JPH068790B2 - Surface inspection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a surface inspection device, and in particular to a surface of an object such as an end (bottom surface and upper surface) of a bottle cap, beer can, etc. The present invention relates to a surface inspection device that inspects for the presence or absence of defects.

[Conventional technology]

The cap of the bottle, the end of the beer can, etc. are made of ordinary plastic or metal, and the plane (top or bottom) thereof is circular. Further, in order to sufficiently withstand the pressure fluctuation due to the liquid in the container, in other words, to increase the strength, the cap and the end are provided with a plurality of concentric circles (rings) or spiral irregularities. It is usually formed.

FIG. 7A is a top view of a cap (1) of a metal bottle, which is an example of the object to be inspected, and FIG. 7B shows B- of FIG.
It is sectional drawing along the B line. In the figure, (a), (b) and
(c) is the concentric concavo-convex as described above, and (a) is the cap.
(B) and (c) are ring-shaped protrusions that project upward from the upper surface of (1), and are provided inside the ring-shaped protrusions (a) on the upper surface of the cap (1). The boundaries of the ring-shaped steps are shown respectively.

FIG. 8 is a schematic diagram of an example of a conventional surface inspection apparatus for inspecting the presence or absence of defects such as flaws on the surface of the cap (1) of the bottle to be inspected as shown in FIG. In the figure,
(2) is a light source such as a lamp that illuminates the surface of the cap (1). In this case, since the surface of the cap (1) has unevenness, the light source (2) is
It is located diagonally above the cap (1). (3) is the cap
A photoelectric conversion sensor such as a video camera that receives light from the light source (2) reflected on the surface of (1) and generates a video signal,
It is placed above the cap (1) so that the optical axis of the optical system passes through the center (O) of the cap (1) and is perpendicular to the surface of the cap (1). (4) is an electronic processing device composed of a computer, etc.
The video signal from (3) is analyzed to determine the quality of the surface of the cap (1). Incidentally, FIG. 9 shows the light source (2) of FIG.
FIG. 3 is a plan view showing the relationship between the cap and the cap (1).

Light from the light source (2), which is arranged diagonally above the cap (1), is diffusely reflected by the surface on the cap (1), and a part of this diffusely reflected light is generated by the photoelectric conversion sensor or the video camera (3). ), Which produces a video signal corresponding to the optical image of the surface of the cap (1), which is processed by the electronic processing unit (4) to In comparison with the above, defects such as stains and stains that are unusually dark or unusually bright are detected, and the quality of the surface of the cap (1) is determined.

In this case, as shown in FIG. 9, of the light from the light source (2), the light at the central portion, that is, the light traveling substantially along the optical axis (A), is the surface of the cap (1). Of the ring-shaped protrusion (a) and the boundaries (b) and (c) of the cap (1) with respect to the center (O), portions (a ′) and (b ′) indicated by thick lines on the light source (2) side. ) 、
(c ') and the center (O) of the portion (a') of the ring-shaped protrusion (a)
The part (a ″) on the opposite side is a part that rises like a wall, as is apparent from FIGS. 7B and 8, and these parts (a ′), (b ′), ( Diffuse reflection of light in c ′) and (a ″)
The diffused light significantly more than the diffused reflection in other parts, and the diffused reflected light in these parts is directly incident on the video camera (3). On the other hand, the same ring-shaped protrusion (a) and boundaries (b) and (c)
Most of the light diffusely reflected by the wall-shaped rising portions other than (a ′), (b ′), (c ′) and (a ″) is indicated by an arrow (d) in FIG. 9. The light does not directly enter the video camera (3), but the light that is diffusely reflected by the flat surface of the cap (1) as usual enters the video camera (3) and enters the cap (1). Output as video signal, electronic processing device
The data is input to (4) and processed as described above in this device (4) to determine whether the cap (1) has a defect, that is, whether the cap (1) is good or bad. The arcuate parts (a '), (a "), (b')
The angular range (ARC) of (c ') is smaller than 90 ° about the optical axis (A).

[Problems to be solved by the invention]

As described above, in the conventional device, the diffused reflection of light at the portions (a ′), (b ′), (c ′) and (a ″) on the surface of the cap (1) is significantly larger than that at other portions. Since these diffusely reflected lights are directly incident on the video camera (3), the parts (a ′), (b ′), (c ′) and (a ″) in the video camera (3) are Are significantly brighter than the other parts, and these parts (a '), (b'),
Not only is it impossible to inspect for defects in (c ′) and (a ″), but it also adversely affects the inspection of other parts. Examine the other part excluding the part that causes diffuse reflection, or change the angle of irradiating the surface of the cap (1) of the light from the light source (2) with different parts of the same cap (1) surface. The inspection had to be repeated many times, which was time-consuming and costly.

Therefore, the present invention aims to provide a novel surface inspection apparatus for an object which eliminates the above problems.

[Means for solving problems]

According to the present invention, the light splitting means for splitting light from one light source into two directions and the light reflecting means for irradiating the light in two directions from the light splitting means onto the surface of the object to be inspected obliquely from above. In the device for inspecting the surface of the object to be inspected by imaging the surface of the object to be inspected having the uneven surface irradiated by the light source, and processing the video signal by the electronic processing device,
The light reflected by the light reflecting means in front of the light source is an opaque portion that does not illuminate the surface of the object to be inspected in the lower substantially triangular area centered on the center of the surface of the object to be inspected and in the upper substantially triangular area symmetrical to this. In other areas, an optical mask is provided as a transparent portion that transmits light and irradiates the surface of the object to be inspected, and the light in the two directions is arranged so as to be orthogonal to each other. Irradiation was performed so that the diffuse reflection of light there was substantially uniform.

[Action]

In the present invention, a combination of one light source (2C) having a special optical mask (6C), a half mirror (7A), a mirror (7B), and (7C) is provided on the uneven surface of the inspection object (1). Then, the above surface is irradiated so that the diffused reflection of light on the surface is substantially uniform, the diffused reflected light is received by the video camera (3), and the video signal from it is received by the electronic processing device (4). After processing, the presence or absence of defects on the surface of the inspection object (1) is inspected.

〔Example〕

An embodiment of the present invention will be described below with reference to the first and second embodiments. Incidentally, in the example of the present invention shown in FIG. 1, a photoelectric conversion sensor (video camera) (3) and an electronic processing device (4)
Is the same as the conventional example shown in FIG. 8, and the arrangement of the video camera (3) with respect to the cuff (1), which is an example of the object to be inspected, is almost the same as the example shown in FIG. , They are not shown in FIG. 1 for simplicity. That is, FIG. 1 shows only the main part of the present invention.

In FIG. 1, (2A) and (2B) are light sources that irradiate the surface of the cap (1) with light obliquely from above, and in this example, their optical axes (5A) and (5B). Are arranged diagonally above the cap (1) so that they intersect at the center (O). or,
(6A) and (6B) are optical masks arranged in front of the light projection surfaces of the light sources (2A) and (2B), respectively.

Assuming that the optical mask (6A) is not present, the light from the light source (2A) will be emitted from the cap as described in FIGS. 8 and 9.
The angular range (ARC) of the ring-shaped protrusion (a) on the surface of (1) is
Arc-shaped parts (a ′), (a ″) smaller than 90 °, boundary
In parts (b ') and (c') of (b) and (c), they are significantly diffused compared to other parts, and are directly incident on the video camera (3), which causes inspection failure as described above. . Therefore, in the example of the present invention shown in FIG. 1, an optical mask (6A) is provided in front of the light projection surface of the light source (2A) so that the light from the light source (2A) is at least partially exposed.
(a '), (a "), (b'), and (c ') are not incident. Of course, the light from the light source (2A) is part (a'), (a"), and (a). It is incident on the surface of the cap (1) other than b ') and (c').

Next, an example of the optical mask (6A) (or (6B)) according to the present invention will be described with reference to the front view of FIG.

The optical mask (6A) shown in FIG. 2 is, for example, a substantially square transparent plate made of glass or the like and has four triangular portions (6A1), (6A2), (6A3), (2A) with two diagonal lines. 6A4) and divide two facing triangular parts, (6A2) and (6A4) in this example,
For example, it is made opaque (shown by diagonal lines in FIG. 2) by using black paint or the like, and (6A1) and (6A3) are transparent parts.

As shown in FIG. 1, the opaque parts (6A2) and (6A4) are arranged in the vertical direction in front of the light projection surface of the light source (2A) and the light of the light source (2A) is placed on the optical mask (6A) as described above. Place it so that it is parallel to the projection surface. In this case, the center (0A) of the optical mask (6A) substantially coincides with the optical axis (5A) of the light source (2A). Therefore,
The light from the light source (2A) is partially blocked by the optical mask (6A), and the surface portions (a ′), (a ″) of the cap (1),
It does not reach at least a substantially drum-shaped portion that includes (b ′) and (c ′) and is substantially symmetrical with respect to the optical axis (5A), and reaches the surface of the cap (1) other than those portions. , Where it is diffusely reflected as usual and is incident on the video camera (3) arranged above the cap (1), and the video signal from it is processed by the electronic processing device (4) and the surface of the cap (1) is processed. The inspection is done. This is exactly the same as the conventional device as described above.

As described above, when the optical mask (6A) is used, the light from the light source (2A) is emitted from the surface portion (a '), (a "), (b') of the cap (1).
Since the drum-shaped portion including (c ') and (c') is not reached, these portions cannot be inspected. Therefore, in the present invention, as shown in FIG. 1, in addition to the combination of the light source (2A) and the optical mask (6A), a similar combination of the light source (2B) and the optical mask (6B) is provided at a predetermined angle from the former. Spacing, that is, arcuate parts (a '), (a ") ...
The angular range (ARC) of at least 1/2 or more, (180 ° -1 /
2ARC) and place the cap (1) in the same position as the former.
Arrange so as to illuminate the surface of. Therefore, due to the combination of the light source (2B) and the optical mask (6B), the light did not reach depending on the combination of the light source (2A) and the optical mask (6A).
The drum-shaped portion including the surface portions (a ′), (a ″), (b ′) and (c ′) of (1) is irradiated. Due to the presence of the optical mask (6B), the light source ( For 2B), the part (a ′) for the light source (2A),
Although the light from the light source (2B) does not reach the surface portion of the cap (1) corresponding to (a ″), (b ′) and (c ′), (these portions are the light source (2A) and It has already been irradiated by the combination of the optical mask (6A)), and reaches the other portions by being superimposed on the light from the light source (2A).

As described above, according to the present invention, only one light source is used, such as the protrusions (a ′), (a ″), (b ′) and (c ′) on the upper surface of the cap (1). The part that makes incident light remarkably diffused compared to other parts and makes surface inspection of the cap (1) impossible.
For (a ′), (a ″), (b ′), and (c ′), an optical mask is used to irradiate light from this light source, but other light sources having an optical mask are used. Since the irradiation is performed, the surface of the cap (1) having the ring-shaped or arc-shaped concavo-convex portion can be easily and reliably inspected in one inspection.

Further, the optical masks (6A) and (6B) do not have to be limited to the patterns shown in FIG. 2, and the point is that light is not applied to the surface portion of the object to be inspected that causes unnecessary diffused reflection at least unnecessarily. For example, as shown in FIG. 3, it may have opaque portions (6a1) and (6a2) indicated by vertically symmetrical squiggle lines with respect to the center (0A) (other portions (6a3) and (6a4) are transparent). ).

FIG. 4 is a top view of a main portion similar to FIG. 1 of another example of the present invention. In this example, as the light sources (2a) and (2B), light sources that emit substantially parallel light are used, and the optical axes (5
A) and (5B) are arranged so as to be substantially orthogonal to each other at the center (O) of the cap (1). Optical masks (6A), (6B)
For example, the arrangement shown in FIG. 2 is arranged in the same manner as in the first example.

According to the example of FIG. 4, the center (O) of the circular surface of the cap (1) and the optical axis (5A) of the light source (2A) are formed by combining the light source (2A) and the optical mask (6A). About 90 symmetrical about
Even though the fan-shaped parts (1A) and (1A ') in the angular range of ° are irradiated, they are symmetrical with respect to the center (O) of the surface of the cap (1) and the optical axis (5B) of the other light source (2B). The remaining fan-shaped parts (1B) and (1B ′) in the angular range of approximately 90 ° are not irradiated. in this case,
Arc-shaped portions (a ′), (b ′) (a ″) and (a ″) that rise up like a wall on the surface of the cap (1) that causes the above-mentioned remarkable diffuse reflection.
Is a fan-shaped part (1B) that is not illuminated by the light source (2A) and
Since they are present respectively in (1B ′), the surface of the cap (1) cannot be inspected. Similarly, by combining the light source (2B) and the optical mask (6B), the light source (2A) and the optical mask
The fan-shaped parts (1B) and (1
Although B ') is illuminated, the remaining fan-shaped portions (1A) and (1A') are not illuminated. Of course, for the combination of the light source (2B) and the optical mask (6B), the portions (a '), (b'), which cause remarkable diffuse reflection,
Since (c ′) and (a ″) are present in the portions (1A ′) and (1A) which are not illuminated by this combination, respectively, they do not cause the surface of the cap (1) to be inspectable.

As described above, according to the example of the present invention shown in FIG. 4, the entire surface of the cap (1) has a combination of the light source (2A) and the optical mask (6A), the light source (2B) and the optical mask (6B). Since the irradiation is performed separately and in other words, the light is uniformly emitted without substantially overlapping, the normal diffuse reflection of incident light on the surface of the cap (1) is almost uniform, and The surface inspection can be performed more accurately.

Now, in the example of the present invention shown in FIGS. 1 and 4, two light sources (2A) and (2B) are used, but the present invention does not use two light sources but one light source from the prior art. This can be done by using some suitable light splitting and reflecting means.

An example thereof will be described below with reference to FIG.

FIG. 5A is a top view of a main part of the example, and FIG. 5B is a perspective view thereof. In this example, for example, the optical mask (6A)
Alternatively, one light source (2C) also having an optical mask (6C) similar to (6B) on its front surface, one light splitting means such as a half mirror (7A) and two light reflecting means, For example mirror (7
B) and (7C), for example, as in the example shown in FIG.
Irradiate the top surface of the cap (1). The light source (2C) emits substantially parallel light.

Hereinafter, this example of the present invention will be described in detail, the light source (2C) is
It is arranged above the cap (1) so that its optical axis (5C) is substantially parallel to the upper surface of the cap (1) and is orthogonal to its central axis (X). The mirror surface (7A1) of the half mirror (7A) is substantially vertical and is on the central axis (X) of the cap (1), and the center (7A2) is the optical axis (5C) and central axis of the light source (2C). It is placed so that it intersects with (X) and the mirror surface (7A1) intersects the optical axis (5C) at an angle of about 45 °. The center (7B2) of the mirror (7B) is the light axis (5C) of the light source (2C) and the half mirror (7A) is the light source (2C).
And the mirror surface (7B1) is half mirror (7B1).
Light from the light source (2C) that has passed through (A) is totally reflected there, and reaches the upper surface of the cap (1), for example, the light from the light source (2A) in the example of FIG. 4 to the cap (1). As described above, they are arranged orthogonal to the optical axis (5C) and inclined downward. Or, the other mirror (7C), the center (7C2), the optical axis (5C of the light source (2C)
C) and the center (7A2) of the half mirror (7A) intersect with the extension line of the line segment (7C3) that is substantially orthogonal to each other, and the mirror surface (7C1) is the light source (2C which is reflected by the half mirror (7A). ) From the mirror surface (7C
It is reflected again at 1) and is reflected on the upper surface of the cap (1), for example
As in the case of the light from the light source (2B) in the example in the figure, the light source (2B) is arranged so as to reach the cap (1) at right angles to the line segment (7C3) and inclined downward.

Therefore, in the example shown in FIG. 5, although there is only one light source, under the action of the half mirror (7A), the mirrors (7B) and (7
C) acts as if it were the two light sources (2A) and (2B) in the example of FIG. Therefore, the function and effect are almost the same as those in the example of FIG.

In the example of FIG. 5, as shown in FIG.
(3) is arranged below the half mirror (7A).

6A and 6B are respectively a top view and a perspective view of a main part of still another embodiment of the present invention. The example of FIG. 6 has the same components as the example of FIG. Therefore, in FIG. 6, the same symbols as in FIG. 5 indicate the same elements as each other. The main difference between the example of FIG. 6 and the example of FIG. 5 is the mirror (7B) and
The inclination of (7C) is different, and the optical axis (5C) of the light source (2C)
Is off from the optical axis of the photoelectric conversion sensor (3) or the central axis (X) of the cap (1).

That is, as shown in FIG. 6A, the mirror surface (7B1) of the mirror (7B)
Is tilted approximately 45 ° with respect to the optical axis (5C) of the light source (2C), and the mirror surface (7C1) of the mirror (7C) is approximately 45 ° with respect to the line segment (7C3).
Tilt. Therefore, the mirror surfaces (7B1) and (7C1) of both mirrors (7B) and (7C) are parallel to each other except that they are inclined downward. Also, the two mirror surfaces (7B1) and (7C1) have optical axes (5C) and (7C1) so that the light reflected there may irradiate the cap (1) disposed therebelow, as shown in FIG. 6B. Line segment (7C
Of course, it is inclined downward with respect to 3). Also in this case, the light emitted from the light source (2C), divided into two directions by the half mirror (7A), and reflected by both mirror surfaces (7B1) and (7C1), respectively, is the center (O) of the cap (1). Irradiating the surface of the cap (1) so that they are substantially orthogonal to each other is the same as in the example of FIGS. 4 and 5. Also, photoelectric conversion sensor (3)
Are arranged so that the central axis (X) of the cap (1) and its optical axis coincide with each other. Therefore, the operational effects of the sixth example and the examples of FIGS. 4 and 5 are substantially the same.

In the fifth and sixth examples, the half mirrors (7A), mirrors (7B), (7C), etc. are supported by suitable adjusting and supporting means (not shown), and their respective angles are Can be prepared.

Also, instead of installing the optical mask on the front surface of the light source (2C), it should be placed on the front surface of the mirror surface of the half mirror (7A), or on the front surface of the mirror surface of each mirror (7B), (7C). May be.

Incidentally, in the example of FIG. 5 and FIG. 6 also, the photoelectric conversion sensor
Of course, the output of (3) is processed by the electronic processing device (4) to inspect for defects on the surface of the object to be inspected.

〔The invention's effect〕

As described above, according to the present invention, the light source using the special optical mask irradiates the surface of the inspected object having unevenness so that the diffused reflection is uniform on the surface of the inspected object. The entire surface of the object can be inspected easily and surely by one inspection.

According to the examples of FIGS. 5 and 6, in addition to the effects of the examples of FIGS. 1 and 4, only one expensive light source and optical mask combination is required.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a main part of an example of the present invention, FIGS. 2 and 3 are front views of an example of the optical mask shown in FIG. 1, and FIGS. FIG. 7A and FIG. 7B are schematic diagrams of the main part of another example, FIG.
FIG. 9 is a schematic diagram of a conventional surface inspection apparatus, and FIG. 9 is a schematic diagram for explaining the operation thereof. In the figure, (1) is the object to be inspected, (2A), (2B), (2C) are the light sources,
(3) is a photoelectric conversion sensor, (4) is an electronic processing device, (6A), (6
B) and (6C) are optical masks, (7A) is a light splitting means, (7B) and (7C)
Denote light reflecting means, respectively.

Claims (2)

[Claims] 1. Light splitting means for splitting light from one light source into two directions, and light reflecting means for irradiating the light in two directions from the light splitting means onto the surface of the object to be inspected obliquely from above. In the device for inspecting the surface of the object to be inspected by imaging the surface of the object to be inspected, which has an uneven surface irradiated by the light source, and processing the video signal with an electronic processing device, An opaque portion that does not illuminate the surface of the object to be inspected in a lower substantially triangular area centered on the center of the surface of the object to be inspected In the other ranges, an optical mask is provided as a transparent portion that transmits light and irradiates the surface of the object to be inspected, and the light in the two directions is arranged so as to be orthogonal to each other. Irradiate the surface of the Surface inspection apparatus characterized by irregular reflection of was made to be substantially uniform. 2. The surface inspection apparatus according to claim 1, wherein the one light source emits substantially parallel light.