JP3297155B2 - Liquid level detector in can - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid level detector in a can, and more particularly to an improvement of a liquid level detector in a can using X-rays.

[0002]

2. Description of the Related Art As a device for inspecting the amount of filling in various cans, a liquid level detecting device in a can using X-rays is widely used because of its quick response.

[0003] That is, in the conventional liquid level detecting device in a can, an X-ray irradiating means is arranged on one side of a continuously-filled can filled with a content liquid, and an X-ray light receiving diode array is arranged on the other side. X placed vertically and passed below the liquid level in the can
The position of the X-ray and the position of the X-ray that has passed through the head space of the can are detected, and the liquid level is judged to be appropriate (Japanese Patent Application Laid-Open No. 62-235032, Japanese Utility Model Application Laid-Open No. 59-5482).
0 etc.).

[0004]

However, it has been clarified that the conventional liquid level detecting apparatus in a can using X-rays has a problem in detection performance.

That is, as shown in FIG. 3, the can 10 moves on the belt conveyor 19 in the direction of the arrow 12, and crosses the X-ray 14 which is orthogonal to the moving direction of the can 10 and penetrates slightly above the liquid level upper limit position. The threshold level of the amount of transmission of the X-rays 14 and 16 is set using the X-ray 16 penetrating the lower limit position of the liquid surface. There is little problem in determining whether the liquid level is appropriate by judging that the liquid has passed through the lower portion, as long as the liquid level 18 in the can 10 is in a stable state.

However, there are many cases where the liquid level 18 is tilted or disturbed due to the vibration, inclination, or slight speed change of the belt conveyor 19 for transporting the cans 10.

For this reason, for example, as shown in FIG.
8 tilts back and forth with respect to the direction of can movement, X-ray 1
Depending on the irradiation positions of Nos. 4 and 16, the liquid level position is higher than the X-ray 14 and it is determined that the canning amount is excessive, even though the canned food has a normal filling amount (the irradiation positions are 14 and 16 on the left side of the figure).
16) or the liquid level is lower than the X-ray 16 and it is determined that the amount of ingestion is insufficient (the irradiation position is 1 in the right side of the figure).
4, 16).

Further, when the liquid level 18 is tilted or disturbed left and right with respect to the direction of movement of the can while the can 10 is moving in the direction perpendicular to the drawing as shown in FIG.
8 is not at a fixed level with respect to the X-ray transmission direction, and the level of the liquid surface 18 is changed from the upper end position 18a to the lower end position 1 of the liquid surface.
Since it extends over 8b, it may not be possible to detect the liquid level accurately reflecting the amount of taste.

That is, in the liquid level suitability judgment by the threshold level judgment, as shown in FIG. 5, even if the liquid level is inclined left and right with respect to the direction of movement of the can, an appropriate judgment can be made if the inclination of the liquid level is small. In some cases, when the inclination of the liquid surface is large, or when the liquid surface is distorted in a curved shape as shown in FIG. Since it is determined that the light has passed through the head space portion, an appropriate determination cannot be made in some cases.

As described above, when the liquid level 18 is tilted or disturbed in each direction, the conventional technique has a problem that it is not possible to judge the suitability based on the liquid level reflecting the amount of the in-can filling. there were.

The present invention has been made in view of the above problems, and has as its object to provide an in-can liquid level detecting apparatus capable of performing an accurate inspection of a filling amount while using X-rays having excellent responsiveness. It is in.

[0012]

In order to achieve the above-mentioned object, a liquid level detecting device in a can according to the present invention is arranged on one side of a can which is continuously conveyed and which is filled with a content liquid, and is provided inside the can. X-ray irradiating means for irradiating X-rays in the form of a sheet near the liquid surface, and an imaging device arranged to face the X-ray irradiating means with the can to be inspected interposed therebetween and for imaging the X-ray irradiating surface of the X-ray irradiating means Means for binarizing density information near a liquid surface at a constant level based on image data from the imaging means, and detecting an average value of the binarized liquid surface point data as a virtual liquid surface And determination means for determining whether the virtual liquid level obtained by the image processing means is within a predetermined range.

In the present invention, it is preferable that the imaging means is composed of an X-ray visualization panel and a CCD camera, and that the X-rays transmitted through the can are visualized and imaged by the CCD camera.

[0014]

When the liquid level in the can is disturbed or tilted in each direction, various changes occur in the X-ray transmittance near the liquid level. Therefore, the image data obtained from the image pickup means is shaded near the liquid level. And the degree of shading also changes according to the liquid level distance through which the X-ray has passed. However, the liquid level detecting device in the can according to the present invention uses the binary level of the gray level information of the image data. Liquid level is determined by the average value of the binarized liquid level point data, so that the liquid level point data is obtained with respect to the liquid level fluctuation in the X-ray irradiation direction.
Further, with respect to the liquid level fluctuation in the can transport direction, the average value of the liquid level point data accurately reflects the can filling amount, and it is possible to perform extremely accurate liquid level detection in the can.

Further, by visualizing the X-rays transmitted through the can and taking an image with a CCD camera, high-speed processing of can inspection is possible.

[0016]

FIG. 1 shows a schematic configuration of an apparatus for detecting a liquid level in a can according to this embodiment.

The in-can liquid level detecting device 100 shown in FIG.
The X-ray irradiating unit 12 includes an X-ray irradiating unit 120, an imaging unit 122, an image processing unit 124, and a determining unit 126.
The can 110 which is conveyed by the belt conveyor 119 in a direction perpendicular to the drawing is located between 0 and the imaging means 122.

An X-ray visualization panel 130 is arranged between the can 110 and the imaging means 122, and the X-ray visualization panel 130 is mounted on the back of the imaging means 122 comprising a CCD camera.
An X-ray image is obtained by imaging at.

That is, in this embodiment, the X-ray irradiating means 12
0 irradiates the X-ray over substantially the upper half of the can 110, and as a result, the imaging means 122 captures an X-ray transmission image over the substantially upper half of the can 110.

The image processing means 124 comprises a frame memory 132 and a binarization processing section 134 in this embodiment. Then, the image data of the imaging means 122 is
Are stored in the frame memory 132 as scan line information at regular intervals scanned in the vertical direction, and the density of image data is binarized at a constant level by the binarization processing unit 134 for each scan line.

The determining means 126 uses the average value of the binarized point data for each scanning line obtained by the binarization processing section 134 as a virtual liquid level, and sets the virtual liquid level position to a predetermined appropriate liquid level. It is determined whether the position is within the range of the position.

The output of the judging means 126 is instructed to the rejecting means 138, and cans out of the range of the proper liquid surface position, that is, cans with an inappropriate filling amount, are placed on the belt conveyor 119 by an arm (not shown). Is removed from the line by driving.

Next, specific data processing steps according to this embodiment will be described.

The X-ray irradiating means 120 irradiates X-rays to about the upper half where the liquid level of the can 110 will be present as described above, and the X-ray visualization panel 130 applies the X-ray to almost the upper half of the can 110. The transmission image is visualized. And CCD
The camera 122 captures an image of the X-ray visualization panel 130, and the image data is stored in the frame memory 132 in a 90-degree inverted state.

Here, as described above, the belt conveyor 1
When the liquid level in the can is inclined, for example, in the X-ray transmission direction due to the vibration of 19 or the like, the image data stored in the frame memory 132 is as shown in FIG. In the can 110 shown in FIG.
The lower part is displayed darker.

Since the X-ray transmittance is low in the wound portion 140 of the can 110 and in the portion 142 completely below the liquid level, the portion is dense.
In the complete head space portion 144, since the X-ray transmittance is relatively high, it is lightly displayed.

An inclined liquid surface portion 118 is provided between the lower liquid surface portion 142 and the head space portion 144, and the inclined liquid surface portion 118 extends both the head space and the lower liquid surface as shown in FIG. Since the line is transmitted, the gradation is displayed from the head space portion 144 to the liquid level lower portion 142 with gradation.

Then, the image data is scanned in the x direction in the figure.
It is shown like the graph of (B).

FIG. 2B shows the lightness (transmission X-ray intensity) I shown in FIG. That is,
The lightness I is maximum in the absence of the can 110, decreases significantly at the wrapped portion 140 of the can 110, increases slightly at the headspace portion 144, gradually decreases at the inclined liquid level portion 118, Under surface part 142
Is decreasing.

Here, as shown in FIG. 2B, since the inclined liquid surface portion 118 has a certain width, it is not possible to detect where the liquid surface point in the scanning line accurately reflects the amount of the can 110. .

Therefore, in the binarization processing section 134, as shown in FIG. 2B, the liquid level detection measurement range (between point a and point b) is located between the head space portion 144 and the liquid level lower portion 142.
Is set, and the lightness point in the scan line is detected by binarizing the brightness I in the liquid level detection measurement range.

That is, using the level α of the lightness I at the point a, the level β of the lightness I at the point b, and the binarization percentage in the liquid level detection measurement range, the binarization level is calculated by the following equation 1. decide.

[0033]

## EQU1 ## Binarization level = {(α-β) / 100} × (Binarization percentage) + β

The point position (c in FIG. 2B) at the binarization level in the liquid level detection measurement range is set as the liquid level point of the scan line. Assuming that the binarization percentage is, for example, 50% (usually selected from the range of 40 to 60%), an intermediate value between the level α and the level β becomes the binarization level as shown in FIG. The point c at the quantification level is detected as the liquid level point of the scan line.

It is preferable that the binarization level is calculated for each scan line using the levels α and β in the immediately preceding scan line, so that when the type of can changes, In addition, the difference in X-ray transmittance between the vicinity of the can side edge and the center of the can can be appropriately corrected. As a result, it is possible to improve the detection accuracy of the liquid level point for each scanning line and to shorten the detection time.

In this embodiment, an average value of the liquid surface point values detected for each of the scanning lines is further obtained, and the average value is determined as a virtual liquid surface of the whole liquid in the can by the judgment means 126. Is determined whether or not is at a predetermined position.

That is, when the liquid level in the can is also inclined in the can transport direction, the liquid level point value obtained by the binarization processing unit 134 is different for each scanning line. By calculating the average value of the liquid surface point values as a virtual liquid surface, it corresponds to the inclination in the can transport direction.

As described above, with respect to the inclination of the liquid level in the can in the X-ray irradiation direction, the liquid level point is calculated by the binarization processing in each scanning line, and the inclination in the can transport direction is calculated. On the other hand, since the average value of the liquid level point values is calculated and detected as the virtual liquid level, the virtual liquid level is always equal to the filling amount regardless of how the liquid level state in the can 110 is disturbed. Is accurately reflected, and highly accurate detection of the amount of flavor can be performed.

It should be noted that reference levels α and β are measured in the binarization processing section 134 in advance using cans having an appropriate filling amount, and the reference levels α and β and the levels α and β of the respective scanning lines measured in the cans to be inspected. By performing a comparison operation with β, it is possible to determine whether the container is a fully-filled can, an empty can (can not filled with the content liquid), and the like.

In this embodiment, the X-ray visualization panel (I
Since the X-ray is visualized using the (I-panel) and then imaged using a responsive CCD camera, the can liquid level inspection process can be performed at extremely high speed.

[0041]

As described above, according to the liquid level detecting apparatus in a can according to the present invention, image data near the liquid level in the can is binarized by X-rays to detect a liquid level point. Further, since the canned filling amount is inspected using the average value of the liquid surface point values as a virtual liquid surface, an accurate filling amount inspection can be performed regardless of the liquid level state in the can.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a liquid level detecting device in a can according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an image processing state by the liquid level detection device in a can shown in FIG. 1;

FIG. 3 is an explanatory view of a conventional liquid level detection mechanism in a can.

FIG. 4 is an explanatory view of a conventional liquid level detection mechanism in a can.

FIG. 5 is an explanatory view of a conventional liquid level detection mechanism in a can.

FIG. 6 is an explanatory view of a conventional liquid level detection mechanism in a can.

[Explanation of symbols]

 120 ... X-ray irradiation means 122 ... Imaging means 124 ... Image processing means 126 ... Judgment means 110 ... Can

Claims (2)

(57) [Claims] 1. An X-ray irradiating means which is arranged on one side of a continuously-conveyed can filled with a liquid and irradiates X-rays in the vicinity of a liquid surface in the can in a planar manner; An imaging unit arranged to face the X-ray irradiating unit and configured to image the X-ray irradiating surface of the X-ray irradiating unit; and based on image data from the imaging unit, the density information near the liquid level is fixed. Image processing means for detecting an average value of the binarized liquid level point data as a virtual liquid level; and determining whether or not the virtual liquid level obtained by the image processing means is within a predetermined range. A liquid level detection device in a can, comprising: a determination means. 2. An apparatus for detecting a liquid level in a can according to claim 1, wherein the imaging means comprises an X-ray visualization panel and a CCD camera, and visualizes X-rays transmitted through the can and takes an image with the CCD camera. Liquid level detector in the can.