrated into one member.
[0024]
According to the first aspect of the present invention, there is provided an ultrasonic transducer
for transmitting and receiving ultrasonic waves, and a transmitting and receiving wavefront of
the ultrasonic transducer so as to set directivity of ultrasonic waves transmitted from the
ultrasonic transducer. And a horn having an opening for exposing at least a part of the opening,
and the width of the opening in the longitudinal direction is set smaller than the width of the
opening in the lateral direction. And the width of the opening in the longitudinal direction is
smaller than the width of the opening in the lateral direction, and the inner peripheral surface of
the opening is in the longitudinal direction. Since a pair of lateral surfaces on both sides are flat
and the distance between them is constant, broad directivity can be obtained by using the
directivity of the ultrasonic transducer in a state not attached to the horn in the lateral direction.
Set the opening width between planes smaller in the vertical direction than in the horizontal
direction. In making it possible to control so that sharper than the lateral directional. That is, if
the opening width of the opening is set in the horizontal direction so as to obtain directivity
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similar to that of the conventional configuration, the size in the longitudinal direction is smaller
than that of the conventional configuration, and the size of the horn By adjusting the width of the
opening to the width of the opening in the lateral direction, the ultrasonic sensor can be made
smaller in size than the conventional configuration. In addition, since the lateral surface of the
opening is flat, water droplets flowing into the opening propagate along the lower lateral surface
without collecting at the center of the lower part of the opening and exit from the opening. There
is an advantage that it is possible to prevent a malfunction such as detecting a water droplet
accumulated in the lower part as an obstacle.
[0025]
The invention according to claim 2 is the invention according to claim 1, wherein at least a part
of the pair of vertical surfaces on both sides in the lateral direction among the inner peripheral
surfaces of the opening is the transmission / reception wavefront of the ultrasonic transducer to
the tip of the horn. A tapered surface is formed to be inclined so as to widen the distance toward
the side, and by forming a tapered surface on the vertical surface of the opening, the length of
the ultrasonic transducer in the transmission / reception direction is obtained. A certain horn
length can be made shorter than the case where no tapered surface is provided. Further, by
providing the tapered surface, the water droplets flowing into the opening are guided by the
tapered surface after passing through the lower side surface and then guided out of the opening,
so that the water droplets are less likely to be accumulated in the lower part of the opening In
addition, there is an advantage that the appearance when the ultrasonic sensor is attached to a
bumper of a vehicle is improved.
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