JP3721786B2 - Ultrasonic sensor and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic sensor, and more particularly to an ultrasonic sensor used as an automobile back sonar and corner sonar.
[0002]
[Prior art]
In recent years, in the field of ultrasonic sensors, there is an increasing demand for short-distance type ultrasonic sensors for detecting an object to be detected that is close to the wave transmitting / receiving surface of the sensor. In the ultrasonic sensor for such use, the most serious problem as a cause of the measurement error at the time of distance measurement is interference between the reverberation wave of the transmission signal and the reception signal. When measuring the proximity distance, since the reverberation characteristics influence the measurement reliability of the sensor, improvement of the reverberation characteristics is a big issue.
[0003]
In response to this problem, an ultrasonic sensor 51 having a structure shown in FIGS. 8A and 8B has been proposed. In the ultrasonic sensor 51 shown in FIG. 8A, a plate-like piezoelectric vibrator 53 having electrodes formed on both main surfaces thereof is disposed on the inner bottom surface of a bottomed cylindrical case 52 made of metal. . A locking step 62 is provided on the inner side surface of the bottomed cylindrical case 52, and a cushioning material 54 made of silicon rubber is locked by the locking step 62 and is press-fitted inside the bottomed cylindrical case 52. Has been. A substrate 56 having external terminals 55a and 55b is disposed on the cushioning material 54. The substrate 56 is fixed to the buffer material 54 with an adhesive, or is fixed by folding and crimping the opening of the bottomed cylindrical case 52 inside the case. On both main surfaces of the substrate 56, wiring patterns 57a and 57b that are electrically connected to the external terminals 55a and 55b are formed, respectively. The wiring pattern 57 a is electrically connected to the electrode on the upper surface of the piezoelectric vibrator 53 via the wire 58. The wiring pattern 57b is electrically connected to an electrode on the lower surface of the piezoelectric vibrator 53 through a metal bottomed cylindrical case 52 (the wiring pattern 57b and the bottomed cylindrical case 52 are connected by solder 59). ing). The ultrasonic sensor 61 in FIG. 8B is obtained by replacing the silicone rubber cushioning material 54 in FIG. 8A with a cotton-like cushioning material 64, and the other configuration is the ultrasonic wave in FIG. 8A. There is no difference from the sensor 51.
[0004]
Next, the operation of the ultrasonic sensor 51 will be described. First, a drive voltage is applied to the external terminals 55a and 55b of the ultrasonic sensor 51 to vibrate the piezoelectric vibrator 53. In conjunction with the vibration of the piezoelectric vibrator 53, the vibration surface 60 of the bottomed cylindrical case 52 vibrates and emits ultrasonic waves in the direction of the arrow shown in FIG. After a predetermined time has elapsed, the ultrasonic wave reflected from the object to be detected reaches the piezoelectric vibrator 53 via the vibration surface 60 and is converted into a reflected signal, and is output from the external terminals 55a and 55b. Here, the time from the application time point of the drive voltage to the output time point of the reflected signal is detected, and the distance from the detected object is measured from the detection result.
[0005]
In the above operation process, not only the vibration surface 60 but also the entire bottomed cylindrical case 52 vibrates in conjunction with the vibration of the piezoelectric vibrator 53, and this vibration causes a reverberant wave. Further, the vibration of the piezoelectric vibrator 53 generates ultrasonic waves not only in the arrow direction shown in FIG. 8A but also in the inner direction of the bottomed cylindrical case 52. Therefore, the ultrasonic waves inside the case 52 also reverberate. Become a wave.
[0006]
With respect to these reverberation waves, the reverberation waves generated from the vibration of the bottomed cylindrical case 52 are suppressed by the restoring force of the silicon rubber press-fitted into the case 52 as shown in FIG. Further, the ultrasonic waves generated in the inner direction of the case 52 are absorbed and suppressed by a cotton-like cushioning material 64 packed in the case 52 as shown in FIG. By these methods, the reverberation characteristics of the ultrasonic sensor can be improved.
[0007]
As another conventional example, a configuration for suppressing a reverberation wave and improving a reverberation characteristic by using a foamable resin having a low Q value is disclosed in, for example, Japanese Utility Model Laid-Open No. 5-63196 and Japanese Patent Laid-Open No. 7-154898. ing. In other words, a technique for improving reverberation characteristics by forming a bottomed cylindrical case from a foamable resin and a technique for improving reverberation characteristics by joining a piezoelectric vibrator on a plate-like foamable resin are disclosed. Yes.
[0008]
[Problems to be solved by the invention]
However, when the reverberation characteristics are to be improved using the configuration shown in FIG. 8A, unnecessary vibration of the case 52 can be suppressed by the restoring force of the silicon rubber, but unnecessary ultrasonic waves generated inside the case 52 are rubber. Since it propagates freely, it cannot absorb sound sufficiently, and there is a limit to improving the reverberation characteristics. In general, silicon rubber has a very strong restoring force and is therefore suitable as a shock absorbing material for damping purposes. However, even the vibration surface 60 that needs to be vibrated is also damped, and ultrasonic waves are transmitted. In addition, there is a problem that a failure occurs in reception and the sensitivity of the ultrasonic sensor 51 deteriorates.
[0009]
Further, when reverberation characteristics are to be improved by using the configuration shown in FIG. 8B, unnecessary ultrasonic waves generated inside the case 52 can be absorbed, but the cushioning material is cottony so that the adhesion to the case 52 is improved. The unnecessary vibration of the case 52 cannot be sufficiently suppressed, and the improvement of the reverberation characteristic has a limit.
[0010]
Furthermore, when the bottomed cylindrical case is made of a foamable resin, it takes time to form the foamable resin into a cylindrical shape, and there are a large number of depletions (foam holes) inside the foamable resin. Therefore, problems such as lack of strength and durability as a case are cited.
[0011]
Furthermore, when the plate-like foaming resin is bonded to the piezoelectric vibrator, the foaming resin with high damping is directly attached to the piezoelectric vibrator, so the sensitivity characteristics deteriorate during spreading vibration. Is a problem that cannot be avoided.
[0012]
Therefore, an object of the present invention is to solve the above technical problems, and by effectively suppressing both vibration of the bottomed cylindrical case and ultrasonic waves generated inside the case. An object of the present invention is to provide an ultrasonic sensor capable of greatly improving reverberation characteristics.
[0017]
[Means for Solving the Problems]
In order to solve the above problems, an ultrasonic sensor according to claim 1 of the present invention includes: a bottomed cylindrical case, and the piezoelectric vibrator is disposed on an inner bottom portion of the bottomed cylindrical case, the piezoelectric vibrator An ultrasonic sensor having an input / output terminal electrically connected to the bottomed cylindrical case and a buffer material for suppressing a reverberation wave, which is solidified in advance to the buffer material A resin plug made of foamable resin is used, and the resin plug is inserted and fixed inside the bottomed cylindrical case with a gap from the piezoelectric vibrator.
[0018]
Thus, when using foamable resin as a buffer material, it is good also as a structure which uses foamable resin solidified previously as a stopper (resin stopper).
[0019]
That is, as a method for manufacturing an ultrasonic sensor, a method of filling a liquid foamable resin inside a bottomed cylindrical case and solidifying it by a method such as thermosetting or time-curing after filling is considered as one method. Is done.
However, if the liquid resin is filled into the case, the resin is filled without a gap up to the bottom (vibration surface) of the case, so there is a concern that sensitivity characteristics may be deteriorated due to vibration inhibition of the vibration surface.
[0020]
In this regard, this concern can be eliminated by taking a technique of solidifying the foamable resin outside the case in advance and inserting and fixing the solidified resin into the case as a plug (resin plug). That is, when the resin plug is inserted and fixed inside the case, the resin plug is fixed at a position where it does not contact the vibration surface and the piezoelectric vibrator, thereby preventing vibration inhibition of the vibration surface. In addition, after inserting and fixing the resin stopper, a resin having a strong restoring force such as silicon rubber may be further stacked on the resin stopper.
[0021]
Further, it is desirable that at least one main surface of the resin plug to be used is a skin layer having no foaming holes due to foaming of the resin. This is because the foam plug has a large number of foam holes due to its structure. For example, when a different resin is filled in the upper part of the resin plug, the liquid resin travels through the continuous foam holes in the resin plug. This is because it may flow out to the back side of the resin stopper. This outflow can be prevented if at least one main surface of the resin plug is brought into a state in which no foam holes are present (a state in which a skin layer is formed). The skin layer mentioned here is most preferably in a state where the foamed holes are not completely present, but the foamed holes may be present to such an extent that the liquid resin can be prevented from flowing out.
[0022]
In addition, as a bottomed cylindrical case used for the ultrasonic sensor of the present invention, the cylindrical portion and the vibration surface (bottom surface) are formed of a metal material, or a cylindrical portion made of plastic and a metallic material. Any of those formed in combination with the vibration surface made in (1) may be used. In the former case, a light and high elastic modulus aluminum or the like is suitable as a material for the bottomed cylindrical case. In the latter case, engineering plastic materials with excellent heat resistance and durability, specifically, polyphenylene sulfide, polyether ether ketone, polyether sulfone, etc. are suitable as the material of the cylindrical part, and are light and elastic. A material such as high aluminum is suitable as a material for the vibration surface.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0024]
[First embodiment, FIGS. 1 to 3]
The structure of the ultrasonic sensor 1 according to the first embodiment of the present invention will be described below with reference to FIG.
[0025]
In the ultrasonic sensor 1 shown in FIG. 1, plate-shaped piezoelectric vibrators 3 having electrodes formed on both main surfaces thereof are disposed on the inner bottom surface of a bottomed cylindrical case 2 made of metal such as aluminum. Yes. Almost the entire inside of the bottomed cylindrical case 2 is filled with a foaming resin such as foamed silicon as the buffer material 4. A substrate 6 having external terminals 5a and 5b is disposed on the cushioning material 4. The substrate 6 is fixed to the cushioning material 4 with an adhesive, or is fixed by bending and crimping the opening of the bottomed cylindrical case 2 inside the case. On both main surfaces of the substrate 6, wiring patterns 7a and 7b that are electrically connected to the external terminals 5a and 5b are formed, respectively. The wiring pattern 7 a is electrically connected to the electrode on the upper surface of the piezoelectric vibrator 3 through the wire 8. The wiring pattern 7b is electrically connected to an electrode on the lower surface of the piezoelectric vibrator 3 through a metal bottomed cylindrical case 2 (the wiring pattern 7b and the bottomed cylindrical case 2 are connected by solder 9). ing). In this embodiment, piezoelectric vibrators having electrodes formed on both main surfaces are used. However, the present invention is not limited to this. That is, for example, an electrode is not necessarily formed on the main surface of the piezoelectric vibrator on the side in contact with the vibration surface 10. This is because the bottomed cylindrical case 2 having conductivity can function as an electrode.
[0026]
The ultrasonic sensor 1 having the above configuration is assembled as follows.
[0027]
First, the piezoelectric vibrator 3 is fixed to the inner bottom surface of the bottomed cylindrical case 2 with solder, a conductive adhesive or the like. Next, the electrode on the upper surface side of the piezoelectric vibrator 3 and the wiring pattern 7 a on the substrate 6 are electrically connected using a wire 8. Then, the case 2 is filled with a liquid foamable resin, and the substrate 6 is placed thereon. Thereafter, the foamable resin is solidified using a predetermined method, and after the resin is solidified, the wiring pattern 7 b and the case 2 are connected by the solder 9. In this way, the ultrasonic sensor 1 is assembled.
[0028]
Next, the operation of the ultrasonic sensor 1 will be described. First, a driving voltage is applied to the external terminals 5 a and 5 b of the ultrasonic sensor 1 to vibrate the piezoelectric vibrator 3. In conjunction with the vibration of the piezoelectric vibrator 3, the vibration surface 10 of the bottomed cylindrical case 2 vibrates and emits ultrasonic waves in the direction of the arrow shown in FIG. After a lapse of a predetermined time, the ultrasonic wave reflected from the object to be detected reaches the piezoelectric vibrator 3 through the vibration surface 10, is converted into a reflected signal, and is output from the external terminals 5a and 5b. Here, the time from the application time point of the drive voltage to the output time point of the reflected signal is detected, and the distance from the detected object is measured from the detection result.
[0029]
The reverberant wave generated in the above operation process is suppressed as follows in the ultrasonic sensor 1 of the present embodiment.
[0030]
First, since the volume of the foamable resin filled in the bottomed cylindrical case 2 is increased by foaming, the adhesiveness to the case 2 is enhanced, and the force (restoration) that pushes the case 2 from the inside to the outside Power) will work. This force can suppress the vibration of the bottomed cylindrical case 2 as a whole. Further, since the ultrasonic waves are scattered and absorbed by a large number of depletions (foam holes) existing inside the foamable resin, the ultrasonic waves generated inside the case 2 can be absorbed and suppressed. As a result, it is possible to efficiently suppress both the vibration of the case 2 itself and the ultrasonic wave trapped inside the case, and the reverberation characteristics can be greatly improved.
[0031]
Here, the preferable conditions calculated | required by the foamable resin used for this invention are examined. That is, in general, the reverberation characteristics of the ultrasonic sensor tend to be improved by using a resin having a high density for the buffer material 4, while the sensitivity characteristics of the ultrasonic sensor tend to deteriorate. Therefore, the resin density range in which preferable characteristics are obtained in both reverberation characteristics and sensitivity characteristics is examined.
[0032]
First, a graph showing the relationship between resin density and reverberation characteristics is shown in FIG. As is apparent from this graph, when the density of the foamable resin used is less than 0.01 g / cm ³ , the reverberation time is abruptly increased and desired reverberation characteristics cannot be obtained. Next, the graph which shows the relationship between a resin density and a sensitivity characteristic is shown in FIG. As is apparent from this graph, when the density of the foamable resin to be used exceeds 0.9 g / cm ³ , the sensitivity voltage is drastically lowered, and desired sensitivity characteristics cannot be obtained.
[0033]
From the above examination, an ultrasonic sensor that can obtain favorable characteristics in both reverberation characteristics and sensitivity characteristics by setting the resin density of the foamable resin to be used in the range of 0.01 to 0.9 g / cm ³ is obtained. I understand that
[0034]
In the ultrasonic sensor of this embodiment, unlike the conventional example, the bottom portion (vibration surface 10) of the case 2 where the piezoelectric vibrator 3 is arranged is filled with a foaming resin as a buffer material without a gap. Although there is concern about deterioration of sensitivity characteristics, it has been confirmed that sensitivity characteristics exceeding those of conventional ultrasonic sensors can be obtained by using a foamable resin that satisfies the above-described conditions.
[0035]
[Second Embodiment, FIG. 4]
The structure of the ultrasonic sensor according to the second embodiment of the present invention will be described below with reference to FIG.
[0036]
In the ultrasonic sensor 21 shown in FIG. 4, the bottomed cylindrical case 22 is formed by combining a separate cylindrical portion 22a and a vibrating surface 22b. An engineering plastic material excellent in heat resistance and durability, specifically, polyphenylene sulfide, polyether ether ketone, polyether sulfone, or the like is used for the cylindrical portion 22a. A material such as aluminum that is light and has a high elastic modulus is used for the vibration surface 22b. A conductive member 28 such as a wire is embedded in the cylindrical portion 22a, one of which is connected to an electrode formed on one main surface of the piezoelectric vibrator 23 with solder or a conductive adhesive, The other one has one end connected to a metallic vibration surface 22b. Each other end is pulled out of the cylindrical portion 22a. The conductive member 28 makes electrical connection between the electrodes formed on both main surfaces of the piezoelectric vibrator 23 and an external circuit (not shown). Further, almost the entire interior of the bottomed cylindrical case 22 is filled with a foaming resin such as foamed silicon as the buffer material 24.
[0037]
The ultrasonic sensor 21 having the above configuration is assembled as follows.
[0038]
First, the piezoelectric vibrator 23 is fixed to the inner bottom surface (vibration surface) of the bottomed cylindrical case 22 with solder, a conductive adhesive, or the like. Next, one end of the conductive member 28 is connected to one main surface and the vibration surface of the piezoelectric vibrator with solder, a conductive adhesive, or the like. Then, the inside of the case 22 is filled with a liquid foamable resin, and the resin is cured using a predetermined method. In this way, the ultrasonic sensor 21 is assembled.
[0039]
Thus, by embedding the conductive member 28 in the cylindrical portion 22a, parts such as a substrate and external terminals that have been conventionally required can be made unnecessary, and further, the method of making an ultrasonic sensor can be simplified. Is possible.
[0040]
The other points are not different from the ultrasonic sensor 1 of the first embodiment, and the description thereof is omitted.
[0041]
[Third embodiment, FIG. 5]
As shown in FIG. 5, in the ultrasonic sensor 31 of the third embodiment of the present invention, the buffer material of the ultrasonic sensor 21 of the second embodiment is composed of a plurality of resin layers.
[0042]
As the structure of this layer, the first resin layer 34a disposed immediately above the vibration surface 22b is made of the foamable resin having the predetermined density. For the second resin layer, a resin having a higher density than that of the first layer resin, such as silicon rubber, is used.
[0043]
By providing the buffer material 34 with such a laminated structure, the ultrasonic wave transmission / reception on the vibration surface 22b achieves the sensitivity characteristics equivalent to those of the second embodiment, while the portion away from the vibration surface 22b, that is, the sensitivity. By using high-density silicon rubber as a cushioning material in a portion that does not easily affect the characteristics, unnecessary vibration of the cylindrical portion 22a can be suppressed more strongly than the foamable resin of the first layer. Further improvement can be achieved.
[0044]
The other points are not different from the ultrasonic sensor 21 of the second embodiment, and the description thereof is omitted.
[0045]
Similarly, in the ultrasonic sensor 1 of the first embodiment, the buffer material can have such a laminated structure.
[0046]
[Fourth embodiment, FIGS. 6 to 7]
The structure of the ultrasonic sensor according to the fourth embodiment of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected about the component same as the ultrasonic sensor shown to the above-mentioned each Example.
[0047]
FIG. 6A is a cross-sectional view showing the ultrasonic sensor 41. In FIG. 6A, a disc-shaped resin plug 42 made of a foamed resin that has been solidified in advance is inserted into the bottomed cylindrical case 2 and is fixed to the piezoelectric vibrator 3 with a gap. ing. A resin 43 such as silicon rubber having a density higher than that of the resin plug 42 is placed on top of the resin plug 42. A buffer material 44 is constituted by the resin plug 42 and the resin 43, and the buffer material 44 efficiently suppresses the vibration of the case 2 itself and absorbs the ultrasonic waves trapped inside the case 2. A substrate 6 having external terminals 5a and 5b is disposed on the resin 43, and is fixed to the buffer material 44 using an adhesive or the like. Other configurations are the same as those of the ultrasonic sensor 1 according to the first embodiment, and a description thereof will be omitted.
[0048]
In addition, regarding the method of manufacturing the ultrasonic sensor 41, the step of filling the case 2 with the liquid foamable resin is replaced with the step of inserting and fixing the resin stopper 42 and filling the upper portion thereof with silicon rubber. There are no essential changes in the manufacturing method of the ultrasonic sensor 1 of the first embodiment.
[0049]
FIG. 6B is a cross-sectional view showing still another ultrasonic sensor 45 of the present embodiment. An ultrasonic sensor 45 shown in FIG. 6B is formed by combining a bottomed cylindrical case 22 with a separate cylindrical portion 22a and a vibrating surface 22b, like the ultrasonic sensor 21 of the second embodiment. Has been. In FIG. 6B, a disc-shaped resin plug 46 made of a foamed resin that has been solidified in advance is inserted into the bottomed cylindrical case 22, and is fixed at a distance from the piezoelectric vibrator 3. ing. On top of the resin plug 46, a resin 47 having a higher density than the resin plug 46, such as silicon rubber, is disposed. A buffer material 48 is constituted by the resin plug 46 and the resin 47, and the buffer material 48 efficiently suppresses the vibration of the case 22 itself and absorbs the ultrasonic waves trapped inside the case 22. Other configurations are the same as those of the ultrasonic sensor 21 of the second embodiment, and the description thereof is omitted.
[0050]
In addition, regarding the method of manufacturing the ultrasonic sensor 45, the step of filling the liquid foamable resin in the case 22 is replaced with the step of inserting and fixing the resin plug 46 and filling the upper portion thereof with silicon rubber. There are no changes in the manufacturing method of the ultrasonic sensor 21 of the second embodiment.
[0051]
Thus, this embodiment is characterized in that the resin stopper 42 (46) made of a foamed resin that has been solidified in advance is used. By adopting a method of inserting and fixing the solidified resin plug into the case, it is possible to fix the resin plug at a position spaced from the vibration surface or the piezoelectric vibrator. Therefore, it is possible to solve the problem that may occur when filling the liquid foamable resin from the bottom of the case (vibration surface) without any gap, specifically, the problem of deterioration of sensitivity characteristics due to vibration inhibition of the vibration surface. it can.
[0052]
Here, the resin plug 42 inserted into the case will be described. FIG. 7 is a perspective view showing a resin plug used in this embodiment. In FIG. 7A, the resin plug 42 is a disc-shaped foaming resin having a diameter substantially the same as the inner diameter of the bottomed cylindrical case 2. The resin stopper 42 is already solidified when it is inserted into the case 2. The resin plug 42 has a large number of foam holes 49. One main surface of the resin plug 42 is a skin layer 50 having no foamed holes 49. The skin layer 50 may be formed by sticking a thin film on the surface of the foamable resin, or a layer formed naturally in the foaming process may be used.
[0053]
By using the resin plug having the skin layer as described above, even when the resin plug 42 is inserted into the case 2, even if the liquid plug 42 is filled with liquid silicone rubber or the like on the top of the resin plug 42, Since there is a skin layer on the surface that does not have foam holes that can become liquid passages, there is no risk of liquid leaking to the back side of the resin plug (liquid silicone rubber is used as a resin plug). If the sensor leaks out and adheres to the vibration surface or the piezoelectric vibrator, the sensitivity characteristics of the sensor may deteriorate.
[0054]
In the present embodiment, the resin stopper having the skin layer 50 is used. However, even if the resin stopper does not have the skin layer as shown in FIG. Needless to say, the internal ultrasonic wave can be effectively absorbed.
[0055]
【effect】
As is clear from the above description, the ultrasonic sensor of the present invention has the following excellent effects.
[0056]
That is, by filling the bottomed cylindrical case with foaming resin and using this foaming resin as a buffer to suppress reverberation waves, both vibration of the case itself and ultrasonic waves inside the case are efficiently suppressed. As a result, the reverberation characteristics of the ultrasonic sensor can be greatly improved. At that time, since the foaming resin does not have a restoring force as strong as that of the conventional rubber, the vibration surface is not pressed more than necessary, and the adverse effect on the sensitivity characteristics of the ultrasonic sensor can be suppressed to a low level.
[0057]
Further, by making the buffer material a laminated structure of a foamable resin and another resin, it becomes possible to more efficiently suppress the vibration of the case without reducing the sensitivity of the ultrasonic sensor.
[0058]
In addition, it is possible to fix the resin plug at a position spaced from the vibration surface or piezoelectric vibrator by inserting and fixing a resin plug made of foamed resin that has been solidified in advance into the case. become. Therefore, the problem that may occur when the liquid foamable resin is filled from the case bottom (vibration surface), specifically, the problem of deterioration of sensitivity characteristics due to vibration inhibition of the vibration surface can be solved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an ultrasonic sensor according to a first embodiment of the present invention.
FIG. 2 is a graph showing the relationship between the resin density and reverberation characteristics of an expandable resin used in the ultrasonic sensor of the present invention.
FIG. 3 is a graph showing the relationship between the resin density and sensitivity characteristics of a foamable resin used in the ultrasonic sensor of the present invention.
FIG. 4 is a cross-sectional view showing an ultrasonic sensor according to a second embodiment.
FIG. 5 is a cross-sectional view showing an ultrasonic sensor according to a third embodiment.
6A and 6B are cross-sectional views showing an ultrasonic sensor according to a fourth embodiment.
FIGS. 7A and 7B are perspective views showing resin plugs used in the ultrasonic sensor of the fourth embodiment. FIGS.
8A and 8B are cross-sectional views showing a conventional ultrasonic sensor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Ultrasonic sensor 2 ... Bottomed cylindrical case 3 ... Piezoelectric vibrator 4 ... Buffer material 5a, 5b ... External terminal 6 ... Substrate 7a, 7b ... Wiring pattern 8 ... Wire (conductive member)
9 ・ ・ ・ Solder 10 ・ ・ ・ Vibration surface

Claims (4)

A bottomed cylindrical case, a piezoelectric vibrator disposed on the inner bottom portion of the bottomed cylindrical case, an input / output terminal electrically connected to the piezoelectric vibrator and drawn out of the bottomed cylindrical case, and a reverberant wave An ultrasonic sensor comprising a buffer material for suppressing,
An ultrasonic sensor characterized in that a resin plug made of a foamed resin that has been solidified in advance is used as the cushioning material, and the resin plug is inserted and fixed inside the bottomed cylindrical case with a gap from the piezoelectric vibrator. . The ultrasonic sensor according to claim 1 , wherein a resin having a density different from that of the resin plug is disposed on the resin plug in an overlapping manner. The resin plugs are at least one main surface is, the ultrasonic sensor according to claim 1 or claim 2, characterized in that has a skin layer having no foamed pores due to foaming of the resin. The bottomed cylindrical case, the ultrasonic sensor of claim 1 to claim 3, wherein the formed by combining a cylindrical portion made of a plastic material, a vibrating surface of a metal material.

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