JP2007232577A - Flaw inspection method and flaw inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flaw inspection method capable of inspecting the wall surface or the like of a member to be inspected in a shorter time, and a flaw inspection device. <P>SOLUTION: A floodlight projection optical fiber and a light detecting optical fiber are used and the emitting surface of the floodlight projection optical fiber and the incident surface of the light detection optical fiber are arranged in opposed relationship so as to leave a definite distance while the member to be inspected, which permits the transmission of the detection light emitted from the floodlight projection optical fiber, is arranged between the emitting surface of the floodlight projection optical fiber and the incident surface of the light detection optical fiber, and the emitting surface of the floodlight projection optical fiber and the incident surface of the light detection optical fiber are relatively moved with respect to the member to be inspected along the surface of the member to be inspected. The flaw of the member to be inspected is judged on the basis of a change in the intensity of the detection light emitted from the emitting surface of the floodlight projection optical fiber and transmitted through the member to be inspected and thrown on the incident surface of the light detection optical fiber. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a defect inspection method and a defect inspection apparatus for detecting defects such as the surface of a member to be inspected (for example, inner peripheral wall surfaces such as cylinders, pipes, and machining holes).

Conventionally, when inspecting a cast hole or a processing flaw on the surface of an inner peripheral wall having a relatively large inner diameter such as a cylinder of a vehicle engine, an image processing apparatus is generally used by inserting a small CCD camera or the like. We are inspecting.
For example, in the prior art described in Patent Document 1, a cleaning unit that cleans residual liquid remaining on the inner surface of a cylindrical object to be inspected such as an engine cylinder, and an optical system that detects a two-dimensional image of the cleaned inner surface are detected. There has been proposed a defect inspection apparatus including an image processing unit that acquires defect information based on a two-dimensional image and an output unit that outputs the acquired defect information.
In the prior art described in Patent Document 2, an imaging means is inserted into the bore of the workpiece to be inspected to image the inner wall surface, image processing is performed to extract a feature parameter, and the extracted parameter value is compared with a reference value. There has been proposed a bore inner wall surface defect inspection apparatus that determines the presence or absence of a defect and sets the actual maximum dimension of the imaged defect candidate as a feature parameter.

In addition, examples of the apparatus for inspecting the inner peripheral wall surface as described above include a magnetic flaw detection apparatus using magnetic field lines, a laser light flaw detection apparatus using laser light, and the like.
For example, in the prior art described in Patent Document 3, a magnetic flaw detector composed of a magnetizer and a magnetic sensor, and a magnetic sensor placed close to a roll on which a metal strip (workpiece) travels, and the rotation of one roll is a period of the magnetic sensor. A metal band magnetic flaw detector that classifies output data obtained by converting a signal from a digital signal into signals and detects the presence or absence of a metal band defect from the difference data between the section data and the next period section data has been proposed. .
JP-A-2005-121450 JP-A-9-311107 JP-A-9-229906

In the conventional technique using the image processing described in Patent Document 1 and Patent Document 2, a CCD camera or a mirror is rotated inside a cylinder. However, illumination light is necessary for imaging, and the CCD camera (or mirror) Similarly, it is necessary to rotate the illumination in the cylinder, and the operation is difficult. Moreover, in order to detect a defect from a captured image, complicated image processing is required, and the time required for inspection is long, and a longer time is required when the detection accuracy is increased. Also, since the internal diameter of the engine cylinder is relatively large, a CCD camera and illumination can be inserted into the cylinder, but in the case of various valve cylinders, brake cylinders, fuel injection nozzles, etc. of the vehicle, the hole diameter is small. It is very difficult to insert the camera and imaging light into the cylinder.
Further, in the prior art using the magnetic flaw detection apparatus described in Patent Document 3, the magnetizer and the magnetic sensor are arranged on the inner wall side and the outer wall side of the cylinder to detect the change in magnetism, so that the engine whose cylinder thickness changes It is very difficult to detect defects with a cylinder or the like.
Further, in the conventional technique using a laser beam flaw detector, the diameter of a spot hit by a laser beam is very small, so that the time required for inspection becomes long.
The present invention has been made in view of such points, and it is an object of the present invention to provide a defect inspection method and a defect inspection apparatus capable of inspecting defects such as a wall surface of a member to be inspected in a shorter time. .

As means for solving the above-mentioned problems, the first invention of the present invention is a defect inspection method as described in claim 1.
In the defect inspection method according to claim 1, a light projecting optical fiber and a light receiving optical fiber are used.
A member to be inspected that is arranged so that the emission surface of the light projecting optical fiber and the light incident surface of the light receiving optical fiber face each other so as to maintain a certain distance, and transmits the detection light emitted from the light projecting optical fiber Is disposed between the exit surface of the light projecting optical fiber and the entrance surface of the light receiving optical fiber, and the exit surface of the light projecting optical fiber and the entrance surface of the light receiving optical fiber are arranged on the member to be inspected. The light is moved relative to the member to be inspected along the surface, is emitted from the emission surface of the light projecting optical fiber, passes through the member to be inspected, and is incident on the incident surface of the light receiving optical fiber. The defect of the member to be inspected is determined based on the change in the intensity of the detection light.

The second invention of the present invention is a defect inspection method as set forth in claim 2.
In the defect inspection method according to claim 2, a light projecting optical fiber and a light receiving optical fiber are used.
When inspecting a member to be inspected that reflects the detection light emitted from the light projecting optical fiber, the light emitting surface of the light projecting optical fiber arranged side by side so as to maintain a certain distance from the surface of the member to be inspected; The incident surface of the light receiving optical fiber is moved relative to the member to be inspected along the surface of the member to be inspected.
When inspecting a member to be inspected that transmits detection light emitted from the light projecting optical fiber, the light exiting surface of the light projecting optical fiber opposed to maintain a certain distance across the member to be inspected and the The incident surface of the light receiving optical fiber is moved relative to the member to be inspected along the surface of the member to be inspected.
A voltage conversion step for converting the detection light incident on the light receiving optical fiber into a voltage signal corresponding to the intensity of the detection light, and a voltage signal output from the voltage conversion step are set to a first reference set in advance. A feedback control step having a feedback unit that shifts to a voltage and removes a swell component of the voltage signal; and a voltage shift step that shifts a voltage signal output from the feedback control step to a preset second reference voltage; The voltage signal output from the voltage shift step amplifies a voltage signal whose peak value is greater than or equal to the external input voltage, and cuts or attenuates a voltage signal whose peak value is less than the external input voltage to generate a defective signal. A defect emphasizing step for obtaining an emphasized determination signal; and a signal having a peak value equal to or higher than a first predetermined voltage in the determination signal. Recessed and a determination step of determining a.
Furthermore, it has a smoothing step for smoothing the peak value of the voltage signal output from the voltage shift step, and uses the smoothed signal output from the smoothing step as the external input voltage for the defect emphasizing step. .

A third aspect of the present invention is a defect inspection method as set forth in the third aspect.
In the defect inspection method according to claim 3, a light projecting optical fiber and a light receiving optical fiber are used.
When inspecting a member to be inspected that reflects the detection light emitted from the light projecting optical fiber, the light emitting surface of the light projecting optical fiber arranged side by side so as to maintain a certain distance from the surface of the member to be inspected; The incident surface of the light receiving optical fiber is moved relative to the member to be inspected along the surface of the member to be inspected.
When inspecting a member to be inspected that transmits detection light emitted from the light projecting optical fiber, the light exiting surface of the light projecting optical fiber opposed to maintain a certain distance across the member to be inspected and the The incident surface of the light receiving optical fiber is moved relative to the member to be inspected along the surface of the member to be inspected.
Further, when the light receiving optical fiber is configured as a pair and is relatively moved along the surface, the light receiving optical fiber incident surface is followed by the light receiving optical fiber incident surface on the surface. Move to pass the same position.
Then, a first voltage conversion step for converting the first detection light incident on one light receiving fiber into a first voltage signal corresponding to the intensity of the first detection light, and a first voltage incident on the other light receiving fiber. A second voltage conversion step of converting the two detection lights into a second voltage signal corresponding to the intensity of the second detection light, and a difference for obtaining a difference signal indicating a difference between the first voltage signal and the second voltage signal And a smoothing step for obtaining a smoothed signal obtained by smoothing the peak value of the differential signal, and a signal that is equal to or higher than the peak value of the smoothed signal in the differential signal from the differential signal and the smoothed signal. In the defect emphasizing step for obtaining a determination signal in which the defect signal is emphasized by cutting or attenuating a signal that is less than the peak value of the smoothed signal in the difference signal, and the determination signal, Height value and a determination step of determining a defect a second predetermined voltage or more signals.

A fourth aspect of the present invention is a defect inspection apparatus as set forth in the fourth aspect.
A defect inspection apparatus according to a fourth aspect includes a light projecting optical fiber, a light receiving optical fiber, and a control device.
When inspecting a member to be inspected that reflects the detection light emitted from the light projecting optical fiber, the light emitting surface of the light projecting optical fiber arranged side by side so as to maintain a certain distance from the surface of the member to be inspected; The incident surface of the light receiving optical fiber is moved relative to the member to be inspected along the surface of the member to be inspected.
When inspecting a member to be inspected that transmits detection light emitted from the light projecting optical fiber, the light exiting surface of the light projecting optical fiber opposed to maintain a certain distance across the member to be inspected and the The incident surface of the light receiving optical fiber is moved relative to the member to be inspected along the surface of the member to be inspected.
When the detection light incident on the light receiving optical fiber is input, the control device outputs a voltage signal corresponding to the intensity of the input detection light, and is output from the voltage conversion unit. A feedback control means having a feedback section for shifting the voltage signal to the first reference voltage set in advance and removing the undulation component of the voltage signal, and a voltage signal output from the feedback control means is set in advance. In the voltage shift means for shifting to the second reference voltage and the voltage signal output from the voltage shift means, the voltage signal whose peak value is equal to or greater than the external input voltage is amplified, and the peak value is less than the external input voltage. Defect emphasis means for outputting a determination signal in which the defect signal is emphasized by cutting or attenuating the voltage signal, and when the determination signal is input, the input for determination Peak value and a determination means and defect a first predetermined voltage or more signals in No..
Furthermore, a smoothing means for smoothing the peak value of the voltage signal output from the voltage shift means is provided, and the smoothed signal output from the smoothing means is input to the defect emphasis means as the external input voltage. .

A fifth aspect of the present invention is a defect inspection apparatus as set forth in the fifth aspect.
A defect inspection apparatus according to a fifth aspect includes a light projecting optical fiber, a light receiving optical fiber, and a control device.
When inspecting a member to be inspected that reflects the detection light emitted from the light projecting optical fiber, the light emitting surface of the light projecting optical fiber arranged side by side so as to maintain a certain distance from the surface of the member to be inspected; The incident surface of the light receiving optical fiber is moved relative to the member to be inspected along the surface of the member to be inspected.
When inspecting a member to be inspected that transmits detection light emitted from the light projecting optical fiber, the light exiting surface of the light projecting optical fiber opposed to maintain a certain distance across the member to be inspected and the The incident surface of the light receiving optical fiber is moved relative to the member to be inspected along the surface of the member to be inspected.
The light receiving optical fiber is configured as a pair, and when the light receiving optical fiber is relatively moved along the surface, the light receiving optical fiber incident surface is followed by the light receiving optical fiber incident surface of the other light receiving optical fiber. Move to pass the same position above.
When the first detection light incident on one of the light receiving fibers is input, the control device outputs a first voltage signal corresponding to the intensity of the input first detection light; ,
When the second detection light incident on the other light receiving fiber is input, second voltage conversion means for outputting a second voltage signal corresponding to the intensity of the input second detection light; and the first voltage signal When the second voltage signal is input, differential operation means for outputting a difference signal indicating a difference between the input first voltage signal and the second voltage signal, and a peak value of the difference signal are smoothed Smoothing means for outputting a smoothed signal; and when the difference signal and the smoothed signal are input, a signal that is equal to or higher than a peak value of the smoothed signal in the difference signal is amplified, and the difference signal Defect emphasizing means for outputting a determination signal in which a defect signal is emphasized by cutting or attenuating a signal that is less than the peak value of the smoothing signal, and when the determination signal is input, in the input determination signal Crest value is second predetermined The signal on the pressure or comprises a determining unit and defects.

  When the defect inspection method according to claim 1 is used, a member having various shapes formed of a material that transmits detection light, such as a cylindrical member or a plate member formed of a material that transmits detection light, is inspected. Since a defect is detected as a member based on a change in the intensity of the detected light that is transmitted through the detection light, defects such as scratches can be easily determined on the surface and inside of the member to be inspected.

Further, when the defect inspection method according to claim 2 is used, when the detection light incident on the light receiving optical fiber is input, the input detection light is converted into a voltage signal in a voltage conversion step. The converted voltage signal has, for example, a swell component due to a difference in hue and gloss caused by heat treatment, chemical treatment, processing, etc., or a width of an output voltage level, depending on the position of the surface of the member to be inspected. . Further, it has a range of swell components and output voltage levels due to a change in the distance between the surface of the member to be inspected and the optical fiber, vibration, and the like.
Therefore, even if the output voltage level of the voltage signal is different for each inspection or the voltage signal is wobbling during the inspection, a flattened signal centered on the second reference voltage in the feedback control step and the voltage shift step. (See FIG. 6C), and further, the defect signal is appropriately emphasized in the smoothing signal obtained in the smoothing step and the defect emphasizing step, so that a fine scratch (not a defect) of the member to be inspected is obtained. ) Or the like, a defect signal component buried in a noise component (a signal component corresponding to a defect such as a cast hole or a processing flaw) can be appropriately extracted.
In addition, the defect inspection is performed in a shorter time because the light projecting optical fiber and the light receiving optical fiber are moved relative to the member to be inspected along the surface of the member to be inspected. It is possible.

When the defect inspection method according to claim 3 is used, a pair of light receiving optical fibers is configured, and the other light receiving optical fiber also passes through the position of the member to be inspected through which one light receiving optical fiber has passed. . Then, a difference signal is obtained from the difference between the first voltage signal corresponding to the intensity of the detection light from one light receiving optical fiber and the second voltage signal corresponding to the intensity of the detection light from the other light receiving optical fiber. Even if the same position is passed, it does not pass the same position at the same time. Therefore, the first voltage signal and the second voltage signal have substantially the same waveform and a slight time shift, and a defect signal is detected. Since a slight time lag has occurred at the position where it is located, when a difference is obtained, a swell component that changes in a relatively long time can be appropriately removed without losing a defect signal.
Then, the defect signal component (which is buried in the noise component due to fine scratches (not defects), etc., of the member to be inspected by appropriately enhancing the defect signal in the smoothing signal obtained in the smoothing step and the defect emphasizing step ( It is possible to appropriately extract a signal component corresponding to a defect such as a cast hole or a processing flaw.
In addition, the defect signal component buried in the noise component due to fine scratches (not defects) or the like of the member to be inspected by appropriately enhancing the defect signal in the smoothing signal obtained in the smoothing step and the defect emphasizing step ( The signal component corresponding to the defect such as a casting hole or a processing flaw) can be extracted more appropriately.

  Moreover, in the defect inspection apparatus of Claim 4 and 5, each defect inspection apparatus using each defect inspection method of Claim 2 and 3 can be implement | achieved easily.

The best mode for carrying out the present invention will be described below with reference to the drawings.
The defect inspection apparatus 1 according to the first embodiment described with reference to the examples of FIGS. 1 to 5 includes defects (casting) on various inner wall surfaces such as cylinders, pipes, and machining holes having wall surfaces made of a material that reflects detection light. The present invention can be applied to detection of nests, processing flaws, and the like, and will be described with reference to an example in which the present invention is applied to detection of defects on the inner wall surface of the cylinder S.
●● [First embodiment (FIGS. 1 to 5)]
● [Detection pipe structure (FIG. 1A) and overall structure of defect inspection apparatus 1 (FIG. 1B)]
FIG. 1 (A) shows an example of an external view of an embodiment of the detection pipe 10 in the first embodiment of the defect inspection apparatus 1 of the present invention, and FIG. 1 (B) is a defect of the present invention. The example of the whole structure in 1st Embodiment of the inspection apparatus 1 is shown.
In the first embodiment, the member S to be inspected is a material that reflects detection light.
As shown in FIG. 1A, the detection pipe 10 includes a detection unit 13, an insertion unit 11, a support unit 12, a flexible tube 14, an attachment unit 15, and the like.
In the detection unit 13, the emission surface of the light projecting optical fiber 13a and the incident surface of the light receiving optical fiber 13b are arranged in a predetermined direction (see FIGS. 2A and 3A). The detection unit 13 is provided at the distal end of the insertion unit 11, and the insertion unit 11 is inserted along the axial direction of a substantially cylindrical space to be inspected. The insertion section 11 accommodates a bundle of light projecting optical fibers 13a and light receiving optical fibers 13b. The bundle of light projecting optical fibers 13a and light receiving optical fibers 13b is externally connected by a flexible tube 14. Has been drawn to.

An attachment portion 15 (attachment screw or the like) is fixed to the support portion 12. As shown in FIG. 1B, the mounting portion 15 is fixed to the tool T, and the tool T moves the detection pipe 10 relatively reciprocally along the axis ZS of the cylinder S inside the cylinder S, or the cylinder S Is relatively rotated along the circumferential direction of the inner peripheral wall surface. Therefore, the detection pipe 10 may be moved, or the cylinder S may be moved.
The length LH in the longitudinal direction of the insertion portion 11 is set according to the length of the inner peripheral wall surface of the cylindrical space to be inspected, and the diameter φ of the insertion portion 11 is set to the inner peripheral wall surface of the cylindrical space to be inspected. It is set according to the diameter. The diameters of the projecting optical fiber 13a and the receiving optical fiber 13b are, for example, about 0.25 [mm] to 0.5 [mm]. The diameter φ of 11 is sufficiently within a few [mm]. Therefore, the insertion portion 11 can be inserted even with a hole having a relatively small diameter of about several mm, which is difficult to insert a CCD camera or the like.
The length LZ of the detection unit 13 in the Z-axis direction is set as appropriate.

As shown in FIG. 1B, the first embodiment of the defect inspection apparatus 1 according to the present invention includes a detection pipe 10 and a control apparatus 30. The control device 30 includes, for example, a personal computer 23 (hereinafter referred to as a personal computer 23), a signal processing unit 21, a driving unit 22, and the like.
The signal processing means 21 is connected to the detection pipe 10 and the flexible tube 14, and supplies light irradiated from the emission surface of the light projecting optical fiber 13 a of the detection unit 13 based on a control signal from the personal computer 23. The detection light incident on the incident surface of the light receiving optical fiber 13 b of the detection unit 13 is received, and the detected detection signal is transmitted to the personal computer 23. Then, the personal computer 23 counts defects and determines abnormality based on the detection signal input from the signal processing means 21 and outputs an alarm signal (sound, display, etc.).
The driving means 22 rotates or slides (reciprocates) the tool T based on a control signal from the personal computer 23. Note that the cylinder S may be rotated or slid.

● [The shape of the detection pipe 10 and the movement method on the inner wall surface (FIGS. 2 and 3)]
Next, the shape of the detection pipe 10 and the moving method on the inner peripheral wall surface will be described with reference to FIGS. 2 (A) to 2 (C) and FIGS. 3 (A) to 3 (C).
The insertion portion 11 of the detection pipe 10 accommodates a plurality of light receiving optical fibers 13b and a plurality of light projecting optical fibers 13a.

[First shape and moving method]
As shown in FIG. 2A, in [First shape and moving method], the incident surface of the light receiving optical fiber 13b arranged in the detection unit 13 is along a direction parallel to the axis ZS of the cylinder S. Arranged in rows. The incident surface of the light receiving optical fiber 13b is directed so as to face the inner peripheral wall surface of the cylindrical space, and the respective incident surfaces are directed in the same direction.
Further, the emission surface of the light projecting optical fiber 13a is arranged in parallel with the incident surface of the light receiving optical fiber 13b arranged in a row, and each light emitting surface is connected to the incident surface of the light receiving optical fiber 13b. They are oriented in the same direction. In the example shown in FIG. 2A, the incident surface of the light receiving optical fiber 13b has one row and the exit surface of the light projecting optical fiber 13a has two rows. However, the number is not limited to this number. Absent.

Next, a procedure for detecting a defect on the inner peripheral wall surface of the cylinder S will be described with reference to FIG.
When detecting a defect on the inner peripheral wall surface of the cylinder S, the insertion portion 11 is first inserted into the cylinder S along the axis ZS of the cylinder S. At the inserted position, a distance GA between each of the light exiting surfaces of the light projecting optical fiber 13a and each light incident surface of the light receiving optical fiber 13b and the inner peripheral wall surface of the opposing cylinder S is set to a predetermined distance (for example, 0.5). (Mm) to an appropriate value within the range of 3.5 [mm] (see FIG. 2B).

Further, the control device 30 relatively rotates the insertion portion 11 along the circumferential direction of the inner peripheral wall surface of the cylinder S so as to keep the distance GA constant by using the driving means 22 (see FIG. 2B). ). In addition, since the flexible tube 14 is pulled out from the insertion part 11, it is preferable to make the rotation direction alternate, for example, to make one rotation in the counterclockwise direction after making one rotation in the clockwise direction.
And the control apparatus 30 detects the defect of the inner peripheral wall surface of the cylinder S based on the detection light output from the output surface of the optical fiber 13b for light reception, rotating the insertion part 11 relatively.
For this reason, it is possible to detect the entire circumference of the cylinder inner peripheral wall surface only by rotating the detection unit 13 once along the circumferential direction of the cylinder inner peripheral wall surface. No stable automatic inspection is possible.
When the length of the cylinder inner peripheral wall surface in the longitudinal direction is longer than the length LZ of the detection unit 13, first, the detection unit 13 is rotated once to inspect the inner peripheral wall surface with the width of the detection unit 13 length LZ. This is repeated until the length of the inner circumferential wall surface of the cylinder reaches the length in the longitudinal direction.
Note that if a plurality of detection units 13 are provided as shown in the example of FIG. 2C, the inspection time can be further shortened (in the example of FIG. 2C, there is no need to rotate 360 °). , 180 ° rotation is sufficient).

[Second shape and moving method]
[Second shape and moving method] is different from [First shape and moving method] in the incident surface of the plurality of light receiving optical fibers 13b and the emitting surface of the plurality of light projecting optical fibers 13a in the detection unit 13. Are different from each other in the arrangement direction of the insertion portion 11 after the insertion portion 11 is inserted into the cylinder S. Hereinafter, differences from [First shape and moving method] will be described.

As shown in FIG. 3A, in [Second shape and moving method], the incident surface of the light receiving optical fiber 13b arranged in the detection unit 13 is along a direction perpendicular to the axis ZS of the cylinder S. Arranged in rows. The incident surface of the light receiving optical fiber 13b is directed so as to face the inner peripheral wall surface of the cylindrical space, and the respective incident surfaces are directed in the same direction.
Further, the emission surface of the light projecting optical fiber 13a is arranged in parallel with the incident surface of the light receiving optical fiber 13b arranged in a row, and each light emitting surface is connected to the incident surface of the light receiving optical fiber 13b. They are oriented in the same direction. In the example shown in FIG. 3A, the incident surface of the light receiving optical fiber 13b has one row and the exit surface of the light projecting optical fiber 13a has two rows. However, the number is not limited to this number. Absent.

Next, a procedure for detecting a defect on the inner peripheral wall surface of the cylinder S will be described with reference to FIG.
When detecting a defect on the inner peripheral wall surface of the cylinder S, the insertion portion 11 is first inserted into the cylinder S along the axis ZS of the cylinder S. At the inserted position, a distance GB between each of the emission surfaces of the light projecting optical fiber 13a and each of the incident surfaces of the light receiving optical fiber 13b and the inner peripheral wall surface of the opposing cylinder S is a predetermined distance (for example, 0.5 It is set to be an appropriate value within the range of [mm] to 3.5 [mm] (see FIG. 3B).
Further, the control device 30 relatively slides (reciprocates) the insertion portion 11 along the axial direction (the direction of the axis ZS) of the inner peripheral wall surface of the cylinder S so as to keep the distance GB constant by using the driving means 22. (See FIG. 3B).
And the control apparatus 30 detects the defect of the inner peripheral wall surface of the cylinder S based on the detection light output from the output surface of the optical fiber 13b for light reception, sliding the insertion part 11 relatively (reciprocating).
In [Second shape and movement method], an inspection is performed in which the cylinder is slid in the longitudinal direction of the cylinder with the detection width of LY (forward path), rotated to the undetected peripheral portion and slid in the longitudinal direction (return path). Repeat until the entire circumference of the wall is reached.
In this way, it is possible to greatly reduce the inspection time and perform stable automatic inspection without relying on visual observation.
If a plurality of detection units 13 are provided as shown in the example of FIG. 3C, the inspection time can be further shortened.

● [Schematic configuration of control device for determining defect and schematic waveform of detection signal (FIGS. 4 to 6)]
FIG. 4 shows a schematic configuration of the signal processing means 21 in the control device 30, FIG. 5 shows a detailed configuration, and FIG. 6 shows an example of waveforms (signals) of each part of FIG. The waveform example shown in FIG. 6 is a waveform measured by an oscilloscope, with the horizontal axis indicating time [S] and the vertical axis indicating voltage [V].
As shown in FIG. 4, the signal processing unit 21 in the control device 30 includes a light source 31, a voltage conversion unit 32, a feedback control unit 38, a voltage shift unit 39, a smoothing unit 34, a defect enhancement unit 36, and a determination unit 37. ing.
Further, the emission surface of the light projecting optical fiber 13a and the incident surface of the light receiving optical fiber 13b are arranged side by side so as to maintain a certain distance GA or GB from the surface (wall surface M) of the member S to be inspected.

The signal processing means 21 uses the light source 31 to make light incident on the incident surface of the light projecting optical fiber 13a. For example, an LED is used as the light source 31, and visible red light is incident on the incident surface of the light projecting optical fiber 13a.
When the wall surface M to be inspected has no defect, a part of the light that is emitted from the emission surface 13aout of the light projecting optical fiber 13a and reflected from the wall surface M, as indicated by the one-dot chain circle in FIG. Is incident on the incident surface 13bin of the light receiving optical fiber 13b, and the intensity of the light becomes substantially constant. However, when there is a defect (such as a casting hole or a processing flaw), irregular reflection occurs on the wall surface M of the defective portion, so that the intensity of light incident on the incident surface 13bin is reduced. A defect is detected by detecting the reduced light.

As shown in FIGS. 4 and 5, the detection light output from the emission surface of the light-receiving optical fiber 13b is input to the voltage conversion means 32, and the voltage conversion means 32 performs an electrical operation according to the intensity of the input detection light. A signal (voltage signal) is output (corresponding to a voltage conversion step, see FIG. 6A “Waveform of S1” for the waveform). In the example shown in FIG. 5, the detection light is converted into an electric signal by the photodiode D1, and further amplified by the amplifier 32a to obtain a voltage signal S1 (see “waveform of S1” in FIG. 6A). In this case, in the voltage signal S1, the portion where the intensity of the detection light is reduced becomes a defect signal, and thus a pulse slightly protruding to the negative side becomes the defect signal.
Note that the converted voltage signal S1 has various swell components (FIG. 6A) due to differences in hue and gloss caused by heat treatment, chemical treatment, processing, etc., depending on the position of the wall surface M to be inspected. It has ΔV in “S1 waveform”) and various output voltage levels (see V1 in “S1 waveform” in FIG. 6A).
Further, when the distance M or GB between the emission surface 13aout of the light projecting optical fiber 13a and the incident surface 13bin of the light receiving optical fiber 13b and the wall surface M is rotated or reciprocated so as to be kept constant, It also has a swell component or output voltage level width caused by a change in the distance GA or GB, vibration, or the like.

The voltage signal S1 output from the voltage conversion unit 32 is input to the feedback control unit 38.
The feedback control means 38 includes, for example, an amplifier 38a, a low-pass filter 38b, a feedback amount adjuster 38c, and an amplification factor setting unit 38d.
As shown in FIG. 5, the voltage signal S1 is input to the amplifier 38a, and the signal output from the amplifier 38a is supplied to the low-pass filter 38b and the feedback amount adjuster 38c (the amount of feedback can be adjusted by the amplification factor setting unit 38d). Feedback.
Here, the detection light (reflected light) is affected by fluctuations in the optical properties such as the hue and gloss of the inner wall surface M due to differences in the production lot, composition, heat, chemical treatment, processing, etc. of the inspection object, and vibrations in the inspection. Intensity may vary. This variation is generally gentle and relatively large on a large time scale. For this reason, the normal surface level signal S2a (the output of the low-pass filter 38b, see FIG. 5) corresponding to the normal surface that fluctuates greatly is taken out with the defect signal stored by the low-pass filter 38b. A feedback amount for comparing and amplifying the reference voltage S2c (which is a reference amplification factor, which corresponds to the reference voltage LV in “S2 waveform” in FIG. 6) and the signal S2a, which can be set by the external gain setting device 38d. The signal S2b output from the adjuster 38c is fed back to the amplifier 38a and controlled so as to become the reference voltage S2c (reference voltage LV) by the amplification factor setting unit 38d (corresponding to a feedback control step). This reference voltage LV corresponds to the first reference voltage.
For example, the waveform of the voltage signal S2 output from the feedback control means 38 is the waveform shown in the example of “waveform S2” in FIG.
The waveform shown in FIG. 6 (B) “S2 waveform” is an amplifier with respect to the reference voltage LV (first reference voltage) set by the amplification factor setting unit 38d in the waveform shown in FIG. 6 (A) “S1 waveform”. It is shown that feedback control is performed by 38a.

The voltage signal S2 output from the feedback control unit 38 is input to the voltage shift unit 39.
The voltage shift means 39 includes, for example, a low-pass filter 39a, a subtractor 39b, an adder 39c, a 0V adjustment width setting device 39d, and an amplification factor setting device 38d.
The voltage signal S2 passes through the low-pass filter 39a and a high-frequency noise component sufficiently higher than the defect signal is removed.
The signal output from the low pass filter 39a is input to the subtractor 39b. Note that the input of the subtractor 39b is also connected to the output of an adder 39c to which a 0V adjustment width setting unit 39d and an amplification factor setting unit 38d are connected, and the signal input from the low-pass filter 39a is converted to a reference potential ( 0 [V]). For example, when the waveform of the voltage signal S3 output from the subtractor 39b is measured with an oscilloscope or the like, the waveform shown in the example of “S3 waveform” in FIG. 6C is obtained (in FIG. 6C, “S3 waveform” is , The result of inverting the positive and negative so that the defect signal protrudes to the positive side (+ side) is shown.
The reference voltage S2c (see FIG. 5) set by the amplification factor setting unit 38d with respect to the signal output from the low-pass filter 39a is finely adjusted by the 0V adjustment width setting unit 39d, and the voltage signal S3b passing through the adder 39c is adjusted. If the level is shifted by the subtractor 39b, the normal surface level signal can be superimposed on the 0 [V] position (corresponding to the second reference voltage). In this case, the defect signal becomes a negative signal, and if the voltage signal is inverted, the waveform shown in FIG. 6C “waveform of S3” is obtained (the inverting circuit is not shown).
The waveform shown in FIG. 6 (C) “S3 waveform” is equal to the waveform shown in FIG. 6 (B) “S2 waveform” by the reference voltage LV (first reference voltage) set by the amplification factor setting unit 38d. It is shown that the level is automatically shifted (shifted to the 0 [V] position (second reference voltage), which corresponds to a voltage shift step) and further inverted. Note that if the subsequent smoothing means 34, defect emphasis means 36, and determination means 37 are performed with a negative signal, they need not be inverted.

The voltage signal S3 output from the voltage shift means 39 (see FIG. 6C, “S3 waveform”) is input to the smoothing means 34 and the defect enhancement means 36.
The smoothing means 34 smoothes the peak value of the input voltage signal S3 (see the “S4 waveform” in FIG. 6D) in which the peak values of each waveform are smoothly connected. Output (corresponds to the smoothing step).
The defect emphasizing means 36 is, for example, a polygonal line amplifying means, and amplifies the voltage signal S2 greater than or equal to the peak value Vp of the smoothed signal S4 input from the smoothing means 34 and the voltage signal S2 that is less than the peak value Vp. Is cut or attenuated (corresponding to a defect enhancement step). The position of the voltage Vp at the polygonal inflection point is variable and can be input from the outside, and the Vp is given from the smoothing means 34.
As a result, the defect emphasizing means 36 uses the determination signal S5 in which the defect signal is emphasized from the voltage signal S3 having the defect signal having a peak value slightly higher than the surrounding noise component (FIG. 6E, “S5 waveform”). Output). Note that the defect signal can be emphasized more than the surrounding noise component (the peak value can be made higher) by setting the slope of the gain equal to or higher than the peak value Vp in the polygonal line amplification means to be larger than 1.0.

The determination means 37 is constituted by, for example, a voltage comparator 37A and a comparison voltage setter 37d, and outputs a defect detection pulse S6 when detecting a determination signal S5 that is equal to or higher than the threshold voltage S6a set by the comparison voltage setter 37d. . In the example of FIG. 5, a pulse generator 37c is provided at the subsequent stage of the voltage comparator 37A, and when a pulse having a short width is input from the voltage comparator 37A, a defect detection pulse having a predetermined time width T6 is output. (Corresponds to the judgment step). It is possible to recognize whether or not a defect is detected based on the presence or absence of the defect detection pulse S6.
The voltage conversion means 32, feedback control means 38, voltage shift means 39, smoothing means 34, defect emphasis means 36, and determination means 37 described above may be provided for each of the light receiving optical fibers 13b. In order to ensure the area (detectable area) that can be covered by the light receiving optical fiber 13b and the intensity of the detection light output from the light receiving optical fiber 11, a plurality of light receiving optical fibers 13b are provided for each bundled group. May be.

●● [Second Embodiment (FIGS. 7 and 8)]
In the second embodiment, the arrangement state of the emission surface of the light projecting optical fiber and the incident surface of the light receiving optical fiber in the first embodiment shown in FIG. 2A and FIG. In contrast, as shown by W in FIG. 7, the light receiving optical fiber is configured by a pair (13b1, 13b2) (see the “P” portion of W in FIG. 7) and the configuration of the signal processing means 21 is the first. This is different from the first embodiment.
In addition, the point to which the to-be-inspected member S is a material which reflects detection light is the same as that of 1st Embodiment.
When the emission surface of the light projecting optical fiber and the incident surface of the light receiving optical fiber are moved relative to the wall surface M so as to maintain a certain distance GA or GB from the wall surface M, one of the light receiving optical fibers The incident surface of the other light receiving optical fiber 13b2 is moved so as to pass through the same position on the wall surface M following the incident surface of 13b1.

● [Schematic structure of control device for determining defects and schematic waveform of detection signal (FIGS. 7 and 8)]
FIG. 7 shows a schematic configuration of the signal processing means 21 in the control device 30, and FIG. 8 shows a detailed configuration and an example of a waveform (signal). The waveform example shown in FIG. 8 is a waveform measured by an oscilloscope as in the first embodiment, and the horizontal axis indicates time [S] and the vertical axis indicates voltage [V].
As shown in FIG. 7, the signal processing means 21 in the control device 30 includes a light source 31, a first voltage conversion means 32A, a second voltage conversion means 32B, a differential calculation means 33, a smoothing means 34, a defect enhancement means 36, Determination means 37 is provided.
Further, the emission surface of the light projecting optical fiber 13a and the light incident surfaces of the light receiving optical fibers 13b1 and 13b2 are arranged in parallel so as to maintain a constant distance GA or GB from the surface (wall surface M) of the member S to be inspected. .

As shown in FIGS. 7 and 8, the first detection light output from the emission surface of one of the light receiving optical fibers 13b1 is input to the first voltage conversion means 32A, and the first voltage conversion means 32A is input A first electric signal (first voltage signal) S11 corresponding to the intensity of the first detection light is output (see “waveforms of S11 and S12” in FIG. 8). In the example shown in FIG. 8, the first detection light is converted into an electric signal by the photodiode D1a, and further amplified by the amplifier 32a to obtain the first voltage signal S11 (corresponding to the first voltage conversion step).
In addition, the second detection light output from the emission surface of the other light receiving optical fiber 13b2 is input to the second voltage conversion means 32B, and the second voltage conversion means 32B corresponds to the intensity of the input second detection light. The second electrical signal (second voltage signal) S12 is output (see “waveforms of S11 and S12” in FIG. 8). In the example shown in FIG. 8, the second detection light is converted into an electric signal by the photodiode D1b, and further amplified by the amplifier 32b to obtain the second voltage signal S12 (corresponding to the second voltage conversion step).
Since the second voltage signal S12 converts the reflected light from the same position on the wall surface M into a voltage with respect to the first voltage signal S11, the incident surface of one light receiving optical fiber 13b1 and the other light receiving light. The waveform is delayed by a minute time ΔT corresponding to the distance ΔL from the incident surface of the fiber 13b2 and the moving speed of relative movement along the wall surface M.

Then, the first voltage signal S11 and the second voltage signal S12 are input to the differential calculation means 33, and a differential signal indicating the difference between the first voltage signal S11 and the second voltage signal S12 is output from the differential calculation means 33 (difference). Equivalent to a dynamic calculation step). For example, the differential operation means 33 is a differential amplifier. Since the second voltage signal S12 has a waveform delayed by a minute time ΔT with respect to the first voltage signal S11, the differential signal S13 output from the differential operation means 33 is expressed as “S13 waveform” in FIG. The waveform is as shown. (Operation)
The first voltage conversion means 32A, the second voltage conversion means 32B, and the differential calculation means 33 are connected to the photodiodes D1a and D1b (with detection light converted into electric signals) with opposite polarities as shown in 32C of FIG. The signal conversion means) for conversion may be replaced with a circuit connected to the differential operation means 33.
The difference signal S13 output from the differential operation means 33 is input to the smoothing means 34 and the defect enhancement means 36. The smoothing unit 34 includes, for example, a full-wave rectifying unit 34A, a smoothing circuit 34B, and an inverting amplifier 34C. The difference signal S13 is a signal having an amplitude on the positive side and the negative side with a center of substantially zero [V]. Therefore, a signal that has passed through the full-wave rectifier 34A is input to the smoothing circuit 34B, and a smoothed signal is obtained (smoothly connected to the peak value of each waveform) by smoothing the peak value of the differential signal S13. Corresponds to the conversion step).
Then, the smoothing signal S14 (positive potential Vp) output from the smoothing circuit 34B and the smoothing signal S15 (negative potential −Vp) obtained by inverting the smoothing signal S14 to the negative side by the inverting amplifier 34C are defect-emphasized. The data is input to the means 36 (see “S14 and S15 waveforms” in FIG. 8).

The defect emphasizing means 36 is, for example, a polygonal line amplifying means, amplifies the difference signal S13 which is equal to or higher than the peak value Vp of the smoothed signal S14 (positive potential) input from the smoothing means 34 and is less than the peak value Vp The differential signal S13 (positive signal from zero [V] to Vp [V]) is cut or attenuated (corresponding to a defect enhancement step).
Further, the defect emphasizing means 36 amplifies the difference signal S13 equal to or larger than the peak value | −Vp | of the smoothed signal S15 (negative potential) input from the smoothing means 34 and is less than the peak value | −Vp |. The differential signal S13 (negative signal from zero [V] to -Vp [V]) is cut or attenuated.
Thus, the positions of the voltages Vp and −Vp at the polygonal inflection points are variably configured to be input from the outside, and the Vp and −Vp are given from the smoothing means 34.
Thereby, the defect emphasizing means 36 determines signal S16 in which the defect signal is emphasized from the differential signal S13 having the defect signal having a peak value slightly higher than the surrounding noise component (see “waveform of S16” in FIG. 8). Is output. Note that the defect signal can be emphasized more than the surrounding noise component (the peak value can be made higher) by setting the slope of the gain equal to or higher than the peak value Vp in the polygonal line amplification means to be larger than 1.0.

The determination unit 37 is constituted by, for example, a positive side voltage comparator 37A, a negative side voltage comparator 37B, a comparison voltage setting unit 37d, and an OR gate 37D.
When the voltage comparator 37A detects a determination signal S16 that is equal to or higher than the threshold voltage | S18 | [V] set by the comparison voltage setting unit 37d, it outputs a defect detection pulse.
When the voltage comparator 37B detects the determination signal S16 that is equal to or lower than the threshold voltage − | S18 | [V] set by the comparison voltage setting unit 37d, it outputs a defect detection pulse.
In the example of FIG. 8, pulse generators 37c1 and 37c2 are provided at the subsequent stage of the voltage comparators 37A and 37B. When a pulse having a short width is input from the voltage comparators 37A and 37B, a predetermined time width T17 (T17 + ΔT When the minute time ΔT can be ignored, a defect detection pulse having T17) is output. The OR gate 37D outputs a defect detection pulse S17 indicating the logical sum of the input pulses. It can be recognized whether or not a defect is detected based on the presence or absence of the defect detection pulse S17.

●● [Third Embodiment (FIG. 9A)]
In the third embodiment, with respect to the emission surface of the light projecting optical fiber 13a and the light incident surface of the light receiving optical fiber 13b in the first embodiment shown in FIGS. 2 (A) and 3 (A), A point where the distance D between the light exit surface of the light projecting optical fiber 13a and the light incident surface of the light receiving optical fiber 13b is arranged so as to keep a constant distance (see FIG. 9C); The difference is that the member S to be inspected is a material that transmits the detection light without reflecting it.
The detection unit 13A on which the emission surface of the light projecting optical fiber 13a is arranged is provided at the tip of the first support unit 11A, and the detection unit 13B on which the incident surface of the light receiving optical fiber 13b is arranged is a second support. It is provided at the tip of the part 11B.

When inspecting the defect of the inspection target member S made of a material that transmits the detection light, first, the detection light emitted from the emission surface of the light projecting optical fiber 13a and transmitted through the inspection target member S is incident on the incident surface of the light reception optical fiber 13b. Is incident on.
Then, the light exiting optical fiber 13a and the light receiving optical fiber 13b incident surface are moved relative to the member S to be inspected along the surface of the member S to be inspected. The defect of the member to be inspected S is determined based on the change in the intensity of the detection light incident on the incident surface. In the case of the example shown in FIG. 9A, the detection pipe 10 may be moved along the side surface of the member S to be inspected, or the member S to be inspected may be moved without moving the detection pipe 10.
The signal processing means 21 is the same as that of the first embodiment shown in FIGS.

●● [Fourth embodiment (FIG. 9B)]
With respect to the emission surface of the light projecting optical fiber 13a and the light incident surfaces of the light receiving optical fibers 13b1 and 13b2 in the second embodiment shown in FIG. The point D is arranged so that the distance D between the emission surface 13a and the incident surfaces of the light receiving optical fibers 13b1 and 13b2 is kept constant (see FIG. 9C), and the inspection object The difference is that the member to be inspected S is a material that transmits the detection light without reflecting it.
The detection unit 13A in which the emission surface of the light projecting optical fiber 13a is arranged is provided at the tip of the first support unit 11A, and the detection unit 13B in which the incident surfaces of the light receiving optical fibers 13b1 and 13b2 are arranged is 2 is provided at the tip of the support portion 11B.

When inspecting a defect in the inspection target member S made of a material that transmits the detection light, first, the detection light emitted from the emission surface of the light projecting optical fiber 13a and transmitted through the inspection target member S is received by the light receiving optical fibers 13b1 and 13b2. Incident on the incident surface.
Then, the emission surface of the light projecting optical fiber 13a and the light incident surfaces of the light receiving optical fibers 13b1 and 13b2 are moved relative to the member S to be inspected along the surface of the member S to be inspected. The defect of the member to be inspected S is determined based on the change in the intensity of the detection light incident on the incident surfaces of the fibers 13b1 and 13b2. In the example shown in FIG. 9B, the detection pipe 10 may be moved along the side surface of the member S to be inspected, or the member S to be inspected may be moved without moving the detection pipe 10.
The signal processing means 21 is the same as that of the second embodiment shown in FIGS.

The defect inspection apparatus 1 of the present invention is not limited to the appearance, configuration, inspection procedure and the like described in the present embodiment, and various modifications, additions, and deletions can be made without changing the gist of the present invention.
The numerical values used in the description of the present embodiment are examples, and are not limited to these numerical values.
In the description of the present embodiment, an example of a cylinder having a cylindrical space as the member S to be inspected has been described. However, the emission surface of the light projecting optical fiber 13a and the light receiving optical fiber 13b (13b1, 13b2) are described. Are arranged in parallel so as to maintain a certain distance from the surface of the member S to be inspected, and move relative to the member S to be inspected along the surface of the member S to be inspected (the member to be inspected detects light). Or the incident surface of the light receiving optical fiber 13b (13b1, 13b2) are opposed to each other so as to maintain a certain distance across the member S to be inspected. As long as the member S is moved relative to the member S along the surface of the member S (when the member S transmits the detection light), the member S may have any shape. . For example, the member S to be inspected may be plate-shaped.
The detailed circuit of the signal processing means 21 is not limited to the circuit described in the present embodiment.
Further, the above (≧), the following (≦), the greater (>), the less (<), etc. may or may not include an equal sign.
Further, the amplification characteristic of the defect emphasizing means 36 may not be a characteristic that gradually increases the amplification factor, but may be a characteristic that increases the amplification factor stepwise.

  The defect inspection method and the defect inspection apparatus 1 according to the present invention are not limited to the cylinders described in the present embodiment, such as an engine cylinder and a brake cylinder of a vehicle, but include inner peripheral wall surfaces such as various cylinders, pipes, and machining holes. First, the present invention can be applied to detection of a defect in a member to be inspected of various shapes and a member to be inspected that is made of a material that reflects detection light or a material that transmits detection light.

It is a figure explaining one Embodiment of the structure of 1st Embodiment in the defect inspection apparatus 1 of this invention, and the structure of the detection pipe 10 which comprises the defect inspection apparatus 1. FIG. It is a figure explaining the structure and defect inspection procedure of the detection part 13 in 1st Embodiment. It is a figure explaining another structural example and defect inspection procedure in the detection part 13 of 1st Embodiment. It is a figure explaining the schematic structure of the signal processing means 21 in 1st Embodiment, and the outline | summary of the determination method of a defect. It is a figure explaining the detailed structure of the signal processing means 21 in 1st Embodiment, and the example of a voltage waveform. It is a figure explaining the schematic structure of the signal processing means 21 in 2nd Embodiment, and the outline | summary of the determination method of a defect. It is a figure explaining the example of a detailed structure of the signal processing means 21 in 2nd Embodiment. It is a figure explaining the example of the voltage waveform of each part of the signal processing means 21 in 2nd Embodiment. The arrangement of the incident surface of the light projecting optical fiber 13a and the light receiving optical fibers 13b (13b1, 13b2) in the third embodiment (FIGS. 9A and 9C), and the light projecting in the fourth embodiment. It is a figure explaining the arrangement | positioning (FIG. 9 (B) and (C)) of the entrance plane of the optical fiber 13a for light, and the optical fiber 13b (13b1, 13b2) for light reception.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Defect inspection apparatus 10 Detection pipe 11 Insertion part 12 Support part 13 Detection part 13a Optical fiber for light emission 13b, 13b1, 13b2 Optical fiber for light reception 14 Flexible tube 15 Mounting part 21 Signal processing means 22 Drive means 23 Personal computer 30 Control apparatus Reference Signs List 31 light source 32 voltage conversion means 33 differential operation means 34 smoothing means 36 defect emphasis means 37 determination means 38 feedback control means 39 voltage shift means S cylinder (member to be inspected)
ZS axis

Claims (5)

Using a projecting optical fiber and a receiving optical fiber,
A member to be inspected that is arranged so that the emission surface of the light projecting optical fiber and the light incident surface of the light receiving optical fiber face each other so as to maintain a certain distance, and transmits the detection light emitted from the light projecting optical fiber Is disposed between the emission surface of the light projecting optical fiber and the light incident surface of the light receiving optical fiber,
The emission surface of the light projecting optical fiber is moved relative to the member to be inspected along the surface of the member to be inspected, and the light emission surface of the light projecting optical fiber is moved. Determining a defect of the member to be inspected based on a change in intensity of detection light emitted from the member to be inspected and transmitted to the incident surface of the light receiving optical fiber;
A defect inspection method characterized by that. Using a projecting optical fiber and a receiving optical fiber,
When inspecting a member to be inspected that reflects the detection light emitted from the light projecting optical fiber, the light emitting surface of the light projecting optical fiber arranged side by side so as to maintain a certain distance from the surface of the member to be inspected; Moving the incident surface of the light receiving optical fiber relative to the member to be inspected along the surface of the member to be inspected;
When inspecting a member to be inspected that transmits detection light emitted from the light projecting optical fiber, the light exiting surface of the light projecting optical fiber opposed to maintain a certain distance across the member to be inspected and the Move the incident surface of the light receiving optical fiber relative to the member to be inspected along the surface of the member to be inspected,
A voltage conversion step of converting the detection light incident on the light receiving optical fiber into a voltage signal corresponding to the intensity of the detection light;
A feedback control step including a feedback unit that shifts the voltage signal output from the voltage conversion step to a preset first reference voltage and removes the swell component of the voltage signal;
A voltage shift step for shifting the voltage signal output from the feedback control step to a preset second reference voltage;
The voltage signal output from the voltage shift step amplifies a voltage signal whose peak value is greater than or equal to the external input voltage, and cuts or attenuates a voltage signal whose peak value is less than the external input voltage to emphasize the defect signal. A defect emphasizing step for obtaining a determined determination signal;
A determination step of determining a signal having a peak value equal to or higher than a first predetermined voltage as a defect in the determination signal;
Furthermore, it has a smoothing step for smoothing the peak value of the voltage signal output from the voltage shift step, and uses the smoothed signal output from the smoothing step as the external input voltage in the defect emphasizing step.
A defect inspection method characterized by that. Using a projecting optical fiber and a receiving optical fiber,
When inspecting a member to be inspected that reflects the detection light emitted from the light projecting optical fiber, the light emitting surface of the light projecting optical fiber arranged side by side so as to maintain a certain distance from the surface of the member to be inspected; Moving the incident surface of the light receiving optical fiber relative to the member to be inspected along the surface of the member to be inspected;
When inspecting a member to be inspected that transmits detection light emitted from the light projecting optical fiber, the light exiting surface of the light projecting optical fiber opposed to maintain a certain distance across the member to be inspected and the Move the incident surface of the light receiving optical fiber relative to the member to be inspected along the surface of the member to be inspected,
When the light receiving optical fiber is configured as a pair and relatively moved along the surface, the light receiving optical fiber incident surface of the other light receiving optical fiber is the same as the light receiving optical fiber on the surface. Move it past the position,
A first voltage conversion step of converting the first detection light incident on one of the light receiving fibers into a first voltage signal corresponding to the intensity of the first detection light;
A second voltage conversion step of converting the second detection light incident on the other light receiving fiber into a second voltage signal corresponding to the intensity of the second detection light;
A differential operation step of obtaining a difference signal indicating a difference between the first voltage signal and the second voltage signal;
A smoothing step of obtaining a smoothed signal obtained by smoothing the peak value of the differential signal;
From the difference signal and the smoothed signal, a signal that is equal to or higher than the peak value of the smoothed signal in the difference signal is amplified, and a signal that is less than the peak value of the smoothed signal in the difference signal is cut or attenuated. A defect enhancement step for obtaining a determination signal in which the defect signal is enhanced;
A determination step of determining a signal having a peak value equal to or higher than a second predetermined voltage as a defect in the determination signal;
A defect inspection method characterized by that. A light emitting optical fiber, a light receiving optical fiber, and a control device;
When inspecting a member to be inspected that reflects the detection light emitted from the light projecting optical fiber, the light emitting surface of the light projecting optical fiber arranged side by side so as to maintain a certain distance from the surface of the member to be inspected; Moving the incident surface of the light receiving optical fiber relative to the member to be inspected along the surface of the member to be inspected;
When inspecting a member to be inspected that transmits detection light emitted from the light projecting optical fiber, the light exiting surface of the light projecting optical fiber opposed to maintain a certain distance across the member to be inspected and the Move the incident surface of the light receiving optical fiber relative to the member to be inspected along the surface of the member to be inspected,
The controller is
When the detection light incident on the light receiving optical fiber is input, voltage conversion means for outputting a voltage signal according to the intensity of the input detection light;
A feedback control unit having a feedback unit that shifts the voltage signal output from the voltage conversion unit to a first reference voltage set in advance and removes the undulation component of the voltage signal;
Voltage shift means for shifting the voltage signal output from the feedback control means to a preset second reference voltage;
The voltage signal output from the voltage shift means amplifies a voltage signal whose peak value is greater than or equal to the external input voltage, and cuts or attenuates a voltage signal whose peak value is less than the external input voltage to emphasize the defect signal. Defect enhancement means for outputting the determined determination signal;
When the determination signal is input, a determination unit that determines a signal having a peak value equal to or higher than the first predetermined voltage in the input determination signal as a defect,
Furthermore, it comprises smoothing means for smoothing the peak value of the voltage signal output from the voltage shift means, and the smoothed signal output from the smoothing means is input to the defect emphasis means as the external input voltage.
A defect inspection apparatus characterized by that. A light emitting optical fiber, a light receiving optical fiber, and a control device;
When inspecting a member to be inspected that reflects the detection light emitted from the light projecting optical fiber, the light emitting surface of the light projecting optical fiber arranged side by side so as to maintain a certain distance from the surface of the member to be inspected; Moving the incident surface of the light receiving optical fiber relative to the member to be inspected along the surface of the member to be inspected;
When inspecting a member to be inspected that transmits detection light emitted from the light projecting optical fiber, the light exiting surface of the light projecting optical fiber opposed to maintain a certain distance across the member to be inspected and the Move the incident surface of the light receiving optical fiber relative to the member to be inspected along the surface of the member to be inspected,
The light receiving optical fiber is configured as a pair, and when the light receiving optical fiber is relatively moved along the surface, the light receiving optical fiber incident surface is followed by the light receiving optical fiber incident surface on the surface. Move to pass the same position of
The controller is
A first voltage conversion means for outputting a first voltage signal corresponding to the intensity of the input first detection light when the first detection light incident on one of the light receiving fibers is input;
A second voltage conversion means for outputting a second voltage signal corresponding to the intensity of the input second detection light when the second detection light incident on the other light receiving fiber is input;
Differential operation means for outputting a difference signal indicating a difference between the input first voltage signal and the second voltage signal when the first voltage signal and the second voltage signal are input;
Smoothing means for outputting a smoothed signal obtained by smoothing the peak value of the differential signal;
When the differential signal and the smoothed signal are input, a signal that is equal to or higher than the peak value of the smoothed signal in the differential signal is amplified, and a signal that is less than the peak value of the smoothed signal in the differential signal is A defect emphasizing means for outputting a determination signal in which the defect signal is emphasized by cutting or attenuation; and
When the determination signal is input, a determination unit that determines a signal having a peak value equal to or higher than a second predetermined voltage in the input determination signal as a defect,
A defect inspection apparatus characterized by that.

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