JPH08271433A - Tablet inspection equipment - Google Patents

Abstract

PURPOSE: To shorten the processing time by providing an optical system for passing the polarized component in the reflected light from an object and a package through another polarization filter and focusing an image thereby lessening the imaging load. CONSTITUTION: The light is split and a press fit package sheet 104 is irradiated from four directions through an optical fiber bundle 105 with polarized light from a polarizer 106. Only a polarized light of specified azimuth angle in the reflected light from the sheet 104 passes through an analyzer 107 and focused through a lens group 108. The image is observed directly or monitored. The sheet 104 is transferred on a belt conveyor 206 to a predetermined position and a position sensor 203 is actuated. Consequently, a controller 202 delivers the image to an image processor 201 which returns a processed image back to the controller 202. The controller 202 decides pass/fail of the processed image and delivers a passed product to next process whereas removes a failed product to the outside of the line through a failed product removing unit 205. With such arrangement, defect or foreign matter present in a tablet in the sheet 104 can be detected easily and accurately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for optically inspecting an object to be inspected in a packaged package, that is, a small solid substance such as a tablet, a capsule or a candy (hereinafter simply referred to as a tablet).

[0002]

2. Description of the Related Art A tablet is packaged in a metal foil and a transparent synthetic resin film, and is generally made of PTP (Press Thro
It is called a "ugh Package" sheet. This is a method in which a pocket is formed on a vinyl chloride film (hereinafter, abbreviated as a vinyl chloride film) by heat molding, a tablet is put in this pocket, and then aluminum foil is adhered and sealed.
The inspection object is a tablet, and the object to be detected is a defect such as a crack or a chip of the tablet. Furthermore, the presence of foreign matter such as hair and dust is also an object to be detected.

Inspection of tablets is generally performed visually. Visual inspection includes a method of directly observing the inspection object, a method of observing an image of the inspection object through an eyepiece lens, and a method of monitoring on the screen. Further, in recent years, an image processing unit is provided to process an image of an object to be inspected, thereby automating and improving the efficiency of the inspection. The conventional tablet inspection will be described with reference to FIG. FIG. 6 is an observation example of a PTP sheet when general illumination such as an indoor fluorescent lamp is used. Since the illumination light is incident on the surface of the PTP sheet from a direction substantially at right angles, the reflected light from the aluminum foil on the back surface of the PTP sheet is strong and the aluminum foil portion 602 appears bright. Therefore, the contrast with the tablet 601 is lowered, and the tablet 601
It is difficult to observe clearly. Also, the reflected light that has passed through the curved surface of the pocket of the PVC film, is reflected by the tablet and the aluminum foil, and is transmitted through the curved surface again and the reflected light from the surface of the curved surface (these reflected light are collectively referred to as the reflected light from the curved surface). ) 603
Obscure the outline of the tablet 601.

To solve this problem, a method has been proposed in which polarized light is used as the illumination light and only the light of the polarized component in one direction out of the reflected light from the tablet or the package is made to enter. However, even with this method, in the inspection of the packaged tablet, the reflected light 603 from the curved surface portion of the pocket was not sufficiently removed, and the outline of the tablet inside could not be made clear.

[0005]

In the inspection of a package in which a tablet is packaged with a metal foil and a transparent synthetic resin film, the light reflected from the metal foil is too strong under the general illumination described above. There is a problem in that the contrast between the peripheral portion and the peripheral portion is too low, or the contour of the tablet inside becomes unclear due to the reflected light from the curved surface portion of the pocket of the PVC film.

Further, in the method of using polarized light as the illumination light and injecting only the light of the polarized component in one direction out of the reflected light from the tablet or the package, it is partially strong in one round of the curved surface of the pocket. There is a problem that the reflected light (regularly reflected light) is incident on the imaging optical system and the entire contour of the tablet inside cannot be clearly observed. For this reason, in the case of visual inspection, the burden on the inspection operator increases and fatigue is accelerated, as well as the accuracy of the inspection,
The stability of the inspection standard was hindered.

In the case of automatic inspection using image processing, by preprocessing such as density gradation conversion and spatial filtering,
Addressed the above issue. However, there are problems that this pre-processing takes time, the cost is increased for high-speed processing, and the parameters need to be changed according to changes in the shape and color tone of the inspection object. The present invention has been made to solve such a problem, and an object of the present invention is to provide a tablet inspection device that can detect the presence of a defect or a foreign matter of an inspection target in a package with high accuracy and easily. To do. This also contributes to reducing the image processing load and shortening the processing time.

[0008]

A tablet inspection apparatus according to the present invention is a tablet inspection apparatus for inspecting an inspection object inside a package sandwiched between a metal foil and a transparent synthetic resin film having a constant stretching direction. , The linearly polarized light by the first polarizing filter, including two diagonal directions opposite to each other in a plane including a straight line parallel to the stretching direction and perpendicular to the synthetic resin film, and a straight line perpendicular to the stretching direction. Opposing diagonals in a plane perpendicular to the synthetic resin film 2
Illumination optical system for irradiating the inspection object through the synthetic resin film from at least one of two oblique directions, and light of a predetermined polarization component of the reflected light from the inspection object and the package. And an imaging optical system for forming an image through a second polarizing filter,
It is equipped with.

The first and second polarization filters may be provided rotatably around the optical axis. Further, it is also possible to dispose the image pickup device on the image forming plane of the image forming optical system.

[0010]

The inventors of the present invention, as means for highly accurately and easily inspecting the inspection object inside the packaged package, the metal foil, the transparent synthetic resin film, the angle of polarization of the reflected light from the inspection object ( Hereafter, the azimuth angle is different). The present invention utilizes this difference to remove harmful or useless reflected light, or to control the direction and angle of illumination in advance to prevent the generation of harmful reflected light.

In the inspection apparatus of the present invention, the tablet is observed by irradiating polarized illumination light from at least one of a direction parallel to and a right angle to the stretching direction of the synthetic resin film and an oblique direction to the surface of the synthetic resin film. Most of the generation of reflected light, which is not convenient for, can be eliminated. Furthermore,
Of the reflected light from the PTP sheet, only the light of the polarized light component in one direction is incident and imaged through the polarizing filter, and the reflected light from the tablet is hardly reduced and the reflected light from the metal foil and synthetic resin film (background (Light) can be removed and a clear image can be obtained.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a side view showing the outline of the basic configuration of the tablet inspection device according to the present invention. FIG. 2 is a perspective view showing a schematic configuration of a tablet inspection apparatus which is completely automated using the configuration of FIG.

In FIG. 1, a tablet 101 is replaced with an aluminum foil 10
The PTP sheet 104 is formed by packaging 2 and the PVC film 103. The illumination optical system has a light source (not shown), an optical fiber bundle 105, and a polarization filter (polarizer) 106. The imaging optical system includes a polarization filter (analyzer) 10
7 has a lens group 108. In addition to these, an image pickup element 109 is provided. Polarizing filter (analyzer) 10
7, the lens group 108, and the image sensor 109 are installed right above the PTP sheet 104. As the image sensor 109,
For example, a CCD camera may be used.

The light emitted from the light source is branched into four, and the optical fiber bundle 105 irradiates the PTP sheet 104 with light polarized by a polarizing filter (polarizer) 106 from four directions. One of the four facing directions is
It is in a plane perpendicular to the PVC film including a line parallel to the stretching direction. In FIG. 1, two of the four illumination optical systems are branched.
Only one (one pair opposite) is shown. With respect to the reflected light from the PTP sheet 104, only the polarized light of a specific azimuth angle passes through the polarizing filter (analyzer) 107 and is imaged by the lens group 108. Observe this image directly or monitor it on the screen.

FIG. 2 is a schematic block diagram of a case where an image processing device 201, a controller 202, a position sensor 203, a rotation detection unit 204 and a defective product extracting device 205 are added to FIG. 1 for complete automation. is there. The tablet inspection device of the present invention is installed immediately after the packaging process of the PTP sheet packaging device. Generally, the PTP sheet 104 is placed on the belt conveyor 206 in an aligned state and conveyed to the position of the tablet inspection apparatus of the present invention. PTP sheet 104
The position sensor 203 is activated to send a signal to the controller 202 when the robot reaches a predetermined position. At this timing, the controller 202 sends a signal to the image processing apparatus 201, and the image processing apparatus 201 sends the processed image to the controller 202.

The controller 202 judges whether the processed image is good or bad, and if it is "good", it is carried to the next step, and if it is "bad", it is carried to the position of the defective product extracting device 205 by a belt conveyor, Remove out of line. This conveyance distance is measured by the rotation detecting unit 204 attached to the rotating unit of the belt conveyor, and is controlled by the controller 202 based on this signal.

The quality judgment results are counted in the controller 202, and the yield, the kind of defects, etc. are statistically processed for each product and each lot and displayed on a display screen (not shown). Although the above is an example of a complete automatic inspection, it is natural that a visual inspection in which an inspector makes a quality decision and a semi-automatic inspection in which an inspector only extracts defective products are possible.

The polarization characteristics of the polyvinyl chloride film of the PTP sheet will be described in detail below. A sheet of a vinyl chloride film is generally processed by uniaxial stretching or biaxial stretching, and molecules are arranged in a stretched state in the stretching direction. The orientation of this molecule affects the polarization properties. The polarization characteristics in the stretching direction are the same before forming the pocket in the PVC film, but after forming the pocket, the polarization characteristics change at the curved surface portion of the pocket.

In FIG. 1, a polarizing filter (polarizer)
When the azimuth angle relationship between the 106 and the polarization filter (analyzer) 107 is kept at a right angle, and the incident direction of the illumination is changed around the normal line of the PTP sheet 104 while keeping the incident angle of the illumination constant, the vinyl chloride A change in contrast occurs due to the polarization characteristics of the film. In most cases, PTP sheet 10
It has been experimentally found that the highest contrast can be obtained by arranging the illumination incident direction in parallel or at right angles to the longitudinal direction of No. 4. In general, the longitudinal direction of the PTP sheet is often parallel to or perpendicular to the stretching direction.

Depending on the type of PTP sheet, the highest contrast may be obtained in addition to the above arrangement. For example, if the tablet is an ellipsoid or a rectangular parallelepiped, the shape of the pocket is not necessarily rotationally symmetric, and thus the azimuth angle at which the highest contrast is obtained changes. in this case,
While maintaining the azimuth angle relationship between the polarizing filter (polarizer) 106 and the polarizing filter (analyzer) 107 at right angles, these two polarizing filters are rotated around the optical axis to obtain the highest contrast ( Stop rotation at the optimum angle position. This initial setting work may be performed on the monitor screen or automatically by the image processing system.

In order to automatically determine the optimum angle, a motor for rotating the polarization filter (polarizer) 106 and the polarization filter (analyzer) 107 around the optical axis, and a rotary encoder for measuring the rotation angle are provided. . Attachments can be attached to the exit surface side of the optical fiber bundle 105 and the entrance surface side of the lens group 108, and only the polarization filter can be independently rotated.

For example, while keeping the relationship of the azimuth angles of the two polarization filters at a right angle, both are simultaneously rotated in the same rotation direction by 5 °, and the optimum angle is determined when the 180 ° rotation is completed. By inputting the optimum angle into the controller 202 and recording it, the same PTP will be available from the next time.
When inspecting the sheet, it is possible to save the trouble of determining the optimum angle.

FIG. 3 is an observation example of a PTP sheet by the inspection device of the present invention. In FIG. 3, polarized illumination light is applied obliquely to the PTP sheet from four directions of arrows A, A ′, B, and B ′. Of the reflected light from the PTP sheet, only polarized light of a specific azimuth angle is made incident on the imaging optical system to form an image. The aluminum foil portion 302 appeared dark and a sufficient contrast was obtained with respect to the tablet 301. Most of the reflected light from the curved surface portion of the pocket can be removed by the effect of the polarization filter of the imaging optical system. Of the reflected light from the curved surface portion of the pocket, the light having an angle of 45 ° around the normal to the edge of the PTP sheet is extremely small because it is not originally illuminated in this direction.

The angle θ (see FIG. 1) formed by the illumination light and the PTP sheet is preferably 15 ° to 30 °. If it is less than 15 °, the amount of light reflected from the PTP sheet will be insufficient,
When the angle is larger than 30 °, the reflected light from the aluminum foil is too strong, and in any case, it becomes difficult to clearly observe the contour of the tablet. In addition, PTP using a colored synthetic resin film
With respect to the sheet, the tablet could not be observed at all by the conventional method, but by using the inspection device of the present invention, it became possible to observe relatively clearly.

On the other hand, a comparative example when no polarizing filter is used will be shown. FIG. 4 is an observation example when the polarization filters of the illumination optical system and the imaging optical system are removed in the configuration of FIG. 1, and is shown for comparison with FIG. When the illumination light is applied from four directions of arrows A, A ′, B, and B ′, the aluminum foil portion 402 appears dark and a sufficient contrast with the tablet 401 is obtained. Slightly aluminum foil part 4
Only the uneven state of the surface of No. 02, especially the scattered light from the grid-like streaks formed at the time of heat bonding is observed.

However, as a drawback of this comparative example, as shown in FIG. 4, most of the reflected light 403 from the curved surface of the pocket remains, and the contour of the tablet 401 remains unclear. Next, a comparative example in which the relationship between the stretching direction of the synthetic resin film and the polarized light is ignored will be shown.

FIG. 5 is an observation example in which a polarization filter is attached to the ring illumination, a polarization filter is also attached to the front surface of the imaging lens, and the two polarization filters are installed so that the azimuth angles thereof are orthogonal to each other. Most of the specularly reflected light from the aluminum foil portion 502 is blocked by the polarizing filter. However, in the figure, the PT
Based on the outer shape of the P sheet, reflected light 503 from the pocket curved surface portion is observed at four locations in the 45 ° direction. It is considered that when the illumination light from all 360 ° directions such as ring illumination is used, there is reflected light having a polarization component that passes through the polarization filter just somewhere along the circumference of the pocket curved surface portion. In FIG. 5, there is a polarization component passing through the polarization filter on the imaging optical system side in the 45 ° direction, and it can be interpreted that this is observed as reflected light 503 from the curved surface portion. The reflected light 503 from the curved surface portion is present adjacent to the tablet 501, which is an obstacle to the inspection.

[0028]

According to the tablet inspection apparatus of the present invention, the inspection object inside the package, specifically, the presence of a tablet defect or foreign matter in the PTP sheet, can be highly accurate by increasing the contrast. And it can be detected easily. Further, the processing time can be shortened by reducing the image processing load. Furthermore, by adding a device for determining the quality of the inspection object, a device for extracting defective products, etc., a completely automatic inspection device can be obtained.

[Brief description of drawings]

FIG. 1 is a side view showing a schematic basic configuration of a tablet inspection device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a schematic configuration of a tablet inspection device according to an embodiment of the present invention.

FIG. 3 is a plan view showing an observation example of a PTP sheet according to an example of the present invention.

FIG. 4 is a plan view showing an observation example of a PTP sheet when a polarizing filter is not used, which is a comparative example with respect to the example of the present invention.

FIG. 5 is a plan view showing an observation example of a PTP sheet when a ring illumination is used, which is a comparative example with respect to the example of the present invention.

FIG. 6 is a plan view showing an observation example of a conventional PTP sheet when general illumination is used.

[Explanation of symbols]

101, 301, 401, 501, 601 ... Tablet 102, 302, 402, 502, 602 ... Aluminum foil 103 ... PVC film 104 ... PTP sheet 105 ... Optical fiber bundle 106 ... Polarizing filter (polarizer) 107 ... Polarizing filter (analyzer) 108 ... Lens group 109 ... Imaging element 403, 503, 603 ... Reflection from curved surface light

Claims (3)

[Claims] 1. A tablet inspection apparatus for inspecting an inspection object inside a package sandwiched between a metal foil and a transparent synthetic resin film having a constant stretching direction, wherein light linearly polarized by a first polarization filter is used. The two diagonal directions which are in the plane perpendicular to the synthetic resin film and which are parallel to the stretching direction, and the relative angles which are in the plane perpendicular to the synthetic resin film and which include straight lines perpendicular to the stretching direction. From at least one of the two diagonal directions
An illumination optical system for irradiating the inspection object through the synthetic resin film, and light of a predetermined polarization component of light reflected from the inspection object and the package,
An image forming optical system for forming an image through the polarizing filter of 1), and a tablet inspection apparatus. 2. The first and second polarizing filters,
Both are rotatable around the optical axis,
The tablet inspection device according to claim 1. 3. The tablet inspection apparatus according to claim 1, wherein the image forming optical system further has an image pickup device on an image forming surface.