JP7109020B2 - Package product inspection device and inspection method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an inspection apparatus and inspection method for a packaged product, which is a product in which contents are contained in a container, and in particular, covers a container body and an opening for exposing the contents by opening the inside of the package. It is suitable for inspecting the presence or absence of sealing defects in the sealing portion with the lid.

In the sealing portion where the container body and the lid are adhered by heat sealing or the like, the contents or a part thereof may be interposed, resulting in poor sealing. Poor seals impede the sealing performance of packages, resulting in quality deterioration and food spoilage. Therefore, inspections are performed before shipment to ensure that packages with poor seals are eliminated. It must be.

Techniques disclosed in Patent Literature 1 and Patent Literature 2 can be used as techniques for detecting seal failure. In Patent Document 1, a heat change is applied from the outside to the packaging material of a product in which food is packaged, and the temperature difference caused by the heat capacity of the part where the content is attached is different from that of other parts. ) has been disclosed, and this technology is said to be applicable to inspection of adhesion of contents to the seal portion. In addition, in Patent Document 2, mainly, a package product at a uniform first temperature is exposed to a second temperature condition different from the first temperature, and after that, heat conduction from the contents and radiant heat transfer A technique is disclosed for inspecting at least one of the shape, size, and number of contents based on the surface temperature distribution of the packaging material. In addition, by applying this technology and determining the position of the contents with respect to the packaging material, it is possible to inspect whether or not the contents are caught in the sealed portion. is also described.

JP-A-62-28650 Japanese Patent Application No. 2017-053549

The present invention further improves the techniques disclosed in these patent documents, and has a configuration that enables high-speed inspection of mass-produced packaged products, and enables accurate detection of sealing defects in packaged products. intended to

To this end, the present invention includes a container body having an opening for storing contents and exposing the contents, and a lid sealed to the container body so as to close the opening. An inspection device for a packaged product,
a conveying means for conveying the package at a first temperature;
heat applying means for changing the lid to a second temperature different from the first temperature in the course of the transportation;
detection means for capturing a thermographic image representing the surface temperature distribution of the lid using an infrared camera, and detecting a defect in a sealing portion between the container body and the lid based on the thermographic image;
with
The conveying surface is configured to exhibit a third temperature at which a boundary between the contour of the lid and the conveying surface of the conveying means clearly appears in the thermographic image.

Further, the present invention includes a container body having an opening for storing contents and exposing the contents, and a lid sealed to the container body so as to close the opening. An inspection method for inspecting a package product at a first temperature while being transported by a transport means,
a heat applying step of changing the lid to a second temperature different from the first temperature using heat applying means;
an adjusting step of adjusting the conveying surface of the conveying means to exhibit a third temperature;
a detection step of capturing a thermographic image representing the distribution of the surface temperature of the lid using an infrared camera, and detecting a defect in a sealing portion where the container body and the lid are bonded based on the thermographic image;
and wherein the third temperature adjusted in the adjustment step is a temperature at which a boundary between the outline of the lid and the conveying surface appears clearly in the thermographic image.

According to the present invention, the boundary between the outline of the lid and the conveying surface of the conveying means appears clearly in the image, so that the image of the sealed portion can be accurately extracted, and the presence or absence of a seal defect and its position can be specified. Become.

It is a schematic diagram for demonstrating the principle of this invention which detects a sealing failure. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a first embodiment of a package product inspection method or apparatus; FIG. 2 is a schematic diagram showing a second embodiment of a package product inspection method or apparatus; FIG. 10 is a schematic diagram showing a third embodiment of a package product inspection method or apparatus; It is a schematic diagram for demonstrating the principle which detects a sealing failure more correctly. FIG. 10 is a schematic diagram showing a fourth embodiment of a package product inspection method or apparatus;

The present invention will now be described in detail with reference to the drawings.

(Inspection object of the present invention)
A package product that can be inspected by the present invention is composed of a container body that contains contents and a lid that covers the opening of the container body. and are adhered by heat sealing or the like to form a seal portion that seals the inside of the packaged product.

Examples of materials for the container body include foamed or non-foamed plastics, papers, aluminum, and aluminum laminates. In addition, the lid can be formed of, for example, plastic, paper, or a cap seal obtained by laminating these and aluminum foil, but not limited to these, particularly visible light and infrared rays. The present invention can be effectively applied to impermeable objects. The form of the contents includes solids, fluids, and mixtures thereof, and the types include foods such as noodles, jelly, pudding, and beverages, but are not limited to these.

Packaged goods to which the present invention can be applied include, for example, cup noodles. In general, cup noodles contain dried noodles, additives, and a plastic bag containing powdered or liquid soup as contents, and a container body made of foamed polystyrene or the like having an opening on the top, and the entire opening and a lid formed of an aluminum laminate film or the like that covers the The opening of the container body extends over the entire upper surface, so that peripheral edges of the container body and the lid are adhered to each other to form a seal.

When filling the container body with the contents, the contents or part thereof (dried noodle pieces, additives, edges and corners of plastic bags, etc.) are located (bitten) at the periphery of the container body. If the sealing is performed as it is, a sealing failure will occur. Therefore, it is important to inspect the presence or absence of entrapment in the sealing portion. In the following description, the contents located in the seal portion (actually caught between the container body and the lid) or part thereof will be referred to as "foreign matter" for the sake of convenience, although they are not foreign objects. A portion of the seal portion where foreign matter is present is called a "foreign matter present portion", and a portion where no foreign matter is present is called a "foreign matter nonexisting portion".

(Basic principle of the present invention)
FIG. 1 is a schematic plan view showing the transport state of the packaged product during inspection. Here, the packaged product 1 in the form of cup noodles is transported in the direction of arrow F by an endless conveyor belt 21. is shown. The container body of the packaged product 1 is made of foamed polystyrene or the like, which has a smaller heat capacity and lower thermal conductivity than the foreign matter caught in it. is blocked. The portion where the peripheral edges of the container body and the lid 3 are bonded to each other (the annular portion between the outer circle indicated by the solid line and the inner circle indicated by the broken line) serves as the seal portion 5. Foreign matter 7 may be present in 5 . In reality, there are cases in which a knob for removing the lid is provided, and cases in which the outline of the lid 3 protrudes outside the sealing portion, but in FIG. 5 coincides with the contour of the lid 3 indicated by the solid circle. However, in any case, if the outline of the lid 3 is clearly identified, the shape of the seal portion 5 inside it can also be estimated.

The inspection is performed by a heat applying device and an infrared camera (both described later) that are arranged along the transport direction F so as to face the transport belt 21 . For example, before the inspection, the package 1, which is at a uniform first temperature (environmental temperature, etc.) T1, is transported in the F direction, and the lid 3, which is the portion to be observed for presence or absence of jamming, is heated to the first temperature by a heat applying device. The temperature is changed to a second temperature T2 different from T1, and based on the distribution of the surface temperature of the lid 3 after that, the presence or absence and the position of the foreign matter 7 that causes the sealing failure is detected. The heat imparting device consists of a heating means that heats the part of the package to be inspected by radiant heat transfer or convection heat transfer, and a cooling means that cools the part by applying cold air or cold air to the part by convection heat transfer. , can be either.

When the first temperature T1<the second temperature T2, that is, when the heat applying device is the heating means, by being heated by the heating means, the non-existing foreign matter portion having a small heat capacity responds sensitively to the temperature change, and While it is heated to the second temperature T2 (or a temperature close to it) in time, the foreign matter existing portion has a large heat capacity, so the temperature rises slowly. Further, when the first temperature T1>the second temperature T2, that is, when the heat applying device is used as the cooling means, the non-existing foreign matter portion is cooled to the second temperature T2 (or a temperature close thereto) in a short period of time. On the other hand, the temperature drop at the foreign matter existing portion is slow. Therefore, if the second temperature T2 and the heat application period are set so that a significant temperature difference is generated between the foreign matter present portion and the foreign matter absent portion at the time of imaging by the infrared camera, the heat applying device serves as the heating means. By observing the temperature distribution based on the thermographic image, it becomes possible to identify the presence or absence of the foreign matter 7 or the defective seal and the position of occurrence of the foreign matter 7 or the cooling means.

However, in order to inspect mass-produced packaged products at high speed, the present inventors inspected the packaged products while conveying them to an inspection area in which the heat applying means and the infrared camera are arranged in this order. was found to be unable to accurately detect seal failures. As a result of investigations by the present inventors, it was confirmed that the temperature of the conveying surface of conveying means such as a conveying belt for conveying packages (hereinafter also referred to as background temperature) affects the detection accuracy. This will be explained concretely.

While the package 1 is led out of the inspection area after the inspection, the conveying belt 21 changes from the temperature (for example, the first temperature T1, which is the environmental temperature) before the start of a series of inspections to the circulation during the inspection. while being continuously exposed to the heat application device. Therefore, when the heat applying device is the heating means, the temperature of the conveying belt 21 increases as the inspection continues, and approaches the second temperature T2. At the time of imaging, if the conveying belt 21 exhibits a temperature in the vicinity of the annular region along the contour of the lid 3 or the seal portion 5 (particularly, the foreign matter-free portion that occupies the majority of the annular portion), the contour of the lid 3, for example, If the temperature difference between the seal portion 5 and the conveyor belt 21 is within a predetermined range (for example, within 3 degrees), the boundary between the two (outline of the lid 3) becomes unclear in the thermographic image, and the foreign matter 7 or the seal Defect detection accuracy decreases. In addition, the temperature rise of the conveyor belt 21 is not uniform due to the transportation position and the transportation density of the packages 1 on the conveyor belt 21, and temperature unevenness occurs. Stable inspection is no longer guaranteed.

On the other hand, if the heat application device is a cooling means, the conveying belt 21 is constantly cooled while circulating, so the temperature of the conveying belt 21 decreases as the inspection continues, and approaches the temperature of the seal portion 5 at the time of imaging. become. Then, as in the case of heating, problems may occur due to unclear observation of the outline of the lid 3 and thus the sealing portion 5 and uneven temperature of the conveying belt 21 .

Accordingly, the present invention provides a configuration capable of accurately detecting the foreign matter 7 while being capable of inspecting mass-produced packaged products at high speed. Several embodiments thereof will be described below.

(First embodiment)
FIG. 2 is a schematic diagram showing a first embodiment of a package product inspection apparatus to which the basic principle of the present invention is applied.

Assume that the package 1 is initially exposed to an ambient temperature, which is the first temperature T1, so that the package 1 exhibits a uniform temperature T1 as a whole. Here, the environmental temperature may be, for example, the environmental temperature of the storage location of the manufactured package 1 . The package 1 is conveyed by conveying means having the form of a belt conveyor 20 consisting of an endless conveying belt 21 stretched over a pair of rollers 23 and 25 arranged upstream and downstream in the conveying direction F. be done. As the conveying means, a group of rollers arranged side by side in the conveying direction may be used.

A heat applying device 30 and an infrared camera 40 are arranged on the upstream side and the downstream side in the conveying direction F, respectively, facing the conveying surface of the conveying belt 21 . The heat application device 30 is means for causing a temperature change from the first temperature T1 to the second temperature T2 in the lid 3 of the package 1, and applies heat by radiant heat transfer or convective heat transfer. In order to obtain a preferable temperature difference between the first temperature T1 and the second temperature T2, the first temperature T1 may be detected and the second temperature T2 may be changed accordingly. An infrared image (thermographic image) of the package 1 that has passed through the area facing the heat application device 30 is captured by the infrared camera 40, and the package 1 is inspected by the inspection unit 50 based on the temperature distribution appearing in the image. done.

When the temperature of the packaged product 1 is to be changed by radiant heat transfer, a heat imparting device 30 that radiates mid- to far-infrared rays is used. When the temperature is to be changed by convective heat transfer, a heat imparting device 30 is used to bring the package 1 into contact with air at a temperature that changes the lid 3 to the second temperature T2. It is possible to form a combination of an element and a blower that blows air at a temperature that changes the lid 3 to the second temperature T2 to the package 1 or a chamber that allows the package 1 to pass through. On the other hand, as the infrared camera 40, a camera sensitive to far infrared rays including wavelengths of 7 to 14 μm can be used.

The use of far infrared rays has the following advantages. The cover 3 of the packaged product 1 may be printed to display the product name, illustration, etc. The darker the color of the print, the more difficult it is for near-infrared rays to pass through, making it difficult to identify the outline of the cover 3. Therefore, when using the heat application device 30 by radiant heat transfer, it is advantageous to use far-infrared rays, which are more likely to pass through printing than near-infrared rays. In addition, a configuration using a far-infrared irradiation device (heat applying device 30) or an imaging device (camera 40) can generally be made smaller and cheaper than a configuration using near-infrared rays. There are advantages to be had.

As described above, the temperature of the conveyor belt 21 may change as the inspection continues. Therefore, for the belt conveyor 20, for example, on the opposite side of the conveying surface, means for adjusting the conveying belt 21 so that the temperature does not become unfavorable. A blower 60 is arranged as a temperature adjusting means for adjusting the temperature so that the conveying surface of the conveying belt 21 exhibits a third temperature at which the boundary of . The blower 60 blows cold air when heating the package 1 (T1<T2), and blows warm air when cooling (T1>T2).

The operation of the blower 60 is controlled by the inspection unit 50, which is detection means. That is, the inspection unit 50 observes the temperature (background temperature) of the conveying surface of the conveying belt 21 or the temperature difference between the background temperature and the temperature of the seal portion 5 based on the thermographic image. If it is in the vicinity, the blower 60 is operated to maintain the third temperature T3 at which the outline of the lid 3 appears clearly in the thermographic image. According to this, the outline of the lid 3 can be clearly identified while the packaged goods 1 are conveyed at high speed. Since the width of the annular seal portion 5 shown in FIG. 1 is determined by the package 1, if the outline can be clearly identified, the image of the seal portion can be extracted to detect the foreign matter 7 or seal failure with high accuracy. becomes possible.

It is also possible to separately provide temperature detection means for monitoring the temperature of the conveying belt 21 and turn on/off the blower 60 based on the detected temperature. However, the use of the inspection unit 50 is advantageous because it simplifies the construction of the inspection apparatus.

(Second embodiment)
FIG. 3 is a schematic diagram showing a package product inspection apparatus according to a second embodiment of the present invention. In the first embodiment, a single belt conveyor 20 is used as a conveying system for the package 1 with respect to the heat applying device 30 and the infrared camera 40 . On the other hand, in the present embodiment, the belt conveyor 20A, which is the conveying means on the upstream side in the conveying direction for conveying the package 1 to the heat application device 30, 1 and the belt conveyor 20B, which is a conveying means on the downstream side in the conveying direction.

In the first embodiment, depending on the length or running speed of the conveyor belt 21, the blower 60 alone may not be sufficient to suppress undesirable temperature changes in the conveyor belt 21 and to eliminate temperature unevenness. . On the other hand, in the present embodiment, the belt conveyor 20B is insulated from the heat application device 30, so the temperature distribution can be observed while mitigating the problems caused by the temperature change.

However, in this embodiment, as a further development, the temperature of the conveyor belt 21A and the conveyor belt 21B is adjusted with respect to the belt conveyor 20A and the belt conveyor 20B, respectively. A temperature adjusting means is provided for obtaining the temperature T3. Based on the thermography image, the inspection unit 50 operates the temperature adjusting means so that the temperature of the conveying surface of the conveying belt 21B reaches the third temperature T3.

In the example of FIG. 3, the temperature control means arranged on the belt conveyor 20A is constituted by the blower 60, and the temperature control means arranged on the belt conveyor 20B is constituted by the temperature control device . The temperature control device 70 may be provided with heat applying means for applying heat by contacting the conveyor belt 21B, or may be provided with heat applying means for applying heat in a non-contact manner. As for the form of the heat imparting means, if it is a contact type, it is roller-shaped or plate-shaped. can. Further, the temperature control device 70 may be divided into several areas whose temperature can be set individually, so that temperature unevenness that may occur in the conveying belt 21B can be dealt with more finely. In any case, since the conveying belt 21B is insulated from the heat application device 30, the temperature control device 70 can be small and does not need to have high performance.

Such a configuration has the following advantages. That is, in the process of being conveyed by the belt conveyor 20A, a temperature change occurs in the part on the bottom side of the package 1 that is in contact with the conveyor belt 21A, and after being transferred to the belt conveyor 20B, that part comes into contact with the conveyor belt 21B. As a result, an undesirable temperature change may occur in the conveyor belt 21B. However, according to the configuration of FIG. 3, such temperature changes can be suppressed more effectively than simply dividing the conveying means.

If a sufficient effect can be obtained from one of the blower 60 and the temperature control device 70, provision of the other temperature control means is unnecessary. However, if a temperature control device is provided for the conveying belt 20B on the downstream side, the temperature of the conveying belt 21B can be finely and flexibly controlled, thereby making it possible to detect sealing defects with higher accuracy. In addition, in order to eliminate the influence (thermal expansion or contraction, deterioration due to excessively high or low temperature, etc.) of the conveying belt 21A due to the heat continuously applied by the heat applying device 30, the conveying belt 21A in this embodiment It is preferable to dispose the blower 60 with respect to. Furthermore, the blower 60 and the temperature control device 70 may be controlled simultaneously by the inspection unit 50, or may be controlled individually based on predetermined temperature conditions.

A temperature control device similar to that provided for the belt conveyor 20B can also be provided for the belt conveyor 20 of the first embodiment described above. However, the conveying belt 21 of the first embodiment is longer than the conveying belt 21B, and requires a large-sized, high-performance temperature control device. Advantageous.

(Third Embodiment)
FIG. 4 is a schematic diagram showing a package product inspection apparatus according to a third embodiment of the present invention. This embodiment employs the same conveying system as in the second embodiment, but instead of the temperature control device 70, a background light source unit 80 for irradiating the conveying surface of the conveying belt 21B with infrared rays is provided. A conveying belt 21B is used in which a material (for example, metal) that reflects the light appears on the conveying surface. In this embodiment, the temperature is not adjusted based on the condition of the background temperature (or the temperature difference between the background temperature and the seal portion 5), but the infrared camera 40 captures the infrared rays reflected by the conveying belt 21B. creating a background temperature T3. However, it goes without saying that the wavelength of the infrared rays corresponds to the temperature at which the outline of the lid 3 can be clearly recognized.

In this embodiment, reflection is used to create the apparent background temperature T3, but transmission may be used. In this case, the conveying belt 21B may be configured to transmit infrared rays (for example, a mesh belt), and the background light source section 80 may be arranged on the back side of the conveying surface of the conveying belt 21B.

(Fourth embodiment)
The inventors further found that when the first temperature T1<the second temperature T2 is set and the package 1 is transported at high speed, the temperature of some regions of the lid 3 becomes lower than the other regions. I found that the part appeared.
This will be explained using FIG. The figure shows the flow of air relative to the package 1 when it is conveyed in the F direction. When the package 1 has a columnar shape (the lid 3 is circular), the density of streamlines, ie, the flow velocity, is high at the sides of the package 1 or the lid 3 . Then, the portion 9 of the package 1 or the side portion of the lid 3 (the portion surrounded by the outer circumference and the two-dot chain line) that is in contact with the portion where the flow velocity is high is deprived of heat, and the first temperature T1 and the The second temperature T2 having a preferable temperature difference between the two cannot be maintained, and the outline of the lid 3 or the identification of the seal portion 5 cannot be accurately performed.

Therefore, the fourth embodiment of the present invention provides a configuration that more clearly captures the outline of the lid 3 and further improves the detection accuracy of the foreign matter 7 or seal failure.

FIG. 6 is a schematic diagram showing a package product inspection apparatus according to the fourth embodiment, which basically has the same configuration as that of the first embodiment. This embodiment differs from the first embodiment in that an air blower 90 is arranged to blow air from upstream in the conveying direction to the packages 1 being conveyed. The air blower 90 blows air from the rear of the package 1 at a wind speed corresponding to the transport speed, thereby apparently reducing the relative air flow accompanying the transport. Since the air from the blower 90 reaches the second temperature T2 by passing through the area of the heat applying device 30, it is possible to suppress an undesirable temperature drop in the side portions of the lid 3. FIG.

It goes without saying that the blower 90 should be arranged at a position that does not interfere with the transportation of the package 1 . Also, if there is a concern that air blowing to the preceding package may be blocked by the following package, the position of the air blower 90 and the air blowing direction may be appropriately adjusted. Further, the conveying path may be bent as appropriate so that appropriate air is blown sequentially to each of the plurality of packages being conveyed. In addition, this embodiment can be combined not only with the first embodiment, but also with the second or third embodiment.

(others)
The invention is not limited to the several embodiments described above and the variants mentioned throughout. For example, in each of the above-described embodiments, the lid 3 made of an aluminum laminate film and the contents to be inspected were cup noodles. Since it can be effectively applied to a non-permeable lid, it may be made of, for example, a colored plastic material.

Another example of the packaged product 1 to which the present invention can be preferably applied is a cup product containing tofu, pudding, jelly, or the like. This is because the liquid, which is part of the contents, adheres to the sealing portion 5 during the filling process, which may cause a sealing failure.

Furthermore, in the above embodiment, it is assumed that the package 1 to be inspected is initially at the ambient temperature. However, the first temperature T1 does not have to be the environmental temperature. Moreover, if at least the lid 3 exhibits the first temperature T1, the entire package 1 need not be at the first temperature T1.

In addition, in the above-described first and second embodiments, the blower 60 or the temperature control device 70 detects the background temperature (or the temperature difference between the background temperature and the seal portion 5) detected by the inspection unit 50. It may be on/off controlled, or controlled so that the wind speed, air volume, or air temperature of the blower 60 or the amount of heat given by the temperature control device 70 is changed.

REFERENCE SIGNS LIST 1 Package 3 Lid 5 Sealing Part 7 Foreign Matter 9 Side Part of Lid 21 Conveyor Belt 30 Heating Device 40 Infrared Camera 50 Inspection Unit 60, 90 Air Blower 70 Temperature Control Device 80 Background Light Source Part

Claims (10)

An inspection apparatus for packaged goods, comprising: a container body having an opening for storing contents and exposing the contents; and a lid sealed to the container body so as to close the opening. There is
a conveying means for conveying the package at a first temperature;
heat applying means for changing the lid to a second temperature different from the first temperature in the course of the transportation;
detection means for capturing a thermographic image representing the distribution of the surface temperature of the lid using an infrared camera and detecting a defect in the sealing portion between the container body and the lid based on the thermographic image;
with
An inspection apparatus for packages, wherein the conveying surface exhibits a third temperature at which a boundary between the outline of the lid and the conveying surface of the conveying means appears clearly in the thermographic image. 2. The package inspection apparatus according to claim 1, further comprising a temperature adjusting means for adjusting the temperature of said conveying means so that said conveying surface exhibits said third temperature. The conveying means is divided into an upstream conveying means for conveying the packaged product to the heat applying means and a downstream conveying means for conveying the packaged product to the infrared camera. 2. The method of claim 1, wherein the downstream transport means is insulated from the downstream transport means so that the transport surface of the downstream transport means exhibits the third temperature. Inspection equipment for package products. At least one of the upstream conveying means and the downstream conveying means is provided with a temperature adjusting means for adjusting the temperature so that the conveying surface of the downstream conveying means exhibits the third temperature. 4. The package product inspection device according to claim 3, characterized by: The downstream conveying means is configured to reflect or transmit infrared rays, and includes a light source section that irradiates the downstream conveying means with infrared rays corresponding to the third temperature, and the detecting means includes the thermography. 4. The package inspection apparatus according to claim 3, wherein the light source unit irradiates the infrared rays based on an image. 6. The package inspection according to any one of claims 1 to 5, further comprising an air blower that blows air at a speed corresponding to the transport speed of the package from upstream in the transport direction of the transport means. Device. 7. A packaged goods inspection apparatus according to claim 1, wherein said heat application means applies heat to said packaged goods by radiant heat transfer or convection heat transfer. 8. A packaged goods inspection apparatus according to claim 1, wherein said detection means uses an infrared camera having sensitivity to far infrared rays. When the content or a part thereof is caught in the sealed portion, the detection means detects a portion of the sealed portion where the caught content and a portion of the sealed portion where the content is not caught. 9. The package inspection apparatus according to any one of claims 1 to 8, wherein sealing defects are detected based on the temperature distribution of the seal portion appearing in the thermography image due to the difference in heat capacity between the seal portions. A package at a first temperature, comprising: a container body having an opening for containing contents and exposing the contents; and a lid sealed to the container body so as to close the opening. An inspection method for inspecting a product while it is being transported by a transport means,
a heat applying step of changing the lid to a second temperature different from the first temperature using heat applying means;
an adjusting step of adjusting the conveying surface of the conveying means to exhibit a third temperature;
a detection step of capturing a thermographic image representing the distribution of the surface temperature of the lid using an infrared camera, and detecting a defect in a sealing portion where the container body and the lid are bonded based on the thermographic image;
and wherein the third temperature adjusted in the adjusting step is a temperature at which a boundary between the outline of the lid and the conveying surface appears clearly in the thermographic image. Inspection methods.

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