JPH0610657B2 - Surface inspection device - Google Patents

Description

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

[Conventional technology]

Bottle caps and beer can ends are usually made of plastic or metal and are flat (top or bottom)
Is circular. Further, in order to sufficiently withstand the pressure fluctuation due to the liquid in the container, in other words, to increase its strength, such caps and ends are formed with a plurality of concentric (ring-shaped) or spiral-shaped irregularities. It is usually done.

FIG. 5A is a top view of a cap (1) of a metal bottle, which is an example of the object to be inspected, and FIG. 5B shows B- of FIG.
It is sectional drawing along the B line. In the figure, (a),
(B) and (c) are concentric concavo-convex as described above,
(A) is a ring-shaped protrusion protruding upward from the upper surface of the cap (1), and (b) and (c) are ring-shaped protrusions (a) of the upper surface of the cap (1). The boundaries of the ring-shaped steps provided in the inner part are shown respectively.

FIG. 6 is a schematic diagram of an example of a conventional surface inspection device for inspecting the presence or absence of defects such as flaws on the surface of the cap (1) of the bottle as the inspection object as shown in FIGS. 6 and 5. 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 irregularities, 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. 7 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. 7, of the light from the light source (2), the surface of the cap (1) with respect to the light at the central portion, that is, the light traveling substantially along its optical axis (A). Of the ring-shaped protrusions (a) and boundaries (b) and (c) of the cap, the cap (1)
With respect to the center (O) of the light source (2), the portions (a ′), (b ′), (c ′) indicated by the thick line and the center (O ′) of the ring-shaped protrusion (a) (a ′) ), The part (a ″) on the opposite side is as shown in FIG. 5B and FIG.
The part that rises like a wall. These parts (a '),
In (b '), (c') and (a "), the diffuse reflection of light is remarkably larger than the diffuse reflection in other parts, and the diffuse reflection light of these parts is directly incident on the video camera (3). On the other hand, the protrusions (a) and the boundaries (b) and (c), which are the same as each other, stand up in a wall shape other than the portions (a '), (b'), (c ') and (a "). Most of the light diffused and reflected by the portion travels in the direction indicated by the arrow (d) in FIG. 7 and does not enter the video camera (3) directly. Of course, the cap
Light that is diffusely reflected as usual on the flat surface of (1) enters the video camera (3), is output as a video signal of the cap (1), and is input to the electronic processing device (4). ) Is processed as described above, and the cap (1) is not defective,
That is, the quality of the cap (1) is determined. The angular range of the arcuate portions (a ′), (a ″), (b ′) and (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 diffuse reflection of light at the surface portions (a '), (b'), (c '), and (a ") of the cap (1) is remarkably higher than that of other portions. Since these diffused reflections are directly incident on the video camera (3),
In (3), the parts (a '), (b'), (c ') and (a ") are significantly brighter than the other parts,
These parts (a '), (b'), (c ') and (a ")
Not only is it impossible to inspect for defects, but it also adversely affects the inspection of other parts. In order to solve this, inspect the other part of the surface of the cap (1) excluding the part that causes significant diffuse reflection, or irradiate the surface of the cap (1) with light from the light source (2). The surface of the same cap (1) must be divided into parts and the inspection must be repeated many times while changing the angle to be changed, which is time-consuming and causes a large loss in time.

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, in an apparatus for inspecting the surface of an inspected object by imaging the surface of the inspected object having an uneven surface illuminated by a light source with a photoelectric conversion sensor and processing the video signal by an electronic processing device. In front of the light source, the light from 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 the range of 2), an optical mask that is a transparent portion that transmits light and irradiates the surface of the inspection object is arranged, and the light source is arranged so that their optical axes are orthogonal to each other.
Individually arranged, the light source illuminates the surface of the object to be inspected obliquely from above, so that the diffused reflection of light there is substantially uniform.

[Action]

In the present invention, the uneven surface of the object to be inspected (1) is formed by combining the two surfaces of the light sources (2A) and (2B) having special optical masks (6A) and (6B), respectively. The irregular reflection of light on the surface is irradiated so that it becomes almost uniform, and this irregular reflection light is received by the video camera (3), and the video signal from it is processed by an electronic processing device.
By processing in (4), the surface of the object to be inspected (1) is inspected for defects.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. In the present invention, the photoelectric conversion sensor (video camera) (3) and the electronic processing device (4) are exactly the same as those of the conventional example shown in FIG. The arrangement with respect to the cap (1), which is an example of the object to be inspected, is substantially the same as that of the example shown in FIG. 6, and therefore, these 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 for irradiating 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 so that they intersect at the center (O) of the cap (1). 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 there is no optical mask (6A), the light from the light source (2A) will be emitted from the cap as described in FIGS. 6 and 7.
The circular protrusions (a) on the surface of (1) have arc-shaped portions (a ′), (a ″) whose angular range is smaller than 90 °, boundaries (b),
The portions (b ') and (c') of (c) are remarkably irregularly reflected as compared with the other portions, and are directly incident on the video camera (3), causing the inspection failure as described above. Therefore, in the present invention,
An optical mask (6A) is provided in front of the light projection surface of the light source (2A),
The light from the light source (2A) is at least part (a '),
(A ″), (b ′) and (c ′) do not enter. Of course, the light from the light source (2A) is the portion (a ′),
It is incident on the surface of the cap (1) other than (a ″), (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 such as glass, and four triangular portions (6A1), (6A2), (6A3), (2A) with two diagonal lines. 6A4) and two opposing triangular portions, in this example, the portions (6A2) and (6A4) are made opaque (shown in black in FIG. 2) using, for example, black paint, (6A1) and (6A3) are transparent parts.

As shown in FIG. 1, the optical mask (6A) as described above is arranged in front of the light projection surface of the optical (2A) with the opaque portions (6A2), (6A4) arranged vertically and the light of the light source (2A). 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 portion (a ') of the cap (1),
(A ″), (b ′), (c ′) are never reached,
It reaches the surface of the cap (1) other than those parts, is diffused 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. Processed by (4), the surface of the cap (1) is inspected. 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 ') of the cap (1),
Since (a ″), (b ′) and (c ′) are not reached,
These parts 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. Interval, that is, at least 1/2 of each range (ARC) of arcuate parts (a '), (a ") ...
As described above, it is arranged so that the surface of the cap (1) similar to the former is irradiated at a position separated by (180 ° -1 / 2 ARC) or less. Therefore, by combining the light source (2B) and the optical mask (6B), the light source
(A ') on the surface of the cap (1) where light did not reach due to the combination of (2A) and the optical mask (6A),
(A ″), (b ′), (c ′), etc. are irradiated.
Due to the presence of the optical mask (6B), the light source (2) is provided on the surface of the cap (1) corresponding to the portions (a '), (a "), (b') and (c ') with respect to the light source (2A). 2B) does not reach, but (these parts are the light source (2A) and the optical mask (6
It has already been irradiated by the combination of A)), and reaches the other portion 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 portions (a '), (a "), (b'), (c ') that make the surface of the cap (1) impossible to be inspected due to the diffused reflection of the incident light remarkably, Although an optical mask is used so as not to irradiate light from this light source, since it is adapted to irradiate using another light source having an optical mask, the cap (1) having a ring-shaped or arc-shaped uneven portion is formed. The surface can be inspected easily and surely 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, for example, the portion of the surface of the object to be inspected that causes unnecessary diffused reflection is not irradiated with light, for example, Three
As shown in the figure, it may have a vertically symmetrical drum-shaped opaque portion (6a1), (6a2) with respect to the center (0A) (other portion (6a
3) 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 both optical axes (5A) and (5B) are
At the center (O) of the cap (1), they are arranged so as to be substantially orthogonal to each other. The optical masks (6A) and (6B) shown in FIG. 2 are 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
The fan-shaped parts (1A) and (1A ') in the angular range of ° are irradiated,
Of the surface of the cap (1), the fan-shaped portions (1B), (1B ') in the remaining approximately 90 ° angular range that are symmetrical with respect to the center (O) and the optical axis (5B) of the other light source (2B). Is not irradiated. In this case, the arc-shaped portions (a '), (b'), which rise up like a wall on the surface of the cap (1) which causes the above-mentioned remarkable diffuse reflection,
Since (c ') and (a ") are present in the fan-shaped portions (1B) and (1B') which are not illuminated by the light source (2A), respectively, they do not cause the inspection failure of the surface of the cap (1).
Similarly, by the combination of the light source (2B) and the optical mask (6B),
The fan portions (1B) and (1B ') which were not illuminated by the combination of the light source (2A) and the optical mask (6A) are illuminated, but the remaining fan portions (1A) and (1A') are not illuminated. Of course, the light source (2B)
And the portions (a ′), (b ′), (c ′) and (a ″) that cause significant diffuse reflection for the combination of the optical mask (6B) are
Since the portions (1A ') and (1A) not illuminated by this combination are present respectively, the surface of the cap (1) cannot be inspected.

As described above, according to the example of FIG. 4, the entire surface of the cap (1) has the combination of the light source (2A) and the optical mask (6A) and the combination of the light source (2B) and the optical mask (6B). The different diffuse reflections of the incident light on the surface of the cap (1) are substantially uniform, and thus the normal diffuse reflection of the incident light on the surface of the cap (1) is substantially uniform. Surface inspection can be done more accurately.

〔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.

[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 FIG. 4 is a main view of another example of the present invention. 5A and 5B are top and sectional views of the object to be inspected, FIG. 6 is a schematic diagram of a conventional surface inspection apparatus, and FIG. 7 is a schematic diagram for explaining the operation thereof. . In the figure, (1) is an object to be inspected, (2A) and (2B) are light sources, (3) is a photoelectric conversion sensor, (4) is an electronic processing device, and (6A) and (6B) are optical masks. Show each.

Claims (2)

[Claims] 1. An apparatus for inspecting the surface of an object to be inspected by capturing an image of the surface of the object to be inspected, which has an uneven surface illuminated by a light source with a photoelectric conversion sensor, and processing the video signal thereof by an electronic processing device. Light from the light source in front of the light source is an opaque portion which does not illuminate the surface of the object to be inspected in a lower substantially triangular area centered on the surface center of the object to be inspected and in an upper substantially triangular area symmetrical to this. In the other range, an optical mask is provided as a transparent portion that transmits light and irradiates the surface of the object to be inspected, and two light sources are arranged so that their optical axes are orthogonal to each other. A surface inspection device characterized by irradiating the surface of an object to be inspected obliquely from above so that the diffused reflection of light there is substantially uniform. 2. The surface inspection apparatus according to claim 1, wherein each of the two light sources emits substantially parallel light.