JP2698697B2 - Surface flaw inspection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a surface flaw inspection method capable of detecting a surface flaw of a test object such as a band-like body or a sheet-like object with high accuracy.

[Prior art]

2. Description of the Related Art In recent years, strips such as steel plates and coated steel plates have been required to have more accurate surface flaw inspection in order to improve product quality. For example, the thickness of a coated steel sheet has become thinner year by year, and accordingly, a coating covering the surface has become very thin. As described above, as the coating becomes thinner, the production of coated steel sheet becomes more difficult, and at the same time, a pattern defect due to thickness unevenness or the like, a surface defect that is difficult to detect such as a discoloration defect tends to occur. is there. Therefore, there is a demand for a highly accurate surface flaw inspection technique for coated steel sheets. By the way, as a surface flaw inspection apparatus conventionally used, for example, a laser reflection type apparatus shown in FIG. 10 and a laser diffraction type apparatus shown in FIG. 11 are known. The apparatus shown in FIG. 10 includes a laser oscillator 10 as a light source, an optical lens 12 for forming a laser beam oscillated from the oscillator 10 into a spot, and a laser beam formed in a spot shape scanned in the width direction of the steel sheet S. Rotating mirror 14 and the steel plate S
And a diffuse reflection light receiver 16A and a regular reflection light receiver 16B composed of a silicon (Si) cell or the like for detecting a laser beam reflected on the surface of the light source. In this device, the reflected light of the laser beam scanned on the surface of the steel sheet S traveling in the direction of the arrow is detected by the light receivers 16A and 16B for irregular reflection and regular reflection, and the respective detection signals are amplified by amplifiers 18A and 18B. Is input to the analog computing unit 20 through the CPU and performs a predetermined computation, thereby detecting the surface flaw of the steel sheet S. The apparatus shown in FIG. 11 detects surface flaws by utilizing the diffraction phenomenon of light, and uses a laser oscillator 10 as a light source.
And a collimator 12A that makes the laser beam oscillated from the oscillator 10 into a spot shape, and the spot-like luminous flux is
, A rotary mirror 14 that scans in the width direction, an objective lens (Fresnel lens) 22 for condensing the laser light reflected on the steel plate surface, and a spatial filter ( And a photomultiplier (photomultiplier) 26 for detecting a laser beam incident through the mask 24. In this device, reflected light reflected by the surface of the steel sheet S traveling in the direction of the arrow and entering through the objective lens 22 and the spatial filter 24 is detected by the photomultiplier tube 26, and not shown based on the detection signal. The surface flaw is detected by the calculation by the calculation device. The spatial filter 24 is a so-called mask having a function of extracting a diffraction pattern peculiar to surface flaws from a diffraction pattern light beam that is reflected light. In each of the two surface defect inspection methods described above, since the light source is a laser, the light used is of a single wavelength, and the light receiving unit also has a function of detecting the intensity of the monochromatic light. There are also devices using white light as a light source, but these are based on a single color in which the photodetector can only output a change in the intensity of the reflected light, and the basic function is that of the 10th.
It is substantially the same as the apparatus shown in FIG. 11 or FIG.

[Problems to be solved by the invention]

However, when detecting surface flaws based on a change in the intensity of reflected light based on a single color as described above, a pattern defect generated on the surface of the test object, for example, a coated steel sheet having an insulating film. There is a problem that it is difficult to detect a surface flaw accompanied by a color such as a subtle pattern defect or a discoloration defect caused by the defect. FIG. 12 shows this concretely. FIG. 12 is a laser diffraction type surface flaw inspection apparatus corresponding to the apparatus shown in FIG. 11, and when laser light is scanned in the width direction of the steel sheet S, light reflected on the surface of the steel sheet S FIG. 7 is a diagram showing a scanning waveform (upper) of an output voltage of the photomultiplier tube 26 receiving light and a differential waveform (lower) thereof. In the steel sheet S, discoloration has occurred at a position corresponding to the left end of the scanning waveform. It can be seen from the scanning waveform that the discoloration defect cannot be clearly detected.

[Means for achieving the object]

Therefore, the present inventors have conducted various studies to solve the above-mentioned problems, and as a result, the reflected light from the surface of the object to be inspected is received by a plurality of color sensors sensitive to different wavelength ranges, and Conventionally, by detecting surface flaws on the body, it was impossible to accurately detect the surface flaws without the naked eye. We have developed a surface flaw inspection method that can accurately detect surface flaws such as pattern defects and discoloration defects generated on the surface of a test object. That is, since the reflected light on the surface of the inspection object is received by the color sensor and the surface flaw is detected based on the output signal, color information consisting of light in two or more different wavelength ranges is used for the detection of the surface flaw. As a result, it has become possible to accurately detect surface flaws such as the pattern and discoloration, which are difficult to detect with monochromatic-based optical information. An example of the surface flaw inspection method applied to the coated steel sheet will be specifically described with reference to FIG. In the surface flaw inspection method, the fluorescent lamp 30 which is a rod-shaped light source approaching a coated steel plate (band) S is used as an optical system.
An inspection apparatus including a one-dimensional color CCD camera 32 that receives reflected light from the surface of the coated steel sheet S is applied. First, the reflected light reflected by the coated steel sheet S traveling in the direction of the arrow and incident on the color CCD camera 32 is R,
Each of the light receiving elements of G and B is converted into an electric signal, and R, G and B
The following processing is performed in parallel for each corresponding electrical signal. However, for convenience, in the following description, the case of the R signal will be described as a representative. The raw signal, which is the output of the R element, is subjected to differential processing with the R standard in step 100, and the difference signal is output to step 102.
Is output to the binarization process. That is, the difference between the raw signal from the R element shown in FIG. 14 (A) and the R standard signal shown in FIG. The signal is obtained, and the difference signal is obtained in step 102.
Output to In step 102, the binarization levels of r _{1 to} r ₆ are set for each peak of the difference signal shown in FIG. 14C, and binarization is performed for each of these peaks. The result of the binarization process is input to a register for each of ± 3 levels corresponding to the levels r _{1 to} r ₆ and stored (step 104). The binarized signal is extracted from the register, and the characteristic parameters of the surface flaw such as H (length), W (width), D (density), and S (area) are calculated from the signal (step 10).
6) The calculation result is output to the outside as surface flaw information (step 108). Note that the above steps 102 to 10
In each of 8, the welding point detection signal is output from the welding point detector (WPD), the traveling distance signal is output from the pulse generator (PLG), and the detection position of the surface flaw is calculated as the distance from the welding point position. It has been made like that. The above-described signal processing is also performed for each of the G and B color signals, and surface flaw information is created for three colors of R, G and B,
Surface flaws are detected from surface flaw information for each color or information obtained by combining these. Thus, detection of surface flaws
Because it can be performed based on R, G, B color information,
It has become possible to accurately detect delicate surface flaws such as patterns and discoloration, which are difficult to detect on the basis of monochromatic light information, that is, a single change in light intensity. The present inventors have conducted intensive studies to further improve the detection accuracy of patterns, surface flaws such as discoloration, and as a result, by performing predetermined arithmetic processing on output signals based on light in two or more different wavelength ranges, It has been found that the detection accuracy of the surface flaw can be further improved, and the flaw type can be determined. According to a first aspect, based on the above findings, reflected light from the surface of the test object is received by a plurality of color sensors sensitive to each of a plurality of different wavelength ranges, and based on output signals of the respective wavelength ranges from the sensors. In addition to detecting the surface flaws, the arithmetic processing is performed between the output signals in these different wavelength ranges, the surface flaws are detected based on the calculation results, and the flaw type is determined based on the detection results of the respective surface flaws. In the flaw inspection method, when a surface flaw is detected by the color sensor, the surface of the object to be inspected is placed close to the surface, and a reflector for giving light condensing property to the surface is located near the surface. Irradiate with the arranged white rod-shaped light source, and as the color sensor, offset between the reflection position where the optical axis intersects and the irradiation position of the maximum illuminance by the rod-shaped light source on the surface of the inspection object. Also So it disposed a one-dimensional color CCD
By using a camera, the above-mentioned problem is more reliably achieved, and the type of flaw can be determined. In the second invention, the reflected light from the surface of the object to be inspected is received by a plurality of color sensors that are sensitive to each of a plurality of different wavelength ranges, and surface defects are detected based on output signals from the sensors for each of the wavelength ranges. While performing an arithmetic process between the output signals of these different wavelength ranges, detecting a surface flaw based on the arithmetic result, and further detecting the intensity of the reflected light from the surface of the inspection object. A surface flaw inspection method for detecting surface flaws based on the detection results and determining a flaw type based on the detection results of each of these surface flaws. The surface is placed in close proximity to the surface, and a reflector for giving light condensing properties to the surface is irradiated with a white rod-shaped light source disposed in the vicinity, and the color sensor is used as the color sensor. On the surface, the optical axis By using a one-dimensional color CCD camera arranged with an offset between the reflection position to be irradiated and the irradiation position of the maximum illuminance by the rod-shaped light source, the above-described problem is similarly achieved, and the type of flaw is further determined. Is made possible.

[Action and effect]

According to the first aspect, by detecting surface flaws based on output signals (color information) for each wavelength range from a one-dimensional color CCD camera, a single color is detected in the same manner as the surface flaw inspection method of the present inventors. It is possible to accurately detect surface flaws such as patterns and discoloration that are difficult to detect with the base optical information, and to perform arithmetic processing between greening signals in different wavelength ranges to detect some color information. It is possible to detect a low-accuracy flaw type with high accuracy. As described above, since the surface flaw can be detected with high accuracy for each flaw type, the flaw type can be determined. Here, the arithmetic processing includes four arithmetic operations and an averaging process. Further, upon detection, the surface of the object to be inspected is irradiated with a white rod-shaped light source in which a reflector for imparting light condensing property is disposed in the vicinity, and the one-dimensional color CCD camera is placed on the surface. Since the offset position is provided between the reflection position where the optical axis of the camera crosses and the position of the maximum illuminance by the rod-shaped light source, it is possible to appropriately adjust the amount of light incident on the camera. As a result, it becomes possible to accurately detect surface defects (defects) such as fine pattern defects and discoloration defects. FIG. 1 shows the output of each of a red (R) light receiving element and a green (G) light receiving element detected when a color CCD camera was used as a color sensor and a surface of a coated steel sheet where band-shaped baldness was generated was scanned. Diagram showing a voltage scanning waveform (FIG. (A)), and diagram showing a processing waveform obtained by performing addition and multiplication as arithmetic processing between the R and G output signals (FIG. (B)). It is. In the figure, (raw) shows a scanning waveform or a processing waveform of the specific scanning. From this figure, it is shown that, at the site where the surface flaw (band-shaped baldness) occurs, the contrast of the processed waveform is higher than that of the scanning waveform of each of the R and G single signals.
It can be seen that the ratio has been improved. Similarly, FIG. 2 shows a thin film, FIG. 3 shows a base pattern, and FIG. 4 shows a single signal waveform and a processed signal waveform in the case of discoloration as surface flaws, respectively. 2 to 4, it can be seen that the S / N ratio with respect to the surface flaw is improved by performing the arithmetic processing between the single signals. However, FIG. 2 shows the result of addition and multiplication operation processing,
The figure also shows the result of performing an averaging process of performing an average of a plurality of scans. In the figure, AVE indicates that the averaging process has been performed. FIG. 4 shows the results for the R and B output signals. As described above, according to the first aspect, the flaw can be detected with high accuracy by using the single color information, and the surface flaw having a low detection level with the single color information can be calculated by the arithmetic processing between the output signals in different wavelength ranges. It is also possible to improve the S / N ratio, and it is also possible to accurately detect the surface flaw. Therefore, by combining the detection results of the surface flaws described above, appropriate flaw type determination can be performed. Further, in the second invention, similarly to the first invention, a surface flaw such as a pattern is detected with high accuracy, and the surface of the object to be inspected is irradiated with, for example, a laser beam, and intensity information of the reflected light is used. By doing so, it becomes possible to accurately detect a normal defect such as a minute defect that can be easily detected by a change in the intensity of the reflected light. Therefore, by combining the detection results of the surface flaws described above, it is possible to accurately determine a flaw type over a wide range.

【Example】

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 5 is a block diagram for explaining the operation of the first embodiment according to the first invention, and FIG. 6 is a schematic configuration diagram showing a color sensor type surface flaw inspection apparatus applied to this embodiment. The inspection apparatus includes, as an optical system, a fluorescent lamp 40 which is a rod-shaped light source close to a coated steel plate (band) S, and a one-dimensional color CCD camera 42 which receives light reflected from the surface of the coated steel plate S. Have. Further, the inspection apparatus includes a control circuit 44 for driving and controlling the CCD camera 42, and a signal processing circuit for performing a predetermined process on an output signal of the CCD camera 42 input through the control circuit 44.
And an editing processing device (computer) 48 that edits the processing signal from the signal processing circuit 46 and performs processing such as determining a defect for each color. And the editing processing device
From 48, the editing processing signal is input to the conventional surface flaw inspection device 50, and the overall determination of the surface flaw is performed. In the above inspection apparatus, the fluorescent lamp 40, which is a rod-shaped light source,
It is a color rendering AAA class daylight fluorescent lamp with an output of 100W and a lighting frequency of 30KHz. It is preferable that the fluorescent lamp be close to natural light and be high-frequency lighting or DC lighting.
Further, in order to combine with the color CCD camera 42, it is preferable that the power spectrum in the visible light region is as uniform as possible. The one-dimensional color CCD camera 42 is a one-dimensional linear array sensor capable of detecting three colors of red (R), green (G) and blue (B) with a filter. B
It has a color sensor formed of 864 bits each, and a lens with a focal length of f35 mm and brightness of F3.5. As shown in FIG. 7, the spectral characteristics of the color CCD camera 42 are close to human luminosity characteristics. In the present embodiment, the color CCD camera 42 scans at a speed of 2 KHz. The optical system of the inspection device will be described in more detail. The fluorescent lamp 40 and the color CCD camera G42 were arranged in the positional relationship shown in FIG. That is, the coated steel sheet S
The distance L ₁ from the surface to the light receiving surface of the CCD camera 42 110
0 mm, the distance L ₂ from the center of the fluorescent lamp 40 to the irradiation surface (point) with the maximum illuminance is 110 mm, and the reflection of vertical reflected light (θ ₁ = 90 °) incident on the optical axis passing through the lens center of the CCD camera 42 The offset ΔL, which is the distance between the position and the irradiation surface (position) with the maximum illuminance, is 37 mm, and θ ₂ between the irradiation axis from the center of the fluorescent lamp 40 to the irradiation surface with the maximum illuminance and the perpendicular to the steel plate S is
20 mm. It should be noted that a reflector 40A is provided near the fluorescent lamp 40 in order to provide light condensing properties to the surface of the steel sheet S.
Further, the distance L ₁ is calculated from the resolution required per 1bit against scratches, the distance L ₂ determines seeking illuminance required empirically, offset ΔL was also determined experimentally optimum value. Also, the angle θ ₁ is an angle that is least affected by the pass line fluctuation,
Angle theta ₂ was adjusted so that the S / N ratio of flaw is maximized. As described above, the offset ΔL is added to the arrangement of the fluorescent lamp 40.
, The amount of light incident on the CCD camera can be reduced. By appropriately adjusting the amount of incident light, it is possible to prevent the scattering of color information due to the amount of incident light being too large, and as a result, it becomes possible to accurately detect subtle surface defects. Next, the operation of this embodiment will be described with reference to FIG. First, a procedure for detecting a surface flaw using a color increase in a different wavelength region as it is in the same manner as the above-described surface flaw inspection method by the present inventors will be described. In this embodiment,
The output signal of the blue (B) light receiving element is not used. Reflected by the coated steel sheet S running in the direction of the arrow,
The reflected light incident on the color CCD camera 42 is converted into electric signals by the R and G light receiving elements, and the following processing is performed in parallel for each of the electric signals corresponding to R and G.
In the following description, the case of the R signal will be described as a representative,
Similar processing is performed for the G signal. The raw signal, which is the output of the R element, is subjected to differential processing with the R standard in step 200, and the difference signal is processed in step 202.
Is output to the binarization process. That is, as in the case of the surface flaw inspection method shown in FIG. 13 described above, the raw signal from the R element shown in FIG. 14A corresponds to the output signal when a defect-free sample is used. The difference signal of FIG. 10C is obtained by subtracting the R standard signal of FIG.
Output to 2. The differential processing has the following major features. That is,
The R standard signal is created by storing a total level signal on the system including the power spectrum difference in the width direction of the fluorescent lamp 30, the lens aberration, and the like. Then, by performing a differential process between the R standard signal and the raw signal, a signal change, a color level, and a gradation when a reflected light from the coating surface is received can be accurately extracted.
As a result, the binarization process in the next step 202 can be reliably performed. Therefore, it is possible to detect even a small surface change at a high S / N ratio, which has not been possible with the conventionally used differential processing or filter processing. At step 202, as in the case of surface flaw inspection method shown in the FIG. 13, for each peak of the difference signal shown in FIG. 14 (C), the binarization level r ₁ ~r ₆ respectively Then, binarization is performed for each of these peaks. The binarization result of the process, the ± 3 level corresponding to the level r ₁ ~r _6, is input to the register for each level is stored (step 204). Extracting a binary signal from the register,
Parameter calculation is performed using surface flaw characteristic parameters such as H (length), W (width), D (density), and S (area) (step 206), and the calculation result is sent to the outside as surface flaw information. Output (Step 208). Step 2 above
From 02 to step 208, weld point detector (WPD)
, A travel distance signal is output from the pulse generator (PLG), and the detected position of the surface flaw is calculated as a distance from the weld point position. The above-described arithmetic processing is also performed on the G signal, and R,
Surface flaw information is created for two colors G, and surface flaws are detected from surface flaw information for each color and information obtained by combining these. At the same time as the above-described signal processing, the arithmetic processing of multiplication (step 212) and addition (step 214) is performed between the R signal and the G signal in step 210. The multiplication signal obtained in step 212 is subjected to differential processing with the R × G standard in step 200, and the difference signal is subjected to the same signal processing as in steps 202 to 208. Do. Similarly, the addition processing signal obtained in step 214 is subjected to differential processing with the R + G standard, and the signal processing in steps 202 to 208 is performed on the difference signal. As described above, since the detection of the surface flaw can be performed based on the color information of R and G, the pattern cannot be detected based on monochromatic light information, that is, a single light intensity change. When it is possible to accurately detect delicate surface flaws such as discoloration, and at the same time, by performing arithmetic processing between the R and G signals, the R and G signals are used as raw signals It is possible to easily detect flaw types that are difficult to detect due to low S / N ratio. As described above, since the detection accuracy for each flaw type can be improved, by inputting parameters relating to surface flaws obtained by signal processing to, for example, a neural network for determining the flaw type, the flaw type can be accurately detected. It is possible to determine. Table 1 below shows the results of actually applying the method of this example to coated steel sheets. In the table, ○ indicates that the flaw detection is very effective, Δ indicates that the flaw detection is effective, and X indicates that the flaw detection is impossible. From the above Table 1, it is possible to detect general flaws by the raw color signal, and it is possible to accurately detect patterns and flaws of the discoloration system, which have been difficult to detect in the past. It can be seen that the detection accuracy of rust traces is further improved than that of raw signals. Further, as described above, since the surface flaw can be detected with high accuracy for each flaw type, highly accurate flaw type determination can be performed by using an appropriate flaw type determination logic. In this embodiment, by using a one-dimensional color CCD camera as the color sensor, the rod-shaped light source, that is, the fluorescent lamp 40, can be used as the light source as described above, and the light source can be made uniform. . Similarly, by using a one-dimensional sensor, it has become possible to obtain a continuous two-dimensional image as the object to be inspected moves. As a result, an expensive image processing device required for the two-dimensional sensor is not required, and the device can be simplified. That is, a two-dimensional color sensor, for example, a two-dimensional color CCD camera, is used to fetch a planar image into an image memory, and to perform feature extraction by a general-purpose image processing device. However, for example, it is extremely difficult to obtain uniform illumination over a large area of 1.5 m × 1.5 m, and since a general-purpose image processing device does not have real-time processing capability, a large number of processing devices are required. However, there are disadvantages such as an expensive system. FIG. 9 is a schematic configuration diagram showing a surface flaw inspection apparatus applied to the second embodiment according to the second invention. The inspection apparatus includes a color sensor type surface flaw inspection apparatus 60 disposed on the left side of the drawing and a laser diffraction type surface flaw inspection apparatus 62 disposed on the right side, and is integrally formed as an inspection system. The processing results of the two inspection devices 60 and 62 are input to the data processing / editing processing device 64, and the surface flaw is determined. The color sensor type surface flaw inspection apparatus 60 is substantially the same as that applied to the first embodiment, and a portion 66 surrounded by a two-dot chain line is the fluorescent lamp 40 shown in FIG. It corresponds to the one-dimensional color CCD camera 42 and the control circuit 44.
The output signal from the control circuit 44 is input to the signal processing device 46A, and the output signal of the processing device 46A is input to the editing processing device 64. Also, in the laser diffraction type surface flaw inspection apparatus 62, a portion 68 surrounded by a two-dot chain line corresponds to substantially the same apparatus as the apparatus shown in FIG. An output signal of the multiplier 26 is input to the editing processing device 64 via the control device 70. As shown in FIG. 9, the inspection apparatus having the above-described configuration was installed in a final line for coil winding, and a surface defect inspection of the coated steel sheet S located immediately before winding on the coil C was performed. The results are shown in Table 2 below. Measurement was performed on a coated steel plate with a width of 800 to 1300 mm, 200 mp
It was run at a speed of m. The operating conditions of the color sensor type inspection device 60 were the same as those of the first embodiment, and the laser diffraction type inspection device 62 used a 2 mW He-Ne laser as a light source. From the above Table 2, in the color sensor type inspection device 60,
By using the R and G color raw signals and the color operation signals, it is possible to detect defects such as patterns and discoloration which were difficult to detect with high accuracy in the past. Since normal defects such as scabs and scratches can be detected with high accuracy, surface flaws such as bamboo scabs, which are difficult to detect with a color raw signal or a color operation signal, are detected in monochrome by a laser diffraction type inspection device 62. Therefore, it is possible to accurately detect a wide range of flaw types. Further, as described above, since a surface flaw can be detected with high accuracy for each flaw type, it is possible to determine a flaw type over a wide range with high accuracy by using an appropriate flaw type determination logic. As described above, the present invention has been specifically described. However, it goes without saying that the surface flaw inspection method of the present invention is not limited to the above-described embodiment. For example, as the color sensor, R shown in the embodiment,
The camera is not limited to a one-dimensional color CCD camera that can sense three colors of G and B, and is not particularly limited as long as it can sense light of at least two different wavelength ranges or more. Except those who do). In addition,
The wavelength range referred to here includes light of a single wavelength, as well as a case where it has a certain spread. Also, the color output signal used for detection is not limited to R and G, and it goes without saying that an output signal for light in another wavelength range such as B can be used according to the type of flaw. Also, the signal processing is not limited to addition and multiplication.
Other four arithmetic operations and averaging processing may be performed. Further, the light source is not limited to a fluorescent lamp, but may be a xenon lamp or the like.

[Brief description of the drawings]

1, 2, 3, and 4 are diagrams for explaining the operation of the present invention, respectively, FIG. 5 is a block diagram for explaining the operation of the first embodiment, FIG. 6 is a schematic configuration diagram showing a surface flaw inspection apparatus applied to the first embodiment, FIG. 7 is a diagram showing a spectral characteristic of a color CCD camera of the inspection apparatus, and FIG. FIG. 9 is a schematic configuration diagram showing an enlarged main part of the apparatus, FIG. 9 is a schematic configuration diagram showing a surface flaw inspection apparatus applied to the second embodiment, and FIG. 10 is a conventional laser reflection type surface flaw inspection apparatus. FIG. 11 is a schematic perspective view showing a conventional laser diffraction type surface flaw inspection device, FIG. 12 is a diagram showing surface flaw detection results by a conventional surface flaw inspection device, FIG. FIG. 14 is a block diagram showing a procedure for detecting a flaw based on each output signal of R, G, and B from the color sensor. A diagram for explaining a differential process performed on the output signal of the color CCD camera. 30, 40: fluorescent light, 32, 42: color CCD camera, S: coated steel plate, R: red, G: green, B: blue.

Continuation of the front page (72) Inventor Tadatoshi Nakayama 3-15-3 Tokaigami, Settsu-shi, Osaka Asahi Sokki Co., Ltd. (56) References JP-A-63-238540 (JP, A) JP-A-48-101983 (JP, A) JP-A-59-208446 (JP, A) JP-A-52-49856 (JP, A) JP-A-52-11086 (JP, A) JP-A-60-228943 (JP, A) Kaihei 1-67883 (JP, U)

Claims (2)

(57) [Claims] 1. A method for detecting reflected light from a surface of an object to be inspected by a plurality of color sensors sensitive to a plurality of different wavelength ranges, and detecting surface flaws based on output signals from the sensors for each wavelength range. In addition, a surface flaw inspection method that performs arithmetic processing between output signals of these different wavelength ranges, detects surface flaws based on the calculation results, and determines the flaw type based on the detection results of each of these surface flaws. When detecting a surface flaw by the color sensor, the surface of the object to be inspected is placed in close proximity to the surface, and a white light reflecting plate for providing light condensing property to the surface is disposed in the vicinity. Along with irradiating with the rod-shaped light source, as the color sensor, an offset is provided between the reflection position where the optical axis intersects and the irradiation position of the maximum illuminance by the rod-shaped light source on the surface of the inspection object. Was done Surface defect inspection method, characterized by using a dimension color CCD camera. 2. The method according to claim 1, wherein the reflected light from the surface of the inspection object is received by a plurality of color sensors sensitive to each of a plurality of different wavelength ranges, and surface flaws are detected based on output signals from the sensors for each of the wavelength ranges. At the same time, arithmetic processing is performed between the output signals of these different wavelength ranges, a surface flaw is detected based on the arithmetic result, and the intensity of light reflected from the surface of the inspection object is further detected. A surface flaw inspection method for detecting a surface flaw based on the surface flaw and determining a flaw type based on a detection result of each of these surface flaws. Irradiating with a white rod-shaped light source disposed in the vicinity of the surface and providing a light condensing property to the surface in the vicinity thereof, and as a color sensor, on a surface of the inspection object. Optical axes intersect at A surface defect inspection method using a one-dimensional color CCD camera arranged with an offset between a reflection position to be reflected and an irradiation position of the maximum illuminance by the rod-shaped light source.