JP3065123B2 - High resolution measuring equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring device for underwater exploration, and more particularly to a device capable of measuring with high resolution.

[0002]

2. Description of the Related Art FIG. 1 shows an image detected by an ideal high-resolution fish finder, while FIG. 2 shows an image detected by a conventional fish finder. In FIG. 1, A is a bottomed fish in the vicinity of the seabed B, but in FIG. 2, the bottomed fish A ′ is in contact with the seabed B, and the middle fish C in FIG.
Are detected as two groups, but are detected only as one group without being separated in FIG. Then, plankton E is identified around upper fish D in FIG. 1, but in FIG. 2, it is difficult to distinguish between upper fish D ′ and plankton E ′. Further, the transmission line F 'in FIG.
The tail is longer.

As can be seen from the comparison of the tails, in order to obtain a high resolution, the ultrasonic waves oscillated from the ultrasonic transducer must have a pulse-like waveform as shown in FIG. For this purpose, as shown in FIG. 4, an ultrasonic electric signal having a short pulse width t of a half cycle of the operating frequency may be applied to the ultrasonic transducer.

As is well known, a signal as shown in FIG. 3 is composed of signals of extremely wide frequency components around a center frequency. Therefore, in order to radiate such an ultrasonic signal, It must be a broadband ultrasonic transducer.

However, since the ultrasonic vibrator resonates at a unique single frequency determined by its dimensions and the like, the band of ultrasonic waves that can be oscillated is narrow. Even if the electric signal shown in FIG. 4 is applied, the vibration cannot be faithfully followed by the signal waveform, and the state of the vibration becomes a dull waveform as shown in FIG. As described above, the conventional ultrasonic transducer having a narrow band cannot emit pulsed ultrasonic waves, and therefore obtains high resolution in a fish finder or various underwater measuring devices using such an ultrasonic transducer. It is not possible.

[0006]

Therefore, a technique for widening the band which has been conventionally performed on the ultrasonic vibrator will be described. In FIG. 6, a backing layer 62 is attached to the back surface of the disk-shaped ultrasonic vibrator 61 so as not to emit sound backward, and a matching layer 6 is provided on the radiation surface of the ultrasonic vibrator 61.
2 are bonded, and the density, thickness, and sound speed of the layers of the matching layer 63 and the backing layer 62 become parameters, and the radiation characteristics of the ultrasonic transducer 61 are broadened.

However, in this configuration, the matching layer 6 is provided on the radiation surface.
The efficiency of the emission and reception of ultrasonic waves is reduced due to the provision of (3). Further, not only does the ultrasonic transducer 61 have a wide band due to the bonding condition of the layers 62 and 63, but also these layers 62 and 63 are fixedly adhered to the ultrasonic transducer 61, so that they are manufactured once. However, there are many problems and limitations in practical use.

FIG. 7 shows that a broadband matching electric circuit 64 composed of L and C is inserted in the drive circuit of the ultrasonic vibrator 61. It is known that the sound wave oscillator 62 has a wider band. However, this configuration also has the following problems.

FIG. 8 shows the impedance characteristics of the ultrasonic transducer 61 shown in FIG. The frequencies f ₁ and f _{2 at the} resonance point where the impedance is minimized are based on the thickness L ₁ and the diameter L ₂ of the ultrasonic vibrator 61, and this ultrasonic vibrator 61 is based on the thickness L ₁ using resonant mode frequencies f _1, but resonant mode frequency f ₂ is derived by the diameter L _2. In the flat-shaped ultrasonic transducer 61 shown in the figure,
The L _2> L _1, and therefore, the frequency f ₁ based on the thickness L ₁
The resonance mode at, will be resonant frequency f ₂ is superimposed as harmonics (indicated by W), it can not be obtained a single resonant mode. Even if such an ultrasonic transducer 61 is broadened by the broadband matching electric circuit 64, a rectangular ultrasonic signal as shown in FIG. 3 cannot be obtained, and a high-resolution measuring device cannot be realized. SUMMARY An advantage of some aspects of the invention is to provide a measurement device that achieves high resolution by applying a broadband ultrasonic transducer having a novel configuration.

[0010]

According to the high-resolution measuring apparatus of the present invention, a large number of through holes are formed in the sound insulating material in the same direction in advance, and the dimensions of the ultrasonic radiation surface are formed in those through holes. An ultrasonic transducer formed by inserting a columnar ultrasonic transducer piece shorter than the height, a broadband matching unit connected to widen the ultrasonic transducer, and a short pulse ultrasonic signal during transmission. A short-pulse transmitter that supplies the ultrasonic transducer, a broadband receiver that amplifies a signal received by the ultrasonic transducer and processes the signal into a predetermined signal, and performs exploration based on the signal processed by the receiver. And a display unit for displaying the result as an image.

[0011]

According to the above construction, the ultrasonic vibrator composed of a plurality of columnar ultrasonic vibrator pieces whose ultrasonic radiation surface dimension is shorter than the height, vibrates in a single resonance mode as described later in detail. Therefore, by connecting this ultrasonic transducer to the broadband matching section, the ultrasonic transducer has ideal broadband characteristics. Accordingly, since a short pulse can be transmitted from the ultrasonic transducer, high-resolution measurement can be performed.

[0012]

FIG. 10 is a control block diagram showing one embodiment of the apparatus of the present invention. Reference numeral 1 denotes an ultrasonic transducer having a single resonance mode, the details of which will be described later. Reference numeral 2 denotes a broadband matching unit for increasing the bandwidth of the ultrasonic transducer 1 having a narrow band characteristic. Reference numeral 3 denotes a transmission / reception switching unit for switching between transmission and reception. Reference numeral 4 denotes a short pulse transmitting unit that outputs an ultrasonic signal in a short period as shown in FIG. Reference numeral 5 denotes a broadband receiving unit for amplifying the reception signal supplied from the transmission / reception switching unit 3, which is used in a wide band so as to process reception in a wide band. Reference numeral 6 denotes a control unit for centrally controlling the apparatus, and reference numeral 7 denotes a display unit for displaying an underwater search result.

Next, a specific configuration of the ultrasonic resonator 1 in the single resonance mode will be described. FIG. 11 shows a plan view thereof. 10 is a sound insulating material having a flat disk shape,
The sound insulating material 10 has a plurality of through holes 10a concentrically.
Are formed. In these through holes 10a, FIG.
Diameter height L ₁ as shown in the L ₂ (<L ₁₎ of a cylindrical ultrasonic transducer 11 is inserted. Accordingly, the diameter of the through hole 10a is substantially L _2, the thickness of the sound insulation material 10 becomes L _1.

FIG. 9 shows impedance characteristics when the columnar ultrasonic transducer 11 is excited by itself. The resonance points f ₁ and f ₂ (> f ₁ ) are equal to the height L ₁ of the columnar ultrasonic transducer 11.
And is based on the diameter L _2, in the vibrator 11, the height L ₁ using the resonance mode at the frequency f ₁ based on, but the frequency f ₂ of the resonant mode based on the size L ₂ is the frequency f ₁ for higher than, the resonant mode at the frequency f _1,
Never frequency f ₂ is superimposed, thus the columnar ultrasonic transducer 11 operates in a single resonant mode.

Unwanted ultrasonic waves radiated from the side are:
Since the sound is shielded by the sound insulating material 10, the ultrasonic wave emitted in the column direction does not interfere. Therefore, when a plurality of columnar ultrasonic transducers 11 are simultaneously driven, they operate in a single resonance mode and function as a single ultrasonic transducer.

However, in this state, there is a possibility that the columnar ultrasonic vibrator 11 may fall off from the sound insulating material 10. Therefore, it is necessary to provide some means for preventing falling off. Through hole 10a
The diameter and the smaller than L ₂ a method of fixing by press-fitting the columnar ultrasonic vibrator 11 into the through hole 10a is considered, case, As you sequentially press-fitting the columnar ultrasonic transducer 11, which As a result, the diameter of the through-hole 10a into which the columnar ultrasonic transducer 11 has not yet been inserted is reduced, and the insertion of the columnar ultrasonic transducer 11 becomes difficult,
Also, the elasticity of the sound insulating material is lost. Although there is a method of fixing with an adhesive, it is difficult to adhere to an elastic body.

Therefore, the present invention employs the following method. Diameter of the through hole 10a is leave substantially L _2, through-holes 1
After the discard hole 12 is provided around the hole 0a and the columnar ultrasonic transducer 11 is inserted into the through hole 10a, the discard hole 12
The pin-shaped ultrasonic transducer 11 is fixed at the position by press-fitting the pin 13 to the column-shaped ultrasonic transducer 11 and pressing the column-shaped ultrasonic transducer 11 with the surrounding sound insulating material 10. According to this method, the columnar ultrasonic vibrator 11 can be securely fixed to the sound insulating material 10, and the columnar ultrasonic vibrator 11 can be easily removed by removing the pin 13.

As shown in FIG. 12, each columnar ultrasonic vibrator 1
In 1, electrodes are formed on both end surfaces in the column direction, and lead wires Y from these electrodes are connected. By connecting a lead wire Y ₂ from the back electrode to the lower end of the pin 13 in the vicinity, a back surface is formed. lead Y ₂ of the electrode, as indicated by Y ₂ 'in FIG. 11, it is convenient could be drawn from the upper end of the pin 13. The plurality of columnar ultrasonic transducers 11 are connected to each other in parallel and connected to the broadband matching unit 2. Regarding the theory and the design values of L and C that allow the ultrasonic transducer to have a wide band by the broadband matching unit 2 composed of the elements L and C,
"Wideband matching of ultrasonic transducers" presented by Masao Kimura in the "Transactions of the Acoustical Society of Japan" in March 1983, and "An alg" by LJAugustine and J. Andersen.
orithm fordesign of transformerless broadband equa
lizers of ultrasonic transducers '' (September 1979, Aco
It is introduced in Volume 66 (No. 3) of the Ustical Society of America, and its description is omitted here.

Although not shown, the single-resonance-mode ultrasonic vibrator 1 configured as described above is provided with a backing layer on the back surface and coated with a molding material for protection. Therefore, by applying a conductive paint to the backing layer, a common back electrode for each columnar ultrasonic transducer 11 can be obtained.

Next, the operation of the apparatus having the above configuration will be described. The short pulse output from the short pulse transmitting unit 4 is applied to the ultrasonic transducer 1 in the single resonance mode via the transmission / reception switching unit 3 and the wideband matching unit 2. The vibrator 1 functions as a broadband element by adding the broadband matching unit 2, so that the ultrasonic vibrator 1 emits a wideband ultrasonic wave that changes into a pulse as shown in FIG. Is done. The echo accompanying the transmission is received by the ultrasonic vibrator 1 and passes through the broadband matching unit 2 to output a wideband received signal. This signal is amplified by the broadband receiving unit 5 via the transmission / reception switching unit 3, and under the control of the control unit 6, a high-resolution underwater exploration image as shown in FIG.

As described above, according to the present invention, a large number of through-holes are formed in the sound insulating material in the same direction in advance, and the diameter of the ultrasonic radiation surface is smaller than the height in these through-holes. Ultrasonic transducers with ultrasonic transducer pieces inserted are used in the measuring device, and the broadband is matched by the wideband matching section, so that ideal broadband characteristics can be obtained, and the transmission of pulsed ultrasonic waves can be achieved. The high resolution enables high-resolution measurement.

[Brief description of the drawings]

Fig. 1 Underwater exploration image measured by an ideal high-resolution fish finder

Fig. 2 Underwater exploration image measured by a conventional fish finder

FIG. 3 is a waveform diagram of an ultrasonic wave necessary for high-resolution measurement.

FIG. 4 is a diagram of an electric signal applied to an ultrasonic transducer to emit the ultrasonic wave of FIG. 3;

FIG. 5 is a waveform diagram of an ultrasonic wave emitted from a conventional narrow-band ultrasonic transducer when the electric signal of FIG. 4 is applied.

FIG. 6 is a diagram illustrating a technique for broadening the bandwidth of an ultrasonic transducer.

FIG. 7 is a diagram illustrating a technique for broadening the bandwidth of an ultrasonic transducer.

FIG. 8 is a diagram showing impedance characteristics of the ultrasonic transducer in the circuit configuration of FIG. 7;

FIG. 9 is a diagram showing impedance characteristics of a single-mode ultrasonic transducer used in the apparatus of the present invention.

FIG. 10 is a control block diagram showing one embodiment of the apparatus of the present invention.

FIG. 11 is a diagram showing a configuration of a broadband ultrasonic transducer used in the apparatus of the present invention.

FIG. 12 is a perspective view showing a columnar ultrasonic transducer in FIG. 11;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultrasonic transducer of single resonance mode 2 Broadband matching part 3 Transmission / reception switching part 4 Short pulse transmission part 5 Broadband receiving part 6 Control part 7 Display part 10 Sound insulation material 11 Columnar ultrasonic transducer 12 Discard hole 13 Pin

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shinji Ogawa 9-52 Ashihara-cho, Nishinomiya-shi, Hyogo Furuno Electric Co., Ltd. (56) References JP-A-56-116392 (JP, A) JP-A-1- 168198 (JP, A) Jiko 46-35667 (JP, Y1)

Claims (7)

(57) [Claims] 1. A plurality of through-holes, each having the same direction, are formed in advance in a sound insulating material, and a columnar ultrasonic vibrator piece having a dimension of an ultrasonic radiation surface shorter than a height is inserted into these through-holes. An ultrasonic vibrator, a broadband matching unit connected to widen the ultrasonic vibrator, and a short pulse transmitting unit that supplies a short pulse ultrasonic signal to the ultrasonic vibrator during transmission. A broadband receiving section that amplifies a signal received by the ultrasonic transducer and processes the signal into a predetermined signal; anda display section that displays a search result as an image based on the signal processed by the receiving section. Characteristic high-resolution measuring device. 2. A plurality of through-holes, each having the same direction, are formed in advance in the sound insulating material, and a columnar ultrasonic vibrator piece having a dimension of an ultrasonic radiation surface shorter than the height is inserted into these through-holes. A wide-band ultrasonic vibrator characterized in that the ultrasonic vibrator and the ultrasonic vibrator pieces are connected in parallel to each other and connected to a broadband matching section composed of L and C. 3. The wide-band ultrasonic vibrator according to claim 2, wherein the ultrasonic vibrator piece embedded in the sound insulating material is fixed by press-fitting a wedge-shaped pin into the sound insulating material. 4. A wide-band ultrasonic transducer according to claim 3, wherein a lead wire from a back electrode of said ultrasonic transducer piece is connected to a rear end of said pin, and said lead wire is drawn out from an upper end of said pin. . 5. A common back electrode for said plurality of ultrasonic vibrator pieces, wherein a conductive member is formed on a backing layer bonded to the back surface of said ultrasonic vibrator.
2. The wideband ultrasonic transducer according to claim 1. 6. An ultrasonic vibrator in which a plurality of columnar ultrasonic vibrator pieces each having a dimension of an ultrasonic wave radiating surface shorter than the height are arranged on one plane, and for widening the ultrasonic vibrator. A broadband matching unit to be connected; a short-pulse transmitting unit that supplies a short-pulse ultrasonic signal to the ultrasonic vibrator when transmitting; amplifies a signal received by the ultrasonic vibrator and processes the signal into a predetermined signal A high-resolution measurement device, comprising: a wide-band receiving unit that performs a search; and a display unit that displays a search result as an image based on a signal processed by the receiving unit. 7. A broadband ultrasonic vibrator usable for the high-resolution measuring device according to claim 6, wherein a plurality of columnar ultrasonic vibrator pieces whose ultrasonic radiation surface dimensions are shorter than the height are provided on the sound insulating material. Embedded, the ultrasonic transducer pieces are connected in parallel, and L,
A wide-band ultrasonic transducer connected to a wide-band matching section made of C.