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JP2006200976

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DESCRIPTION JP2006200976
The present invention provides a low-cost, compact, lightweight ultrasonic sensor capable of
highly accurately measuring the position and distance of an object to be detected by reducing
acoustic crosstalk between diaphragms. SOLUTION: Each receiving element 11a to 11e
constituting a receiving unit 10 of an ultrasonic sensor has an ultrasonic wave receiving surface
S directed in the same direction, and one end in the length direction is aligned on a straight line
and in the width direction By arranging them almost without any gap, they are one-dimensionally
arranged on the same plane, and the width B and the thickness H are identical, and only the
lengths L are formed to be different. Further, both end portions in the length direction of each of
the receiving elements 11a to 11e are fixed so as not to vibrate. Then, the length L is set such
that the primary resonance frequencies of the respective receiving elements 11a to 11e have
different values. [Selected figure] Figure 1
Ultrasonic sensor
[0001]
The present invention relates to an ultrasonic sensor, and more particularly, to an ultrasonic
sensor that converts received ultrasonic waves into electrical signals or converts electric signals
into ultrasonic waves and transmits them.
[0002]
Conventionally, vertical sonars such as echo sounders and fish finders, horizontal sonars for
measuring the direction of a target object and the distance from the ship, ultrasonic diagnostic
equipment for imaging and diagnosing organs, etc. Ultrasonic sensors are widely used in various
fields.
04-05-2019
1
[0003]
Also, in recent years, an ultrasonic sensor is mounted on a car (vehicle), and the reflection of
ultrasonic waves harmless to the human body transmitted from the ultrasonic sensor is received
to obtain two-dimensional or three-dimensional objects around the car. Technologies are being
developed to perform position measurement and distance measurement, monitor the
surroundings of a car and use it for safe driving.
For example, an ultrasonic sensor is mounted at the rear of a car and a device (generally called
“back sonar”) that detects an object (such as a human or an obstacle) present at the rear of the
car is used to avoid collision with the object Automatic parking support systems have been put to
practical use to support parking at the back.
[0004]
As an ultrasonic sensor (ultrasound probe) used for such position measurement and distance
measurement of an object to be detected, for example, a composite piezoelectric body comprising
a plurality of piezoelectric elements connected via an organic polymer And a plurality of array
electrodes arranged with a gap on one surface of the composite piezoelectric body, wherein a
portion of the composite piezoelectric body corresponding to the gap portion of the array
electrode has an acoustic attenuation coefficient than the organic polymer. The thing filled with
the big filler of is disclosed (refer patent document 1).
JP-A-5-347797 (Pages 2-4, FIGS. 1 to 3)
[0005]
In a conventional ultrasonic sensor including the technique of Patent Document 1, a receiving
unit for converting received (sound receiving) ultrasonic waves into an electric signal includes a
plurality of diaphragms having the same size and shape (array electrode of Patent Document 1)
One-dimensional arrangement in which the two diaphragms are arranged in order in one
direction on the same plane, or in a two-dimensional arrangement in which a plurality of
04-05-2019
2
diaphragms of the same dimensions are arranged in order in the vertical and horizontal
directions on the same plane. Take Then, the transmission unit of the ultrasonic sensor that
converts an electric signal input from the outside into ultrasonic waves and emits (sounds)
transmits ultrasonic waves to the detection target, and the ultrasonic waves are reflected on the
detection target The reflected sound is received by each diaphragm of the receiving unit.
[0006]
Therefore, the receiving unit detects the timing deviation of the ultrasonic waves received by the
plurality of diaphragms (sound receiving plates), and compares the timing deviation of the
received ultrasonic waves with the ultrasonic waves emitted by the transmitting unit. Thus, twodimensional or three-dimensional position measurement of the detection object, distance
measurement between the ultrasonic sensor and the detection object, and the like can be
performed.
[0007]
In addition, the transmitting unit of the conventional ultrasonic sensor usually transmits
ultrasonic waves to a detection target from one diaphragm (sound generation plate).
In addition, although the type which transmits an ultrasonic wave from several diaphragms is
also proposed, the transmission part of the type is a one-dimensional on the same plane several
diaphragms of the same dimension shape similarly to a receiving part. Arranged or arranged in
two dimensions. The reason why the transmitting unit includes a plurality of diaphragms is to
increase the transmission output of ultrasonic waves.
[0008]
By the way, in the conventional receiving unit, since a plurality of diaphragms having the same
size and shape are arranged side by side, all the diaphragms have the same resonance frequency,
and the acoustic crosstalk between the diaphragms is large. As a result, there has been a problem
that the measurement accuracy of the position and distance of the detection object is reduced.
[0009]
Therefore, in the technique of Patent Document 1, the portion of the composite piezoelectric
body located in the gap between a plurality of arrayed electrodes (diaphragm) has a larger sound
attenuation coefficient than the organic polymer constituting the composite piezoelectric body.
04-05-2019
3
By filling the filling material, acoustic crosstalk between each array electrode is reduced to
enhance the azimuth resolution.
[0010]
However, in the technique of Patent Document 1, since a manufacturing process for filling the
filler is required, there is a problem that the manufacturing cost is increased by the
manufacturing process.
Furthermore, in the technique of Patent Document 1, there is also a problem that the overall size
(body size) and weight of the ultrasonic sensor (ultrasound probe) are increased by the volume
and weight of the filler.
Also, in recent years, in order to improve the measurement accuracy of the position and distance
of the detection target, it is required to make the ultrasonic waves transmitted from the
transmitting unit be a chord.
[0011]
The present invention has been made to solve the above problems or to satisfy the above needs,
and has the following objects. (1) To provide a low-cost, compact, lightweight ultrasonic sensor
capable of highly accurately measuring the position and distance of an object to be detected by
reducing acoustic crosstalk between diaphragms. (2) To provide an ultrasonic sensor capable of
converting transmitted ultrasonic waves into chords at low cost.
[0012]
The invention according to claim 1 comprises a plurality of converting means for converting the
received ultrasonic waves into electric signals or converting the electric signals into ultrasonic
waves and transmitting them, and the primary resonance frequencies of the respective
converting means are identical. In order not to do so, the technical feature is an ultrasonic sensor
in which the dimensions of the respective conversion means are irregular.
[0013]
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4
The invention according to claim 2 is the ultrasonic sensor according to claim 1, wherein each of
the conversion means has a flat rectangular shape, and each of the conversion means has a
receiving surface or an ultrasonic wave for receiving ultrasonic waves. The transmitting surfaces
for emitting light are directed in the same direction, and one end in the length direction is
aligned on a straight line and aligned in the width direction, so that they are one-dimensionally
arranged on the same plane, and their width and thickness are the same. The technical feature is
that only the lengths are formed to be different.
[0014]
The invention according to claim 3 is the ultrasonic sensor according to claim 1, wherein each of
the conversion means has a flat rectangular shape, and each of the conversion means has a
receiving surface or an ultrasonic wave for receiving ultrasonic waves. The transmitting surfaces
for transmitting are directed in the same direction, and both ends in the length direction are
aligned on the same straight line and arranged in the width direction, so that they are onedimensionally arranged on the same plane, and their length and thickness are The technical
feature is that they are formed identically, and differ only in width.
[0015]
The invention according to claim 4 is the ultrasonic sensor according to claim 1, wherein each of
the conversion means has a flat rectangular shape, and each of the conversion means has a
receiving surface or an ultrasonic wave for receiving ultrasonic waves. The transmission surfaces
for transmission are oriented in the same direction, and both ends in the length direction are
aligned on the same straight line and aligned in the width direction, so that they are onedimensionally arranged on the same plane, and their length and width are It is a technical feature
that they are formed identically and differ only in thickness.
[0016]
The invention according to claim 5 is the ultrasonic sensor according to claim 1, wherein each of
the conversion means has a flat rectangular shape, and each of the conversion means has a
receiving surface or an ultrasonic wave for receiving ultrasonic waves. By arranging the
transmitting faces for transmitting in the same direction, two-dimensional arrangement is made
in the vertical and horizontal directions on the same plane, and the length, width and thickness
are formed to different dimensions. It features.
[0017]
The invention according to claim 6 is the ultrasonic sensor according to any one of claims 2 to 5,
wherein each of the conversion means is arranged such that the reception surface or the
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5
transmission surface is flush. Technical features.
[0018]
The invention according to claim 7 is the ultrasonic sensor according to any one of claims 2 to 6,
wherein each of the conversion means is fixed so as not to vibrate at both ends in the
longitudinal direction. It is a technical feature.
[0019]
The invention according to claim 8 is the ultrasonic sensor according to claim 7, wherein the
resonance value Q of each of the conversion means is the same, and the primary resonance
frequency f1 of any one of the conversion means is the same. And the primary resonance
frequency f of the conversion means having the larger or smaller size next to the conversion
means is expressed by the following equation using an arbitrary coefficient n which is an integer:
Do.
f=f1±n×f1/Q
[0020]
The invention according to claim 9 is technically characterized in that in the ultrasonic sensor
according to claim 8, the coefficient n = 7 or the coefficient n = 8.
[0021]
The ultrasonic sensor according to claim 10, wherein the length L, the width B, the thickness H,
and the primary resonance frequency f of each of the conversion means are expressed by the
following formulas. It is a technical feature to be represented.
f=(B×H<3>)<1/2>/L<2>
[0022]
The invention according to claim 11 is a technical feature in the ultrasonic sensor according to
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any one of claims 1 to 10, wherein the conversion means is a piezoelectric type or a capacitance
type.
[0023]
(Claim 1) In the invention of claim 1, when each converting means is made to function as a
receiving element for converting received ultrasonic waves into electric signals and each
converting means constitutes a receiving unit, the receiving unit is separate from the receiving
unit. The transmitting unit of the provided ultrasonic sensor transmits an ultrasonic wave to the
detection target, and the reflected sound reflected by the ultrasonic wave on the detection target
is received by each receiving element (conversion means) of the receiving unit.
Then, the receiving unit detects the timing shift of the ultrasonic waves received by each
receiving element (conversion means), and the detection timing is detected by comparing the
timing shift of the received ultrasonic waves with the ultrasonic waves emitted by the
transmitting unit. The two-dimensional or three-dimensional position measurement of the object,
the distance measurement between the ultrasonic sensor and the detection object, and the like
can be performed.
[0024]
Therefore, if the dimensions of the respective receiving elements are made uneven so that the
primary resonance frequencies of the respective receiving elements (conversion means) do not
match, the influence of the respective receiving elements on each other's vibration can be made a
small value that can almost be ignored. It is possible to reduce the acoustic crosstalk between the
receiving elements and to improve the measurement accuracy of the position and distance of the
detection object.
[0025]
Therefore, according to the invention of claim 1, it is only necessary to make the dimensions of
the respective receiving elements (conversion means) different, and no special process is
required for the production of the ultrasonic sensor. The manufacturing cost of the ultrasonic
sensor can be reduced as compared to the technique of Patent Document 1 that requires a
process.
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Further, according to the invention of claim 1, only the dimensions of the respective receiving
elements (conversion means) may be made different, and if only a very slight gap to the extent
that the vibration is not directly transmitted is provided between the respective receiving
elements. Since it is good, the ultrasonic sensor can be made smaller and lighter than the
technology of Patent Document 1 in which the overall size and weight increase by the volume
and weight of the filler.
The number of receiving elements (conversion means) and the arrangement interval may be set
by experimentally finding an optimum value by cut-and-try according to the required
measurement accuracy.
[0026]
In the invention of claim 1, when each converting means is made to function as a transmitting
element for converting an electric signal input from the outside into an ultrasonic wave and
transmitting it, and each transmitting means is constituted of a transmitting unit, each
transmitting element Since the primary resonance frequencies of are set to different values, it is
possible to make the ultrasonic waves transmitted from the respective transmitting elements
(conversion means) into a chord.
[0027]
(Claim 2: corresponds to the first embodiment) According to the invention of claim 2, only a very
small gap to the extent that vibration is not directly transmitted is provided between each
conversion means, and each conversion means is arranged, each conversion means It is possible
to obtain the action and effect of the invention of claim 1 only by changing only the length of.
[0028]
According to the third aspect of the present invention, the conversion means are arranged by
providing only a very small gap to the extent that the vibration is not directly transmitted
between the conversion means. It is possible to obtain the action and effect of the invention of
claim 1 only by making only the width of the difference.
Further, according to the invention of claim 3, since the whole shape of the receiving part or the
transmission part is a flat rectangular shape, the structures of both ends in the length direction of
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8
each conversion means are simplified as compared with the invention of claim 2. The
manufacturing cost of the ultrasonic sensor can be further reduced because it becomes possible
to make the ultrasonic sensor easy to manufacture.
[0029]
(Fourth aspect: fall under the third embodiment) According to the fourth aspect of the invention,
only a very small gap to the extent that vibration is not directly transmitted is provided between
the conversion means, and the conversion means are arranged, and the conversion means are
provided. It is possible to obtain the operation and effect of the invention of claim 1 by changing
only the thickness of.
Further, according to the invention of claim 4, the width of the receiving unit or the transmitting
unit is smaller than that of the invention according to the invention of claim 3, and the planar
dimension when the receiving unit or the transmitting unit is viewed from above is reduced.
Alternatively, it is possible to reduce the volume when the transmitting unit is housed in a
package, and the ultrasonic sensor can be further miniaturized and reduced in weight.
[0030]
(Claim 5: Corresponding to the fourth embodiment) According to the invention of claim 5, only a
very small gap to the extent that vibration is not directly transmitted is provided between each
conversion means, and each conversion means is arranged, each conversion portion By setting
the length, width, and thickness to different dimensions, it is possible to obtain the operation and
effect of the invention of claim 1.
Further, according to the invention of claim 5, when each converting means is made to function
as a receiving element by arranging each converting means in two dimensions, the measurement
accuracy of the position and distance of the detection object is further enhanced. it can.
[0031]
(Claim 6) According to the invention of claim 6, by disposing the receiving surface or the
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9
transmitting surface of each conversion means flush, it is possible to improve the measurement
accuracy of the position and distance of the detection object.
In addition, when each conversion means is made to function as a receiving element, if the
receiving surfaces of the receiving elements are not arranged flush, the timing deviation of the
ultrasonic waves received by each receiving element must be corrected. Complex signal
processing circuits are required to process the electrical signals generated by the receiver.
On the other hand, according to the invention of claim 6, there is no need to correct the timing
deviation of the ultrasonic waves received by each receiving element (conversion means), and a
signal processing circuit for processing the electric signal generated by the receiving unit is
provided. It can be simplified.
[0032]
(Claim 7) According to the invention of claim 7, the actions and effects of claim 1 can be obtained
with certainty.
[0033]
(Claim 8) According to the invention of claim 8, when each conversion means is made to function
as a reception element as the coefficient n in the equation is set to a larger value, the primary
order of each reception element (conversion means) Since the difference between the resonance
frequencies becomes large, the influence of the respective receiving elements on each other's
vibration becomes small, and the measurement accuracy of the position and distance of the
object to be detected can be increased.
However, as the coefficient n is set to a larger value, the dimensional difference between the
receiving elements becomes larger, and the overall size and weight of the receiving unit also
become larger.
Therefore, the value of the coefficient n may be set by experimentally finding an optimum value
by cut and try according to the required measurement accuracy.
04-05-2019
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[0034]
(Aspect 9) If the coefficient n = 7 or the coefficient n = 8 is set as in the invention of the ninth
aspect, the operation and effect of the first aspect can be sufficiently obtained in practice.
[0035]
(Claim 10) According to the invention of claim 10, the actions and effects of claim 1 can be
obtained with certainty.
[0036]
According to the invention of claim 11, it is possible to obtain a piezoelectric or capacitive
ultrasonic sensor.
[0037]
Hereinafter, embodiments of the present invention will be described with reference to the
drawings.
In each embodiment, the same reference numerals are given to the same components as in the
first embodiment, and the redundant description is omitted for the same content.
[0038]
First Embodiment FIG. 1 is a perspective view of a receiving unit 10 of an ultrasonic sensor
according to a first embodiment.
The receiving unit 10 includes five receiving elements (conversion means) 11 a to 11 e.
In the flat rectangular receiving elements 11a to 11e, the receiving surface S of the ultrasonic
waves is directed in the same direction, and one end in the length direction is aligned on a
straight line and the receiving surface S is aligned with almost no gap in the width direction.
They are one-dimensionally arranged on the same plane so that S is flush, and the width B and
the thickness H are the same, and only the lengths L are formed to be different.
04-05-2019
11
[0039]
And both ends in the length direction of each of the receiving elements 11a to 11e are fixed in a
non-vibratable manner by being attached to a fixing member (not shown).
The receiving unit 10 may be manufactured by any method, for example, the receiving elements
11a to 11e manufactured separately may be assembled, and a semiconductor substrate using
MEMS (Micro Electro Mechanical Systems) technology. It may be integrally formed on top.
[0040]
[Structure of Reception Element] FIGS. 2 to 4 are schematic vertical cross-sectional views
showing first to third structural examples of the reception elements 11a to 11e. In FIGS. 2 to 4,
the thickness direction (height direction) is exaggerated.
[0041]
<First Structural Example> In the first structural example shown in FIG. 2, each of the
piezoelectric receiving elements 11 a to 11 e includes the lower electrode 21, the receiving
electrodes 22 a to 22 e, and the composite piezoelectric body 23. In FIG. 2, only the receiving
elements 11a, 11b and 11d and the receiving electrodes 22a, 22b and 22d are illustrated.
[0042]
The flat rectangular receiving electrodes 22a to 22e are provided independently for each of the
receiving elements 11a to 11e. Between the reception electrodes 22a to 22e, a very small gap to
the extent that the vibration of the adjacent reception electrodes 22a to 22e is not directly
transmitted is provided, and they are arranged almost without any gap.
[0043]
04-05-2019
12
The receiving electrodes 22 a to 22 e and the flat lower electrode 21 are disposed in parallel, and
the composite piezoelectric body 23 is interposed between the receiving electrodes 22 a to 22 e
and the lower electrode 21. The composite piezoelectric body 23 is composed of a plurality of
columnar piezoelectric elements 24 and an organic polymer layer 25. Each piezoelectric element
24 is connected to only one reception electrode 22a to 22e, and is arranged so as not to be
connected to two adjacent reception electrodes 22a to 22e.
[0044]
The upper and lower ends of each piezoelectric element 24 are respectively connected to the
receiving electrodes 22 a to 22 e and the lower electrode 21. The organic polymer layer 25 is
filled in the gaps of the piezoelectric elements 24 to bond the piezoelectric elements 24 to each
other. That is, each piezoelectric element 24 is embedded in the organic polymer layer 25. Each
piezoelectric element 24 is made of a ferroelectric (for example, PZT or the like). The organic
polymer layer 25 is made of, for example, silicone rubber, epoxy resin, polyurethane resin or the
like.
[0045]
Then, the reception element 11a is formed of the reception electrode 22a, the composite
piezoelectric body 23, and the lower electrode 21 stacked, and the reception element 11b is
formed of the reception electrode 22b, the composite piezoelectric body 23, and the lower
electrode 21 stacked. Each receiving element 11a-11e of the structure which interposes the
composite piezoelectric material 23 by each receiving electrode 22a-22e and the lower electrode
21 is formed.
[0046]
Here, when the surface of the receiving electrodes 22a to 22e becomes the receiving surface S of
ultrasonic waves and the receiving electrodes 22a to 22e vibrate by ultrasonic waves, the
vibrations are transmitted to the composite piezoelectric body 23, and when the composite
piezoelectric body 23 vibrates, piezoelectric An electric signal is generated by the effect, and the
electric signal is output through a wire (not shown) connected to the receiving electrodes 22 a to
22 e and the lower electrode 22.
04-05-2019
13
That is, in each of the receiving elements 11a to 11e of the first structural example, a diaphragm
(a sound receiving plate) is formed by the laminated structure of the receiving electrodes 22a to
22e, the lower electrode 21 and the composite piezoelectric body 23, and the diaphragm receives
The ultrasound is converted to an electrical signal.
[0047]
Second Structural Example In the second structural example shown in FIG. 3, each of the
piezoelectric receiving elements 11a to 11e includes the lower electrode 21, the receiving
electrodes 22a to 22e, the dielectric layers 31a to 31e, and the like. In FIG. 3, only the receiving
elements 11a, 11b and 11d, the receiving electrodes 22a, 22b and 22d, and the dielectric layers
31a, 31b and 31d are illustrated. Between each of the receiving electrodes 22a to 22e and the
lower electrode 21, dielectric layers 31a to 31e made of a ferroelectric (for example, PZT or the
like) are interposed.
[0048]
Then, the reception element 11a is formed of the laminated reception electrode 22a, the
dielectric layer 31a, and the lower electrode 21, and the reception element 11b is formed of the
laminated reception electrode 22b, the dielectric layer 31b, and the lower electrode 21. The
respective receiving elements 11a to 11e are formed accordingly. Between the reception
electrodes 22a to 22e and the dielectric layers 31a to 31e, very small gaps are provided to the
extent that the vibrations of the adjacent reception electrodes 22a to 22e and the dielectric
layers 31a to 31e are not directly transmitted. Only, they are lined up almost without gaps.
[0049]
Here, when the surfaces of the receiving electrodes 22a to 22e become the receiving surface S of
ultrasonic waves and the receiving electrodes 22a to 22e vibrate by ultrasonic waves, the
vibrations are transmitted to the dielectric layers 31a to 31e, and the dielectric layers 31a to 31e
When is vibrated, an electric signal is generated by the piezoelectric effect, and the electric signal
is output through a wire (not shown) connected to the receiving electrodes 22 a to 22 e and the
lower electrode 22. That is, in each of the receiving elements 11a to 11e of the second structural
example, a diaphragm (a sound receiving plate) is formed of the laminated structure of the
04-05-2019
14
receiving electrodes 22a to 22e, the lower electrode 21 and the dielectric layers 31a to 31e. The
received ultrasonic waves are converted into electrical signals.
[0050]
<Third Structural Example> In the third structural example shown in FIG. 4, each of the
capacitive type (capacitor type) receiving elements 11 a to 11 e includes the lower electrode 21,
the receiving electrodes 22 a to 22 e, and the holding member 41. ing. Holding members 41 are
interposed between both ends of the receiving electrodes 22a to 22e and the lower electrode 21.
The receiving electrodes 22a to 22e and the lower electrode 21 are opposed to each other with a
gap K. The lower electrode 21 is fixed so as not to vibrate to constitute a fixed electrode, and
each of the receiving electrodes 22a to 22e is capable of vibrating to constitute a movable
electrode.
[0051]
The receiving elements 11a to 11e are formed such that the receiving element 11a is composed
of the receiving electrode 22a and the lower electrode 21 and the receiving element 11b is
composed of the receiving electrode 22b and the lower electrode 21. Between the reception
electrodes 22a to 22e, a very small gap to the extent that the vibration of the adjacent reception
electrodes 22a to 22e is not directly transmitted is provided, and they are arranged almost
without any gap.
[0052]
Here, when the surface of the receiving electrodes 22a to 22e becomes the receiving surface S of
ultrasonic waves and the receiving electrodes 22a to 22e are vibrated by the ultrasonic waves,
the distance between the receiving electrodes 22a to 22e and the lower electrode 21 changes,
and the receiving electrode 22a The capacitance between the lower electrode 21 and the lower
electrode 21 also changes. Therefore, using the conversion circuit (not shown) connected to each
of the receiving electrodes 22a to 22e and the lower electrode 21 through the wiring (not
shown), the capacitance between each of the receiving electrodes 22a to 22e and the lower
electrode 21 is obtained. Convert the change in the signal into an electrical signal. That is, in each
of the receiving elements 11a to 11e of the third structural example, a diaphragm (sound
receiving plate) is configured from the receiving electrodes 22a to 22e, and the ultrasonic waves
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received by the diaphragm are converted into electric signals.
[0053]
[Operation and Effect of First Embodiment] According to the first embodiment, the following
operation and effect can be obtained.
[0054]
[1-1] A transmitting unit (not shown) of an ultrasonic sensor provided separately from the
receiving unit 10 transmits an ultrasonic wave to the detection object, and a reflected sound in
which the ultrasonic wave is reflected on the detection object Are received by the receiving
elements 11 a to 11 e of the receiving unit 10.
[0055]
Then, the reception unit 10 detects the deviation of the timing of the ultrasonic waves received
by each of the receiving elements 11a to 11e, and compares the deviation of the timing of the
received ultrasonic waves with the ultrasonic waves emitted by the transmitter. The twodimensional or three-dimensional position measurement of the object, the distance measurement
between the ultrasonic sensor and the detection object, and the like can be performed.
Note that any type (for example, a piezoelectric type, a capacitance type, etc.) may be used for the
transmission unit of the ultrasonic sensor.
[0056]
[1-2] FIG. 5 is a characteristic diagram showing a resonance characteristic which is a relationship
between the frequency f of the diaphragm fixed at both ends and the displacement x of the
vibration.
The displacement x at an arbitrary frequency f is obtained by Equation 1 from the maximum
value Xmax of the displacement, the primary resonance frequency f1, and the resonance value Q.
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[0057]
[0058]
As shown in FIG. 5, the displacement x at a frequency f (= f1 ± 8 × f1 / Q) shifted from the
primary resonance frequency f1 by ± 8 × f1 / Q is 1/256 of the maximum value Xmax of the
displacement. Is given by Equation 1.
[0059]
Here, since each of the receiving elements 11a to 11e constituting the receiving unit 10 can be
regarded as a diaphragm fixed at both ends, the relationships shown in FIG. 5 and Formula 1
hold also for each of the receiving elements 11a to 11e.
If the structures of the receiving elements 11a to 11e are the same, their resonance values Q
become the same.
[0060]
Therefore, for the reception element 11a of the primary resonance frequency F1a, the primary
resonance frequencies of the reception elements 11b and 11d arranged side by side on both
sides thereof are set to frequencies F1b and F1d (= F1a ± 8 × F1a / Q) If this is done, it is
possible to reduce the influence of the respective receiving elements 11a, 11b, 11d to each other
by 1/256.
That is, the primary resonance frequency of the receiving element 11b may be set to F1b (= F1a
+ 8 × F1a / Q). Further, the primary resonance frequency of the receiving element 11d may be
set to F1d (= F1a-8 × F1a / Q).
[0061]
Similarly, with respect to the primary resonance frequency F1b (= F1a + 8 × F1a / Q) of the
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reception element 11b, the primary resonance frequency of the reception element 11c arranged
in parallel to the reception element 11b is F1c (= F1b + 8 × F1b / Q) It should be set to Further,
for the primary resonance frequency F1d (= F1a-8 × F1a / Q) of the reception element 11d, the
primary resonance frequency of the reception element 11e arranged in parallel to the reception
element 11d is F1e (= F1d-8 × F1d It should be set to / Q).
[0062]
As described above, if the primary resonance frequencies F1a to F1e of the respective receiving
elements 11a to 11e are set to different values, the influence of the respective receiving elements
11a to 11e on each other's vibration can be reduced to a small value of almost 1/256. It is
possible to reduce the acoustic crosstalk between the receiving elements 11a to 11e and to
improve the measurement accuracy of the position and distance of the detection object.
[0063]
[1-3] The primary resonance frequency f1 of the diaphragm fixed at both ends is expressed by
Formula 2 from the length L of the diaphragm, the width B of the diaphragm, and the thickness H
(thickness in the bending direction) of the diaphragm. Desired.
[0064]
[0065]
Here, since each of the receiving elements 11a to 11e constituting the receiving unit 10 can be
regarded as a diaphragm fixed at both ends, the relationship shown in Formula 2 also holds for
each of the receiving elements 11a to 11e.
The respective receiving elements 11a to 11e are formed so that the width B and the thickness H
are the same and only the length L is different. Therefore, the width B and the thickness H are
constant, and the lengths of the respective receiving elements 11a to 11e are La to Le.
[0066]
Then, the primary resonance frequencies F1a to F1e of the receiving elements 11a to 11e are
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represented by Formula 2 to Formula 3 to Formula 7, respectively.
Note that α = (B × H <3>) <1/2>.
[0067]
[0068]
[0069]
[0070]
[0071]
[0072]
Then, equation (8) can be obtained by substituting equation (3) and equation (4) into the primary
resonance frequency F1b (= F1a + 8 × F1a / Q) of the reception element 11b.
Further, equation (9) can be obtained by substituting equation (3) and equation (6) into the
primary resonance frequency F1d (= F1a-8 × F1a / Q) of the reception element 11d.
Formula 10 is obtained by substituting Formula 4 and Formula 5 for the primary resonance
frequency F1c (= F1b + 8 × F1b / Q) of the reception element 11c and substituting Formula 8
for the obtained formula.
Formula 11 is obtained by substituting Formula 6 and Formula 7 into the primary resonance
frequency F1e (= F1d−8 × F1d / Q) of the reception element 11e and substituting Formula 9
into the obtained formula.
04-05-2019
19
[0073]
[0074]
[0075]
[0076]
[0077]
Therefore, if resonance values Q determined by the structure of each of the receiving elements
11a to 11e are obtained by measurement or simulation, and the resonance values Q are
substituted into Expressions 8 to 11, each reception for the length La of the receiving elements
11a The lengths Lb to Le of the elements 11b to 11e can be obtained.
For example, in the case of the resonance value Q = 60, the length Lb of the receiving element
11b = about 0.94 × La, the length Lb of the receiving element 11c = about 0.88 with respect to
the length La of the receiving element 11a. X La, length Ld of receiving element 11 d = about
1.07 x La, length Le of receiving element 11 e = about 1.15 x La.
[0078]
[1-4] If the lengths La to Le of the receiving elements 11a to 11e are set to different values as in
[1-3], the operation and effects of [1-2] can be obtained.
That is, in the first embodiment, the lengths La to Le of the receiving elements 11a to 11e are
uneven so that the resonant frequencies of the receiving elements 11a to 11e do not coincide
with one another. Acoustic crosstalk can be reduced, and the measurement accuracy of the
position and distance of the detection object can be increased.
04-05-2019
20
[0079]
Then, according to the first embodiment, only the lengths La to Le of the respective receiving
elements 11a to 11e may be made different, and a special process is not necessary for
manufacturing the receiving unit 10, so that the filling material is filled. The manufacturing cost
of the receiving unit 10 can be reduced as compared with the technique of Patent Document 1
that requires the manufacturing process of.
[0080]
Further, according to the first embodiment, only the lengths La to Le of the respective receiving
elements 11a to 11e may be made different, and a very slight gap to the extent that vibration is
not directly transmitted between the respective receiving elements 11a to 11e. As compared with
the technique of Patent Document 1 in which the overall size and weight increase by the volume
and weight of the filler, the size and weight of the receiving unit 10 can be reduced.
[0081]
[1-5] FIG. 6 is a perspective view showing a first modified example of the first embodiment.
In the example shown in FIG. 1, the receiving elements 11a to 11e are arranged such that one
end in the longitudinal direction is aligned on a straight line.
However, as in the first modified example shown in FIG. 6, the both end portions of the
respective receiving elements 11a to 11e may be appropriately arranged and arranged without
being aligned.
[0082]
FIG. 7 is a perspective view showing a second modification of the first embodiment.
In the example shown in FIG. 1, the receiving elements 11 a to 11 e are arranged in order of the
length L.
04-05-2019
21
However, as in the second modified example shown in FIG. 7, the receiving elements 11 a to 11 e
may be appropriately arranged and arranged regardless of the length L.
[0083]
When vibration transmission between the receiving elements 11a to 11e is completely cut off,
the acoustic crosstalk reduction effect in the example shown in FIG. 1 and the first modification
or the second modification is the same.
However, in practice, the vibration transmission between the receiving elements 11a to 11e can
not be completely cut off, so that the vibration transmission causes the acoustic transmission in
the example shown in FIG. 1 and the first modification or the second modification. There are
some differences in the crosstalk reduction effect.
[0084]
Second Embodiment FIG. 8 is a perspective view of a receiving unit 50 of an ultrasonic sensor
according to a second embodiment.
The receiving unit 50 includes five receiving elements (conversion means) 51a to 51e.
Each of the flat rectangular receiving elements 51a to 51e has the ultrasonic wave receiving
surface S oriented in the same direction, and both ends in the length direction are aligned on a
straight line and arranged almost without gaps in the width direction. They are onedimensionally arranged on the same plane so that the surfaces S are flush with each other, the
length L and the thickness H are the same, and only the width B is formed to be different.
[0085]
And both ends in the length direction of each of the receiving elements 51a to 51e are fixed to a
non-vibratable state by being attached to a fixing member (not shown). The receiving unit 50
may be manufactured by any method. For example, the reception elements 51a to 51e
04-05-2019
22
manufactured separately may be assembled, and integrally formed on a semiconductor substrate
using MEMS technology. It is also good. The structures of the receiving elements 51a to 51e are
the same as the receiving elements 11a to 11e of the first embodiment.
[0086]
[Operation / Effect of Second Embodiment] According to the second embodiment, in addition to
the same operation / effect as the above-mentioned [1-1] of the first embodiment can be
obtained, the following operation / effect can be obtained Can.
[0087]
[2-1] As in the case of [1-2] of the first embodiment, the receiving elements 51a to 51e
constituting the receiving unit 50 can be regarded as diaphragms whose both ends are fixed. The
relationship shown in FIG.
[0088]
Therefore, for the reception element 51a of the primary resonance frequency F5a, the primary
resonance frequencies of the reception elements 51b and 51d arranged side by side on both
sides thereof are set to frequencies F5b and F5d (= F5a ± 8 × F5a / Q), respectively. If this is
done, it is possible to reduce the influence of the respective receiving elements 51a, 51b, 51d to
each other by 1/256.
That is, the primary resonance frequency of the receiving element 51b may be set to F5b (= F5a
+ 8 × F5a / Q).
Further, the primary resonance frequency of the receiving element 51d may be set to F5d (= F5a8 × F5a / Q).
[0089]
Similarly, for the primary resonance frequency F5b (= F5a + 8 × F5a / Q) of the reception
element 51b, the primary resonance frequency of the reception element 51c arranged in parallel
to the reception element 51b is F5c (= F5b + 8 × F5b / Q) It should be set to Further, with
04-05-2019
23
respect to the primary resonance frequency F5d (= F5a-8 × F5a / Q) of the reception element
51d, the primary resonance frequency of the reception element 51e arranged in parallel to the
reception element 51d is F5e (= F5d-8 × F5d) It should be set to / Q).
[0090]
As described above, if the primary resonance frequencies F5a to F5e of the reception elements
51a to 51e are set to different values, the influence of the respective reception elements 51a to
51e on each other can be minimized to a small value of 1/256. It is possible to reduce the
acoustic crosstalk between the receiving elements 51a to 51e, and to improve the measurement
accuracy of the position and distance of the detection target.
[0091]
[2-2] As in the case of [1-3] of the first embodiment, each of the receiving elements 51a to 51e
constituting the receiving unit 50 can be regarded as a diaphragm fixed at both ends. The
relationship shown in Formula 2 is established in 51e.
Each of the receiving elements 51a to 51e has the same length L and thickness H and is formed
to differ only in the width B. Therefore, the length L and the thickness H are constants, and the
widths of the respective receiving elements 51a to 51e are Assume Ba to Be.
[0092]
Then, primary resonance frequencies F5a to F5e of the reception elements 51a to 51e are
represented by Formula 2 to Formula 12 to Formula 16, respectively. Note that β = H <3/2> / L
<2>.
[0093]
[0094]
[0095]
04-05-2019
24
[0096]
[0097]
[0098]
Then, equation (17) is obtained by substituting equation (12) and equation (13) into the primary
resonance frequency F5b (= F5a + 8 × F5a / Q) of the reception element 51b.
Further, equation (18) can be obtained by substituting equation (12) and equation (15) into the
primary resonance frequency F5d (= F5a-8 × F5a / Q) of the reception element 51d.
Further, Formula 13 and Formula 14 are substituted for the primary resonance frequency F5c (=
F5b + 8 × F5b / Q) of the reception element 51c, and Formula 17 is substituted for the obtained
formula to obtain Formula 19.
Formula 20 is obtained by substituting Formula 15 and Formula 16 for the primary resonance
frequency F 5 e (= F 5 d−8 × F 5 d / Q) of the receiving element 51 e and substituting Formula
18 for the obtained formula.
[0099]
[0100]
[0101]
[0102]
04-05-2019
25
[0103]
Therefore, if resonance value Q determined by the structure of each of the receiving elements
51a to 51e is obtained by measurement or simulation, and the resonance value Q is substituted
into Formula 17 to Formula 20, each receiving element with respect to the width Ba of receiving
element 51a The widths Bb to Be of 51b to 51e can be obtained.
For example, in the case of the resonance value Q = 60, the width Bb of the reception element
51b is about 0.75 × Ba, the width Bb of the reception element 51c is about 0.56 × Ba, with
respect to the width Ba of the reception element 51a. The width Bd of the reception element 51 d
is approximately 1.28 × Ba, and the width Be of the reception element 51 e is approximately
1.65 × Ba.
[0104]
[2-3] If the widths Ba to Be of the receiving elements 51a to 51e are set to different values as in
[2-2], the operation and effects of the [2-1] can be obtained.
That is, in the second embodiment, the widths Ba to Be of the receiving elements 51a to 51e are
unequal so that the resonance frequencies of the receiving elements 51a to 51e do not coincide
with each other. Crosstalk can be reduced, and the measurement accuracy of the position and
distance of the detection target can be increased.
[0105]
Then, according to the second embodiment, only the widths Ba to Be of the respective receiving
elements 51a to 51e may be made different, and a special process is not necessary for
manufacturing the receiving unit 50. The manufacturing cost of the receiving unit 50 can be
reduced compared to the technology of Patent Document 1 that requires a manufacturing
process.
[0106]
Further, according to the second embodiment, only the widths Ba to Be of the respective
receiving elements 51a to 51e may be made different, and only a very small gap to the extent
that vibration is not directly transmitted between the respective receiving elements 51a to 51e.
04-05-2019
26
As compared with the technique of Patent Document 1 in which the overall size and weight are
increased by the volume and weight of the filler, the size and weight of the receiving unit 50 can
be reduced.
[0107]
Furthermore, in the second embodiment, since the entire shape of the receiving unit 50 is a flat
rectangular shape, the fixing structure of both end portions in the longitudinal direction of each
of the receiving elements 51a to 51e is simplified as compared to the first embodiment. Since the
manufacturing of the receiving unit 50 becomes easy, the manufacturing cost of the receiving
unit 50 can be further reduced.
[0108]
[2-4] FIG. 9 is a perspective view showing a modification of the second embodiment.
In the example shown in FIG. 8, the receiving elements 51 a to 51 e are arranged in the order of
the width B.
However, as in the modification shown in FIG. 9, the receiving elements 51 a to 51 e may be
appropriately arranged and arranged regardless of the width B.
[0109]
When vibration transmission between the receiving elements 51a to 51e is completely cut off,
the acoustic crosstalk reduction effect in the example shown in FIG. 8 and the modification
shown in FIG. 9 are the same.
However, in practice, the vibration transmission between the receiving elements 51a to 51e can
not be completely cut off, so that the acoustic transmission of the acoustic crosstalk in the
example shown in FIG. 8 and the modification shown in FIG. There are some differences in the
reduction effect.
04-05-2019
27
[0110]
Third Embodiment FIG. 10 is a perspective view of a receiving unit 60 of an ultrasonic sensor
according to a third embodiment.
The receiving unit 60 is composed of five receiving elements (conversion means) 61a to 61e.
In the flat rectangular receiving elements 61a to 61e, the receiving surfaces S of the ultrasonic
waves are directed in the same direction, and both ends in the length direction are aligned on a
straight line and arranged almost without gaps in the width direction. They are onedimensionally arranged on the same plane so that the surfaces S are flush with each other, and
the lengths L and B are the same, and only the thickness H is formed to be different.
[0111]
And both ends in the length direction of each of the receiving elements 61a to 61e are fixed to a
fixed member (not shown) so that they can not vibrate.
The receiving unit 60 may be manufactured by any method. For example, the reception elements
61a to 61e manufactured separately may be assembled, and integrally formed on a
semiconductor substrate using MEMS technology. It is also good.
The structures of the receiving elements 61a to 61e are the same as the receiving elements 11a
to 11e of the first embodiment.
[0112]
[Operation / Effect of Third Embodiment] According to the third embodiment, in addition to the
same operation / effect as the above-mentioned [1-1] of the first embodiment can be obtained,
the following operation / effect can be obtained Can.
[0113]
[3-1] As in the case of [1-2] of the first embodiment, each of the receiving elements 61a to 61e
04-05-2019
28
constituting the receiving unit 60 can be regarded as a diaphragm fixed at both ends. The
relationship shown in FIG.
[0114]
Therefore, for the reception element 61a of the primary resonance frequency F6a, the primary
resonance frequencies of the reception elements 61b and 61d arranged next to each other are
set to frequencies F6b and F6d (= F6a ± 8 × F6a / Q), respectively. If this is done, it is possible
to reduce the influence that each receiving element 61a, 61b, 61d receives from each other's
vibration to 1/256.
That is, the primary resonance frequency of the receiving element 61b may be set to F6b (= F6a
+ 8 × F6a / Q).
Further, the primary resonance frequency of the receiving element 61d may be set to F6d (= F6a8 × F6a / Q).
[0115]
Similarly, for the primary resonance frequency F6b (= F6a + 8 × F6a / Q) of the reception
element 61b, the primary resonance frequency of the reception element 61c arranged in parallel
to the reception element 61b is F6c (= F6b + 8 × F6b / Q) It should be set to Further, with
respect to the primary resonance frequency F6d (= F6a-8 × F6a / Q) of the reception element
61d, the primary resonance frequency of the reception element 61e arranged in parallel to the
reception element 61d is F6e (= F6d-8 × F6d) It should be set to / Q).
[0116]
In this way, if the primary resonance frequencies F6a to F6e of the respective receiving elements
61a to 61e are set to different values, the influence of the respective receiving elements 61a to
61e on each other's vibration can be reduced to a small value of almost 1/256. It is possible to
reduce the acoustic crosstalk between the receiving elements 61a to 61e, and to improve the
measurement accuracy of the position and distance of the detection target.
04-05-2019
29
[0117]
[3-2] As in the case of [1-3] of the first embodiment, each of the receiving elements 61a to 61e
constituting the receiving unit 60 can be regarded as a diaphragm fixed at both ends. The
relationship shown in Formula 2 is established in 61e.
Each of the receiving elements 61a to 61e has the same length L and width B and only the
thickness H. Therefore, the length L and the width B are constant, and the thicknesses of the
receiving elements 61a to 61e are set. Ha to He.
[0118]
Then, primary resonance frequencies F6a to F6e of the respective receiving elements 61a to 61e
are represented by Formula 2 to Formula 21 to Formula 25. Note that γ = B <1/2> / L <2>.
[0119]
[0120]
[0121]
[0122]
[0123]
[0124]
Then, Formula 26 is obtained by substituting Formula 21 and Formula 22 into the primary
resonance frequency F6b (= F6a + 8 × F6a / Q) of the reception element 61b.
04-05-2019
30
Further, equation (27) can be obtained by substituting equation (21) and equation (24) into the
primary resonance frequency F6d (= F6a-8 × F6a / Q) of the reception element 61d.
Formula 28 and Formula 23 are substituted into the primary resonance frequency F 6 c (= F 6 b
+ 8 × F 6 b / Q) of the reception element 61 c, and Formula 26 is substituted into the obtained
formula to obtain Formula 28.
By substituting Formula 24 and Formula 25 into the primary resonance frequency F 6 e (= F 6
d−8 × F 6 d / Q) of the receiving element 61 e and substituting Formula 27 into the obtained
formula, Formula 29 can be obtained.
[0125]
[0126]
[0127]
[0128]
[0129]
Therefore, if the resonance value Q determined by the structure of each of the receiving elements
61a to 61e is obtained by measurement or simulation, and the resonance value Q is substituted
into Equations 26 to 29, each receiving element for the thickness Ha of the receiving element
61a Thicknesses Hb to Be of 61b to 61e can be obtained.
For example, in the case of the resonance value Q = 60, the thickness Hb of the reception
element 61b is about 0.91 × Ha, the thickness Hb of the reception element 61c is about 0.83 ×
Ha, with respect to the thickness Ha of the reception element 61a. The thickness Hd of the
receiving element 61 d is approximately 1.09 × Ha, and the thickness He of the receiving
element 61 e is approximately 1.18 × Ha.
04-05-2019
31
[0130]
[3-3] If the thicknesses Ha to He of the receiving elements 61a to 61e are set to different values
as in [3-2], the operation and effect of the [3-1] can be obtained.
That is, in the third embodiment, by making the thicknesses Ha to He of the receiving elements
61a to 61e uneven so that the resonance frequencies of the receiving elements 61a to 61e do
not match, the sound between the receiving elements 61a to 61e is generated. Crosstalk can be
reduced, and the measurement accuracy of the position and distance of the detection target can
be increased.
[0131]
Then, according to the third embodiment, only the thicknesses Ha to He of the respective
receiving elements 61a to 61e may be made different, and a special process is not necessary for
manufacturing the receiving unit 60. The manufacturing cost of the receiving unit 60 can be
reduced compared to the technique of Patent Document 1 that requires a manufacturing process.
[0132]
Further, according to the third embodiment, only the thicknesses Ha to He of the respective
receiving elements 61a to 61e may be made different, and only a very small gap to the extent
that vibration is not directly transmitted between the respective receiving elements 61a to 61e.
As compared with the technique of Patent Document 1 in which the overall size and weight
increase by the volume and weight of the filler, the receiving unit 60 can be made smaller and
lighter.
[0133]
Furthermore, in the third embodiment, as in the second embodiment, since the entire shape of
the receiving unit 60 is a flat rectangular shape, both ends in the longitudinal direction of each of
the receiving elements 61a to 61e are compared to the first embodiment. Since it becomes
possible to simplify the fixed structure of the part and the fabrication of the receiving part 60
becomes easy, the manufacturing cost of the receiving part 60 can be further reduced.
04-05-2019
32
[0134]
And in 3rd Embodiment, since the width of receiving part 60 becomes small compared with 2nd
embodiment, and the plane size which looked at receiving part 60 from the upper part becomes
small, receiving part 60 is not shown in a package (illustration abbreviation). It is possible to
reduce the volume when housed, and the receiving unit 60 can be further reduced in size and
weight.
[0135]
[3-4] FIG. 11 is a perspective view showing a first modified example of the third embodiment.
FIG. 12 is a perspective view showing a second modification of the third embodiment.
In the example shown in FIG. 10, the receiving surfaces S of the receiving elements 61a to 61e
are arranged to be flush with one another.
However, as in the first modified example shown in FIG. 11, the back surfaces of the receiving
surfaces S of the receiving elements 61a to 61e may be arranged to be flush.
Further, as in the second modified example shown in FIG. 12, both the receiving surface S of each
of the receiving elements 61 a to 61 e and the back surface thereof may be appropriately
arranged and arranged without being flush.
[0136]
However, when the receiving surfaces S of the receiving elements 61a to 61e are flush with each
other, the measurement accuracy of the position and distance of the detection target can be
enhanced.
Further, as in the first modification or the second modification, when the receiving surfaces S of
the receiving elements 61a to 61e are not flush with each other, the timing of the ultrasonic
waves received by the receiving elements 61a to 61e is Deviations must be corrected, and
04-05-2019
33
complex signal processing circuitry is required to process the electrical signals generated by the
receiver 60.
On the other hand, if the receiving surface S of each of the receiving elements 61a to 61e is
made flush, there is no need to correct the timing shift of the ultrasonic waves received by each
of the receiving elements 61a to 61e. Signal processing circuits for processing signals can be
simplified.
[0137]
[3-5] FIG. 13 is a perspective view showing a third modification of the third embodiment.
In the example shown in FIG. 10, the receiving elements 61a to 61e are arranged in the order of
thickness H.
However, as in the third modified example shown in FIG. 13, the receiving elements 61 a to 61 e
may be appropriately arranged and arranged regardless of the thickness H.
[0138]
When vibration transmission between the receiving elements 61a to 61e is completely cut off,
the acoustic crosstalk reduction effect in the example shown in FIG. 10 and the third modification
is the same. However, in practice, the vibration transmission between the receiving elements 61a
to 61e can not be completely cut off, so the vibration transmission can reduce the acoustic
crosstalk in the example shown in FIG. 10 and the third modification. There are some differences.
[0139]
Fourth Embodiment FIG. 14 is a perspective view of a receiver 70 of an ultrasonic sensor
according to a fourth embodiment. The receiving unit 70 includes nine receiving elements
(conversion means) 71a to 71i. The flat rectangular receiving elements 71a to 71i face the
04-05-2019
34
ultrasonic wave receiving surfaces S in the same direction, and are arranged almost without gaps,
so that the receiving surfaces S are flush with each other in the vertical and horizontal directions
on the same plane. They are two-dimensionally arranged, and their length, width and thickness
are formed to different dimensions.
[0140]
And both ends in the length direction or width direction of each of the receiving elements 71a to
71i are fixed to a fixed member (not shown) so that they can not vibrate. The receiving unit 70
may be manufactured by any method. For example, the receiving elements 71a to 71i
manufactured separately may be assembled, and integrally formed on a semiconductor substrate
using MEMS technology. It is also good. The structures of the receiving elements 71a to 71i are
the same as the receiving elements 11a to 11e of the first embodiment.
[0141]
[Operation and Effect of Fourth Embodiment] In the fourth embodiment, the lengths, widths, and
thicknesses of the first to third embodiments are set so that the primary resonance frequencies
of the receiving elements 71a to 71i have different values. If it sets suitably similarly to these, the
effect | action and effect similar to said [1-1]-[1-4] of 1st Embodiment will be acquired. In
addition, according to the fourth embodiment, by arranging the receiving elements 71a to 71i in
two dimensions, it is possible to further enhance the measurement accuracy of the position and
distance of the detection target.
[0142]
[Another Embodiment] The present invention is not limited to the above embodiments, and may
be embodied as follows, and even in that case, the operation and effect equal to or more than the
above embodiments. You can get
[0143]
[Other Example 1] The receiving units 10, 50, and 60 in the first to third embodiments are
configured of five receiving elements 11a to 11e, 51a to 51e, and 61a to 61e, and the receiving
unit 70 in the fourth embodiment is The number of receiving elements constituting the receiving
04-05-2019
35
unit corresponds to the measurement accuracy of the position and distance of the detection
object, and the accuracy is increased as the number of receiving elements is increased. can do.
Therefore, the number of receiving elements and the arrangement interval may be set by
experimentally finding an optimum value by cut-and-try according to the required measurement
accuracy.
[0144]
[Another Example 2] From Equation 1, the displacement x at the frequency f (= f1 ± 7 × f1 / Q)
shifted by ± 7 × f1 / Q from the primary resonance frequency f1 shown in FIG. About 1/100 of
the
[0145]
Therefore, in the first embodiment, with respect to the receiving element 11a of the primary
resonance frequency F1a, the primary resonance frequencies of the receiving elements 11b and
11d arranged side by side on both sides thereof are frequency F1b and F1d (= F1a ± 7 ×,
respectively). If F1a / Q) is set, the influence of the respective receiving elements 11a, 11b, 11d
on each other's vibration can be reduced to about 1/100.
That is, the primary resonance frequency of the receiving element 11b may be set to F1b (= F1a
+ 7 × F1a / Q). Further, the primary resonance frequency of the receiving element 11d may be
set to F1d (= F1a-7 × F1a / Q).
[0146]
Similarly, for the primary resonance frequency F1b (= F1a + 7 × F1a / Q) of the reception
element 11b, the primary resonance frequency of the reception element 11c arranged in parallel
to the reception element 11b is F1c (= F1b + 7 × F1b / Q) It should be set to Further, for the
primary resonance frequency F1d (= F1a-7 × F1a / Q) of the reception element 11d, the primary
resonance frequency of the reception element 11e arranged in parallel to the reception element
11d is F1e (= F1d-7 × F1d) It should be set to / Q).
04-05-2019
36
[0147]
As described above, if the primary resonance frequencies F1a to F1e of the receiving elements
11a to 11e are set to different values, the influence of the respective receiving elements 11a to
11e on each other is almost negligible, about 1/100. While it is inferior to 1/256 of the first
embodiment, almost the same effect can be obtained.
[0148]
That is, since the difference between the primary resonance frequencies F1a to F1e of the
receiving elements 11a to 11e increases as the coefficient n in Formula 30 is set to a larger
value, the receiving elements 11a to 11e are affected by each other's vibration. It becomes
smaller, and the measurement accuracy of the position and distance of the detection object can
be increased.
However, as the coefficient n in Equation 30 is set to a larger value, the difference in length L
between the receiving elements 11a to 11e increases, and the overall size and weight of the
receiving unit 10 also increase.
[0149]
Therefore, the value of the coefficient n may be experimentally found and set by cut and try
according to the required measurement accuracy, but as in the first embodiment and the
example, n = 8 Alternatively, setting n = 7 can provide a practically sufficient effect.
[0150]
f = f1 ± n × f1 / Q (Equation 30)
[0151]
In the second to fourth embodiments as well, as in the first embodiment, the value of the
coefficient n may be appropriately set according to the required measurement accuracy, but n =
8 or n = 7 may be set. If it is practical, sufficient effects can be obtained.
[0152]
04-05-2019
37
[Other Example 3] The receiving elements 11a to 11e, 51a to 51e, and 61a to 61e constituting
the receiving units 10, 50, and 60 of the first to third embodiments are fixed so that both ends in
the length direction can not vibrate. ing.
However, only one end in the length direction of each of the receiving elements 11a to 11e, 51a
to 51e, and 61a to 61e may be fixed so as not to vibrate.
Moreover, as for the receiving elements 71a-71i which comprise the receiving part 70 of 4th
Embodiment, the both ends of the length direction or the width direction are being fixed so that
vibration is impossible.
However, only one end in the length direction or the width direction of each of the receiving
elements 71a to 71i may be fixed so as not to vibrate.
[0153]
[Another example 4] The receiving surface S of each of the receiving elements 11a to 11e, 51a to
51e, 61a to 61e, 71a to 71i constituting the receiving units 10, 50, 70 according to the first,
second, and fourth embodiments It is arranged to be flush. However, as for the respective
receiving elements constituting the receiving units 10, 50, 70, the receiving surface S is flush as
in the first modification (FIG. 11) or the second modification (FIG. 12) of the third embodiment.
You may arrange side by side suitably, without using it.
[0154]
[Other Example 5] Although the above embodiments are applied to the receiving unit of the
ultrasonic sensor, the present invention may be applied to a transmitting unit of the ultrasonic
sensor that converts an electric signal into an ultrasonic wave and transmits the ultrasonic wave.
. That is, the receiving elements 11a to 11e, 51a to 51e, 61a to 61e, and 71a to 71i of the
receiving units 10, 50, 60, and 70 may function as transmitting elements (conversion means) of
the transmitting unit. In this case, the receiving surface S of each receiving element is a
transmitting surface for transmitting an ultrasonic wave from the transmitting element.
04-05-2019
38
[0155]
For example, in the case where each transmitting element is the first structural example
(piezoelectric type) shown in FIG. 2, the composite piezoelectric body 23 has a piezoelectric
effect in accordance with the electrical signal applied to the lower electrode 21 and the
electrodes 22a to 22e. As a result, ultrasonic waves are emitted from the electrodes 22a to 22e
by vibration. In addition, when each transmitting element is made the second structural example
(piezoelectric type) shown in FIG. 3, the dielectric layer 31 has a piezoelectric effect in
accordance with the electric signal applied to the lower electrode 21 and the electrodes 22a to
22e. As a result, ultrasonic waves are emitted from the electrodes 22a to 22e by vibration. In
addition, in the case of using the third structure example (capacitor type) shown in FIG. 4 as each
transmitting element, the lower electrode 21 and the electrodes 22a to 22e are selected
according to the electric signal applied to the lower electrode 21 and the electrodes 22a to 22e.
An electrostatic attractive force is generated between it and 22e, and the electrodes 22a to 22e
are vibrated by the electrostatic attractive force to generate an ultrasonic wave.
[0156]
As described above, when each receiving element of the receiving unit is made to function as
each transmitting element of the transmitting unit, the primary resonance frequency of each
transmitting element is set to a different value, so that each transmitting element transmits
Ultrasonic waves can be made into chords.
[0157]
1st Embodiment which implemented this invention The perspective view of the receiving part 10
of the ultrasonic sensor in 1st Embodiment.
FIG. 2 is a schematic vertical cross-sectional view showing a first structural example of the
receiving elements 11a, 11b, and 11d that constitute the receiving unit 10. The schematic
longitudinal cross-sectional view which shows the 2nd structural example of receiving element
11a, 11b, 11d which comprises the receiving part 10. FIG. The schematic longitudinal crosssectional view which shows the 3rd structural example of receiving element 11a, 11b, 11d which
comprises the receiving part 10. FIG. The characteristic view which shows the resonance
characteristic which is a relation of frequency f of a diaphragm to which both ends were fixed,
and displacement x of vibration. The perspective view which shows the 1st modification of 1st
Embodiment. The perspective view which shows the 2nd modification of 1st Embodiment. The
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perspective view of the receiving part 50 of the ultrasonic sensor in 2nd Embodiment which
actualized this invention. The perspective view which shows the modification of 2nd
Embodiment. The perspective view of the receiving part 60 of the ultrasonic sensor in 3rd
Embodiment which actualized this invention. The perspective view which shows the 1st
modification of 3rd Embodiment. The perspective view which shows the 2nd modification of 3rd
Embodiment. The perspective view which shows the 3rd modification of 3rd Embodiment. The
perspective view of the receiving part 70 of the ultrasonic sensor in 4th Embodiment which
actualized this invention.
Explanation of sign
[0158]
10, 50, 60, 70: Reception unit or transmission unit of ultrasonic sensor 11a to 11e, 51a to 51e,
61a to 61e, 71a to 71i: Reception element or transmission element as conversion means S:
Reception surface or transmission surface
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