JP2000088781A - Inspection apparatus for heat-sealed package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an inspection apparatus by which the abnormal part such as the seal defect, the pinhole or the like of a package bag can be judged without discrimination by a method wherein difference image data between measured thermal image data which is imaged by an infrared imaging device and fundamental thermal image data is compared with a prescribed threshold value and the abnormal part is judged. SOLUTION: Thermal image data which is obtained by imaging a completely heat- sealed plastic package bag by using an infrared imaging device 2 is stored in a fundamental thermal-image storage means 4 as fundamental thermal-image data. Then, measured thermal image data which is imaged by the infrared imaging device 2 and which is stored once in a measured thermal-image storage means 3 and the fundamental thermal-image data are outputted to a subtraction processing means 5 so as to perform a subtraction processing operation, and difference image data is outputted to an abnormality judgment means 6. In the abnormality judgment means 6, the difference image data is compared with a prescribed threshold value. When the difference image data is larger than the threshold value, it is judged that the heat-sealed part of the package bag is defective, an abnormality signal is outputted to a warning means 8, and the difference image data is outputted to a VTR 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat seal packaging inspection apparatus, and more particularly, to detecting an abnormality such as a defective seal in a heat seal portion of a plastic packaging bag and a pinhole generated in the plastic packaging bag. The present invention relates to a heat seal packaging inspection device capable of outputting a mark.

[0002]

2. Description of the Related Art Conventionally, for example, food packaging bags are formed of plastic. The plastic packaging bag has at least one opening, from which the content such as food is loaded, and in some cases, carbon dioxide gas is sealed together with the food, and then the opening is heat-sealed. In a sealed bag.

[0003] From the viewpoint of food safety, the food packaging bag must be a completely sealed bag, so that the heat seal portion must be completely sealed. If a food packaging bag whose heat seal is not completely sealed is found during the manufacturing process, the food packaging bag must be reliably removed from the manufacturing process as defective.

[0004] As defective packaging in a heat seal packaging bag,
For example, the case where the heat seal portion is not melt-bonded uniformly due to the non-uniform heating temperature in the heat seal portion, the case where the heat seal portion becomes wrinkled, the heating temperature is insufficient, the sealer pressure is insufficient, etc. Cases in which the heat-sealed part is not uniformly melt-bonded, poor sealing in the heat-sealed part due to loading the contents in the heat-sealed packaging bag with the heat-sealed part not completely cooled, heat-sealing due to the contents There is a case where a tear or a pinhole is generated in a part or other parts.

Conventional methods for inspecting such packaging defects include (1) a high-frequency high-voltage application method, (2) a tracer gas detection method, (3) an ultrasonic inspection method, and (4) a pressurized inspection method. (Five)
There are vacuum inspection method, (6) attenuation method of transmitted light by visible light television camera, and (7) sound wave judgment method.

The high-frequency high-voltage application method is a method of detecting a pinhole in a packaging bag by detecting a change in capacitance between a conductive substance and an insulating packaging bag. This method is not a general-purpose method because it is limited to the type of contents to be loaded in the packaging bag, and it is special because it requires a high-frequency high-voltage power supply.

The tracer gas detection method is a method in which a tracer gas is filled in a packaging bag, and a pressure is applied to the packaging bag from outside to detect a tracer gas leak with a gas detector. This method has the limitation that special tracer gases and gas detectors must be used.

In the ultrasonic detection method, a special tracer gas is not used, but a method of pressurizing a packaging bag, collecting sound of a leaking gas, and detecting the leaked gas. This method requires advanced technology for detecting delicate sounds and is not a general-purpose method. In addition, if the inspection environment is noisy or noisy, it may not be possible to perform an accurate inspection.

The pressurized inspection method is a method in which a package bag is externally pressurized and a pinhole is detected by detecting a change in the internal pressure of the package bag. This method has a problem that a special device or detector for detecting the internal pressure is required.

[0010] The vacuum inspection method is a method of putting a packaging bag in a vacuum chamber and detecting a change in the volume of the packaging bag caused by reducing the pressure in the vacuum chamber. However, this method requires a large-scale apparatus such as a vacuum chamber, and has a problem that a large number of packaging bags cannot be inspected continuously.

In the above-described transmission light attenuation method using a visible light television camera, the heat sealing portion of the packaging bag is irradiated with light, the transmitted light is detected, and the amount of change in the transmitted light amount is detected. This is a technique for finding the “sway” and “distortion” of the image. This method has a problem that it is difficult to find a pinhole.

The timbre determination method is a method of measuring a natural frequency of a metal can or the like to find a pinhole or the like. However, there is a problem that inspection targets are limited because the natural frequency of each package must be known.

As described above, the conventional inspection method or inspection apparatus has a problem that the inspection apparatus is large-scale and the inspection target is limited in spite of the large-scale inspection apparatus. Is excellent,
A problem that a pinhole can be detected, but only a "dirt" in a seal portion can be found, or conversely, a pinhole can be found, but a "dirt" cannot be detected. There is a point.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the conventional inspection apparatus. SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat seal packaging inspection apparatus capable of determining an abnormal portion in a packaging bag, for example, “snag”, “pinhole”, and the like without distinction.

[0015]

According to the present invention, there is provided an infrared imaging apparatus for imaging a plastic packaging bag, and a measurement thermal image for storing a thermal image output from the infrared imaging apparatus. Storage means, a basic thermal image storage means for storing a basic thermal image of the plastic packaging bag, and subtraction between the basic thermal image read from the basic thermal image storage means and the measured thermal image read from the measured thermal image storage means Subtraction processing means for performing processing; abnormality determination means for comparing an operation result of the subtraction processing means with a predetermined threshold to determine an abnormality; And an output unit for outputting the abnormal seal determination signal. The heat seal packaging inspection apparatus receives the abnormality judgment signal and outputs a defective product. Tic wrapping bag has a sorter to exclude from the production line.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to an embodiment of a heat seal packaging inspection apparatus according to the present invention.

As shown in FIG. 1, a heat seal packaging inspection device 1 as an example of the present invention includes an infrared imaging device 2 and
The measured thermal image storage means 3, the basic thermal image storage means 4, the subtraction processing means 5, the abnormality determination means 6, the VTR 7, the alarm means 8, the selection means 9, the recording means 10, and the operation unit (FIG. (Not shown)) and a control unit (not shown). In this example, the VTR 7 and the alarm unit 8 are output units.

An example of the infrared imaging device 2 is an imaging device which images a plastic packaging bag and outputs the obtained thermal image as a video signal. Such an infrared imaging device 2 includes, for example, a camera unit and a controller unit.

The camera section images a plastic packaging bag and outputs a temperature signal obtained according to the intensity of infrared rays radiated from the plastic packaging bag to the controller section. One specific configuration example of the camera unit having such a function includes, for example, a scanning system, an optical system, a detector, and a preamplifier. The controller unit converts the analog data output from the camera unit into digital data and stores it in a “temporary memory” in a “temporary memory”, and outputs the thermal image data sampled from the temporary memory to the measured thermal image storage unit 3 Is done.

The thermal image taken by the infrared imaging device 2 is
The image is output as a color-coded image according to the temperature distribution of the subject.

The measured thermal image storage means 3 has a frame memory for temporarily storing thermal image data output from the infrared imaging device 2.

The measured thermal image storage means 3 stores thermal image data indicating the temperature distribution in the plastic packaging bag captured by the infrared imaging device 2 as a thermal image. In order to realize this, it is also possible to cut out the image data of only the heat seal portion and its vicinity in a certain image area, and store and store the obtained cut-out image.

FIG. 2 shows an example of an image data area for obtaining image data of only the heat seal portion and its vicinity. As shown in FIG. 2, this packaging bag is formed into a tubular shape having upper and lower ends opened by overlapping the left and right ends and heat sealing the overlapped portion, heat sealing the upper end, and also forming the lower end. By heat sealing, a hermetically sealed packaging bag is created.
The image data area for the hermetically sealed packaging bag having such a heat sealing portion is the upper sealing portion 1 in this packaging bag.
1. A "horizontal H-shape" or "Katakana-shaped" including the center seal portion 12 and the lower seal portion 13. As will be described later, this image data area is appropriately determined in accordance with the shape of the heat seal portion in the sealed packaging bag.

The basic thermal image storage means 4 has a frame memory for storing, as a basic thermal image, thermal image data obtained by imaging the packaging bag completely heat-sealed by the infrared imaging device 2.

This basic thermal image storage means 4 cuts out the complete heat seal portion and image data only in the vicinity thereof in a certain image area in order to enable high-speed processing of the image data. Store and store certain thermal basic image data. It goes without saying that the basic thermal image may be not only the cutout image but also the thermal basic image data for the entire fixed image area captured by the infrared imaging device.

The subtraction processing means 5 performs a subtraction processing on the thermal image data stored in the measured thermal image storage means 3 and the basic thermal image data stored in the basic thermal image storage means 4. Is output to the abnormality determination means 6.

The abnormality judging means 6 compares the difference image data, which is the result of the subtraction, with a threshold value. For example, when it is determined that the difference image data is equal to or larger than the threshold value, an abnormality judgment signal and, if necessary, Output the difference image data.

The VTR 7 has a function of displaying an infrared image picked up by the infrared imaging device 2 so as to constantly monitor the infrared image, and a function of displaying a difference image output from the abnormality judging means 6. Switching between the infrared image and the difference image is performed according to an instruction input from the operation unit.

The alarm means 8 is configured to receive the abnormality determination signal output from the abnormality determination means 6 and emit, for example, an alarm sound or blink a warning light. The alarm means 8 is also linked with the VTR 7 to
On the screen of the TR 7, for example, the character “defective” may be blinked.

When the selection means 9 receives the abnormality determination signal output from the abnormality determination means 6, it determines that the packaging bag on the packaging line, which is imaged by the infrared imaging device 2, is defective. And has the function of removing the packaging bag from the packaging line.

The control section includes a measured thermal image storage means 3,
The control unit controls the basic thermal image storage unit 4, the subtraction processing unit 5, and the abnormality determination unit 6.

The operating section is an operating means including a keyboard and the like for performing various operations in the control section.

Incidentally, the imaging positioning means 1 shown in FIG.
Reference numeral 4 denotes a unit that detects that a subject imaged by the camera unit in the infrared imaging device 2 has entered the imaging area, and is configured by, for example, a positioning photoelectric switch. The position detection signal output from the imaging positioning means 14 is input to the positioning control means 15,
Thus, for example, the attitude of the camera unit is controlled, and the position of the camera unit is adjusted by the camera unit so that the subject is properly positioned in the imaging area. Also, as a preferred example, when the positioning control unit 15 that has received the position detection signal from the imaging positioning unit 14 determines that the subject is properly located in the imaging region, it outputs an operation command signal to the infrared imaging device and May be configured to start the imaging by.

The operation of the heat seal packaging inspection device 1 will be described below using an example in which the heat seal packaging inspection device 1 and an automatic food packaging machine are combined.

As shown in FIG. 3, the automatic food packaging machine 1
6 draws a plastic sheet from a plastic sheet roll 17 formed by winding a plastic sheet, winds the plastic sheet 18 around the peripheral side surface of a cylindrical input guide 19 into which food is charged, and forms the plastic sheet 18 on the rolled plastic sheet 18. Both ends are overlapped, and the overlapped portion is sealed by a first heating means called a center sealer 20, whereby a plastic formed in a cylindrical shape is advanced downward along the charging guide 19. The lower end of the cylindrical body is heat-sealed by a second heating means called an end-and-top sealer, and at the same time, the lower packaging bag is separated from the heat-sealed portion of the plastic cylindrical body, and at the same time, the bottom part of the packaging bag is formed. Then, the food is injected into the packaging bag through the input guide 19 together with carbon dioxide. Then, after the food was dropped, the packaging bag portion loaded with the food was lowered, and at a predetermined position, the upper portion of the packaging bag portion loaded with the food was sandwiched by the second heating means, and sealed by heat sealing. The packaging bag is completed, and the food-containing packaging bag cut off at the heat-sealed portion is sent to the conveying means.

The center sealer 20 is formed so as to be able to move toward the peripheral side surface of the loading guide 19 or to move away from the peripheral side surface. When performing heat sealing with the center sealer 20, the center sealer 20 is positioned close to the peripheral side surface of the introduction guide 19 to the extent that there is a slight gap between the center sealer 20 and the peripheral side surface of the introduction guide 19. The plastic sheet 1 is advanced while the plastic sheet 18 is advanced with both ends of the plastic sheet 18 overlapping between the center sealer 20 and the feeding guide 19.
8 can be heat-sealed at the center sealer 20 at both ends.

The end and top sealer 21, which is the second heating means, has a pair of heaters arranged opposite to each other such that a cylindrical plastic body is located therebetween. The pair of heaters are driven by appropriate driving means so as to approach and separate from each other. This pair of heaters is generally horizontally long, and is arranged horizontally in the figure. When the pair of heaters sandwich the plastic cylinder positioned between them, the inner surface of the plastic cylinder is melted and integrated by the heat of the heater to form the bottom portion of the plastic cylinder, or The upper part of the plastic cylindrical body formed with the above is fused and integrated to complete a plastic packaging bag.

The camera section of the infrared imaging device 2 which is an element of the heat seal packaging inspection device 1 which is one embodiment of the present invention captures an image of a packaging bag suspended below the end and top sealer 21. So that
Be placed.

In this example, the photographing area of the packaging bag which is imaged by the camera section is the entire front surface of the packaging bag having the heat seal portion. In some cases, it may be a part of the heat seal part and the vicinity of the heat seal part.

Here, the packaging bag has a broad concept including not only a so-called bag but also a box. Therefore, the shape of the heat seal portion in the packaging bag varies. The packaging bag shown in FIG. 2 has a center seal portion formed by rolling a sheet and heat-sealing both overlapping ends,
An upper seal portion formed by heat-sealing and sealing the upper end opening of the cylindrical body formed into a cylindrical shape by heat sealing both ends, and heat sealing the lower end opening of the cylindrical body. And a heat seal portion including a lower seal portion formed by fusing. When the package bag is viewed from the center seal portion side, the heat seal portion becomes “H-shaped sideways” or “Katakana-shaped”, and when the package bag is viewed from the side opposite to the center seal portion, the heat seal portion is formed. The part is "two parallel streaks". In addition to the above-described heat seal portions, there are various types of heat seal portions depending on the structure of the packaging bag. However, the present invention can be applied to any form of heat seal portion.

This camera section, as shown in FIG.
It may be arranged or configured to be able to image the entire front of the packaging bag, and although not shown,
It is arranged so that a part of the center seal part of the packaging bag and the lower seal part and the vicinity thereof can be imaged,
Or you may comprise.

Further, the camera unit may not only image the front of the packaging bag but also simultaneously image the front and back of the packaging bag. In order to simultaneously image the front and back of the packaging bag, as shown in FIG. 4, a reflection mirror (mirror) 22 is arranged on the back side of the packaging bag, and the front and back of the packaging bag and the reflection mirror 22 are projected. The positional relationship between the camera unit and the reflecting mirror 22 is adjusted so that the back surface of the packaging bag can be imaged simultaneously,
Good to place them.

In FIG. 4, reference numeral 23 denotes a camera unit.

The camera section only needs to be able to detect the temperature of the subject and obtain an image as the temperature distribution. Therefore, the camera section does not need to be a high-performance camera capable of capturing a high-resolution image. Infrared camera can be adopted. As an example of the performance of the camera unit, for example, the temperature resolution is 0.2 ° C., the number of effective pixels is 210,000 pixels, the field time is, for example, 1/60 second,
Horizontal resolution 0.3 when the focal length is 0.5m
6 mm × 0.27 mm vertical / pixel. In short, the object of the present invention can be sufficiently achieved without providing a high-performance camera unit with high resolution.

It is assumed that the imaging area of the packaging bag by the camera section is the “side-down H-shaped” heat seal section as shown in FIG. 2 and its vicinity. In this case, an image signal is output to the measured thermal image storage means 3 by the camera section imaging the front of the packaging bag.

In order to increase the image processing speed, the measured thermal image storage means 3 cuts out measured thermal image data corresponding to a predetermined heat seal portion and a limited area in the vicinity thereof, that is, a limited frame, and stores this. Remember. FIG. 6 shows an example of a measured thermal image covering the entire front surface of the packaging bag including the heat seal portion in order to detect a defective portion in the entire packaging bag without the necessity of increasing the image processing speed vigorously. It is.

As shown in FIG. 6, if the imaged heat seal portion has a twisted portion, for example, the measured thermal image including the twisted portion includes an image portion 24 different from the complete heat sealed portion. Similarly, if, for example, a pinhole is present in the imaged heat seal portion, the measured thermal image including the pinhole includes an image portion 25 different from the complete heat seal portion.

On the other hand, the basic image storage means stores a basic thermal image 26 obtained by imaging a complete heat seal portion having no abnormal seal portion such as a pinhole or a twisted portion.

Then, the measured thermal image data captured by the infrared imaging device 2 and the basic image data stored in the basic image storage means are output to the subtraction processing means 5.

The subtraction processing means 5 subtracts the basic image data from the input measured thermal image data. Note that the measured thermal image data may be subtracted from the basic image data. When the subtraction processing is performed, as shown in FIG. 6, a distorted portion or a pinhole is obtained as difference images 27a and 27b.

The difference image data is output to the abnormality judging means 6, and the abnormality judging means 6 compares the difference image data with a predetermined threshold value. If the difference image data is judged to be larger than the threshold value, Is determined to be defective, the abnormality determination signal is output to the alarm means 8, and the difference image data is output to the VTR 7.

When the abnormality determination signal is inputted to the alarm means 8, an alarm is issued by appropriately using visual means or auditory means. The VTR 7 displays a difference image as shown in FIG. 6 on the screen.

In a packaging bag for packaging food, the occurrence of pinholes must be absolutely avoided at any site, not limited to the heat-sealed portion.

Therefore, pinholes in the heat seal portion or in portions other than the heat seal portion must be detected more strictly than in the twisted portion. In order to reliably detect the pinhole, it is preferable to use not only the subtraction processing of the measured thermal image and the basic thermal image but also the following method.

That is, in preparing the packaging bag, an infrared-absorbing gas such as water vapor or carbon dioxide gas is mixed into the packaging bag as a content, and as shown in FIG. The packaging bag is pressed by the pressure arm 28 (see FIG. 4). Then, when a pinhole is generated in the heat seal portion, the internal gas is ejected from the pinhole portion. When this ejected gas is imaged by the infrared imaging device 2, it becomes an image in which infrared rays are absorbed. Therefore, when the subtraction processing means 5 performs a subtraction process on the measured thermal image and the basic thermal image, a portion having a pinhole appears as an enhanced image. This makes it possible to reliably detect the occurrence of a pinhole.

The VTR 7 can display not only a difference image but also a measured thermal image taken by the infrared imaging device 2 with time. The recording means 10 stores the detected difference image as a record.

The abnormality judgment signal output from the abnormality judgment means 6 is also output to the selection means 9. The sorting means 9 operates so as to exclude the packaging bag determined to be abnormal from the packaging process line.

As the sorting means 9, various types and structures of machines can be appropriately used. The sorting means 9 is interlocked with the abnormality judging means 6 and receives an abnormality judging signal output from the abnormality judging means 6. As long as the device has a mechanism capable of removing a packaging bag determined to be defective from the packaging process, various device configurations can be adopted.

In the above, the heat seal packaging inspection apparatus 1 according to one embodiment of the present invention has been described. However, the present invention is not limited to the heat seal packaging inspection apparatus 1 described above.

The above-described heat seal packaging inspection apparatus 1 is applied to a so-called vertical pillow packaging machine, but can also be applied to a horizontal pillow packaging machine.

FIG. 7 is an explanatory view in which the horizontal pillow packaging machine and the heat seal packaging inspection device 1 are combined.

As shown in FIG. 7, in the horizontal pillow packaging machine 29, a packaging bag having the same heat seal portion as that in the vertical pillow packaging machine is formed, and after the heat sealing, the packaging bag is transferred to a belt conveyor or the like. It is conveyed by the means 30. Belt conveyor, heat seal packaging inspection device 1
The packaging bag 31 is transported to the heat seal packaging inspection device 1 by a belt conveyor. The imaging position of the transported packaging bag 31 is confirmed by the imaging positioning means (not shown in FIG. 7) of the packaging bag 31, and the camera unit 23 in the infrared imaging device 2 captures an image of the packaging bag 31.

The processing for the captured measurement image is the same as that in the case of the combination of the vertical pillow packaging machine and the heat seal packaging inspection apparatus 1.

[0064]

According to the present invention, the image of the heat-sealed packaging bag taken by the infrared imaging device is processed.
It is possible to detect non-uniform sealing state due to poor heating in the heat seal part, to detect that water or other foreign matter is mixed in the heat seal part, and to detect poor heat welding in the multilayer seal part and its bent edge part. Can be detected.

By sealing the infrared-absorbing gas in the packaging bag, pinholes in the vicinity of the heat-sealed portion or other than the heat-sealed portion can be detected. That is, the heat seal packaging inspection device can reliably detect not only a seal abnormality in the heat seal portion but also a pinhole generated in a region other than the heat seal portion.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a heat seal packaging inspection apparatus according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating an area of a subject imaged by an infrared imaging device;

FIG. 3 is an explanatory diagram showing a state in which a pillow packaging bag is created by a vertical pillow packaging machine.

FIG. 4 is an explanatory diagram showing a state in which a pillow packaging bag is created by a vertical pillow packaging machine.

FIG. 5 is an explanatory view showing a state in which a pillow packaging bag is created by a vertical pillow packaging machine.

FIG. 6 is an explanatory diagram illustrating the principle of a subtraction process between a measured thermal image and a basic thermal image.

FIG. 7 is an explanatory diagram showing a combination of a horizontal pillow packaging machine and a heat seal packaging inspection device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Heat seal packaging inspection device, 2 ... Infrared imaging device, 3 ... Measurement thermal image storage means, 4 ... Basic thermal image storage means, 5 ... Subtraction processing means, 6 ... Abnormality judging means, 7 VTR, 8 alarm means, 9 sorting means, 10 recording means, 11 upper seal part,
12: Center seal part, 13: Lower seal part, 14: Imaging positioning means, 15: Positioning control means, 16: Automatic packaging machine, 17: Plastic sheet roll, 18 ..Plastic sheets, 1
9: loading guide, 20: center sealer, 2
DESCRIPTION OF SYMBOLS 1 ... End and top sealer, 22 ... Reflecting mirror, 23 ... Camera part, 24 ... Image part, 25
..Image portion, 26 ... Basic thermal image, 27a, 27b
... difference image, 28 ... pressure arm, 29 ... horizontal pillow packaging machine, 30 ... conveyance means, 31 ... packaging bag.

Claims (2)

[Claims] 1. An infrared imaging device for imaging a plastic packaging bag, a measurement thermal image storage means for storing a thermal image output from the infrared imaging device, and a basic thermal image for storing a basic thermal image of the plastic packaging bag. Image storage means, subtraction processing means for performing subtraction processing between the basic thermal image read from the basic thermal image storage means and the measurement thermal image read from the measurement thermal image storage means, and a calculation result in the subtraction processing means A heat seal comprising: an abnormality determination unit that determines an abnormality by comparing the abnormality with a predetermined threshold value; and an output unit that receives an abnormality determination signal output from the abnormality determination unit and outputs an abnormality result. Packaging inspection equipment. 2. The heat seal packaging inspection apparatus according to claim 1, further comprising a sorting machine that receives the abnormality determination signal and removes a plastic packaging bag regarded as a defective product from a production line.