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DESCRIPTION JP2007306043

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DESCRIPTION JP2007306043
PROBLEM TO BE SOLVED: To realize an ultrasonic sensor capable of efficiently receiving an
ultrasonic wave and protecting a receiving element. SOLUTION: An ultrasonic wave U reflected
by an obstacle M and incident to the inside of a waveguide 33 from a first opening 33b is
reflected in a direction toward a plurality of receiving elements 10 at a reflecting surface 33a.
Since the sound wave U is directly transmitted to each receiving element 10 without passing
through other members, the attenuation of ultrasonic waves can be reduced. In addition, since
the attenuation of the ultrasonic wave U due to multiple reflection or the like in the waveguide
33 can be reduced, the sensitivity of the ultrasonic sensor 1 can be improved. Further, since the
second opening 33 c is disposed at a position where it can not be visually recognized from the
first opening 33 b, even when foreign matter comes in and enters the inside of the waveguide 33
from the first opening 33 b, Since there is no possibility of direct collision with the receiving
element 10, the receiving element 10 can be protected. [Selected figure] Figure 2
Ultrasonic sensor
[0001]
The present invention relates to an ultrasonic sensor that receives and detects an ultrasonic wave
reflected by an object to be detected by a receiving element.
[0002]
In recent years, as this type of ultrasonic sensor, for example, one mounted on a car (vehicle) is
known.
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1
The ultrasonic sensor transmits ultrasonic waves from the transmitting means, and receives
ultrasonic waves reflected by the detected object by the receiving means, thereby measuring the
direction in which the object is located around the car and the distance to the object Make
measurements etc. As described above, development of a technology that is useful for safe
driving is underway by monitoring the surroundings of a vehicle by using an ultrasonic sensor.
For example, an ultrasonic sensor is mounted at the rear of a car, and a back sonar is used to
detect ultrasonic waves reflected by people or obstacles present behind the car and detect the
ultrasonic waves by using the ultrasonic sensor. Automatic parking support systems have been
put to practical use that support parking at the back by avoiding collisions with such devices.
Furthermore, as a receiving element of an ultrasonic sensor, an ultrasonic sensor in which a
vibrating portion made of a piezoelectric thin film is formed on a thin film portion formed as a
thin portion of a substrate using MEMS (Micro Electro Mechanical System) technology The
receiving element of is noted.
[0003]
Here, in the case where the receiving element of the ultrasonic sensor is exposed to the outside
and mounted on a vehicle, if water droplets or dust adhere to the surface of the receiving
element, the distance to the object to be detected can not be measured accurately. In addition,
there is a risk of being destroyed by the load of external force such as a pebble collision.
Therefore, as an ultrasonic sensor provided with a protective structure for preventing damage
due to contamination of the receiving element or external load, for example, in Patent Document
1, the receiving element is internally mounted in an aluminum case so as not to be exposed to the
outside, There is disclosed an ultrasonic sensor in which a piezoelectric vibration detection
element for detecting an ultrasonic wave is directly attached to a waveguide also serving as a
diaphragm, and the ultrasonic wave is received by the vibration of the waveguide. Japanese
Patent Laid-Open No. 2002-58097
[0004]
However, in an ultrasonic sensor using a MEMS-type receiving element having a vibrating part
such as a piezoelectric or capacitive ultrasonic sensor and detecting ultrasonic waves by the
vibration of the vibrating part, the receiving element is directly attached to the metal case In the
pasting structure, sufficient vibration can not be obtained. Furthermore, an ultrasonic sensor
using a MEMS receiving element has a problem that it is easily damaged if it is directly attached
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2
to a metal case because the mechanical strength of the piezoelectric thin film of the receiving
element is low due to its structure. And when a space is provided between a receiving element
and a metal case without attaching a receiving element to a metal case, there existed a problem
that an ultrasonic wave can not be received efficiently.
[0005]
Therefore, an object of the present invention is to realize an ultrasonic sensor capable of
efficiently receiving an ultrasonic wave and protecting a receiving element.
[0006]
According to the present invention, in order to achieve the above object, according to the
invention as set forth in claim 1, a vibration unit capable of receiving an ultrasonic wave by
transmitting and vibrating the ultrasonic wave is provided, and An ultrasonic sensor comprising:
a plurality of receiving elements for detecting the object to be detected by a sound wave; and a
waveguide formed to be capable of transmitting an ultrasonic wave to the plurality of receiving
elements, wherein the waveguide is An opening is formed on the side of the object to be detected,
and is disposed at a first opening where the ultrasonic wave reflected by the object to be
detected is incident, and a position not visible from the first opening, and each of the plurality of
receiving elements A vibrating portion, a second opening portion directed in the receiving
direction of the ultrasonic wave, and a reflecting surface for reflecting the ultrasonic wave
incident from the first opening portion in the direction toward the plurality of receiving elements
Use the technical means to prepare.
[0007]
According to the first aspect of the present invention, the ultrasonic wave reflected by the object
to be detected and incident to the inside of the waveguide from the first opening is reflected in
the direction toward the plurality of receiving elements on the reflecting surface. Since the
ultrasonic waves are directly transmitted to the receiving element without passing air to the
medium, the attenuation of the ultrasonic waves can be reduced.
In addition, since the attenuation of ultrasonic waves due to multiple reflection or the like inside
the waveguide can be reduced as compared with the case where no reflective surface is formed,
the sensitivity of the ultrasonic sensor can be improved.
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In addition, since the second opening is disposed at a position not visible from the first opening,
for example, foreign matter such as pebbles or water droplets fly toward the waveguide and the
waveguide from the first opening Even in the case of intrusion into the inside, the receiving
element can be protected because there is no possibility of direct collision with the receiving
element. That is, it is possible to realize an ultrasonic sensor capable of receiving ultrasonic
waves efficiently and protecting the receiving element. Further, by obtaining the time difference
and the phase difference of the ultrasonic waves received by the plurality of receiving elements,
not only the distance to the object to be detected but also the position of the object to be
detected can be measured based on the respective differences. In addition, it is not necessary to
prepare a waveguide for each of a plurality of receiving elements, and it can be integrated into
one waveguide, so the size of the waveguide can be reduced, and the ultrasonic sensor can be
miniaturized. can do.
[0008]
In the invention according to claim 2, in the ultrasonic sensor according to claim 1, the ultrasonic
wave incident from the first opening is directly reflected by the reflection surface, and the
ultrasonic wave reflected by the reflection surface is A technical means is used in which the first
opening and the respective vibrating parts are arranged with respect to the reflecting surface so
as to be directly transmitted to the respective vibrating parts.
[0009]
According to the second aspect of the present invention, an ultrasonic wave having a large sound
pressure that is directly incident on the reflective surface from the first opening can be
transmitted directly from the reflective surface to the receiving element of the ultrasonic sensor.
The attenuation of ultrasonic waves can be reduced, and the sensitivity of the ultrasonic sensor
can be improved.
[0010]
In the invention according to claim 3, in the ultrasonic sensor according to claim 1 or 2, the
surface of the reflecting surface is formed of a material having a higher reflectance of ultrasonic
waves than the inner wall surface of the waveguide. Technical means that the reflecting member
is formed.
[0011]
According to the third aspect of the present invention, the reflective member is formed on the
surface of the reflective surface because the reflective member is formed of a material having a
higher reflectance of ultrasonic waves than the inner wall surface of the waveguide. Since the
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reflection efficiency of the ultrasonic wave on the reflection surface is improved as compared
with the case where no reflection is made, the sensitivity of the ultrasonic sensor can be further
improved.
[0012]
In the invention according to claim 4, in the ultrasonic sensor according to any one of claims 1 to
3, of the inner wall surface of the waveguide, the surface other than the reflection surface is
more than the reflection surface. Also, the technical means is used in which an absorbing
member formed of a material having a high absorption rate of ultrasonic waves is formed.
[0013]
According to the fourth aspect of the present invention, the absorbing member formed of a
material having a higher absorptivity of ultrasonic waves than the reflecting surface is formed on
the surface of the inner wall surface of the waveguide excluding the reflecting surface. Since the
ultrasonic wave that is reflected by the inner wall surface of the waveguide and becomes noise
can be reduced, the sensitivity of the ultrasonic sensor can be further improved.
[0014]
In the invention as set forth in claim 5, in the ultrasonic sensor according to any one of claims 1
to 4, the first opening may be formed at a predetermined position inside the waveguide. A
technical means is used in which the cross-sectional area is formed so as to increase as it
approaches the end of the opening closer to the object to be detected.
[0015]
According to the fifth aspect of the present invention, since the ultrasonic waves to be received
can be collected at the first opening, the sound pressure of the ultrasonic waves to be received
can be increased, and the sensitivity of the ultrasonic sensor can be increased. It can be
improved.
[0016]
In the invention according to claim 6, in the ultrasonic sensor according to any one of claims 1 to
4, the first opening is a portion of the first opening from a predetermined position inside the
waveguide. A technical means is used in which the cross-sectional area is formed to be smaller as
it approaches the end of the opening closer to the object to be detected.
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[0017]
According to the sixth aspect of the present invention, the cross-sectional area of the waveguide
is increased to efficiently transmit the ultrasonic waves, and the first opening is formed to be
narrow. It is possible to reduce the intrusion of foreign matter and the like.
[0018]
In the invention according to claim 7, in the ultrasonic sensor according to any one of claims 1 to
6, the first opening prevents the entry of foreign matter into the inside of the waveguide. And,
the technical means of being covered by the transmission member which can transmit an
ultrasonic wave to the waveguide is used.
[0019]
According to the seventh aspect of the present invention, since the first opening is covered by the
transmission member, it is possible to reliably block the entry of a liquid such as a small foreign
matter or a water droplet, so that the ultrasonic sensor can be more reliably. Can be protected.
[0020]
In the invention according to claim 8, in the ultrasonic sensor according to any one of claims 1 to
7, a transmission element capable of transmitting an ultrasonic wave toward the object in the
waveguide. Use the technical means of
[0021]
According to the eighth aspect of the present invention, transmission and reception of ultrasonic
waves become possible by arranging a transmission element capable of transmitting ultrasonic
waves toward the detection target in addition to the reception elements in the waveguide.
The ultrasonic wave transmitted from the transmission element is, for example, reflected by the
reflection surface in the direction of the detection object.
Thereby, the ultrasonic sensor capable of transmission and reception can be mounted without
impairing the design of the object on which the ultrasonic sensor is mounted.
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[0022]
In the invention according to claim 9, in the ultrasonic sensor according to any one of claims 1 to
8, a technical means of being attached to an object used outdoors is used.
[0023]
In the invention according to claim 10, in the ultrasonic sensor according to claim 9, the
technical means is used that the object is a vehicle or a robot.
[0024]
According to the ninth aspect of the present invention, the ultrasonic sensor can be used by
attaching to an object used outdoors.
In particular, as described in claim 10, it can be suitably used by being mounted on a vehicle or a
robot.
[0025]
An embodiment of a waveguide of an ultrasonic sensor according to the present invention will be
described with reference to the drawings.
Here, the case where an ultrasonic sensor is mounted on a vehicle and used as an obstacle sensor
will be described as an example.
FIG. 1 is an explanatory view of a receiving element of an ultrasonic sensor.
FIG. 1A is a plan view of the receiving element, and FIG. 1B is a cross-sectional view of FIG. 1A
taken along the line A-A.
FIG. 2 is an explanatory view of the ultrasonic sensor according to the first embodiment.
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2 (A) is a longitudinal sectional view of the ultrasonic sensor, FIG. 2 (B) is a plan view of FIG. 2 (A)
seen from the direction A, and FIG. 2 (C) is a view It is the plane explanatory view which looked
at 2 (A) from the B direction.
In FIG. 2, the right side in the drawing shows the outside of the vehicle.
FIG. 3 is a longitudinal sectional view showing a modified example of the reflecting surface.
FIG. 4 is a vertical cross-sectional explanatory view showing a modification of the first opening.
FIG. 5 is a longitudinal cross-sectional explanatory view of an ultrasonic sensor provided with a
reflecting member that reflects ultrasonic waves on the reflecting surface.
FIG. 6 is an explanatory view of a vertical cross section in which an absorbing member is
provided on a surface of the inner wall surface of the waveguide excluding the reflective surface.
FIG. 7 is an explanatory vertical cross-sectional view showing a modification of the arrangement
of the first opening, the second opening, and the reflecting surface.
In each of the drawings, a part is enlarged for the purpose of explanation. Moreover, in FIG. 2
and subsequent figures, the structure of the receiving element is simplified and shown.
[0026]
(Structure of Receiving Element of Ultrasonic Wave) First, the structure of the receiving element
provided in the ultrasonic sensor will be described. As shown in FIGS. 1A and 1B, the receiving
element 10 is formed using a square semiconductor substrate 11 having an SOI (Silicon On
Insulator) structure. The semiconductor substrate 11 is formed by laminating a first insulating
film 11b, a silicon active layer 11c, and a second insulating film 11d in this order on the upper
surface 11m of the support member 11a made of silicon. In the central portion of the
semiconductor substrate 11, the central portions of the support member 11a and the first
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8
insulating film 11b are removed in a square shape by the MEMS technology. Thereby, the
supporting member 11a is formed in a frame shape in which the central portion is hollowed out
in a square pole, and the remaining silicon active layer 11c and the second insulating film 11d
are each formed in a rectangular thin film shape.
[0027]
The piezoelectric vibrator 12 is formed on the second insulating film 11 d so as to cover the thin
film-formed portion. The piezoelectric vibrator 12 is formed, for example, by sandwiching a
piezoelectric thin film 12 a made of lead zirconate titanate (PZT) with the lower electrode 13 and
the upper electrode 14. The lower surface electrode 13 and the upper surface electrode 14 are
composed of a quadrangular portion sandwiching the piezoelectric thin film 12 a and electrode
pads 13 a and 14 a for extracting a potential formed in the vicinity of a corner of the
semiconductor substrate 11. Further, a third insulating film 15 is formed on the surface of the
upper surface electrode 14. Of the portion in which the silicon active layer 11c, the second
insulating film 11d, the piezoelectric vibrator 12, the lower surface electrode 13, the upper
surface electrode 14 and the third insulating film 15 are stacked, the frame-like opening formed
in the support member 11a The corresponding portion forms the vibrating portion 16 whose end
is supported by the support member 11a.
[0028]
The vibrating unit 16 has a predetermined resonance frequency, receives an ultrasonic wave
reflected by the detection object and transmitted to the receiving element 10, and resonates. The
displacement of the vibrating portion 16 caused by the resonance is converted into a voltage
signal by the piezoelectric vibrator 12 to detect an ultrasonic wave. As described above, in the
receiving element 10 manufactured by using the MEMS technology, since the vibrating portion
16 is supported by the support member 11a, the region for contacting the vibrating portion 16
and restraining the vibration is reduced. The displacement of the vibration unit 16 can be
increased, and the vibration reception sensitivity can be enhanced. For this reason, since the
receiving sensitivity of an ultrasonic wave is high, it is suitable as a receiving element.
[0029]
(Structure of Ultrasonic Sensor) As shown in FIG. 2A, a waveguide 33 for transmitting an
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ultrasonic wave to the receiving element 10 is formed in a shape in which a tubular member
having a rectangular longitudinal cross section is bent at substantially a right angle The first
opening 33b has an opening formed on the side of the obstacle M, which is an object to be
detected, and the ultrasonic wave U reflected by the obstacle M is incident, and is disposed at a
position invisible from the first opening Each vibration portion 16 of the plurality of receiving
elements 10 directs the ultrasonic waves incident from the first opening 33b to the respective
receiving elements 10 with the second opening 33c arranged in the receiving direction of the
ultrasonic waves U. And a reflective surface 33a that reflects in a direction. In the waveguide 33,
the first opening 33b is attached to the outside of the body 52 at the attachment portion formed
in the body 52 directly below the bumper with the end of the first opening 33b exposed to the
outside of the vehicle. It is attached to be perpendicular to the surface.
[0030]
As shown in FIG. 2 (B), in the ultrasonic sensor 1 of the present embodiment, four receiving
elements 10 are arranged in an array in which two each are arranged in parallel in the vertical
and horizontal directions in the second opening 33c. . Here, each vibrating portion 16 is attached
so as to be substantially vertical in the receiving direction of the ultrasonic wave U, and the
distance between the central portions of the vibrating portions 16 of the respective receiving
elements 10 adjacent to each other is It is arranged to be equal to an integral multiple of the half
wavelength of the sound wave U.
[0031]
The reflecting surface 33a is formed on the inner wall surface of the bending portion 33d at an
angle of 45 ° with respect to the incident direction of the ultrasonic wave U, and as shown in
FIG. 2C, from the first opening 33b The reflective surface 33a is only visible, and the second
opening 33c can not be viewed.
[0032]
The waveguide 33 is a structural member that holds the receiving element 10, and is preferably
made of a hard material in order to improve the reflection efficiency of the ultrasonic waves U on
the reflection surface 33a.
Therefore, as a material which comprises the waveguide 33, various metal materials, such as
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stainless steel and aluminum alloy, are preferable. Further, various synthetic resins, glass,
ceramics and the like can also be used.
[0033]
Here, since the sound pressure of the ultrasonic wave is proportional to the cross-sectional area
of the transmission path, the opening area of the first opening 33 b is the area of the vibrating
portion 16 in order to receive the ultrasonic wave with sufficient signal strength. It is preferable
to set it as the above.
[0034]
(Transmission of Ultrasonic Wave) The ultrasonic wave U transmitted from a transmitting
element (not shown) and reflected by the obstacle M is incident on the inside of the waveguide
33 from the first opening 33 b and reflected by the reflecting surface 33 a The light reaches the
receiving element 10 according to the incident position in the first opening 33 b later, and is
detected by the vibration unit 16.
[0035]
For example, as shown in FIG. 2A, the ultrasonic wave U incident on the first opening from the
upper position in the drawing is reflected at the upper left portion of the reflecting surface 33a in
the drawing, and is disposed on the left side. It is detected by the element 10.
Further, the ultrasonic wave U incident on the first opening from the lower position in the
drawing is reflected at the lower right part of the reflecting surface 33a in the drawing and
detected by the receiving element 10 disposed on the right.
[0036]
The vibration of the ultrasonic wave is transmitted to the vibration unit 16, and when the
vibration unit 16 vibrates, a voltage signal is output from the piezoelectric vibrator 12 (FIG. 1) to
a circuit element not shown.
The circuit converts the voltage signal output from the piezoelectric vibrator 12 into a signal that
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11
can be processed by the ECU and outputs the signal to the ECU, and the ECU performs
predetermined arithmetic processing based on the input signal.
[0037]
As described above, when a plurality of receiving elements 10 are used, the time difference and
the phase difference of the ultrasonic waves received by each receiving element 10 are obtained,
and based on the respective differences, not only the distance to the obstacle M but also the
obstacle The position of object M can also be measured. In addition, it is not necessary to prepare
waveguides 33 for a plurality of receiving elements 10, and it can be integrated into one
waveguide 33. Therefore, the size of the waveguides 33 can be reduced. The acoustic wave
sensor 1 can be miniaturized. Here, as in the present embodiment, if the distance d between the
central portions of the vibrating portions 16 of the respective receiving elements 10 adjacent to
each other is arranged to be equal to an integral multiple of the half wavelength of the ultrasonic
wave U, the received super Since the time difference can also be detected from the phase
difference of the sound waves, the time difference of the received ultrasonic waves can be
accurately detected. Therefore, the measurement accuracy of the distance to the obstacle M and
the position can be improved.
[0038]
When the ultrasonic sensor 1 configured as described above is used, the ultrasonic waves U
reflected by the obstacle M and incident on the inside of the waveguide 33 from the first opening
33 b are received by the reflection surface 33 a by a plurality of receiving elements Since the
ultrasonic waves U are directly transmitted to the respective receiving elements 10 without
passing air to the medium because they are reflected in the direction toward 10, the attenuation
of the ultrasonic waves can be reduced. In addition, since the attenuation of the ultrasonic wave
U due to multiple reflection or the like in the waveguide 33 can be reduced compared to the case
where the reflecting surface 33 a is not formed, the sensitivity of the ultrasonic sensor 1 can be
improved. . Furthermore, if the ultrasonic waves U reflected by the reflection surface 33 a are
arranged to be directly transmitted to the vibrating portion 16, the displacement of the vibrating
portion 16 can be increased, so that the detection signal by the receiving element 10 becomes
large. The sensitivity of the ultrasonic sensor 1 can be improved.
[0039]
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In addition, since the second opening 33 c is disposed at a position not visible from the first
opening 33 b, for example, foreign matter such as pebbles or water droplets fly toward the
waveguide 33 and the first opening Even when the portion 33 b enters the inside of the
waveguide 33, there is no possibility of direct collision with the receiving element 10, so the
receiving element 10 can be protected. That is, the ultrasonic sensor 1 capable of receiving the
ultrasonic waves U efficiently and protecting the receiving element 10 can be realized.
[0040]
The number of receiving elements 10 is an example, and is not limited to four. Also, the
arrangement is not limited to two each. Alternatively, a chip in which a plurality of receiving
elements 10 are integrally formed may be used. As the receiving element 10, various types of
sensors can be used. For example, a capacitive vibration detection element that detects an
ultrasonic wave by a change in capacitance between electrodes can also be used. Also, instead of
the receiving element 10, an element capable of transmitting and receiving can be used.
[0041]
The waveguide 33 is not limited to a tubular of square cross section, and may be cylindrical, for
example. In addition, the arrangement interval of the receiving elements 10 can be changed by
adjusting the reflection direction of the ultrasonic waves U according to the shape, the angle, and
the like of the reflection surface 33 a.
[0042]
(Modification 1) The reflection surface 33a may be formed into a curved surface instead of a flat
surface as long as it can reflect the ultrasonic wave incident from the first opening 33b in the
direction toward each receiving element 10. For example, as shown in FIG. 3, you may form in
circular arc shape.
[0043]
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(Modification 2) As shown in FIG. 4A, the cross-sectional area of the first opening 33b increases
from the inside of the waveguide 33 toward the end on the obstacle M side of the first opening
33b. It may be formed in the following shape. By using this configuration, since the ultrasonic
waves U can be collected at the first opening 33b, the sound pressure of the ultrasonic waves U
can be increased, and the sensitivity of the ultrasonic sensor 1 can be improved. . As shown in
FIG. 4B, the first opening 33b is formed in such a shape that the cross-sectional area decreases
from the inside of the waveguide 33 toward the end on the obstacle M side of the first opening
33b. May be When this configuration is used, since the first opening 33b is narrowed, it is
possible to reduce the intrusion of foreign matter and the like from the outside of the vehicle.
Further, in the case where the ultrasonic sensor 1 is provided with a transmittable transmittable
element, since ultrasonic waves can be collected at the first opening 33b at the time of
transmission of ultrasonic waves, ultrasonic waves can be transmitted. Sound pressure can be
increased.
[0044]
(Modification 3) As shown in FIG. 5, for example, plating may be performed on the reflection
surface 33 a to form the reflection member 35 having a higher reflectance of ultrasonic waves
than the inner wall surface of the waveguide 33. When this configuration is used, the reflection
efficiency of the ultrasonic waves on the reflection surface is improved, so that the sensitivity of
the receiving element 10 can be further improved. Here, the reflecting member 35 may be
formed by sticking a hard material such as a metal plate, glass, or ceramic on the reflecting
surface 33a.
[0045]
(Modification 4) As shown in FIG. 6, of the inner wall surface of the waveguide 33, the absorbing
member 36 formed of a material having a higher absorptivity of ultrasonic waves than the
reflecting surface 33a is formed on the surface excluding the reflecting surface 33a. You may
form. The absorbing member 36 can be formed of, for example, a sponge, a rubber, or a resin.
When this configuration is used, ultrasonic waves that are reflected by the inner wall surface of
the waveguide 33 and become noise can be reduced, so that the sensitivity of the receiving
element 10 can be further improved. Furthermore, known geometric sound absorption structures
used in anechoic rooms and the like can also be used. Here, if the absorption member 36 having
an absorptivity of 70% or more is used, noise can be effectively reduced, which is preferable.
Moreover, it can also use together with the reflecting member 35.
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[0046]
(Modification 5) The second opening 33 c is disposed at a position where it can not be visually
recognized from the first opening 33 b, and the reflecting surface 33 a receives the ultrasonic
wave U incident from the first opening 33 b into each receiving element 10. The arrangement of
the first opening 33b, the second opening 33c, and the reflecting surface 33a can be freely set as
long as the light can be reflected in the direction to which it is directed. For example, as shown in
FIG. 7A, the reflecting surface 33a is disposed such that the incident angle θ of the ultrasonic
wave U with respect to the reflecting surface 33a is larger than 45 °, and the direction in which
the ultrasonic wave U is reflected on the reflecting surface 33a The second opening 33c may be
formed along the Further, as shown in FIG. 7B, the waveguides 33 in the arrangement
relationship shown in FIG. 7A can be attached to be inclined with respect to the outer surface of
the body 52. By using this configuration, the direction in which the obstacle M is detected by the
ultrasonic sensor 1 can be changed.
[0047]
(Modification 6) In addition to the receiving element 10, the structure which arrange | positions
the transmitting element which can transmit an ultrasonic wave in the waveguide 33 can also be
used. The ultrasonic wave transmitted from the transmitting element is, for example, reflected in
the direction of the detection object by the reflecting surface 33a. By using this configuration, the
ultrasonic sensor 1 capable of transmission and reception can be mounted on a vehicle without
impairing the design.
[0048]
[Effects of the Best Mode] According to the ultrasonic sensor 1 of the present embodiment, the
ultrasonic waves U reflected by the obstacle M and entering the inside of the waveguide 33 from
the first opening 33 b are reflected by the reflection surface 33 a. Since the ultrasonic waves U
are directly transmitted to the respective receiving elements 10 without passing air to the
medium because they are reflected in the direction toward the plurality of receiving elements 10,
the attenuation of the ultrasonic waves can be reduced. it can. In addition, since the attenuation
of the ultrasonic wave U due to multiple reflection or the like in the waveguide 33 can be
reduced compared to the case where the reflecting surface 33 a is not formed, the sensitivity of
the ultrasonic sensor 1 can be improved. . Furthermore, if the ultrasonic waves U reflected by the
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reflection surface 33 a are arranged to be directly transmitted to the vibrating portion 16, the
displacement of the vibrating portion 16 can be increased, so that the detection signal by the
receiving element 10 becomes large. The sensitivity of the ultrasonic sensor 1 can be improved.
In addition, since the second opening 33 c is disposed at a position not visible from the first
opening 33 b, for example, foreign matter such as pebbles or water droplets fly toward the
waveguide 33 and the first opening Even when the portion 33 b enters the inside of the
waveguide 33, there is no possibility of direct collision with the receiving element 10, so the
receiving element 10 can be protected. That is, the ultrasonic sensor 1 capable of receiving the
ultrasonic waves U efficiently and protecting the receiving element 10 can be realized.
Furthermore, by obtaining the time difference and the phase difference of the ultrasonic waves U
received by the plurality of receiving elements 10, not only the distance to the object to be
detected but also the position of the object to be detected can be measured based on the
respective differences. it can. In addition, it is not necessary to prepare waveguides for a plurality
of receiving elements, and it can be integrated into one waveguide, so the size of the waveguide
can be reduced, and the ultrasonic sensor 1 can be miniaturized. Can be
[0049]
<Other Embodiments> (1) FIG. 8 is a longitudinal cross-sectional explanatory view of an
ultrasonic sensor provided with a transmission member covering the first opening. As shown in
FIG. 8, the transmission member 34 may be formed by covering the first opening 33 b with a
material capable of transmitting an ultrasonic wave to the waveguide 33, for example, a resin
film having a thickness of about 1 mm. With this configuration, since the first opening 33b is
covered by the transmission member 34, there is no possibility that liquid such as small foreign
matter or water droplets may intrude into the waveguide 33, so the receiving element 10 is
protected more reliably. can do. The transmission member 34 may be a material that does not
significantly attenuate ultrasonic waves, and may be a material other than a resin film as long as
it is a size, and for example, metal foil can be used.
[0050]
(2) The ultrasonic sensor 1 can be disposed not only at the body 52 immediately below the
bumper but also at various positions of the vehicle. For example, the first opening 33b can be
attached to a joint, a keyhole, an emblem or the like of the body. By using this configuration, it is
possible to make it difficult to visually recognize the first opening 33b from the outside of the
vehicle, so it is possible to manufacture a vehicle excellent in design. It can also be attached to
other members according to the application of the ultrasonic sensor 1. For example, in the case
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where the ultrasonic sensor 1 is used as an obstacle sensor on the side of the vehicle, the first
opening 33b can be attached to a blinker cover or the like. The ultrasonic sensor 1 can also be
mounted on an antenna. Using this configuration, it is possible to receive ultrasonic waves in all
directions outside the vehicle. In addition, the ultrasonic sensor 1 can be attached to the head
lamp cover, the rear lamp cover, the back lamp cover, and the like.
[0051]
(3) The ultrasonic sensor 1 can be used even in a severe environment where rain, mud splash,
and the like occur. Therefore, the ultrasonic sensor 1 can be suitably used by being used
outdoors such as a vehicle. Besides the vehicle, for example, it can be attached to a robot used
outdoors.
[0052]
It is explanatory drawing of the receiving element of an ultrasonic sensor. FIG. 1A is a plan view
of the receiving element, and FIG. 1B is a cross-sectional view of FIG. 1A taken along the line A-A.
It is explanatory drawing of the ultrasonic sensor of 1st Embodiment. 2 (A) is a longitudinal
sectional view of the ultrasonic sensor, FIG. 2 (B) is a plan view of FIG. 2 (A) seen from the
direction A, and FIG. 2 (C) is a view It is the plane explanatory view which looked at 2 (A) from
the B direction. It is longitudinal cross-section explanatory drawing which shows the example of a
change of a reflective surface. It is longitudinal cross-sectional explanatory drawing which shows
the example of a change of a 1st opening part. It is a longitudinal cross-section explanatory
drawing of the ultrasonic sensor provided with the reflection member which reflects an
ultrasonic wave to a reflective surface. It is a longitudinal cross-sectional explanatory drawing
which equipped the surface other than a reflective surface among the inner wall surfaces of a
waveguide with the absorption member. It is a longitudinal cross-section explanatory drawing
which shows the example of a change of arrangement | positioning of a 1st opening part, a 2nd
opening part, and a reflective surface. It is longitudinal cross-section explanatory drawing of the
ultrasonic sensor which provided the transmission member which covers a 1st opening part.
Explanation of sign
[0053]
DESCRIPTION OF SYMBOLS 1 ultrasonic sensor 10 receiving element 16 vibration part 33
13-04-2019
17
waveguide 33a reflective surface 33b 1st opening part 33c 2nd opening part 34 transmission
member 35 reflection member 36 absorption member M obstacle (a to-be-detected body)
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