JPH0131958Y2 - - 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 inspect holes that occur in such transparent capsules.

Figure 1 is a configuration diagram showing a conventional example of such an inspection device, Figure 1A is an explanatory diagram illustrating the photo sensor output when a capsule is scanned helically, and Figure 1B is an illustration of the illumination in the spherical part of the capsule. FIG. 3 is an explanatory diagram for explaining the relationship between light and reflected light. In FIG. 1, 11 is a photo sensor, 12 is a half mirror, 13 is an illumination light source, and 14
is an objective lens, and its optical axis is shared by the illumination system composed of the half mirror 12, illumination light source 13, and objective lens 14, and the light receiving system composed of the photo sensor 11, half mirror 12, and objective lens 14. Therefore, it will be referred to as a ``coaxial reflective optical inspection device'' hereafter. 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 the half mirror 1
The irradiated light from the light source 13 passes through the capsule 2 and the lens 14 and is scanned in a spiral pattern (hereinafter also referred to as a helical scan). 1
4 and the photo sensor 1 via the half mirror 12.
1, an output of a predetermined level can be obtained 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), reflected light cannot be obtained regardless of whether there is a hole or not. In other words, the 1st A
As shown in Figure A, the hole 2a in the cylindrical part is detected as shown in A in Figure 1A-B, but the hole 2b in the spherical part is not detected as shown in B in Figure 1A-B. be. Another method of guiding the reflected light from the spherical part to the photo sensor is to make the objective distance smaller than the lens diameter, that is, to make the aperture angle larger, in the coaxial reflection type inspection device 1 as shown in Fig. 1. Conceivable. This eliminates areas without reflected light, but instead increases the aperture angle, which reduces the depth of field of the photo sensor system, and even if the subject moves slightly, the photo sensor output fluctuates greatly, making detection difficult. It has the disadvantage of becoming.

[Purpose of invention]

This idea was made under these circumstances, and it not only deepens the depth of field of the photo sensor system, but also allows highly accurate detection with almost no effect even if the object distance moves a little. The purpose of the present invention is to provide a coaxial reflective optical inspection device.

[Key points of the idea]

On the optical axis shared by the illumination system and light receiving system of a coaxial reflective optical inspection instrument, an optical system consisting of a half mirror near the optical axis and a total reflection mirror around the optical axis is placed along the optical axis. By arranging the lens at an angle of about 45 degrees, the aperture angle of the illumination light passing through the objective lens and the aperture angle of the light receiving system (reflected light) are made different from each other, thereby deepening the depth of field. That's what I did.

[Example of idea]

Hereinafter, embodiments of this invention will be described with reference to the drawings.

Figure 2 is a configuration diagram showing an embodiment of this invention.
Figure A is an explanatory diagram for explaining the photo sensor output in that case. As is clear from FIG. 2, this embodiment has a mirror (optical system) 1 consisting of a half mirror section 12a and a total reflection mirror section 12b.
2' and that the aperture angle on the objective side is increased, the other features are the same as in FIG. 1.

Here, its effect will be explained.

The light emitted from the illumination light source 13 is transmitted to the mirror 1
After being reflected at 2', the capsule 2 is illuminated through the lens 14. In this case, the angle of illumination can be widened by increasing the aperture angle θ _I . Of the light reflected on the surface of the capsule 2, the light reflected within the aperture angle θ _I reaches the mirror 12' via the lens 14 again. Furthermore, the light that has reached the half mirror 12a is divided into two parts, with one part heading towards the photo sensor 11 and the remaining part heading towards the illumination light source 13. All of the light that has reached the perfect reflection mirror 12b is directed toward the illumination light source 13, and is prevented from entering the photo sensor 11. That is, when looking at the lens 14 from the photo sensor 11, the optical path is narrowed by the perfect reflection mirror 12b, so the equivalent aperture angle is θ _S , which is smaller than the aperture angle θ _I of the illumination system. As a result, the depth of field as seen from the photo sensor 11 becomes deeper, and even if the capsule surface moves somewhat in the optical axis direction, changes in the amount of light reaching the photo sensor 11 can be reduced. In addition,
When the aperture angle θ _I of the illumination system is increased, the depth of field of the illumination system becomes shallower, and there remains the possibility that the illuminance will change significantly even with a slight movement of the capsule in the optical axis direction. Considering that it is not necessarily necessary to use the illumination system at the optimum focus unless the amount of light is insufficient, it can be said that this invention does not cause any particular problems. In addition, the photo sensor 1 when performing a helical scan of the capsule 2 using such an inspection device 1
The output waveform of 1 is shown in Figure 2A (b).
According to this, the hole 2b formed in the spherical portion of the capsule 2 as shown in FIG. 2A (a) can be reliably detected as shown by C in FIG.

FIG. 3 is a sectional view showing the structure of a mirror used in this invention. In the figure, 21 is glass, 22 and 23 are vapor deposited films, 22 forms a half mirror, and 23 forms a total reflection mirror. That is, in Figure A, a vapor deposited film 22 that becomes a half mirror is formed on a glass 21, and a vapor deposited film 2 that becomes a total reflection mirror is further formed on top of it.
In FIG. 3B, the half mirrors 21, 22 and the reflecting plate 24 are made independently and used by overlapping them. In both cases A and B, a cutout or hole 25 is formed in the vicinity of the optical axis. This cutout or hole 25
It is desirable to change the shape depending on the subject to be photographed, and for example, it can be as shown in FIG. Note that FIG. 4 is a top view showing the structure of the mirror. In other words, the shape of the half mirror portion projected in the optical axis direction matches the field of view or the shape of the subject.Here, this is called an "ellipse".
The case is shown.

[Effect of idea]

As described above, according to this invention, instead of a coaxial reflective half mirror, the central part is a half mirror,
Since a mirror is provided whose peripheral portion serves as a total reflection mirror, the following effects can be expected.

B) Since the aperture angles of the illumination system and the photo sensor system can be made different, and in particular the aperture angle of the photo sensor system can be made small, the illumination angle can be increased without reducing the depth of field.

(b) With half-mirror lighting, only about half of the irradiated light reaches the subject, but this idea uses a total reflection mirror, so most of the irradiated light reaches the subject, resulting in high lighting efficiency. Become.

c. As a result, even holes in the spherical part of the capsule can be reliably detected.

Note that this invention can be widely applied not only to the above-mentioned pharmaceutical capsules but also to general inspection devices that inspect holes formed on the surface of objects having a spherical shape or an equivalent shape.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a conventional example of a coaxial reflective optical inspection device, and FIG. 1A is an explanatory diagram illustrating the photo sensor output when a capsule is helically scanned.
Figure 1B is an explanatory diagram for explaining the relationship between irradiated light and reflected light in the spherical part of the capsule, Figure 2 is a configuration diagram showing an embodiment of this invention, and Figure 2A is an explanation of the photo sensor output in that case. Explanatory diagram, 3rd
The figure is a cross-sectional view showing the structure of the mirror (optical system).
The figure is a top view showing the structure of a mirror (optical system). Code explanation, 1...Coaxial reflective optical inspection device, 11
...Photo sensor, 12...Half mirror, 1
2'...Mirror (optical system), 13...Illumination light source, 1
4...Objective lens, 2...Capsule (subject),
3...Incoming light, 4...Normal line, 5...Reflected light, 21
... Glass, 22, 23 ... Deposited film, 24 ... Reflection plate, 25 ... Cutout or hole.

Claims (1)

[Claims for Utility Model Registration] 1. A system comprising an illumination system for illuminating an object to be inspected and a light receiving system for receiving reflected light from the object to be inspected, the illumination system and the light receiving system sharing an optical axis. In this coaxial reflection type optical inspection device, an optical system is installed at a predetermined position on the optical axis, the predetermined portion near the optical axis is a half mirror portion, and the peripheral portion is a total reflection mirror portion. A coaxial reflective optical inspection device characterized by being arranged at an angle. 2 Utility Model Registration Scope of Claims 1. The coaxial reflection type optical inspection device according to claim 1, wherein the total reflection mirror portion is formed by vapor deposition of a predetermined material on a predetermined portion of a half mirror. Shape optical inspection device. 3 Utility Model Registration Scope of Claims 1. In the coaxial reflective optical inspection device as set forth in claim 1, the optical system comprises one half mirror plate and one full plate in which a predetermined portion near the optical axis is cut out in a predetermined shape. A coaxial reflective optical inspection device characterized by being formed by overlapping a reflecting plate.