Systems and methods for detecting container breakage

Abstract

A leak detection system for detecting breaches in sealed food containers is disclosed. The leak detection system includes a first optical sensor configured to transmit an optical signal through a first inspection path, the first optical sensor being capable of detecting variations in gas composition. A permeable press member is configured to apply pressure to the sealed food container during use. The first optical sensor is positioned such that at least a portion of the first inspection path through which the optical signal is transmitted is located behind or within the permeable press member.

Description

[Technical Field]

[0001] The present invention relates to a system and method for detecting breaches in sealed containers, particularly sealed atmosphere-modified food containers such as trays and packets. [Background technology]

[0002] Modified atmosphere packaging (MAP) is widely used in the food packaging industry as a way to reduce product spoilage and extend shelf life. MAP typically involves changing the composition of the gases present with the food in the food container so that it differs from the standard atmospheric composition in a way that maximizes the life of the food. This usually involves increasing or decreasing the percentage of oxygen, nitrogen, and / or carbon dioxide in the air within the food package.

[0003] When foods are packaged using modified atmosphere packaging, imperfect sealing of the package allows the atmosphere within the package to revert to standard atmospheric composition, thereby reducing or completely negating the shelf life extension provided by the MAP process.

[0004] To identify damaged containers, i.e., containers with openings and incomplete sealing, packages are mechanically inspected. Mechanical inspection typically involves mechanically compressing the container, increasing pressure within the sealed package, and determining the expected response of the package as it resists the mechanical compression. These methods of mechanically testing packages are typically very slow, which can limit maximum production speeds or require many separate lanes to accommodate faster packaging systems. Additionally, mechanical systems are typically limited in the size of leaks they can detect, often failing to detect breaks smaller than 1.0 mm.

[0005] Recently, laser technology has been developed that can accurately and precisely determine carbon dioxide content and other species. This laser technology is based on a principle called tunable diode laser absorption spectroscopy (TDLAS), which uses a tunable diode laser and laser absorption spectroscopy to measure the concentration of species in a gas mixture. Compared to other measurement techniques, such as paramagnetic detectors (PMDs) and chemiluminescence (CEM), TDLAS offers multi-element detection capabilities, high accuracy with a wide dynamic range, low maintenance requirements, and a long life cycle. Using a laser as a spectroscopic light source enables high-resolution spectroscopy (HRS) using quantum cascade lasers (QCLs), which provide access to the important mid-infrared (MIR) region of the electromagnetic spectrum. An example of a QCL system can be found in WO 2003 / 087787.

[0006] This type of technology has been incorporated into in-line systems for detecting breakage in food containers, as detailed in WO 2019 / 076838. Here, a laser beam is positioned to extend directly above the food container and detects gas released when adjacent rollers or other devices compress the container. This has been found to provide reasonably reliable leak detection. While the sensitivity of optical technology is currently sufficient to detect breakages smaller than 1.0 mm, this implementation has been found to underutilize this high sensitivity. Therefore, it would be desirable to provide improved and integrated techniques for this relatively new leak detection technology to further increase its reliability and efficiency. Summary of the Invention [Problem to be solved by the invention]

[0007] According to a first aspect of the present invention, there is provided a leak detection system for detecting breaches in sealed food containers, the leak detection system comprising: a first optical sensor configured to transmit an optical signal through a first test path and capable of detecting variations in gas composition (i.e., gas impinging on the optical signal transmitted along the test path); and a transmissive press member configured to apply pressure to the sealed food container in use, the first optical sensor being positioned such that at least a portion of the first test path along which the optical signal is transmitted is located behind or within the transmissive press member.

[0008] In this system, a permeable press member is provided, which is configured to apply pressure to a sealed food container, for example, using the press surface of the press member. Such a permeable press member allows gas to pass through the press surface of the press member. This ensures that, for example, gas released from the container when pressure is applied passes through the press surface of the press member and reaches the interior or rear of the press member. Furthermore, the first optical sensor is positioned so that at least a portion of the first inspection path is located behind or inside the permeable press member. For example, the inspection path can be located behind the press surface of the press member, i.e., on the side of the press surface that contacts the sealed food, with the container in contact with the outer surface of the press member, or it can be located within the permeable press member. Thus, gas passing through the press member impinges on light passing along the inspection path, changing the optical properties of the transmitted light as described above.

[0009] The system includes an inspection path that can be positioned closer to the contact point between the press member and the sealed food container. In known systems, when pressure is applied to the sealed food container, it can bulge or inflate on both sides of the contact point. This is particularly problematic when the sealed food container is a food bag. Because of this effect, known systems must provide sufficient clearance between the beam path and the sealed food container to prevent the container itself from impinging on the inspection path and blocking the transmitted light. In fact, the inventors discovered that in known systems in which detection is performed at the leading or trailing edge of the roller, the optical sensor is laterally offset from the press position, resulting in a significant decrease in sensitivity. In the present system, the press member itself prevents the container from blocking the inspection path and the inspection path is located behind or inside the press member, allowing the sensor to be positioned as close as possible to the contact point with the container. Locating the inspection path closer to the contact point with the sealed food container improves the sensitivity and reliability of the leak detection process.

[0010] As described above, the first optical sensor can detect variations in gas composition. For example, the optical sensor may be able to detect variations in the percentage of carbon dioxide or nitrogen in the air impinging on the inspection path. Thus, if a breach exists in the atmosphere-changed packaging, the press member may cause gas to be expelled from the container, which may result in a sudden increase or decrease in the percentage of one or more gases near the inspection path. The optical sensor can then detect such changes in gas composition, from which a breach in the sealed food container can be inferred.

[0011] The first optical sensor can transmit light along a substantially one-dimensional inspection path, such as a laser beam path, but if a larger inspection area is required, the path can extend to two dimensions, such as a line-focused laser illuminating a plane. However, to ensure that it is possible to reliably determine which containers are damaged, the inspection path preferably does not exceed the length of the containers being tested. For this reason, a laser beam may be preferred to provide greater accuracy.

[0012] Preferably, the system further includes a conveyor for transporting the sealed food containers through the leak detection system. For example, the conveyor may transport the sealed food containers on a conveyor belt and past a press member, wherein at least a portion of a pressure surface of the press member may be disposed between the inspection path and the conveyor.

[0013] The press member may be advantageously configured to apply pressure to the sealed food containers while they are moving through the leak detection system, for example, while being moved by the aforementioned conveyor. This eliminates the need to stop the sealed food containers for the inspection process, thereby increasing the throughput of the system. Examples of suitable press members are provided below, but generally, the press member requires a movable or rotatable pressure surface that contacts the sealed food containers as they move through the system.

[0014] In a preferred embodiment, the permeable press member is positioned opposite the conveyor such that the sealed food containers can pass between the permeable press member and the conveyor, i.e., the conveyor moves the sealed food containers through the system, carrying them into a gap between the permeable press member and the conveyor, increasing the pressure within the sealed food containers as they pass through the gap.

[0015] Preferably, the system further includes a control unit connected to the first optical sensor, the control unit receiving a signal from the first optical sensor and determining the presence of a breach in the sealed food container based on the signal from the first optical sensor. For example, the control unit may determine that the sealed food container has a breach when one or more threshold values ​​for one or more gases sensed by the optical sensor are exceeded. Alternatively, the determination may be based on a rate of change of the gas composition.

[0016] In some embodiments, the control unit is configured to receive information regarding the position of the sealed food container relative to the first optical sensor, and the control unit is configured to determine the location of a break in the sealed food container based on the signal of the first optical sensor and the information regarding the position of the sealed food container. The information regarding the location of the sealed food container can be obtained from an optical gate configured to detect the leading and trailing edges of the container as it passes under the press member and the optical sensor. In other examples, weight sensors, cameras, or the like can be used to determine the location of the container within the system or upstream of the system. The controller can also be connected to a conveyor, and the speed of the conveyor can be used to track the location of the container as it moves through the system. Identifying the location of the break can help identify faults in upstream sealing machines. For example, if breaks are regularly observed on the trailing edge of the container, this can be used to identify the cause of the sealing error, such as debris on the corresponding end of the sealing tool.

[0017] In many embodiments, the control unit is configured to determine the magnitude (i.e., size) of the break based on the signal of the first optical sensor. For example, the optical sensor signal can detect a peak in the change in gas composition or a rate of change in the gas composition, and one or both of these can be used to infer the size of the break in the container. This can be adjusted by using sample containers with various break sizes to determine typical gas composition fluctuation profiles for various break sizes. The controller can determine whether the container is "good" or "bad" based on the determined size of the break. For example, in a sealed food container, very small tears may be within the acceptable range. Nevertheless, being able to detect and monitor the occurrence of small breaks can still be valuable for identifying problems with the sealing machine.

[0018] In a particularly preferred embodiment, the permeable press member comprises a first permeable conveyor belt, which can be positioned above and opposite a conveyor such that the sealed food containers pass between the two conveyors to increase pressure. Advantageously, the permeable conveyor belt facilitates the provision of an inspection path within the press member, i.e., the inspection path can extend within the conveyor belt, for example, between both sides of the conveyor belt.

[0019] Preferably, the first permeable conveyor belt includes a series of openings therethrough to allow gas to permeate therethrough. For example, the conveyor belt may have a series of holes or slots therethrough to allow gas to pass through and impinge on the inspection path.

[0020] The first permeable conveyor belt may also include an array of protruding elements that contact the sealed food container and separate the main body of the conveyor belt, i.e., the majority of the belt, from the surface of the sealed food container. The array of protruding elements reduces the contact area between the pressing element and the container, preventing the pressing element from inadvertently sealing the container. Suitable protruding elements include bumps or elongated ridges.

[0021] In particularly preferred embodiments, the first optical sensor is positioned such that at least a portion of its inspection path is located within the first transparent conveyor belt and extends through the width of the conveyor belt, i.e., perpendicular to its conveying direction. This typically provides a convenient location for the physical elements of the first optical sensor, i.e., a lateral opening in the wrapped conveyor belt, allowing the inspection path to extend to all or most of the possible contact locations.

[0022] In some embodiments, a first permeable conveyor belt is preferred, but in other embodiments, the permeable press member may include, for example, a permeable roller.

[0023] In embodiments where a conveyor is provided for transporting sealed containers to and / or from the permeable press member, the conveyor preferably includes a permeable conveyor, and the first or second optical sensor capable of detecting gas composition fluctuations transmits a second optical signal through a second inspection path, the optical sensor being positioned such that at least a portion of the second inspection path through which the second optical signal is transmitted is located behind or within the permeable conveyor. Essentially, in these embodiments, the lower conveyor on which the containers are placed during transport also functions as a press member for extracting gas samples through breakage of the containers. This is particularly preferred when the sealed food containers are configured to be sandwiched between the conveyor and the permeable press member, i.e., when the sealed containers pass through the gap formed between the two.

[0024] The permeable conveyor preferably comprises a second permeable conveyor belt, which may have all of the features described above with respect to the first permeable conveyor belt, i.e., the openings, protruding elements, and inspection path arrangement. For example, the optical sensor may also be positioned such that at least a portion of the second inspection path is located within the second conveyor belt and extends across the width of the conveyor belt.

[0025] As mentioned above, the second inspection path can be formed by the same optical sensor that provides the inspection path within the transparent press member. This can be achieved, for example, by a mirror arrangement that directs light downward within the second conveyor belt, providing a single optical path along both sides of the container, with the received optical signal received by a single optical detector. Alternatively, the second inspection path can be provided by a second optical sensor distinct from the first optical sensor. This can be useful for identifying which side of the container is damaged and for diagnosing seal or other manufacturing defects. Two light sources can be provided, transmitting light along two paths, or a single light source can be provided where the light is split into two paths and received by respective optical detectors.

[0026] In embodiments in which a second optical sensor is used, the first optical sensor is preferably capable of detecting variations in gas composition along the first inspection path, and the second optical sensor is preferably capable of detecting variations in gas composition along the second inspection path. For example, the optical signal along the first inspection path may be separated from the optical signal along the second inspection path, and these optical signals may be received by respective optical detectors capable of detecting optical signals transmitted by the light source. Preferably, a control unit is connected to the second optical sensor and configured to receive signals from the second optical sensor, and the control unit is configured to determine the location of the break based on the signals from the first optical sensor and the second optical sensor. As described above, this may allow, for example, breakage in the top and bottom of a sealed food container to be distinguished. The control unit may be configured to determine the location of the break by comparing the signals from the first optical sensor and the second optical sensor. For example, if one sensor experiences a larger variation in gas composition than the other, or if one sensor detects a break but not the other, this can be used to infer that the break is located on or towards the side of the vessel near that sensor.

[0027] In a particularly preferred embodiment, the permeable press member is adjustably mounted on the conveyor so that the distance between the press member and the conveyor can be varied to accommodate different sizes of sealed food containers. Although preferred, the two can alternatively be fixed relative to one another.

[0028] In many embodiments, an optical sensor is attached to the transmissive press member. For example, an optical sensor may be attached within the transmissive conveyor belt. This is particularly useful for adjusting the positioning of the press member. If a second optical sensor is provided in the transmissive conveyor, it may likewise be attached to the conveyor, for example within the second conveyor belt.

[0029] Preferably, the optical sensors include one or more light sources, preferably lasers, configured to transmit optical signals, and each optical sensor includes a detector capable of detecting the optical signals transmitted by said light sources. As mentioned above, the two optical sensors are characterized by respective detectors for receiving light after passing through respective inspection paths and detecting variations in gas composition. However, the light may be transmitted by one and the same light source, for example using a splitter, or by respective light sources.

[0030] According to a second aspect of the present invention, there is provided a method of detecting failure of a sealed food container, comprising applying pressure to the sealed food container using a transmissive press member and detecting variations in gas composition behind or within the transmissive press member using an optical sensor configured to transmit an optical signal through an inspection path, the optical sensor being positioned such that at least a portion of the inspection path through which the optical signal is transmitted is located behind or within the transmissive press member.

[0031] This corresponds to a method of using the system according to the first aspect, and therefore all preferred features of that system apply equally to the method according to the second aspect.

[0032] As explained above, one advantage of the present invention is that it allows for a more accurate determination of the size and / or location of a breach in a container, and therefore preferably the method includes making a determination regarding the size and / or location of the breach. For example, the method may include determining a magnitude of breach of the sealed food container based on a variation in gas composition detected using the first optical sensor, which may be based on the magnitude of the detected variation or the rate of variation in the gas composition, as described above.

[0033] Preferably, pressure is applied to the sealed food container using a transparent press member while the sealed food container is moving relative to the first optical sensor, and the method further includes determining a location of a breach in the sealed food container based on the detected variation in gas composition and the position of the sealed food container relative to the first optical sensor.

[0034] Preferably, the method further includes detecting variations in gas composition using a second optical sensor configured to transmit an optical signal through a second inspection path, the sealed food container being positioned or passed between the first and second inspection paths, and determining a location of damage to the sealed food container based on the variations in gas composition detected by the first optical sensor and the variations in gas composition detected by the second optical sensor, i.e., the two sensors can determine whether the damage is closer to the first or second optical sensor, indicating whether the damage is at the top or bottom of the container, for example. [Brief explanation of the drawings]

[0035] [Figure 1] FIG. 1 is a side view of a leak detection system according to one embodiment. [Figure 2] FIG. 2 is a plan view of the leak detection system shown in FIG. 1. [Figure 3] FIG. 3 is an end view of the leak detection system shown in FIGS. 1 and 2. [Figure 4] FIG. 4 is an end view of the leak detection system shown in FIGS. 1 to 3 with the conveyor belt omitted to reveal the placement of the optical sensors. [Figure 5] FIG. 10 is an end view of the second leak detection with the conveyor belt omitted to reveal the location of the optical sensor. DETAILED DESCRIPTION OF THE INVENTION

[0036] A first embodiment of the leak detection system will be described with reference to FIGS.

[0037] The leak detection system 1 includes first and second opposing conveyor systems 100, 200. The upper conveyor 100 includes a conveyor belt 101 wound around a series of rollers 102a, 102b, 102c, and 102d. Drive rollers 102a and 102b are located at the upstream and downstream ends of the conveyor 100 and determine the length of the conveyor. Auxiliary rollers 102c and 102d are provided to adjust the shape of the wound conveyor belt 101. In particular, the conveyor belt 101 is wound around the rollers 102a, 102b, 102c, and 102d so that the bottom surface of the conveyor belt is substantially flat. That is, the drive rollers 102a and 102b are located at the same height, and the bottom surface extends between the drive rollers 102a and 102b without changing direction. Meanwhile, the top surface of the conveyor belt passes around auxiliary rollers 102c, 102d, located toward the center of the conveyor, to separate the top surface of the conveyor from the flat underside. This increases the clearance between the top and bottom surfaces of the conveyor belt 101, providing space for internal components, discussed further below. While only these rollers are shown in this embodiment, it should be understood that additional retraction rollers can be provided as needed to support and maintain the shape of the conveyor belt.

[0038] The second conveyor 200 similarly comprises a conveyor belt 201 entrained around rollers 202a, 202b, 202c, and 202d. First and second drive rollers 202a and 202b are located at the upstream and downstream ends of the conveyor 200 and define the length of the conveyor. Rollers 202a and 202b provide a substantially flat upper surface for the second conveyor 200, while auxiliary rollers 202c and 202d separate the lower surface of the belt from the upper surface to provide space for internal components within the conveyor. Again, additional rollers can be provided as needed. In particular, because this conveyor 200 can support items being transported through the system, additional rollers along the length of the conveyor may be required to support the upper surface of the conveyor belt 201.

[0039] As described above, the conveyors 100 and 200 oppose one another. The flat lower surface of the upper conveyor 100 and the flat upper surface of the lower conveyor 200 define a gap of substantially constant height between the two opposing conveyor systems 100, 200. During use, a container 10 is carried toward the leak detection system 1 by an upstream conveyor (not shown) so that the container enters between the opposing conveyors 100, 200 at the upstream end of the system 1. The two conveyors 100, 200 are driven by respective sets of drive rollers 102a, 102b, 202a, 202b such that the belts 101, 102 transport the container 10 through the system. This movement of the two conveyor belts 101, 201 draws the container 10 into the gap between the two conveyors 100, 200, where the container 10 is compressed by the opposing conveyor belt surfaces.

[0040] As shown in Figure 2, a first conveyor belt 101 includes a series of openings extending therethrough in the form of an array of slots 103. These slots 103 allow gas to pass through the conveyor belt surface 101. In particular, when the container 10 is compressed, modified atmosphere within the container can escape through crevices in the container and pass through one of the slots 103. Although not shown, a second conveyor system 200 similarly includes a conveyor belt 201 with a similar array of openings that allow gas to pass through.

[0041] As shown in Figure 3, each conveyor belt 101, 201 also includes a series of protruding ridges 104, 204 extending along the conveying direction of the conveyor belt. As can be seen in Figure 3, these protruding ridges 104, 204 minimize the contact area between the conveyor belts 101 and 201 and the containers 10. This minimization of the contact area ensures that the surfaces of the conveyor belts 101, 102 do not inadvertently block the breakage of the sealed food containers 10.

[0042] As shown in FIGS. 1 and 4, the first and second conveyor systems 100 and 200 include respective optical sensors 110 and 210 positioned between the upper and lower surfaces of the respective conveyor belts 101 and 201. Both optical sensors 110 and 120 are positioned near the upstream ends of the conveyors. This ensures that when a container 10 enters the conveyors and pressure is applied, the optical sensors are properly positioned to detect the discharged gas before a significant amount of gas escapes. This improves the sensitivity of the system. The first optical sensor 110, located on the first conveyor 100, includes a light source 111 and a detector 112. The light source 111 may be a laser, such as a diode laser or semiconductor laser. The wavelength or wavelength range selected for the light source must match the absorption spectrum of at least one gas present in the gas exchange vessel 10. Preferably, the wavelength should be selected to match the absorption spectrum of the gas present in the vessel, with the absorption ratio maximally different from that of the ambient air. Detector 112 may be any photodetector capable of detecting the wavelength or range of wavelengths selected for light source 111, for example, a photodiode, a photomultiplier tube, a CCD detector, a CMOS detector, or an InGaAs detector.

[0043] The light source 111 is positioned on one side edge of the conveyor and is configured to transmit an optical signal 113 across the width of the conveyor 100 to a detector 112 located on the opposite side edge of the conveyor. The light source 111 and detector 112 are positioned proximate to the underside of the conveyor belt 101 so that the transmitted light 113 passes as close as possible to the containers 10 as it passes between the conveyors 100, 200. In this embodiment, the light source 111 is positioned on one side of the conveyor 100 and the detector 112 is positioned on the opposite side of the conveyor 100 so that the optical signal 113 extends across substantially the entire width of the conveyor 100 to provide maximum coverage and accommodate containers entering at various lateral positions.

[0044] As described above, the second conveyor 200, like the first optical sensor 110, also includes an optical sensor 210 that includes a light source 211 on one lateral side of the conveyor and a detector 212 on the opposite side of the conveyor. The light source 211 transmits an optical signal 213 across substantially the entire width of the conveyor 200. In this embodiment, the second light source 211 and second detector 212 are positioned such that the optical signal 213 extends along a path that is proximate to the top surface of the lower conveyor belt 200. Again, positioning the optical sensor 210 in this manner ensures that the optical signal is as close as possible to the containers 10 as it passes between the conveyors 100, 200.

[0045] During use, as a container 10 is conveyed through the leak detection system 1 between opposing conveyors 100, 200, the container 10 is subjected to applied pressure from being squeezed between the two conveyors. This applied pressure can cause gas to leak through a breach in the sealed container. As the container 10 passes between the optical sensors 110, 210, gas escaping from the breached container can penetrate through an opening through the conveyor belt 101 or 102 and impinge on the optical signal 113 or 213 of the respective optical sensor 110, 210. This gas impingement from inside the sealed container can thereby cause a variation in the composition of the gas through which the corresponding optical signal passes. This variation in gas composition can then be detected by the detector 112 or 212 as an increase or decrease in the intensity of the optical signal detected at a wavelength corresponding to the absorption spectrum of the gas. This change in intensity detected by the detector can be used to infer a breach in the container located between the optical sensors.

[0046] Both the first and second optical sensors 110, 210 are connected to the control unit 20 by respective wires 21, 22. In this embodiment, the control unit 20 is located within the upper conveyor, and the wire connecting to the second optical sensor 120 extends from the side of the upper conveyor 100 before being routed downward and into the side of the second conveyor 200 to connect to the second optical sensor 210. In other embodiments, the control unit can be located outside both conveyors. The control unit is connected to the detectors 112, 212 of the optical sensors 110, 210 and receives signals indicative of the gas composition of the gas impinging on the respective optical signals. In this manner, the control unit can process the gas composition data and determine the presence of a breach. For example, the control unit 20 can determine that a sealed food container 10 is breached if the container is filled with a displacement gas such as CO2, and a threshold CO2 concentration is exceeded or a specific rate of change in CO2 is detected.

[0047] This embodiment not only enables breakage detection, but can also be used to infer the type of upstream fault. In particular, the system can distinguish between breakages in the top or bottom of a container. For example, if only the first optical sensor 110 detects a fluctuation in gas composition, it can be inferred that the break is in the top of the container. Alternatively, the control unit 20 can compare signals between the two optical sensors 110, 210 to determine which sensor detected the greatest increase or decrease in concentration, with larger fluctuations indicating that the break is closer to that sensor. For example, if an abnormally high percentage of breakages are detected in the top or bottom of a container, this can be used to infer that there is a specific type of upstream problem. For example, regular breakages in the bottom of a container could indicate a problem with the bottom container sealing device or the container former. Alternatively, a high percentage of breakages in the top of a container can be used to infer a problem with the top container sealing device or the film itself.

[0048] Additionally, in combination with information regarding the container's position, this embodiment can be used to determine the location of a break along the container's conveying direction. For example, a light gate (not shown) can be positioned to detect a container passing between the first and second optical sensors 110, 210. The light gate signal is received and compared by the control unit 20 with the signals from the optical sensors 110, 210 to determine the location of the break along the conveying direction. For example, if a container triggers the light gate and an increase in CO2 is detected by the first optical sensor but not the second optical sensor, it may be inferred that there is a break along the top leading edge of the container. If breaks are detected regularly in a particular location, this can be used to diagnose faults in the upstream sealing system.

[0049] Another optical sensor arrangement is shown in Figure 5. In this embodiment, only one optical sensor 110 is provided. In this embodiment, the optical sensor comprises a light source 111 located within the upper conveyor 100 and a detector 112 located within the lower conveyor 200. The light source 111 is located at one side edge of the conveyor and transmits an optical signal 113 that travels along the width of the upper conveyor 100 and exits the opposite side of the conveyor 100. First and second mirrors 114a, 114b are provided to deflect the optical signal downwards onto the second conveyor 200, i.e., between the upper and lower surfaces of the belt 201. The optical signal travels across substantially the entire width of the second conveyor 200 and is received by the detector 112. The light source 111 is provided near the underside of the upper conveyor belt 101, and the detector is positioned near the upper surface of the lower conveyor belt 201 so that the optical signal 113 passes near both the top and bottom surfaces of the containers 10 passing between the conveyors 100, 200. This configuration therefore provides a single optical signal that passes along a path that extends through both conveyors 100, 200. This embodiment reduces the number of optical sensor components required to achieve sensitivity to variations in gas composition near both the top and bottom surfaces of the containers 10.

[0050] In FIG. 5, the control unit is not shown so that the arrangement of the optical signals can be seen more clearly, but the control unit may be located, for example, inside the lower conveyor 200 and connected to the detector 112. [Prior art documents] [Patent documents]

[0051] [Patent Document 1] International Publication No. 2003 / 087787 [Patent Document 2] International Publication No. 2019 / 076838

Claims

1. 1. A leak detection system for detecting breaches in sealed food containers, comprising: a first optical sensor configured to transmit an optical signal through a first inspection path and capable of detecting variations in gas composition; a permeable press member configured to apply pressure to the sealed food container in use; Equipped with the first optical sensor is positioned such that at least a portion of the first inspection path along which the optical signal is transmitted is located behind or within the transmissive press member; Leak detection system.

2. 10. The leak detection system of claim 1, further comprising a conveyor for transporting sealed food containers through the leak detection system.

3. 10. The leak detection system of claim 1, wherein the permeable press member is configured to apply pressure to the sealed food container while the sealed food container moves through the leak detection system.

4. 4. The leak detection system of claim 2 or claim 3 dependent on claim 2, wherein the permeable press member is positioned opposite the conveyor so that sealed food containers can pass between the permeable press member and the conveyor.

5. The leak detection system of any one of the preceding claims, further comprising a control unit connected to the first optical sensor, the control unit receiving a signal from the first optical sensor and determining the presence of damage in the sealed food container based on the signal from the first optical sensor.

6. 6. The leak detection system of claim 5, dependent on claim 3 or claim 4, wherein the control unit is configured to receive information regarding the position of the sealed food container relative to the first optical sensor, and the control unit determines the position of a break in the sealed food container based on the signal of the first optical sensor and the information regarding the position of the sealed food container.

7. 7. The leak detection system of claim 5 or claim 6, wherein the control unit is configured to determine the magnitude of the breach based on a signal from the first optical sensor.

8. 10. The leak detection system of claim 1, wherein the permeable press member comprises a first permeable conveyor belt.

9. 9. The leak detection system of claim 8, wherein the first permeable conveyor belt comprises a series of openings therethrough that allow gas to permeate through the first permeable conveyor belt.

10. 10. The leak detection system of claim 8 or claim 9, wherein the first permeable conveyor belt comprises an array of elements protruding from a surface of the first permeable conveyor belt for contacting the sealed food container and separating a body of the first permeable conveyor belt from the surface.

11. 11. The leak detection system of claim 8, wherein the first optical sensor is positioned such that at least a portion of the first inspection path is located within the first permeable conveyor belt and extends through a width of the first permeable conveyor belt.

12. 3. The leak detection system of claim 2, wherein the conveyor is a transmissive conveyor, the first optical sensor or the second optical sensor capable of detecting variations in gas composition is configured to transmit a second optical signal through a second inspection path, and the first optical sensor or the second optical sensor is positioned such that at least a portion of the second inspection path along which the second optical signal is transmitted is located behind or within the transmissive conveyor.

13. The leak detection system of claim 12 , wherein the permeable conveyor comprises a permeable conveyor belt.

14. 14. The leak detection system of claim 13, wherein the first optical sensor or the second optical sensor is positioned such that at least a portion of the second inspection path is located within the permeable conveyor belt and extends through a width of the permeable conveyor belt.

15. 15. The leak detection system of claim 12, wherein a second optical sensor capable of detecting variations in gas composition is configured to transmit a second optical signal through a second inspection path, the first optical sensor capable of detecting variations in gas composition in the first inspection path, and the second optical sensor capable of detecting variations in gas composition in the second inspection path.

16. 16. The leak detection system of claim 15, when dependent on claim 5, wherein the control unit is connected to the second optical sensor and configured to receive a signal from the second optical sensor, and the control unit is configured to determine a location of a break based on the signal from the first optical sensor and the signal from the second optical sensor.

17. 17. The leak detection system of claim 16, wherein the control unit is configured to determine a location of a breach by comparing a signal from the first optical sensor with a signal from the second optical sensor.

18. 3. The leak detection system of claim 2, wherein the permeable press member is adjustably mounted on the conveyor such that the distance between the permeable press member and the conveyor can be changed to accommodate different sizes of sealed food containers.

19. 10. The leak detection system of claim 1, wherein the first optical sensor is attached to the transmissive press member.

20. 10. The leak detection system of claim 1, wherein the first optical sensor comprises one or more light sources configured to transmit the optical signal, and each optical sensor comprises a detector capable of detecting the optical signal transmitted by the light source.

21. 1. A method for detecting breakage of a sealed food container, comprising: applying pressure to the sealed food container using a permeable press member; detecting variations in gas composition behind or within the transmissive press member using a first optical sensor configured to transmit an optical signal through a first inspection path; the first optical sensor is positioned such that at least a portion of a first inspection path along which an optical signal is transmitted is located behind or within a transmissive press member; How to detect breakage in sealed food containers.

22. 22. The method of claim 21, comprising determining the extent of a breach in the sealed food container based on a variation in gas composition detected using the first optical sensor.

23. 23. The method of claim 21 or claim 22, comprising applying pressure to the sealed food container using a transparent press member while the sealed food container is moving relative to the first optical sensor, and further comprising determining a location of a breach in the sealed food container based on the detected variation in gas composition and the position of the sealed food container relative to the first optical sensor.

24. 24. The method of any one of claims 21 to 23, further comprising detecting variations in gas composition using a second optical sensor configured to transmit an optical signal through a second inspection path, the sealed food container being located or passing between the first inspection path and the second inspection path, and determining a location of a breach in the sealed food container based on the variations in gas composition detected by the first optical sensor and the variations in gas composition detected by the second optical sensor.

25. 25. A method according to any one of claims 21 to 24, carried out using a system according to any one of claims 1 to 20.

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