JPH0439037B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improvements in ultrasonic transducers used in devices using ultrasonic waves, such as ultrasonic underwater telephones and fish finders.

[Conventional technology]

Various types of ultrasonic transducers have been used to transmit and receive ultrasonic waves, and ring-shaped electrostrictive transducers are generally used in ultrasonic underwater telephones, etc. There is.

As shown in FIG. 5, such a conventional ultrasonic transducer is constructed by molding a ring-shaped vibrator 2 in a urethane mold 1, and placing the vibrator 2 on a hard pedestal with a vibration isolating material 3 in between. 4, and further this hard pedestal is attached to a mounting portion of a watertight container 5 housing a transmitter/receiver for an ultrasonic underwater telephone.

[Problem that the invention seeks to solve]

The above-mentioned vibrator is molded to prevent the impedance from decreasing when using this underwater telephone etc. underwater, and this vibrator performs radial breathing vibration, and cannot generate ultrasonic waves by itself. Shows omnidirectionality in the transmission and reception of vibrations.

However, as shown in FIG.
If the shape of the attachment part of the watertight container 5 is formed into a flat planar shape, the sensitivity will deteriorate when receiving sound waves from a certain direction θ. This direction θ is an odd number ((n+1)λ/ 2, λ: wavelength,
n: an integer). This is because the sound waves of the two paths in this direction interfere, resulting in poor sensitivity.

In this way, with conventional transducers, as shown in Figure 6, in a directivity pattern that represents the points at which the reception sensitivity of sound waves is maximum for various azimuths as a continuous curve, it is possible to The sensitivity is extremely low, which is disadvantageous for use as an underwater telephone.

This invention was made in view of the current state of the technology of ultrasonic transducers, and its purpose is to improve the hard pedestal and mounting portion of a ring-shaped vibrator used as an ultrasonic transducer. An object of the present invention is to provide an ultrasonic transducer in which the region of minimum sensitivity has almost no effect on the transmitting and receiving functions by improving the shape of the ultrasonic transducer.

[Means for solving problems]

Therefore, as a means to solve the above problems, the present invention includes a vibrator for transmitting and receiving ultrasonic waves, a mold to make the vibrator watertight underwater, and a vibrator that is connected to the vibrator through a vibration-proofing material such as cork. The rigid pedestal is provided with a truncated cone shape having an inclined surface at a predetermined angle, and the mounting portion to which the hard pedestal is attached is also formed in a truncated cone shape.

[Effect]

In this ultrasonic transducer configured as described above, the direct ultrasonic wave received through the mold is hard even if there is another parallel incident ultrasonic wave incident from the same direction. Since the shape of the pedestal and the mounting part is formed into a truncated cone shape with an inclined surface, the ultrasonic signal reflected on this inclined surface is reflected near the direction of the original incident wave, and it is not hard as before. Ultrasonic waves reflected by the pedestal rarely interfere with direct waves and minimize reception sensitivity.

Therefore, omnidirectional reception sensitivity can be obtained within a range of at least ±90°, so that sufficient reception sensitivity can be obtained in underwater communication using ultrasonic waves.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a device in which a transducer according to the present invention is attached to the top of a container containing a transceiver for communicating underwater. 1 is a urethane mold to make the transducer watertight, 2 is a ring-shaped vibrator, 3 is a vibration isolating material made of cork, etc., 4 is a hard pedestal, and 5 is a mounting for attaching the hard pedestal 4. 6 is a container that houses a transmitter/receiver.

The provision of a mold 1, a vibrator 2, and a vibration isolator 3 is the same as in a conventional transducer. However, the shapes of the hard pedestal 4 and the mounting portion 5 are different from those of the conventional one. The hard pedestal 4 has a truncated cone shape with an inclined surface at a predetermined angle, and the mounting portion to which this hard pedestal is attached is formed in a truncated cone shape. Most preferably, the angle of inclination of the inclined surface with respect to the horizontal plane is about 45°. Note that this hard pedestal 4 is generally made of metal, and is also made of metal in this embodiment, but it can also be made of hard materials other than ultrasonic absorbing materials, such as plastic and Bakelite. Good too.

FIG. 2 is an example of a transceiver using the transducer described above. This transceiver is a known transceiver equipped with an FM modulation/demodulation circuit, and includes a microphone 11, an amplifier 12, and an FM modulation circuit 1 for transmission.
3, power amplifier 14, transmission/reception switch 15,
Reception amplifier 16 and FM demodulation circuit 1 for reception
7, an amplifier 18, and a speaker 19, and is used, for example, as an underwater telephone.

The operation of this embodiment configured as described above is as follows.

The mold 1, the vibrator 2, and the vibration isolator 3 have the same structure as before, but the hard base 4 and the mounting part 5 are formed in a truncated cone shape with an inclined surface, so as shown in FIG. Even if ultrasonic waves a and a' are incident from a certain angle of azimuth θ, the ultrasonic wave of a' will be reflected by the inclined surface and will be reflected near the direction of the original path of a', and as in the conventional case, the ultrasonic wave will be This prevents reflected waves of odd numbers having a half wavelength from interfering with the ultrasonic wave a. Therefore, the pattern of the ultrasonic reception sensitivity curve can be expressed as
As shown in the figure, the area of minimal sensitivity becomes narrower and the area of omnidirectionality expands. Even if there is a region of minimal sensitivity as shown in Figure 4, at least the omnidirectional direction can be secured at ±90° or more, so in practice, using this omnidirectional range will be sufficient for practical use. can get.

〔effect〕

As explained in detail above, in the transducer according to the present invention, the shape of the hard base and the mounting part are shaped like a truncated cone with an inclined surface, so as to prevent reflected waves of ultrasonic waves from interfering with each other and reducing sensitivity. , it is possible to obtain practically sufficient omnidirectional characteristics.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a state in which an ultrasonic transducer according to the present invention is attached to a container housing an ultrasonic transceiver for underwater communication, Fig. 2 is a circuit diagram of an example of an ultrasonic transceiver, and Fig. 3 4 are diagrams showing the incident state of ultrasonic waves and patterns of sensitivity curves, and FIGS. 5 and 6 are diagrams showing conventional ultrasonic transducers and patterns of their sensitivity curves. 1... Mold, 2... Vibrator, 3... Vibration isolating material, 4... Hard pedestal, 5... Mounting part.

Claims (1)

[Claims] 1. A transducer for transmitting and receiving ultrasonic waves, a mold for making the transducer watertight underwater, and a hard pedestal for mounting the transducer through a vibration isolating material,
An ultrasonic transducer characterized in that the hard pedestal has a truncated cone shape with an inclined surface at a predetermined angle, and a mounting portion to which the hard pedestal is attached is also formed in a truncated cone shape. 2. The ultrasonic transducer according to claim 1, wherein the vibrator is a ring-shaped electrostrictive vibrator. 3. The ultrasonic transducer according to claim 1, wherein the mold is a urethane mold.