JPH10206529A - Ultrasonic transmitter-receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To downsize and improve the short-range detection capability. SOLUTION: The transmitter-receiver contains an ultrasonic vibrator 22 having a transmission case that is equipped with a transmission piezoelectric element and is closed by a transmission diaphragm at one end of its cylindrical body, a reception case that is equipped with a receiving piezoelectric element and is closed by a reception diaphragm at one end of its cylindrical body, and a connecting piece that connects the transmission case and the receiving case, is stored in a housing 21. In such case, the transmission case and the receiving case are connected only at parts near the opening of the transmission case and the opening of the reception case by the connecting piece. A cushioning material is placed in a clearance between the transmission case and the reception case connected by the connection piece.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic transducer for transmitting an ultrasonic signal and detecting a presence of an obstacle by receiving a reflected wave from the obstacle.

[0002]

2. Description of the Related Art FIG. 5 is a view for explaining the principle of an ultrasonic sensor.
FIG. 6 is a sectional view showing a conventional ultrasonic transducer, and FIG. 7 is a sectional view showing an ultrasonic transducer of the conventional ultrasonic transducer.
FIG. 8 is an explanatory diagram of a transmitted / received signal of a conventional ultrasonic transducer. FIG. 8A is an explanatory diagram of a transmitted signal, and FIG. 8B is an explanatory diagram of a received signal. FIG. 9 is a sectional view showing another conventional ultrasonic transducer.

[0005] As shown in FIG. 5, the principle of the ultrasonic sensor is as follows.
The distance L to the obstacle A is detected based on the time required for the ultrasonic signal B transmitted to the front space to be reflected by the obstacle A and returned again.

Meanwhile, in a conventional ultrasonic sensor, an ultrasonic transducer 1 as shown in FIG. 6 is used. That is, the ultrasonic transducer 1 includes a housing 2 made of a molded product made of resin, an ultrasonic vibrator 3 housed in the housing 2, and a circuit block 4. The housing 2 includes a horn portion 2a for efficiently transmitting ultrasonic waves in a forward beam. The ultrasonic vibrator 3 is a part that converts an electric signal into mechanical vibration and directly vibrates air, or converts an air vibration into mechanical vibration and converts it into an electric signal. The housing 2 is housed in the housing 2 with a holding member 5 such as silicon rubber having an opening at a portion to be opened. The circuit block 4 supplies an electric signal to the ultrasonic vibrator 3 via the shield wire W and amplifies an electric signal input from the ultrasonic vibrator 3.

[0005] Ultrasonic transducers 3, details as shown in Figure 7, one end of the tubular body and the aluminum case 3a which is closed by the thin plate portion 3a _1, the inner surface of the thin plate portion 3a ₁ of the case 3a A small plate-shaped piezoelectric element 3b to be attached and a case 3
and a circuit board 3c that covers the opening side of a.
The shield wire W is connected to the circuit board 3c.
c and the lead wire 3d ₂ of hot-side lead wire 3d ₁ and the ground side is drawn out from the lead wire 3d ₁ the piezoelectric element 3b
Connected to lead wires 3d ₂ is connected to the thin plate portion 3a ₁ in the vicinity of the piezoelectric element 3b.

[0006] The conventional ultrasonic transducer 1 configured as described above has an ultrasonic signal transmission / reception characteristic as shown in FIG. That is, when transmitting ultrasonic waves by vibrating the thin plate portion 3a ₁ by applying a driving signal as shown in FIG. 8 (a) to the piezoelectric element 3b, the reverberation signal by reverberation oscillation as shown in FIG. 8 (b) Appears after the drive signal, and the reflected wave from the obstacle A returns after T = 2 L / V seconds from the start of driving the piezoelectric element 3b. Here, V is the speed of sound.

[0007]

Therefore, the shorter the distance between the ultrasonic transducer 1 and the obstacle A in FIG.
The reflected wave from the obstacle A in FIG. 8B gradually approaches the reverberation signal, and the reflected wave eventually hides in the reverberation signal. Therefore, in the case of an ultrasonic sensor including the conventional ultrasonic transducer 1 having a configuration as shown in FIG.
If the distance between the ultrasonic transducer 1 is too small, the obstacle A cannot be detected.

Therefore, in order to prevent a reduction in short-range detection ability due to reverberation vibration of the ultrasonic vibrator 3, an ultrasonic transducer using a separate-type ultrasonic vibrator that does not generate reverberation has been devised. Fig. 9 shows the structure of the ultrasonic transducer.
Shown in An ultrasonic transducer 6 shown in FIG. 9 includes a housing 7 made of a molded product made of resin, an ultrasonic vibrator 8 a for transmitting and an ultrasonic vibrator 8 for receiving, which are housed in the housing 7.
b and a circuit block 9.

The housing 7 includes a horn 7a for efficiently transmitting ultrasonic waves in a forward beam and a horn 7b for efficiently receiving ultrasonic waves from the front. The ultrasonic vibrator 8a converts an electric signal into mechanical vibration and directly vibrates air, and the ultrasonic vibrator 8b converts air vibration into mechanical vibration and converts it into an electric signal. . Each of the ultrasonic transducers 8a and 8b
It has the same configuration as the ultrasonic transducer shown in FIG. 7, and is housed in the housing 7 with a holding material 10 such as silicon rubber, which is open at a portion where ultrasonic waves are input and output. The circuit block 9 supplies an electric signal to the ultrasonic vibrator 8a via the shield wire W or amplifies an electric signal input from the ultrasonic vibrator 8b.

However, the ultrasonic transducer 6 shown in FIG. 9 is compared with the ultrasonic transducer 1 using the ultrasonic vibrator 3 having a transmitting / receiving structure as shown in FIG. ,
Although the ultrasonic vibrator 8a and the ultrasonic vibrator 8b are separate bodies, the influence of reverberation vibration is reduced, so that the short-range detection capability is improved. However, two ultrasonic vibrators, two holding members, and two horn parts are used. It has to be provided, and there is a problem that not only is it difficult to assemble and the cost is increased, but also the size becomes large.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide an excellent ultrasonic transducer which can be reduced in size, is inexpensive, and has improved short-distance detection capability. Is to provide.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to the invention described in claim 1, wherein one end of a cylindrical body provided with a piezoelectric element for transmitting waves is attached to a diaphragm for transmitting waves. A transmitting case closed at the end, a receiving case closed at one end of the tubular body provided with the receiving piezoelectric element, a transmitting case and a receiving case. An ultrasonic transducer having a connecting piece for connecting the parts in parallel with each other, the ultrasonic transducer being housed in a housing, the connecting piece being used to receive the ultrasonic vibrator near the opening of the case for transmitting wave. The wave transmitting case and the wave receiving case are connected only in the vicinity of the opening of the wave case.

[0013] The invention according to claim 2 is characterized in that a cushioning material is interposed in a gap between the transmitting case and the receiving case connected by the connecting piece.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an ultrasonic transducer according to the present invention will be described below in detail with reference to FIGS. 1 to 3 and another embodiment based on FIG. .

FIG. 1 is a sectional view showing an ultrasonic transducer. 2A and 2B are views showing an ultrasonic transducer, FIG. 2A is a plan view, and FIG. 2B is a sectional view. FIG. 3 is a side view illustrating the vibration mode. FIG. 4 is a diagram showing an ultrasonic transducer of an ultrasonic transducer according to another embodiment, and FIG.
Is a plan view, and FIG. 4B is a sectional view.

The ultrasonic transducer 20 includes a housing 21 made of a resin molded product, an ultrasonic vibrator 22 housed in the housing 21, and a circuit block 23. The housing 21 includes a horn portion 21a for efficiently transmitting ultrasonic waves in a forward beam. Ultrasonic transducer 2
Numeral 2 is a part that converts an electric signal into mechanical vibration to directly vibrate air, or a part that converts air vibration into mechanical vibration and then converts it into an electric signal. Is housed in the housing 21 with a holding member 24 such as silicon rubber having an opening. The circuit block 23
And supplies an electric signal to the ultrasonic transducer 22 via the shielded wire W _1, via a shielded cable W ₂ ultrasonic transducer 22
Or amplify the electrical signal input from the

The ultrasonic transducer 22, specifically as shown in FIG. 2, the aluminum transmitting a case portion 22a which closes the one end of the tubular body at transmitting diaphragm 22a _1, the tubular body Receiving case 22b made of aluminum having one end closed by a receiving vibration plate 22b _1, and a transmitting case 22a
Connecting portion 22c for connecting the wave receiving case portion 22b to the wave receiving case portion 22b
A small plate-like transmitting piezoelectric element 22d attached to the inner surface of the wave transmitting diaphragm 22a ₁ of the wave transmitting case 22a, and the inner surface of the wave receiving diaphragm 22b ₁ of the wave receiving case 22b. , A circuit board 22f covering the opening of the wave transmitting case 22a, and a circuit board 22g covering the opening of the wave receiving case 22b.
It is composed of

[0018] The circuit board 22f is connected to the shield wire W _1, the circuit board 22g is connected shielded wire W _2. From the circuit board 22f and the lead wire 22h ₂ active line of the lead wire 22h ₁ and the ground side is pulled, the lead wire 22h ₁ is connected to the transmitting piezoelectric element 22 d, leads 2
2h ₂ is the transmitting plate 2 near the transmitting piezoelectric element 22d.
To connect to the 2a _1. Further, a lead wire 22i ₂ leads 22i ₁ and the ground side of the hot-side is led out from the circuit board 22 g, the piezoelectric element 22e lead wire 22i ₁ is received wave
And the lead wire 22i ₂ is connected to the wave receiving diaphragm 22b ₁ near the wave receiving piezoelectric element 22e.

The ultrasonic transducer 22 is characterized by the following configuration. That is, the wave transmitting diaphragm 22
To transmit ultrasonic waves from a ₁ must be vibrates the transmitting case for section 22a in the ultrasonic frequency to be used,
It is necessary to vibrate the transmitting piezoelectric element 22d near the resonance frequency of the transmitting case 22a. Also, to receives ultrasonic waves reflected back at reception diaphragm 22b ₁ is
The receiving case portion 22b must be vibrated by an ultrasonic wave having a frequency to be used.

Therefore, the transmitting case 22a and the receiving case 22b are designed based on the frequency of the ultrasonic wave to be used. The transmitting case 22a and the receiving case 22b Are ultrasonic waves of the frequency to be used, and resonate in a mode in which the opening is exactly a node (minimum amplitude) as shown in FIG. Therefore, the connecting piece 22c
Thus, when the vicinity of the opening of the transmitting case 22a and the vicinity of the opening of the receiving case 22b are connected, the connection is made at a portion where the node (the amplitude becomes minimum) when resonating with the ultrasonic wave of the used frequency. It will be not transmitted to the reception for the case portion 22b vibration via the coupling piece 22c of transmitting a case portion 22a at the time of transmitting ultrasonic waves from the transmitting diaphragm 22a _1, by the reverberation oscillations The influence can be reduced, and the short-distance detection ability can be improved.

In a conventional ultrasonic transducer having improved short-range detection capability, an ultrasonic vibrator, a holding material such as silicon rubber for holding the ultrasonic vibrator, and a horn portion provided on the housing are provided. Had to be provided two each. On the other hand, in the ultrasonic wave transmitter / receiver 20, since the wave transmitting case 22a and the wave receiving case 22b are integrally connected via the connecting piece 22c, the ultrasonic vibrator 22 The holding member 24 such as silicon rubber for holding the ultrasonic vibrator 22 and the horn 21a provided on the housing 21 need only be provided one by one, so that the number of parts and the number of assembling steps can be reduced, and the cost can be reduced. The size can be reduced.

As shown in FIG. 4, when a cushioning material 25 such as sponge rubber for absorbing and blocking ultrasonic waves and vibrations is interposed in the gap between the transmitting case 22a and the receiving case 22b, Further, it is possible to make it difficult for the vibration of the wave transmitting case portion 22a to be transmitted to the wave receiving case portion 22b, and to provide an excellent ultrasonic transducer which can be reduced in size, is inexpensive, and has improved near-field detection capability.

[0023]

According to the first aspect of the present invention, since the transmitting case and the receiving case are connected via the connecting piece, the number of parts and the number of assembling steps can be reduced. The cost can be reduced, the shape can be reduced, and
At the node of the vibration mode of the transmission case by the ultrasonic wave of the frequency to be used, the transmission case and the reception case are connected via the connection piece, so that the transmission It is possible to provide an excellent ultrasonic transducer which is less likely to transmit vibration of the case for transmitting waves to the case for receiving waves, can be reduced in size, is inexpensive, and has improved short-distance detection capability.

According to the second aspect of the present invention, the cushioning material is interposed in the gap between the wave transmitting case portion and the wave receiving case portion. It is possible to make it difficult to transmit the vibration of the receiving case portion to the receiving case portion, and to provide an excellent ultrasonic transducer with improved short-range detection capability.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an ultrasonic transducer according to an embodiment of the present invention.

FIG. 2 is a view showing an ultrasonic transducer of the ultrasonic transducer.

FIG. 3 is a side view for explaining a vibration mode of an ultrasonic transducer of the ultrasonic transducer.

FIG. 4 is a cross-sectional view illustrating an ultrasonic transducer of an ultrasonic transducer according to another embodiment of the present invention.

FIG. 5 is a diagram illustrating the principle of an ultrasonic sensor.

FIG. 6 is a cross-sectional view showing a conventional ultrasonic transducer.

FIG. 7 is a cross-sectional view showing an ultrasonic transducer of a conventional ultrasonic transducer.

FIG. 8 is an explanatory diagram of a transmitted / received signal of a conventional ultrasonic transducer.

FIG. 9 is a cross-sectional view showing another conventional ultrasonic transducer.

[Explanation of symbols]

Reference Signs List 20 ultrasonic transmitter / receiver 21 housing 22a transmitting case 22a ₁ transmitting diaphragm 22b receiving case 22b ₁ receiving diaphragm 22d transmitting piezoelectric element 22e receiving piezoelectric element 22c connecting piece 25 cushioning material

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[Procedure amendment]

[Submission date] April 1, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction contents]

However, the ultrasonic transducer 6 shown in FIG. 9 is compared with the ultrasonic transducer 1 using the ultrasonic vibrator 3 having a transmitting / receiving structure as shown in FIG. ,
Although the ultrasonic transducer 8a and the ultrasonic vibrator 8b is short range detection capability for the influence of the sentence reverberation oscillation are separate can be reduced is improved, two ultrasonic transducers, the holding member and the horn portion, respectively must be provided One does not only difficult assembly costly shape disadvantageously becomes large.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction contents]

The ultrasonic transducer 22 is characterized by the following configuration. That is, the wave transmitting diaphragm 22
To transmit ultrasonic waves from a ₁ must be vibrates the transmitting case for section 22a in the ultrasonic frequency to be used,
It is necessary to vibrate the transmitting piezoelectric elements 22d in the vicinity of the resonance frequency of the transmitting case for section 22a. Also, to receives ultrasonic waves reflected back at reception diaphragm 22b ₁ is
The receiving case portion 22b must be vibrated by an ultrasonic wave having a frequency to be used.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction contents]

In a conventional ultrasonic transducer having improved short-range detection capability, an ultrasonic vibrator, a holding material such as silicon rubber for holding the ultrasonic vibrator, and a horn portion provided on the housing are provided. , it has been necessary to provide one not two, respectively. On the other hand, in the ultrasonic wave transmitter / receiver 20, since the wave transmitting case 22a and the wave receiving case 22b are integrally connected via the connecting piece 22c, the ultrasonic vibrator 22 , the holding member 24, such as silicone rubber that holds the ultrasonic transducer 22 and, since the horn portion 21a provided on the housing 21 need only provide one at a time can reduce the number of components and assembly steps, cost reduction And the size can be reduced.

Claims (2)

[Claims] 1. A wave transmitting case portion having a wave transmitting piezoelectric element and one end of a cylindrical body closed by a wave transmitting diaphragm, and a wave receiving piezoelectric element having one end of a cylindrical body for wave receiving. An ultrasonic transmitter / receiver having a housing for receiving an ultrasonic transducer having a receiving case closed by a diaphragm and a connecting piece for connecting the transmitting case and the receiving case in parallel. In the wave device, the connection piece connects the transmission case and the reception case only in the vicinity of the opening of the transmission case and in the vicinity of the opening of the reception case. An ultrasonic transducer, characterized in that: 2. The ultrasonic transducer according to claim 1, wherein a buffer material is interposed in a gap between the transmitting case and the receiving case connected by the connecting piece.