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JPH02202798

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DESCRIPTION JPH02202798
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic transducer for transmitting and receiving ultrasonic waves. 2. Description of the
Related Art Conventionally, this type of ultrasonic transducer is used for obstacle detection and
distance measurement. However, in the obstacle detection device using this ultrasonic
transducer, when the installation height of the ultrasonic transducer is within the detection
distance setting range, the floor surface is detected, and the obstacle is detected regardless of the
presence or absence of the obstacle. There is a possibility that it may be misjudged as yes. In this
case, it is effective to lower the sound pressure level in the direction of the floor surface 90 °
downward in the directivity characteristics of the ultrasonic transducer. One of the means is to
provide a horn portion vertically elongated in the front direction of the ultrasonic transducer. By
this structure, the directivity in the vertical direction becomes narrower than in the horizontal
direction, and the sound pressure level in the vertical direction, that is, the floor direction
decreases, so that the obstacle detection device does not make an erroneous determination.
[Problems to be Solved by the Invention] However, in the case where the horn portion whose
shape is changed as in the longitudinal direction is provided, when the directivity in a
predetermined direction is further narrowed, the shape is restricted by the shape of the horn
portion. There is a problem that the directivity in the predetermined direction can not be freely
narrowed. The present invention has been made in view of the above problems, and it is an
object of the present invention to provide an ultrasonic transducer capable of further narrowing
the directivity in the predetermined direction without changing the shape or the like of the horn
portion. It is. [Means for Solving the Problems] In order to achieve the above object, the present
invention provides a horn portion on the front surface of an ultrasonic transducer, and also
suppresses the directivity in a predetermined direction at this horn opening It is characterized in
that the directivity adjusting unit is disposed in a direction opposite to the predetermined
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direction with respect to the center position of the unit. [Operation] In the ultrasonic transducer
having the above configuration, the directivity adjusting unit is arranged such that the ultrasonic
wave emitted from the ultrasonic transducer or the ultrasonic wave incident from the outside is
shifted from the center position of the horn opening. The sound pressure level in the direction
opposite to the direction shifted from the center position is reduced to change the directivity of
the ultrasonic transducer. Embodiments of the present invention will be described below with
reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of the present
invention, wherein (a) is a front view, and (b) is an AA sectional view of the one shown in FIG. 1
(a). In FIG. 1, reference numeral 11 denotes an ultrasonic transducer which radiates an applied
electric signal to the outside as an ultrasonic wave (40 KHz) by mechanical vibration and
converts the reflected wave returned back to an electric signal. Reference numeral 12 denotes a
rubber cushion for holding the ultrasonic transducer 11 therein, and reference numeral 13
denotes a housing whose opening 13a has a horn shape.
The opening 13a of the housing 13 is provided with flat directivity adjusting parts 18a and 18b.
Furthermore, 14 is a retainer for fixing the ultrasonic transducer 11 and cushion 12 to the
housing 13. Reference numeral 15 denotes a circuit board, which includes a transmission signal
booster circuit and a reception signal amplifier circuit. A cover 17 is a signal extraction wire from
the sensor 16. Fig. 2 is a detailed view of the housing portion of the first embodiment, where (a)
is a front view, (b) is a cross-sectional view to that shown in (a) but (C) is a diagram (a) It is BB
sectional drawing of what is shown to. The directivity adjusting portions 18a and 18b are the
same in material and shape, and are flat plates of 17 mm × 3 mm × 1 mm. In addition, the
opening 13a has a short diameter of 10+! + M, with a major diameter gradually changing from
10 mm to a major circle of 18 cabinets, it is vertically elongated in the vertical direction. In FIG.
2, a is 17 cylinders, b is 3 cylinders, and L is 1 m + n. 2 is 5 mm, d is 3.5 mm, and dz is 2 dishes.
Now, the ultrasonic transducer according to the first embodiment is installed on the floor surface
F as shown in FIG. 3 (a). At this time, the axis of the opening 13a in the longitudinal direction is
set so as to be perpendicular to the floor surface. FIG. 3 [presence] is the figure seen from the
upper direction in said installation condition. In FIG. 3 (a), with the center C of the outer end face
of the opening as the origin, the sound pressure from the ultrasonic transducer at a fixed
distance at each angle, or from the sounding body placed at a fixed distance at each angle The
vertical directivity is the measurement of the output voltage of the ultrasonic transducer with
respect to the transmission sound wave of. Also, the horizontal directivity is the one measured
similarly in FIG. FIG. 4 shows measured data of vertical directivity and horizontal directivity of
Ji911 in the first embodiment. Curves 41 and 43 are directivity characteristics in the horizontal
and vertical directions, respectively, of the first embodiment, and curves 42 and 44 are
directivity characteristics in the horizontal and vertical directions of the conventional ultrasonic
transducer. The conventional shape is obtained by removing the directivity adjusting portions
18a and 18b in FIG. 1, and other configurations and dimensions are the same. As apparent from
FIG. 4, the horizontal directivity maintains the conventional performance, while the sound
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pressure level drops significantly outside 40 ° in the vertical direction. In the lower 90 °
direction of the ultrasonic transducer, the effect of 1 ldll is seen in the upper 90 ° direction.
Next, FIG. 5 is a detailed view of the housing portion of the ultrasonic transducer according to the
second embodiment of the present invention, where (a) is a front view and (b) is an AA sectional
view of the one shown in FIG. It is.
This is obtained by removing the directivity adjustment unit 18b of the first embodiment. The
vertical directivity and horizontal directivity measured as shown in FIG. 3 and measured are
shown in FIG. In FIG. 6, a curve 63 is the second embodiment and a curve 64 is the vertical
directivity characteristic of the conventional ultrasonic transducer. The curve vA 61 is the second
embodiment, and the curve 62 is the horizontal directivity characteristic of the conventional
ultrasonic transducer. As seen from FIG. 6, unlike the first embodiment, while maintaining the
same level in the upper direction as in the conventional case, the reduction effect is seen to be
greater than around 30 ° with respect to the lower direction. There is a reduction effect of
about 8 dB. Also, the horizontal directivity remains at the same level as before. Next, the shape of
the housing portion of the third embodiment is shown in FIGS. 7 (a) and 7 (b). FIG. 7 (a) is a
sectional view taken along the line A-A of the first embodiment shown in FIG. 2 (b), in which the
directivity adjusting portions 18a and 18b are inclined by 20 °. 7 (b) is a detailed view of the
directivity adjustment unit of FIG. 7 (a), b. t, z and dz are the same as in the first embodiment.
FIG. 8 shows the vertical directivity of the third embodiment. Curve 81 is the characteristic of the
third embodiment, and curve 82 is the characteristic of the prior art. As can be seen in
comparison with the conventional characteristics, the vertical directivity is narrowed particularly
in the downward direction. FIG. 9 is a detailed view of the housing part of the fourth
embodiment, wherein (a) is a front view, (b) is a cross-sectional view taken along the line A-A of
FIG. It is BB sectional drawing of things. As shown in FIG. 9 (C), the directivity adjusting parts 18a
and 18b of the first embodiment are modified by cutting both side parts thereof. In the figure, a
is 20 mm, and the other structure is the same as that of the first embodiment. Both the vertical
directivity and the horizontal directivity measured are equivalent to the result of the first
embodiment shown in FIG. FIG. 10 is a detailed view of the housing part of the fifth embodiment,
where (a) is a front view, and (b) is a sectional view taken along the line A-A of FIG. It is a BB
sectional view. This is a modification of the depth dimension of the directivity adjusting portion
1Ba of the second embodiment shown in FIG. 5, and the depth is shortened by IIIIffl, and the
protrusion of the directivity adjusting portion is eliminated from the end face of the housing and
integrated with the housing There is. The measured directivity in the vertical and horizontal
directions is equivalent to the result of the second embodiment shown in FIG. Although the
directivity in the vertical direction is changed in the various embodiments described above, the
arrangement may be changed in accordance with the purpose of use to change the directivity in
the horizontal direction or the like.
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[Effects of the Invention] As described above, according to the present invention, the ultrasonic
wave emitted from the ultrasonic transducer or the outside is provided by disposing the
directivity adjusting portion at the horn opening portion offset from the center position thereof.
The sound pressure level of the ultrasonic wave incident from the side can be suppressed in the
direction opposite to the directivity adjustment unit with respect to the center position, and the
directivity of the ultrasonic transducer can be changed. By adjusting the arrangement position
arbitrarily, there is an excellent effect that an arbitrary detection area can be set.
[0002]
Brief description of the drawings
[0003]
1 (a) and 1 (b) are a front view and a side sectional view showing the first embodiment of the
present invention, and FIGS. 2 (a), 2 (b) and 2 (c) are respectively the housing portions of the first
embodiment. Front view, side sectional view, plan sectional view, FIG. 3 (a), (b) is a front view
showing the installation state of the ultrasonic transducer, a plan view, FIG. 4 is a directional
characteristic diagram of the first embodiment 5 (a) and 5 (b) are front and side sectional views
of the housing portion of the second embodiment, FIG. 6 is a directional characteristic diagram of
the second embodiment, and FIGS. 7 (a) and 7 (b). These are side sectional drawing of the
housing part of 3rd Example, detailed explanatory drawing of a directivity adjustment part, the
directivity characteristic view of 3rd Example, FIG. 8, (a), (b).
(C) is a front view, a side sectional view, and a plan sectional view of the housing portion of the
fourth embodiment; FIGS. 10 (a), (b) and (c) are front views of the housing portion of the fifth
embodiment; It is sectional drawing, a plane sectional view. 11: ultrasonic transducer, 12:
cushion, 13: housing, 13a: opening, 1B, a, 18b: directivity adjusting unit. (A) Fig. (B) (a'1 (C) Fig.
10 (b)
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