JP2002005845A - Defect inspecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a defect-inspecting apparatus which can fully detect even defects such as finerly uneven flaws that could not be detected fully so far by the conventional surface defect inspecting apparatus. SOLUTION: The defect inspecting apparatus is provided with a lighting device for lighting a specimen, an image pickup device for receiving light reflected from an object to be inspected and an image processor, which processes an output signal of the image pickup device to detect a defect of the specimen. The direction of photo detection at the image pickup device and the direction of irradiation at the lighting device are on the same side, with respect to the normal of the object.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to aluminum,
The present invention relates to a defect inspection device that detects a defect such as a fine flaw existing on the surface of a sheet-like object such as a steel plate, a diffusion film, and a resin plate.

[0002]

2. Description of the Related Art As a general method for detecting a surface defect, there are known two types of optical systems, a regular reflection optical system and a scattering reflection optical system. FIG. 6 is a configuration diagram illustrating a method of a surface flaw inspection apparatus using a regular reflection optical system. The regular reflection optical system is disclosed in, for example, JP-A-07-349721.
Suitable for detecting dents in sheet-like objects. That is, the regular reflection optical system is effective for detecting uneven surface flaws.

FIG. 7 is a configuration diagram illustrating a surface flaw inspection apparatus using a scattering reflection optical system. The scattering reflection optical system is disclosed in, for example, Japanese Patent Application Laid-Open No. 02-137101, and is effective for detecting colored foreign matters and dirt defects on the surface. FIG.
In, the radiated light from the illumination device 3 is applied to the inspection object 1. The light reflected by the inspection object 1 has a specular reflection component 4
And a scattering component 5. The imaging device 2 receives the combined light of the specular reflection component 4 and the scattering component 5.

[0004]

However, in both the regular reflection optical system shown in FIG. 6 and the scattering reflection optical system shown in FIG. 7, the light receiving direction of the image pickup device is such that the regular reflection light out of the reflection light from the inspection object is reflected. In this case, it is often impossible to sufficiently detect fine flaws or the like existing on the surface of an aluminum plate or the like having a formation. The reason for this is that the S /
This is because N (Signal to Noise Ratio) is small, and the signal light of the flaw defect is buried in the light quantity of the formation. For this reason, the conventional surface defect inspection apparatus has a problem in that it is not possible to detect fine unevenness flaws on an object having formation.

The present invention solves the above-mentioned problems, and
An object of the present invention is to provide a defect inspection apparatus capable of sufficiently detecting defects such as fine irregularities and flaws that cannot be sufficiently detected by a conventional surface defect inspection apparatus.

[0006]

According to the present invention, there is provided a defect inspection apparatus which illuminates an object to be inspected.
An image pickup apparatus that receives reflected light from an object to be inspected, and a defect inspection apparatus including an image processing apparatus that processes an output signal of the image pickup apparatus to detect a defect of the object to be inspected, The light receiving direction and the irradiation direction of the illumination device are on the same side with respect to the normal direction of the inspection object.

In the apparatus configured as described above, the light receiving direction of the imaging device and the irradiation direction of the illuminating device are arranged obliquely on the same side with respect to the normal direction of the object to be inspected. The amount of reflected light at a certain formation is missed as a specular reflection component, and a fine defect having shallow unevenness is received as a scattering component by an imaging device. Thereby, the defect inspection apparatus of the present invention can detect a fine defect.

Preferably, the angle between the light receiving direction of the imaging device and the normal direction of the inspection object is larger than the angle between the irradiation direction of the illumination device and the normal direction of the inspection object. When the object to be inspected is a sheet-like object having a formation, it is preferable that only the defective portion is emphasized and detected as a bright defect. Further, when the object to be inspected is a mirror-like sheet-like object, it is preferable to detect a defect on a normal mirror surface as a dark defect. Further, it is preferable to provide a second imaging device in which the light receiving direction of the second imaging device and the irradiation direction of the illumination device 3 are located substantially symmetrically with respect to the normal direction of the inspection object 1.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration block diagram illustrating an embodiment of the present invention. In the figure, reference numeral 1 denotes an inspection object, 2 denotes an imaging device, 3 denotes an illumination device, and 6 denotes an image processing device.

The imaging device 2 detects reflected light from the inspection object 1, converts the detection result into an analog video signal, and outputs the analog video signal to the image processing device 6. The imaging device 2 is arranged in the width direction of the inspection object 1 (in the moving direction,
The light in the range to be inspected (at right angles) is sequentially received. The imaging device 2 is not particularly limited, but when the inspection object 1 is a sheet-shaped object having a width, for example, a line CCD camera is preferably used. Also,
The resolution of the imaging device 2 can be appropriately determined according to the type of the object to be inspected or the detected defect. For example, the resolution in the width direction is about 0.25 mm / pixel, and the resolution in the running direction is about 0.25 mm / pixel. It can be.

The illumination device 3 is an illumination device for irradiating the inspection object 1 with light. In the present invention, the illumination device 3 is not particularly limited, and rod illumination such as a fluorescent lamp used in a normal regular reflection system can be used. The illumination device 3 irradiates the inspection object 1 with radiated light from an oblique direction.

In the defect inspection apparatus of the present invention, the positional relationship between the illumination device 3 and the imaging device 2 is important, and the irradiation direction of the illumination device 3 with respect to the normal direction of the inspection object 1 and the imaging device 2 It is necessary to install the lighting device 3 and the imaging device 2 so that the light receiving direction is on the same side. By installing the illuminating device 3 and the imaging device 2 in this manner, the reflected light amount of the formation, which is a normal portion of the inspection object 1, is escaped as a regular reflection component, and a fine defect with a small unevenness is used as a scattering component by the imaging device. Light can be received, and fine unevenness defects such as flaws existing on the surface of the inspection object 1 can be detected. Preferably, the illumination device 3 and the imaging device are arranged such that the angle between the light receiving direction of the imaging device 3 and the normal direction of the inspection object 1 is larger than the angle between the irradiation direction of the illumination device 3 and the normal direction of the inspection object 1. 2 is installed.

The angle (irradiation angle) θ of the irradiation direction of the illumination device 3 with respect to the normal direction of the inspection object 1 is preferably 10 ° to 30 °, and the light receiving direction of the imaging device 3 and the inspection object 1
Is 20 ° to 75 with respect to the normal direction (light receiving angle).
° is preferable. Further, it is preferable that the angle difference between the irradiation angle θ and the light receiving angle と す る is 10 ° to 30 °.
Further, the distance between the inspection object 1 and the lighting device 3 is usually 3
It is set to be about 0 to 100 mm.

In the defect inspection apparatus of the present invention,
The defect inspection may be performed while the inspection object 1 is moved while the imaging device 2 and the illumination device 3 are fixed, or the imaging device 2 and the illumination device 3 having a fixed positional relationship are placed on the inspection object 1. The defect inspection may be performed while moving. Image processing device 6
Inputs an analog video signal output from the imaging device 2 and detects a defect in the inspection object 1 based on inspection conditions defining the width, length, area, and the like of a defective portion.

FIG. 2 is a block diagram of an illumination system of a defect inspection apparatus according to another embodiment of the present invention. In the present embodiment, the imaging device 2 for fine unevenness defects is used as the imaging device 2.
2 and an imaging device 24 for a normal unevenness defect. Similar to the first embodiment, the imaging device 22 for fine unevenness is provided so that the light receiving direction is on the same side as the irradiation direction of the illumination device 3 with respect to the normal direction of the inspection object 1. I have. Normally, the imaging device 24 for unevenness defects is provided on the opposite side where the light receiving direction is substantially symmetric with the irradiation direction of the illumination device 3 with respect to the normal direction of the inspection object 1. The imaging device 22 for fine irregularities does not receive the regular reflection component 4 of the normal portion among the reflected light beams of the irradiation light emitted from the illumination device 3 reflected on the surface of the inspection object 1 and scatters the defect portion. Only the component 5 is received. On the other hand, the imaging device 24 for a normal concave / convex defect mainly receives the regular reflection component 4 of the normal part among the reflected light beams emitted from the illumination device 3 and reflected on the surface of the inspection object 1.

By providing the imaging device 24 for a normal unevenness defect in this way, a defect which can be detected only by the imaging device 22 for a fine unevenness defect and the imaging device 24 for a normal unevenness defect and the imaging device 22 for a fine unevenness defect are both provided. Detectable defects can be distinguished, and detected defects can be classified.

FIG. 3 is an output waveform diagram of the image pickup apparatus for a normal unevenness defect in regular reflection illumination. In the imaging device 24 for irregularities and defects, the reflected light beam, which is emitted from the illumination device 3 and is reflected on the surface of the inspection object 1, is used as the combined light of the regular reflection component 4 of the normal part and the scattering component 5 of the defective part. Receiving light. For this reason, even if the surface of the inspection object 1 has a shallow flaw,
The scattering component from the flaw is buried in the synthetic light.

FIG. 4 is an output waveform diagram of the imaging device for minute unevenness defects. The imaging device 22 for minute unevenness defect does not receive the regular reflection component 4 of the normal part among the reflected light beams emitted from the illumination device 3 and reflected on the surface of the inspection object 1,
Only the scattering component 5 of the defect is received. For this reason, even if there is a shallow fine defect on the surface of the inspection object 1, it can be reliably detected.

FIG. 5 is a structural block diagram for explaining details of the image processing apparatus. The image processing device 6 includes an A / D conversion circuit 61, a run-length encoding circuit 62, and a connectivity determination circuit 63. The A / D conversion circuit 61 receives the analog video signal output from the imaging device 2 and
For example, it is converted into an 8-bit digital signal (0 to 255).
The run-length encoding circuit 62 binarizes the digital signal sent from the A / D conversion circuit 61 using a preset threshold value, and performs run-length encoding. The connectivity processing determination circuit 63 performs the connectivity processing determination on the run-length encoding, thereby determining the size of the defect to be detected, that is, the inspection condition that defines the width, length, area, and the like of the defective portion. Based on this, a defect of the inspection object 1 is detected.

In the above embodiment, the case where a fine defect of the object to be inspected is detected as a defect brighter than the reflected light amount of the reference value has been described. However, the present invention is not limited to this. In the case of a mirror-like film, it may be configured to detect as a dark defect contrary to formation. Further, the defect inspection apparatus of the present invention is particularly suitable as an inspection apparatus for a flaw defect of fine unevenness having a small depth existing on the surface of a sheet-like material such as an aluminum plate.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As an embodiment, an example in which the present invention is used as a surface defect inspection apparatus for an aluminum plate having a width of 1900 mm will be described in detail.

2 using a 100 W halogen lamp as a light source
The illumination device 2 using the 000 mm rod illumination is placed at a position 15 mm from the surface of the aluminum plate so that its illumination direction is inclined by 10 ° from the normal direction of the aluminum plate as the inspection object to the moving direction of the aluminum plate. The aluminum plate was set so as to be perpendicular to the moving direction. A CCD camera (SCD-5000A manufactured by Mitsubishi Rayon Co.) using a lens having a resolution of 0.23 / pixel × 0.5 mm / scan, f = 35 mm, and an F value of 2.0 as the imaging device 3.
Were placed at a distance of 990 mm from the surface of the aluminum plate at a distance of 1100 mm such that the light receiving direction was inclined by 30 ° from the normal direction of the aluminum plate to the moving direction of the aluminum plate. A / D
The image processing device 6 including the conversion circuit 61, the run-length encoding circuit 62, and the connectivity processing determination circuit 63 was connected.

Using the defect inspection apparatus having the above configuration, 11
When a defect inspection of the surface of an aluminum plate running at a speed of 0 m / min was performed, a conventional defect inspection device in which the imaging device 2 and the illumination device 3 were arranged at positions symmetrical with respect to the normal line of the inspection object. In this case, fine irregularities and flaws which could not be detected could be reliably detected.

[0024]

As described above, according to the defect inspection apparatus of the present invention, the light receiving direction of the imaging device and the irradiation direction of the illumination device are set in the normal direction of the inspection object. Since the configuration is such that they are on the same side, it is possible to detect fine defects that could not be detected by the conventional regular reflection optical system, and the level of quality assurance is increased.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram illustrating an embodiment of the present invention.

FIG. 2 is a configuration block diagram of an illumination system of the apparatus of FIG.

FIG. 3 is an output waveform diagram of an imaging device for a normal unevenness defect in regular reflection illumination.

FIG. 4 is an output waveform diagram of the imaging device for minute unevenness defects.

FIG. 5 is a configuration block diagram illustrating details of an image processing apparatus.

FIG. 6 is an explanatory view of a regular reflection optical system as a conventional technique.

FIG. 7 is an explanatory view of a scattering reflection optical system which is a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inspection object 2 Image pick-up device 22 Image pick-up device for fine unevenness defects 24 Image pick-up device for normal unevenness defects 3 Illumination device 4 Specular reflection component of light amount 5 Scattering component of light amount 6 Image processing device

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tadashi Suga 4-1-1 Ushikawa-dori, Toyohashi-shi, Aichi F-term in the Toyohashi Works of Reference Material 2G051 AA32 AA37 AA41 AB07 AC02 BB01 CA03 CA07 CB01 CB05 DA06 EA11 EA12 EB01 5B057 AA01 BA02 BA15 CG04 DA03 DB02 DB09 DC03 DC04 DC30 DC36

Claims (5)

[Claims] An illumination device for illuminating an object to be inspected, an imaging device for receiving reflected light from the object to be inspected, and an image processing for processing an output signal of the imaging device to detect a defect of the object to be inspected A defect inspection device comprising a device, wherein the light receiving direction of the imaging device and the irradiation direction of the illumination device are on the same side with respect to a normal direction of the inspection object. 2. An angle between a light receiving direction of the imaging device and a normal direction of the object to be inspected is larger than an angle between an irradiation direction of the illumination device and a normal direction of the object to be inspected. 2. The defect inspection device according to 1. 3. The defect inspection apparatus according to claim 1, wherein, when the inspection object is a sheet-like material having a formation, the defect is detected as a bright defect in a form in which only a defective portion is emphasized. . 4. The defect according to claim 1, wherein the defect is detected as a dark defect with respect to a normal mirror surface when the inspection object is a mirror-like sheet-like material. Inspection equipment. 5. The apparatus according to claim 1, further comprising a second imaging device in which a light receiving direction of the second imaging device and an irradiation direction of the illumination device are positioned substantially symmetrically with respect to a normal direction of the inspection object. The defect inspection apparatus according to any one of claims 1 to 4, wherein