JP2015179050A - Wall surface defect inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wall surface defect inspection device capable of correctly detecting wall surface defects by a simple inspection circuit, without requiring complex signal analysis.SOLUTION: The wall surface defect inspection device includes: an impact application unit for applying an impact (strike, friction, etc.) to a wall surface; a sound collecting microphone for collecting sounds generated by the impact given by the impact application unit; a first band-pass filter into which a microphone signal from the sound collecting microphone is input; a second band-pass filter into which the microphone signal is input and which has a different pass band from a pass band of the first band-pass filter; a first acoustic output unit for acoustically outputting the microphone signal that has passed through the first band-pass filter; and a second acoustic output unit for acoustically outputting the microphone signal that has passed through the second band-pass filter.

Description

  The present invention relates to a wall surface defect inspection apparatus capable of detecting a wall surface defect.

  The following conventional techniques are known for peeling and floating of wall coverings such as tiles, or for inspection of unhealthy parts of concrete.

  For example, in Patent Document 1, for the purpose of detecting an unhealthy part of concrete with very high accuracy, the frequency of the tapping sound generated by moving the polygonal head against the surface of the concrete structure while being moved is applied. An invention is described in which a change in the strength of the rolling sound with respect to the distribution of the above is analyzed, and a portion where the strength of the rolling sound is stronger than other portions is determined as an unhealthy portion. Thereby, it is said that the peak portion of the rolling sound can be easily found, and it can be easily determined that this portion is an all-in-one portion of the concrete structure.

  In addition, Patent Document 2 has a striking device capable of striking with a constant striking force for the purpose of quickly and accurately diagnosing the breakage of brick lining, and a microphone with a hood is placed near the striking location. This is a sound-inspecting method that performs analysis focusing on the frequency characteristics and amplitude characteristics of sound waves recorded on the wall surface as a result of being pressed against the wall and wavelet transformed. There has been disclosed a method for inspecting a brick lining joint sound, using the maximum intensity and the maximum peak frequency of the impact sound obtained from the wall surface of the brick as an index for evaluating the degree of joint breakage in the brick lining.

JP2013-253947A JP2007-240395

  In the prior art described above, the intensity of rolling sound and impact sound is analyzed in frequency distribution or the like to detect unhealthy portions of concrete and brick joint breaks. However, these conventional techniques require a complicated circuit for frequency analysis of tapping sound, striking sound, and the like, and an accurate detection result is not always obtained depending on the state of noise mixing. An object of the present invention is to provide a wall surface defect inspection apparatus that can detect a wall surface defect by a simple detection circuit without requiring complicated signal analysis or the like.

  In order to solve the above problems, in the first aspect of the present invention, an impact applying unit that applies an impact to a wall surface, a sound collecting microphone that collects sound generated by the impact applied by the impact applying unit, A first band pass filter to which a microphone signal from the sound collecting microphone is input; a second band pass filter to which the microphone signal is input and having a pass band different from the pass band of the first band pass filter; A wall defect inspection apparatus comprising: a first sound output unit that acoustically outputs a microphone signal that has passed through a first bandpass filter; and a second sound output unit that acoustically outputs a microphone signal that has passed through the second bandpass filter. provide.

  According to the wall surface defect inspection apparatus, the impact sound from the wall surface is generated from the sound from the first sound output unit that has passed through the first bandpass filter and from the second sound output unit that has passed through the second bandpass filter. Since it is output separately as a sound, it becomes easy to distinguish the presence or absence of a sound characteristic of a wall surface defect.

  The first sound output unit and the second sound output unit may be stereo headphones or stereo earphones, and one of the right channel or the left channel of the stereo headphones or the stereo earphones is the first sound output unit. The other can be the second sound output unit. As a result, both sounds can be compared and heard with both ears, and the presence or absence of a sound characteristic of the wall surface can be more easily distinguished.

  An example of the center wavelength of the pass band of the first band pass filter is 3 kHz, and an example of the center wavelength of the pass band of the second band pass filter is 5 kHz. The wall surface defect inspection apparatus may further include a noise microphone that collects ambient noise and a noise canceller that cancels noise included in the microphone signal using a noise signal from the noise microphone. Thereby, surrounding noise can be reduced and the presence or absence of the sound characteristic of the wall surface defect can be further easily identified.

2 is a functional block diagram showing a wall surface defect inspection apparatus 100. FIG. 3 is an appearance photograph showing an impact applying unit 102 and a sound collecting microphone 104 of the wall surface defect inspection apparatus 100. FIG. It is the graph which frequency-analyzed the microphone signal when there is no wall surface defect. It is the graph which analyzed the frequency after the microphone signal in case there is no wall surface defect passed the 1st band pass filter (center frequency 3kHz). It is the graph which analyzed the frequency after the microphone signal in case there is no wall surface defect passed the 2nd band pass filter (center frequency 5kHz). It is the graph which frequency-analyzed the microphone signal when there exists a wall surface defect. It is the graph which analyzed the frequency after the microphone signal in case there exists a wall surface defect passes a 1st band pass filter (center frequency 3kHz). It is the graph which analyzed the frequency after the microphone signal in case there exists a wall surface defect passes a 2nd band pass filter (center frequency 5kHz).

  FIG. 1 is a functional block diagram showing a wall surface defect inspection apparatus 100. The wall surface defect inspection apparatus 100 includes an impact applying unit 102, a sound collecting microphone 104, an amplifier 106, a first band pass filter 108, a second band pass filter 110, a first sound output unit 112, and a second sound output unit 114.

  The impact applying unit 102 applies impacts such as striking and friction to the wall surface 120 that is an object to be inspected, and the sound collecting microphone 104 collects sound from the wall surface 120 generated by the impact applied by the impact applying unit 102. . The amplifier 106 amplifies the output signal of the sound collecting microphone 104, and the amplified output signal of the sound collecting microphone 104 (hereinafter referred to as “microphone signal”) is sent to the first band pass filter 108 and the second band pass filter 110. Entered. The first acoustic output unit 112 acoustically outputs the microphone signal that has passed through the first bandpass filter 108, and the second acoustic output unit 114 acoustically outputs the microphone signal that has passed through the second bandpass filter 110. Note that when the output signal of the sound collection microphone 104 has a sufficient output level, signal amplification by the amplifier 106 is not necessary. That is, the amplifier 106 is not essential.

  The pass band of the first band pass filter 108 and the pass band of the second band pass filter 110 are different. For example, the center frequency of the pass band of the first band pass filter 108 can be 3 kHz, and the center frequency of the pass band of the second band pass filter 110 can be 5 kHz. The first sound output unit 112 and the second sound output unit 114 may be stereo headphones or stereo earphones, and one of the right channel or the left channel of the stereo headphones or stereo earphones is the first sound output unit 112, and the other Can be used as the second sound output unit 114.

  According to the wall surface defect inspection apparatus 100 of the present embodiment, a defect existing on the wall surface 120 can be detected easily and inexpensively. That is, sound is generated from the wall surface 120 by applying an impact to the wall surface 120 by the impact applying unit 102. If a tile stuck to the wall surface 120 has a wall surface defect such as floating or peeling, the sound generated from the wall surface 120 includes a characteristic sound due to the wall surface defect. The presence or absence of a wall surface defect can be detected by recognizing the presence or absence of a characteristic sound caused by the wall surface defect. In the wall surface defect inspection apparatus 100, the microphone signal collected by the sound collecting microphone 104 is separately acoustically output through the first bandpass filter 108 and the second bandpass filter 110 having different passbands. The acoustic output from the unit 112, that is, the acoustic output of the microphone signal that has passed through the first bandpass filter 108, and the acoustic output from the second acoustic output unit 114, that is, the acoustic output of the microphone signal that has passed through the second bandpass filter 110. You can listen to the contrast. Therefore, the characteristic sound resulting from the wall surface defect can be recognized and the wall surface defect can be easily detected.

  The wall surface defect inspection apparatus 100 according to the present embodiment does not include a complicated electronic circuit such as a frequency analysis circuit for extracting characteristic sounds due to wall surface defects. The wall surface defect inspection apparatus 100 includes only the first band-pass filter 108 and the second band-pass filter 110, which are very general electronic circuits, and thereby attempts to make the characteristic sound stand out. Therefore, the wall surface defect inspection apparatus 100 can be configured at low cost.

  When the center frequency of the pass band of the first band pass filter 108 is 3 kHz and the center frequency of the pass band of the second band pass filter 110 is 5 kHz, the characteristic sound (sound that can be heard steadily) due to the peeling of the wall tile is as follows: It tends to sound like. The sound output of the microphone signal that has passed through the first bandpass filter 108 (3 kHz) has a lot of ambient noise (noise), although the characteristic sound caused by the peeling of the wall tiles is emphasized and tends to be easily determined. Tend to include. On the other hand, the sound output of the microphone signal that has passed through the second bandpass filter 110 (5 kHz) is reduced in the surrounding noise and emphasizes the characteristic sound caused by the peeling of the wall tile, but the tile joint that occurs even in the normal part It tends to be difficult to distinguish the sound from the sound. Therefore, by comparing the two sound outputs in comparison, it becomes easy to distinguish and distinguish the characteristic sound resulting from the peeling of the wall tiles from the normal sound caused by the influence of the surrounding noise and the tile joint.

  The first sound output unit 112 and the second sound output unit 114 are stereo headphones or stereo earphones, one of the right channel or the left channel of the stereo headphones or stereo earphones is the first sound output unit 112, and the other is the second sound output unit 114. In this case, since the sound outputs from the first sound output unit 112 and the second sound output unit 114 can be discriminated by comparing with the right ear and the left ear, respectively, the characteristic sound caused by the wall surface defect can be clearly understood. Can be distinguished.

  Note that the wall surface defects include cracks, cracks, chips, and the like of the wall surface as well as tile floating and peeling, and the sound generated by the impact includes characteristic sounds corresponding to the types of the wall surface defects. Therefore, it is possible to identify the type of wall surface defect by recognizing the characteristic sound.

  FIG. 2 is an appearance photograph showing the impact applying unit 102 and the sound collecting microphone 104. As shown in FIG. 2, the wall surface defect inspection apparatus 100 according to the present embodiment includes both a hitting percussion bar for hitting and a rubbing percussion bar for friction as the impact application unit 102. The characteristic sound resulting from the wall surface defect differs depending on the type of impact, and the type of impact with which the presence or absence of the characteristic sound can be determined more easily can be selected. It should be noted that the impact applying unit 102 (striking bar and rubbing bar) and the sound collecting microphone 104 shown in FIG. 2 can move in the horizontal direction along the rail. 2 can move up and down along the wall surface 120 including the rail. Thereby, the wall surface 120 can be scanned vertically and horizontally, and the entire wall surface 120 can be inspected.

  3 to 8 are graphs obtained by frequency analysis of the microphone signal. FIGS. 3 to 5 show a case where there is no wall surface, and FIGS. 6 to 8 show a case where there is a wall surface defect. 3 and 6 show a case where the band-pass filter is not passed, FIGS. 4 and 7 show a case where the first band-pass filter 108 (center frequency 3 kHz) passes, and FIGS. 5 and 8 show the second band-pass filter 110. The case where it passes (center frequency 5kHz) is shown.

  3 and FIG. 6, FIG. 4 and FIG. 7, FIG. 5 and FIG. 8, it can be seen that a peak of characteristic sound (indicated by a white arrow) due to a wall surface defect appears in the vicinity of 2 kHz. Further, it can be seen that a normal sound peak that appears due to tile joints also appears in the vicinity of 5 kHz even when there is no wall surface defect.

  6 to 8, 1.5 kHz or less is obtained when the first band pass filter 108 (center frequency 3 kHz) is passed (FIG. 7) than when the band pass filter is not passed (FIG. 6). It can be seen that the level of the characteristic sound with respect to the ambient noise becomes higher, and further, when the second band pass filter 110 (center frequency 5 kHz) is passed (FIG. 8), the level of the characteristic sound with respect to the ambient noise becomes higher. On the other hand, in the case of FIG. 8, the level of normal sound having a peak in the vicinity of 5 kHz becomes high, and there is a possibility that it may be an obstacle to distinguish it from characteristic sounds due to wall surface defects. Considering the characteristics of the sound that has passed through each bandpass filter as described above, it becomes easy to distinguish the characteristic sound caused by the wall surface defect.

  The wall surface defect inspection apparatus 100 according to the present embodiment further includes a noise microphone that collects ambient noise, and a noise canceller that cancels noise included in the microphone signal using a noise signal from the noise microphone. May be. In this case, the level of ambient noise appearing at 1.5 kHz or lower can be reduced, and the distinction of characteristic sounds due to wall surface defects can be made easier. An example of the configuration of the noise canceller is a configuration in which an inverted signal obtained by inverting the signal from the noise microphone is generated, and appropriate level adjustment and phase adjustment are performed on the inverted signal and then superimposed on the microphone signal. In addition, a known noise canceller configuration can be applied.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  DESCRIPTION OF SYMBOLS 100 ... Wall surface defect inspection apparatus, 102 ... Impact application part, 104 ... Sound collection microphone, 106 ... Amplifier, 108 ... 1st band pass filter, 110 ... 2nd band pass filter, 112 ... 1st sound output part, 114 ... 1st 2 sound output units, 120.

Claims (4)

An impact applying unit for impacting the wall surface;
A sound collecting microphone for collecting sound generated by the shock given by the shock applying unit;
A first band pass filter to which a microphone signal from the sound collecting microphone is input;
A second bandpass filter having the passband different from the passband of the first bandpass filter, to which the microphone signal is input;
A first acoustic output unit that acoustically outputs a microphone signal that has passed through the first bandpass filter;
A second acoustic output unit that acoustically outputs a microphone signal that has passed through the second bandpass filter;
Wall surface defect inspection apparatus having The first sound output unit and the second sound output unit are stereo headphones or stereo earphones, one of the right channel or the left channel of the stereo headphones or the stereo earphones is the first sound output unit, and the other is the The wall surface defect inspection device according to claim 1, which is a second sound output unit. The wall surface defect inspection device according to claim 1, wherein a center wavelength of a pass band of the first band pass filter is 3 kHz, and a center wavelength of a pass band of the second band pass filter is 5 kHz. A noise microphone that collects ambient noise,
The wall defect inspection apparatus according to any one of claims 1 to 3, further comprising: a noise canceller that cancels noise included in the microphone signal using a noise signal from the noise microphone.