JP2008026150A - Measured noise suppression method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measured noise suppression method for electronic devices capable of simply and inexpensively suppressing measured noise of an electronic device, and capable of being applied to an existing measuring apparatus. <P>SOLUTION: When measurement is performed by an electromagnetic ultrasonic method by using a measuring apparatus 1 having at least an electromagnetic ultrasonic probe 2, a pulser/receiver 7 for receiving a signal from the ultrasonic probe 2, and a cable 3 for transmitting the signal from the ultrasonic probe 2 to the pulser/receiver 7, a measuring object 4 and at least an external conductor 3c near the ultrasonic probe 2 of the cable 3 are electrically connected. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a measurement noise suppression method. More specifically, the present invention relates to a measurement noise suppression method suitable for use in an apparatus that measures the thickness of an object to be measured by an electromagnetic ultrasonic method using an electromagnetic ultrasonic probe.

  As a conventional technique for suppressing noise of a signal from a sensor or a probe received by a receiver of a measuring device when performing measurement using an electronic device, for example, an electromagnetic wave interference (hereinafter referred to as EMI) suppression cable (Patent Document 1). As shown in FIG. 6, the EMI suppression cable 101 includes a core wire bundle 102 with an insulating coating layer, and a shield layer 103 that is either a metal braided wire layer, a metal tape layer, or a mesh metal wire mixed resin layer on the outer periphery thereof. The outer peripheral ferrite compound-mixed resin layer 104 and the outer peripheral sheath layer 105 are further provided.

JP 2004-206953 A

  However, in the EMI suppression cable 101 of Patent Document 1, in order to suppress EMI noise, it is necessary to cover with four layers including the insulation coating layer of the core wire, which makes the structure complicated and troublesome and increases the cost. Connected. Moreover, since it cannot be applied additionally to the existing measuring apparatus, it is necessary to replace the entire cable of the existing measuring apparatus, and furthermore, it cannot be applied when the cable cannot be replaced. For this reason, it is hard to say that versatility is high.

  The present invention addresses such problems, and an object of the present invention is to provide a measurement noise suppression method that can suppress measurement noise of an electronic device easily and at low cost, and that can be applied to an existing measurement apparatus.

  During measurement by the electromagnetic ultrasonic method, the present inventors electrically connected the outer conductor of the cable that transmits a signal from the electromagnetic ultrasonic probe and the measurement object, which causes measurement noise. It was found that it is effective for suppression. It was also found that the effect of suppressing measurement noise is greater as the position of the outer conductor that is electrically connected to the measurement object is closer to the electromagnetic ultrasonic probe.

  The measurement noise suppression method of the present invention is based on the above knowledge, and includes an electromagnetic ultrasonic probe, a pulsar / receiver that receives a signal from the electromagnetic ultrasonic probe, and a pulsar from the electromagnetic ultrasonic probe. / When measuring by the electromagnetic ultrasonic method using a measuring device having at least a cable for transmitting a signal to the receiver, at least the outer conductor near the electromagnetic ultrasonic probe and the measurement object are electrically connected to the cable. I try to connect them.

  Therefore, according to this measurement noise suppression method, the measurement noise is suppressed because the measurement object is electrically connected to the outer conductor of the cable that transmits the signal from the electromagnetic ultrasonic probe to the pulser / receiver. Is done.

  According to the measurement noise suppression method of the present invention, since the external conductor of the cable that transmits a signal from the electromagnetic ultrasonic probe to the pulsar / receiver is electrically connected to the measurement object, the measurement noise is reduced. Suppression is possible, and measurement accuracy can be improved. In addition, measurement noise can be suppressed simply by electrically connecting the outer conductor of the cable and the object to be measured, so that the configuration is very simple, cost-effective and versatile. high. Moreover, since it can be additionally applied to an existing measuring apparatus, the existing apparatus is not wasted and is economical and versatile.

  Hereinafter, the configuration of the present invention will be described in detail based on the best mode shown in the drawings.

  FIG. 1 to FIG. 3 show an example of an embodiment in which the measurement noise suppression method of the present invention is applied to an apparatus 1 that measures the thickness of a metal specimen 4 that is a measurement object by an electromagnetic ultrasonic method. In this measurement noise suppression method, when the measurement is performed by the electromagnetic ultrasonic method using the measuring apparatus 1, at least the external conductor 3 c in the vicinity of the electromagnetic ultrasonic probe 2 and the metal specimen 4 are electrically connected to the cable 3. It is to be connected.

  In the present embodiment, the measuring apparatus 1 includes an electromagnetic ultrasonic probe 2, a diplexer 5 connected to the electromagnetic ultrasonic probe 2 by a cable 3, a preamplifier 6 connected to the diplexer 5, and an electromagnetic ultrasonic wave. A signal from the probe 2 is received via the diplexer 5 and received via the diplexer 5 and the preamplifier 6; a oscilloscope 8 to which a signal received by the pulser / receiver 7 is input; The personal computer 9 is configured to control the receiver 7.

  An electromagnetic ultrasonic probe (also referred to as EMAT) 2 is a probe used in an electromagnetic ultrasonic method, and can transmit and receive ultrasonic waves to and from a conductor by electromagnetic action. Any probe that can be used is acceptable. As shown in FIG. 2A, the electromagnetic ultrasonic probe 2 of the present embodiment includes a coil 2a obtained by winding a coated copper wire having a diameter of 0.3 mm in a track shape 25 times, and a magnetic flux density of 1.39 to 1. .45T of a pair of permanent magnets 2b and an insulating resin 2c covering the whole of the coils 2a and the permanent magnets 2b.

  Since the electromagnetic ultrasonic method itself is a well-known technique, the details are omitted here. In this embodiment, an eddy current and an electromagnetic wave excited by applying a high-frequency current to the coil 2a of the electromagnetic ultrasonic probe 2 using the measuring apparatus 1 having the electromagnetic ultrasonic probe 2 and the principle of the electromagnetic ultrasonic method. The direct current magnetic field generated by the permanent magnet 2b of the ultrasonic probe 2 excites the Lorentz force to the free electrons in the metal specimen 4 which is the object to be measured and is a conductor, and generates ultrasonic waves. Ultrasonic waves are received in the reverse process of the sound wave generation process, and the thickness of the metal specimen 4 is measured.

  In the present embodiment, as shown in FIG. 3, the cable 3 is knitted with a central inner conductor 3a, an insulator 3b covering the inner conductor 3a, and a thin metal wire covering the insulator 3b. A coaxial cable composed of a net-like outer conductor 3c and an insulating cover 3d covering the outer conductor 3c is used.

  One end of the coated copper wire forming the coil 2 a of the electromagnetic ultrasonic probe 2 is electrically connected to the inner conductor 3 a of the cable 3, and the other end of the coated copper wire is connected to the outside of the cable 3. It is electrically connected to the conductor 3c.

  The diplexer 5 (manufactured by RITEC, RDX-6) has damping and frequency filter functions.

  The preamplifier 6 (manufactured by RITEC, PAT-0.05-20) amplifies the signal before being input to the pulsar / receiver 7 when the signal received by the electromagnetic ultrasonic probe 2 is weak.

  The pulser / receiver 7 (manufactured by RITEC, SNAP5000) cooperates with the electromagnetic ultrasonic probe 2 to generate ultrasonic waves on the metal test specimen 4, and the electromagnetic ultrasonic probe 2 is moved from the metal test specimen 4. Receive the received ultrasonic signal.

  The signal received by the pulser / receiver 7 is input to an oscilloscope 8 (Tektronix TDS5034B), and the received waveform of the electromagnetic ultrasonic probe 2 is observed by the oscilloscope 8.

  The personal computer 9 controls the pulser / receiver 7 to monitor and control the excitation and reception of ultrasonic waves.

  The method of electrically connecting the external conductor 3c of the cable 3 and the metal test body 4 as the measurement object is not particularly limited, and any method can be used as long as the external conductor 3c and the metal test body 4 are short-circuited. Such a method may be used. In the present embodiment, as shown in FIG. 2B, the outer surface of the resin 2c of the electromagnetic ultrasonic probe 2 is covered with the aluminum foil 2d and the aluminum foil 2d and the external conductor 3c of the cable 3 are electrically connected. Let When the measurement is performed while the electromagnetic ultrasonic probe 2 is in contact with the metal specimen 4, the aluminum foil 2d and the metal specimen 4 are brought into contact with each other to electrically connect the external conductor 3c and the metal specimen 4. Let For the surface 2f of the electromagnetic ultrasonic probe 2 to be brought into contact with the metal test piece 4, only the edge 2e of the contact surface 2f is covered with the aluminum foil 2d so that the metal test piece 4 and the aluminum foil 2d are brought into contact with each other. I have to.

  As another method for electrically connecting the outer conductor 3c of the cable 3 and the metal test body 4 as the measurement object, as shown in FIG. 4, the outer conductor 3c is located in the vicinity of the electromagnetic ultrasonic probe 2. You may make it contact the metal test body 4 with the conducting wire 10 electrically connected to. In this case, the position where the external conductor 3c and the conductive wire 10 are electrically connected is preferably closer to the electromagnetic ultrasonic probe 2. And in the case of this embodiment, if the position which makes the conducting wire 10 and the metal test body 4 contact is a location which can be electrically connected with the metal test body 4, it will be from the position which measures with the electromagnetic ultrasonic probe 2. You can be away. Therefore, for example, even if the part to be measured by the electromagnetic ultrasonic probe 2 is covered with an insulator, the metal specimen 4 and the conductor 10 are brought into contact with each other at a place where the surface is not covered with the insulator. Thus, the present invention can be applied. Further, the present invention can be applied by partially removing the insulator covering the surface of the metal test body 4 and bringing the metal test body 4 and the conductive wire 10 into contact at the location where the insulator is removed.

  In addition, although the above-mentioned form is an example of the suitable form of this invention, it is not limited to this, A various deformation | transformation implementation is possible in the range which does not deviate from the summary of this invention. For example, in this embodiment, a coaxial cable having a net-like outer conductor 3c knitted with a thin metal wire is used as the cable 3. However, the configuration of the cable 3 to which the present invention can be applied is not limited to this, and the outer conductor is not limited thereto. It can be applied to general cables having

  In the present embodiment, the electromagnetic ultrasonic probe 2 has an insulating resin 2c that covers the entire coil 2a and permanent magnet 2b, but the configuration of the electromagnetic ultrasonic probe 2 is the same. The insulating resin 2c is not necessarily limited.

  Moreover, in this embodiment, although the measuring apparatus 1 provided with the diplexer 5 and the preamplifier 6 is used, the structure of the measuring apparatus 1 which can apply this invention is not restricted to this, The electromagnetic ultrasonic probe 2, the pulsar / Receiver 7 and a measuring apparatus having at least a cable 3 for transmitting a signal from the electromagnetic ultrasonic probe 2 to the pulser / receiver 7 can be applied.

  An embodiment in which the measurement noise suppression method of the present invention is applied to the actual thickness measurement of a metal specimen will be described with reference to FIG.

  In this embodiment, a block test body made of aluminum having a width of 58 mm, a length of 100 mm, and a thickness of 20 mm is used as the metal test body 4, and the electromagnetic noise between the case where the measurement noise suppression method of the present invention is not applied and the case where it is applied. The received waveforms of the ultrasonic probe 2 were compared. The frequency of the voltage applied to the electromagnetic ultrasonic probe 2 was 5.40 MHz.

  FIG. 5 shows the result of comparison of received waveforms. In FIG. 5, black arrows r indicate bottom reflected waves of the metal specimen 4 appearing at regular intervals, and white arrows n indicate measurement noise. A waveform having a large amplitude that appears first on the left side of the figure is a transmission pulse.

  When the measurement noise suppression method of the present invention is not applied, the measurement noise suppression method of the present invention is difficult because the amplitude of the measurement noise is large and it is difficult to identify the bottom reflected wave (FIG. 5A). Was applied, the measurement noise was almost suppressed, and the bottom reflected wave could be easily and clearly identified (FIG. 5B). In addition, the signal-to-noise ratio (also referred to as the SN ratio) was greatly improved from 0.8 to 7.2. From this result, it was confirmed that measurement noise can be significantly suppressed by the present invention.

It is a whole measuring device lineblock diagram showing an example of an embodiment of a measurement noise control method of the present invention. It is the perspective view which saw through resin of the electromagnetic ultrasonic probe of this embodiment. (A) is a perspective view in a state where there is no aluminum foil covering the outer surface of the resin. (B) is a perspective view of a state in which there is an aluminum foil covering the outer surface of the resin. It is a partially cutaway perspective view showing the coaxial cable of the present embodiment. It is a perspective view which shows the structure of the electromagnetic ultrasonic probe in other embodiment, a cable, and conducting wire. It is a figure which shows the received waveform of the electromagnetic ultrasonic probe of an Example. (A) is a figure which shows a received waveform when not applying the measurement noise suppression method of this invention. (B) is a figure which shows a received waveform at the time of applying the measurement noise suppression method of this invention. It is a partially cutaway perspective view showing a conventional EMI suppression cable.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Measuring apparatus 2 Electromagnetic ultrasonic probe 3 Cable 4 Metal specimen 5 Diplexer 6 Preamplifier 7 Pulsar / receiver 8 Oscilloscope 9 Personal computer 10 Conductor

Claims (1)

A measurement having at least an electromagnetic ultrasonic probe, a pulser / receiver that receives a signal from the electromagnetic ultrasonic probe, and a cable that transmits the signal from the electromagnetic ultrasonic probe to the pulser / receiver. A measurement noise suppressing method characterized by electrically connecting at least an outer conductor in the vicinity of the electromagnetic ultrasonic probe of the cable and a measurement object when performing measurement by an electromagnetic ultrasonic method using an apparatus. .

Images