JPH0972861A - Method and apparatus for detecting mounting abnormality of transparent film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect the mounting presence or abnormality of the resin film applied to a transparent container by heat shrinkage. SOLUTION: Two polarization plates 2, 6 rotatable vertical to a light projection axis generating an interference color by the residual strain of an applied transparent film 5 are arranged to the gap formed by opposing a white light source 1 containing the three primary colors of light and a two dimensional color image sensor 7 to each other and, when a transparent container 4 having the transparent film 5 applied thereto is passed through the gap between the polarization plates 2, 6, the interference color developed by the transparent film 5 by emitted white light is detected by the two-dimensional color image sensor 7 to measure the presence of the film or/and the edge position 11 of the film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to defects of a transparent resin film mounted on a transparent container typified by a glass bottle by heat shrinkage, specifically, the presence or absence of the film, the film tearing and wrinkles. The present invention relates to a method and an apparatus for inspecting a film mounting abnormality by detecting an oblique fog or a wave at an edge position of a film caused by the occurrence of the above phenomenon.
Further, the present invention can be applied not only to a transparent film, but also to whether or not a colored film (opaque film) which has been widely mounted and used in a transparent container has been mounted.

[0002]

2. Description of the Related Art Containers on which transparent PET bottles, glass bottles, etc., are mounted with resin films such as PVC and OPS, which have various designs due to heat shrinkage, are widely available on the market. Most of the devices developed as inspection machines for mounting height and mounting height use photoelectric sensors for opaque film mounting bottles.
For example, two sets of transmissive photoelectric sensors are arranged vertically facing each other, the light sources of the two sets of sensors project light onto the film, and the film height is inspected based on the ON / OFF output state depending on whether light is shielded or not. Was.

Recently, the number of designs of films having many transparent portions has increased, and it has become necessary to develop an inspection machine for detecting abnormalities such as mounting height and oblique fog in the films in the transparent portions. However, in the case of a transparent film, the light-shielding effect can hardly be expected, so it cannot be inspected by a conventional transmission type photoelectric sensor, and it can be detected if the wavelength of light of the projector is set to an absorption wavelength different depending on the material of the film. , For example, if the film is PVC, infrared rays with an absorption wavelength λ = 3.5 μm are required, and in the case of OPS, ultraviolet rays with an absorption wavelength λ = 350 nm are required. It is difficult to use, and it is not used as a realized inspection machine.

As a detection device for solving the above problem, FIG.
As shown in FIG. 3, when a film is attached to the transparent container 101 by thermal contraction, the light 103 is projected from the light source 104 through the two polarizing plates 105 and 106 onto the transparent film 102 having residual strain generated in the film. The light 103 (white light including the three primary colors) passing therethrough utilizes the fact that polarized light is generated due to the photoelastic effect due to residual distortion. By using a polarizing filter when receiving light on the side of the light receiver 107, A device for inspecting by improving the apparent light blocking rate has been developed.

However, in the inspection apparatus using the above-mentioned polarizing filter, since it is a one-point inspection, when the inspection is performed by passing through two films, the highest position is the uppermost position of the film. If it is the lower end, it will be judged that the lowest position is inspected, the wave and diagonal fog that are defects around the entire film edge part cannot be detected, or heat shrinkage will occur at the bonding part that is inevitable in film formation. Since it rarely occurs, it was difficult to detect a singular position that was partially raised, or because the polarization effect was weak. In addition, depending on the type of film, the polarization effect itself may not be sufficiently exerted, and in this case, there is a problem that sufficient inspection accuracy cannot be obtained. On the hardware side, the measurement error of the film position caused by the vibration of the conveyor that conveys the container to be inspected also overlaps, and although some detection can be expected, its accuracy is low and the production efficiency such as discharge of non-defective products due to misjudgment is However, it has many problems such as the fact that it cannot be used as information for pursuing and reducing the source of defects based on the detection results at the production site. It was desired to develop an inspection device.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has an abnormality in a transparent film mounted on a transparent container by heat shrinkage, that is, whether or not the film is mounted, the mounting position, and the upper and lower ends of the film. An object of the present invention is to provide a method and apparatus for accurately detecting defects such as waves and oblique fogging, and not being affected by measurement errors due to vertical vibrations of a conveyor that occurs when a container to be inspected is conveyed. To do.

[0007]

SUMMARY OF THE INVENTION The present invention, which has been made to solve the above problems, is a transparent resin mounted on the outer periphery of a transparent (including translucent) container formed of glass or resin by heat shrinkage. In a film inspection method, a white light source including three primary colors of light and a two-dimensional color image sensor are formed so as to face each other, and are perpendicular to an emission axis that generates an interference color due to residual distortion of a mounted transparent film. A two-dimensional color image of the interference color produced by arranging two rotatable polarizing plates and irradiating white light emitted by the transparent film when a transparent container equipped with a transparent film passes between the polarizing plates. By detecting with a sensor, the presence or absence of the film and / or the film edge position is measured.

In order to make the interference color an arbitrary color that makes it easy to discriminate the interference color in the above inspection method and apparatus, a quarter wavelength plate or a half wavelength plate is placed between the transparent container equipped with the transparent film and the polarizing plate on the white light source side. It is desirable to be able to install a wave plate as needed and to change the number of times the transmitted light passes through the transparent film.

Further, in the above-described inspection method and apparatus, there are at least three measurement points at the film edge position, and the measurement values are converted from the reference point of the container in which the transparent film to be inspected is mounted. Is something that
When the measured values at the three or more measured film edge positions include the measured value of the film bonded portion, the data of the film bonded portion is excluded as an abnormal value.

The above-mentioned inspection apparatus has a mechanism for calculating the central value of the data obtained by converting the film edge position measured value into the measured value from the reference point, and the central value is aggregated at an arbitrary repeating cycle. It is characterized in that it is provided with means capable of

The white light source used for the inspection may be any light source having a good balance of the three primary colors of light, and typical light sources include halogen light, white fluorescent lamp and daylight fluorescent lamp. It is desirable to use direct current lighting for these light sources in order to eliminate flicker.

[0012]

[Outline of the Invention] On the outer periphery of the body of a transparent container such as a glass bottle,
When a film made of a resin that is a little larger than the outer circumference is capped and heat-shrinked to make it adhere to the bottle outer shape, residual stress is caused by tensile stress on the film itself. Occurs. It is well known that the film has a birefringent property, that is, a photoelastic effect when white light having three primary colors of light is transmitted through the transparent film having the residual distortion.

When linearly polarized light (U) passes through the transparent film, the residual distortion causes the two vertical components (U ₁ , U ₂ ) of the linearly polarized light (U) in the film at different speeds. , And an optical path difference (phase) occurs at this time. The optical path difference between the two types of light is λ / 2 with respect to the light of wavelength λ.
When it is an even multiple of, it becomes bright by overlapping each other. While λ
When it becomes an odd multiple of / 2, they cancel each other out and become dark. That is, the light having the wavelength λ disappears.

Therefore, when the film is transmitted using a white light projector having a good balance of the three primary colors of light,
Of the three primary colors red (hereinafter "R"), green (hereinafter "G"), and blue (hereinafter "B"),
For example, when the B lights cancel each other out, the film is colored in yellow, which is the remaining mixed color of R and G. Similarly, if G cancels each other out, it becomes red-purple which is a mixed color of R and B, and if R cancels each other out, it becomes blue that is a mixed color of G and B.
The optical path difference between two types of light at a certain wavelength λ is given by the following equation. Optical path difference = photoelastic coefficient x stress x optical path length of film Here, since the photoelastic coefficient and stress can be considered to be constant, the optical path length of the film, that is, the wavelength that disappears from the short wavelength to the long wavelength disappears as the number of films increases. Move to
The color changes from yellow to magenta, blue to yellow, or an intermediate color between them. For example, as shown in FIG. 2, the hue of the color change changes depending on the number of passing films of the transmitted light.

Therefore, in the present invention, the transmitted light of these transparent films is detected by the two-dimensional color image sensor as R, G, B outputs to detect the presence of the film. The light that has passed through the bottle itself without the film is not distorted, so it is detected as a white output by being received by the color sensor as it is as white, and it is determined that there is no film. By using these, the presence or absence of the film and the edge portion of the film are identified. Then, the output of the two-dimensional color image sensor is processed by a computer, and the presence or absence of the film and the quality of the position are judged, and a sorting operation is performed. Alternatively, it is a method and apparatus that can feed back to the production line by performing trend processing on the calculated data.

[0016]

In the method and apparatus for detecting the abnormal mounting of the transparent film of the present invention thus constructed, the residual strain generated in the film when it is mounted in a transparent container due to heat shrinkage is utilized. White light is transmitted through the polarizing plate and colored by the photoelastic effect.
Since it is a method of detecting with a three-dimensional color image sensor (light receiver), when white light transmitted through a container equipped with a film passes through one film, when two films pass through, the polarization effect of The difference in color appears in each state such as when it passes through the bonded part of a small number of films, so the position of the film (presence or absence), and the front and back positions of the mounted film are determined from the color of each situation. Each can be judged.

For the purpose of further improving the detection accuracy of the color image sensor, a quarter wave plate or a half wave plate may be installed between the transparent container having the transparent film and the polarizing plate, if necessary. It can be colored in any color that can be easily determined by the sensor. Also,
As another method of giving an arbitrary color that can be easily determined by the sensor, the number of times the transmitted light passes through the transparent film can be changed (increased).

Further, the method and apparatus for detecting abnormal mounting of the transparent film according to the present invention has a structure capable of measuring at least three film edge positions. Therefore, at the time of calculating the data based on the measurement result, a specific condition can be obtained. It is possible to determine the quality of the product (film position) by excluding the data of (3) from the data of the bonded portion of the film as an abnormal value.

In addition to the measurement of the film edge position, by providing a measuring means for detecting a specific portion (for example, a bottleneck portion) serving as a reference of each container in which the film is mounted, By converting the film edge position measurement value from the reference measurement point, the film position excluding the measurement error due to the vibration of the conveyor or the like that conveys the object to be inspected can be calculated, and the quality can be determined.

Since the inspection apparatus of the present invention is provided with the trend processing mechanism capable of totalizing the data of the above-mentioned film edge position measurement results (a plurality of data is the data obtained by calculating the central value) at an arbitrary repeating cycle. By confirming the periodicity of the data, it becomes easy to grasp the tendency of occurrence of abnormality by comparing it with the number of sections of the film mounting machine or the shrinker.

The light source used in the inspection apparatus of the present invention is not limited to the material of the film, and any light source having a well-balanced three primary colors such as halogen light, white fluorescent lamp, daylight fluorescent lamp can be used. Therefore, the device itself is simple.

Although the method and apparatus for detecting the mounting abnormality of the transparent film of the present invention has been described as the apparatus for the transparent film as described above, it can be used in the same manner for the inspection of the opaque film. Therefore, it can also be applied to check the presence or absence of a mounting film.

[0023]

The present invention will be described in detail below with reference to Examples. FIG. 1 shows the basic configuration of the present invention, in which 1 is a white light source such as a halogen lamp containing the three primary colors of light in good balance, and 2 and 6 are polarizing plates which can be rotated at right angles to the projection axis. It is arranged at the position of the parallel Nicol method. Reference numeral 3 denotes a quarter-wave plate or a half-wave plate, which is provided in order to further enhance the polarization color, and is not absolutely necessary, but it is desirable to install it. 4 is a transparent glass bottle, and the transparent resin film 5 is a bottle 4 due to heat shrinkage.
It is attached closely to. The film 5 includes a bonding portion 5'in which two films are overlapped with each other in order to form a tubular shape in the manufacturing process. Reference numeral 7 denotes a camera equipped with a two-dimensional color image sensor, and the color of the light transmitted through the bottle detected by the color image sensor 7 is processed by the computer 8 such as determination output. The

The film 5 is different in thickness and material, and when the transmitted light is detected by the color sensor due to the inclination or wave (meandering) when the film is mounted, and the bonding portion 5 ', one of the films 5 is transmitted. Light,
The output of the color sensor is rich in many colors, including white, because there are two sheets, three sheets overlapped with the laminating section 5 ', or when there is no film. Accordingly, the necessary color is detected and extracted, and the presence or absence of the film or the film edge position 11 is calculated and judged by the computer 8.

The polarizing plate 2 on the projector side is preferably used at an angle inclined by 45 ° in consideration of the direction of the stress remaining in the film, and the polarizing plate 6 on the receiver side does not necessarily need to be inclined at 45 ° and is transmitted. The angle should be such that the light interferes with the film and the color is most intense.

Further, in the present invention, the film edge position 11
In order to improve the measurement accuracy of, a single reference camera 9 for detecting a specific position of each glass bottle 5 on which the film 5 is mounted, for example, the mouth 10 is installed and the mouth is measured. It has a mechanism for canceling the variation error of the film 5 due to the vibration of the conveyor when the glass bottle 4 is conveyed to the inspection position. Further, as shown in FIG. 3, by measuring the film edge position 11 at three or more positions, the wave of the film edge portion 11 caused by the oblique fog, the film tear, and the wrinkle as shown in FIG. It is configured such that a certain amount of meandering) is processed by a computer to determine whether it is good or bad, and then discharges. Furthermore,
It is also possible to remove the point-like abnormal value due to the abnormal shrinkage of the film in the laminating section 5'and perform the calculation.

The principle of the above-described film edge position measurement at multiple points and the reference camera will be described. As shown in FIG. 3, the reference camera 9 measures the top portion 10 of the glass bottle 4 on which the film 5 is mounted as l ₁ , and the film edge position 11 is measured by the measurement camera 7, for example, l _{2 to} l ₆ . The data obtained by measuring the five points is calculated by the computer 8 as shown in FIG. 3, and the quality is judged by collating it with a preset predetermined criterion. Here, the reason why the total flag is set to 2 or more is that
When the film edge position of the film laminating section 5'is measured, it is known that the film laminating section 5'has little heat shrinkage due to the laminating and the film edge position locally rises, and the data is removed. This is because. In addition, the central values of the obtained data D _{1 to} D ₅ are calculated, and the trend processing is performed in a constant cycle. For example, the vertical axis indicates the film edge position 11 and the determination standard, and the horizontal axis indicates the time (the bottle measurement order) By having a graphing function that makes it possible to plot with an arbitrary number of cycles, and from the periodicity, an abnormal value is compared with the number of heads of a shrinker or the number of labelers, for example, It is configured so that it can be determined in which process the defect has occurred.

FIGS. 5, 6 and 7 show another embodiment in which a part of the constitution of the present invention is applied, and show an outline of a method and apparatus for inspecting the presence or absence of a film. FIG. 5 shows a method for inspecting the transparent film 5 having a strong photoelastic effect, in which the white light source 1 and the camera 7 having a color sensor are inclined and opposed to each other, and the light transmitted through the film is transmitted only once. . On the other hand, in the case of a transparent film with a weak photoelastic effect,
As shown in, the number of times the polarized light is transmitted to the film is reflected by the return mirror 12 or the cat's eye to increase the coloration effect, and is detected by the camera 7 equipped with a color sensor via the half mirror 13. It is something that is done. Further, FIG. 7 shows a method of detecting by arranging the white light source 1 and the camera 7 having two sets of color sensors so as to face each other vertically, and in this case, not limited to the transparent film,
It can be applied directly to the inspection of opaque colored films.

[0029]

As described above, the method and apparatus for inspecting the mounting abnormality of the transparent film according to the present invention is such that the transparent film mounted on the transparent container by heat shrinkage is caused by the residual strain on the film when the film is mounted. The interference color of the generated polarized light is detected by a two-dimensional color image sensor, and the presence or absence of the film and the mounting position are inspected. Therefore, the light source used in the inspection device does not use a special light source. The inspection device itself has a simple structure in which it is installed by sandwiching the transport conveyor of the film mounting bottle in the production process, and its detection accuracy can be greatly improved compared to conventional inspection methods and devices. .

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of an embodiment of the present invention.

FIG. 2 is a view showing an example of a color of a film mounted on a transparent container, the film being colored by projecting polarized light.

FIG. 3 is a diagram showing an outline of measurement and calculation of a film edge position of the present invention.

FIG. 4 is a diagram showing a typical example of film defects.

FIG. 5 is a schematic diagram showing a method for inspecting the presence or absence of a film of the present invention.

FIG. 6 is a schematic view showing another inspection method of the presence or absence of a film of the present invention.

FIG. 7 is a schematic view showing another inspection method of the presence or absence of a film of the present invention.

FIG. 8 is a diagram showing an outline of a conventional example.

[Explanation of symbols]

 1 White Light Source 2 Polarizing Plate 3 Wavelength Plate 4 Transparent Container (Glass Bottle) 5 Transparent Film 6 Polarizing Plate 7 Camera with Color Sensor 8 Computer 9 Reference Camera 11 Film Edge

Claims (11)

[Claims] 1. A method for inspecting a transparent resin film, which is mounted on the outer periphery of a transparent (including semi-transparent) container made of glass or resin by heat shrinkage, and a two-dimensional white light source containing three primary colors of light. Two rotatable polarizing plates, which generate an interference color due to residual strain of the mounted transparent film, were installed between the polarizing plate and the color image sensor, and the transparent film was mounted between the polarizing plates. When a transparent container passes through, a two-dimensional color image sensor detects an interference color generated by the white light emitted due to the photoelastic effect of the transparent film, thereby inspecting the presence or absence of the film and / or the film edge position. A method for inspecting a mounting abnormality of a transparent film, which is characterized by measuring. 2. The inspection method according to claim 1, wherein a ¼ wavelength plate or a ½ wavelength plate is installed between the transparent container on which the transparent film is mounted and the polarizing plate.
The method for inspecting the mounting abnormality of the transparent film according to. 3. The transparent film according to claim 1, wherein in the inspection method according to claim 1 or 2, the number of times of transmission light passing through the transparent film can be changed. How to inspect the mounting abnormality of the. 4. The film edge position measurement points are at least three or more, and are converted into measurement values from a reference point of a container in which a transparent film to be inspected is mounted. Alternatively, the method for inspecting the mounting abnormality of the transparent film according to claim 3. 5. The film edge position has at least three measuring points, which are converted into measured values from a reference point of a container in which a transparent film to be inspected is mounted, and data at a film bonding portion is an abnormal value. The method for inspecting the mounting abnormality of the transparent film according to claim 1, claim 2, claim 3, or claim 4. 6. A transparent resin film inspection device mounted on the outer periphery of a transparent (including translucent) container formed of glass or resin by heat shrinkage, and means for irradiating a white light source containing three primary colors and 2 Two polarizing plates, which can be rotated perpendicular to the projection axis, which generate an interference color due to the residual distortion of the mounted transparent film, are installed while being formed to face a camera device having a three-dimensional color image sensor. When a transparent container equipped with a transparent film passes between the polarizing plates, the interference color produced by the photoelastic effect of the transparent film of the white light irradiated is detected by a camera device having a two-dimensional color image sensor. Thus, a transparent film mounting abnormality inspection device characterized by inspecting the presence or absence of a film and / or measuring a film edge position. 7. The inspection apparatus according to claim 6, wherein a ¼ wavelength plate or a ½ wavelength plate is installed between the transparent container on which the transparent film is mounted and the polarizing plate.
The transparent film mounting abnormality inspection device described in. 8. The inspection device according to claim 6 or 7, further comprising means capable of changing the number of times of transmission light passing through the transparent film. The transparent film mounting abnormality inspection device described. 9. A means for measuring at least three film edge position measurement points, a means for measuring a reference point of a container having a transparent film to be inspected, and a film edge position measurement value measured from the reference point. 9. A transparent film mounting abnormality inspection device according to claim 6, 7 or 8, further comprising means for converting the value into a value. 10. A means capable of measuring at least three or more film edge position measurement points, a means for measuring a reference point of a container having a transparent film to be inspected, and a film edge position measurement value measured from the reference point. A means for converting the value into a value, and a means for excluding the data of the bonded portion of the film as an abnormal value when measuring the data of the bonded portion of the film among the measurement points of the film edge position. It has, Claim 9 characterized by the above-mentioned.
The transparent film mounting abnormality inspection device described in. 11. The inspection apparatus according to claim 9 or 10, further comprising a mechanism for calculating a center value of data obtained by converting the film edge position measurement value into a measurement value from a reference point.
11. The transparent film mounting abnormality inspection device according to claim 9 or 10, further comprising means capable of totalizing the central value at an arbitrary repeating cycle.