JP5950742B2 - Ultrasonic transducer - Google Patents

Description

The present invention relates to an aerial ultrasonic transducer that performs transmission and reception using ultrasonic waves.

Ultrasonic transducers are used as sensors that detect the distance between a vehicle and surrounding obstacles. At this time, the ultrasonic handset is often used by being embedded in a bumper or the like of a car, and depending on the mounting position, a back sensor that detects an obstacle behind the car or a corner sensor that detects an obstacle at a corner. is called.

For the obstacle detection using this ultrasonic handset, a material or a mechanism for converting vibrations and electric signals existing inside the ultrasonic handset is used. Using this, an ultrasonic signal corresponding to the input pulse burst electric signal is oscillated from the ultrasonic transducer by inputting the pulse burst electric signal to the ultrasonic transducer, and the generated ultrasonic signal is an obstacle. After reaching the obstacle, a part of the reflected ultrasonic signal returns to the same ultrasonic transducer. The ultrasonic transducer detects the obstacle by receiving the reflected signal, and measures the distance between the vehicle and the obstacle by using the time difference between transmission and reception.

FIG. 1 shows a schematic longitudinal sectional view of an ultrasonic transducer according to a conventional embodiment. FIG. 2 shows a schematic top view and a cross-sectional view of a bottomed cylindrical case in an ultrasonic transducer according to a conventional embodiment. In FIG. 1, a piezoelectric element 1 is bonded to the inner bottom surface of a bottomed cylindrical case 2 made of an aluminum material or the like, and a unimorph vibrator is configured. The piezoelectric element 1 is made of an insulator having piezoelectricity, and two independent electrodes are formed on the surface by a conductive material such as silver.

One electrode on the surface of the piezoelectric element 1 existing on the opposite surface of the piezoelectric element 1 and the bottomed cylindrical case 2 on the bonding surface side is electrically connected to the input / output lead 5a by soldering or the like. The input / output lead 5b is electrically connected to the bottomed cylindrical case 2 or the other electrode on the surface of the piezoelectric element 1 by soldering or the like. Here, the bonding surface side of the piezoelectric element 1 with the bottomed cylindrical case 2 and the bottomed cylindrical case 2 are electrically connected.

The input / output leads 5a and 5b are respectively soldered to the wire 6 of the connector with the PVC coated wire. A sound absorbing material 3 made of a silicone foam or the like is installed on the upper surface of the piezoelectric element 1, and a filler 8 made of an elastic material such as a silicone material or a urethane material is placed in a hole formed in the sound absorbing material 3 for passing the input / output lead 5a. The bottomed cylindrical case 2 is filled with a sealing agent 4 made of an elastic material such as a silicone material or a urethane material. All of the side openings 9 of the bottomed cylindrical case 2 need to be filled with a filler 7 made of a silicone material, a urethane material or the like.

In the ultrasonic transducer according to the conventional embodiment, the inside of the bottomed cylindrical case is rectangular, the wide side is the horizontal direction, the narrow side is the vertical direction, and the horizontal directivity is wide as the required directivity, the vertical direction Need to be narrow.
When installed in a vehicle, etc., it transmits ultrasonic waves that spread in the horizontal direction parallel to the road surface, detects obstacles in a wide area, and transmits ultrasonic waves that suppress spread in the direction perpendicular to the road surface. This is to suppress erroneous detection such as reflection of ultrasonic waves from the road surface.

In order to realize this directivity, an invention has been made in which the directivity in the vertical direction is narrowed by providing an opening on the side surface of the rectangular narrow side inside the bottomed cylindrical case as shown in FIG. . The ultrasonic transmitter according to the present invention has begun to be applied as a use with a long detection distance as a market trend.

JP 2001-13239 A

In conventional ultrasonic transducers, that is, in the aerial ultrasonic transducer in which the inside of the bottomed cylindrical case is provided with an opening in the center of the side surface on the narrow side that is circular or rectangular, the horizontal directivity is the vehicle There is a problem that the detection range extends beyond the width and becomes more than necessary.

A unimorph vibrator is constructed by laminating a piezoelectric element inside the bottom surface of a bottomed cylindrical case, and an ultrasonic transducer that transmits and receives ultrasonic waves on the case outer surface of this vibrating body has a bottomed cylindrical shape. Openings are provided at two locations on the side wall of the case, and the shape of the openings is provided so as to be axisymmetric with respect to the central axis of the bottomed cylindrical case.

Since the shape of the opening is axisymmetric with respect to the central axis of the case, the horizontal directivity is decentered and the detection range can be prevented from protruding beyond the vehicle width.

According to a first aspect of the present invention, horizontal directivity is provided by providing the two openings so that the opening is axisymmetric with respect to the central axis of the bottomed cylindrical case. Eccentric.

According to a second aspect of the present invention, the opening in the first aspect has a rectangular shape or an elliptical shape, and further, the direction of the long side or long axis of the opening is inclined with respect to the bottom surface of the case. On the vibration surface, the closer to the opening, the lower the rigidity. For this reason, directivity is decentered in a direction close to the vibration surface in the opening.
However, the eccentricity of directivity is lost as the position near the vibration surface of the opening becomes higher than the inner bottom surface of the bottomed cylindrical case.

In the inclination of the opening with respect to the bottom surface of the bottomed cylindrical case, the eccentricity of directivity is noticeable in the range of 5 ° to 20 °. Further, as the angle approaches 90 °, the rigidity is likely to be lowered only at a position near the vibration surface of the bottomed cylindrical case in the opening, and the rigidity of the entire vibration surface is increased. For this reason, the vibration of the vibration surface immediately below the opening becomes gradually difficult, and the directivity shown by the bottomed cylindrical case when no opening is provided is gradually changed, making it difficult to observe the eccentricity.

According to a third aspect of the present invention, the opening in the first aspect has an arc shape or a polygonal shape, and is perpendicular to the bottom surface of the bottomed cylindrical case and a straight line passing through the centroid of the opening shape. It is characterized in that the opening shape is provided so as to be non-axisymmetric.

The effect of this invention is that, as in the second invention, the rigidity distribution of the vibration surface directly under the opening can be controlled by forming a portion near and far from the vibration surface in the opening. In addition, by making the opening in an arc shape or a polygonal shape, it becomes possible to design more freely than a rectangular shape in which the distance between the vibration surface and the opening can be changed only linearly. Furthermore, the width of the opening in the direction perpendicular to the vibration surface has less influence on directivity compared to the width in the direction parallel to the vibration surface, and the strength of the ultrasonic handset decreases as the area of the opening increases. In addition, an arc shape or a polygonal shape, which can easily reduce the area of the opening, is more advantageous than the elliptical shape.
Next, the purpose of making the opening shape non-symmetrical with respect to a straight line passing through the centroid of the opening shape and perpendicular to the bottom surface of the bottomed cylindrical case is to specify the rigidity of the vibration surface immediately below each opening. This is because the directivity is decentered in that direction.

According to a fourth aspect of the present invention,
The opening in the first invention is rectangular or elliptical,
Further, by setting the angle φ between the central axes of the openings in the plane parallel to the bottom surface of the bottomed cylindrical case to be in the range of 60 ° ≦ φ ≦ 150 degrees, the direction of the openings where the rigidity of the vibration surface is reduced Vibrations are easy to propagate to. For this reason, directivity is decentered in the direction in which the opening exists.
However, as the position of the lower part of the opening becomes higher than the inner bottom of the bottomed cylindrical case, the rigidity of the vibration surface immediately below the opening increases, and the propagation of vibration in the direction of the opening is suppressed, resulting in an eccentric effect. Will be lost.

According to a fifth aspect of the present invention, by providing the bottomed cylindrical case with the opening shape and arrangement according to at least one of the first to fourth aspects of the invention, directivity eccentricity can be easily achieved. It becomes possible to control.

Schematic longitudinal sectional view of an ultrasonic transducer according to a conventional embodiment Schematic and cross-sectional view of a bottomed cylindrical case according to a conventional embodiment 1 is a schematic longitudinal sectional view of an ultrasonic transducer according to an embodiment of the present invention. Schematic of a bottomed cylindrical case with an inclined angle at the opening Comparison of horizontal directivity between the conventional product and the case where the opening is provided with an inclination angle of 10 ° Relationship between the angle of inclination of the opening and the eccentricity of the horizontal directivity Schematic of bottomed cylindrical case with arc-shaped opening Schematic of bottomed cylindrical case with polygonal openings Schematic side view of bottomed cylindrical case with non-parallel crossing angle between central axes of openings Comparison of horizontal orientation between conventional product and 120 ° crossing angle Relationship between crossing angle between central axis of opening and eccentricity of horizontal directivity Schematic diagram of detection range of back sensor using ultrasonic transmitter / receiver related to conventional embodiment Schematic diagram of detection range of back sensor using ultrasonic transmitter / receiver according to the embodiment of the present invention

FIG. 3 is a schematic longitudinal sectional view of an ultrasonic transducer according to the embodiment of the present invention. In FIG. 3, a piezoelectric element 1 is bonded to the inner bottom surface of a bottomed cylindrical case 2 made of an aluminum material or the like to form a unimorph vibrator. The piezoelectric element 1 is made of an insulator having piezoelectricity, and two independent electrodes are formed on the surface by a conductive material such as silver.

One electrode on the surface of the piezoelectric element 1 existing on the opposite surface of the piezoelectric element 1 and the bottomed cylindrical case 2 on the bonding surface side is electrically connected to the input / output lead 5a by soldering or the like.
The input / output lead 5b is electrically connected to the bottomed cylindrical case 2 or the other electrode on the surface of the piezoelectric element 1 by soldering or the like. Here, the bonding surface side of the piezoelectric element 1 with the bottomed cylindrical case 2 and the bottomed cylindrical case 2 are electrically connected. The input / output leads 5a and 5b are respectively soldered to the wire 6 of the connector with the PVC coated wire. A sound absorbing material 3 made of a silicone foam or the like is installed on the upper surface of the piezoelectric element 1, and a filler 8 made of an elastic material such as a silicone material or a urethane material is placed in a hole formed in the sound absorbing material 3 for passing the input / output lead 5a. The bottomed cylindrical case 2 is filled with a sealing agent 4 made of an elastic material such as a silicone material or a urethane material. All of the side openings 9 of the bottomed cylindrical case 2 need to be filled with a filler 7 made of a silicone material, a urethane material or the like.

FIG. 4 is a schematic side view of a bottomed cylindrical case according to the embodiment of the present invention. In FIG. 4, two openings Oa and Ob are provided on the side surface of a bottomed cylindrical case made of an aluminum material or the like. For example, the shapes of the openings Oa and Ob shown in FIG. 4 are both rectangles having long sides and short sides and R shapes at the four corners. The opening Oa and the opening Ob are provided obliquely (with an inclination angle θ) with respect to the bottom surface V of the bottomed cylindrical case 2. In addition, the opening Oa and the opening Ob are provided so that portions close to the vibration surfaces of the opening Oa and the opening Ob are in contact with the inner bottom surface of the bottomed cylindrical case. Here, the shape of the opening Oa and the opening Ob is mirror-symmetrical with respect to the cross section A passing through the central axis P1 passing through the centroid P of the bottom surface V so that the horizontal directionality eccentricity is maximized. Designed to be However, if the eccentricity of directivity in the other direction is necessary, the inclination angles of the opening Oa and the opening Ob may not necessarily be the same, and the shape of the opening Oa and the opening Ob is also relative to the cross section A. It does not have to be mirror-symmetric. The opening may be separated from the inner bottom surface of the bottomed cylindrical case made of an aluminum material or the like, and the opening may completely reach the vicinity of the upper surface of the case.

FIG. 5 is a result of comparing the directivity in the horizontal direction when the inclination angle of the opening is θ = 10 ° using the bottomed cylindrical case of FIG. 4 and when there is no conventional inclination. The directivity was measured as follows. A φ50 cm pole is installed at a position 60 cm from the design surface of the ultrasonic transducer. Reflection sensitivity was measured by moving the pole position concentrically to a position perpendicular to the design surface of the ultrasonic transmitter / receiver, that is, when the pole is in front of the ultrasonic transmitter / receiver at 90 °. Here, let the direction of the intersection line of the bottom face V and the cross section A be a horizontal direction of directivity. Only when there is an inclination, the eccentricity of directivity is seen in the direction in which the distance between the bottom surface of the bottomed cylindrical case and the opening is short in the horizontal direction. The directivity was measured as follows. A φ50 cm pole is installed at a position 60 cm from the design surface of the ultrasonic transducer. The reflection sensitivity was measured by moving the pole position concentrically to a position perpendicular to the design surface of the ultrasonic transmitter / receiver, that is, when the pole is in front of the ultrasonic transmitter / receiver at 90 °.

FIG. 6 shows the degree of eccentricity when the inclination angle of the opening is changed between 0 ° and 25 ° using the bottomed cylindrical case of FIG. The directivity is measured by the above method, and the position (angle) of the pole where the reflection sensitivity is maximized is confirmed. The vertical axis of FIG. 6 indicates a value of (90 °) − (angle at which reflection sensitivity is maximum). If the reflection sensitivity is maximized when the pole is at a position of 90 ° (that is, in front of the ultrasonic transducer of the pole), the angle at which the reflection sensitivity is maximized is 90 °. The value on the vertical axis is 0. When the directivity is decentered and the reflection sensitivity is maximized at angles other than 90 °, the value on the vertical axis increases. An eccentricity of 10 ° or more, which is considered to be practically effective, can be obtained when the ultrasonic transducer is designed with the range of the inclination angle θ of the opening being 5 ° ≦ θ ≦ 20 °.

From the result of FIG. 6, it can be understood that the rigidity of the nearby vibration surface changes depending on the shape of the opening, and the eccentricity of directivity is generated by biasing the distribution of this rigidity in a specific direction. For this reason, directivity can be similarly decentered by using arc-shaped or polygonal openings as shown in FIGS.

The shape of the opening shown in FIG. 7 has two or more arcs, and both ends of the arc are connected.

The shape of the opening shown in FIG. 8 is a polygon, and each corner is a curved surface (R surface).

FIG. 9: represents the schematic side view of another bottomed cylindrical case in connection with embodiment of this invention. In FIG. 9, the bottomed cylindrical case made of aluminum or the like intersects at an intersecting angle φ where Pa and Pb are non-parallel when the central axes of the openings Oa and Ob are Pa and Pb, respectively. An opening was provided. At this time, the central axis of the bottomed cylindrical case is indicated by P1. The opening may be separated from the bottom surface of the bottomed cylindrical case made of an aluminum material or the like, and the opening may completely reach the upper surface of the case. Here, in order to make the direction of the angle of φ / 2 the horizontal direction and increase the eccentricity of the horizontal directivity, the shape of the opening Oa and the opening Ob and the height from the bottom surface of the bottomed cylindrical case are equal. An opening was provided so as to be. However, when the directivity in different directions is decentered, the shapes of the opening Oa and the opening Ob and the height from the bottom surface of the bottomed cylindrical case do not have to be equal.

FIG. 10 shows a case where the bottomed cylindrical case of FIG. 9 with an intersection angle of φ = 120 ° is used, and a conventional φ = 180 ° and two opening shapes with respect to the central axis of the bottomed cylindrical case. It is the result of having compared horizontal directivity with the case where it is 2 times symmetrical.

FIG. 11 shows the directivity obtained by measuring the degree of eccentricity when the crossing angle φ between the central axes of the openings is changed between 0 ° ≦ φ ≦ 180 ° using the bottomed cylindrical case of FIG. This is a result of plotting the angle of the maximum reflection sensitivity by an angle subtracted from 90 °. An eccentricity of 10 ° or more, which is considered to be practically effective, can be obtained when the ultrasonic transducer is designed with the range of the crossing angle φ being 60 ° ≦ φ ≦ 150 °. In FIG. 11, the value of φ = 0 ° is obtained by providing only one opening. In addition, the bottomed cylindrical case used in the measurement of FIG. 11 is designed so that the central axes of the openings intersect with each other on the central axis of the bottomed cylindrical case, so that no eccentricity occurs at φ = 180 °. . However, the effect of the present invention can be obtained in the same manner even if the central axes of the openings intersect each other except on the central axis of the bottomed cylindrical case.

FIG. 12 is a schematic diagram of the detection range of the back sensor using the ultrasonic transceiver according to the conventional embodiment, and FIG. 13 is an ultrasonic transceiver according to the conventional embodiment and the ultrasonic according to the embodiment of the present invention. The comparison schematic diagram of the detection range of a back sensor using a sound wave transceiver is shown. As shown in FIG. 1, the back sensor using the ultrasonic transmitter / receiver according to the conventional embodiment has a detection range in the horizontal direction that is too wide and wider than the vehicle width, and has detected an extra portion. In contrast, in the back sensor using each ultrasonic transceiver according to the embodiment of the present invention, the detection range does not protrude beyond the vehicle width by decentering the horizontal directivity toward the inside of the vehicle. Therefore, the intended ideal detection range can be obtained.

DESCRIPTION OF SYMBOLS 1 Acoustic matching layer 2 Piezoelectric element 3 Sound-absorbing material 4 Sealing material 5 Cylindrical case having openings at both ends 5a Input / output leads 5b Input / output leads V Bottom surface P Bottom centered cylindrical case bottom centroid P1 Bottomed cylindrical case Central Axis Pa Opening Pb Opening Oa Central Axis of Opening Pa Ob Central Axis of Opening Pb θ Tilt Angle of Opening φ Crossing Angle of Oa and Ob

Claims (5)

A piezoelectric element is attached inside the bottom of the bottomed cylindrical case to form a unimorph vibrator,
In the ultrasonic transmitter / receiver for air that transmits and receives ultrasonic waves by vibration of the unimorph vibrator,
There are two openings on the side of the bottomed cylindrical case,
An aerial vehicle characterized in that the shape of the opening is axisymmetric with respect to a central axis perpendicular to the bottom surface of the bottomed cylindrical case and passing through the centroid of the bottom surface of the bottomed cylindrical case Sonic transducer. The aerial ultrasonic transducer according to claim 1,
The opening has a rectangular or elliptical shape,
Furthermore, the ultrasonic transducer for the air, characterized in that the direction of the long side or long axis of the opening is inclined within a range of 5 ° to 20 ° with respect to the bottom surface of the case. The aerial ultrasonic transducer according to claim 1,
An aerial ultrasonic transducer characterized in that the opening has an arc shape or a polygonal shape which is perpendicular to the bottom surface of the bottomed cylindrical case and is axisymmetric with respect to a straight line passing through the centroid of the opening shape. . The aerial ultrasonic transducer according to claim 1,
The opening is rectangular or elliptical,
And the angle between each central axis of the said opening part exists in the range of 60 degrees-150 degrees, The ultrasonic transmitter / receiver for the air characterized by the above-mentioned.  An aerial ultrasonic transducer combining the shape of the opening according to any one of claims 1 to 4 and the characteristics of the arrangement of the openings.

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