JP3976961B2 - Appearance inspection method for goods - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention, the appearance of the long circle (ellipse) shape of the article, to a method for inspecting the example of contour and surface abnormality.
[0002]
[Prior art]
Conventionally, an appearance inspection of an article has been performed by visual inspection. However, recently, an inspection apparatus using image processing has been used due to problems such as inspection cost and accuracy. In general, an appearance inspection method using image processing is a method in which the surface of an article is first imaged with a camera, and the contrast of each pixel of the image is set to a preset threshold value (generally one value classified into 256 gradations). ) And binarized, and for example, the number of pixels determined to be dark is calculated from the result, thereby inspecting defective products.
[0003]
By the way, in the case of a tablet, for example, the surface may be printed with characters or the like having a contrast different from that of other surfaces. There is a problem that a defect having a lower contrast (high brightness) cannot be detected.
[0004]
Japanese Patent Laid-Open No. 4-36643 proposes the following apparatus. That is, the imaged area is divided into a plurality of areas in accordance with the contrast, and each divided area is binarized by a predetermined threshold value set in advance, and comprehensively determined from the result. .
[0005]
[Problems to be solved by the invention]
However, in the case of this apparatus, it is difficult to divide the imaged area into a plurality of areas according to the contrast, and it is complicated. If a threshold value is determined in order to perform a high-precision inspection, an error will occur. This may cause detection and cause a failure in use on the actual line. In addition, when the object to be inspected is an oval or elliptical article, since it is usually directed in various directions by rotating, the process of rotating pattern matching is almost impossible in terms of time.
[0006]
An object of the present invention is to provide an appearance inspection method for an article that can perform a stable inspection even when a high-precision inspection is performed.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the present invention employs the following means.
That is, the present invention is an appearance inspection method for an ellipse-shaped article, in which an image capturing process for inputting an image of the article, a Sobel process for extracting the outer shape of the article, and a sobel-processed article image are performed. Edge detection processing that detects multiple edges by multiple line searches, processing to calculate the midpoint between two points of the same straight edge obtained by edge detection processing, and calculating a straight line that passes through these midpoints , A process for calculating the major axis dimension of the article from the intersection of the straight line and the outer shape of the article image, a process for calculating coordinates obtained by equally dividing the major axis center line, and the same diameter as the minor axis dimension of the article image This is characterized in that the center of the article is aligned with the division coordinates and the appearance of the article is inspected by searching from the long axis end of the article image to the opposite end.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In addition, embodiment shown below is an example at the time of applying to the test | inspection of an oval-shaped capsule.
[0009]
FIG. 1 is a flowchart showing an embodiment of the present invention.
In general, the appearance inspection of tablets and capsules is performed by aligning and inspecting an object to be inspected on a conveyor, picking it up with a camera, and performing image processing with an image processing apparatus to determine whether the appearance is good or bad. . In the case of a PTP-packed drug, a drug such as a tablet or a capsule is put into a recess formed on a transparent plastic plate, and an aluminum foil is attached thereon to enclose the drug. Therefore, when the appearance of the medicine in the recess is inspected when the aluminum foil is not yet applied, it is convenient because the positions are aligned.
[0010]
In this embodiment, the image processing apparatus is used as in the prior art, but has a feature in the inspection processing method. As shown in FIG. 1 , first, in step S <b> 21, an image capturing process is performed by illuminating the capsule placed in the concave portion of the transparent plastic plate from the back side and imaging with a camera.
[0011]
Subsequently, it is determined whether or not the illuminance of the captured image is appropriate (S22). If the illuminance is not appropriate, the determination in the subsequent processing becomes inaccurate, so the progress of the inspection process is stopped (NG4). In this case, adjustment of the lighting device is required.
[0012]
If the illuminance is appropriate, the presence or absence of the capsule is confirmed (S23). When there is no tablet, it is a defective product, so the progress of the inspection process is stopped (NG3). If a capsule is contained, the image is subjected to Sobel processing (S24). When the Sobel process is performed, the outer shape B of the capsule is extracted and becomes as shown in FIG .
[0013]
Next, the inclination and length of the capsule are measured (S25). For this purpose, as shown in FIG. 2A, the edges of the Sobel-processed capsule image are searched and detected by two parallel straight lines N (two in this example, but two or more). .
[0014]
Next, as shown in FIG. 2B, midpoints O1 and O2 between two points of the same straight edges K1, K2, K3, and K4 obtained by the edge detection process are respectively calculated.
[0015]
Subsequently, as shown in FIG. 2 (c), a straight line J passing through these midpoints is calculated, and the major axis dimension (J1-J2) of the capsule is calculated from the intersection of this straight line and the outer edge of the capsule image. (See FIG. 2 (d)).
[0016]
Here, it is determined whether or not the length of the capsule is appropriate (S26), and if it is a defective product, it is excluded (NG2). If the length of the capsule is appropriate, a coordinate J3 obtained by equally dividing the long axis center line in S27 is calculated (see FIG. 2 (e)).
[0017]
Subsequently, as shown in FIG. 3 , a circle having the same diameter as the minor axis dimension of the capsule is centered on the division coordinate J3 and searched from the major axis end to the opposite end of the capsule. The appearance (in this case, the outer shape) of the agent is inspected (S27). If there is an abnormality such as a dent in the outer shape (S28), it is determined as a defective product (NG1). As a specific determination method, for example, each pixel on the searched circle is compared with a preset threshold value, and pixels out of the preset threshold value in one circular search are detected. A certain circle is stored as “pixel defective”. From these results, a final pass / fail judgment is made based on a predetermined range, for example, a defective product if 10 are continued or a defective product if there are many defective pixels.
[0018]
In this way, in this inspection method, first, the length of the capsule is inspected to determine whether it is good or bad, and then the capsule is searched from end to end while shifting the position of the circle at regular intervals to inspect the outer shape. I will do it. For this reason, stable inspection can be performed even when high-precision inspection is performed.
[0019]
In the above embodiment showed the appearance inspection method for drugs, not limited to this and can be adapted if visual inspection of the articles of the oval (including elliptical).
[0020]
【The invention's effect】
As described above, according to the present invention, it is possible to set many pass / fail judgment criteria such as the number and length of detections on individual circular searches, continuity of search judgment results, etc., so that final defect judgment can be performed. Stable inspection is possible even when high-precision inspection is performed. In addition, since no area measurement or the like is performed, all multi-value image processing can be performed, so that further improvement in detection accuracy can be obtained.
[0021]
In addition, even when the object is an oval or elliptical article, a circular search can be continuously performed in accordance with the rotation angle, so that pseudo rotation pattern matching can be realized at high speed.
[Brief description of the drawings]
FIG. 1 is a flowchart of an embodiment of the present invention.
FIG. 2 is a diagram for explaining the measurement of the inclination and length of a capsule and equally dividing the length.
FIG. 3 is a diagram showing a capsule inspection search method.
[Explanation of symbols]
B Capsule after sobel processing

Claims (1)

An appearance inspection method for an oval shaped article, which is a video capture process for inputting an image of an article, a Sobel process for extracting the outline of the article, and a plurality of straight lines for edges of the Sobel processed article image. Edge detection processing detected by search, processing for calculating a midpoint between two edges of the same straight line obtained by the edge detection processing, and calculating a straight line passing through these midpoints. The process of calculating the major axis dimension of the article from the intersection with the outer shape of the article, the process of calculating coordinates obtained by dividing the major axis center line equally, and the center of the circle with the same diameter as the minor axis dimension of the article video A method for inspecting the appearance of an article, wherein the appearance of the article is inspected by searching from the major axis end of the article image to the opposite end in accordance with the division coordinates.

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