JPH0320788Y2 - - Google Patents

Description

[Detailed description of the invention] <Field of the invention> The present invention is an ultrasonic wave device that is used to detect the presence or absence of an object such as a vehicle by periodically transmitting ultrasonic waves and receiving the reflected waves. Regarding transducers.

<Prior art and its problems> Generally, in an ultrasonic detector that periodically transmits ultrasonic waves and receives the reflected waves to detect the presence or absence of an object such as a vehicle, one ultrasonic transmitter/receiver is used. Ultrasonic waves are transmitted and received by a transducer. 6th
This figure is a perspective view of a conventional ultrasonic transducer, and FIG. 7 is a partially cutaway perspective view of the vibrator portion of FIG. 6. In these figures, reference numeral 1 is a cylindrical ring vibrator, 2 is an equalizer that is an internal reflector, and 3 is an equalizer that is an internal reflector.
is a horn which is an external reflector, and the ultrasonic wave from ring vibrator 1 is transmitted to equalizer 2 and horn 3.
is converted into a plane wave and radiated in the direction indicated by the arrow in FIG.

The ring vibrator 1 of this ultrasonic transducer is mainly an electrostrictive vibrator or a piezoelectric vibrator, and these have resonance characteristics. Therefore, when ultrasonic waves are transmitted periodically as shown in FIG. 8A,
As shown in Figure B, even after the transmission ends, the damped oscillation due to the transient phenomenon continues and reverberation wave A is generated.
During the time t1 (reverberation time) until the damped vibration disappears, the reflected waves cannot be received and detected, which limits the detection ability of the ultrasonic detector at short distances.

This reverberant wave A is generated by the radial vibration of the ring vibrator 1 and the secondary vibration in the axial direction. This axial vibration is much shorter and weaker than the radial vibration, so it is normally absorbed by the reverberant wave due to the radial vibration and can be ignored. However, if the reverberation time based on the radial vibration is shortened by electrical or mechanical means, the reverberation wave due to the axial vibration and the radial direction over time t2, as shown in FIG. The reverberant waves caused by the vibrations begin to interfere with each other. For this reason, reverberation waves caused by vibrations in the axial direction cannot be ignored, and in order to effectively shorten the reverberation time, it is necessary to shorten the reverberation waves in the axial direction.

<Purpose of the invention> The present invention was made in view of the above points, and the purpose is to shorten the reverberation time as much as possible by shortening the reverberation waves mainly in the axial direction of the ring vibrator. shall be.

<Configuration and Effects of the Invention> In order to achieve the above-mentioned purpose, the present invention provides an ultrasonic transducer equipped with a ring vibrator, which transmits ultrasonic waves and receives reflected waves thereof. A ring-shaped damped vibration regulating means is provided, and the regulating means is arranged in contact with the free end side of the ring vibrator in a state where stress is applied to the ring vibrator by the elastic body. Therefore, according to the present invention, the damped vibration of the ring oscillator after transmitting ultrasonic waves is effectively regulated by the regulating means, thereby shortening the reverberation time. An ultrasonic detector capable of detecting at a distance can also be obtained.

<Description of Embodiments> Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of an ultrasonic transducer according to an embodiment of the present invention, and FIG. 2 is an enlarged perspective view of the ring vibrator shown in FIG. 1, corresponding to FIGS. 6 and 7. Parts are given the same reference numerals. In these figures, 1 is a cylindrical ring vibrator whose one end is fixed to an equalizer 2' which is an internal reflector, 3 is a horn which is an external reflector, 4 is a lead-out cable, 5 is a packing, and 6 is a ring. This is a ring for positioning the vibrator 1. The ultrasonic wave from the ring vibrator 1 is converted into a plane wave by an equalizer 2' and a horn 3, and then transmitted. A reflected wave from a detected object such as a vehicle is collected by an equalizer 2' and a horn 3, and converted into a corresponding electric signal by a ring vibrator 1.

In the ultrasonic transducer of the present invention, the ring vibrator 1
A ring-shaped regulating means 7 is provided on the free end side of the ring transducer 1, which is placed in contact with the ring transducer 1 while applying stress to the ring transducer 1 by means of an elastic body, and regulates damped vibration of the ring transducer 1 after ultrasonic wave transmission. . In this embodiment, the regulating means 7 controls the ring vibrator 1 to
It consists of a rigid pressing member 8 that presses in the axial direction (direction shown by arrow 10), and an annular elastic member 9 (elastic body) interposed between the pressing member 8 and the ring vibrator 1. . The pressing member 8 is made of metal and consists of an annular portion 8a having the same diameter as the ring vibrator 1, a support portion 8b integral with the annular portion 8a, and a screw 8c.
is fixed to the equalizer 2' with an appropriate pressing force. A shaft portion 2'a is formed in the equalizer 2' in order to tighten and fix the pressing member 8.
The elastic member 9 between the annular portion 8a of the pressing member 8 and the ring vibrator 1 is made of rubber or the like having a large elastic modulus, and is formed to have the same diameter as the ring vibrator 1.

In this way, by applying an appropriate stress to the ring vibrator 1 in the axial direction as shown by the arrow 10 through the elastic member 9, the ring vibrator 1 is
Reverberation energy based on damped vibration in the axial direction is absorbed and consumed by the elastic member 9 having a large elastic modulus.

FIG. 3 is a waveform diagram for explaining the effect of shortening the reverberant wave A according to the embodiment of FIG.
is a waveform diagram showing ultrasonic wave transmission when the reverberation wave due to the radial damped vibration of the ring vibrator 1 is shortened by conventional electrical or mechanical means,
FIG. 3B is a waveform diagram of the detection gate signal corresponding to FIG. 3A, and FIG. 3D is a waveform diagram of the detection gate signal corresponding to FIG.
Furthermore, it is a waveform diagram showing transmission of ultrasonic waves when damped vibration in the axial direction is suppressed by this embodiment,
FIG. 3C is a waveform diagram of the detection gate signal corresponding to FIG. 3D. The ultrasonic transducer is in a state where it can receive reflected waves while the detection gate signals shown in FIGS. 3B and 3C are at a high level.

According to this embodiment, by applying an appropriate stress to the ring vibrator 1 in its axial direction via the elastic member 9, the reverberation energy based on the axially damped vibration of the ring vibrator 1 is reduced to a modulus of elasticity. Since it is absorbed and consumed by the large elastic member 9, there is no interference between the reverberant waves due to the radial vibration and the reverberant wave due to the axial vibration over the time t2 shown in FIG. 3A, and the reverberation time is shortened. The state shown in FIG. 3D is reached. As a result, the detection gate signal becomes high level quickly by Δt as shown in FIG. 3B to FIG. 3C, that is, the ultrasonic transducer becomes able to receive reflected waves, and It becomes possible to detect reflected waves from a short distance from the wave device. This shortened time Δt is
This is approximately 3 msec, which is approximately 3 msec compared to the case where no reverberation wave suppression measures were taken, as shown by the imaginary line in Figure 3D.
Reduced by 6msec. This is approximately 1 m when converted into distance, and the detection characteristics of reflected waves from a short distance are greatly improved.

FIG. 4 is a block diagram showing the overall configuration of an ultrasonic detector to which the embodiment of FIG. 1 is applied. In the figure, 11 is a synchronization signal generation circuit for synchronizing the operation of the entire circuit, and 12 is a drive transformer 17.
This is a wave transmitting circuit that provides a driving signal to the ultrasonic transducer 17 of this embodiment via the ultrasonic wave transmitter/receiver 17 of this embodiment. Ultrasonic transducer 1
The ultrasonic waves transmitted from the ultrasonic transducer 7 return to the ultrasonic transducer 17 after being reflected by a sensing object such as a vehicle 18 . The ultrasonic wave received by the ultrasonic transducer 17 is converted into an electric signal and output to the limiter circuit 15 via the drive transformer 16.
The electric signal is amplitude limited by the limiter circuit 15, amplified to a predetermined level by the amplifier circuit 13, and then subjected to predetermined processing by the processing circuit 14. Note that the radial vibration is electrically suppressed by the radial reverberation wave suppression circuit 19.

FIG. 5 is a perspective view corresponding to FIG. 2 of another embodiment of the present invention, and corresponding parts are given the same reference numerals. In this embodiment, focusing on the property that the ring vibrator 1 vibrates in the radial direction, it also vibrates secondarily in the axial direction, and is configured to absorb and consume the reverberant energy in the axial direction in the radial direction. ing.

That is, in this embodiment, the ring vibrator 1 is used as a regulating means for regulating the damped vibration of the ring vibrator 1.
an elastic tightening member 7' that tightens the ring oscillator radially inward (in the direction indicated by arrow 10').
(elastic body) is provided on the free end side of the ring vibrator 1. This tightening member 7' is made of a material with a high elastic modulus, such as rubber or thermoplastic elastomer, and its inner diameter is set to be slightly smaller than the outer diameter of the ring vibrator 1. This tightening member 7' is fitted onto the free end side of the ring vibrator 1, and the ring vibrator 1 is tightened inward in the radial direction with an appropriate stress.

As a result, the axial reverberation energy transmitted in the radial direction is absorbed and consumed by this tightening member 7', and the axial reverberation wave becomes shorter. Note that, in this embodiment, the equalizer 2 differs from the previous embodiments in that no shaft portion is formed, and the equalizer 2 is constructed in the same manner as the conventional example.

[Brief explanation of drawings]

Fig. 1 is a perspective view of one embodiment of the present invention, Fig. 2 is an enlarged perspective view of the vicinity of the ring vibrator in Fig. 1, and Fig. 3 is an ultrasonic wave for explaining the effect of the embodiment of Fig. 1. 4 is a block diagram of the entire ultrasonic detector, FIG. 5 is a perspective view corresponding to FIG. 2 of another embodiment of the present invention, and FIG. 6 is a diagram of the conventional example. FIG. 7 is a partially cutaway perspective view of FIG. 6, and FIG. 8 is an ultrasonic waveform diagram. 1...Ring vibrator, 7...Regulating means, 7'...
...Tightening member, 8...Press member, 9...Elastic member.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In an ultrasonic transducer equipped with a ring vibrator, which transmits ultrasonic waves and receives reflected waves thereof, a ring-shaped damped vibration regulation provided with an elastic body 1. An ultrasonic transducer characterized in that the regulating means is disposed in contact with a free end side of the ring vibrator in a state where stress is applied to the ring vibrator by the elastic body. (2) The regulating means includes a pressing member that presses the ring vibrator in the axial direction of the ring vibrator, and the elastic body is interposed between the pressing member and the ring vibrator. The ultrasonic transducer according to claim 1, characterized in that the ultrasonic transducer comprises: (3) The ultrasonic transmitter/receiver according to claim 1, wherein the elastic body comprises an elastic tightening member that tightens the ring vibrator inward in the radial direction of the ring vibrator. Wave equipment.