JPH0114915Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] This invention relates to an optical inspection device suitable for use in inspecting surface flaws on a cylindrical object having a spherical end such as a pharmaceutical capsule.

[Prior art and its problems]

Surface inspection of cylindrical objects with spherical ends, such as pharmaceutical capsules, has conventionally been carried out exclusively by visual inspection, but recently automatic visual inspection devices using machines have also been proposed. By the way, pharmaceutical capsules are generally classified into opaque capsules and transparent capsules depending on the presence or absence of titanium oxide. When inspecting defects such as holes that occur in capsules, it is difficult to detect them, especially in transparent capsules, but the applicant has proposed an inspection device that can detect holes that occur in such transparent capsules. .

Fig. 1 is a configuration diagram showing a conventional example of such an inspection device, Fig. 1A is a waveform diagram showing the photo sensor output when a capsule is scanned helically, and Fig. 1B is an illumination light at the spherical part of the capsule. FIG. 3 is an explanatory diagram for explaining the relationship between and reflected light. In FIG. 1, 11 is a photo sensor;
2 is a half mirror, 13 is an illumination light source, and 14 is an objective lens; the half mirror 12, the illumination light source 13
and an illumination system composed of an objective lens 14;
Since its optical axis is shared by a light receiving system composed of a photo sensor 11, a half mirror 12, and an objective lens 14, it will be referred to as a "coaxial reflective optical inspection device" hereinafter. Reference numeral 2 denotes a pharmaceutical capsule, which is transported in the axial direction while rotating around a longitudinal axis as indicated by arrow R in the figure. Therefore, the surface of the capsule 2 is scanned in a spiral manner (hereinafter also referred to as a helical scan) by the irradiated light from the light source 13 via the half mirror 12 and the lens 14. Since the light is totally reflected on the surface of the capsule 2 and is applied to the photo sensor 11 via the lens 14 and the half mirror 12, an output of a predetermined level is sequentially extracted from the photo sensor 11 according to the helical scan. Here, if a hole or the like indicating a defect exists in the cylindrical portion of the capsule 2, the irradiated light will not be reflected by the hole, so that the hole occurring in the transparent capsule 2 can be detected.
By the way, this is a case where the cylindrical part of the capsule 2 is scanned, but in the spherical part, as shown in FIG. Since the light is reflected to the opposite side (see reference numeral 5), no reflected light can be obtained regardless of whether there is a hole or not. In other words, the hole 2a in the cylindrical part, as shown in Figure 1A A, is detected as shown in A in Figure 1B, but the hole 2b in the spherical part, as shown in B in Figure 1B, cannot be detected. There are drawbacks.

[Purpose of invention]

This invention was made under these circumstances, and the object is to provide an optical inspection device that can detect holes in the spherical part of a transparent capsule in the same way as holes in the cylindrical part.

[Key points of the idea]

The key point is that two sets of auxiliary illumination sources are installed at an appropriate angle in the longitudinal direction of the object to be inspected, with the optical axis of the coaxial reflective optical inspection device as the center. The main illumination works effectively for the holes formed in the spherical part, and the auxiliary lighting works effectively for the holes formed in the spherical part.

[Example of idea]

Figure 2 is a configuration diagram showing an embodiment of this invention.
Figure A is a waveform diagram showing the sensor output waveform, Figure 2B is an enlarged view showing the vicinity of the spherical part of the capsule, Figure 2C is an explanatory diagram explaining the difference in the sensor output waveform, and Figure 2D has scratches. FIG. 3 is a waveform diagram comparing and showing cases where the signal is present and cases where the signal is not present.

As is clear from FIG. 2, this embodiment
Conventional coaxial reflective optical inspection device 1 shown in Fig. 1
A pair of auxiliary light sources 15 ₁ and 15 ₂ are placed near each end of the objective lens 14 that has a predetermined angle with the optical axis of the inspection device and is cut by a vertical plane that includes the longitudinal axis of the capsule 2. It is characterized by the fact that it is provided for each. At this time, if the optical axes of the auxiliary light sources 15 ₁ and 15 ₂ are simply installed at a predetermined angle with respect to the optical axis of the inspection device 1, there will be an area where there is no illumination light, as shown by the symbol C in the figure. Therefore, in order to reduce this as much as possible, the auxiliary illumination sources 15 ₁ ,
15 ₂ is provided close to the objective lens 14. The angle between the optical axes of the auxiliary light sources 15 ₁ and 15 ₂ and the optical axis of the inspection device 1 is selected to be about 45 degrees, but can be selected within the range of 30 to 60 degrees. Also,
The intersection points of the optical axis of the inspection device 1 and the optical axes of the auxiliary light sources 15 ₁ and 15 ₂ are made to substantially coincide on the surface of the capsule 2, and the focus of the inspection device 1 is made to coincide with the intersection points. By doing so, it becomes possible to illuminate and inspect the spherical part of the capsule, which cannot be illuminated by the light source 13 alone.This point will be explained in more detail with reference to Figures 2A to 2D. do.

Now, as shown in FIG. 2B, the illumination angle of the illumination light source 13 is assumed to be 2θ _M , and the illumination angle of one of the auxiliary light sources 15 ₁ is assumed to be 2θ _S. Note that θ _C is an area without illumination light. Here, suppose that an arbitrary point P on the spherical part of the capsule 2 is observed by the inspection device 1, and at that time, if the angle between the tangential plane at the point P and the optical axis of the inspection device 1 is θ _R , This angle θ _R is the observation point P
is a measure of how far away from the cylindrical part of the capsule it is, but this differs between when only the light source 13 is used and when the auxiliary light source 15 ₁ is used together; in the former case, θ _R < θ _M ; The latter can be expressed as θ _R <(2θ _M +θ _C +θ _S ), and it can be seen that the observation field (θ _R ) is expanded when the auxiliary light source 15 ₁ is also used.

This means that when comparing the photo sensor outputs when only the illumination light source 13 is used and when only the auxiliary light source ₁₅₁ is used, the results are as shown in Figure 2C A and B, whereas when these light sources are used together, This can also be understood from the fact that it becomes like this.
However, even if these light sources are used together, D
However, if the above angle θ _C is θ _C 0, it is possible to almost eliminate this concave portion. In other words, the shape of this singular part D is determined by the value of the angle θ _C , and θ _C <0
When , it is concave, when θ _C 0, it is almost flat, and,
If θ _C <0, it can be said that the shape is convex. Note that θ _C <0 is theoretical and does not actually exist.

From the above, when the spherical part of a transparent capsule is scanned using the inspection device of this invention, a peculiar part shown by C in Figure 2C or D in Figure 2D A will occur, but this spherical part If there is a hole 2b as shown in Fig. 2D, the waveform will be D',
It becomes like E. In other words, D' is the above-mentioned singularity caused by the illumination system, and E is the waveform caused by defects such as holes in this singularity.
They can be distinguished from each other because the speeds of change when scanning the D' section and the E section are significantly different from each other. However, singular part D or
If the change in D′ changes by more than 1/2 compared to the level of the cylindrical part, the speed difference mentioned above cannot be detected, and detection may become impossible. Therefore, adjust the illumination system appropriately. is necessary. Although the above explanation has been given for the auxiliary light source on the left side of Fig. 2, the action and effect are the same for the auxiliary light source on the right side.As a result, the photo sensor output when the entire capsule is helically scanned is
It can be represented as shown in the figure, which makes it possible to sufficiently inspect the spherical portion for defects.

[Effect of idea]

As described above, according to this invention, at least one pair of auxiliary light sources are provided on both sides of the detector that coincide with the direction of movement of the capsule and are at a predetermined angle with the optical axis of the detector. Since it is possible to detect defects in the spherical part of the capsule that cannot be illuminated and therefore cannot be detected with other inspection instruments, it has the advantage of improving detection accuracy and expanding the inspection area. be.

[Brief explanation of drawings]

Figure 1 is a configuration diagram showing a conventional example of an optical inspection device, Figure 1A is a waveform diagram showing the photo sensor output when a capsule is helically scanned, and Figure 1B is the relationship between irradiated light and reflected light at the spherical part of the capsule. FIG. 2 is a configuration diagram showing an embodiment of this invention, FIG. 2A is a waveform diagram showing the sensor output waveform, and FIG. 2B is an enlarged view showing the vicinity of the spherical part of the capsule. , FIG. 2C is an explanatory diagram illustrating differences in sensor output waveforms, and FIG. 2D is a waveform diagram comparing cases with and without scratches. Code explanation, 1...Coaxial reflective optical inspection device, 11
...Photo sensor, 12...Half mirror, 13
...Illumination light source, 14...Objective lens, 15 ₁ , 1
5 ₂ ... Auxiliary light source for illumination, 2... Capsule (object to be inspected), 2b... Hole (flaw), 3... Incident light, 4...
Normal, 5...Reflected light.

Claims (1)

[Claims for Utility Model Registration] 1. A cylindrical article having spherical portions at both ends, which is rotated around a longitudinal axis and conveyed in the longitudinal direction, is transported in a predetermined direction from a direction perpendicular to a horizontal plane including the longitudinal axis. The illumination system includes an illumination system that illuminates through an objective lens, and a light receiving system that receives reflected light from the article through the objective lens, and the illumination system and the light receiving system share a part of the optical axis with each other. In the coaxial reflective optical inspection device, at least one auxiliary illumination system is provided near each end of the objective lens cut by a vertical plane including the longitudinal axis of the article at a predetermined angle with the optical axis. . A coaxial reflective optical inspection device, characterized in that the auxiliary illumination system illuminates a spherical portion of the article and the reflected light is guided to the light receiving system. 2 Utility Model Registration Scope of Claims 1. In the coaxial reflective optical inspection device according to claim 1, the points of intersection of the optical axes of the illumination system and the auxiliary illumination system coincide at substantially the surface of the article, and the focusing point of the inspection device A coaxial reflective optical inspection device characterized in that the coaxial reflection type optical inspection device is configured such that the intersection point coincides with the intersection point.