JPH05207594A - Ultrasonic wave sensor - Google Patents

Abstract

PURPOSE:To prevent a reverberation characteristic from being unstable even when an ultrasonic wave vibrator whose side face is pressed and supported by a support member so as to prevent vibration is accommodated into a forming-made housing. CONSTITUTION:After an ultrasonic wave vibrator is surrounded from its side face by a support member 2 having an opening used to send/receive an ultrasonic wave, the support member is contained in a housing made of a forming. Then a projection strip 2a is provided to the inside of the support member 2 so as to pressure the support and to prevent the vibration of a loop of a side face of the ultrasonic wave vibrator on the production of an ultrasonic wave.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic sensor which detects the reflected waves of ultrasonic waves emitted intermittently and determines the presence of obstacles.

[0002]

2. Description of the Related Art When an ultrasonic pulse is intermittently transmitted from an ultrasonic sensor to an obstacle, the ultrasonic wave is adapted to detect the reflected wave returned from the obstacle and determine the presence or absence of the obstacle. Although a sensor is known, this type of ultrasonic sensor has a structure as shown in FIGS. That is, in such an ultrasonic sensor, the ultrasonic transducer 1 is
A holding member 5 having an opening 5a at its tip surrounds the entire side surface, and the holding member 5 is further housed in a housing 4 made of a molded product, and a drive signal is applied to the ultrasonic transducer 1. At this time, the built-in piezoelectric element 10 is vibrated, and the ultrasonic wave generated at that time is emitted from the tip opening 5a of the holding member 5. As shown in FIG. 3, the ultrasonic transducer 1 has the piezoelectric element 10 attached to the inner upper surface of the cylindrical case 11, the piezoelectric element 10 is connected to the lower conductor 13 by the lead wire 12, and the lower conductor is connected to the lower conductor 13. Connect the lead wires 3a and 3b, and
A and 3b are covered with a shield wire 3 drawn from below the cylindrical case 11 and led out. With such a structure, when a drive signal is sent from the lead wires 3a and 3b of the ultrasonic transducer 1, the piezoelectric element 10 vibrates due to the piezo effect to generate ultrasonic waves. That is, the piezoelectric element 10 is
When driven by the burst signal as shown in FIG. 5, the ultrasonic transducer 1 vibrates according to the burst signal during the transmission time Ta and outputs ultrasonic waves, but after the burst signal is stopped. However, the vibration of the ultrasonic transducer 1 continues while being attenuated during the reverberation time Tb as shown in FIG. Therefore, conventionally, in order to shorten the reverberation time Tb, the holding member 5 has a structure in which the entire side surface of the ultrasonic transducer 1 is surrounded by the holding member 5 to pressurize it. In the structure surrounded by, the reverberation time Tb of the ultrasonic transducer 1 is shortened as shown in FIG.

[0003]

However, as shown in FIG. 4, the entire side surface of the ultrasonic transducer 1 is pressed by the holding member 5 so as to be held in a vibration-proof state, and then a housing formed of a molded product. When stored in 5, the vibration generated from the side surface of the ultrasonic vibrator 1 is transmitted to the housing 4 side through the holding member 5, and the vibration generated here propagates through the holding member 5 and the ultrasonic vibrator 1 side. The reverberation time Tb is returned and becomes unstable due to such vibration interference, and the reverberation time Tb becomes long as shown in FIG. 7, resulting in a reduction in short range resolution. There was a problem. An object of the present invention is to solve the above-mentioned problems, and even when the holding member of the ultrasonic vibrator is housed in a housing made of a molded product, vibration interference which is an unstable element is generated. It is an object of the present invention to provide an ultrasonic sensor with improved short-range resolution by suppressing and improving reverberation characteristics.

[0004]

According to the present invention, in order to achieve the above object, a convex ridge is formed inside so that only the antinode portion of the side surface of an ultrasonic vibrator that vibrates when ultrasonic waves are generated. It has a structure in which the ultrasonic transducer is surrounded by a holding member provided with a portion.

[0005]

According to the above structure, when the ultrasonic wave is generated from the ultrasonic vibrator, only the antinode portion of the side surface of the ultrasonic vibrator, which vibrates at the same time as the vibration of the front surface, that is, the large amplitude portion is formed in the holding member. Since it has a structure that suppresses vibration by applying pressure with the raised ridges, the vibration generated from the side surface of the ultrasonic transducer is transmitted to the housing of the molded product via the holding member,
Since it is possible to prevent the vibration here from interfering with the side surface of the ultrasonic transducer, the instability of reverberant vibration is eliminated.

[0006]

EXAMPLE An example of the present invention will be described below. FIG. 1 is a view showing a structure of a holding member showing an essential part of the present invention, and FIG. 2 shows a sectional structure in a state where an ultrasonic transducer is housed in the holding member. As shown in the figure, the holding member 2 is made of a rubber material or the like having excellent anti-vibration properties, has an opening 2a formed at its tip, and a shielded wire 3 led out from below the ultrasonic vibrator 1 at the center of its lower end. Hollow part 2b having a hole 2c formed therethrough
Is formed on the inner peripheral surface of the opening 2a, and when an ultrasonic wave is output from the front surface of the ultrasonic transducer 1, a convex portion that pressurizes and holds the abdominal portion of the side surface. 2a is formed. Here, as shown in FIG. 3, the ultrasonic transducer 1 vibrates so that, when ultrasonic waves are generated, three belly parts with large amplitude and two knot parts with small amplitude appear from the side surface. In the illustrated example, the antinode portion of the ultrasonic transducer 1 that is the closest to the piezoelectric element 10 and has a large amplitude is the ridge 2a described above, and the antinode portion of the lower end of the ultrasonic transducer 1 is It is pressure-held at the bottom corner 2d of the holding member 2. Further, in the structure shown in FIG. 1, when the ultrasonic transducer 1 is housed in the holding member 2, the ridge portion 2
Since a gap 2e is formed between a and the bottom corner 2d,
Even if the side surface portion of the ultrasonic transducer 1 corresponding to the gap 2e vibrates, the vibration is prevented from being transmitted to the holding member 5 due to the existence of the gap 2e, and the reverberation time can be stabilized accordingly. Thus, according to the ultrasonic sensor of the present invention, instead of pressing and holding the entire side surface of the ultrasonic vibrator with the holding member as in the conventional structure, only the abdominal portion with large vibration is pressed and held. Therefore, the vibration is suppressed from being transmitted to the holding member when the side surface of the ultrasonic vibrator vibrates. Therefore, even if the ultrasonic transducer is housed in the holding member, and the holding member is housed in the molded product housing, the reverberation time is not unstable, and an ultrasonic sensor with a short reverberation time can be obtained at low cost and is stable. It is possible to have a close range resolution. Further, in the case of such a structure, even if the housing 4 vibrates due to an external factor, the protrusion 2 of the holding member 2
Since a is in pressure contact with the belly portion on the side surface of the ultrasonic vibrator 1, the vibration of the housing 4 is not propagated to the ultrasonic vibrator 1. Therefore, the vibration of the housing 4 is less likely to be adversely affected, and malfunction due to external factors can be prevented.

[0007]

As described above, according to the present invention, since the holding member presses only the portion of the side surface of the ultrasonic vibrator where the vibration becomes large, it is housed in the housing. Reverberation time can be shortened,
Therefore, the short range resolution is improved and the short range blind spot is also reduced. In addition, compared to the conventional structure, the contact area between the side surface of the ultrasonic transducer and the holding member is reduced, so the frictional force at this portion is also reduced and the ultrasonic transducer can be easily inserted into the holding member. Workability at the time is also improved.

[Brief description of drawings]

FIG. 1 is a semi-cut vertical sectional structural view of a holding member which is a main part of an ultrasonic sensor of the present invention.

FIG. 2 is a diagram showing an embodiment of an ultrasonic sensor of the present invention,
FIG. 6 is a longitudinal sectional structural view showing a structure in which an ultrasonic transducer housed in a holding member is further housed in a housing.

FIG. 3 is a half-cut longitudinal sectional structural view of an ultrasonic transducer.

FIG. 4 is a view showing a vertical sectional structure of a conventional ultrasonic sensor.

FIG. 5 is a diagram showing a driving operation of an ultrasonic transducer.

6A and 6B are diagrams showing reverberation time of an ultrasonic transducer.

FIG. 7 is a diagram showing a problem in a conventional ultrasonic sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ultrasonic transducer 2 ... Holding member 2a ... Convex part 4 ... Molded article housing

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[Procedure amendment]

[Submission date] February 4, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

[0003]

However, as shown in FIG. 4, the entire side surface of the ultrasonic transducer 1 is pressed by the holding member 5 so as to be held in a vibration-proof state, and then a housing formed of a molded product. When stored in 5, the vibration generated from the side surface of the ultrasonic vibrator 1 is transmitted to the housing 4 side through the holding member 5, and the vibration generated here propagates through the holding member 5 and the ultrasonic vibrator 1 side. Returned due to such vibration interference,
The reverberation time Tb becomes rather unstable and the reverberation time Tb becomes long as shown in FIG. 7, resulting in a problem that the short-range resolution is deteriorated. An object of the present invention is to solve the above-mentioned problems, and even when the holding member of the ultrasonic vibrator is housed in a housing made of a molded product, vibration interference which is an unstable element is generated. It is an object of the present invention to provide an ultrasonic sensor with improved short-range resolution by suppressing and improving reverberation characteristics.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

[0004]

According to the present invention, in order to achieve the above object, a convex shape is formed inside so that only the antinode portion of the side surface of the ultrasonic transducer vibrating when ultrasonic waves are generated.
It has a structure in which the ultrasonic transducer is surrounded by a holding member provided with a portion .

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction content]

[0005]

According to the above structure, when the ultrasonic wave is generated from the ultrasonic vibrator, only the antinode portion of the side surface of the ultrasonic vibrator, which vibrates at the same time as the vibration of the front surface, that is, the large amplitude portion is formed in the holding member. Since it has a structure that suppresses vibration by pressing with the convex portion , the vibration generated from the side surface of the ultrasonic transducer is transmitted to the housing of the molded product through the holding member,
Since it is possible to prevent the vibration here from interfering with the side surface of the ultrasonic transducer, the instability of reverberant vibration is eliminated.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

[0006]

EXAMPLE An example of the present invention will be described below. FIG. 1 is a view showing a structure of a holding member showing an essential part of the present invention, and FIG. 2 shows a sectional structure in a state where an ultrasonic transducer is housed in the holding member. As shown in the figure, the holding member 2 is made of a rubber material or the like having excellent anti-vibration properties, has an opening 2a formed at its tip, and a shielded wire 3 led out from below the ultrasonic vibrator 1 at the center of its lower end. Hollow part 2b having a hole 2c formed therethrough
Is formed on the inner peripheral surface of the opening 2a, and a convex portion that pressurizes and holds the belly portion of the side surface when ultrasonic waves are output from the front surface of the ultrasonic transducer 1. 2a is formed. Here, as shown in FIG. 3, the ultrasonic transducer 1 vibrates so that, when ultrasonic waves are generated, three belly parts with large amplitude and two knot parts with small amplitude appear from the side surface. In the illustrated example, the portion of the ultrasonic transducer 1 that is closest to the piezoelectric element 10 in the antinode having a large amplitude is the above-mentioned convex portion 2a, and the lower end of the ultrasonic transducer 1 is in the antinode portion. It is pressure-held at the bottom corner 2d of the holding member 2. Further, in the structure shown in FIG. 1, when the ultrasonic transducer 1 is housed in the holding member 2, the convex portion 2
Since a gap 2e is formed between a and the bottom corner 2d,
Even if the side surface portion of the ultrasonic transducer 1 corresponding to the gap 2e vibrates, the vibration is prevented from being transmitted to the holding member 5 due to the existence of the gap 2e, and the reverberation time can be stabilized accordingly. Thus, according to the ultrasonic sensor of the present invention, instead of pressing and holding the entire side surface of the ultrasonic vibrator with the holding member as in the conventional structure, only the abdominal portion with large vibration is pressed and held. Therefore, the vibration is suppressed from being transmitted to the holding member when the side surface of the ultrasonic vibrator vibrates. Therefore, even if the ultrasonic transducer is housed in the holding member, and the holding member is housed in the molded product housing, the reverberation time is not unstable, and an ultrasonic sensor with a short reverberation time can be obtained at low cost and is stable. It is possible to have a close range resolution. Further, in the case of such a structure, even if the housing 4 vibrates due to an external factor, the convex portion 2 of the holding member 2
Since a is in pressure contact with the belly portion on the side surface of the ultrasonic vibrator 1, the vibration of the housing 4 is not propagated to the ultrasonic vibrator 1. Therefore, the vibration of the housing 4 is less likely to be adversely affected, and malfunction due to external factors can be prevented.

Claims (1)

[Claims] 1. A structure in which an ultrasonic vibrator is surrounded by a holding member having an opening for transmitting and receiving ultrasonic waves from the side surface and then the holding member is housed in a housing made of a molded product. The ultrasonic sensor has a structure in which a convex streak is provided inside the holding member so that only the antinode of the side surface of the ultrasonic vibrator is subjected to vibration isolation when an ultrasonic wave is generated.