JP4630945B1 - Defect inspection equipment - Google Patents

Abstract

A defect inspection apparatus capable of detecting defects on the surface of a member having fine irregularities on the surface.
An apparatus for inspecting defects on the surface of an inspection target S, a light projecting means 10 for irradiating the inspection target S with light, and a light receiving unit for receiving light reflected on the surface of the inspection target S The light projecting means 10 is provided between the light source 11 having a plurality of light emitters 13 arranged in a line, and the light source 11 and the inspection target S. A light shielding member 15 that restricts light emitted from each light emitter 13 to the object S to be inspected is provided. The light shield member 15 is a direction in which the light emitters 13 are arranged in the light emitted from each light emitter 13. Are provided with a plurality of blocking portions 15a capable of blocking light inside a certain range from the optical axis of each light emitter 13.
[Selection] Figure 1

Description

  The present invention relates to a defect inspection apparatus. More specifically, the present invention relates to a defect inspection apparatus that inspects the surface of an inspection object using an optical technique.

  In an inspection target having a smooth surface, inspection using an optical method is performed for inspection of defects on the surface, for example, streak-like scratches. In such an inspection, light emitted from a light source such as an LED is irradiated on the surface of the object to be inspected, and reflected light on the surface is imaged by an imaging means such as a camera. Then, an image composed of a signal corresponding to the intensity of the light incident on the photographing means is obtained, and the presence / absence of a defect is determined based on the signal intensity of the photographed image, that is, the image level.

Specifically, the LED light source is arranged so that the angle between the optical axis and the surface of the inspection target is an angle smaller than 60 °, for example. Then, the imaging means is arranged so that its optical axis is orthogonal to the surface of the object to be inspected. That is, when there is no defect on the surface of the object to be inspected, it is arranged so that the light reflected by this surface does not enter the imaging means. In other words, the imaging means is arranged so that only the scattered light that is irregularly reflected on the surface of the inspection object enters the light emitted from the LED light source.
Then, since the surface of the inspection object is a smooth surface, irregular reflection on the surface of the inspection object occurs only when a defect exists on the surface. That is, on the surface of the object to be inspected, scattered light due to irregular reflection is generated only when there is a defect on the surface, so the presence or absence of defects such as scratches is determined based on the intensity of the scattered light imaged by the imaging means. be able to.

By the way, if the intensity of scattered light due to scratches is weak, it is difficult to accurately determine the presence or absence of defects such as scratches even if the scattered light is imaged by the imaging means.
Since the light emitted from the LED light source is highly directional, the intensity of the scattered light due to the flaw depends on the relative arrangement of the optical axis direction of the LED light source and the flaw direction. For example, when the direction of the scratch is perpendicular to or close to the optical axis direction of the LED light source, the intensity of scattered light due to the scratch is increased. On the other hand, when the extending direction of the scratch is parallel to or close to the optical axis direction of the LED light source, the intensity of the scattered light due to the scratch becomes weak.
Then, when the extending direction of the scratch is parallel to or close to the optical axis direction of the LED light source, the intensity of the scattered light to be photographed becomes weak and the signal intensity at the scratched portion becomes small. May not be detected.

As a technique for solving the above-described problems, a technique for irradiating light to the inspection object from directions intersecting each other has been developed (Patent Document 1).
In Patent Document 1, a plurality of light emitting diode arrays each having a plurality of light emitting diodes arranged linearly so that their optical axes are parallel to each other are arranged in a plurality of stages, and the direction of the optical axis of the light emitting diodes is the light emitting diode array. A technique for performing the above-described defect inspection using a light source that is different for each body is disclosed.
In Patent Document 1, if the light source is used, the defect can be irradiated with light from a direction that is not parallel to the extending direction with respect to the defect. It is described that even if there is a defect, a defect such as a flaw can be detected with high accuracy and a good defect inspection can be performed.

However, the technique of Patent Document 1 can detect a surface defect if the surface to be inspected is smooth. In other words, if there is no defect on the surface to be inspected, and light is not diffusely reflected on the surface to be inspected, the intensity of the light imaged between the defect-free part and the defective part Since the difference becomes large, a surface defect can be detected based on the captured image.
However, for a surface having fine irregularities such as a metal surface with a hairline finish, irregular reflection of the irradiated light occurs even with the irregularities, so that the irregularities and the surface defects cannot be identified.

In order to suppress the signal of the light reflected by the surface irregularities on the metal surface that has such a hairline finish, that is, to reduce the intensity of the scattered light reflected by the surface irregularities, the specular reflection type optical system using a diffusion plate Inspection by system is performed.
However, not only the intensity of the scattered light reflected on the surface irregularities, but also the intensity of the scattered light at the defect is weakened. As a result, the difference between the signal of the concavo-convex part and the signal of the defective part becomes small in the photographed image, and there is a problem that a signal with a small defect cannot be recognized.

  At present, there is no inspection apparatus capable of inspecting a metal surface or a textured skin having a hairline finish using an optical method, and such an inspection apparatus is required.

JP 2009-139275 A

  In view of the above circumstances, an object of the present invention is to provide a defect inspection apparatus that can detect defects on the surface of a member having fine irregularities on the surface.

A defect inspection apparatus according to a first aspect of the present invention is an apparatus for inspecting defects on the surface of an object to be inspected, and receives light reflected from the surface of the object to be inspected and a light projecting means for irradiating the object to be inspected with light. The light projecting means is provided between the light source having a plurality of light emitters arranged in a line on a straight line, and the light source and the object to be inspected. A light shielding member that restricts the light emitted from each light emitter to the object to be inspected, and the light shielding member is a direction in which the light emitters are arranged in the light emitted from each light emitter. And a plurality of blocking portions capable of blocking light inside a certain range from the optical axis of each light emitter.
The defect inspection apparatus according to a second aspect of the present invention is the defect inspection apparatus according to the first aspect, wherein the light shielding member is provided so as to be movable along a direction in which the plurality of light emitters are arranged.
The defect inspection apparatus according to a third aspect of the present invention is the defect inspection apparatus according to the first or second aspect, wherein the light shielding member is a plate-like member having a plurality of through holes extending along a direction in which the plurality of light emitters are arranged. The plurality of through holes are arranged along a direction in which the plurality of light emitters are arranged, and portions positioned between adjacent through holes are formed to be the plurality of blocking portions. .

According to the first invention, from the plurality of light emitters located on the same row, only the light outside the predetermined range from the optical axis of each light emitter is irradiated on the surface of the subject to be inspected. Can be irradiated with light from different directions. Then, since it is possible to shine uneven defects deeper than uniform unevenness, even if the surface of the object to be inspected is a surface having fine unevenness such as hairline or satin skin, it detects a scratch on the surface. be able to.
According to the second invention, the range of light blocked by the blocking portion can be changed by moving the light blocking member. Then, it is also possible to irradiate light from the same direction from all the light emitters. In this way, the irradiation state of light can be made optimal in accordance with the state of the surface of the object to be inspected, so that the inspection accuracy can be increased.
According to the third aspect of the present invention, since the through-hole is only formed in the plate-like member, the structure of the light shielding member can be simplified.

It is a schematic explanatory drawing of the cross section parallel to the axial direction of the light projection means 10 in the defect inspection apparatus 1 of this embodiment, (A) is a schematic explanatory drawing of the light projection means 10, (B) is a to-be-measured object. It is a schematic explanatory drawing of the vicinity. It is a schematic explanatory drawing of the cross section orthogonal to the axial direction of the light projection means 10 in the defect inspection apparatus 1 of this embodiment. In the light projection means 10 in the defect inspection apparatus 1 of this embodiment, it is the figure explaining the relationship between the position of the light shielding member 20, and the emitted light radiated | emitted from the light projection means 10. FIG. It is a schematic explanatory drawing of the defect inspection apparatus 1 of this embodiment. It is an experimental result of an Example.

The defect inspection apparatus of the present invention is a defect inspection apparatus that inspects the surface of an object to be inspected using an optical technique, and can detect scratches and the like formed on the surface.
In particular, it is an apparatus suitable for detecting a scratch or the like generated on a surface having regular fine irregularities such as a hairline, or a surface having fine irregularities such as a textured skin.

(Description of defect inspection apparatus 1)
The defect inspection apparatus of the present invention is characterized by the light projecting means for irradiating light onto the surface of the inspection object. First, the overall configuration of the defect inspection apparatus will be briefly described.

In FIG. 4, symbol S indicates an object to be inspected to be inspected for a surface defect (such as a streak) by the defect inspection apparatus 1 of the present invention. The inspection target S is a sheet-like member made of a film, metal, or the like that is continuously conveyed, but is not particularly limited.
As shown in FIG. 4, the defect inspection apparatus 1 of the present invention includes a light projecting unit 10 that irradiates light onto the surface of the inspection target S on the surface side of the inspection target S, and this light projection. An imaging means comprising a light receiving unit that receives light (hereinafter referred to as reflected light) reflected from the surface of the inspection target S by light (hereinafter referred to as irradiation light) irradiated from the means 10 onto the surface of the inspection target S. 20 and an analysis means (not shown) for judging the presence or absence of a flaw or the like based on a signal photographed by the light receiving unit of the photographing means 20.

And if the imaging | photography means 20 has the smooth surface of the to-be-inspected object S, the reflected light (regular reflection light) reflected by the same angle as incident light will inject into the light-receiving part of the imaging | photography means 20 directly. It is arranged so that there is no. In other words, if the surface of the inspection target S is a smooth surface, when the surface of the inspection target S has a scratch or the like and the irradiated light is irregularly reflected by the scratch or the like, only the scattered light is transmitted to the imaging means 20. The photographing means 20 is arranged so as to be incident.
For example, as shown in FIG. 4, the angle θ1 formed by the optical axis 20a of the imaging means 20 and the normal direction of the surface of the object S to be inspected, and the surface of the optical axis 10a of the light projecting means 10 and the surface of the object S to be inspected. If the difference between the angle θ2 and the normal direction is 10 degrees or more, the above state can be obtained.

  The light receiving unit 21 of the imaging unit 20 described above is an imaging device such as a line sensor or a CCD area camera, but is not particularly limited as long as it is a device capable of detecting the scattered light as described above.

(Light projection means 10)
Next, the light projecting means 10 will be described.
In FIG. 1 and FIG. 2, the code | symbol 10a has shown the case of the light projection means 10. FIG. The case 10a is a hollow member that extends along the width direction of the inspection target S (the left-right direction in FIG. 1 and the direction perpendicular to the paper surface in FIG. 2).
As shown in FIG. 2, light is transmitted through one end of the case 10a, specifically, the end (the lower end in FIG. 2) of the case 10a that is arranged to face the object S to be inspected. A light emission window 11c is formed.
The light emission window 11c is formed of a member that transmits light (such as glass or a transparent acrylic plate), but is not particularly limited as long as it is formed of a member that transmits light. Further, instead of the light emission window 11c, a through hole that communicates the inside of the case 10a with the outside may be provided.

  As shown in FIGS. 1 and 2, a light source 11 that emits light toward a light emission window 11c is provided in the case 10a. The light source 11 includes a substrate 12 extending along the axial direction of the case 10 a, that is, the width direction of the inspection target S, and a plurality of light emitters 13 are provided on the substrate 12. Specifically, the plurality of light emitters 13 are arranged in a line along the axial direction of the substrate 12 (the width direction of the object S to be inspected), and are arranged at regular intervals. And as this light-emitting body 13 leaves | separates from the light-emitting body 13, the range irradiated with the light to radiate | emit (henceforth radiated light) spreads (refer FIG. 1).

The light emitter 13 may be, for example, an LED, but is not particularly limited as long as it can emit light within a certain angle range around the optical axis 13a.
In addition, the range in which the light emitter 13 emits light is not particularly limited, but light having an illuminance necessary for inspection can be emitted in an angle range of about 100 to 140 degrees with respect to the optical axis 13a (θ3 in FIG. 1). Those are preferred.

As shown in FIG. 2, a cylindrical lens 14 is provided between the light source 11 and the light emission window 11c. The lens 14 is arranged so that its axial direction is parallel to the width direction of the inspection object S.
The lens 14 is provided to make light emitted from the light emitter 13 parallel light. Specifically, the lens 14 parallels the radiated light emitted from the light emitter 13 in a direction orthogonal to the width direction of the inspection target S (that is, the conveyance direction of the inspection target S, the left-right direction in FIG. 2). It is provided so that it can be light.
That is, in the direction orthogonal to the width direction of the inspection target S, the radiated light emitted from the light emitter 13 can be focused by the lens 14 so as to become parallel light. It is possible to increase the intensity of the light applied to.

  A light shielding member 15 is provided between the light source 11 and the lens 13. The light shielding member 15 is a plate-like member extending along the width direction of the inspection target S. The light shielding member 15 is provided with a plurality of through holes 15 h along the axial direction of the substrate 12. The through holes 15h are formed so as to be positioned between the optical axes 13a of the light emitters 13, and a part of the radiated light emitted from the light emitters 13 passes through the through holes 15h to the inspection object S. It is configured to be irradiated.

In the light shielding member 15 in which the through hole 15h is formed as described above, a portion (blocking portion 15a) located between the adjacent through holes 15h is located on the optical axis 13a of each light emitter 13. Then, in the axial direction of the substrate 12, emitted light inside a certain range from the optical axis of each light emitter 13 is blocked by the blocking unit 15 a and is not irradiated to the inspection target S. In other words, only the radiated light outside the certain range from the optical axis 13a of the light emitted from each light emitter 13 is irradiated to the surface of the inspection object S through the through hole 15h. Then, the illuminator 13 can radiate the emitted light so that the range of the emitted light increases as the distance from the illuminant 13 increases, so that the irradiation light that has passed through the through-hole 15h is the surface of the object S to be inspected. Is irradiated obliquely.
Moreover, since the emitted light of each light emitter 13 is emitted from the through hole 15h sandwiching the blocking portion 15a located on the optical axis 13a, the light emitted from one light emitter 13 to the object S to be inspected is reversed. Irradiated light (corresponding to irradiation light irradiated from the right (light beams 1 to 5) and irradiation light irradiated to the left (light beams a to e) in FIG. 1B). The surface of the inspection object S is irradiated.

Since it is the above structure, in the defect inspection apparatus 1 of this embodiment, since the emitted light can be radiated | emitted to the to-be-inspected object S from the several light-emitting body 13 located on the same row | line | column, The same region can be irradiated with light simultaneously from different directions. That is, in the inspection area of the inspection object S, the light emitter 13 located on the right side of the certain part emits light from the right side to the part, and the light emitter 13 located on the left side of the certain part The portion is irradiated with light from the left side.
In addition, if a certain distance from the light emitter 13 to the inspection object S is separated to some extent, each part of the inspection region in the inspection object S includes a plurality of light emitters 13 (for example, several to dozens). Light is irradiated.

  Then, no matter what direction the scratches are formed on the surface of the inspection object S, the direction of any irradiation light crosses the axial direction of the scratches, so that irregular reflection due to the scratches may occur. it can. Therefore, the accuracy of detecting a scratch formed on the surface of the inspection object S can be increased.

  Moreover, since the configuration as described above is adopted, if the object to be inspected S has irregularities (for example, uniform irregularities) formed on the surface, the intensity of scattered light on the irregularities formed on the surface is determined. In addition, the intensity of scattered light at a surface defect (for example, a deep irregularity defect) can be increased (lighted). Therefore, even if the surface of the object S to be inspected is a surface having fine irregularities such as a hairline or a satin skin, it is possible to detect a scratch or the like existing on the surface. That is, even if there are fine irregularities that cause irregular reflection in addition to the scratches, scratches on the surface can be detected.

The light shielding member 15 is not particularly limited as long as it has a plurality of blocking portions 15a having the above functions. However, as described above, if the light shielding member 15 having a plate-like member with the through holes 15h is adopted, the structure of the light shielding member 15 can be simplified.
Further, the irradiation light applied to the inspection target S through the through-hole 15h can be obtained when the distance from the light emitter 13 to the inspection target S is sufficiently large (for example, 100 mm or more). As shown in 1 (B), irradiation is performed in a state that can be regarded as almost parallel light. The distance from the light emitter 13 to the inspection target S does not necessarily have to be separated until the irradiation light irradiated on the inspection target S becomes parallel light. However, when the irradiation light applied to the inspection target S is substantially parallel light (that is, when the distance from the light emitter 13 to the inspection target S is sufficiently large), unevenness in the amount of light is generated. This is preferable because the detection sensitivity can be stabilized.

With respect to the relationship between the plurality of light emitters 13 and the blocking portions 15a and the through holes 15h of the light shielding member 15, the values in the following FIGS. 1, 2, and 4 are preferably in the following ranges.
Distance H1 from illuminant 13 to surface S to be inspected H1: 100 to 200 mm
Distance H2 from the light receiving portion of the imaging means 20 to the surface of the inspection object S2: 500 to 1000 mm
Distance H3 from light emitter 13 to light shielding member 15: 3 to 5 mm
Angle θ2 between the optical axis 20a of the imaging means 20 and the normal direction of the surface of the inspection object S1: 30 to 40 degrees Angle θ2 between the optical axis 10a of the light projection means 10 and the normal direction of the surface of the inspection object S : 40 to 60 degrees The range in which the emitted light of the illuminant 13 emits light with an effective illuminance θ3: 100 to 140 degrees Interval L1 between adjacent illuminators 13: 10 to 30 mm
Length L2 of the light shielding part 15a in the light shielding member 15: 5 to 15 mm

(Moving structure)
If the defect inspection apparatus 1 of the present embodiment is to inspect only the inspection target S having a surface with fine irregularities such as a hairline or a satin surface, the irradiation light irradiated on the inspection target S is always What is necessary is just to provide the light-shielding member 15 so that it may be in the state mentioned above.

  However, if the defect inspection apparatus 1 according to the present embodiment can inspect other inspection targets S, the light shielding member 15 can be moved along the axial direction (that is, the axial direction of the substrate 12). It is preferable to provide the case 10a. That is, it is preferable that the relative positions of the light blocking members 15a and the through holes 15h and the light emitters 13 in the axial direction of the substrate 12 can be changed.

  With such a configuration, the range of light blocked by the blocking portion 15a can be changed by moving the light blocking member 15, so the direction of the irradiation light irradiated from the respective light emitters 13 to the inspection target S In addition, the region where the irradiation light is irradiated can be changed. Then, according to the surface state of the inspection target S, the state of the irradiation light irradiated to the inspection target S can be optimized, so that the inspection accuracy of defects such as scratches can be increased. .

  For example, if the defect inspection apparatus 1 according to the present embodiment is used to inspect irregularities formed on a surface having scattering properties (for example, paper), all in the width direction of the inspection target S. It is preferable that the irradiation light from the light emitter 13 is irradiated from the same oblique direction with respect to the inspection object S. Then, even if the surface of the inspection object S has a scattering property, the influence of the surface scattering can be suppressed, so that the inspection of the concavo-convex defect or the like can be accurately performed (see FIG. 3A). .

  Further, in the case of inspecting a material to be inspected with a small amount of reflected light by the defect inspection apparatus 1 according to the present embodiment, irradiation light from all the light emitters 13 is inspected in the width direction of the inspection target S. It is preferable to irradiate so as to be orthogonal to the object S. Then, the crack etc. which are formed in the surface of to-be-inspected object S can be test | inspected correctly (refer FIG. 3 (B)).

In order to enable all the above states, the relationship between the plurality of light emitters 13 and the through-holes 15h of the light shielding member 15 is that each value in the following FIG. 1, FIG. 2 and FIG. If it is.
Distance H1 from illuminant 13 to surface S to be inspected H1: 100 to 200 mm
Distance H2 from the light receiving portion of the imaging means 20 to the surface of the inspection object S2: 500 to 1000 mm
Distance H3 from light emitter 13 to light shielding member 15: 3 to 5 mm
Angle θ2 between the optical axis 20a of the imaging means 20 and the normal direction of the surface of the inspection object S1: 30 to 40 degrees Angle θ2 between the optical axis 10a of the light projection means 10 and the normal direction of the surface of the inspection object S : 40 to 60 degrees The range in which the emitted light of the illuminant 13 emits light with an effective illuminance θ3: 100 to 140 degrees Interval L1 between adjacent illuminators 13: 10 to 30 mm
Length L2 of the light shielding part 15a in the light shielding member 15: 5 to 15 mm

(Experimental result)
In order to confirm the effect of the defect inspection apparatus of the present invention, surface inspection was performed on a member having irregularities on the surface when the light shielding member was provided (Example) and when the light shielding member was not provided (Comparative Example).
In the experiment, the aluminum foil was bent on the back surface (the poor surface) of the aluminum foil to form streak-like wrinkles, and it was confirmed whether or not the wrinkles could be detected.

The apparatus used for the experiment was the same as that of the example and the comparative example, except that the light shielding member was provided in the apparatus of the example.
In addition, each numerical value in the used apparatus and FIG.1, FIG.2 and FIG.4 is as follows.
(1) Used apparatus photographing means: linear CCD camera (Part No. 4020: made by Hugh Tech)
Luminescent body: LED light source (product number LEDB1: manufactured by FUTECH)
(2) Distance H1: 60 mm from each numerical light emitter to the surface to be inspected
Distance from the light receiving part of the imaging means to the surface to be inspected H2: 463 mm
Distance from light emitter to light shielding member H3: 4 mm
Angle θ1 formed by the optical axis of the imaging means and the surface to be inspected 1: 30 ° Angle formed by the optical axis of the light projecting means and the surface of the object to be inspected θ2: 55 ° Range in which the emitted light of the light emitter emits light with an effective illuminance θ3: 120 ° between adjacent light emitters L1: 20 mm
The length L2 of the light shielding part in the light shielding member: 6.8 mm

The experimental results are shown in FIG. Note that the position of X in FIG. 5 corresponds to the portion where the streak is present.
First, as shown in FIG. 5 (A), the signal intensity as a whole is large in the comparative example, and the change in the intensity is also large. For this reason, the signal caused by the scattered light at the wrinkle position is buried in the signal caused by the scattered light in other portions, and the presence or absence of wrinkles could not be detected. On the other hand, as shown in FIG. As described above, in the embodiment, the signal intensity is reduced as a whole, and the change in the intensity is also reduced. However, the signal intensity at the wrinkle position is stronger than the signals at other portions, and it was confirmed that wrinkles exist at that position.
That is, in the apparatus of the embodiment, even if there are fine irregularities on the surface to be inspected, the intensity of scattered light from defects such as wrinkles can be made stronger than the intensity of scattered light in other parts, and defects such as wrinkles It can be confirmed that the defect can be detected.

  From the above results, it can be confirmed that the defect inspection apparatus of the present invention is effective for surface inspection of a member having fine irregularities on the surface.

  The defect inspection apparatus of the present invention is suitable for surface inspection of a member having a textured surface, a hairline or the like having fine irregularities on the surface.

DESCRIPTION OF SYMBOLS 1 Defect inspection apparatus 10 Light projection means 11 Light source 13 Light-emitting body 15 Light-shielding member 15h Through-hole 20 Imaging means 21 Light-receiving part S Inspection object

Claims (3)

A device for inspecting a surface defect to be inspected,
A light projecting means for irradiating the test object with light;
Comprising a light-receiving unit that receives light reflected from the surface of the object to be inspected,
The light projecting means is
A light source having a plurality of light emitters arranged in a line on a straight line;
A light-shielding member that is provided between the light source and the inspection target and restricts light emitted from each light emitter to the inspection target;
The light shielding member is
Among the light emitted from each light emitter, a plurality of blocking portions that can block light inside a certain range from the optical axis of each light emitter in the direction in which the light emitters are arranged are provided. A feature defect inspection device. The shading member is
The defect inspection apparatus according to claim 1, wherein the defect inspection apparatus is provided so as to be movable along a direction in which the plurality of light emitters are arranged. The shading member is
A plate-like member having a plurality of through-holes extending along a direction in which the plurality of light emitters are arranged;
The plurality of through holes are:
3. The device according to claim 1, wherein the plurality of light emitters are arranged along a direction in which the light emitters are arranged, and a portion located between adjacent through holes is formed to be the plurality of blocking portions. Defect inspection equipment.