JPS62133899A - Ultrasonic sensor - Google Patents

Abstract

PURPOSE:To prevent the sticking of a foreign substance such as solder, etc., and to improve durability and productivity by using a composite conductive member made by hardening tungsten powder with epoxy resin for back material that fixes and holds a resonator and burying the lead wire of an electrode of the vibrator in the back material. CONSTITUTION:The main body case 10 of an ultrasonic sensor is made cylindrical and a connector 12 is attached to it, and at the same time, plural annular grooves for anti-slipping 10A are formed on the outer peripheral face. A metallic supporting member 13 is fixed at the inside of a case 10 and a disk plate 14, an ultrasonic resonator 15 and a back material 16 are arranged from the bottom to upward and fixed on the inside of the member 13. A composite conductive member made by coating epoxy resin diluted with acetone on tungsten powder and kneading proper quantity of inorganic powder is used for the back material 16. A lead wire 15A for the electrode of the resonator 15 is laid in the back material 16. Thus, the sticking of foreign substance such as solder, etc., and the peeling off of the lead wire 15A is prevented and the durability and the productivity are improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ultrasonic sensor, and particularly relates to an ultrasonic sensor equipped with a backing material (vibrator holder) for firmly holding an ultrasonic transducer. .

[Conventional technology]

Ultrasonic probes are used as ultrasonic sensors used in ultrasonic flaw detection, etc., and are connected to ultrasonic flaw detectors.
Most of them employ a structure in which a vibrator is fixed to a backing material and housed in a predetermined case, with the intention of improving resolution when detecting internal defects in a member to be inspected.

The backing material generally has the property of allowing the vibrator to freely excite when it is excited, and suppressing the free vibration of the vibrator when it is not excited, and suppressing the transmission level that propagates from the vibrator. It is necessary to have properties that allow efficient absorption and attenuation of sound waves. In other words, these properties required for this backing material are as follows: (a) the acoustic impedance has a value close to the acoustic impedance of the ultrasonic transducer, thereby achieving acoustic matching with the ultrasonic transducer; (b) It must be a member that has high absorption and attenuation of ultrasonic waves;
It can be summarized in two points.

On the other hand, it is difficult to find a member in nature that satisfies all of these properties, and for this reason, materials such as tungsten powder solidified with epoxy resin are relatively often used these days.

[Problem that the invention seeks to solve]

However, in such a conventional example, the lead wire for applying a signal voltage to the vibrator is drawn out by cutting out a part of the backing material l, for example, as shown in FIG. Therefore, the processing and assembly is troublesome, and the lead wire 2A must be attached with solder or the like to the electrode surface that is attached to one side of the vibrator 2. Therefore, a part of the vibrator 2 is As a result, the vibration state of the vibrator 2 becomes partially irregular due to foreign matter that obstructs the vibration state, and over time, the vibration causes the solder 2
Problems such as B detaching from the electrode surface occurred.

[Purpose of the invention]

It is an object of the present invention to provide an ultrasonic sensor that improves the disadvantages of the conventional example, particularly eliminates the irregular vibration state of the vibrator, significantly improves durability, and at the same time improves productivity. , its purpose.

[Means for solving problems]

Therefore, in the present invention, in an ultrasonic sensor including an ultrasonic transducer and a backing material that firmly holds the ultrasonic transducer,
The backing material is constituted by a composite conductive member made of tungsten powder solidified with epoxy resin, and a lead wire for one electrode of the ultrasonic vibrator is embedded in the backing material, This aims to achieve the above objective.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which the present invention is applied to a probe for ultrasonic flaw detection will be described below with reference to FIGS. 1 and 2.

In these figures, 10 indicates a main body case, and 12 indicates a connector. In this embodiment, the main body case 10 has a cylindrical shape with a slightly thicker bottom, and a plurality of annular grooves 10A for preventing slippage are formed on the outer peripheral surface.

A cylindrical metal support member 13 is fixed within the main body case 10 and protrudes somewhat downward in the figure. Inside this cylindrical support member 13, a disk plate 14. A vibrator 15 and a backing material 16 are sequentially arranged and fixed.

In this case, the vibrator 15 is fixed to the lower end surface of the back material 16 in the same figure, and at the same time, the vibrator 15 is attached to the back surface in a cylindrical holder 18 made of an insulating material disposed inside the cylindrical support member 13. It is stored and fixed together with the material 16. and,
The disk plate 14 made of a conductive member is fixed to protect the cylindrical holder 18 and the lower end surface of the vibrator 15 in FIG.

In addition, the vibrator 15 has a disc shape in this embodiment, and has an acoustic impedance (ρc) of approximately 21×lO” (kg/I
′! ?・sec] lead niobate type (PbNbzOa)
In particular, some devices are used without a thin electrode film attached to either surface.

On the other hand, the backing material 16 suppresses the free vibration of the vibrator 15 when not excited as described above, and also absorbs and attenuates the ultrasonic waves propagating to the backing material 16 side during excitation, so that the backing material 16 attenuates the ultrasonic waves. A transducer having a large value and an acoustic impedance (ρC) close to that of the vibrator 15 is selected. The backing material 16 in this embodiment is made of a composite conductive material made by coating tungsten powder with an epoxy resin diluted with acetone and mixing it with an appropriate amount of inorganic powder. The material that is processed and molded into a predetermined shape is used.

Here, as the tungsten powder, in this example, one with an average particle size of 5 μm is mainly used, and a small amount of tungsten powder with an average particle size of around 1 μm or less is added to this, thereby making the tungsten powder The mutual adhesion is improved, and the electrical conductivity of the backing material 16 is set to be extremely high.

Further, 15A indicates a lead wire embedded in the backing material 16. This lead wire 15A is for applying a signal voltage for excitation of the vibrator to the vibrator 15 via the backing material 16, and specifically, a thin wire made of stranded silver wire or the like is used. Before the backing material 16 is solidified, it is buried as shown in the figure.

Therefore, the work of attaching the lead wire 15A does not require any skill and can be done very easily.
In this respect, the yield of work in attaching the lead wire 15A is significantly improved.

Furthermore, a filler 20 such as epoxy resin is filled above the backing material 16.

Further, 21 indicates a ground side lead wire, and 22 indicates a signal relay lead wire. The ground side lead wire 21 is a strip-shaped silver foil 2 fixed to one end of the disk plate 14.
4 and is connected to the ground side of the connector 12 via the main body case. Further, the signal relay lead wire 22 is connected to the signal transmission section 12B of the connector 12. Furthermore, a copper foil 2 for shielding is provided around the upper end of the inner surface of the main body case 10.
6 is installed. 27 indicates a metal lid.

When a predetermined signal voltage for excitation of the vibrator is input from the connector 12, this signal voltage is transmitted through the lead wire 15A and the backing material 16 in response to the earth electrode action of the disk plate 14. It is applied uniformly to the entire surface of one side of the vibrator 15. For this reason, the backing material 16
functions as an electrode surface on the signal application side of the vibrator 15,
As a result, the vibrator 15 is excited by the applied signal voltage and starts to vibrate effectively in synchronization with the applied signal voltage.

In this case, the vibrator 15 does not have solder for the lead wires as shown in the conventional example described above, and the signal voltage for excitation is uniformly applied to both sides of the vibrator as described above. Therefore, in this respect, the disadvantages of the conventional example are almost completely eliminated, and at the same time, the durability is significantly enhanced.

In addition, in the above-mentioned example, the case where the particle size of the tungsten powder is mainly used is 5 μm, but the present invention is not necessarily limited to this. Also, average particle size 1
Although a small amount of tungsten powder with a particle size of 1 μm is mixed in, the present invention is not necessarily limited to this. For example, tungsten powder with a different particle size of 1 μm or less or fine powder of other different materials may be mixed. It's okay to have one. Moreover, the inorganic powder is mixed in as needed, and does not need to be mixed in in particular.

Further, in the above embodiment, a case where one lead wire 15A is buried is illustrated, but a plurality of lead wires are buried with a predetermined gap and these multiple lead wires are buried on the upper surface side of the backing material 16 in FIG. may be grouped together and connected to the connector 12 via the signal relay lead wire 22 described above. In addition, although the buried end portion (lower end portion in FIG. 1) of the lead wire 15A has been illustrated only in the case where it is placed close to the vibrator 15, for example, the buried end portion of the lead wire 15A has a relatively Fine metal wires stretched at large intervals may be electrically conductive.

Further, in the above embodiment, a case where no adhesive is particularly used between the vibrator 15 and the backing material 16 is illustrated, but the present invention
The present invention is not necessarily limited to this, and the vibrator 15 may be bonded to the backing material 16 using a conductive adhesive, for example.

Furthermore, although the above embodiments are particularly exemplified with respect to a probe for ultrasonic flaw detection, the present invention is not necessarily limited to this, and can be applied as is to, for example, a medical ultrasonic diagnostic device or a fish finder. It is possible.

〔Effect of the invention〕

Since the present invention is configured and functions as described above, it is very easy to equip the lead wire for applying the excitation signal voltage to the vibrator, and no foreign matter such as solder is attached to the vibrator. Therefore, the vibration of the vibrator is accurately vibrated across the front surface, and there are no problems such as decreased sensitivity or inability to transmit/receive due to solder peeling accidents, and therefore durability and productivity are significantly improved compared to the conventional method. We can provide an excellent ultrasonic sensor that is not available in other countries.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG.
The front view of the figure and FIG. 3 are explanatory diagrams showing a conventional example. 15... Ultrasonic vibrator, 15A... Lead wire, 16... Back material. Patent applicant Tokyo Co., Ltd. Meter Figure 2

Claims (1)

[Claims] (1) In an ultrasonic sensor comprising an ultrasonic transducer and a backing material that firmly holds the ultrasonic transducer, the backing material:
An ultrasonic sensor comprising a composite conductive member made of tungsten powder hardened with an epoxy resin, and a lead wire for one electrode of the ultrasonic vibrator is embedded in the backing material.