JPH0918995A - Ultrasonic sensor - Google Patents

Abstract

PURPOSE: To provide an ultrasonic sensor with a stable characteristic at a low cost. CONSTITUTION: An ultrasonic sensor 10 has external terminals 18a, 18b. Insert pieces 18a1, 18b1 are formed to one end of the external terminals 18a, 18b to clip a piezoelectric vibrator 12 in cooperation and connected electrically to the piezoelectric vibrator 12. Support pieces 18a2, 18b2 are formed integrally with the pieces 18a1, 18b1 to the other end of the external terminals 18a, 18b. The support pieces 18a2, 18b2 are inserted to paths 16a, 16b respectively and folded almost an L shape and fixed to the face of the base member 16 opposite to a piezoelectric vibrator 12. The support pieces 18a2, 18b2 of the external terminals 18a, 18b are used for input output terminals for the ultrasonic sensor 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic sensor,
In particular, the present invention relates to an ultrasonic sensor including a piezoelectric vibrator for electroacoustic conversion and used for obstacle detection and automatic doors, for example.

[0002]

2. Description of the Related Art FIG. 12 is a schematic sectional view showing an example of a conventional ultrasonic sensor which is the background of the present invention.
[Fig. 3] is a perspective view of a main part thereof. This ultrasonic sensor 1
It includes a piezoelectric vibrator 2 for electroacoustic conversion. Piezoelectric vibrator 2
Is formed, for example, by adhering a substantially circular piezoelectric body 2b made of, for example, a piezoelectric ceramic to one surface of a metal plate 2a having a substantially circular plane. A substantially conical cone 3 for transmitting and receiving ultrasonic waves is fixed to the other surface of the metal plate 2a of the piezoelectric vibrator 2.

The piezoelectric vibrator 2 is supported by a base member 4 having a substantially π-shaped cross section. The base member 4 is fixed to the vicinity of the node line of the piezoelectric vibrator 2 via a cushioning material 5. The cushioning material 5 is for absorbing vibration and is made of, for example, silicon rubber. In this specification, the node line refers to an imaginary line formed by connecting nodes generated on the circumference at a predetermined distance from the substantially central portion of the main surface of the piezoelectric vibrator 2.

Further, external terminals 6, 6'as input / output terminals are fixed to the base member 4. The external terminals 6 and 6'are formed of metal pins. External terminals 6, 6 '
The piezoelectric vibrator 2 and the piezoelectric vibrator 2 are electrically connected by lead wires 7 and 7 '. In this case, one end of the lead wire 7 is soldered to the metal plate 2a of the piezoelectric vibrator 2. Further, one end of the lead wire 7'is soldered to the piezoelectric body 2b of the piezoelectric vibrator 2 and further reinforced with epoxy resin or the like from above. Also, the other ends of the lead wires 7 and 7'are
As shown in FIG. 4, it passes through the recesses 4a and 4a 'of the base member 4, is wound around the external terminals 6 and 6', and is then soldered from above.

Further, the cover member 8 having a substantially U-shaped cross section is
It is fixed to the base member 4 so as to cover the piezoelectric vibrator 2 and the cone 3. The base member 4 and the cover member 8 form this conventional case.

[0006]

As described above, in the conventional ultrasonic sensor 1, the lead wires 7 and 7'are required to electrically connect the piezoelectric vibrator 2 and the external terminals 6 and 6 '. Is. However, the lead wires 7 and 7'are thin and difficult to handle. Further, in order to manufacture the conventional ultrasonic sensor 1, a step of soldering one end of the lead wires 7, 7'to the piezoelectric vibrator 2 and a portion soldered to the piezoelectric body 2b are reinforced with an epoxy resin. The number of steps is large because it requires a step, a step of winding the other ends of the lead wires 7, 7'on the external terminals 6, 6 ', and a step of soldering the wound wires on the external terminals 6, 6'. Therefore, in the conventional ultrasonic sensor 1, it is difficult to increase the production efficiency and it is also difficult to reduce the product cost.

Further, the lead wires 7, 6'are connected to the external terminals 6, 6 '.
Since tension is applied to the lead wires 7 and 7'when the 7'is wound, the lead wires 7'and the piezoelectric body 2b of the piezoelectric vibrator 2 must be soldered and then reinforced with epoxy resin or the like. There wasn't. Furthermore, the tension applied to the lead wires 7 and 7'suppresses the vibration of the piezoelectric vibrator 2 and the ultrasonic sensor 1
Became a factor that deteriorates the characteristics of.

Further, when silicone rubber is used as the cushioning material 5, a step for curing the silicone rubber is required, but there is a problem that the curing time is long. Further, when the silicone rubber is cured, siloxane gas may be generated, which may lead to contact failure of other parts such as switches.

Therefore, a main object of the present invention is to provide an ultrasonic sensor which has stable characteristics and is inexpensive.

[0010]

An ultrasonic sensor according to the present invention is provided with a piezoelectric vibrator, a housing for housing the piezoelectric vibrator, and an electrical connection to the piezoelectric vibrator, and the housing is externally connected to the piezoelectric vibrator. An ultrasonic sensor including an external terminal provided so as to extend, wherein one end portion of the external terminal extends into the housing and is directly fixed to the vicinity of the node of the piezoelectric vibrator. .

The external terminal is preferably made of a material having elasticity so that it is difficult to suppress the vibration of the piezoelectric vibrator.

Furthermore, it is preferable that the external terminals are formed of a thin metal plate from the viewpoint of easy handling.

Further, the piezoelectric vibrator is preferably supported by an external terminal inside the housing in order to reduce the number of parts and simplify the structure.

Furthermore, one end of the external terminal may be branched so as to support the vicinity of a plurality of nodes of the piezoelectric vibrator. Further, one end of the external terminal may be formed in an annular shape to support the vicinity of a plurality of nodes of the piezoelectric vibrator.

[0015]

By fixing one end of the external terminal directly to the vicinity of the node of the piezoelectric vibrator, the piezoelectric vibrator and the external terminal are directly electrically connected. Moreover, since one end of the external terminal is fixed near the node, it is difficult to suppress vibration of the piezoelectric vibrator. Further, the other end of the external terminal extends from the housing and is used as an input / output terminal. As described above, according to the present invention, the lead wire, which is required in the conventional ultrasonic sensor, becomes unnecessary, the number of parts is reduced, and the structure is simplified.

Further, by forming the external terminal from a material having elasticity, it becomes difficult to suppress the vibration of the piezoelectric vibrator. Therefore, for example, a cushioning material such as silicon rubber becomes unnecessary.

Further, by forming the external terminal from a thin metal plate, the external terminal is easy to handle and the assembly is easy.

Further, by supporting the piezoelectric vibrator inside the housing by the external terminals, a supporting member which is conventionally required only for supporting is unnecessary, the number of parts is reduced, and the structure is simplified. It

Further, by forming one end of the external terminal in a branched manner or forming it in an annular shape, it is possible to support the vicinity of a plurality of nodes of the piezoelectric vibrator. In these cases, it is possible to obtain an ultrasonic sensor having excellent impact resistance and good durability.

[0020]

According to the present invention, since the lead wire is not used, the step of winding the lead wire around the external terminal and soldering it becomes unnecessary, and the manufacturing process can be simplified. In addition, since no lead wire is used, no extra tension is applied to the piezoelectric vibrator. Therefore, the vibration of the piezoelectric vibrator is less likely to be suppressed, and the characteristics are stabilized. Further, it is not necessary to reinforce the connection between the external terminal and the piezoelectric vibrator with epoxy resin or the like.
Further, conventionally, the external terminal was press-fitted and fixed to the base member, but this is not necessary. Further, since silicone rubber is not used, adverse effects on other parts can be eliminated. Furthermore, since the number of parts such as lead wires can be reduced and handling can be facilitated, part cost and manufacturing cost can be reduced.

The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments with reference to the drawings.

[0022]

FIG. 1 is an illustrative view showing one embodiment of the present invention. FIG. 2 is a perspective view showing the external terminal of the embodiment shown in FIG. FIG. 3 is an exploded perspective view of the embodiment shown in FIG. The ultrasonic sensor 10 includes a piezoelectric vibrator 12 for electroacoustic conversion. The piezoelectric vibrator 12 includes a metal plate 12 having a substantially circular plane and made of a constant elastic metal such as elinvar.
a. The piezoelectric vibrator 12 is formed by adhering a substantially circular piezoelectric body 12b made of piezoelectric ceramic, for example. The piezoelectric vibrator 12 flexurally vibrates with a node line on the circumference of a predetermined distance from the center.

A substantially conical cone 14 for transmitting and receiving ultrasonic waves is fixed to the other surface of the metal plate 12a of the piezoelectric vibrator 12. The cone 14 is formed of a metal such as aluminum.

On the side of the piezoelectric vibrator 12 opposite to the cone 14, there is a predetermined space, and the base member 1 is substantially circular in plan view.
6 are arranged. The base member 16 is formed of an insulating material such as synthetic resin. Both sides of the base member 16 facing each other in the diametrical direction are formed in a linear shape so as to form passages 16a and 16b penetrating in the thickness direction between the base member 16 and a cover member 20 described later.

The ultrasonic sensor 10 has an external terminal 18a.
And 18b. The external terminals 18a and 18b are
A thin strip of thin metal plate with elasticity is shown in Fig. 2.
It is bent so as to be sandwiched from both sides in the thickness direction in the vicinity of the node of the piezoelectric vibrator 12 as shown in FIG.
That is, at the one ends of the external terminals 18a and 18b, sandwiching pieces 18a1 and 18b1 having a substantially planar I shape for sandwiching the piezoelectric vibrator 12 are formed. Holding piece 18a1
And 18b1 are arranged so as to extend substantially parallel to the main surface of the piezoelectric vibrator 12. Clamping piece 18a of external terminal 18a
One end of 1 is fixed to the other surface of the metal plate 12a of the piezoelectric vibrator 12 near the node by soldering or the like, and is electrically connected. In addition, the clamping piece 18 of the external terminal 18b
The one end portion of b1 cooperates with the sandwiching piece 18a1 to sandwich the piezoelectric vibrator 12, so that the piezoelectric body 1 of the piezoelectric vibrator 12 can be sandwiched.
It is fixed to the vicinity of the node on the main surface of 2b by soldering or the like and is electrically connected. At this time, the sandwiching piece 18a1
One end of each of 18b1 and 18b1 is formed by being bent into a substantially S shape so as to have a space with the piezoelectric vibrator 12 so as not to suppress the vibration of the piezoelectric vibrator 12. Then, the sandwiching piece 18 of the external terminals 18a and 18b
The other ends of a1 and 18b1 are formed so as to extend outward when viewed from the center of the piezoelectric vibrator 12.

At the other ends of the external terminals 18a and 18b,
Support pieces 18a2 and 18b2 for supporting the sandwiching pieces 18a1 and 18b1 are sandwiched by the sandwiching pieces 18a1 and 18b.
It is formed integrally with the other end of b1. The support pieces 18a2 and 18b2 have a predetermined space between the main surface and the end surface of the piezoelectric vibrator 12 in order to prevent the vibration of the piezoelectric vibrator 12 from being suppressed.
4 is formed so as to extend in the opposite direction. The support pieces 18a2 and 18b2 are inserted into the passages 16a and 16b, respectively, and then bent into a substantially L shape to be fixed to the surface of the base member 16 opposite to the piezoelectric vibrator 12. After that, the support pieces 18a2 and 18b2 are
Further, the base member 16 is bent into a substantially L-shape and is formed so as to extend to the side opposite to the piezoelectric vibrator 12 of the base member 16. Support pieces 18a2 and 18 for the external terminals 18a and 18b
b2 is used as an input / output terminal of the ultrasonic sensor 10.

The ultrasonic sensor 10 has a cross section of approximately U.
It includes a V-shaped cover member 20. The cover member 20 forms a housing of the ultrasonic sensor 10 together with the base member 16. A through hole 20 for transmitting and receiving ultrasonic waves is provided in a portion of the cover member 20 facing the cone 14.
a is formed. A screen (not shown) for protecting the inside of the housing is provided in the through hole 20a. The cover member 20 includes the piezoelectric vibrator 12 and the cone 1.
4 is fixed to the end surface of the base member 16 so as to cover the base member 4. Therefore, the above-mentioned external terminals 18a and 18b
Has one end directly fixed to the vicinity of the node of the piezoelectric vibrator 12 and the other end provided so as to extend from the inside of the housing to the outside.

In the ultrasonic sensor 10 of this embodiment, as described above, the external terminals 18a and 18b sandwich and support the vicinity of the node of the piezoelectric vibrator 12. Moreover, the external terminals 18a and 18b are formed of a thin metal plate having elasticity. Therefore, the piezoelectric vibrator 1
The vibration of 2 is difficult to suppress. Further, unnecessary vibration can be absorbed without using a cushioning material such as silicon rubber as in the conventional case. Further, the external terminals 18a and 1
Since 8b enables support and electrical connection, the number of parts can be reduced. Further, since the external terminals 18a and 18b and the piezoelectric vibrator 12 are directly electrically connected to each other, the conventional lead wire is unnecessary. Further, since the external terminals 18a and 18b are formed of thin metal plates, they are easier to handle and easier to assemble than lead wires.

Further, according to the embodiment shown in FIG. 1, since the lead wire is not used, the step of winding the lead wire around the external terminal and soldering it becomes unnecessary, and the manufacturing process can be simplified. Further, since no lead wire is used, no extra tension is applied to the piezoelectric vibrator 12. Therefore, the vibration of the piezoelectric vibrator 12 is less likely to be suppressed, and the characteristics are stabilized. Also,
It is not necessary to reinforce the connection between the external terminals 18a and 18b and the piezoelectric vibrator 12 with epoxy resin or the like. Further, conventionally, the external terminals 18a and 18b were press-fitted and fixed to the base member 16, but this is not necessary.
Further, since silicone rubber is not used, adverse effects on other parts can be eliminated. Further, since the number of parts such as lead wires can be reduced and handling can be facilitated, the manufacturing process can be simplified, and the parts cost and the manufacturing cost can be reduced.

FIG. 4 is a perspective view showing a modification of the external terminals 18a and 18b. The external terminals 18a and 18b shown in FIG. 4 are different from those shown in FIG.
Holding pieces 18a1 and 18b1 at one end of a and 18b
Are each branched into a substantially U-shaped plane. One end of each of the sandwiching pieces 18a1 and 18b1 is formed by being bent in a substantially S shape so as to have a space with the piezoelectric vibrator 12 so as not to suppress the vibration of the piezoelectric vibrator 12. In addition, support pieces 18a2 and 18b2 are integrally formed at the central portions on the other end sides of the sandwiching pieces 18a1 and 18b1.

FIG. 5 is a perspective view showing a state of support by the external terminals 18a and 18b shown in FIG. In the case shown in FIG. 5, the external terminals 18a and 18b shown in FIG.
The piezoelectric vibrator 12 is connected to four locations near the node. As described above, according to the external terminals 18a and 18b shown in FIG. 4, the piezoelectric vibrator 12 can be reliably sandwiched, and the ultrasonic sensor 10 that is resistant to external impact and has high durability can be obtained.

FIG. 6 is a perspective view showing another modification of the external terminals 18a and 18b. External terminal 18 shown in FIG.
a and 18b are different from those shown in FIG. 2 in that they sandwich the holding pieces 18a1 and 18a at one end of the external terminals 18a and 18b.
Each b1 is formed in a ring shape. In this case, the sandwiching pieces 18a1 and 18b1 are formed in an annular shape having a diameter larger than that of the piezoelectric vibrator 12 having a substantially circular plane in order to protect the piezoelectric vibrator 12. Holding pieces 18a1 and 18b
1 is arranged in parallel with both main surfaces of the piezoelectric vibrator 12 with a space. And, from the sandwiching pieces 18a1 and 18b1, four sandwiching pieces 18a3 and 18b3 each having a substantially planar I-shape are arranged at equal intervals in the circumferential direction,
It is formed so as to project toward the center of the piezoelectric vibrator 12. One end of each of the eight sandwiching pieces 18a3 and 18b3 is formed by being bent in a substantially S shape so as to have a space with the piezoelectric vibrator 12 so as not to suppress the vibration of the piezoelectric vibrator 12. . Also, the sandwiching piece 1
Support pieces 18a2 and 18b2 are integrally formed on the outer edges of 8a1 and 18b1.

FIG. 7 is a perspective view showing a supporting state by the external terminals 18a and 18b shown in FIG. In the case shown in FIG. 7, the external terminals 18a and 18b shown in FIG.
The piezoelectric vibrator 12 is connected to eight locations near the node. Moreover, in this case, the holding pieces 18a3 and 18b3
Are arranged and provided so as to face each other in the thickness direction of the piezoelectric vibrator 12. Therefore, the external terminal 18 shown in FIG.
According to a and 18b, the piezoelectric vibrator 12 can be more reliably sandwiched, and the ultrasonic sensor 10 that is strong against external impact and has high durability can be obtained.

FIG. 8 is a perspective view showing a modification of the supporting condition shown in FIG. As shown in FIG. 8, one end may have a planar annular external terminal 18a and one end may have a planar substantially I-shaped external terminal 18b in combination. Similarly, although not shown, one end of the external terminal 18a having a substantially I shape and one end of the external terminal 18b having an annular shape may be used in combination.

Further, FIG. 9 is a perspective view showing a modification of the external terminal shown in FIG. External terminal 18a shown in FIG.
6 includes a holding ring 18a3 for annularly supporting and electrically connecting the node line of the piezoelectric vibrator 12 as compared with that shown in FIG. The holding ring 18a3 is an annular holding piece 1
8a1 is disposed inside and is formed in an annular shape having a diameter smaller than that of the sandwiching piece 18a1. Holding ring 18a3 and holding piece 18
For example, four connecting pieces 18a4 are connected to a1. At this time, the sandwiching ring 18a3 is replaced by the sandwiching piece 18a1.
Is arranged so as to protrude from the piezoelectric vibrator 12 toward the piezoelectric vibrator 12. The holding ring 18a3 is fixed near the node line of the piezoelectric vibrator 12. External terminal 18a shown in FIG.
The piezoelectric vibrator can be supported by using the same as that shown in FIGS. 7 and 8. Further, although not shown, the external terminal 18b may be similarly formed. 4 to 9
According to the modification shown in FIG. 4, the same effect as that of the embodiment shown in FIG. 1 can be obtained.

FIG. 10 is an illustrative view showing another embodiment of the present invention, and FIG. 11 is a perspective view of the main part thereof. In this modification, the piezoelectric vibrator 12 is supported similarly to the conventional example. Then, the external terminals 18a and 18b shown in FIG.
Is fixed and electrically connected to the vicinity of the node of the piezoelectric vibrator 12 by, for example, soldering. In this case, as shown in FIG. 11, the base member 16 is cut out to form the passages 16a and 16b. The external terminals 18a and 18b are connected to the passages 16a and 16b.
The base member 16 is arranged so as to extend to both sides in the thickness direction. In the case of the modified example shown in FIG. 10, the tension as when using the conventional lead wire is not applied to the fixed portion between the piezoelectric vibrator 12 and the external terminals 18a and 18b, and therefore it is necessary to reinforce with an epoxy resin or the like. Absent.

In the above embodiment, the external terminal 18a is used.
And 18b are fixedly provided on the surface of the base member 12 on the side opposite to the piezoelectric vibrator 12, but not limited to this, for example,
It may be provided so as to be sandwiched between the base member 12 and the cover member 20.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing an external terminal of the embodiment shown in FIG.

FIG. 3 is an exploded perspective view of the embodiment shown in FIG.

FIG. 4 is a perspective view showing a modified example of the external terminal shown in FIG.

5 is a perspective view showing a supporting state by the external terminal shown in FIG. 4. FIG.

FIG. 6 is a perspective view showing another modification of the external terminal shown in FIG.

FIG. 7 is a perspective view showing a supporting state by the external terminal shown in FIG.

FIG. 8 is a perspective view showing a modification of the supporting condition shown in FIG.

9 is a perspective view showing a modified example of the external terminal shown in FIG.

FIG. 10 is an illustrative view showing another embodiment of the present invention;

11 is a perspective view of a main part of the modified example shown in FIG.

FIG. 12 is a cross sectional view showing an example of a conventional ultrasonic sensor which is a background of the present invention.

13 is a perspective view showing a main part of the ultrasonic sensor shown in FIG.

[Explanation of symbols]

 10 Ultrasonic Sensor 12 Piezoelectric Vibrator 12a Metal Plate 12b Piezoelectric Body 14 Cone 16 Base Member 16a, 16b Passage 18a, 18b External Terminal 20 Cover Member 20a Through Hole 18a1, 18b1 Clamping Piece 18a2, 18b2 Support Piece 20 Cover Member

Claims (6)

[Claims] 1. A piezoelectric vibrator, a housing for accommodating the piezoelectric vibrator, and an external terminal electrically connected to the piezoelectric vibrator and provided so as to extend to the outside from the housing. It is an ultrasonic sensor, Comprising: One end part of the said external terminal extends inside the said housing | casing, and is fixed directly to the node vicinity of the said piezoelectric vibrator. 2. The ultrasonic sensor according to claim 1, wherein the external terminal is made of a material having elasticity. 3. The ultrasonic sensor according to claim 1, wherein the external terminal is formed of a thin metal plate. 4. The ultrasonic sensor according to claim 1, wherein the piezoelectric vibrator is supported by the external terminal inside the housing. 5. The ultrasonic sensor according to claim 1, wherein one end of the external terminal is formed to be branched so as to support the vicinity of a plurality of nodes of the piezoelectric vibrator. . 6. The ultrasonic sensor according to claim 1, wherein one end of the external terminal is formed in a ring shape to support the vicinity of a plurality of nodes of the piezoelectric vibrator.